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Title: The Ocean World: - Being a Description of the Sea and its Living Inhabitants.
Author: Groom-Napier, Charles O., Figuier, Louis
Language: English
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THE OCEAN WORLD.

LONDON: PRINTED BY WILLIAM CLOWES AND SONS, STAMFORD STREET AND CHARING
CROSS.

[Illustration: Plate I.--The Argonaut sailing in the open sea.]



    THE

    OCEAN WORLD:

    BEING A DESCRIPTION OF

    THE SEA AND ITS LIVING INHABITANTS.

    BY
    LOUIS FIGUIER.

    THE CHAPTERS ON CONCHOLOGY REVISED AND ENLARGED
    BY CHARLES O. GROOM-NAPIER, F.G.S., &c.

    WITH 427 ILLUSTRATIONS.

    LONDON:
    CASSELL, PETTER, AND GALPIN;
    AND 596, BROADWAY, NEW YORK.



PREFACE.


"Our Planet is surrounded by two great oceans," says Dr. Maury, the
eminent American _savant_: "the one visible, the other invisible; one is
under foot, the other over head. One entirely envelopes it, the other
covers about two-thirds of its surface." It is proposed in "THE OCEAN
WORLD" to give a brief record of the Natural History of one of those
great oceans and its living inhabitants, with as little of the
nomenclature of Science, and as few of the repulsive details of Anatomy,
as is consistent with clearness of expression; to describe the ocean in
its majestic calm and angry agitation; to delineate its inhabitants in
their many metamorphoses; the cunning with which they attack or evade
their enemies; their instructive industry; their quarrels, their
combats, and their loves.

The learned Schleiden eloquently paints the living wonders of the deep:
"If we dive into the liquid crystal of the Indian Ocean, the most
wondrous enchantments are opened to us, reminding us of the fairy tales
of childhood's dreams. The strangely-branching thickets bear living
flowers. Dense masses of _Meandrineas_ and _Astreas_ contrast with the
leafy, cup-shaped expansions of the _Explanarias_, and the
variously-branching _Madrepores_, now spread out like fingers, now
rising in trunk-like branches, and now displaying an elegant array of
interlacing tracery. The colouring surpasses everything; vivid greens
alternate with brown and yellow; rich tints, ranging from purple and
deepest blue to a pale reddish-brown. Brilliant rose, yellow, or
peach-coloured _Nullipores_ overgrow the decaying masses: they
themselves being interwoven with the pearl-coloured plates of the
_Retipores_, rivalling the most delicate ivory carvings. Close by wave
the yellow and lilac Sea-fans (_Gorgonia_), perforated like delicate
trellis-work. The bright sand of the bottom is covered with a thousand
strange forms of sea-urchins and star-fishes. The leaf-like _Flustræ_
and _Escharæ_ adhere like mosses and lichens to the branches of
coral--the yellow, green, and purple-striped limpets clinging to their
trunks. The sea-anemones expand their crowns of tentacula upon the
rugged rocks or on flat sands, looking like beds of variegated
ranunculuses, or sparkling like gigantic cactus blossoms, shining with
brightest colours.

"Around the branches of the coral shrubs play the humming-birds of the
ocean: little fishes sparkling with red or blue metallic glitter, or
gleaming in golden green or brightest silvery lustre; like spirits of
the deep, the delicate milk-white jelly-fishes float softly through the
charmed world. Here gleam the violet and gold-green Isabelle, and the
flaming yellow, black, and vermilion-striped Coquette, as they chase
their prey; there the band-fish shoots snake-like through the thicket,
resembling a silvery ribbon glittering with rose and azure hue. Then
come the fabulous cuttle-fishes, in all the diaphanous colours of the
rainbow, but with no definite outline.

"When day declines, with the shades of night this fantastic garden is
lighted up with renewed splendour. Millions of microscopic medusæ and
crustaceans, like so many glowing sparks, dance through the gloom. The
Sea-pen waves in a greenish phosphorescent light. Whatever is beautiful
or wondrous among _fishes_, _Echinoderms_, _jelly-fishes_ and _polypi_
and _molluscs_, is crowded into the warm and crystal waters of the
Tropical ocean."

It is stated on the Title-page that "THE OCEAN WORLD" is chiefly
translated from M. Louis Figuier's two most recent works. In justice to
that gentleman, we must explain this statement. The History of the Ocean
is to a large extent, but not wholly, compiled from "La Terre et les
Mers," one of the volumes of M. Figuier's "Tableau de la Nature;" but
the larger portion of the work is a free translation of that author's
latest work, "La Vie et les Moeurs des Animaux." Other chapters, such as
"Life in the Ocean," the chapter on Crustaceans, and some others, are
compiled from various sources; they will not be found in either of M.
Figuier's volumes; but in other respects his text has been pretty
closely followed.

       *       *       *       *       *

M. Figuier's plan is to begin the study of animals with the less perfect
beings occupying the lower rounds of the Zoological ladder, his reason
for doing so being an impression that the presence of the gradually
perfecting animal structure, from the simplest organisms up to the more
perfect forms, was specially calculated to attract the reader. "What can
be more curious or more interesting to the mind," he asks, "than to
examine the successive links in the uninterrupted chain of living beings
which commence with the Infusoria and terminate in Man?"

The work, he hopes, is not without the impress of a true character of
novelty and originality; at least he knows no work in which the strange
habits and special interests of the Zoophytes and Molluscs can be
studied, nor any work in which an attempt is made to represent them by
means of designs at once scientifically correct and attractive from the
picturesque character of the illustrations, most of which have been made
from specimens selected by Monsieur Ch. Bévalet from the various museums
in Paris.

One of those charming plain-speaking children we sometimes meet with
lately said to M. Figuier, "They tell me thou art a vulgariser of
Science. What is that?"

He took the child in his arms, and carried it to the window, where there
was a beautiful rose-tree in blossom, and invited it to pull a rose. The
child gathered the perfumed flower, not without pricking itself cruelly
with the spines; then, with its little hands still bleeding, it went to
distribute roses to others in the room.

"Thou art now a vulgariser," said he to the child; "for thou takest to
thyself the thorns, and givest the flowers to others!"

The parallel, although exaggerated, is not without its basis of truth,
and was probably suggested by the criticism some of his works have met
with; the critics forgetting apparently that these works are an attempt
to render scientific subjects popular, and attractive to the general
reader.

       *       *       *       *       *

In the present edition of "THE OCEAN WORLD" it is only necessary to add
to the above (dated January, 1868), that the work has been revised
throughout, and some not unimportant errors corrected. For several of
these I am indebted to Mr. C. O. G. Napier, who has rearranged the whole
of the Mollusca. Mr. David Grieve has kindly revised and added to the
Crustacea; and to the Messrs. Johnston of Montrose, and Dr. Wilson
Johnston of the Bengal service, I am indebted for some valuable
practical information respecting the salmon and the various modes of
taking it.

    W. S. O.

    _March 1, 1869._



CONTENTS.


                               CHAPTER I.

                                    PAGE
    THE OCEAN                          1
        Depth of the Sea               5
        Colour of the Ocean           11
        Phosphorescence               13
        Saltness of the Sea           15


    CHAPTER II.

    CURRENTS OF THE OCEAN             27
        Trade-winds                   28
        Gulf Stream                   31
        Storms                        32
        Tides                         35
        Polar Seas                    43
        Antarctic Seas                50


    CHAPTER III.

    LIFE IN THE OCEAN                 60


    CHAPTER IV.

    ZOOPHYTES                         68
        Foraminifera                  87
        Infusoria                     97


    CHAPTER V.

    POLYPIFERA                       116


    CHAPTER VI.

    CORALLINES                       119
        Tubiporinæ                   120
        Gorgoniadæ                   121
        Isidians                     124


    CHAPTER VII.

    ZOANTHARIA                       147
        Madreporidæ                  149
        Porites                      162
        Actiniaria                   181
        Minyadinians                 193


    CHAPTER VIII.

    ACALEPHÆ                         195
        Medusadæ                     213
        Rhizostoma                   219
        Vilelladæ                    229
        Ctenophora                   254


    CHAPTER IX.

    ECHINODERMATA                    259
        Asterias                     260
        Crinoidea                    270
        Echinidæ                     280


    MOLLUSCA.

    GENERAL DEFINITION               301


    CHAPTER X.

    MOLLUSCOIDA                      303
        Tunicata                     309
        Ascidians                    309


    CHAPTER XI.

    ACEPHALOUS MOLLUSCA              316


    CHAPTER XII.

    ACEPHALOUS MOLLUSCA              344
        Mytilidæ                     344


    CHAPTER XIII.

    CEPHALOUS MOLLUSCA               391
        Their Characteristics        391


    CHAPTER XIV.

    PULMONARY GASTEROPODS            396
        Limnæidæ                     397
        Buccinidæ                    428
        Purpura                      430
        Pterocera                    439


    CHAPTER XV.

    MOLLUSCOUS PTEROPODS             441


    CHAPTER XVI.

    CEPHALOPODOUS MOLLUSCA           445
        Tentaculifera                445
        Acetabula                    448


    CHAPTER XVII.
    CRUSTACEANS                      477
        General Definition           477
        Crabs and Crayfish           486
        Lobsters                     496


    CHAPTER XVIII.

    FISHES                           502

    CARTILAGINOUS FISHES             508
        Cyclostomata                 508
        Selachia                     510
        Sturiona                     524


    CHAPTER XIX.

    OSSEI, OR BONY FISHES            529
        Plectognathi                 529
        Lophobranchii                534
        Malacopterygii               536
        Abdominales                  560
        Acanthopterygians            590
        Pharyngeans                  596



ILLUSTRATIONS.


    PLATE                                                         PAGE

    I. THE ARGONAUT SAILING BEFORE THE WIND       (_Frontispiece_) 467

    II. SPONGE FISHING ON THE COAST OF SYRIA                        78

    III. CORAL FISHING ON THE COAST OF SICILY                      138

    IV. CORAL ISLAND IN THE POMOTOUAN ARCHIPELAGO                  169

    V. SEA ANEMONES (I.)                                           187

    VI. SEA ANEMONES (II.)                                         189

    VII. AGALMA RUBRA                                              239

    VIII. GALEOLARIA AURANTIACA                                    244

    IX. SEA-URCHINS                                                290

    X. FISHING FOR HOLOTHURIA                                      295

    XI. SYNAPTA DUVERNAEA                                          299

    XII. DREDGING FOR OYSTERS                                      374

    XIII. OYSTER PARKS ON LAKE FUSARO                              376

    XIV. PECTINIDÆ                                                 386

    XV. SPONDYLUS                                                  388

    XVI. ANODONTA                                                  340

    XVII. TRIDACNA GIGANTEA                                        338

    XVIII. VENUS AND CYTHEREA                                      336

    XIX. SOLENIDÆ (_Razor-fish_)                                   333

    XX. TEMPLE OF SERAPIS                                          330

    XXI. CONUS                                                     427

    XXII. CYPRÆADÆ                                                 421

    XXIII. VOLUTA                                                  426

    XXIV. CAPTURE OF A GIGANTIC CUTTLE-FISH                        462

    XXV. SHARK FISHING                                             520

    XXVI. STURGEON FISHING ON THE VOLGA                            528

    XXVII. FISHING FOR ELECTRICAL EELS                             539

    XXVIII. GREENLANDERS FISHING FOR HALIBUT                       551

    XXIX. THE HERRING FISHERY                                      580

    XXX. A ROMAN FEAST                                             593

    XXXI. FISHING FOR TUNNY IN PROVENCE                            598

    XXXII. FISHING FOR MACKEREL OFF THE CORNWALL COAST             601



THE OCEAN WORLD.



CHAPTER I.

THE OCEAN.

Ἄοιστον μὲν ὔδωρ--"The best of all things is
water."--PINDAR.


It is estimated that the sea covers nearly two-thirds of the surface of
the earth. The calculation, as given by astronomers, is as follows: The
surface of the earth is 31,625,625 ½ square miles, that portion
occupied by the waters being about 23,814,121 square miles, and that
consisting of continents, peninsulas, and islands, being 7,811,504
miles; whence it follows that the surface covered with water is to dry
land as 3·8 is to 1·2. The waters thus cover a little more than
seven-tenths of the whole surface. "On the surface of the globe,"
Michelet remarks, "water is the rule, dry land the exception."

Nevertheless, the immensity and depth of the seas are aids rather than
obstacles to the intercourse and commerce of nations; the maritime
routes are now traversed by ships and steamers conveying cargoes and
passengers equal in extent to the land routes. One of the features most
characteristic of the ocean is its continuity; for, with the exception
of inland seas, such as the Caspian, the Dead Sea, and some others, the
ocean is one and indivisible. As the poet says, "it embraces the whole
earth with an uninterrupted wave."

    Περὶ πᾶσαν θ' εἱλισσομένου
    χθόν' ἀκοιμἡτω ῥεύματι.

    ÆSCHYLUS in _Prometheus Vinctus_.

The mean depth of the sea is not very exactly ascertained, but certain
phenomena observed in the movement of tides are supposed to be incapable
of explanation without admitting a mean depth of three thousand five
hundred fathoms. It is true that a great number of deep-sea soundings
fall short of that limit; but, on the other hand, many others reach
seven or eight thousand. Admitting that three thousand fathoms
represents the mean depth of the ocean, Sir John Herschel finds that the
volume of its waters would exceed three thousand two hundred and
seventy-nine million cubic yards.

This vast volume of water is divided by geographers into five great
oceans: the Arctic, the Atlantic, Indian, Pacific, and Antarctic Oceans.

The Arctic Ocean extends from the Pole to the Polar Circle; it is
situated between Asia, Europe, and America.

The Atlantic Ocean commences at the Polar Circle and reaches Cape Horn.
It is situated between America, Europe, and Africa, a length of about
nine thousand miles, with a mean breadth of two thousand seven hundred,
covering a surface of about twenty-five million square miles, placed
between the Old World and the New. Beyond the Cape of Storms, as Cape
Horn may be truly called, it is only separated by an imaginary line from
the vast seas of the south, in which the waves, which are the principal
source of _tides_, have their birth. Here, according to Maury, the young
tidal wave, rising in the circumpolar seas of the south, and obedient to
the sun and moon, rolls on to the Atlantic, and in twelve hours after
passing the parallel of Cape Horn is found pouring its flood into the
Bay of Fundy, whence it is projected in great waves across the Atlantic
and round the globe, sweeping along its shores and penetrating its gulfs
and estuaries, rising and falling in the open sea two or three feet, but
along the shore having a range of ten or twelve feet. Sometimes, as at
Fundy on the American coast; at Brest on the French coast; and Milford
Haven, and the mouth of the Severn in the Bristol Channel, rising and
falling thirty or forty feet, "impetuously rushing against the shores,
but gently stopping at a given line, and flowing back to its place when
the word goes forth, 'Thus far shalt thou go, and no farther.' That
which no human power can repel, returns at its appointed time so
regularly and surely, that the hour of its approach and the measure of
its mass may be predicted with unerring certainty centuries beforehand."

The Indian Ocean is bounded on the north by Asia, on the west by Africa,
on the east by the peninsula of Molucca, the Sunda Isles, and
Australia.

The Pacific, or Great Ocean, stretches from north to south, from the
Arctic to the Antarctic Circle, being bounded on one side by Asia, the
island of Sunda, and Australia; on the other by the west coast of
America. This ocean contrasts in a striking manner with the Atlantic:
the one has its greatest length from north to south, the other from east
to west; the currents of the Pacific are broad and slow, those of the
other narrow and rapid; the waves of this are low, those of the other
very high. If we represent the volume of water which falls into the
Pacific by one, that received by the Atlantic will be represented by the
figure 5. The Pacific is the calmest of seas, and the Atlantic Ocean is
the most stormy.

The Antarctic Ocean extends from the Antarctic Polar Circle to the South
Pole.

It is remarkable that one half of the globe should be entirely covered
with water, whilst the other contains less of water than dry land.
Moreover, the distribution of land and water, if, in considering the
germ of the oceanic basins, we compare the hemispheres separated by the
Equator and the northern and southern halves of the globe, is found to
be very unequal.

Oceans communicate with continents and islands by coasts, which are said
to be scarped when a rocky coast makes a steep and sudden descent to the
sea, as in Brittany, Norway, and the west coast of the British Islands.
In this kind of coast certain rocky indentations encircle it, sometimes
above, sometimes under water, forming a labyrinth of islands, as at the
Land's End, Cornwall, where the Scilly Islands form a compact group of
from one to two hundred rocky islets, rising out of a deep sea; or in
the case of the Channel, on the opposite coast of France, where the
coast makes a sudden descent, forming steep cliffs and leaving an open
sea. The coast is said to be flat when it consists of soft argillaceous
soil descending to the shore with a gentle slope. Of this description of
coast there are two, namely, sandy beaches, and hillocks or dunes.

       *       *       *       *       *

What is the average depth of the sea? It is difficult to give an exact
answer to this question, because of the great difficulty met with in
taking soundings, caused chiefly by the deviations of submarine
currents. No reliable soundings have yet been made in water over five
miles in depth.

Laplace found, on astronomical consideration, that the mean depth of the
ocean could not be more than ten thousand feet. Alexander von Humboldt
adopts the same figures. Dr. Young attributes to the Atlantic a mean
depth of a thousand yards, and to the Pacific, four thousand. Mr. Airy,
the Astronomer Royal, has laid down a formula, that waves of a given
breadth will travel with certain velocities at a given depth, from which
it is estimated that the average depth of the North Pacific, between
Japan and California, is two thousand one hundred and forty-nine
fathoms, or two miles and a half. But these estimates fall far short of
the soundings reported by navigators, in which, as we shall see, there
are important and only recently discovered elements of error. Du Petit
Thouars, during his scientific voyage in the frigate _Venus_, took some
very remarkable soundings in the Southern Pacific Ocean: one, without
finding bottom at two thousand four hundred and eleven fathoms; another,
in the equinoctial region, indicated bottom at three thousand seven
hundred and ninety.

In his last expedition, in search of a north-west passage, Captain Ross
found soundings at five thousand fathoms. Lieutenant Walsh, of the
American Navy, reports a cast of the deep-sea lead, not far from the
American coast, at thirty-four thousand feet without bottom. Lieutenant
Berryman reported another unsuccessful attempt to fathom mid ocean with
a line thirty-nine thousand feet in length. Captain Denman, of H. M. S.
Herald, reported bottom in the South Atlantic at the depth of forty-six
thousand feet; and Lieutenant J. P. Parker, of the United States frigate
_Congress_, on attempting soundings near the same region, let go his
plummet, after it had run out a line fifty thousand feet long, as if the
bottom had not been reached. We have the authority of Lieutenant Maury
for saying, however, that "there are no such depths as these." The
under-currents of the deep sea have power to take the line out long
after the plummet has ceased to sink, and it was before this fact was
discovered that these great soundings were reported. It has also been
discovered that the line, once dragged down into the depths of the
ocean, runs out unceasingly. This difficulty was finally overcome by the
ingenuity of Midshipman Brooke. Under the judicious patronage of the
Secretary to the United States Navy, Mr. Brooke invented the simple and
ingenious apparatus (Fig. 1), by which soundings are now made, in a
manner which not only establishes the depth, but brings up specimens of
the bottom. The sounding-line in this apparatus is attached to a weighty
rod of iron, the lower extremity of which contains a hollow cup for the
reception of tallow or some other soft substance. This rod is passed
through a hole in a thirty-two pound spherical shot, being supported in
its position by slings A, which are hooked on to the line by the swivels
_a_. When the rod strikes the bottom, the tension on the line ceases,
the swivels are reversed, the slings B are thrown out of the hooks, the
ball falls to the ground, and the rod, released from its weight, is
easily drawn up, bringing with it portions of the bottom attached to the
greasy substance in the cup. By means of this apparatus, specimens of
the bottom have been brought up from the depth of four miles.

[Illustration: Fig. 1. Brooke's Sounding Apparatus.]

The greatest depth at which the bottom has been reached with this
plummet is in the North Atlantic between the parallels of thirty-five
and forty degrees north, and immediately south of the great bank of
rocks off Newfoundland. This does not appear to be more than twenty-five
thousand feet deep. "The basin of the Atlantic," says Maury, "according
to the deep-sea soundings in the accompanying diagram, is a long trough
separating the Old World from the New, and extending, probably, from
pole to pole. In breadth, it contrasts strongly with the Pacific Ocean.
From the top of Chimborazo to the bottom of the Atlantic, at the deepest
place yet reached by the plummet in that ocean, the distance in a
vertical line is nine miles."

"Could the waters of the Atlantic be drawn off, so as to expose to view
this great sea gash which separates continents, and extends from the
Arctic to the Antarctic Seas, it would present a scene the most rugged,
grand, and imposing; the very ribs of the solid earth with the
foundations of the sea would be brought to light, and we should have
presented to us in one view, in the empty cradle of the ocean, 'a
thousand fearful wrecks,' with the array of 'dead men's skulls, great
anchors, heaps of pearls, and inestimable stones,' which, in the poet's
eye, lie scattered on the bottom of the sea, making it hideous with the
sight of ugly death."

The depth of the Mediterranean is comparatively inconsiderable. Between
Gibraltar and Ceuta, Captain Smith estimates the depth at about five
thousand seven hundred feet, and from one to three thousand in the
narrower parts of the straits. Near Nice, Saussure found bottom at three
thousand two hundred and fifty. It is said that the bottom is shallower
in the Adriatic, and does not exceed a hundred and forty feet between
the coast of Dalmatia and the mouths of the Po.

The Baltic Sea is remarkable for its shallow waters, its maximum rarely
exceeding six hundred feet.

It thus appears that the sea has similar inequalities to those observed
on land; it has its mountains, valleys, hills, and plains.

The Deep-sea Sounding Apparatus of Lieutenant Brooke has already
furnished some very remarkable results. Aided by it, Dr. Maury has
constructed his fine orographic map of the basin of the Atlantic, which
is probably as exact as the maps which represent Africa or Australia.
Dr. Maury has also published many charts, giving the depths of the
ocean, the substance of which is given in the accompanying map, which
represents the configuration of the Atlantic up to the tenth degree of
south latitude, not in figures, as in Dr. Maury's charts, but in tints;
diagonal lines from right to left, representing the shores of both
hemispheres, indicate a depth of less than a thousand fathoms; from left
to right, indicate bottom at one thousand to two thousand; horizontal
lines, two to three thousand fathoms; cross lines show an average depth
of three to four thousand fathoms; finally, the perpendicular lines
indicate a depth of four thousand fathoms and upwards. Solid black
indicates continents and islands; waving lines, surrounding both
continents at a short distance from the shore, indicate the sands which
surround the coast line at a little distance from the shore.

[Illustration: Fig. 2. Chart of the Atlantic Ocean.]

       *       *       *       *       *

The question may be asked, what useful purpose is served by taking
soundings at great depths? To this we may quote the answer of Franklin
to a question of similar tendency, addressed to aeronauts--"What purpose
is served by the birth of a child?" Every fact in physics is interesting
in itself; it forms a rallying point, round which, sooner or later,
others will meet, in order to establish some useful truth; and the
importance of making and recording deep-sea soundings is established by
the successful immersion of the transatlantic telegraph.

At the bottom of the Atlantic there exists a remarkable plateau,
extending from Cape Race in Newfoundland, to Cape Clear in Ireland, a
distance of over two thousand miles, with a breadth of four hundred and
seventy miles: its mean depth along the whole route is estimated at two
miles to two miles and a half. It is upon this telegraphic plateau, as
it has been called, that the attempt was made to lay down the cable in
1858, and it is on it that the enterprise has been so successfully
completed, during the year 1866. Tubular annelids, capable of boring
into all organic substances, are native to this plateau, and have
materially assisted in destroying the electric cable. The surface of the
plateau had been previously explored by means of Brooke's apparatus, and
the bottom was found to be composed chiefly of microscopic calcareous
shells (_Foraminifera_), and a few siliceous shells (_Diatomaceæ_).
These delicate and fragile shells, which seemed to strew the bottom of
the sea, in beds of great thickness, were brought up by the sounding-rod
in a state of perfect preservation, which proves that the water is
remarkably quiet in these depths,--an inference which is fully borne out
by the condition in which the cable of 1858 was found, when picked up in
1866.

[Illustration: Fig. 3. Section of the Atlantic, showing its depth and
the position of the Atlantic Telegraph.]

The first exploration of this plateau was undertaken by the American
brig _Dolphin_, which took a hundred soundings one hundred miles from
the coast of Scotland, afterwards taking the direction of the Azores, to
the north of which bottom was found, consisting of chalk and yellow
sand, at nine thousand six hundred feet. To the south of Newfoundland,
the depth was found to be sixteen thousand five hundred feet. In 1856,
Lieutenant Berryman, of the American steamer _Arctic_, completed a line
of soundings from St. John, Newfoundland, to Valentia, off the Irish
coast, and in 1857, Lieutenant Dayman, of the English steamship
_Cyclops_, repeated the same operation: this last line of soundings,
the result of which is represented in the accompanying section, differed
slightly from that followed by Lieutenant Berryman.

In the Gulf of Mexico, the depth does not seem to exceed seven thousand
feet; the Baltic does not in any place exceed eleven hundred. The depth
of the Mediterranean is, as we have said, very variable. At Nice,
according to Horace de Saussure, the average depth is three thousand
three hundred feet. Between the Dalmatian coast and the mouth of the Po,
bottom is found at a hundred and forty feet. Captain Smith found
soundings at from one thousand to nine thousand feet in the Straits of
Gibraltar, and at ten thousand feet between Gibraltar and Ceuta, where
the breadth exceeds sixteen miles. Between Rhodes and Alexandria, the
greatest depth is ten thousand feet. Between Alexandria and Candia it is
ten thousand three hundred. A hundred and twenty miles east of Malta it
is fifteen thousand. The peculiar form of the Mediterranean has led to
its being compared to a vast inverted tunnel.

The Arctic Ocean has, probably, no great depth. Hence salt water,
following the general law of contracting as it is cooled until it
freezes, no ice can be formed on its surface till the temperature has
fallen through its entire depth nearly to freezing point, when the
entire mass is consolidated into pack-ice. According to Baron Wrangel,
the bottom of the glacial sea, on the north coast of Siberia, forms a
gentle slope, and, at the distance of two hundred miles from the shore,
it is still only from ninety to a hundred feet. Nevertheless, in
Baffin's Bay, Dr. Kane made soundings at eleven thousand six hundred
feet.

The inequalities of the basin of the Pacific Ocean are, comparatively,
unknown to us. The greatest depth observed by Lieutenant Brooke in the
great ocean is two thousand seven hundred fathoms, which he found in
fifty-nine degrees north latitude and one hundred and sixty-six degrees
east longitude. Applying the theory of waves to the billows propelled
from the coast of Japan to California, during the earthquake of the 23rd
of December, 1854, Professor Bache calculated that the mean depth of
this part of the Pacific is fourteen thousand four hundred feet. In the
Pacific Ocean, latitude sixty degrees south and one hundred and sixty
degrees east longitude, he found soundings at fourteen thousand six
hundred feet--about two miles and a half. Another cast of the lead in
the Indian Ocean was made in seven thousand and forty fathoms, but
without bringing up any soil from the bottom. Among the fragments
brought up from the bottom of the Coral Sea, a remarkable absence of
calcareous shells was noted, whilst the siliceous fragments of sponges
were found in great quantities. Other soundings made in the Pacific, at
a depth of four or five miles, were examined by Ehrenberg, who found a
hundred and thirty-five different forms of infusoria represented, and
among them twenty-two species new to him. Generally speaking, the
composition of the infusoria of the Atlantic are calcareous; those of
the Pacific, siliceous. These animalcules draw from the sea the mineral
matter with which it is charged--that is, the lime or silica which form
their shell. These shells accumulate after the death of the animal, and
form the bottom of the ocean. The animals construct their habitations
near the surface; when they die, they fall into the depths of the ocean,
where they accumulate in myriads, forming mountains and plains in mid
ocean. In this manner, we may remark, _en passant_, many of the existing
continents had their birth in geological times. The horizontal beds of
marine deposits, which are called _sedimentary rocks_, and especially
the cretaceous rocks and calcareous beds of the Jurassic and Tertiary
periods, all result from such remains.[1]

The sea level is, in general, the same everywhere. It represents the
spherical form of our planet, and is the basis for calculating all
terrestrial heights; but many gulfs and inland seas open on the east are
supposed to be exceptions to this rule: the accumulation of waters,
pressed into these receptacles by the general movement of the sea from
east to west, it is alleged, may pile up the waters, in some cases, to a
greater height than the general level.

It had long been admitted, on the faith of inexact observation, that the
level of the Red Sea was higher than that of the Mediterranean. It has
also been said that the level of the Pacific Ocean at Panama is higher
by about forty inches than the mean level of the Atlantic at Chagres,
and that, at the moment of high water, this difference is increased to
about thirteen feet, while at low it is over six feet in the opposite
direction. This has been proved, so far as the evidence goes, to be
error in what concerns the difference in level of the Red Sea and
Mediterranean; and the opening of the Suez Canal, which is near at hand,
will probably furnish still more convincing proofs. Recent soundings
show that the mean level of the Pacific and Atlantic Oceans are
identical.

       *       *       *       *       *

It has been calculated that all the waters of the several seas gathered
together would form a sphere of fifty or sixty leagues in diameter, and,
supposing the surface of the globe perfectly level, that these waters
would submerge it to the depth of more than six hundred feet. Again,
admitting the mean depth of the sea to be thirteen thousand feet, its
estimated contents ought to be nearly two thousand two hundred and fifty
millions of cubic miles of water; and, if the sea could be imagined to
be dried up, all the sewers of the earth would require to pour their
waters into it for forty thousand years, in order to fill the vast
basins anew.

       *       *       *       *       *

If we could imagine the entire globe to be divided into one thousand
seven hundred and eighty-six parts by weight, we should find
approximately, according to Sir John Herschel, that the total weight of
the oceanic waters is equivalent to one of these parts.

The specific weight of sea water is a little above that of fresh water,
the proportion being as a thousand to a thousand and twenty-seven. The
Dead Sea, which receives no fresh water into its bosom to maintain
itself at the same level as other seas, acquires a higher degree of
saltness, and is equal to a thousand and twenty-eight. The specific
gravity of sea water is about the same as the milk of a healthy woman.

       *       *       *       *       *

The colour of the sea is continually varying, and is chiefly caused by
filtration of the solar rays. According to the testimony of the majority
of observers, the ocean, seen by reflection, presents a fine azure blue
or ultramarine (_cæruleum mare_). When the air is pure and the surface
calm this tint softens insensibly, until it is lost and blended with the
blue of the heavens. Near the shore it becomes more of a green or
glaucus, and more or less brilliant, according to circumstances. There
are some days when the ocean assumes a livid aspect, and others when it
becomes a very pure green; at other times, the green is sombre and sad.
When the sea is agitated, the green takes a brownish hue. At sunset, the
surface of the sea is illumined with tints of every hue of purple and
emerald. Placed in a vase, sea water appears perfectly transparent and
colourless. According to Scoresby, the Polar seas are of brilliant
ultramarine blue. Castaz says of the Mediterranean, that it is celestial
blue, and Tuckey describes the equinoctial Atlantic as being of a vivid
blue.

Many local causes influence the colours of marine waters, and give them
certain decided and constant shades. A bottom of white sand will
communicate a greyish or apple-green colour to the water, if not very
deep; when the sand is yellow, the green appears more sombre; the
presence of rocks is often announced by the deep colour which the sea
takes in their vicinity. In the Bay of Loango the waters appear of a
deep red, because the bottom is there naturally red. It appears white in
the Gulf of Guinea, yellow on the coast of Japan, green to the west of
the Canaries, and black round the Maldive group of islands. The
Mediterranean, towards the Archipelago, sometimes becomes more or less
red. The White and Black Seas appear to be named after the ice of the
one and the tempests to which the other is subject.

At other times, coloured animalcules give to the water a particular
tint. The Red Sea owes its colour to a delicate microscopic algæ
(_Trychodesmium erythræum_), which was subjected to the microscope by
Ehrenberg; but other causes of colouration are suggested. Some
microscopists maintain that it is imparted by the shells and other
remains of infusoria; others ascribe the colour to the evaporation which
goes on unceasingly in that riverless district, producing salt rocks on
a great scale all round its shores. In the same manner sea water,
concentrated by the action of the solar rays in the salt marshes of the
south of France, when they arrive at a certain stage of concentration
take a fine red colour, which is due to the presence of some red-shelled
animalcules which only appear in sea water of this strength. The saline
lakes on the Great Thibetian water sheds are due to this cause.
Strangely enough, these minute creatures die when the waters attain
greater density by further concentration, and also if it becomes weaker
from the effects of rain.

       *       *       *       *       *

Navigators often traverse long patches of green, red, white, or yellow
coloured water, all of which are due to the presence of microscopic
crustaceans, medusæ, zoophytes, and marine plants; the Vermilion Sea on
the Californian coast is entirely due to the latter cause.

       *       *       *       *       *

The phenomenon known as _Phosphorescence of the Sea_ is due to analogous
causes. This wonderful sight is observable in all seas, but is most
frequent in the Indian Ocean, the Arabian Gulf, and other tropical seas.
In the Indian Ocean, Captain Kingman, of the American ship _Shooting
Star_, traversed a zone twenty-three miles in length so filled with
phosphorescent animalcules that at seven hours forty-five minutes the
water was rapidly assuming a white, milky appearance, and during the
night it presented the appearance of a vast field of snow. "There was
scarcely a cloud in the heavens," he continues, "yet the sky, for about
ten degrees above the horizon, appeared as black as if a storm were
raging; stars of the first magnitude shone with a feeble light, and the
'Milky Way' of the heavens was almost entirely eclipsed by that through
which we were sailing." The animals which produced this appearance were
about six inches long, and formed of a gelatinous and translucent
matter. At times, the sea was one blaze of light, produced by countless
millions of minute globular creatures, called _Noctilucæ_. The motion of
a vessel or the plash of an oar will often excite their lucidity, and
sometimes, after the ebb of tide, the rocks and seaweed of the coast are
glowing with them. Various other tribes of animals there are which
contribute to this luminous appearance of the sea. M. Peron thus
describes the effect produced by _Pyrosoma Atlanticum_, on his voyage to
the Isle of France: "The wind was blowing with great violence, the night
was dark, and the vessel was making rapid way, when what appeared to be
a vast sheet of phosphorus presented itself floating on the waves, and
occupying a great space ahead of the ship. The vessel having passed
through this fiery mass, it was discovered that the light was occasioned
by animalcules swimming about in the sea at various depths round the
ship. Those which were deepest in the water looked like red-hot balls,
while those on the surface resembled cylinders of red-hot iron. Some of
the latter were caught: they were found to vary in size from three to
seven inches. All the exterior of the creatures bristled with long thick
tubercles, shining like so many diamonds, and these seemed to be the
principal seat of their luminosity. Inside also there appeared to be a
multitude of oblong narrow glands, exhibiting a high degree of
phosphoric power. The colour of these animals when in repose is an opal
yellow, mixed with green; but, on the slightest movement, the animal
exhibits a spontaneous contractile power, and assumes a luminous
brilliancy, passing through various shades of deep red, orange, green,
and azure blue."

The phosphorescence of the sea is a spectacle at once imposing and
magnificent. The ship, in plunging through the waves, seems to advance
through a sea of red and blue flame, which is thrown off by the keel
like so much lightning. Myriads of creatures float and play on the
surface of the waves, dividing, multiplying, and reuniting, so as to
form one vast field of fire. In stormy weather the luminous waves roll
and break in a silvery foam. Glittering bodies, which might be taken for
fire-fishes, seem to pursue and catch each other--lose their hold, and
dart after each other anew. From time immemorial, the phosphorescence of
the sea has been observed by navigators. The luminous appearance
presents itself on the crest of the waves, which in falling scatters it
in all directions. It attaches itself to the rudder and dashes against
the bows of the vessel. It plays round the reefs and rocks against which
the waves beat, and on silent nights, in the tropics, its effects are
truly magical. This phosphorescence is due chiefly to the presence of a
multitude of mollusks and zoophytes which seem to shine by their own
light; they emit a fluid so susceptible of expansion, that in the zigzag
movement pursued they leave a luminous train upon the water, which
spreads with immense rapidity. One of the most remarkable of these
minute mollusks is a species of _Pyrosoma_, a sort of mucous sac of an
inch long, which, thrown upon the deck of a ship, emits a light like a
rod of iron heated to a white heat. Sir John Herschel noted on the
surface of calm water a very curious form of this phosphorescence; it
was a polygon of rectilinear shape, covering many square feet of
surface, and it illuminated the whole region for some moments with a
vivid light, which traversed it with great rapidity.

The phosphorescence of the sea may also result from another cause. When
animal matter is decomposed, it becomes phosphorescent. The bodies of
certain fishes, when they become a prey to putrefaction, emit an intense
light. MM. Becquerel and Breschet have noted fine phosphorescent effects
from this cause in the waters of the Brenta at Venice. Animal matter in
a state of decomposition, proceeding from dead fish which floats on the
surface of ponds, is capable of producing large patches of oleaginous
matter, which, piled upon the water, communicates to a considerable
extent the phosphorescent aspect.

       *       *       *       *       *

Whatever may be the case elsewhere, there are local causes which affect
the colour of the waters in certain rivers, and even originate their
names. The Guaïnia, which with the Casiquaire forms the Rio Negro, is of
a deep brown, which scarcely interferes with the limpidity of its
waters. The waters of the Orinoco and the Casiquaire have also a
brownish colour. The Ganges is of a muddy brown, while the Djumna, which
it receives, is green or blue. The whitish colour belongs to the Rio
Bianco, or White River, and to many other rivers. The Ohio in America,
the Torgedale, the Goetha, the Traun at Ischl, and most of the Norwegian
rivers, are of a delicate limpid green. The Yellow River and the Blue
River in China are distinguished by the characteristic tint of their
waters. The Arkansas, the Red River, and the Lobregat in Catalonia, are
remarkable for their red colour, which, like the Dart and other English
rivers, they owe to the earth over which they flow, or which their
waters hold in suspension.

       *       *       *       *       *

The water of the sea is essentially _salt_, of a peculiar flavour,
slightly acrid and bitter, and a little nauseous. It has an odour
perfectly _sui generis_, and is slightly viscous. In short, it includes
a great number of mineral salts and some other compounds, which give it
a very disagreeable taste, and render it unfit for domestic use. It
contains nearly all the soluble substances which exist on the globe, but
principally chloride of sodium, or marine salt, and sulphate of
magnesia, of potassium, and of lime.

Pure water is produced by a combination of one volume of oxygen and of
two volumes of hydrogen, or in weight, 100 oxygen and 12·50 hydrogen.
Sea water is composed of the same; but we find there, besides, other
elements, the presence of which chemistry reveals to us. In 1000 grains
of sea water the following ingredients are found:--

    Water                             962·0
    Chloride of sodium                 27·1
    Chloride of magnesium               5·4
    Chloride of potassium               0·4
    Bromide of magnesia                 0·1
    Sulphate of magnesia                1·2
    Sulphate of lime                    0·8
    Carbonate of lime                   0·1
              Leaving a residuum of     2·9
                                      -----
                                       1000
                                      =====

consisting of sulphuretted hydrogen, hydrochlorate of ammonia, iodine
iron, copper, and even silver in various quantities and proportions,
according to the locality of the specimen. In examining the plates of
copper taken from the bottom of a ship at Valparaiso, which had been
long at sea, distinct traces of silver were found deposited by the sea.
Finally, we find dissolved in the ocean a peculiar mucus, which seems of
a mixed animal and vegetable nature, and is evidently organic matter
proceeding from the successive decomposition of the innumerable
generations of animals which have disappeared since the beginning of the
world. This matter has been described by the Count Marsigli, who
designates it sometimes under the name of _glu_, and sometimes as an
_unctuosity_. It is the "ooze" of marine surveyors, and consists chiefly
of carbonate of lime, ninety per cent. of which is formed of minute
animal organisms. Its mealy adhesiveness results from the pressure of
the superimposed water. The numerous salts which exist in the sea can
neither be deposited in its bed, nor exhaled with the vapour, to be
again poured upon the soil in showers of rain. Particular agents retain
these salts in solution, transform them, and prevent their accumulation.
Hence sea water always maintains a certain degree of saltness and
bitterness, and the ocean continues to present the chemical characters
which it has exhibited in all times, varying only in certain localities
where more or less fresh water is poured into the sea basin from rivers:
thus the saltness of the Mediterranean is greater than that of the
ocean, probably because it loses more water by evaporation than it
receives from its fresh-water affluents. For the opposite reason, the
Black and the Caspian Seas are less charged with these salts. The Dead
Sea is so strongly impregnated with salt that the body of a man floats
on its surface without sinking, like a piece of cork upon fresh water.
The supposed cause is excessive evaporation and the absence of rivers of
any importance.

The saltness of the sea seems to be generally less towards the poles
than the equator; but there are exceptions to this law. In the Irish
Channel, near the Cumberland coast, the water contains salt equal to the
fortieth of its weight; on the coast of France, it is equal to one
thirty-second; in the Baltic, it is equal to a thirtieth; at Teneriffe,
a twenty-eighth; and off the coast of Spain, to a sixteenth. Again, in
many places the sea is less salt at the surface than at the bottom. In
the Straits of the Dardanelles, at Constantinople, the proportion is as
seventy-two to sixty-two. In the Mediterranean, it is as thirty-two to
twenty-nine. It is also stated that as the salt increases at a certain
depth, the water becomes less bitter. At the mouth of the great rivers
it is scarcely necessary to add that the water is always less saline
than on shores which receive no supplies of fresh water; the same remark
applies to sea water in the vicinity of polar ice, the melting of which
is productive of much fresh water. A recent analysis of the water of the
Dead Sea by M. Roux gives about two pounds of salt to one gallon of
water. No mineral water, if we except that of the Salt Lake of Utah, is
so largely impregnated with saline substances; the quantity of bromide
of magnesia is 0·35 grammes to the litre. The water of the Dead Sea is,
according to these proportions, the richest natural depository of
bromide, which it might be made to furnish abundantly. The waters of the
great Lake of Utah and Lake Ourmiah in Persia are both highly saline. In
Lake Ourmiah, as in the Dead Sea, the proportion of salt is six times
greater than in the ocean. Many of our fresh-water lakes were probably
salt originally, but have by degrees lost their saline properties by the
mingling of their waters with those of the rivers which traverse or flow
into them. Among the lakes which appear to have been divested of their
saline properties may be mentioned the great lakes of Canada and the Sea
of Baikal, in all of which seals and other marine animals are still
found, which have become acclimatized as the water gradually became
fresh.

The saltness of sea water increases its density, and at the same time
its buoyancy, thus adapting it for bearing ships and other burdens on
its bosom; moreover, to abbreviate slightly Dr. Maury's remark, "the
brine of the ocean is the ley of the earth." From it the sea derives
dynamical power, and its currents their main strength. It is the salt of
the sea that imparts to its waters those curious anomalies in the laws
of freezing and of thermal dilatation, that assist the rays of heat to
penetrate its bosom; the salts of the sea invest it with adaptations
which fresh water could not possess. In the latter case, the maximum
density would be thirty-nine degrees two seconds F. instead of
twenty-seven degrees two seconds F., when the dynamical force of the sea
would be insufficient to put the Gulf Stream in motion. Nor could it
regulate those climates we call marine.

       *       *       *       *       *

We have said that sea water contains nearly all the soluble substances
which exist in the globe. Nevertheless its exhalation is comparatively
pure. "The water which evaporates from the sea," says Youman, in his
"Chemistry," "is nearly pure, containing but very minute traces of
salts. Falling as rain upon the land, it washes the soil, percolates
through the rocky layers, and becomes charged with saline substances,
which are borne seaward by the returning currents. The ocean, therefore,
is the great depository of all substances that water can dissolve and
carry down from the surface of the continents; and, as there is no
channel for their escape, they would constantly accumulate, were it not
for the creatures which inhabit the seas, and utilize the material thus
brought within their reach." These substances are chloride of sodium or
marine salt, sulphates of magnesia, potassa, lime, and other substances
which the water of various seas is found to contain.

In the year 1847, I made an analysis of water taken a few leagues from
the coast at Havre, which gave the following result, from one litre (1
pint·760773):--[2]

                                                         Grammes.
    Chloride of sodium                                    25·704
    Chloride of magnesium                                  2·905
    Sulphate of magnesia                                   2·462
    Sulphate of lime                                       1·210
    Sulphate of potassa                                    0·094
    Carbonate of lime                                      0·132
    Silicate of soda                                       0·017
    Bromide of sodium                                      0·103
    Bromide of magnesium                                   0·030
    Oxide of iron, carbonate and phosphate of magnesia,}   Only
      and oxide of manganese                           }   traces.
                                                          ------
                                                          32·657
                                                          ======

The water of the Mediterranean contains more salts than that of the
ocean.

The following are, according to M. Usiglio, who was one of a commission
sent to examine the different kinds of salt water in the south of
France, the component parts of one hundred gallons of Mediterranean
water:--

                                     lbs.
    Chloride of sodium            29·524
    Chloride of potassium          0·405
    Chloride of magnesium          3·219
    Sulphate of magnesia           2·477
    Chloride of calcium            6·080
    Sulphate of lime               1·557
    Carbonate of lime              0·114
    Bromide of sodium              0·356
    Protoxide of iron              0·003
                                  ------
                    Total         43·735
                                  ======

We conclude, from the quantity of sea salt contained in the water of the
ocean, that, if it were spread over the surface of the globe, it would
form a layer of more than thirty feet in height.

The salt contained in sea water gives it a greater density than fresh
water; its average specific weight is 1.027. The density of the water of
the Mediterranean is, according to M. Usiglio, 1.025 when at the
temperature of seventy degrees. But the saltness of the sea varies very
much under the influence of a great many local circumstances, among
which we must count principally currents, winds favourable to
evaporation, rivers coming from the continents, &c.

It has been remarked that the sea is less salt towards the poles than at
the equator; that the saltness increases, in general, with the distance
from land, and the depth of the water; that the interior seas, such as
the Baltic, the Black Sea, the White Sea, the Sea of Marmora, and the
Yellow Sea, are less salt than the ocean. The Mediterranean is an
exception to this last rule; it is, as we have seen, salter than the
ocean. This difference is explained by the fact that the quantity of
fresh water brought into it by rivers is less than that lost by
evaporation. The Mediterranean must therefore grow salter with time,
unless its water is discharged into the ocean by a counter current,
which would run under the current coming from the Atlantic by the
Straits of Gibraltar.

The Black Sea, on the contrary, the water of which has a density of only
1.013, receives from rivers more fresh water than it loses by
evaporation. The saltness of this interior sea is only half as intense
as that of the ocean.

The Sea of Azov and the Caspian Sea are still less salt than the Black
Sea.

The following table shows the relative composition of the water in these
three interior seas:--

  +--------------------------+--------------+--------------+--------------+
  |                          |  Black Sea.  | Sea of Azov. | Caspian Sea. |
  | In 100 Gallons of Water. |   Density    |   Density    |   Density    |
  |                          |    1·013     |    1·009.    |    1·005.    |
  +--------------------------+--------------+--------------+--------------+
  | Chloride of sodium       |   14·0195    |    9·6583    |    3·6731    |
  | Chloride of potassium    |    9·1892    |    0·1279    |    0·0761    |
  | Chloride of magnesium    |    1·3045    |    0·8870    |    0·6324    |
  | Sulphate of magnesia     |    1·4704    |    0·7642    |    1·2389    |
  | Sulphate of lime         |    0·1047    |    0·2879    |    0·4903    |
  | Bicarbonate of magnesia  |    0·2086    |    0·1286    |    0·0129    |
  | Bicarbonate of lime      |    0·3646    |    0·0221    |    0·1705    |
  | Bromide of magnesium     |    0·0052    |    0·0035    |    traces    |
  |                          +--------------+--------------+--------------+
  |                          |   17·6663    |   11·8795    |    6·2942    |
  +--------------------------+--------------+--------------+--------------+

In lakes without any outlet, as the Dead Sea and the Lake of Ural, the
degree of saltness is considerably augmented. Numerous experiments have
proved that the water of the Dead Sea is six times salter than that of
the ocean. MM. Boutron and O'Henry analysed, in April, 1850, after the
rainy season, some water of the Dead Sea, taken at about two leagues
from the mouth of the Jordan; its density was then 1·10.

The saltness of sea water makes it more fitted to float ships, because
its density is increased by the salts which are dissolved in it. Besides
this, these salts contribute to prevent the water becoming contaminated
with decomposed organic matter.

By the table representing the composition of the water of the ocean and
of that of the Mediterranean, we see that salts of lime and potassium,
as well as iodine and silica, are only found in infinitely small
quantities. Nevertheless, the lime and silica contained in the sea water
are of very great importance; for these quantities, which appear to us
so small in the table of a chemical analysis, become enormous in the
entire extent of the ocean. The marine plants take in the lime, the
silica, the potassa, and the iodides which are dissolved in the sea
water; these mineral substances enter into their textures. It is from
the carbonate of lime and silica that the marine animals form their
solid covering, their shell or carapace. The infusoria make use of the
lime, silica, and potassa for the same purpose. It is by the life and
habits of the polypi that we explain those _Coral Islands_ found in the
sea, the existence of which has been a subject of much astonishment,
and ought, therefore, to find a place in this chapter.

The Pacific and Indian Oceans are studded with islands in a state of
formation, which owe their origin to the polypi and corallines. These
zoophytes extract from the sea water the lime and silicium which are
found there in the state of soluble salts. In order to grow and develop,
they must be continually under water. They are constantly producing
calcareous deposits; these deposits rise rapidly, and at last reach the
surface of the water. Then the seaweed and rubbish of all kinds that the
sea carries along with it, arrested by these emerged masses, cover them
with a layer of fertile soil; which is soon covered with vegetation, as
the birds and the waves bring seeds thither.

The Coral Islands of the Pacific, which are described in another
chapter, are formed in this manner.

Besides the substances named, sea water also contains, in
infinitesimally small quantities, metals, such as iron, copper, lead and
silver. The old copper collecting round the keels of ships sometimes so
much silver that it has been thought worth extracting! A curious
calculation has been attempted, based on the age of ships and the
distance they have gone during all their voyages, to show that the sea
contains in solution two million tons of silver.[3]

The question has often been asked, whence comes the salt and other
substances held in solution in sea water? If our readers will turn back
to the first few pages of "The World before the Deluge," they will
better understand the very simple geological explanation that we are
going to give of the origin of different substances dissolved in sea
water.

In the first stage of our planet, before the watery vapours contained in
the primitive atmosphere were condensed, and before they had begun to
fall on the earth in the form of boiling rain, the shell of the earth
contained an infinite variety of heterogeneous mineral substances, some
soluble in water, others not. When rain fell on the burning surface for
the first time, the waters became charged with all the soluble
substances, which were reunited and afterwards deposited, accumulating
in the large depressions of the soil. The seas of the primitive globe
were thus formed of rain water, holding in solution all that the earth
had given up, collected in large basins. Chloride of sodium, sulphates
of soda, magnesia, potassium, lime, and silica, in the form of soluble
silicate; in a word, every soluble matter that the primitive globe
contained formed part of the mineral contingent of this water. If we
reflect that through all time up to the present day none of the general
laws of nature have changed--if we consider that the soluble substances
contained in the water of the primitive seas have remained there, and
that the fresh water of the rivers constantly replaces the water which
disappears by evaporation--we have the true explanation of the saltness
of sea water. "It is a very simple theory, it is true," adds M. Figuier,
"but one that we have found nowhere, and the responsibility of which we
therefore claim. The chloride of sodium is by no means the only
substance dissolved in sea water. It contains, besides, many other
mineral substances: in short, every _soluble salt_ on the face of the
globe, and, along with them, portions of different metals in infinitely
small quantities."

The mean temperature of the surface of the sea is nearly the same as the
atmosphere, so long as no currents of heat or cold interpose their
perturbing influence. In the neighbourhood of the Tropics, it appears
that the surface of the water is slightly warmer than the ambient air,
but experiments on the temperature of the sea from the surface to the
bottom reveal, according to our author,[4] "some evidence which
establishes a curious law. In very deep water a perfectly uniform
temperature of four degrees below zero prevails, which corresponds, as
physics have established, to the maximum density of water. Under the
Equator this temperature exists at the depth of seven thousand feet. In
the Polar regions, where water is colder at the surface, this
temperature is maintained at four thousand six hundred feet. The
isothermal lines of four degrees form a line of demarcation between the
Zones, where the surface of the sea is colder, and those where it is
warmer than the bed of four degrees below zero." This is more clearly
shown in Fig. 4, which represents a section of the ocean, the curved
line which touches two points at the surface indicating the depths where
the temperature is constantly fixed at four degrees.

Dr. Maury's account of this phenomenon is asserted with less confidence.
The existence of an _isothermal floor_ of the ocean, as he calls it,
was first suggested by the observations of Kotzebue, Admiral Beechey,
and Sir James C. Ross. "Its temperature, according to Kotzebue, is
thirty-six degrees Fahr., or four degrees Cent.; the depth of this bed,
of invariable and uniform temperature, is twelve hundred fathoms at the
Equator; thence it gradually rises to the parallel of about fifty-six
degrees north and south, when it crops out, and there the temperature of
the sea from top to bottom is conjectured to be permanent at thirty-six
degrees. The place of this outcrop, no doubt, shifts with the seasons,
vibrating north and south, after the manner of the Calm belts.
Proceeding onwards to the Frigid zones, this aqueous stratum of an
unchanging temperature dips again, and continues to incline till it
reaches the Poles, at the depth of seven hundred and fifty fathoms; so
that on the equatorial side of the outcrop the water above the
isothermal floor is the warmer, but in Polar seas the supernatant water
is the colder."

[Illustration: Fig 4. Thermal Lines of equal Temperature.]

       *       *       *       *       *

In the saline properties of sea water Maury discovers one of the
principal forces from which currents in the ocean proceed. "The brine of
the ocean is the ley of the earth," he says; "from it the sea derives
dynamical powers, and its currents their main strength. Hence, to
understand the dynamics of the ocean, it is necessary to study the
effects of their saltness upon the equilibrium of the waves. Why is the
sea made salt? It is the salts of the sea that impart to its waters
those curious anomalies in the laws of freezing and of thermal
dilatation. It is the salts of the sea that assist the rays of heat to
penetrate its bosom." The circulation of the ocean is indispensable to
the distribution of temperature--to the maintenance of the
meteorological and climatic conditions which rule the development of
life; and this circulation could not exist--at least, the character of
its waters would be completely changed--if they were fresh in place of
salt. "Let us imagine," says M. Julien, "that the sea, now entirely
composed of fresh water, of one uniform temperature from the Pole to the
Equator, and from the surface to its greatest depths; the solar heat
would penetrate the liquid beds nearest to the Equator; it would dilate
them, so as to raise them above their primitive level; by the single
effect of gravitation, they would glide on the surface towards the polar
zones. The absence of all solar radiation would tend, on the contrary,
to cool and contract them without this tendency. An exchange would be
established from the extremities towards the centre; in other words, a
counter current of cold and heavy water, calculated to replace the
losses occasioned by the action of solar radiation, would descend from
the Poles, but quite maintaining itself beneath the light and warm
current from the Equator."

In a like system of general circulation, the physical properties of pure
water, which attains its maximum of density seven degrees two seconds F.
below zero, would produce the most singular consequences. As its
temperature rose above that point, the water would become lighter,
having, consequently, a tendency to ascend towards the upper beds. After
this, the equatorial current, meeting in its progress towards the Poles
the cold water, would itself be cooled down; and when its temperature
had reached four degrees below zero, being now heavier than the polar
current, would change places with it, descending until it reached water
equally dense, while the polar current would ascend. Hence would arise a
sort of confusion of currents which would give to a fresh-water ocean
the strangest results, disarranging every instant the regular
circulation of its waters. It could not be so, however, in an ocean of
salt water, which attains its maximum specific gravity at four degrees
eight seconds F. below zero. By evaporation at the surface it is
concentrated and precipitated, and thus rendered denser than that
immediately below the surface. It consequently sinks, while the lower
beds come up to replace, in order to modify it, and in turn to be
precipitated in the same manner. "In this manner we find established a
continually ascending and descending movement, which carries down into
the depths of ocean the water warmed at the surface by the solar rays of
the Torrid zone. This double vertical current facilitates and prepares
the grand horizontal current which puts these submarine reservoirs of
heat in communication with the lower beds of the glacial sea. In the
Arctic basin the clouds, the melted snow, and the great rivers, which
have their mouths on the north of both continents, produce considerable
quantities of fresh water, which, mixing with the waves of the Polar
Sea, form a bed of mean density light enough to maintain itself and flow
off towards the Atlantic Ocean. These surface movements determine in the
lower regions certain contrary movements, whence originate the powerful
counter currents which ascend the Straits from Baffin's Bay and reappear
in the mysterious 'Polynia' of Kane, diffusing there its treasure of
heat brought from intertropical seas." Dr. Kane, in his interesting
Narrative, reports an open sea north of the parallel of eighty-two
degrees, which he and his party crossed a barrier of ice eighty miles
broad to reach, and before he reached it the thermometer marked sixty
degrees. Beyond this ice-bound region he found himself on the shores of
an iceless sea, extending in an unbroken sheet of water as far as the
eye could reach towards the Pole. Its waves were dashing on the beach
with the swell of a great ocean; the tides ebbed and flowed. Now the
question arises, Where did those tides have their origin? The tidal wave
of the Atlantic could not have passed under the icy barrier which De
Haven found so firm; therefore they must have been cradled in the cold
sea round the Pole; in which case it follows that most, if not all, the
unexplored regions about the Pole must be covered with deep water, the
only source of strong and regular tides. Seals were sporting and
waterfowl feeding in this open sea, as Dr. Kane tells us, and the
temperature of the water which rolled in and dashed at his feet with
measured beat was thirty-six degrees, while the bottom of the icy
barrier of eighty miles was probably hundreds of feet below the surface
level.

"The existence of these tides," says Maury, "with the immense flow and
drift which annually take place from the Polar Seas and the Atlantic,
suggests many conjectures as to the condition of these unexplored
regions. Whalemen have always been puzzled as to the breeding place of
the great whale. It is a cold-water animal, and, following up the train
of thought, the question arises, Is not the nursery for the great whale
in this Polar Sea, which is so set about and hemmed in by a hedge of
ice, that man may not trespass there?"

One or two points worthy of notice may be recorded here. Shallow water,
and water near the coast, or covering raised sand-banks, is colder than
water in the open sea. Alexander von Humboldt explains this phenomenon
by supposing that deep waters of higher temperature reascend from the
lowest depths and mingle with the upper beds. Fogs are frequently formed
over sand-banks, because the cold water which covers them produces a
local precipitation of atmospheric vapour. The contour of these fogs are
perfectly defined when seen from a distance: they reproduce the form and
accidents due to the submarine soil. Moreover, we often see clouds
arrested over these points, which look from afar like the peaks of
mountains.


FOOTNOTES:

[Footnote 1: "World before the Deluge." Second edition.]

[Footnote 2: Examen Comparatif des Principales eaux Minérales Salines de
France et d'Allemagne, par MM. L. Figuier et Mialhe. Read at the
Académie de Médecin, 23rd of May, 1848.]

[Footnote 3: Sir J. Herschel's "Physical Geography," p. 22, gives the
basis and details of this calculation.]

[Footnote 4: "La Terre et les Mers," p. 517. Troisième Ed.]



CHAPTER II.

CURRENTS OF THE OCEAN.

    "            ... seas that sweep
    The three-decker's oaken mast."

    TENNYSON.


The ocean is a scene of unceasing agitation; "its vast surface rises and
falls," to use the image suggested by Schleiden, "as if it were gifted
with a gentle power of respiration; its movements, gentle or powerful,
slow or rapid, are all determined by differences of temperature."

Heat increases its volume and changes the specific gravity of the water,
which is dilated or condensed in proportion to the change of
temperature. In proportion as it cools, water increases in density, and
descends into the depths until it reaches a constant temperature of four
degrees twenty-five minutes Cent. below zero, which it preserves in all
latitudes at the depth of a thousand yards, according to M. D'Urville.

If the water continues to cool, and reaches zero, it becomes lighter
than it was at four degrees twenty-five minutes Cent., and ascends in a
state of congelation--a process which, by an admirable provision of
nature, can only take place at the surface. So long as the temperature
is above four degrees twenty-five minutes, water is light, and ascends
to the surface, while colder water sinks to the bottom. Below four
degrees twenty-five minutes the process is reversed; the first
phenomenon is always in force under the Equator, the second near the
Poles. The evaporation, which is in continual operation in warm seas,
forming vast rain-clouds at the expense of the sea, is compensated by
unceasing currents of colder water flowing from the Poles. This
evaporation has a direct influence, moreover, on the density of sea
water, and is pointed out by Dr. Maury as a remarkable instance of the
compensations by which the oceanic waters are governed: "According to
Rodgers' observations," he says, "the average specific gravity of sea
water on the parallels of thirty-four degrees north and south, at a mean
temperature of sixty-four degrees, is just what it ought to be,
according to saline and thermal laws; but its specific gravity, when
taken from the Equator at a mean temperature of eighty-one degrees, is
much greater than, according to the same laws, it ought to be--the
observed difference being ·0015, whereas it ought to be ·0025. Let us
inquire," he adds, "what makes the equatorial waters so much heavier
than they ought to be.

"The anomaly occurs in the trade-wind region, and is best developed
between the parallel of forty degrees in the North Atlantic and the
Equator, where the water grows warmer, but not proportionally lighter.
The water sucked up by the trade-winds is fresh water, and the salt it
contained, being left behind, is just sufficient to counteract by its
weight the effect of thermal dilatation upon the specific gravity of
water between the parallels of thirty-four degrees north and south. The
thirsting of the trade-winds for vapour is so balanced as to produce
perfect compensation, and a more beautiful instance than we have here
stumbled upon is not, it appears to me, to be found in the mechanism of
the universe."

The oceanic currents are due to a great number of causes: the duration
and force of the winds, for instance; the rise and fall of tides all
over the globe; the variations in the density of the waters, according
to its temperature, and the evaporating powers of the atmosphere; the
depth and degree of saltness to which we have already alluded; finally,
to the variations of barometric pressure.

The currents which furrow the ocean present a striking contrast with the
immobility of the neighbouring waters; they form rivers of a determinate
breadth, whose banks are formed by the water in repose, and whose course
is often made quite perceptible by the vrachs and other aquatic plants
which follow in their train.

In order to comprehend the origin of these _pelagic rivers_, it is
necessary to consider the laws which govern the atmospheric currents, in
particular the _trade-winds_. "Hence," says Maury, "in studying the
system of oceanic circulation, we set out with the very simple
assumption, that from whatever part of the ocean a current is found to
run, to that same part a current of equal volume is bound to return;
for on this principle is based the whole system of currents and counter
currents." The differences of temperature between equinoctial and polar
countries generate two opposing currents, the upper one proceeding from
the Equator to the Poles, the lower one directed from the Poles towards
the Equator. On reaching the Equator, the cold current of air from the
Poles is warmed and rarefied, and ascends to the upper beds of the
atmosphere, whence it is again led to its point of departure; there it
is again cooled, and returns with the lower current towards the tropical
regions. But the rotatory movement of the earth modifies the direction
of these atmospheric currents. The movement by which it is carried from
west to east being almost nothing at the Poles, but inconceivably rapid
under the Equator, it follows that the cold air, in proportion as it
advances towards the Tropics, ought to incline a little towards the
west. This is just what takes place with these counter currents. The
_north-east trade-winds_, which prevail in the northern hemisphere, move
in a sort of spiral curve, turning to the west as they rush from the
Poles to the Equator, and in the opposite direction as they move from
the Equator towards the Poles; the immediate cause of this motion being
the rotation of the earth on its axis. "The earth," says Dr. Maury,
"moves from west to east. Now, if we imagine a particle of atmosphere at
the North Pole, where it is _at rest_, to be put in motion in a straight
line towards the Equator, we can easily see how this particle of air,
coming from the very axis of diurnal rotation, where it did not partake
of the diurnal motion, would, in consequence of its own _vis inertiæ_,
find as it travelled south that the earth was slipping from under it, as
it were, and it would appear to be coming from the north-east and going
towards the south-west; in other words, it would be a north-east wind."

In the same manner, the upper currents of air, which proceed towards the
Poles with equatorial rapidity, ought to outstrip the atmospheric beds,
which are gifted with much smaller rapidity of motion towards the Poles,
and turn them towards the east in consequence. These are the south-west
and north-west counter trade-winds, which, passing above the _north_ and
_south-east trades_, often sweep the surface of the sea in the latitudes
of the Temperate zone. The two _trades_ are separated by a belt more or
less broad, where the friction experienced at the surface of the sea
neutralizes their impulse towards the west; in general, the current of
air there is an ascending current. This belt, which does not exactly
correspond with the Equator, is called the _Zone of Calms_, where
atmospheric tempests frequently occur, and the winds make the entire
tour of the compass, which has acquired for them the name of
_tornadoes_.

The trade-winds, whose movement towards the west is retarded by the
friction which the waves of the ocean oppose to them, communicate to
these waves, by a sort of reaction, a tendency towards the west, or, to
speak more exactly, towards the south-west in the northern hemisphere,
and towards the north-west in the opposite hemisphere. The currents on
the surface of the water which result from this reaction, reunite under
the Equator, and form the _grand equinoctial_ current which impels the
waters of the east towards the west. This movement is stronger at the
edges than in the middle of the current, because the force which
produces it acts there with more energy: it results from this, that the
currents bifurcate more readily when any obstacle presents itself to its
movement. In the Atlantic Ocean, bifurcation takes place a little to the
south of the Equator; the southern branch descends along the coast of
Brazil, and probably returns by reascending along the west coast of
Africa. The northern branch follows the coast of Brazil and Guiana,
enters the Sea of the Antilles, and directs its course, reinforced by
the current which reaches it from the north-east, into the Bay of
Honduras, traverses the Yucatan Channel, and enters the Gulf of Mexico,
whence it debouches by the Florida Channel, under the name of the _Gulf
Stream_. Of this oceanic marvel Dr. Maury observes that "there is a
river in the bosom of the ocean; in the several droughts it never fails,
and in the mightiest floods it never overflows; its banks and its bottom
are of cold water, while its current is of warm; it takes its rise in
the Gulf of Mexico, and empties itself into the Arctic Seas. This mighty
river is the Gulf Stream. In no other part of the world is there such a
majestic flow of water; its current is more rapid than the Amazon, more
impetuous than the Mississippi, and its volume is more than a thousand
times greater. Its waters, as far as the Carolina coast, are of indigo
blue; they are so distinctly indicated that their line of junction can
be marked by the eye." Such is Dr. Maury's description of this powerful
current of warm water, which traverses the Atlantic Ocean, and
influences in no slight manner the climate of Northern Europe, and
especially our own shores.

The Gulf Stream thus described by the American _savant_ issues from the
Florida Channel, with a breadth of thirty-four miles, and a depth of two
thousand two hundred feet, moving at the rate of four and a half miles
per hour. The temperature of the water in the vicinity is about thirty
degrees Cent. From the American coast the current takes a north-east
direction towards Spitzbergen, its velocity and volume diminishing as it
expands in breadth. Towards the forty-third degree of latitude it forms
two branches, one of which strikes the coast of Ireland and of Norway,
whither it frequently transports seeds of tropical origin: it also warms
the frozen waters of the glacial sea. The other branch, inclining
towards the south, not far from the Azores, visits the coast of Africa,
whence it returns to the Antilles. Throughout this vast circuit may be
seen all sorts of plants and driftwood, with waifs and strays of every
description borne on the bosom of the ocean. "Midway the Atlantic, in
the triangular space between the Azores, Canaries, and Cape de Verd
Islands, is the great Sargasso Sea, covering an area equal in extent to
the Mississippi Valley: it is so thickly matted over with the Gulf Weed
(_Sargassum bacciferum_), that the speed of vessels passing through it
is actually retarded, and to the companions of Columbus it seemed to
mark the limits of navigation; they became alarmed. To the eye at a
little distance it seemed sufficiently substantial to walk upon." These
moving vegetable masses, always green, which tail off to a steady
breeze, serving as an anemometer to the mariner, afford an asylum to
multitudes of mollusks and crustaceans.

The Gulf Stream plays a grand part in the Atlantic system. It carries
the tepid water of the equinoctial regions into the high latitudes;
beyond the fortieth parallel the temperature is sixteen degrees Cent.
Urged by the south-west winds which predominate in that zone, its tepid
waters mix with those of the Northern Sea, softening the rigour of the
climate in these regions. To the south of the great bank of
Newfoundland, the warm current, in vast volume rushing from the Florida
Straits, meets the cold currents descending from the Arctic Circle
through Baffin's Bay and the Sea of Greenland, running with equal
velocity towards the south. A portion of these waters reascend towards
the Pole along the western coast of Greenland. It is to this conflict of
the polar and equatorial waters, that the formation of the banks of
Newfoundland is ascribed. Each of these great currents having
unceasingly deposited the débris carried in its bosom, the bank has been
thus formed bit by bit in the concourse of ages.

The difference of temperature between the Gulf Stream and the waters it
traverses gives birth inevitably to tempests and _cyclones_. In 1780 a
terrible storm ravaged the Antilles, in which twenty thousand persons
perished. The ocean quitted its bed and inundated whole cities; the
trunks of trees, mingled with other débris, were tossed into the air.
Numerous catastrophes of this kind have earned for the Gulf Stream the
title of the King of the Tempests. In consequence of the numerous
nautical documents which have been placed at the command of the National
Observatory of Washington, and the admirable use made of them by the
late Naval Secretary and his assistants, the directions and range of
these cyclones engendered by the Gulf Stream may be foreseen, and their
most dangerous ravages turned aside. As an example of the utility of Dr.
Maury's labours in settling the direction of storms in the traject of
the Gulf Stream, we quote a well-known instance: In the month of
December, 1859, the American packet _San Francisco_ was employed as a
transport to convey a regiment to California. It was overtaken by one of
these sudden storms, which placed the ship and its freight in a most
dangerous position. A single wave, which swept the deck, tore out the
masts, stopped the engines, and washed overboard a hundred and
twenty-nine persons, officers and soldiers. From that moment the
unfortunate steamer floated upon the waters, a waif abandoned to the
fury of the wind. The day after the disaster the _San Francisco_ was
seen in this desperate situation by a ship which reached New York,
although unable to assist her. Another ship met her some days after,
but, like the other, could render no assistance. When the report reached
New York, two steamers were despatched to her assistance; but in what
direction were they to go? what part of the ocean were they to explore?
The luminaries of Washington Observatory were appealed to! Having
consulted his charts as to the direction and limits of the Gulf Stream
at that period of the year, Dr. Maury traced on a chart the spot to
which the disabled steamer was likely to be driven by the current, and
the course to be taken by the vessels sent to her assistance. The crew
and passengers of the _San Francisco_ were saved before their arrival.
Three ships, which had seen their distressing situation, had been able
to reach them, and the steamers sent to their assistance only arrived
to witness the safety of the passengers and crew. But the point where
the steamer foundered shortly after they were transferred to the
rescuing ships was precisely that indicated by Dr. Maury. If the ships
sent to their assistance had reached in time, the triumph of SCIENCE
would have been complete.

The equinoctial currents of the Pacific are very imperfectly known. It
is believed, however, that they traverse the Great Ocean in its whole
length, and bifurcate opposite the Asiatic coast, where the weakest
branch bends northward until it encounters the polar current from
Behring's Straits, when it returns along the Mexican coast. The larger
branch inclines towards the south, passing round Australia, where it is
met by one or many counter currents coming from the Indian Ocean--of the
complicated and dangerous nature of which both Cook and La Peyrouse
speak.

The cold waters from the Antarctic Pole are carried towards the Equator
by three great oceanic rivers. The first bifurcates in forty-five
degrees; one portion goes round Cape Horn; the other--Humboldt's
current--ascends the Chilian and Peruvian coasts up to the Equator,
ameliorating the rainless climate as it goes, and making it delightful.
A second great current takes the direction of the African coast, and is
divided at the Cape, ascending both the east and west coasts of Africa.
On either side of the warm current which escapes from the intertropical
parts of the Indian Ocean, but especially along the Australian coast, a
polar current wends its way from the Antarctic regions, carrying
supplies of cold water to modify the climate and restore the equilibrium
in that part of the world. This cold current turns at first towards the
west, then towards the south in the direction of Madagascar; more to the
south still it is driven back by the polar current from Cape Horn. It is
thus that the warm waters from the Bay of Bengal, pressed by the Indian
polar current, circulate between Africa and Australia, one lateral
branch of the current sweeping along the south coast of this vast
continent.

       *       *       *       *       *

The monsoons which reign in the Indian Ocean tend still more to
complicate the currents, already sufficiently intricate and confused.
But it is not intended at present to occupy the reader's attention
further with these questions of intricate currents.

We have already spoken of a submarine current which appears to carry
the waters of the Mediterranean into the Atlantic Ocean. Its existence
is in some respects established by calculations which prove that the
quantity of salt water supplied by the upper current through the Straits
of Gibraltar is equal to seventy-two cubic miles per annum, while the
quantity of fresh water brought down by the rivers is equal to six, and
the quantity lost by evaporation to twelve cubic miles per annum. This
would leave an annual excess of sixty-six cubic miles, if the
equilibrium was not re-established by an under current flowing into the
Atlantic. This hypothesis would appear to have been confirmed by a very
curious fact.

Towards the end of the seventeenth century, a Dutch brig, pursued by the
French corsair _Phoenix_, was overhauled between Tangier and Tarifa, and
seemed to be sunk by a single broadside; but, in place of foundering and
going down, the brig, being freighted with a cargo of oil and alcohol,
floated between the two currents, and, drifting towards the west,
finally ran aground, after two or three days, in the neighbourhood of
Tangier, more than twelve miles from the spot where she had disappeared
under the waves. She had therefore traversed that distance, drawn by the
action of the under current in a direction opposite to that of the
surface current. This ascertained fact, added to some recent
experiments, lend their support to the opinion which admits of the
existence of an outward current through the Straits of Gibraltar. Dr.
Maury quotes an extract from the "log" of Lieutenant Temple, of the
United States Navy, bearing the same inference. At noon on the 8th of
March, 1855, the ship _Levant_ stood into Almeria Bay, where many ships
were waiting for a chance to get westwards. Here he was told that at
least a thousand sail were waiting between the bay and Gibraltar, "some
of them having got as far as Malaga only to be swept back again.
Indeed," he adds, "no vessel had been able to get out into the Atlantic
for three months past." Supposing this current to run no faster than two
knots an hour, and assuming its depth to be four hundred feet only, and
its width seven miles, and that it contained the average proportion of
solid matter, estimated at one-thirtieth, it appears that salt enough to
make eighty-eight cubic miles of solid matter were carried into the
Mediterranean in those ninety days. "Now," continues Dr. Maury, "unless
there were some escape for all this solid matter which has been running
into the sea, not for ninety days, but for ages, it is very clear that
the Mediterranean would long ere this have been a vat of strong brine,
or a bed of cubic crystals."

For the same reason, Dr. Maury considers it certain that there is an
under current to the south of Cape Horn, which carries into the Pacific
Ocean the overflowings of the Atlantic. In fact, the Atlantic is fed
unceasingly by the Great American rivers, while the Pacific receives no
important affluent, but ought to be, and is, subjected to enormous
losses, in consequence of the evaporation continually taking place at
the surface.


TIDES.

Tides are periodical movements produced by the attraction of the sun and
moon. This action, which influences the whole mass of the earth, is made
manifest by the swelling movement of the waters. The attractive force
exercised by the moon is three times that of the sun, in consequence of
its approximation to the earth, as compared to the greater luminary.

In order to comprehend the theory of tides, we shall first consider the
_lunar_ influences, putting aside for a moment the _solar_ action.

[Illustration: Fig. 5. Lunar Tides.]

The attraction which the moon exercises upon any point on the earth's
surface is in the inverse ratio of the square of its distance. If we
draw a straight line from the moon passing through the centre of the
earth, this line will meet the surface of the waters at two points
diametrically opposite to each other--namely, Z and N (Fig. 5); one of
these points would be to the moon its _zenith_, the other its _nadir_.
The point of the sea which has the moon in the zenith--namely, that
above which the moon is perfectly perpendicular--will be nearest to the
planet, and will consequently be more strongly attractive to the centre
of the earth, while the points diametrically opposite to which the moon
is the _nadir_ will be more distant, and consequently less strongly
attracted by that luminary. It follows that the waters situated directly
under the moon will be attracted towards it, and form an accumulation or
swelling at that point; the waters at the antipodes being less strongly
attracted to the moon than to the centre of the earth, will form also a
secondary swelling on the surface of the sea, thus forming a double
tide, accumulating at the point nearest the moon and at its antipodes.
At the intermediate points of the circumference of the globe, where the
waters are not subjected to the direct attraction of the moon, the sea
is at low water, as represented in Fig. 5.

The earth, in its movement of rotation, presents, in the course of
twenty-four hours, every meridian on its surface to the lunar
attraction; consequently, each point in its turn, and at intervals of
six hours, is either under the moon, or ninety degrees removed from it:
it follows, that in the space of a lunar day--that is to say, in the
time which passes between two successive passages of the moon on the
same meridian--the oceanic waters will be at high and low tide twice in
the month on every point of the surface of the globe. But this result of
attraction is not exercised instantaneously. The moon has passed from
the meridian of the spot before the waters have attained their greatest
height; the flux reaches its maximum about three hours after the moon
has culminated; and the watery mountain follows the moon all round the
globe, from east to west, about three hours in its rear.

It is obvious, however, that the great inequalities of the bottom of the
sea; the existence of continents; the slopes of the coast, more or less
steep; the different breadths of channels and straits; finally, the
winds, the pelagic currents, and a crowd of local circumstances,--must
materially modify the course of the tides. Nor is the moon the only
celestial body which influences the rise and fall of the waters of the
sea. We have already said that the sun asserts an influence on the
waves. It is true that, in consequence of its great distance, this only
amounts to a thirty-eight-hundredth part of that of the earth's
satellite. The inequality which exists between the solar and lunar
days--the latter exceeding the first by fifty-four minutes--has also the
effect of adding to or subtracting from this force alternately. When the
sun and moon are in _conjunction_ (Fig. 6), or in opposition, that is to
say, placed upon the same right line, their attraction on the sea is
combined, and a _spring_ tide is produced. This happens at the period of
the _syzygies_--the period of new and full moon. At the period of the
_quadrature_, or the first and last quarters, the solar action, being
opposed to that of lunar attraction, tends to produce a sensibly weaker
tide.

[Illustration: Fig. 6. Lunar-Solar Tides.]

These effects are never produced instantaneously; but, the impulse once
given, it will continue to influence the tides for two or three days,
the highest and lowest tides being nearly in the proportion of 138 to
63, or of 7 to 3. The highest tides occur at the _equinoxes_, when the
moon is in perigee; the lowest at the _solstices_, when it is in apogee.
In our ports, and along the coast, the water rises twice in twenty-four
hours, when it is said to be high water; when it retires, it is low
water: they are respectively the _flux_ and _reflux_ of the waves.

The tide is retarded every day about fifty minutes, the lunar day being
twenty-four hours fifty minutes of mean time. If, for instance, it is
high water to-day at two o'clock in the morning, that of the next day
will take place at fifty minutes past two. Low water does not occur,
however, at the half of the intermediate time; the flux is more rapid
than the reflux: thus at Havre, Boulogne, and at corresponding places on
this side of the Channel, it takes two hours and eight minutes more in
retiring; at Brest, the difference is only sixteen minutes more than the
flux. The daily retardation of high water by the passage of the moon in
the meridian, at the equinoxes, is a constant quantity for the same
locality, which can be determined by direct observation.

The height of the tide varies in the different regions of the globe,
according to local circumstances. The eastern coast of Asia and the
western coast of Europe are exposed to extremely high tides; while in
the South Sea Islands, where they are very regular, they scarcely reach
the height of twenty inches. On the western coast of South America, the
tides rarely reach three yards; on the western coast of India they reach
the height of six or seven; and in the Gulf of Cambay it ranges from
five to six fathoms. This great difference makes itself felt in our own
and adjoining countries: thus, the tide, which at Cherbourg is seven and
eight yards high, attains the height of fourteen yards at Saint Malo,
while it reaches the height of ten yards at Swansea, at the mouth of the
Bristol Channel, increasing to double that height at Chepstow, higher up
the river. In general, the tide is higher at the bottom of a gulf than
at its mouth.

       *       *       *       *       *

The highest tide which is known occurs in the Bay of Fundy, which opens
up to the south of the isthmus uniting Nova Scotia and New Brunswick.
There the tide reaches forty, fifty, and even sixty feet, while it only
attains the height of seven or eight in the bay to the north of the same
isthmus. It is related that a ship was cast ashore upon a rock during
the night, so high, that at daybreak the crew found themselves and their
ship suspended in mid-air far above the water!

In the Mediterranean, which only communicates with the ocean by a narrow
channel, the phenomenon of tides is scarcely felt, and from this
cause--that the moon acts at the same time upon its whole surface, which
are not sufficiently abundant to increase the swelling mass of waters
formed by the moon's attraction; consequently, the swelling remains
scarcely perceptible. This is the reason why neither the Black Sea or
White Sea presents a tide, and the Mediterranean a very inconsiderable
one. Nevertheless, at Alexandria the tide rises twenty inches, and at
Venice this height is increased to about six feet and a half. Lake
Michigan is slightly affected by the lunar attraction.

       *       *       *       *       *

Professor Whewell has prepared maps, in which the course of the tidal
wave is traced in every country of the globe. We see here that it
traverses the Atlantic, from the fiftieth degree of south latitude up to
the fiftieth parallel north, at the rate of five hundred and sixty miles
an hour. But the rapidity with which it proceeds is least in shallow
water. In the North Sea it travels at the rate of a hundred and eighty
miles. The tidal wave which proceeds round the coast of Scotland
traverses the German Ocean and meets in St. George's Channel, between
England and Ireland, where the conflict between the two opposing waves
presents some very complicated phenomena.

The winds, again, exercise a great influence on the height of the tides.
When the impulse of the wind is added to that of the attracting planet,
the normal height of the wave is considerably increased. If the wind is
contrary, the flux of the tide is almost annihilated. This happens in
the Gulf of Vera Cruz, where the tide is only perceptible once in three
days, when the wind blows with violence. An analogous phenomenon is
observable on the coast of Tasmania.

[Illustration: Fig. 7. Point du Raz, Coast of Brittany.]

The rising tide sometimes strikes the shore with a continuous and
incredible force. This violent shock is called the _surf_. The swell
then forms a billow, which expands to half a mile. The surf increases as
it approaches the coast, when it sometimes attains the height of six or
seven yards, forming an overhanging mountain of water, which gradually
sinks as it rolls over itself. But this motion is not in reality
progressive--it transports no floating body. The surf is very strong at
the Isle of Fogo, one of the Cape de Verd Islands in the Indian Ocean,
and at Sumatra, where the surf renders it dangerous and sometimes
impossible to land on the coast. Fig. 7 represents the effects of the
surf at Point du Raz, on the coast of Brittany. The winds adding their
influence to these causes, give birth on the surface of the sea to waves
or billows, which increase rapidly, rising in foaming mountains,
rolling, bounding, and breaking one against the other. "In one moment,"
says Malte Brun, "the waves seem to carry sea-goddesses on its breast,
which seem to revel amid plays and dances; in the next instant, a
tempest rising out of them, seems to be animated by its fury. They seem
to swell with passion, and we think we see in them marine monsters which
are prepared for war. A strong, constant, and equal wind produces long
swelling billows, which, rising on the same line, advance with a uniform
movement, one after the other, precipitating themselves upon the coast.
Sometimes these billows are suspended by the wind or arrested by some
current, thus forming, as it were, a liquid wall. In this position,
unhappy is the daring navigator who is subjected to its fury." The
highest waves are those which prevail in the offing off the Cape of Good
Hope at the period of high tide, under the influence of a strong
north-west wind, which has traversed the South Atlantic, pressing its
waters towards the Cape. "The billows there lift themselves up in long
ridges," says Dr. Maury, "with deep hollows between them. They run high
and fast, tossing their white caps aloft in the air, looking like the
green hills of a rolling prairie capped with snow, and chasing each
other in sport. Still, their march is stately, and their roll majestic.
The scenery among them is grand. Many an Australian-bound trader, after
doubling the Cape, finds herself followed for weeks at a time by these
magnificent rolling swells, furiously driven and lashed by the "brave
west winds." These billows are said to attain the height of thirty, and
even forty feet; but no very exact measurement of the height of waves is
recorded. One of these mountain waves placed between two ships conceals
each of them from the other--an effect which is partially represented in
Fig. 8. In rounding Cape Horn, waves are encountered from twenty to
thirty feet high; but in the Channel they rarely exceed the height of
nine or ten feet, except when they come in contact with some powerful
resisting obstacle. Thus, when billows are dashed violently against the
Eddystone Lighthouse, the spray goes right over the building, which
stands a hundred and thirty feet above the sea, and falls in torrents on
the roof. After the storm of Barbadoes in 1780, some old guns were
found on the shore, which had been thrown up from the bottom of the sea
by the force of the tempests.

[Illustration: Fig. 8. Height of Waves off the Cape of Good Hope.]

If the waves, in their reflux, meet with obstacles, whirlpools and
whirlwinds are the result--the former the terror of navigators. Such are
the whirlpools known in the Straits of Messina, between the rocks of
Charybdis and Scylla, celebrated as the terror of ancient mariners, and
which were sung by Homer, Ovid, and Virgil:--

    "Scylla latus dextrum, lævum irrequieta Charybdis,
    Infestat; vorat hæc raptis revomitque carinas.
    ... Incidit in Scyllam, cupiens vitare Charybdim."

These rocks are better understood, and less redoubted in our days. At
Charybdis, there is a foaming whirlpool; at Scylla, the waves dash
against the low wall of rock which forms the promontory, scarcely
noticed by the navigator of our days.

Another celebrated whirlpool is that of Euripus, near the Island of
Euboea; another is known in the Gulf of Bothnia. But perhaps the best
known rocky danger is the Maelström, whose waters have a gyratory
movement, producing a whirlpool at certain states of the tide, the
result of opposing currents, which change every six hours, and which,
from its power and magnitude, is capable of attracting and engulfing
ships to their destruction, although chiefly dangerous to smaller craft.

To the combined effects of tides and whirlpools may also be attributed
the hurricanes, so dreaded by navigators, which so frequently visit the
Mauritius and other parts of the Indian Ocean. In periods of the utmost
calms, when there is scarcely a breath to ruffle the air, these shores
are sometimes visited by immense waves, accompanied by whirlwinds, which
seem capable of blowing the ships out of the water, seizing them by the
keel, whirling them round on an axis, and finally capsizing them. "At
the period of the changing monsoon, the winds, breaking loose from their
controlling forces, seem to rage with a fury capable of breaking up the
very fountains of the deep."

The hurricanes of the Atlantic occur in the months of August and
September, while the south-west monsoon of Africa and the southeast
monsoon of the West Indies are at their height; the agents of the one
drawing the north-east trade-winds into the interior of Mexico and
Texas, the other drawing them into the interior of Africa, greatly
disturbing the equilibrium of the atmosphere.


THE POLAR SEAS.

The extreme columns of the known world are Mount Parry, situated at
eight degrees from the North Pole, and Mount Ross, twelve degrees from
the South Pole. Beyond these limits our maps are mute; a blank space
marks each extremity of the terrestrial axis. Will man ever succeed in
passing these icy barriers? Will he ever justify the prediction of the
poet Seneca, who tells us that "the time will come in the distant future
when Ocean will relax her hold on the world, when the immense earth will
be open, when Tethys will appear amid new orbs, and where Thule
(Iceland) shall no longer be the extreme limit of the earth?"

          "Venient annis
    Sæcula seris quibus oceanus
    Vincula rerum laxet et ingens
    Pateat tellus, Tethysque novos
    Detegat orbes, nec sit terris
    Ultime Thule."

    _Medea._

No one can say. Every step we have taken in order to approach the Pole
has been dearly purchased; and it is not without reason that navigators
have named the south point of Greenland, Cape Farewell. Of the number of
expeditions, for the most part English, which have been fitted out, at
the cost of nearly a million sterling, to explore the Frozen Ocean,
one-twentieth have had for their mission to ascertain the fate of the
lamented Sir John Franklin.

The first navigator who penetrated to Arctic polar regions was Sebastian
Cabot, who in 1498 sought a north-west passage from Europe to China and
the Indies. Considering the date, and the state of navigation at that
period, this was perhaps the boldest attempt on record. Scandinavian
traditions attribute similar undertakings to the son of the King Rodian,
who lived in the seventh century; to Osher, the Norwegian, in 873; and
to the Princes Harold and Magnus, in 1150.

Sebastian Cabot reached as high as Hudson's Bay, but a mutiny of his
sailors forced him to retrace his steps. In 1500, Gaspard de Cortereal
discovered Labrador; in 1553, Sir Hugh Willoughby Nova Zembla; and
Chancellor the White Sea, about the same time. Davis visited in 1585 the
west coast of Greenland, and two years later he discovered the strait
which bears his name. In 1596 Barentz discovered Spitzbergen, which was
again seen by Hendrich Hudson, who sailed up to and beyond the
eighty-second parallel. Three years later Hudson gave his name to the
great Labrador Bay, but he could get no farther. His crew also revolted,
and he was left in the ship's launch with his son, seven sailors, and
the carpenter, who remained faithful. Thus perished one of our greatest
navigators.

The Island of Jan Mayen was discovered in 1611; the channel which Baffin
took for a bay, and which bears his name, was discovered in 1616.
Behring discovered, in his first voyage in 1727, the strait which
separates Siberia from America; he sailed through it in 1741, but his
ship was stranded, and he himself died of scorbutic disease.

In the year 1771 the Polar Sea was discovered by Hearne, a fur merchant;
it was explored long after by Mackenzie.

From the year 1810, when Sir John Ross, Franklin, and Parry turned their
attention to the Arctic regions, these expeditions to the Polar Seas
rapidly succeeded each other. In 1827 Parry reached the eighty-second
degree of north latitude; and in 1845 Sir John Franklin, with the ships
_Erebus_ and _Terror_, and their crews, departed on their last voyage,
from which neither he nor his companions ever returned. There is now no
doubt that they perished miserably, after having discovered the
north-west passage, which Captain M'Clure also discovered, coming from
the opposite direction, in 1850. In 1855 the expedition of Dr. Elisha
Kane found the sea open from the Pole.

       *       *       *       *       *

The Antarctic Pole had in the meantime attracted the attention of
navigators. In 1772 the Dutch captain, Kerguelen, discovered an island
which he took for a continent. In 1774 Captain Cook explored these
regions up to the seventy-first degree of latitude. James Weddell, in a
small whaler, sailed past this parallel in 1823. Biscoe discovered
Enderby's Land in 1831. The _Zelée_ and _Astrolabe_, under the command
of Captain Dumont D'Urville, of the French Marine, and the American
expedition, under Captain Wilkes, reached the same region in 1838. The
former discovered Adelia's Land. Finally, in 1841, Sir James Clark Ross,
nephew of Sir John Ross, with the _Erebus_ and _Terror_, penetrated up
to the seventy-eighth degree south latitude. Here he discovered the
volcanic islands which he named after his ships, and, farther to the
south, a new continent or land, which he called Victoria's Land.

While these efforts were being made to penetrate the ice which surrounds
the Antarctic Pole, a region having little which could attract human
enterprise, the interests of commerce seemed to call for obstinate and
persevering attempts to penetrate to the Arctic Pole. In spite of these
numerous expeditions, however, which extend over two centuries, the
regions round the North Pole are far from being known to geographers.
The fogs and snows which almost always cover them were the source of
many errors made by the earlier navigators. In his first voyage, made in
1818, Sir John Ross was led to think that Lancaster Sound was closed by
a chain of mountains, which he called the Croker Mountains; but in the
following year Captain Parry, in command of two ships, the _Hecla_ and
_Griper_, discovered that this was an error. This celebrated navigator
discovered Barrow's Straits, Wellington Channel, and Prince Regent
Inlet; Cornwallis, Sir Byam Martin, and Melville Islands, to which the
name of Parry's Archipelago has been given. In this short voyage he
gathered more new results than were obtained by his successors during
the next forty years. He was the first to traverse these seas. Upon Sir
Byam Martin Island he has described the ruins of some ancient
habitations of the Esquimaux. He passed the winter on Melville Island.
In order to attain his chosen anchorage in Winter's Bay, he was
compelled to saw a passage in the ice of a league in length, which
involved the labour of three days; but scarcely were they moored in
their chosen harbour than the thermometer fell to eighteen degrees below
zero. They carried ashore the ship's boats, the cables, the sails, and
log-books. The masts were struck to the maintop; the rest of the rigging
served to form a roof, sloping to the gunwale, with a thick covering of
sail-cloth, which formed an admirable shelter from the wind and snow.
Numberless precautions were taken against cold and wet under the decks.
Stoves and other contrivances maintained a supportable degree of
temperature. In each dormitory a false ceiling of impermeable cloth
interposed to prevent the collection of moisture on the wooden walls of
the ship. The crew were divided into companies, each company being under
the charge of an officer, charged with the daily inspection of their
clothes and cleanliness--an essential protection against scurvy. As a
measure of precaution, Captain Parry reduced by one-third the ordinary
ration of bread; beer and wine were substituted for spirits; and citron
and lemon drinks were served out daily to the sailors. Game was
sometimes substituted to vary a repast worthy of Spartans. As a remedy
against _ennui_, a theatre was fitted up and comedies acted, for which
occasions Parry himself composed a vaudeville, entitled "The North-west
Passage; or, the End of the Voyage." During this long night of
eighty-four days, the thermometer in the saloons marked 28°, and outside
35° below zero, and for a few minutes actually reached 47°. Some of the
sailors had their members frozen, from which they never quite recovered.
One day the hut which served as an observatory was discovered to be on
fire. A sailor who saved one of the precious instruments lost his hands
in the effort; they were completely frost-bitten in the attempt.

Nevertheless, the month of June arrived, and with it the opportunity of
making excursions in the neighbourhood. It was found that, in Melville
Island, the earth was carpeted with moss and herbage, with saxifrages
and poppies. Hares, reindeer, the musk-ox, northern geese, plovers,
white wolves and foxes, roamed around their haunts, disputing their
booty with the crew. Captain Parry could not risk a second winter in
this terrible region. He returned home as soon as the thaw left the
passage open.

In 1821, Captain Parry undertook a second voyage with the _Fury_ and
_Hecla_. He visited Hudson's Bay and Fox's Channel. In his third voyage,
undertaken in 1824, he was surprised by the frost in Prince Regent's
Channel, and was constrained to pass the winter there. The _Fury_ was
dismantled, and, being found unfit for service, Captain Parry was
obliged to abandon her and return to England.

Accompanied by Sir James Ross, Parry again put to sea in the _Hecla_, in
April, 1826. On his third voyage, on leaving Table Island on the north
of Spitzbergen, Parry placed his crew in the two training ships,
_Enterprise_ and _Endeavour_; the first under his own command, the
second under orders of Sir James Ross. Sometimes they sailed, sometimes
hauled through the crust of the ice; sometimes the ice, which pierced
their shoes, showed itself bristling with points, intersected into
valleys and little hills, which it was difficult to scale. In spite of
the courage and energy of their crews, the two ships scarcely advanced
four miles a day, while the drifting of the ice towards the south led
them imperceptibly towards their point of departure. They reached
latitude eighty-two degrees forty-five minutes fifteen seconds, however,
and this was the extreme point which they attained.

In the month of May, 1829, Sir John Ross, accompanied by his nephew,
James Clark Ross, again turned towards the Polar Seas. He entered Prince
Regent's Channel, and there he found the _Fury_, which had been
dismantled and abandoned by Parry, in these regions, eight years before.
The provisions, which the old ship still contained, were quite a
providential resource to Ross's crews. The distinguished navigator
explored the Boothian Peninsula, and passed four years consecutively in
Port Felix, without being able to disengage his vessel, the _Victory_.
This gave him ample leisure to become familiar with the Esquimaux. Sir
John Ross, in his account of this long sojourn in polar countries, has
recorded many conversations with the natives, which our space does not
permit us to quote. From this terrible position he was extricated, and
emerged with his crew from this icy prison, when all hope of his return
had been abandoned. After being exposed to a thousand dangers, Ross and
his crew were at last observed by a whaling ship, which received them on
board, after many efforts to attract attention. On learning that the
ship which had saved them was the _Isabella_, formerly commanded by
Captain Ross, he made himself known. "But Captain Ross has been dead two
years," was the reply.

We need not repeat here the enthusiastic reception Captain Ross and his
companions met with on their arrival in London.

During an excursion made by the nephew of the Commander (afterwards Sir
James Clark Ross), he very closely approached the North Magnetic Pole.
This was at eight o'clock on the morning of the 1st of June, 1831, on
the west coast of Boothia. The dip of the magnetic needle was nearly
vertical, being eighty-nine degrees fifty-nine seconds--one minute short
of ninety degrees. The site was a low flat shore, rising into ridges
from fifty to sixty feet high, and about a mile inland.

       *       *       *       *       *

Contrary to the judgment of many officers of experience in polar
explorations, the last and most fatal of all the expeditions was
undertaken by Sir John Franklin, with one hundred and thirty-seven
picked officers and men, in the ships _Erebus_ and _Terror_. The
adventurers left Sheerness on the 26th of May, 1846, the ships having
been strengthened in every conceivable way, and found in everything
calculated to secure the safety of the expedition. On the 22nd of July
the ships were spoken by the whaler _Enterprise_, and, four days later,
they were sighted by the _Prince of Wales_, of Hull, moored to an
iceberg, waiting an opening to enter Lancaster Sound. There the veil
dropped over the ships and their unhappy crews. In 1848, their fate
began to excite a lively interest in the public mind. Expedition in
search of them succeeded expedition, at immense cost, sent both by the
English and American authorities, and by Lady Franklin herself, some of
which penetrated the Polar Seas through Behring's Straits, while the
majority took Baffin's Bay. In 1850, Captains Ommaney and Penny
discovered, at the entrance of Wellington Channel, some vestiges of
Franklin, which led to another expedition in 1857, which was got up by
private enterprise, of which Captain M'Clintock had the command. Guided
by the indications collected in the previous expedition, and
intelligence gathered from the Esquimaux by Dr. Rae in his land
expedition, Captain M'Clintock in the yacht _Fox_ discovered, on the 6th
of May, 1859, upon the north point of King William's Land, a cairn or
heap of stones. Several leaves of parchment, which were buried under the
stones, bearing date the 28th of April, 1848, solved the fatal enigma.
The first, dated the 24th of May, 1847, gave some details ending with
"all well." The papers had been dug up twelve months later to record the
death of Franklin, on the 11th of June, 1847. The survivors are supposed
to have been on their way to the mouth of the River Back, but they must
have sunk under the terrible hardships to which they were exposed, in
addition to cold and hunger.

In September, 1859, Captain M'Clintock returned to England, bringing
with him many relics of our lost countrymen, found in the theatre of
their misfortunes.

It only remains to us to say a few words on the latest voyages
undertaken in the Polar Seas. After the return of Captain M'Clintock, in
1850, Captain M'Clure, leaving Behring's Straits, discovered the
north-west passage between Melville and Baring's Island, which passage
had been sought for without success during so many ages. He saw the
thermometer descend fifty degrees below zero. In the month of October,
1854, he returned to England, and at a subsequent period it was
ascertained with certainty that, before his death, Franklin knew of the
other passage which exists to the north of America, to the south of
Victoria Land, and Wollaston.

The expedition of Dr. Kane entered Smith's Strait in 1853, and advanced
towards the north upon sledges drawn by dogs; the mean temperature,
which ranged between thirty degrees and forty degrees below zero, fell
at last to fifty degrees. At eleven degrees from the Pole they found two
Esquimaux villages, called Etah and Peterovik, then an immense glacier.
A detachment, conducted by Lieutenant Morton, discovered, beyond the
eightieth degree of latitude, an open channel inhabited by innumerable
swarms of birds, consisting of swallows, ducks, and gulls, which
delighted them by their shrill, piercing cries. Seals (_phoca_) enjoyed
themselves on the floating ice. In ascending the banks, they met with
flowering plants, such as _Lychnis_, _Hesperis_, &c. On the 24th of
June, Morton hoisted the flag of the _Antarctic_, which had before this
seen the ice of the South Pole, on Cape Independence, situated beyond
eighty-one degrees. To the north stretched the open sea. On the left was
the western bank of the Kennedy Channel, which seemed to terminate in a
chain of mountains, the principal peak rising from nine thousand to ten
thousand feet, which was named Mount Parry. The expedition returned
towards the south, and reached the port of Uppernavick exhausted with
hunger, where it was received on board an American ship. Dr. Kane,
weakened by his sufferings, from which he never quite recovered, died in
1857.

We cannot conclude this rapid sketch of events connected with the
expeditions to the Arctic Pole without noting a geological fact of great
and singular interest. When opportunities have presented themselves of
examining the rocks in the regions adjoining the North Pole, it has been
found that great numbers belong to the coal measures. Such is the case
in Melville Island and Prince Patrick's Island. Under the ice which
covers the soil in these islands coal exists, with all the fossil
vegetable débris which invariably accompany it. This shows that in the
coal period of geology, the North Pole was covered with the rich and
abundant vegetation whose remains constitute the coal-fields of the
present day; and proves to demonstration that the temperature of these
regions was, at one period of the earth's history, equal to that of
equatorial countries of the present day. What a wonderful change in the
temperature of these regions is thus indicated! It is, indeed, a strange
contrast to find coal formations under the soil covered by the polar
ice. Let us suppose that human industry should dream of establishing
itself in these countries, and drawing from the earth the combustible so
needed to make it habitable, thus furnishing the means of overcoming the
rigorous climatic conditions of these inhospitable regions.

       *       *       *       *       *

The Antarctic Pole is probably surrounded by an icy canopy not less than
two thousand five hundred miles in diameter; and numerous circumstances
lead to the conclusion that the vast mass has diminished since 1774,
when the region was visited by Captain Cook. The Antarctic region can
only be approached during the summer, namely, in December, January, and
February.

The first navigator who penetrated the Antarctic circle was the Dutch
captain, Theodoric de Gheritk, whose vessel formed part of the squadron
commanded by Simon de Cordes, destined for the East Indies. In January,
1600, a tempest having dispersed the squadron, Captain Gheritk was
driven as far south as the sixty-fourth parallel, where he observed a
coast which reminded him of Norway. It was mountainous, covered with
snow, stretching from the coast to the Isles of Solomon. The report of
Simon de Cordes was received with great incredulity, and the doubts
raised were only dissipated when the New South Shetland Islands were
definitely recognized. The idea of an Antarctic continent is, however,
one of the oldest conceptions of speculative geography, and one which
mariners and philosophers alike have found it most difficult to
relinquish. The existence of a southern continent seemed to them to be
the necessary counterpoise to the Arctic land. The _Terra Australis
incognita_ is marked on all the maps of Mercator, round the South Pole,
and when the Dutch officer, Kerguelen, discovered, in 1772, the island
which bears his name, he quoted this idea of Mercator as the motive
which suggested the voyage. In 1774, Captain Cook ventured up to and
beyond the seventy-first degree of latitude under the one hundred and
ninth degree west longitude. He traversed a hundred and eighty leagues,
between the fiftieth degree and sixtieth degree of south latitude,
without finding the land of which mariners had spoken: this led him to
conclude that mountains of ice, or the great fog-banks of the region,
had been mistaken for a continent. Nevertheless, Cook clung to the idea
of the existence of a southern continent. "I firmly believe," he says,
"that near the Pole there is land where most part of the ice is formed
which is spread over the vast Southern Ocean. I cannot believe that the
ice could extend itself so far if it had not land--and I venture to say
land of considerable extent--to the south. I believe, nevertheless, that
the greater part of this southern continent ought to lie within the
Polar Circle, where the sea is so encumbered with ice as to be
unapproachable. The danger run in surveying a coast in these unknown
seas is so great, that I dare to say no one will venture to go farther
than I have, and that the land that lies to the south will always remain
unknown. The fogs are there too dense; the snowstorms and tempests too
frequent; the cold too severe; all the dangers of navigation too
numerous. The appearance of the coast is the most horrible that can be
imagined. The country is condemned by nature to remain unvisited by the
sun, and buried under eternal hoar frost. After this report, I believe
that we shall hear no more of a southern continent." This description of
these desolate regions, to which the great navigator might have applied
the words of Pliny, "_Pars mundi a natura damnata et densa mersa
caligine_," only excited the courage of his successors. In our days,
several expeditions have been fitted out for the express survey of
regions which may be characterised as the abode of cold, silence, and
death. In 1833, a free passage opened itself into the Antarctic Sea. The
Scottish whaling ship, commanded by James Weddell, entered the pack ice,
and penetrated it in pursuit of seals; but having, by chance, found the
sea open on his course, he forced his way up to seventy-four degrees
south latitude, and under the thirty-fourth degree of longitude, but the
season was too advanced, and he and his crew retraced their steps. The
voyage of Captain Weddell caused a great sensation, and suggested the
possibility of more serious expeditions. Twelve years later three great
expeditions were fitted out: one, under Dumont D'Urville, of the French
Marine; an American expedition, under Captain Wilkes, of the United
States Navy; and an English expedition, under Sir James Clark Ross.

Dumont D'Urville, who perished so miserably in the railway catastrophe
at Versailles, in 1842, passed the Straits of Magellan on the 9th of
January, 1838, having under his command the two corvettes _Astrolabe_
and _Zelée_. He expected to find it as Weddell had described, and that,
after passing the first icy barrier, he should find an open sea before
him. But he was soon compelled to renounce this hope. The floating
icebergs became more and more closely packed and dangerous. The southern
icebergs do not circulate in straits and channels already formed, like
those of the North Pole, but in enormous detached blocks which hug the
land. Sometimes in shallow water they form belts parallel to the base of
the cliffs, intersected by a small number of sinuous narrow channels.
These icy cliffs present a face more or less disintegrated as they
approximate to the rocky shore. The blocks of ice form at first huge
prisms, or tabular, regular masses of a whitish paste; but they get used
up by degrees, and rounded off and separated under the action of the
waves, which chafe them, and their colour becomes more and more limpid
and bluish. They ascend freely towards the north, in spite of the winds
and currents which carry them in the contrary direction. One year with
another these floating icebergs accumulate with very striking
differences, and it is only by a rare chance that they open up a free
passage such as Captain Weddell had discovered. These floating islands
of ice have been met with in thirty-five degrees south latitude, and
even as high as Cape Horn.

The two French ships frequently found themselves shut up in the
icebergs, which continued to press upon them, and driven before the
north winds, until the south wind again dispersed their vast masses,
enabling them to issue from their prison in health and safety. In some
cases D'Urville found it necessary to force his ship through fields of
ice by which he was surrounded and imprisoned, and to cut his way by
force through the accumulating blocks, using the corvette as a sort of
battering-ram. In 1838 he recognized, about fifty leagues from the South
Orkney Isles, a coast, to which he gave the name of _Louis Philippe's_
and _Joinville's Land_. This coast is covered with enormous masses of
ice, which seemed to rise to the height of two thousand six hundred
feet. Ross discovered still more lofty peaks, such as Mount Penny and
Mount Haddington, rising about seven thousand feet. The English
navigator states that this land is only a great island. The crew of
D'Urville's ship being sickly and overworked, he returned to the port of
Chili, whence he again issued for the South Pole in the following
January.

On this occasion his approach was made from a point diametrically
opposite to the former. He very soon found himself in the middle of the
ice. He discovered within the Antarctic Circle land, to which he gave
the name of _Adelia's Land_. The long and lofty cliffs of this island or
continent he describes as being surrounded by a belt of islands of ice
at once numerous and threatening. D'Urville did not hesitate to navigate
his corvettes through the middle of the band of enormous icebergs which
seemed to guard the Pole and forbid his approach to it. For some moments
his vessels were so surrounded that they had reason to fear, from moment
to moment, some terrible shock, some irreparable disaster. In addition
to this, the sea produces around these floating icebergs, eddies, which
were not unlikely to draw on the ship to the destruction with which it
was threatened at every instant. It was in passing at their base that
D'Urville was able to judge of the height of these icy cliffs. "The
walls of these blocks of ice," he says, "far exceed our masts and
riggings in height; they overhang our ships, whose dimensions seem
ridiculously curtailed. We seem to be traversing the narrow streets of
some city of giants. At the foot of these gigantic monuments we perceive
vast caverns hollowed by the waves, which are engulfed there with a
crashing tumult. The sun darts his oblique rays upon the immense walls
of ice as if it were crystal, presenting effects of light and shade
truly magical and startling. From the summit of these mountains,
numerous brooks, fed by the melting ice produced by the summer heat of a
January sun in these regions, throw themselves in cascades into the icy
sea.

"Occasionally these icebergs approach each other so as to conceal the
land entirely, and we only perceive two walls of threatening ice, whose
sonorous echoes send back the word of command of the officers. The
corvette which followed the _Astrolabe_ appeared so small, and its masts
so slender, that the ship's crew were seized with terror. For nearly an
hour we only saw vertical walls of ice." Ultimately they reached a vast
basin, formed on one side by the chain of floating islands which they
had traversed, and on the other by high land rising three and four
thousand feet, rugged and undulating on the surface, but clothed over
all with an icy mantle, which was rendered dazzlingly imposing in its
whiteness by the rays of the sun. The officers could only advance by the
ship's boats through a labyrinth of icebergs up to a little islet lying
opposite to the coast. They touched the land at this islet; the French
flag was planted, possession was taken of the new continent, and, in
proof of possession, some portions of rock were torn from the scarped
and denuded cliffs. These rocks are composed of quartzite and gneiss.
The southern continent, therefore, belongs to the primitive formation,
while the northern region belongs in great part to the transition, or
coal formation. According to the map of Adelia's Land, traced by
D'Urville over an extent of thirty leagues of country, the region is one
of death and desolation, without any trace of vegetation.

A little more to the north, the French navigator had a vague vision on
the white lines of the horizon of another land, which he named _Côte
Clarie_, or Coast Clear, the existence of which was soon confirmed by
the American expedition under Commodore Wilkes. This officer has
explored the southern land on a larger scale than any other navigator,
but he suffered himself to be led into error by the dense fogs of the
region, and has laid down coast lines on his map where Sir James Boss
subsequently found only open sea--an error which has very unjustly
thrown discredit on the whole expedition.

The English expedition entered this region on Christmas Day, 1840, which
was passed by Ross in a strong gale, with constant snow or rain. Soon
after, the first icebergs were seen, having flat tabular summits, in
some instances two miles in circumference, bounded on all sides by
perpendicular cliffs. On New Year's Day, 1841, the ships crossed the
Antarctic Circle, and reached the edge of the pack ice, which they
entered, after skirting it for several days. On the 5th, the pack was
passed through, amid blinding snow and thick fog, which on clearing away
revealed an open sea, and on the 11th of January land was seen directly
ahead of the ships. A coast line rose in lofty snow-covered peaks at a
great distance. On a nearer view, this coast is thus described: "It was
a beautifully clear evening, and two magnificent ranges of mountains
rose to elevations varying from seven thousand to ten thousand feet
above the level of the sea." The glaciers which filled their intervening
valleys, and which descended from near the mountain summits, projected
in many places several miles into the sea, and terminated in lofty
perpendicular cliffs. In a few places the rocks broke through their icy
covering, by which alone we could be assured that lava formed the
nucleus of this, to all appearance, enormous iceberg. This antarctic
land was named Victoria Land, in honour of the Queen. It was coasted up
to latitude seventy-eight degrees south, and near to this a magnificent
volcanic mountain presented itself, rising twelve thousand feet above
the level of the sea, which emitted flame and smoke in splendid
profusion. The flanks of this gigantic mountain were clothed with snow
almost to the mouth of the crater from which the flaming smoke issued.
At a short distance, Ross discovered the cone of an extinct, or, at
least, inactive volcano nearly as lofty. He gave to these two volcanoes
the names of his vessels, _Erebus_ and _Terror_ (Fig. 9)--names
perfectly in harmony with the surrounding desolation. The ice-covered
cliffs rose about a hundred and ninety feet high, and appear to be about
three hundred feet deep, soundings being found at about four hundred
fathoms. In the distance, towards the south, a range of lofty mountains
were observed, which Ross named _Mount Parry_, in honour of his old
commander. When Ross retraced his steps, the expedition had advanced as
far as the seventy-ninth degree of south latitude.

[Illustration: Fig. 9. Mounts Erebus and Terror.]

       *       *       *       *       *

It may be said of polar countries, that they form a transition state
between land and sea, for water is always present, although in a solid
state; the surface is always at a very low temperature; snow does not
melt as it falls, and the sea is thus sometimes covered with a
continuous sheet of frozen snow; sometimes with enormous floating blocks
of ice which are driven by the currents. Meeting with these floating
masses of ice is one of the dangers of polar navigation. Captain
Scoresby has given a very detailed description of the different kinds of
ice met with in the Arctic Seas. The ice-fields of this writer form
extensive masses of solid water, of which the eye cannot trace the
limits, some of them being thirty-five leagues in length and ten broad,
with a thickness of seven to eight fathoms; but generally these
ice-fields rise only four to six feet above the water, and reach from
three to four fathoms beneath the surface. Scoresby has seen these
ice-fields forming in the open sea. When the first crystals appear, the
surface of the ocean is cold enough to prevent snow from melting as it
falls. On the approach of congelation the surface solidifies, and seems
as if covered with oil; small circles are formed, which press against
each other, and are finally soldered together until they form a vast
field of ice, the thickness of which increases from the lower surface.

The water produced from melted ice is perfectly fresh--the result of a
well-known physical cause. When a saline solution like sea water is
congealed by cold, pure water alone passes into the solid state, the
saline solution becomes more concentrated, increases in density, and,
sinking to the bottom, remains liquid. Blocks of ice, therefore, in the
Polar Seas, are always available for domestic use. There are, however,
salt blocks of ice, which are distinguished from fresh-water ice by
their opaqueness and their dazzling white colour: this saltness is due
to the sea water retained in its interstices. Scoresby amused himself
sometimes by shaping lenses of ice, with which he is said to have set
fire to gunpowder, much to the astonishment of his crew.

The ice-fields, which are formed in higher latitudes, are driven towards
the south by winds and currents, but sooner or later the action of the
waves breaks them up into fragments. The edges of the broken icebergs
are thus often rising and continually changing: these asperities and
protuberances are called _hummocks_ by English navigators; they give to
the polar ice an odd, irregular appearance. Hummocks form themselves of
the stray, broken icebergs which come in contact with each other at
their edges, and thus form vast rafts, the pieces of which may exceed a
hundred yards in length.

When these icebergs are separated by open spaces, through which vessels
can be navigated, the pack ice is said to be open. But it often happens
that mountains of ice occur partly submerged, where one edge is retained
under the principal mass, while the other is above the water. Scoresby
once passed over a _calf_, as English mariners call these icy mountains,
but he trembled while he did so, dreading lest it should throw his
vessel, himself, and crew into the air before he could pass it. The
aspect of the ice-fields varies in a thousand ways. Here it is an
incoherent chaos resembling some volcanic rocks, with crevices in all
directions, bristling with unshapely blocks piled up at random; there it
is a strongly-marked plain, an immense mosaic formed of vast blocks of
ice of every age and thickness, the divisions of which are marked by
long ridges of the most irregular forms; sometimes resembling walls
composed of great rectangular blocks, sometimes resembling chains of
hills, with great rounded summits.

In the spring, when a thaw sets in, and the fields begin to break up,
the pieces of light ice which unite the great blocks into unique masses
are the first to melt; the several blocks then separate, and the motion
of the water soon disperses them, and the imprisoned ships find a free
passage. But a day of calm is still sufficient to unite the dispersed
masses, which oscillate and grind against each other with a strange
noise, which sailors compare to the yelping of young dogs.

When a ship is shut up in one of these floating ice-fields, inexplicable
changes sometimes occur in the vast incoherent aggregations. Vessels,
which think themselves immovable, are found in a few hours to have
completely reversed their positions. Two ships shut in at a short
distance from each other were driven many leagues without being able to
perceive any change in the surrounding ice. At other times ships are
drawn with the floating ice-fields, like the white bears, who make long
voyages at sea upon these monster vehicles. In 1777 the Dutch vessel,
the _Wilhelmina_, was driven with some other whaling ships from eighty
degrees north back to sixty-two degrees, in sight of the Iceland coast.
During this terrible journey the ships were broken up one after the
other. More than two hundred persons perished, and the remainder reached
land with difficulty.

Lieutenant De Haven, navigating in search of Sir John Franklin, was
caught in the ice in the middle of the channel in Wellington Strait.
During the nine months which he remained in captivity, he drifted nearly
thirteen hundred miles towards the south; and the ship _Resolute_,
abandoned by Captain Kellet in an ice-field of immense extent, was
drifted towards the south with this vast mass to a much greater
distance.

Some curious speculations are hazarded by Dr. Maury, arising out of his
investigations of winds and currents, facts being revealed which
indicate the existence of a climate, mild by comparison, within the
Antarctic Circle. These indications are a low barometer, a high degree
of aerial rarefaction, and strong winds from the north. "The winds," he
says, "were the first to whisper of this strange state of things, and to
intimate to us that the Antarctic climates are in winter very unlike the
Arctic for rigour and severity." The result of an immense mass of
observation on the polar and equatorial winds reveals a marked
difference in atmospherical movements north, as compared with the same
movements south of the Equator; the equatorial winds of the northern
hemisphere being only in excess between the tenth and thirteenth
parallel, while those of the southern hemisphere are dominant over a
zone of forty-five degrees, or from thirty-five degrees south to ten
degrees north.

"The fact that the influence of the polar indraught upon the winds
should extend from the Antarctic to the parallel of forty degrees south,
while that from the Arctic is so feeble as scarcely to be felt in fifty
degrees north, is indicative enough as to the difference in degree of
aerial rarefaction over the two regions. The significance of the fact is
enhanced by the consideration that the 'brave west winds,' which are
bound to the place of greatest rarefaction, rush more violently and
constantly along to their destination than do the counter-trades of the
northern hemisphere. Why should these polar-bound winds differ so much
in strength and prevalence, unless there be a much more abundant supply
of caloric, and, consequently, a higher degree of rarefaction, at one
pole than at the other?"

That this is the case is confirmed by all known barometrical
observations, which are very much lower in the Antarctic than in the
Arctic, and Dr. Maury thinks this is doubtless due to the excess in
Antarctic regions of aqueous vapour and this latent heat.

"There is rarefaction in the Arctic regions. The winds show it, the
barometer attests it, and the fact is consistent with the Russian theory
of a Polynia in polar waters. Within the Antarctic Circle, on the
contrary, the winds bring air which has come over the water for the
distance of hundreds of leagues all around; consequently, a large
portion of atmospheric air is driven away from the austral regions by
the force of vapour."



CHAPTER III.

LIFE IN THE OCEAN.

    "See what a lovely shell, small and pure as a pearl,
    Frail, but a work divine, made so fairly well,
    With delicate spore and whorl, a miracle of design."

    TENNYSON.


"The appearance of the open sea," says Frédol, from whose elegant work
this chapter is chiefly compiled, "far from the shore--the boundless
ocean--is to the man who loves to create a world of his own, in which he
can freely exercise his thoughts, filled with sublime ideas of the
Infinite. His searching eye rests upon the far-distant horizon. He sees
there the ocean and the heavens meeting in a vapoury outline, where the
stars ascend and descend, appear and disappear in their turn. Presently
this everlasting change in nature awakens in him a vague feeling of that
sadness 'which,' says Humboldt, 'lies at the root of all our heartfelt
joys.'"

Emotions of another kind and equally serious are produced by the
contemplation and study of the habits of the innumerable organized
beings which inhabit the great deep. In fact, that immense expanse of
water, which we call the sea, is no vast liquid desert; life dwells in
its bosom as it does on dry land. Here this mystery reigns supreme in
the midst of its expansions, luxuries, and agitations. It pleases the
Creator. It is the most beautiful, the most brilliant, the noblest, and
the most incomprehensible of His manifestations. Without life, the world
would be as nothing. The beings endowed with it transmit it faithfully
to other beings, their children, and their successors, which will be,
like them, the depositaries of the same mysterious gift; the marvellous
heritage thus traverses years and hundreds of years without losing its
powers; the globe is redolent with the life which has been so
bounteously distributed over it. In the words of Lamartine, "We know
what produces life, but we know not what it is;" and this ignorance is
perhaps the powerful attraction which provokes our curiosity and excites
us to study.

Every living being is animated by two principles, between which a silent
but incessant combat is being carried on--_life_, which assimilates, and
_death_, which disintegrates. At first, life is all powerful--it lords
it over matter; but its reign is limited. Beyond a certain point its
vigour is gradually impaired; with old age it decays; and is finally
extinguished with time, when the chemical and physical laws seize upon
it, and its organization is destroyed. But the elements, though inert at
first, are soon reanimated and occupied with a new life. Every plant,
every animal is bound up with the past, and is part of the future, for
every generation which starts into life is only the corollary upon that
which expires, and the prelude of another which is about to be born.
Life is the school of death; death is the foster-mother of life.

Life, however, does not always exhibit itself at the moment of its
formation. It is visible later, and only after other phenomena. In order
to develope itself, a suitable soil or other medium must be prepared,
and other determinate physical and chemical conditions provided. The
presence and diffusion of living beings are no chance products; they
follow rigorously an order of law. Speaking of the higher forms of
animal life, the Duke of Argyll says, in his able and satisfactory work,
"The Reign of Law,"--"In all these there is an observed order in the
most rigid scientific sense, that is, phenomena in uniform connexion and
mutual relations which can be made, and are made, the basis of
systematic classification. These classifications are imperfect, not
because they are founded on ideal connexions where none exist, but only
because they fail in representing adequately the subtle and pervading
order which binds together all living things."

The knowledge of fossils has thrown great light upon the regular and
progressive development of organization. The evolution of living beings
seems to have commenced with the more rudimentary forms; the more
ancient rocks, until very recently, had revealed no traces of life, and
what has been revealed tends to confirm this view. In the Cambrian rocks
of Bray Head, county Wicklow, the _Oldhamia_ is a zoophyte of the
simplest organization, and the Rhizapods found near the bottom of the
Azoic rocks of Canada are the lowest form of living types; and it is
only in beds of comparatively recent formation that complex organization
exists. Vegetables first show themselves, and even among these the
simplest forms have priority. Animals afterwards appear, which, as we
have seen, belong to the least perfect classes. The combinations of
life, at first simple, have become more and more complex, until the
creation of man, who may be considered the masterpiece of organization.

If we expose a certain quantity of pure water to the light and air in
the spring, we should soon see it producing shades of a yellowish or
greenish colour. These spots, examined through the microscope, reveal
thousands of vegetable agglomerates. Presently thousands of animalcules
appear, which swim about among the floating masses, nourishing
themselves with its substance. Other animalcules then appear, which, in
their turn, pursue and devour the first.

In short, life transforms inanimate into organized matter. Vegetables
appear first, then come herbivorous animals, and then come the
carnivorous. Life maintains life. The death of one gives food and
development to others, for all are bound up together--all assist at the
metamorphoses continually occurring in the organic as in the mineral
world, the result being general and profound harmony--harmony always
worthy of admiration. The Creator alone is unchangeable, omnipotent, and
permanent; all else is transition.

       *       *       *       *       *

The inhabitants of the water are much more numerous than those of the
solid earth. "Upon a surface less varied than we find on continents,"
says Humboldt, "the sea contains in its bosom an exuberance of life of
which no other portion of the globe could give us any idea. It expands
in the north as in the south; in the east as in the west. The seas,
above all, abound with it; in the bosom of the deep, creatures
corresponding and harmonizing with each other sport and play. Among
these especially the naturalist finds instruction, and the philosopher
subjects for meditation. The changes they undergo only impress upon our
minds more and more a sentiment of thankfulness to the Author of the
universe."

Yes, the ocean in its profoundest depths--its plains and its mountains,
its valleys, its precipices, even in its ruins--is animated and
embellished by innumerable organized beings. These are at first plants,
solitary or social, erect or drooping, spreading into prairies, grouped
in patches, or forming vast forests in the oceanic valleys. These
submarine forests protect and nourish millions of animals which creep,
which run, which swim, which sink into the sands, attach themselves to
rocks, lodge themselves in crevices, which construct dwellings for
themselves, which seek for or fly from each other, which pursue or
fight, caress each other lovingly, or devour each other without pity.
Charles Darwin truly remarks somewhere that our terrestrial forests do
not maintain nearly so many living beings as those which swarm in the
bosom of the sea. The ocean, which for man is the region of asphyxia and
death, is for millions of animals the region of life and health: there
is enjoyment for myriads in its waves; there is happiness on its banks;
there is the blue above all.

       *       *       *       *       *

The sea influences its numerous inhabitants, animal or vegetable, by its
temperature, by its density, by its saltness, by its bitterness, by the
never-ceasing agitation of its waves, and by the rapidity of its
currents.

We have seen in preceding chapters that the sea only freezes under
intense cold, and then only at the surface, and that at the depth of
five hundred fathoms the same permanent temperature exists in all
latitudes. On the other hand, it is agreed that the agitations produced
by the most violent storms are never felt beyond the depth of twelve or
thirteen fathoms. From this it follows that animals and vegetables, by
descending more or less, according to the cold or disturbing movements,
can always reach a medium which agrees with their constitutions.

The hosts of the sea are distinguished by a peculiar softness. Certain
pelagic plants present only a very weak, feeble consistence; a great
number are transformed by ebullition into a sort of jelly. The flesh of
marine animals is more or less flaccid; many seem to consist of a
diaphanous mucilage. The skeleton of the more perfect species is more or
less flexible and cartilaginous; and it rarely attains, as to weight and
consistency, the strength of bone exhibited by terrestrial vertebrate
animals. Nevertheless, both the shells and coral produced in the bosom
of the ocean are remarkable for their stony solidity. Among marine
bodies, in short, we find at once the softest and hardest of organized
substances.

The separation of organized beings, nourished by the ocean, is
subjected to certain fixed laws. We never find on the coast, except by
evident accident, the same species that we meet with far from the shore;
nor on the surface, creatures whose habits lead them to hide in the
depths of ocean. What immense varieties of size, shape, form, and
colour, from the nearly invisible vegetation which serves to nourish the
small zoophytes and mollusks, to the long, slender algæ of fifty--and
even five hundred--yards in length! How vast the disparity between the
microscopic infusoria and the gigantic whale!

"We find in the sea," says Lacepede, "unity and diversity, which
constitute its beauty; grandeur and simplicity, which give it sublimity;
puissance and immensity, which command our wonder."

In the following pages we shall figure and describe many inhabitants of
the sea; but how many remain still to figure and describe! During more
than two thousand years research has been multiplied, and succeeded by
research without interruption. "But how vast the field," as Lamarck
observes, "which Science has still to cultivate, in order to carry the
knowledge already acquired to the degree of perfection of which it is
susceptible!"

       *       *       *       *       *

"When the tide retires from the shore, the sea leaves upon the coast
some few of the numberless beings which it bears in its bosom. In the
first moments of its retreat, the naturalist may collect a crowd of
substances, vegetable and animal, with their various characteristic
colours and properties. The inhabitants of the coast find there their
food, their commerce, and their occupations. At low water the nearest
villages and hamlets send their contingents, old and young, men, women,
and children, to the harvest. Some apply themselves to gathering the
riband seaweed (_Zostera_), the membranous _Ulva_, the sombre brown
_Fucus vesiculosus_, formerly a source of great wealth to the dwellers
by the sea, being then much used in making kelp; others gather the small
shells left on the sands; boys mount upon the rocks in search of whelks
(_Buccinum_), mussels (_Mytilus_), detach limpets (_Patella_), and other
edible marine animals, from the rocks to which they have attached
themselves. On some coasts, shells, as _Mactra_, _Cytheria_, and
_Bucardium_, are sought for their beauty. By turning the stones, or by
sounding the crevices of the rocks with a hook at the end of a lath,
polypes and calmars are sometimes surprised--sometimes even sea and
conger eels, which have sought refuge there; while the pools, left here
and there by the retiring tide, are dragged by nets of very small mesh,
in which the smaller crustaceous mollusks and small fish are secured."

       *       *       *       *       *

In the Mediterranean and other inland seas, where the tide is almost
inappreciable, there exist a great number of animals and vegetables
belonging to the deep sea, which the waves or currents very rarely leave
upon the sea shore. There are others so fugitive, or which attach
themselves so firmly to the rocks, that we can watch them only in their
habitats. It is necessary to study them floating on the surface of the
waves, or in their mysterious retirements. Hence the necessity that
naturalists should study the living productions of the salt water even
in the bosom of the ocean, and not on the sea shore.

The means generally employed for this purpose is a drag-net,
sounding-line, and other engines suitable for scraping the bottom, and
breaking the harder rocks. In a voyage which Milne Edwards made to the
coast of Sicily, he formed the idea of employing an apparatus invented
by Colonel Paulin, which consisted of a metallic casque provided with a
visor of glass, and consequently transparent, which fixed itself round
the neck by means of a copper collar made water-tight by stuffing--a
diving-bell, in short, in miniature. It communicated with an air-pump by
means of a flexible tube. Four men were employed in serving the pump,
two exercising it while the other two rested themselves. Other men held
the extremity of a cord, which was passed over a pulley attached at a
higher elevation, and enabled them to hoist up the diver with the
necessary rapidity in emergencies. A vigilant observer held in his hand
a small signal cord. The immersion of the diver was facilitated by heavy
leaden shoes, which assisted him at the same time to maintain his
vertical position at the bottom. M. Edwards made the descent with this
apparatus in three fathoms water with perfect success. He was thus
enabled to study, in their most hidden and most inaccessible retreats,
the radiate animals, mollusks, crustaceans, and annelids, especially
their larvæ and eggs, and by his descriptions to contribute most
essentially to make known the functions, manners, and mode of
development of certain inhabitants of the sea, whose sojourn and habits
would seem to sequestrate them for ever from our observation.

Another and easier mode of studying the living creatures sheltered by
the sea was first suggested by M. Charles des Moulins of Bordeaux, in
1830. The _aquarium_, which is charged with fresh or salt water,
according to the beings it is intended to contain, serves the same
purpose for the inhabitants of the deep which the aviary does for the
birds of the air--cages of glass being used in place of iron wire or
wicker-work, and water in place of atmospheric air.

When a globe is filled with fresh water, and with mollusks, crustaceans,
or fishes, it is observed, after a few days, that the water loses its
transparency and purity, and becomes slightly corrupt. It necessarily
follows that the water must be changed from time to time. Changing the
water, however, causes much suffering, and even death to the animals.
Besides, the new water does not always present the same composition, the
same aeration, or the same temperature with that which is replaced. To
obviate this defect, and taking a leaf out of Nature's book, M. Moulins
proposed to put into the vase a certain number of aquatic plants
floating or submerged--duckweed, for example--which would act upon the
water in a direction inverse to that of the animals inhabiting it. It is
known that vegetables assimilate carbon, while decomposing the carbonic
acid produced by the respiration of animals, thus disengaging the oxygen
indispensable to animal life. In this simple manner was the necessary
change of water obviated. The same happy idea has been successfully
applied to salt water, and aquariums for salt-water plants and animals
have been proposed on a great scale. That of the Zoological Gardens of
Paris, in the Bois de Boulogne, inaugurated in 1861, is perhaps the
largest in the world. It is a solid stone building of fifty yards in
length by about twelve broad, presenting a range of forty reservoirs of
Angers slate, running north and south. The reservoirs are nearly
cubical, presenting in front the strong glass of Saint Gobain, which
permits of the interior being seen. They are lighted from above; but the
light is weak, greenish, uniform, and consequently mysterious and
gloomy, giving a pretty exact imitation of the submarine light some
fathoms down. Each reservoir contains about two hundred gallons of
water. It is furnished with rocks disposed a little in the form of an
amphitheatre, and in a picturesque manner. Upon the rocks various
species of marine vegetables are planted. The bottom is of shingle,
gravel, and sand, in order to give certain animals a sufficiently
natural retreat.

Ten of these reservoirs are intended for marine animals. The water
employed is never changed, but it is kept in continual agitation by
circulation, produced by a current of water led from the great pipe
which feeds the Bois de Boulogne. This water, being subjected to a
strong pressure, compresses a certain portion of air, which, being
permitted to act on a portion of the sea water contained in a closed
cylinder placed below the level of the aquarium, makes it ascend, and
enter with great force into a reservoir, into which it is thrown from a
small jet. The sea water thus pressed absorbs a portion of the air,
which is drawn with it into the reservoir. A tube placed in a corner of
the reservoir receives the overflow, and conducts it into a closed
carbon filter, whence it passes into a gravelly underground reservoir,
returning again to the closed cylinder. The water is once more subjected
to the pressure of air, and again ascends to the aquarium. The cylinder
being underground, a temperature equal to about sixteen degrees Cent.,
which is nearly the uniform temperature of the ocean, is easily
maintained. During winter, the aquarium is heated artificially.



CHAPTER IV.

ZOOPHYTES.

    "Nature is nowhere more perfect than in her smaller works."
    "Natura nusquam magis quàm in minimis tota est."

    PLINY.


It will not be out of place here to offer some remarks on animals in
general, including the whole kingdom as well as the great divisions
which form the subject of this particular volume. But considering the
vastness of the subject, and our imperfect knowledge of the whole animal
series as a subject of study, nothing is more difficult than to seize
upon the real analogies between beings of types so varied,--of
organizations so dissimilar. The arrangements which naturalists have
established in order to study and describe animals--the divisions,
classes, orders, families, genera, and species--are admirable
contrivances for facilitating the study of creatures numerous as the
sands of the sea shore. Without this precious means of logical
distribution, the individual mind would recoil before the task of
describing the innumerable phalanges of contemporary animal life. But
the reader must never forget that these methodical divisions are pure
fictions, due to human invention: they form no part of nature; for has
not Linnæus told us that nature makes no leaps, _natura non facit
saltus_? Nature passes in a manner almost insensibly from one stage of
organization to another, altogether irrespective of human systems.

Moreover, when we come to watch the confines of the animal and vegetable
kingdom, we realise how difficult it is to seize the precise line of
demarcation which separates the great kingdoms of Nature. We have seen
in the "Vegetable World" germs of the simplest organization, as in the
Cryptogamia, spores, as in the Algæ, and fruitful corpuscles, as in the
Mosses, which seem to be invested with some of the characteristics of
animal life, for they appear to be gifted with organs of locomotion,
namely, vibratile cilia, by means of which they execute movements which
are to all appearance quite voluntary. Side by side with these are
vegetable germs and fecundating corpuscles, known as _antherozoides_
among the Algæ, Mosses, and Ferns, which, when floating in water, go and
come like the inferior animals, seeking to penetrate into cavities,
withdrawing themselves, returning again, and again introducing
themselves, and exhibiting all the signs of an apparent effort. Let us
compare the Infusoria, or even the Polypi and Gorgons, with these
shifting vegetable organisms, and say if it is easy to determine,
without considerable study, which is the plant and which the animal. The
precise line of demarcation which it is so desirable to establish
between the two kingdoms of Nature is indeed difficult to trace.

The word _zoophyte_, to which this comparison introduces us, seems very
happily applied: it is derived from the Greek word ζῶον, animal, and
φυτὸν, _plant_; and is, as it seems to us, quite worthy of being
retained in Science, because it consecrates and materialises, so to
speak, a sort of fusion between the two kingdoms of Nature at their
confines. Let us guard ourselves, however, from carrying this idea too
far, and, upon the faith of a happy word, altering altogether the true
relations of created beings. In adopting the name _zoophyte_, to
indicate a great division of the animal kingdom, the reader must not
imagine that there is any ambiguity about the creatures designated, or
that they belong at once to both kingdoms, or that they might be ranged
indifferently in the one or the other. Zoophytes are animals, and
nothing but animals; the justification for using a designation which
signifies animal-plant is, that many of them have an exterior
resemblance to plants; that they divide themselves by offshoots, as some
plants do, and are sometimes crowned with organs tinted with lively
colours, like some flowers.

This analogy between plants and zoophytes is nowhere more apparent than
in the coral. Rooted in the soil and upon rocks, the form of its
branches many times subdivided, above all, the coloured appendages which
at certain periods so closely resemble the corolla of a flower, have all
the form and appearance of plants. Until the eighteenth century most
naturalists classed the coral as Linnæus did, without the least
hesitation, with analogous creations in the vegetable world. Réaumur
long contended for the contrary opinion; but it is only in our day that
the animal nature of the coral is satisfactorily established. The _sea
anemone_ may be cited as another striking example of the resemblance
borne by certain inferior organisms to vegetables. We hold, then, that
we are justified in using the word _zoophyte_ to designate the beings
which now occupy our attention.

       *       *       *       *       *

We shall not surprise our readers by telling them that the structure of
the zoophyte, especially in its inferior orders, is excessively simple.
They are the first steps in the scale of animal life, and in them a
purely rudimentary organization was to be expected. In these
beings--true types of animal life--the several parts of the body, in
place of being disposed in pairs on each side of its longitudinal plane,
as occurs in animals of a higher organization, are found to radiate
habitually round an axis or central point, and this whether in its adult
or juvenile state. Zoophytes have not generally an articulate skeleton,
either exterior or interior, and their nervous system, where it exists,
is very slightly developed. The organs of the senses, other than those
of touch, are altogether absent in the greater part of beings which
belong to this, the lowest class of the last division of the animal
kingdom.

Several questions arise here: Has the zoophyte sentiment, feeling,
perception? Has it consciousness, sense, sensibility? The question is
insoluble; it is an abyss of obscurity. The coral, or rather the
aggregation of living beings which bear the name, are attached to the
rock which has seen their birth, and which will witness their death: the
infusoria, of microscopic dimensions, which revolve perpetually in a
circle infinitesimally small; the Amoebæ, the marvellous Proteus, which
in the space of a minute changes its form a hundred times under the
surprised eyes of the observer, are, in truth, mere atoms charged with
life. Yet all these beings have an existence to appearance purely
vegetative. In their obscure and blind impulse, have they consciousness
or instinct? Do they know what takes place at the three-thousandth part
of an inch from their microscopic bodies? To the Creator alone does the
knowledge of this mystery belong.

It would be foreign to the object of this work to enter into minute
division of the innumerable creatures which swarm on the ocean and on
its confines. We shall perhaps best consult the convenience of our
readers by adopting the following simple arrangement of these animals
into

I. PROTOZOA, including the _Spongiadæ_, _Infusoria_, and _Foraminifera_.

II. POLYPIFERA, including the _Hydræ_, _Sertularia_, and _Pennatulariæ_.

III. ECHINODERMATA, or Sea-urchins and Star-fishes.

Our space will prevent our doing more than presenting to the reader in
succession the most characteristic types of each of these groups.


I. THE PROTOZOA.

The Protozoares represent animal life reduced to its most simple
expression. They are organized atoms, mere animated and moving points,
living sparks. As they are the simplest forms of animal life as regards
their structure, so also they are the smallest. Their microscopic
dimensions hide them from our view. The discovery of the microscope was
a necessary step to our becoming acquainted with these beings, whose
existence was ignored by the ancient world, and only revealed in the
seventeenth century by the discovery of the microscope. When armed with
this marvellous instrument, applied to examine the various liquid
mediums--as when Leuwenhoek, for example, applied the magnifying glass
to the inspection of stagnant water, with its infusions of macerated
vegetable and animal substances--when he scrutinized a drop of water
borrowed from the ocean, from rivers, or from lakes, he discovered there
a new world--a world which will be unveiled in these pages.

Some modern writers believe that the Protozoa is a mere _cellular
organism_, that being the principle and end of organization, such as we
find it in the cellular vegetable. According to this hypothesis, the
Protozoares would be the cellulars of the animal kingdom, as the Algæ
and Mushrooms are of the vegetable world. This idea is so far wrong,
that it has been founded upon the empire of pure theory. "In reality,"
says Paul Gervais and Van Beneden, "the animals to which we extend it
very rarely resemble elementary cellulars." The tissue of which the
bodies of the Protozoa are composed is habitually destitute of cellular
structure. They are formed of a sort of animated jelly, amorphous and
diaphanous, and have received from Dujardin the name of _Sarcoda_, or
soft-fleshed animals.

Infinitely varied in their form, the Protozoares are furnished with
_vibratile cilia_, which are organs of locomotion belonging to the lower
animals inhabiting the liquid element. Their bodies are sometimes naked,
sometimes covered with a siliceous, chalky, or membranous cuirass. They
are divided into two great classes, the _Rhizopoda_ and _Infusoria_.


SPONGIA.

The Sponge is a natural production, which has been known from times of
the highest antiquity. Aristotle, Pliny, and all other writers who
occupied themselves with natural history in ancient times, are agreed in
according to it a sensitive life. They recognize the curious fact that
the sponge evades the hand which tries to seize it, and clings to the
rocks on which it is rooted, as if it would resist the efforts made to
detach it. Pliny, Dioscorides, and their commentators, even formed the
idea that sponges were capable of feeling, that they adhered to their
native rock by special force, and that they shrunk from the hand which
tried to seize them. They even distinguished males from females.
Erasmus, however, criticising Pliny, concludes that he may pass over all
he has written upon the sponge. The sponge, in short, was to the
ancients something between a plant and an animal.

Rondelet, the friend of the celebrated Rabelais, whom the merry curate
of Meudon designated under the name of _Rondibilis_, who was himself a
physician and naturalist of Montpellier, denied at first the existence
of sensibility in sponges. He originated the idea that these productions
belonged to the vegetable world--an idea which Tournefort, Gaspard
Bauhin, Rey, and even Linnæus, in the first editions of his "Systema
Naturæ," supported by the great authority of their names. Afterwards,
influenced by the convincing labours of Trembley and some other
observers, Linnæus withdrew the sponges from the vegetable world. He
satisfied himself, in short, that certain polypiers much resembled
sponges in the nature of their parenchyma, and that, on the other hand,
the assimilation of sponges with plants was not such as could be
maintained. Neuremberg, Peyssonnel, and Trembley maintain the animal
nature of sponges, and their views are adopted by Linnæus, Guettard,
Donati, Lamouroux, and Ehrenberg on the Continent, and by Ellis,
Fleming, and Grant in England. They live at the bottom of the seas in
five to twenty-five fathoms of water, among the clefts and crevices of
the rocks, always adhering and attaching themselves, not only to
inorganic bodies, but even growing on vegetables and animals, spreading,
erect, or pendent, according to the body which supports them and their
natural habit.

The power of fixing themselves to other objects, which certain animals
possess, is very singular. Nevertheless, it is certain that whole tribes
exist consisting of innumerable strictly adherent species, which live
and die attached to some rock or other object; and among these are all
polypiers, such as the sponges and corallines. It follows that they are
wholly dependent on external agencies for their means of existence. "The
poor little creatures," says Alfred Frédol, "receive their nourishment
from the wave which washes past them; they inhale and respire the bitter
water all their lives; they are insensible to that which is only the
hundredth part of an inch from their mouth."

In the months of April and May, these animalcules engender germs, round,
yellow, or white, whence proceed certain ovoid granular embryos
furnished towards their largest extremity with small vibratile cilia.
They are thrown off by the currents, which serve as a stomach, and form
swarms of larvæ round the polypier. They swim about with a gliding wavy
motion, and when they have been some time in the water they usually come
to the surface; but they are also often carried off by the current.
During two or three days they seem to seek a convenient place to fix
themselves. Once fixed, the larvæ loses the cilia, spreads itself out,
and takes the form of a flattened gelatinous disk.

Its interior organization consists of contractile cellules and numerous
spiculæ--"a tribe," says Gosse, "of the most debateable forms of life,
long denied a right to stand in the animal ranks at all, and even still
admitted there doubtingly and grudgingly by some excellent naturalists.
Yet such they certainly are, established beyond reasonable controversy
as true and proper examples of animal life."

It may, then, be safely asserted that all naturalists are now satisfied
of the animal nature of sponges, although they represent the lowest and
most obscure grade of animal existence, and that so close to the
confines of the vegetable world, that it is difficult in some species to
determine whether they are on the one side or the other. "Several of
them, however," says Mr. Gosse, "if viewed with a lens under water while
in a living state, display vigorous currents constantly pouring forth
from certain orifices; and we necessarily infer that the water thus
ejected must be constantly taken in through some other channel. On
tearing the mass open, we see that the whole substance is perforated in
all directions by irregular canals, leading into each other, of which
some are slender, and communicate with the surface by minute but
numerous pores, and others are wide, and open by ample orifices; through
the former the water is admitted, through the latter it is ejected." It
is not to be denied, however, that these beings constitute, in spite of
investigations of modern naturalists, a group still somewhat
problematical, and still very imperfectly known as regards their
internal organization.

Sponges are masses of a light elastic tissue, which is, at the same
time, resistant, full of air-cells, and with much varied exterior
arrangements. Nearly three hundred species are known, the different
appearances of which have been characterised by names more or less
singular. There is, for instance, the Feather Sponge, the Fan Sponge,
the Bell, the Lyre, the Trumpet, the Distaff, the Peacock Tail, and
Neptune's Glove.

There are river sponges and sea sponges.

The first are irregular and arenaceous masses, which pile themselves
upon plants and solid bodies immerged in fresh water. Such are the
_spongilles_, upon which anatomic and embryonic observations have very
frequently been made in relation to the group more immediately under
consideration.

The second is found in almost every sea; especially are they found in
the Mediterranean, the Red Sea, and the Mexican Gulf. Affecting warm and
quiet waters, they attach themselves to bold and rugged rocks at depths
ranging from five to twenty-five fathoms. They are erect, pendent, or
spreading, according to their form or position. Fig. 10, drawn from
Nature, represents a very remarkable form of sponge, which was fished up
in sixty fathoms.

The sponge is very common in the Mediterranean and round the Grecian
Archipelago, and is known vulgarly under the name of the Marine
Mushroom, the Sailor's Nest, and the fine soft sponge of Syria. It is a
mass more or less rounded, covered with a mucous bed, glutinous above,
formed of a light elastic but resisting tissue full of gaps, and
riddled with air-cells. This tissue is formed of delicate flexible
fibres, uniting in all directions by anastomosis, but presenting
numerous pores, which are formed by what is termed osculation, having
irregular _conduits_ which connect them. In this tissue certain very
small solid bodies are discovered, named _spiculæ_. The _spiculæ_ are
siliceous or calcareous in their nature, varying according to the
species, and sometimes varying even in the same species. Some of these
resemble needles, others are pin-like, and others again resemble very
small stars.

[Illustration: Fig. 10. Spongia, half the natural size, attached to its
rocky bed.]

The physiological function of those tubes and orifices which present
themselves on all parts of the sponge has been interpreted in various
ways. Ellis, writing in 1765, supposes that they were the orifices of
the cells occupied by the polypi. In 1816, Lamarck still advocated this
opinion; and even now we find the observer, whose notes M. Frédol has
edited with so much judgment, asserting that "the inhabitants of the
sponge are a species of fleeting, transparent, gelatinous tube,
susceptible of extension and contraction; young polypes, as we may call
them, without consistence, without cilia; incipient polypes, in short,
of very simple but sufficient organization. The animalcule of the sponge
is a stomach, without arms, very simple, very elementary--in short, an
animal all stomach!"

This mode of considering the sponge is not conformable to the views of
the leaders of modern science, however. Mr. Milne Edwards, for instance,
in place of seeing in the sponge a collection of united beings, forming
as it were a colony, considers each to be an isolated being, an unique
individual. The innumerable canals by which the sponge is traversed,
according to that author, are at once the digestive organs and breathing
pores of the zoophyte. The vibratile cilia are necessary to the renewed
aeration of the water required as a respiratory fluid in the interior
canals of the sponge. The currents in these channels have one constant
direction. The water penetrates the sponge by numerous orifices of
minute dimensions and irregular disposition; it traverses channels in
the body of the zoophyte, which reunite somewhat like the root of a
plant, in order to constitute the trunk and increase its substance;
finally, the water makes its escape by special openings. According to
this view, the channels of the sponge have a kind of cumulative
physiology, performing the two functions of digestion and respiration.
The rapid currents of aerated water which traverse them lead into them
the substances necessary to the nourishment of these strange creatures,
rejecting all excremental matter. At the same time, the walls of these
canals present a large absorbing surface which separates the oxygen with
which the water is charged, and disengages the carbonic acid which
results from respiration.

Sponges contain true eggs, from which embryo polyps are produced; these
have not cilia at first. In the interior of these eggs the contractile
cellules have their birth; then the spiculæ; and when they are finally
covered with the vibratile cilia, aided by them these larvæ of ovoid
form swim, or rather glide, through the water. The species of infusoria
born of the sponge resemble the larvæ of various polypes at the moment
they issue from the egg. "They soon attach themselves to some foreign
body," says Mr. Milne Edwards, "and become henceforth immovable; no
longer giving signs either of sensibility or of contractibility, while
in their enlargement they are completely transformed. The gelatinous
substance of their bodies is channeled and riddled with holes--the
fibrous framework is completed--the sponge is formed."

We may add, however, that other zoologists, and among them MM. Paul
Gervais and Van Beneden, take a different view of the development of the
sponges, and Dr. Johnston omits them altogether from his great work on
"British Zoophytes." "If they are not the production of polypi," he
says, "the zoologist who retains them in his province must contend that
they are individually animals, an opinion to which I cannot assent,
seeing that they have no animal structure or individual organs, and
exhibit not one function usually supposed to be characteristic of the
animal kingdom." Gervais and Van Beneden consider, as Milne Edwards
does, that the embryos are at first movable, then fixed, many of them
uniting together, and melting, as it were, into one common colony, which
become a sponge, such as we see it. An isolated embryo might also, by
throwing out germs, produce a similar colony, which would thus become a
product of agamous generation. Thus it appears that Science is far from
being settled in its views as to the organization and development of
these obscure and complex formations; nor is it more advanced in its
knowledge of the duration of life and the quickness of growth in
sponges. It is agreed, however, on one point--namely, that the
sponge-fisher may return to the same fishing-ground after three years
from the last fishing. At the present time sponge-fishing takes place
principally in the Grecian Archipelago and the Syrian _littoral_. The
Greeks and Syrians sell the product of their fishing to the Western
nations, and the trade has been immensely extended in recent times, when
the sponge has become an almost necessary adjunct of the toilet as well
as the stable, and in other cleansing operations.

Fishing usually commences towards the beginning of June on the coast of
Syria, and finishes at the end of October. But the months of July and
August are peculiarly favourable to the sponge harvest, if we may use
the term. Latakia furnishes about ten boats to the fishery, Batroun
twenty, Tripoli twenty-five to thirty, Kalki fifty, Simi about a hundred
and seventy to a hundred and eighty, and Kalminos more than two hundred.
The operations of one of these boats fishing for sponges on the Syrian
coast is represented in Plate II.

The boat's crew consists of four or five men, who scatter themselves
along the coast for two or three miles in search of sponges under the
cliffs and ledges of rock. Sponges of inferior quality are gathered in
shallow waters. The finer kinds are found only at a depth of from twelve
to twenty fathoms. The first are fished for with three-toothed harpoons,
by the aid of which they are torn from their native rock; but not
without deteriorating them more or less. The finer kinds of sponges, on
the other hand, are collected by divers aided by a knife; they are
carefully detached. Thus the price of a sponge brought up by diving is
much more considerable than that of a harpooned sponge. Among divers,
those of Kalminos and of Psara are particularly renowned. They will
descend to the depth of twenty-five fathoms, remain down a shorter time
than the Syrian divers, and yet bring up a more abundant harvest. The
fishing of the Archipelago furnishes few fine sponges to commerce, but a
great quantity of very common ones. The Syrian fisheries furnish many of
the finer kinds, which find a ready market in France; they are of medium
size. On the other hand, those which are furnished from the Barbary
coast are of great dimensions, of a very fine tissue, and much sought
for in England. On the Bahama banks, and in the Gulf of Mexico, the
sponges grow in water of small depth. The fishermen, Spanish, American,
and English, sink a long mast or perch into the water moored near the
boat, down which they drop upon the sponges; by this means they are
easily gathered.

[Illustration: Plate II.--Sponge Fishing on the Coast of Syria.]

In the Red Sea, the Arabs fish for sponges by diving, their produce
being either sold to the English at Aden or sent to Egypt.
Sponge-fishing is carried on at various other stations in the
Mediterranean, but without any intelligent direction, and in consequence
it is effected without any conservative foresight. At the same time,
however, the trade in this product goes on increasing. But it is only
a question of time when the trade shall cease; the demand which every
year clears the submarine fields of these zoophytes causes such
destruction that their reproduction will soon cease to be equal to the
demand.

In order to prevent this troublesome result, it is very desirable that
the several species of sponges should be naturalized on the French and
Algerian coast, and the cultivation and reproduction of the zoophyte
protected. For this purpose, the rocky coasts of the Mediterranean, from
Cape Cruz to Nice, and round the islands of Corsica and Hyères, in the
Algerian waters, and even some of the salt lakes of the departments near
the Mediterranean, might be utilized. The whole of the Italian littoral
would also be available under the new régime for this purpose.

M. Lamiral considered that the composition of the water of the
Mediterranean being thought the same on the coast of France, of Algeria,
and on the Syrian coast, that the difference of temperature between the
two latitudes--especially at the depth where the sponges flourish
most--would not interfere with the existence of these robust zoophytes,
and that their acclimatization on the coasts of France and Algeria would
be a certain success. He remarked, moreover, that the more the sponges
advanced towards the north, the finer and compacter their tissues
became; and he argued from this fact, that a considerable improvement in
the quality would result from the experiment.

The only difficulty, then, would consist in the transplanting sponges
from Syrian waters to the coasts of France and Algeria. A submarine
boat, such as M. Lamiral makes use of for operations conducted in deep
water, would, according to this naturalist, give every facility for
collecting sponges for the purpose. This boat can descend to great
depths, and its crew can dwell there a considerable time, for it is
continually fed with fresh air from above, which is conveyed by an
air-pump and tube into the interior of the boat, so that the men could
readily select such individuals as were suited for acclimatizing;
removing the blocks of rock along with them, either by placing them in
cases pierced with holes, or by towing them to their new abode.
Everything seems to promise that in the following year the zoophytes
would begin to multiply in their new country.

The larvæ might also be collected in the months of April and May, as
they separate from the parent sponge, and be transplanted to favourable
localities. At the end of three years, when these true submarine fields
would be ripe for harvesting, they could be put in train for methodical
collection by means of diving boats.

The toilet sponge is an article which produces a high price, often as
much as forty shillings the pound for very choice specimens, a price
which few commercial products attain, which prohibits its use, in short,
to all but the wealthy. It is, therefore, very desirable to carry out
the submarine enterprise of M. Lamiral. With the assistance of the
Acclimatization Society of Paris, some experiments have already been
made in this direction--so far without any satisfactory results, it is
true, but everything indicates that by perseverance we shall see the
enterprise crowned by the success it merits.

Such specimens as now reach our ports are chiefly distinguished by their
appearance, quality, and origin.

The fine soft Syrian sponge is distinguished by its lightness, its fine
flaxen colour, its form, which is that of a cup, its surface convex,
voluted, pierced with innumerable small orifices, the concave part of
which presents canals of much greater diameter, which are prolonged to
the exterior surface in such a manner that the summit is nearly always
pierced throughout in many places. This sponge is sometimes blanched by
the aid of caustic substances, acids, or alkalies; but this preparation
shortens its duration and changes its colour. This sponge is specially
employed for the toilet, and its price is high. Those which are
round-shaped, large, and soft, sometimes produce as much as five or six
pounds.

The _Fine Sponge of the Archipelago_ is scarcely distinguishable from
that of Syria, either before or after being cleansed; nevertheless, it
is weightier, its texture is not so fine, and the holes with which it is
pierced are at once larger and less in number. It is nearly of the same
country as the former, in fact, the fishing extending along the Syrian
coast as well as the littoral of Barbary and the Archipelago.

The _Fine Hard Sponge_, called Greek, is less sought for than either of
the preceding; it is useful for domestic and for certain industrial
purposes. Its mass is irregular, its colour fauve; it is hard and
compact, and pierced with small holes.

The _White Sponge of Syria_, called Venetian, is esteemed for its
lightness, the regularity of its form, and its solidity. In its rough
state it is brown in colour, of a fine texture, compact and firm.
Purified, it becomes flaxen and of a looser texture. The orifice of the
great channels which traverse it are edged with rough and bristly hairs.

[Illustration: (From Dr. Grant.)

Fig. 11. _Spongia oculata_, showing the orifices and currents outwards.
2. Anastomosing horny substance of _Spongia communis_. 3. Siliceous
spiculum of _S. papillaris_. 4. Of _S. cineria_. 5. _S. panicea_. 6.
Calcareous spiculum of _S. compressa_. 7. Transverse section of a canal
of _S. papillaris_, showing the structure of the ova passing along the
canal. 8. Ovum of _S. panicea_ seen laterally--the ciliæ anterior. 9.
The same seen on the end, with a circle produced by the ciliary action.
10. Young _Spongia papillaris_.]

The _Brown Barbary Sponge_, called the Marseillaise, when first taken
out of the water, presents itself as an elongated flattened body,
gelatinous, round in shape, and charged with blackish mud. It is then
hard, heavy, coarse, but compact, and of a reddish colour. By a simple
washing in water it becomes round, still remaining heavy and reddish. It
presents many gaps, the intervals of which are occupied by a sinuous and
tenacious network. It is valuable for domestic use, because of the
facility with which it absorbs water, and its great strength.

Other sorts of sponges are very abundant. The _Blonde Sponge_ of the
Archipelago, often confounded with the Venetian; the _Hard Barbary
Sponge_, called Gelina, which only comes by accident into France; the
_Salonica Sponge_ is of middling quality; finally, the _Bahama Sponge_,
from the Antilles, is wanting in flexibility and a little hard, and so
is sold at a low price, having few useful properties to recommend it.

Many species of _Spongia_ are described as inhabiting British seas, but
none of any commercial value. Regarding them as apolypiferous zoophytes,
Dr. Grant has pointed out certain principles of analysis on which they
may be grouped, according to the arrangement of the horny fibres, the
calcareous and siliceous spiculæ, and the distribution and formation of
their pores and orifices.


I. GROUPS OF WHICH THE CONSTITUENT STRUCTURE IS KNOWN.

_Spongia._--Mass soft, elastic, more or less irregular in shape, very
porous, traversed by many tortuous canals, which terminate at the
surface in distinct orifices. Substance of the skeleton cartilaginous,
fibres anastomosed in all directions, without any earthy
spicula.--Example, _S. communis_ (Fig. 11 [2]).

_Calcispongia_ (Blainville).--Mass rigid or slightly elastic, of
irregular form, porous, traversed by irregular canals, which terminate
on the surface in distinct orifices; skeleton cartilaginous, fibres
strengthened by calcareous spicula, often tri-radiate.--Example, _S.
compressa_ (Fig. 11 [6]).

_Halispongia_ (Blainville).--Mass more or less rigid or friable,
irregular, porous, traversed by tortuous irregular canals, which
terminate at the surface in distinct orifices; substance cartilaginous,
fibres strengthened by siliceous spicula, generally fusiform or
cylindrical.--Example, _S. papillaris_ (Grant) (Fig. 11 [3]).

_Spongilla_ (Lamarck).--Mass more or less rigid or friable, irregular,
porous, but not furnished with regular orifices or internal
canals.--Example, _S. fluviatalis_ (Linn.).


II. GROUPS DEPENDING ON CHARACTERS OF SURFACE OR GENERAL FIGURE.

_Geodia_ (Lamarck).--Fleshy mass, tuberous, irregular, hollow within,
externally incrusted by a porous envelope, which bears a series of
orifices in a small tubercular space.--Example, _G. gibberosa_
(Schmeiger).

_Coeloptychium_ (Goldfuss).--Mass fixed, pedicled, the upper part
expanded, agariciform, concave, and radiato-porose above, flat and
radiato-sulcate below; substance fibrous.--Example, _C. agarisidioideum_
(Goldfuss). Fossils from the chalk of Westphalia.

_Siphonia_ (Parkinson).--Mass polymorphous, free or fixed, ramose or
simple, concave or fistulous above, porous at the surface, and
penetrated by anastomosing canals, which terminate in sub-radiating
orifices within the cup.

_Myrmecium_ (Goldfuss).--Mass sub-globular, sessile, of a close fibrous
texture, forming ramified canals which radiate from the base to the
circumference. Summit with a central pit.

_Scyphia_ (Oken).--Mass cylindrical, simple, or branched, fistulous,
ending in a large rounded pit, and composed entirely of a reticulated
tissue.

_Eudea_ (Lamouroux).--Mass filiform, attenuated, sub-pedicellate at one
end, enlarged and rounded at the other, with a large terminal pit;
surface reticulated by irregular lacunæ, minutely porous.

_Halirrhoa_ (Lamouroux).--Mass turbinated, nearly regular, circular, or
lobate; surface porous; a large central pit on the upper face.

_Happalimus_ (Lamouroux).--Mass fungiform, pedicellate below, expanding
conically, with a central pit above; surface porous and irregularly
excavated.

_Cnemidium_ (Goldfuss).--Mass turbinate, sessile, composed of close
fibres and horizontal canals, diverging from the centre to the
circumference; a central pit on the upper surface, cariose in the
exterior and radiate at the margin.

_Ierea_ (Lamouroux).--Mass ovoid, sub-pedicellate, finely porous;
pierced on the upper part by many orifices, the terminations of the
internal tubes.

_Tethium_ (Lamarck).--Mass sub-globose, tuberose, composed of a cariose
firm substance, strengthened by abundance of siliciary spicula,
fasciculated, and diverging from the centre to the circumference.


RHIZOPODA.

Gervais and Van Beneden include under the name of _Rhizopods_, or
_foot-rooted_ animals (so called from ριξα,, _root_; πους,
ποδος, _footed animals_), those of the simplest organization, which
may be characterised by the absence of distinct digestive cavities, and
the presence of vibratile cilia, as well as by the soft parts of their
tissues. This tissue emits prolongations or filaments which admit of
easy extension, sometimes simple, sometimes branching. Occasionally we
see these branching filaments withdraw themselves towards the mass of
the body, disappear, and gradually melt into its substance in such a
manner that the individual seems to absorb and devour itself. If, in
exceptional cases, some of the superior animals, as the wolf, devour
each other, the rhizopods go much farther: they devour themselves, so
to speak!

The rhizopods are found both in fresh and salt water. They live, as
parasites, on the body of worms and other articulated animals. The class
is divided into many orders. We shall speak here only of three, namely,
the _Amoebæ_, _Foraminifera_, and _Noctiluca_.


AMOEBÆ.

In nearly all ancient animal and vegetable infusions, not quite
putrid--upon all oozy beds covering bodies which have remained for some
time in fresh or sea water--we find the singular beings which belong to
this order. They are the simplest organisms in creation, being reduced
to a mere drop of living matter. Their bodies are formed of a gelatinous
substance, without appreciable organization. The quantity of matter
which forms them is so infinitesimal, that it becomes incredibly
diaphanous, and so transparent that the eye, armed with the microscope,
traverses it in all directions, so that it is necessary to modify the
nature of the liquid in which it is held in suspension, and introduce
the phenomenon of refraction in order to observe them.

It would be difficult to say exactly what is the form these creatures
assume. They frequently have the appearance of small rounded masses,
like drops of water; but, whatever their form may be, it is always so
unstable, that it changes, so to speak, every moment, so that it is
found impossible to make a drawing from the model under the
microscope--the design must be finished by an appeal to memory. This
instability is the characteristic manifestation of life in the _Amoebæ_,
which are naked beings, without apparent organization; in fact, they
occupy the first step in the scale of creation.

The transparent immovable drop under consideration emits an expansion,
and a lobe of a vitreous appearance upon its circumference, which,
gliding like a drop of oil upon the object-glass of the microscope,
begins by fixing itself to it as a supporting point, afterwards slowly
attracting to itself the whole mass, and thus gradually increasing its
bulk under the observer's eye.

The _Amoebæ_, according to their dimensions and degree of development,
successively emit a greater or smaller number of lobes, none of which
are precisely alike, but, after having appeared for an instant, each
successively re-enters into the common mass, with which it becomes
completely incorporated. Variable in their respective forms, these lobes
present appearances quite different in the several genera. They are more
or less lengthy, more or less fringed, and often branching; sometimes
they are filiform, sprouting in all directions over the animal mass,
which rolls in the liquid like the husk of a small chestnut.

If we ask how these animals are nourished, in which no digestive
apparatus can be distinguished, the question is difficult to answer. It
is thought that they are nourished by simple absorption, and by
absorption only. In the interior of the gelatinous mass which
constitutes the animals, however, granules and microscopic portions of
vegetables are frequently discovered. "We can conceive," says Dujardin,
"how these objects have penetrated to the interior, if we remark, on the
one hand, that in creeping on the surface of the glass, to which they
adhere very exactly, the _Amœbæ_ can be made to receive, by pressure,
foreign substances into their own bodies, by means of the alternate
contraction and extension of the various parts natural to them, and, on
the other hand, that the gelatinous mass is susceptible of spontaneous
depressions--here and there near to or even at the surface of the
spherical cavities, which successively contract themselves and disappear
in connection with the strange body which they have absorbed."

The _Amoebæ_ are often observed to be tinted red or green; this arises
from the special colouring matter which has been absorbed into its mass.

The question arises, How do these creatures, so simple in their
organization, propagate their species?

We believe that they are chiefly multiplied by parting with a lobe,
which, in certain conditions, is enabled to live an independent
existence, and develop itself, thus forming a new individual. This is
what naturalists term generation by division--_fissiparism_ or
_fission_. The absence of a nutritive and reproductive apparatus in the
_Amoebæ_, and the want of stability in their forms, explain how nearly
impossible it is to characterise as species the numerous individuals
daily met with in infusions of organic matter in stagnant water. In
order to distinguish some of the groups, Dujardin bases his descriptions
upon their size and the general form into which they expand.

We shall be able to form some idea of the appearance of these beings,
rendered mysterious by their very simplicity, by throwing a glance upon
the two accompanying figures (Figs. 12 and 13), borrowed from the Atlas
of Dujardin's great work, "Les Zoophytes Infusoires," which we shall
have occasion to quote more than once.

We have said that the _Amœbæ_ change their form every few moments under
the eyes of the observer. Fig. 13 represents the changes of form through
which they pass, according to Dujardin, when examined under the
microscope.

[Illustration: Fig. 12. Amoebæ princeps (Ehrenberg), magnified 100
times.]

[Illustration: Fig. 13. Various forms of Amoebæ diffluens (Müller),
magnified 400 times.]

Dujardin points out very clearly the identity of structure between
organisms like _Amoebæ_ and such forms as _Difflugia_ and _Arcella_. All
these creatures are without trace of mouth or digestive cavity, and the
entire body is a single cell, or aggregation of cells, which receive
their nutriment by absorption; for, although the creatures have neither
mouth nor stomach, yet, according to Professor Kölliker, they take in
solid nutriment, and reject what is indigestible. When in its progress
through the water one of these minute organisms approaches one of the
equally minute Algæ, from which it draws nourishment, it seizes the
plant with its tentacular filaments, which it gradually encloses on all
sides; the filaments, to all appearance, becoming more or less shortened
in the process. In this way the captive is brought close to the surface
of the body; a cavity is thus formed, in which the prey is lodged, which
closes round it on all sides. In this situation it is gradually drawn
towards the centre, and passes at last entirely into the mass. The
engulfed morsel is gradually dissolved and digested.


FORAMINIFERA.

There is nothing small in Nature. The idea of littleness or greatness is
a human conception--a comparison which is suggested by the dimensions of
his own organs. Nature, on the other hand, compensates smallness by
numbers. The result produced by the bones of some large animals is also
accomplished by the accumulated spoils of millions of animalcules. The
history of the Foraminifera is a striking example of this great truth.

What, then, is a Foraminifer? It is a very small zoophyte, a shell
nearly invisible to the naked eye; for, in general, its dimensions
rarely exceed the two hundredth part of an inch; in short, it is
strictly microscopic. Examine under a microscope the sand of the ocean,
and it will be found that one-half of it consists of the débris of
shells, of various but well-defined forms, each habitually pierced with
a number of holes. To this they are indebted for their name
Foraminifera, from _foramen_, a hole. With these microscopic animalcules
Nature has worked wonders in geological times; nor have the wonders
ceased in our days.

Many beds of the terrestrial crust consist entirely of the remains of
Foraminifera. In the most remote ages in the history of our planet,
these zoophytes must have lived in innumerable swarms in the seas of the
period; they buried themselves in the bottoms of the seas, and their
shells, heaped up during many ages, have finished by forming hills of
great thickness and extent. We may say, to give an example, that during
the Carboniferous period, a single species of these zoophytes has
formed, in Russia alone, enormous beds of calcareous rock. Many beds of
cretaceous formation are, in great part, composed of Foraminifera, and
they exist in immense numbers in the white chalk which covers and forms
the vast mountains ranging from Champagne, in France, nearly to the
centre of England.

But it is to the Tertiary formation that these zoophytes have
contributed the most enormous deposits. The greater part of the Egyptian
pyramids is only an aggregation of _Nummulites_ inserted in the syenite.
A prodigious number of Foraminifera present themselves in the tertiary
deposits of the Gironde, of Italy, and of Austria. The chalk so abundant
in the basin of Paris is almost entirely composed of Foraminifera. The
remains of these creatures are so abundant in the Paris chalk, that M.
d'Orbigny found upwards of fifty-eight thousand in a small block,
scarcely exceeding a cubic inch of chalk, from the quarries of
Chantilly. This fact, according to this author, implies the existence of
three thousand millions of these zoophytes in the cubic mètre
(thirty-nine inches square and a small fraction) of rock! As the chalk
from these quarries has served to build Paris, as well as the towns and
villages of the neighbouring departments, it may be said that Paris, and
other great centres of population which surround it, are built with the
shells of these microscopic animals.

The sand of the littoral of all existing seas is so full of these minute
but elegant shells, that it is often half composed of them. Ehrenberg,
the celebrated German microscopist, was recently invited by the Prussian
government to assist in tracing the robbery of a special case of wine.
It had been repacked in littoral sand only found in an ancient sea-board
in Germany. The criminal was thus detected. M. d'Orbigny found in three
grammes (forty-six grains troy) of sand from the Antilles, four hundred
and forty thousand shells of Foraminifera. Bianchi found in thirty
grammes (four hundred and sixty-seven grains) from the Adriatic, six
thousand of these shells. If we calculate the proportion of these beings
contained in a cubic mètre alone of sea-sand, we reach a figure which
passes all conception. What would this be if we could extend the
calculation to the immensity of surface covered by the waves which
surround the globe?

M. d'Orbigny has satisfied himself, by microscopic examination of sands
from all parts of the globe, that it is the débris of Foraminifera which
form, in all existing seas, those enormous deposits which raise banks,
obstruct the navigation in gulfs and straits, and fill up ports, as may
be seen in the port of Alexandria. In common with the corals and
madrepores, the Foraminifera are the great agents in forming the isles
which surge up under our eyes from the bosom of the ocean in the warmer
regions of the globe. Thus shells, scarcely appreciable to the sight,
suffice by their accumulations to fill up seas, while performing a very
considerable part in the great operations of Nature, although it may not
be apparent to us.

Our exact knowledge of the Foraminifera is of very recent date. Great
numbers of minute particles, of regular and symmetrical form, were long
distinguished on the sands of the sea shore. These corpuscular atoms
early attracted the attention of observers. But with the discovery of
the microscope, these small elegant shells, which were among the
curiosities revealed by the instrument, assumed immense importance. We
have stated that these corpuscles are nothing but the shell or solid
framework of a crowd of marine animalculæ: we may then consider them as
living species analogous to the Ammonites and Nautilus of geological
times. Linnæus has placed them in this last genus, which would include,
according to that author, all the multilocular shells. In 1804, Lamarck
classed them among the molluscous cephalopods. But Alcide d'Orbigny, who
has devoted long years to study and observation, and may be considered
the great historian of the Foraminifera, makes it appear that this mode
of classification was inexact. Dujardin separated them altogether from
the class of mollusks, and showed that they ought to be consigned to an
inferior class of animals. These minute creatures, in short, are
deficient in the true appendages analogous to feet, which exist in the
higher mollusks. They simply possess filamentous expansions, very
variable in their form.

We have stated that the Foraminifera are of microscopic dimensions. With
some trifling exceptions, this is generally true; but there exist a
number of species which are visible to the naked eye. The Foraminifers
found in the nummulite formation of Tremsted, in Bavaria, between Munich
and Saltzberg, are still larger, being nearly double the size of the
nummulite of the Pyramids; in short, they are the giants of this tribe
of animals.

After these remarks, we may venture to give some idea of the structure
and classification of these beings, whose part in the work of creation
has, in former times, been so considerable.

The bodies of the Foraminifera are formed of a gelatinous substance,
sometimes entire and round, sometimes divided into segments, which can
be placed upon a line, simple or alternate, wound up into a spiral form
or rolled round its axis, like a ball. A testaceous envelope, modelled
upon the segments, follows the various modifications of form, and
protects the body in all its parts. From the extremity of the last
segment of one or many openings of the shell, or of the numerous pores,
issue certain long and slender filaments, more or less numerous, which
are divided and subdivided over their whole length, like the spreading
branches of a tree. They can attach themselves to external bodies with
force enough to determine the progression of the animal. Being formed of
transparent non-colouring matter, they may be said to be mere
expansions, which vary in form and length according to the conditions of
the ambient medium. The filaments have also very variable positions:
sometimes they form an unique and retractile band, issuing from a single
opening; sometimes they project themselves across from numerous little
pores in the shell, which covers the last segment of the animal. These
pores, or openings, give the name to the creatures under consideration.

In conclusion, the filaments, contractile and variable in their form,
which constitute the feet and arms of these little creatures, appear to
have something electric in them: it is stated that the Infusoria are at
once paralysed in their motions when brought in contact with the minute
arms of the Foraminifera. "It is probably by this means," says M.
Frédol, "that these creatures succeed in catching their prey. Is it not
worthy of remark that these beings, however small their size and slight
their form, are unpitying flesh-eaters? The smallest, the weakest, and
the most microscopic animal in existence thus becomes, by means of a
homœopathic dose of poison, a most formidable destroyer."

Another singular observation on these little filaments or arms we owe to
Dujardin. This naturalist observed that, when a _miliola_ attempted to
climb up the walls or sides of a vase, it could improvise, as it were,
on the instant, and at the expense of its own substance, a provisional
foot, which stretched itself out rapidly and performed all the functions
of a permanent member. The occasion served, this temporary foot seemed
once more to return to the common mass, and was absorbed into the body.
It would thus appear that with these minute creatures the presence of a
necessity gives the power to create an organ by the mere will of the
creature, while man, with all his genius, cannot manufacture a hair. To
the present day, however, we have not been able to discover any organ of
nutrition in the Foraminifera; they have no stomach, properly so called,
but Nature has gifted them with a peculiar tissue, at once gelatinous
and contractile, and essentially simulative, which probably serves the
same purpose.

We have already said that the shells of these minute zoophytes vary much
in form. They are generally many-chambered, each chamber communicating
by pores in the walls; the different gelatinous parts of the animalcules
are, in this manner, placed in continual communication with each other.
Alcide d'Orbigny, to whom we owe almost all that is known of the class,
has distributed them into six families, making the form of the shell the
basis of their arrangement. These six families include sixty genera, and
more than sixteen hundred species, the families being as follows:--

I. Monostega.--Animals consisting of a single segment. Shell of a single
chamber.

II. Stichostega.--Animal in segments, arranged in a single line. Shell
in chambers, superimposed linearly on a straight or curved axis.

III. Helicostega.--Animal in segments, spirally arranged. Chambers piled
or superimposed on one axis, forming a spiral erection. In Fig. 21 we
have a horizontal section of _Faujasina_, in which the spiral
convolutions are visible on the truncated half of the shell.

IV. Entomostega.--Animal composed of alternating segments forming a
spiral. Chambers superimposed on two alternating axes, also forming a
spiral.

V. Enallostega.--Animal formed of alternate segments. Non-spiral
chambers disposed alternately along two or three axes, also non-spiral.

VI. Agathistega.--Animal formed of segments wound round an axis.
Chambers formed round a common axis, each investing half the
circumference.

The simplest form of Foraminifera is illustrated by Fig. 14 (_Orbulina
universa_), which is a small spherical shell, having a lateral aperture,
the interior of which has been occupied by the living jelly, to which
the shell owes its existence. In the second order, the shell (Fig. 15),
_Dentalina communis_, advances beyond this simple type by a process of
linear budding, the first cell being spherical, with an opening through
which a second segment is formed, generally a little larger than the
first. This new growth is successively followed by others developed in
the same way, until the organism attains its maturity, when it exhibits
a series of cells arranged end on end, in a slightly curved line.

In the next group the gemmation takes a spiral bias, producing the
nautilus shape which misled the earlier naturalists. In some cases all
the convolutions are visible, as in _Operculina_ (Fig. 16). In others,
the external convolute conceals those previously formed, as in
_Nummulitis lenticularis_ (Fig. 17), _Cassidulina_ (Fig. 18),
_Textilaria_ (Fig. 19), and _Alveolina oblonga_, d'Orbigny (Fig. 25),
the latter forming part of the eocene formation in the quartz and
greystone rocks of the neighbourhood of Paris; one figure representing
the shell entire, and the other a vertical section, while the small
figure between represents it in its natural size.

[Illustration: Fig. 14. Orbulina universa.]

[Illustration: Fig. 15. Dentalina communis.]

[Illustration: Fig. 16. Operculina.]

[Illustration: Fig. 17. Nummulitis lenticularis.]

[Illustration: Fig. 18. Cassidulina.]

[Illustration: Fig. 19. Textilaria.]

[Illustration: Fig. 20. Spiroloculina.]

In the fourth group the shell is spiral, with the chamber equilateral,
with a larger and smaller side, the position being alternately reversed
as the segments are multiplied, as in _Cassidulina_ (Fig. 18). In the
succeeding group the new segments are arranged alternately on opposite
sides of the central line, as in _Textilaria_ (Fig. 19), thus forming
two alternating non-spiral parallel segments, each connected by a single
orifice.

The sixth family differ entirely in appearance and structure from the
other Foraminifera. They are more opaque than the other orders, having a
resemblance to white porcelain, which presents a rich amber-brown hue
when viewed by transmitted light. They are more or less oblong, each new
segment being nearly equal to the entire length of the shell, so that
the terminal orifice presents itself alternately at its opposite
extremities, sometimes in one uniform plane, as in _Spiroloculina_ (Fig.
20), and _Faujasina_ (Fig. 21). At other times each new segment, instead
of being exactly opposite each other, is a little on one side.

[Illustration: Fig. 21. Faujasina.]

Professor Williamson has shown that the shell enclosing each new segment
is at first very thin; but as additional calcareous chambers are formed,
each addition not only encases the new gemmation of the soft animal, but
extends over all the exterior of the previously formed shell. The exact
manner in which this is accomplished is doubtful; but the Professor
thinks it probable that the soft animal has the power of diffusing its
substance over the shell, and thus depositing upon its surface
additional layers of calcareous matter.

The fossil Foraminifera are chiefly distinguished from recent and
existing species by the size of the former. While the living forms range
from one-fourth to the one-hundredth part of an inch, the tertiary
strata abound in examples of _Nummulites_ varying from the eighth of an
inch to the size of half-a-crown. The engraving is a drawing from
Nature, by MM. d'Archaic and Haime, of a piece of nummulitic rock, of
Nousse, in the Landes, in which a great variety of sizes and forms are
exhibited.

The Nummulina belong to the third family, or Helicostega, in which the
outer convolutions completely embrace the earlier-formed ones. Hence it
is only by making microscopic sections, or thin slices, that their
structure can be fully seen. When such a section is carried horizontally
through the centre of the shell, the segments present a spiral
arrangement, which, like the convolutions, are remarkable for their
small size, and consequent great number.

[Illustration: Fig. 22. Nummulites Rouaulti (d'Archaic and J. Haime).]

[Illustration: Fig. 23. Siderolites calcitrapoides (Lamarck). Natural
size and magnified.]

With respect to the distribution of the Foraminifera according to
geological periods, we may briefly state that they have been found in
every formation from the Silurian to the Tertiary. The species, at first
very simple in their forms, begin to appear in increasing numbers in the
carboniferous formations. They become more numerous, and, at the same
time, more complex in their forms, in the Cretaceous period; they are
still more diversified, and appear to have multiplied much more rapidly
in the Tertiary period, where they attain the maximum of their numerical
development. In the celebrated quarries of St. Peter, at Maestrecht, the
_Siderolites calcitrapoides_ of Lamarck are found in the upper chalk
(Fig. 23). In the calcareous formation of Chaussy, in the Seine and Oise
district, and other parts of the Paris basin, the _Fabularia
discolithes_ (Fig. 24) of Defrance is found. Finally, the _Dactylopora
cylindracea_ of Lamarck (Fig. 26) is found in the eocene formation of
Valmondois and in the chalk of Grignon. At first, this little creature
was thought to be a polype; but d'Orbigny, in his "Prodrome de
Paleontologie," has placed it among the Foraminifera, thinking that it
appeared to occupy a place between the two classes.

[Illustration: Fig. 24. Fabularia discolithes (Defrance). Natural size
and magnified.]

[Illustration: Fig. 25. Alveolina oblonga (d'Orbigny). Natural size and
magnified.]

[Illustration: Fig. 26. Dactylopora cylindracea (Lamarck). Natural size
and magnified.]

The existing Foraminifera are by no means equally distributed in every
ocean. Some genera belong to warm countries, others to temperate and
cold climates. They are much more numerous, however, and much more
varied in their forms, in warm than in cold climates, and, we may add,
larger also, for Sir E. Belcher brought a recent species from Borneo
which measured two inches in diameter.

       *       *       *       *       *

Before passing on to the study of the Infusoria, a few words may be
offered on the _Noctiluca_, a genus of animals usually referred to the
class ACALEPHÆ. One species only of this genus has been described, which
occurs occasionally on the English coast in prodigious numbers. It is a
small creature, scarcely the hundredth part of an inch in diameter,
according to Mr. Huxley (Fig. 27, _Noctiluca miliaris_). It was
discovered by M. Surriray, in 1810, who describes it as a spherical
gelatinous mass, scarcely bigger than a pin's head, with a long filiform
tentacular appendage, a mouth, an oesophagus, one or many stomachs, and
branching ovaries--thus exhibiting a certain complexity of organization.
De Blainville took the same view, and placed it among the _Diphydæ_. Van
Beneden and Doyère, on the other hand, deny its relation to the
_Acalephæ_, conceiving its organization to be much more simple: they
place it with the _Rhizopoda_. Quatrefages adopts the same view, denying
the existence of a true mouth or intestinal canal: he considers the
so-called stomachs as simple "vacuales," similar to those observed in
the Rhizopoda and Infusoria. Mr. Huxley, describing it in the "Journal
of Microscopical Science" (vol. iii.), says it has nearly the form of a
peach, a filiform tentacle, equal in length to the diameter of the body,
occupying the place where the stalk of the peach might be, which depends
from it, and exhibits slow wavy motions when the creature is in full
activity. "I have even seen a _noctiluca_," he adds, "appear to push
against obstacles with this tentacle."

[Illustration: Fig. 27. Noctiluca miliaris. Magnified.]

"The body," he continues, "is composed of a structureless and somewhat
dense external membrane, which is continued on to the tentacle. Beneath
this is a layer of granules, or rather of gelatinous membrane, through
whose substance minute granules are scattered without any very definite
arrangement; from hence arises a network of very delicate fibrils, whose
meshes are not more than one three-hundredth part of an inch in
diameter, which gradually pass internally--the reticulation becoming
more and more open--into coarser fibres, taking a convergent direction
towards the stomach and nucleus. All these fibres and fibrils are
covered with minute granules, which are usually larger towards the
centre."

Mr. Huxley is inclined to think, from all he has observed, that the
animal has a definite alimentary cavity, and that this cavity has an
excretory aperture distinct from the mouth.

Surriray discovered the _noctiluca_ while investigating the cause of
phosphorescence of sea water at Havre, where it was abundant in the
basins; sometimes in such abundance as to form a crust on the surface of
the water of considerable thickness. "This singular little creature,"
says M. Frédol, "offers here and there in its interior certain granules,
probably germs, and also luminous points, which appear and disappear
with great rapidity--the least agitation determining their lustre." The
_noctiluca_ are so abundant in the Mediterranean and in some parts of
the channel, that in a cubic foot of sea water, which has been rendered
phosphorescent by their presence, it is calculated that there exist
about twenty-five thousand.


INFUSORIA.

With the Infusoria we return to the domain of the infinitely little. Of
this very interesting group a large proportion are marine, and numerous
varieties of them are found in British seas. In their minuteness and
variety they almost baffle the attempts of naturalists to classify them.

The waters, both fresh and salt, are inhabited by legions of active,
ever-moving beings, of dimensions so small as to be inappreciable to the
naked eye; these minute creatures are disseminated by millions and
thousands of millions in the great deep, and all knowledge of them would
have escaped us, as they escaped the knowledge of the ancients, but for
the discovery of the microscope, the sixth sense of man, as it has been
happily expressed by the historian and poet Michelet. Another writer of
equally poetical mind, M. Frédol, tells us that "the infusorial
animalcules are so small that a drop of water may contain them in many
millions. They exist in all waters, the fresh as well as the salt, the
cold as well as the hot. The great rivers are continually discharging
them in vast quantities into the sea."

The Ganges transports them in the course of one year in masses equal to
six or eight times the size of the great pyramid of Egypt. Among these
animalcules, according to Ehrenberg, we may reckon seventy-one different
species.

The water collected in vases between the Philippine and the Marianne
Isles at the depth of twenty-two thousand feet (making some allowance
for erroneous soundings), have yielded a hundred and sixteen species.
Near the Poles, where beings of higher organization could not exist, the
Infusoria are still met with in myriads; those which were observed in
the Antarctic Seas, during the voyages of Captain Sir James Ross, offer
a richness of organization, often accompanied by elegance of form, quite
unknown in more northern regions. In the residuum of the blocks of ice
floating about in latitude seventy-eight degrees ten minutes, nearly
fifty different species were found. Many of them had ovaries, according
to Ehrenberg, still green, which proved that they had struggled
successfully with the rigours of the climate in searching for food.

At a depth in the sea which exceeds the height of the loftiest mountain,
Humboldt asserts that each bed of water is animated by an innumerable
phalanx of inhabitants imperceptible to the human eye. These microscopic
creatures are, in short, the smallest and the most numerous creations in
Nature. They constitute with human beings one of the wheels of that very
complicated machine, the globe. They are in the rank and at the station
willed for them, as determined in the great First Thought. Suppress
these microscopic beings, and the world would be incomplete. It was
said, and wisely said, long, long ago, "there is nothing so small to the
view but that it may become great by reflection."

The Infusoria, in short, abound everywhere. We find their remains on the
loftiest mountain ridges, and in the profoundest depths of the sea. They
increase and multiply alike under the Equator, and towards the polar
regions. The seas, rivers, ponds--the flower vase which rests upon the
casement--even our tissues, and the fluids of our bodies--all contain
infusorial animalcules. Whole beds of strata, often many feet thick, and
covering a surface of considerable extent, are almost exclusively formed
of their accumulated débris. It is to the Infusoria that the mud of the
Nile and other fluviatile and lacustrine deposits owe their prodigious
fertility. To them also is due the red or green layer of colouring
matter found in ponds and tanks at certain seasons. When exposed to
great solar heat, in order to extract the salt, as it is in the vast
artificial basins hollowed out for the purpose in the salt marshes near
the sea-shore in the south of France, the salt water, when it reaches a
certain degree of concentration, acquires a fine rose colour, which is
due to the presence of innumerable masses of small Infusoria having a
reddish shell. Finally, let us add that the solid débris of certain
fossil Infusoria, of surprising minuteness, have formed the stone so
much used by workers in metal, which is known as _tripoli_.

The study of these creatures is intensely interesting to the naturalist,
the philosopher, the physician, and the general reader. They have had a
great part assigned to them in Nature, as is evident in the formation of
certain beds of rock of immense extent, in which the geologist traces
their action.

Our earliest knowledge of the Infusoria is traceable to the seventeenth
century; to the celebrated naturalist, Leuwenhoek, we are indebted for
their discovery. On the 24th of April, 1676, this observer saw for the
first time some infusorial animalcules. Fifty years later, Baker and
Trembley studied them anew. In 1752, Hill essayed the first attempt at
their classification. In 1764, Wiesberg gave them the name of Infusoria,
because he found them in such great abundance in animal and vegetable
_infusions_. Müller published a special book upon them.

From that time the Infusoria have been considered as forming a special
group among the radiate animals; afterwards, in the pages of Baer and of
De Blainville, we see in these creatures, so imperfect in appearance,
only the indeterminate prototype of other classes. But ideas changed
altogether respecting them when microscopes of great power, and armed
with achromatic lens, were employed in their study. Thanks to the
labours of Ehrenberg and Dujardin, we have arrived at a better
comprehension of the organization of these infinitely small beings.
Naturalists have established, with more exactness, the limits of the
zoological group to which they belong.

Some stagnant waters are so filled with Infusoria that it is only
necessary to dip at random into the liquid medium to procure them in
abundance. In other waters they form a bed, occupying the whole basin.
In general, it is necessary to search for them where the water is calm,
and occupied by vegetation of some kind, such as the _confervæ_, or
_lemna_, &c., in the marshes, and _ceramium_ if in the sea. Certain
Infusoria live not only in water, but also in places habitually moist,
as among tufts of mosses; in beds of _oscillaria_, on moist soil, or on
air-damp walls. Others live as parasites on the exterior or in the
interior of animals, such as _hydra_, _lombrics_, and _naïads_.
Quantities of them are found in the liquid excrements and other
products of certain organisms, and they have been noted even in women's
milk.

But, as their name indicates, it is in aqueous infusions, vegetable or
animal, that these animalcules abound. Armed with a microscope, the
reader may, with very little trouble, afford himself the pleasure of
studying these animals. It is only necessary to place some organic
débris--the white of an egg, or some grass, for example--in a vase with
a large mouth, filled with water, and expose it to the light and air.
Certain reagents, as phosphate of soda, the phosphates, nitrates, or
oxalates of ammonia, or carbonate of soda added to these infusions, will
singularly favour the development of Infusoria.

There are also some accidental infusions which seem to furnish these
microscopic beings in great abundance. Water which stagnates in garden
soil or in vegetable mould, in the watering-cart or in flower vases, is
filled with myriads of these beings.

       *       *       *       *       *

So much for the medium in which they live, move, and have their being.
Let us pass on to their organization. We have already dwelt on their
extreme minuteness; their mean size is a fifth of a line or the sixtieth
part of an inch; the largest species scarcely reveal themselves to the
naked eye. They are generally colourless; some of them are,
nevertheless, green, blue, red, brown, and even blackish. Seen on the
object-glass of the microscope, they appear to be gelatinous,
transparent, and naked, or invested with an envelope more or less
resistant, which we shall designate after Dujardin by the term
_Sarcoda_, a substance which is homogeneous, diaphanous, elastic,
contractile, and, above all, destitute of every kind of organization.
They are usually ovoid or globular. Those most frequently met with, and
which attract the most attention from observers, are furnished with
_vibratile cilia_, which cover the whole body, acting as paddles. These
organs are evidently intended to propel the animal from one place to
another. At other times they appear to be employed in conveying food to
the mouth, if we may use the expression. Some Infusoria are without
these cilia, having only one or many very slender filaments, the
undulating movement of which suffices to determine their progression
through the liquid which surrounds them.

Authors who have written on the Infusoria have sometimes, like
Leuwenhoek, Ehrenberg, and Pouchet, attributed to them a very complex
structure. Others, like Müller, Cuvier, and Lamarck, have considered
them to be gifted with an organization extremely simple. We shall
probably find that the truth lies between these two extremes.

In the superior Infusoria, besides the granules, the interior globules,
vesicles full of liquid, vibratile cils, and a tegumentary system, more
or less complex, we find the substance which is called _Sarcoda_.

The digestive apparatus of the Infusoria has been the subject of
numerous observations, and has been provocative of very animated
discussions. In the inferior order of the class, which comprehends the
very smallest animalcules, it has not been found possible to observe the
organization of the digestive apparatus in a satisfactory manner. Some
writers think they have no mouth, what has been taken for that organ
being only hollow dimples on the surface of the body; others recognize
the existence of a buccal orifice, sometimes furnished with a solid
armature. As to the arrangements of the interior cavities in which
digestion takes place, we know nothing certain.

The digestive apparatus is better understood in the superior Infusoria,
called _ciliate_, namely, those provided with _vibratile cils_. These
cils seem to determine the currents of the liquid, leading the nutritive
corpuscles suspended in the water towards the entrance of the digestive
apparatus. They form, in some sort, the prehensile organs which seize
the aliment. The cils are, at the same time, the organs intended to
facilitate respiration; in short, these little whips playing upon the
water unceasingly round the Infusoria, is just the action required for
the absorption of the oxygen contained in the water. These cils, then,
serve at once for the propulsion of the animal, for its nutrition, and
for its respiration, presenting a remarkable example of cumulative
functions in physiology.

The corpuscles of nutritive substances directed towards the buccal
orifice by the vibratile cils soon disappear in the interior of the
animal. Availing himself of this fact and the transparency of the
animal, Herr Gleichen, a German physiologist of the last century,
conceived the happy idea of colouring the water which contained these
animalcules with a finely-powdered carmine; he traced the colouring
matter in the bodies of some of them. But it was reserved for Ehrenberg
to avail himself of the same artifice in order to study the internal
structure and mode of absorbing nutritive matter in these minute
creatures. This physiologist fed many groups of Infusoria, some of them
with water coloured with carmine, others with indigo and other
colouring matters. He saw, besides, some coloured globules, nearly
uniform in size, in different individuals of the same species. From this
he arrived at the conclusion that the colouring matter was deposited in
many of the surrounding dimples. Ehrenberg thought that each of these
dimples was a stomach, and that the introduction of the food into the
interior of these reservoirs, as well as the evacuations, were produced
by means of an intestine around which these stomachs are arranged. In
some cases he even thought he could distinguish the outlines of this
intestinal canal, and its connection with numbers of ampula or bladders.
Generalizing the conclusions drawn from his observations, in short, we
find that his class, Infusoria, embraced two very different forms of
animal life, which he divided into _Infusoria_, _Polygastrica_, and
_Rotifera_, the latter division including those known as Wheel
animalcules; the _Polygastrica_ being so called from his idea that the
typical forms possessed a number of stomachs. In some, Ehrenberg counted
four stomachs, an organization which brings these microscopic beings
into a strange kind of comparison with the ox and the goat. In others he
counted two stomachs.

Other observers were not slow in raising objections to these views.
Dujardin, especially, was much opposed to the batch of stomachs
attributed to these creatures by the German physiologist. He attempted
to establish the fact that the coloured globules which appeared in the
bodies of the Infusoria, while subjected to a regimen of carmine and
indigo, are not confined by a membrane; that is to say, they are not
contained in intestinal sacs. According to Milne Edwards, "they are a
species of basins, constituted," he says, "by the alimentary matter with
which each is gorged, united into a rounded pasty mass, where it could
no longer be dispersed, but would continue to advance, still preserving
its form. We have, in short, seen these spherules changing their places,
and passing one another in their progress from the mouth to the
intestinal canal. That they could not do this is evident, if many
stomachs were attached to the intestinal canal!"

This opinion, due to the patient and precise studies of Dujardin, has
been adopted by most naturalists of eminence. Besides, this learned
microscopist does not admit that there was in the sarcodic mass of
Infusoria any pre-existent cavity destined to receive the food. In a
word, he does not recognise any stomach whatever. This view of the
extreme simplicity of structure in the Infusoria has, however, met with
much opposition. To accord them neither four nor two stomachs, it is not
necessary to deprive them of the organ altogether. Meyen represents them
as having one great hollow stomach occupied by a pulpy matter, into
which the alimentary masses are successively absorbed. "All recent
observations," says Milne Edwards, "tend to establish the fact that the
digestive apparatus of the ciliate Infusoria consists of--first, a
mouth; second, of a pharyngeal canal, in which the food often assumes
the form of a _bolus_; third, of one great stomach with distinct walls,
and more or less distant from the common tegumentary membrane; fourth,
of an excretory orifice."

This mouth presents sensible differences both as to its position and
conformation, often occupying the bottom of a hollow, the edges of which
are furnished with well-developed _cilia_, the action of which attracts
the aliment; in short, the mouth is a sort of decoy at the bottom of a
simple pit, being at once contractile and prehensile, the interior part
being sometimes capable, according to Milne Edwards, of being turned
inside out in the form of a trumpet, while in a great many species it is
provided with a peculiar armature, consisting of a band of rigid
bristles disposed in the form of a bow-net, and susceptible of
dilatation and contraction, according to the wants of the animal. The
oesophagus, which is connected by means of the canal with the mouth, has
generally an oblique direction backwards, often terminating in a great
undivided stomach.

The reproduction of the Infusoria exhibits some very surprising
phenomena, while it offers another proof of the wonderful means Nature
employs for perpetuating the races of animals. They can be reproduced by
three different processes: 1. By _gemmation_, or budding, somewhat after
the manner of plants. 2. By sexual reproduction; for in these little
creatures it has recently been discovered that sexual differences exist.
3. By the spontaneous division of the animal into two individuals--a
process known to zoologists as _fissiparism_ or _fission_.

Among these three processes, that which appears best understood is the
last. The singular phenomenon of spontaneous division may be witnessed
by any one having patience to examine the creature long enough, isolated
from its innumerable companions, under the microscope. The oblong body
of the animal will soon be observed to contract at the middle, the
compression becoming more and more marked. The lower segment soon
begins to show a few vibratile cils, thus indicating the place which
will soon be a new mouth; the organ soon becomes more and more distinct,
and now the Infusoria literally cuts itself into two parts. We see, at
first, the fragment of glutinous substance fluttering on the edge of the
plate; the two halves then separate from each other very quickly, each
moiety having finally a perfect resemblance to the primitive animal.
This process is represented in Fig. 28, A and B being the adult, C the
same in course of separation, D after its completion. Assuredly this is
one of the most remarkable phenomena which the study of living beings
can present. "By this mode of propagation," says Dujardin, "an infusoria
is the half of the one which preceded it, the fourth of the parent of
that, the eighth of its grand-parent, and so on, if we can apply the
terms father or mother to animals which must see in its two halves the
grandfather himself by a new division again living in his four parts. We
might imagine such an infusoria to be an aliquot part of one like it,
which had lived years, and even ages before, and which by continued
subdivision into pairs might continue to live for ever by its successive
development."

[Illustration: Fig. 28. Propagation of an Infusoria by spontaneous
division.]

This mode of generation, however, enables us to comprehend the
miraculous fecundity of these beings. The process defies calculation, if
we wished to be precise. We may, however, arrive at a proximate estimate
of the number which may be derived from a single individual by this
process of fission. It has been found that at the end of a month two
_Stylonichiæ_ had a progeny of more than one million and forty-eight
thousand individuals, and that in a lapse of forty-two days a single
_Paramecium_ had produced more than one million three hundred and
sixty-four thousand forms like itself.

Life is spread over Nature in such abundance that the smallest infusoria
has its parasite a little smaller; these in their turn serving as "a
dwelling and pasture ground," to use Humboldt's words, for still smaller
animalcules, as represented in Fig. 29--_a_ being parasites in various
stages; _b_, the larger animalcule on which they have established
themselves.

[Illustration: Fig. 29. Paramecium aurelia and its Parasites.]

The prodigious number to which the calculation would reach, if we were
to add the other modes of propagation, viz., by germs and by budding, we
dare not mention: it would only be necessary to place a single germ in a
favourable condition for its development, in order to produce myriads of
these microscopic animalcules in a very few days.

We have seen three modes of reproduction in the Infusoria; it is
possible that a fourth mode exists, to which its partisans give the name
of _spontaneous generation_. According to their views, an infusoria can
be produced without egg-germ or pre-existent parent. It would be
sufficient to expose organic matter, animal or vegetable, to the action
of the air and water at a suitable temperature, in order to see this
matter organize itself, and form itself into living infusorial animals.

Such is the general enumeration of the question of spontaneous or
_heterogeneous_ generation, on which so much has been written in the
last ten years. The great expounders of the doctrine have been the two
French naturalists, MM. Pouchet and Joly. Their views have, however,
made little progress; they have, on the contrary, met with vigorous
opposition from the generality of French naturalists, and from most of
the members of the Académie des Sciences of Paris, who have raised their
voices against a doctrine which is contrary to the ordinary course of
nature. In short, the direct observations made upon the theory of
"primitive generation" are as yet wanting in necessary exactness; those
observers who profess to have witnessed the sudden origin of the
minutest of the infusoria from elementary substances have in all
probability overlooked the organic structure of these elementary bodies.
The wonderful changes of form undergone by many infusoria have their
limits, and the laws governing them have still to be defined. With the
poet we may say:

    "Grammatici certant et adhuc sub judice lis est."

Many of the Infusoria are subject to metamorphoses, and it has already
been ascertained that certain species which have been considered as
distinct are only transition forms of the same species depending on age.

We know that it is common for insects to enclose themselves in
protecting envelopes, and to remain for whole months shut up in this
their retreat, to all appearance dead. Similar facts have been observed
in the Infusoria. We have even seen some of these beings surrounding
strange bodies as if in a mass of jelly, forming a sort of living
envelope around them.

The average duration of life with them is only a few hours; but certain
species present, in relation to the duration of life, phenomena which
are only imperfectly known, but which never fail to excite the surprise
and admiration of the naturalist. By drying certain infusoria with care,
it is possible to suspend and indefinitely prolong its life. Thus dried,
and covered with a powder, which shelters it from every breath of wind,
it may be carried to any given distance, through any indefinite period
of time--abandoned on some ledge of rock, on a housetop, in the cleft
of a wall, or under the capital of a column; but let a drop of water
approach it, and the dormant being awakes immediately--the microscopic
Lazarus springs again into existence: feeds and multiplies as before:
and its life, suspended possibly for years, resumes its interrupted
course!

Into what a world of reflection does not a revelation of this mysterious
property of a living creature plunge us!

The physiologist Müller has noted another peculiarity in infusorial
life. These animalcules can lose a part of their bodies without being
destroyed; the dead part disappears, and the individual, diminished by
one-half, or reduced to a fourth of its former size, continues to live
as if nothing had happened. Müller has observed a kalpode (_Kolpoda
meleagris_) thus melt before his eyes until scarcely a sixteenth part of
its body remained. After its loss, this sixteenth part of an animal
continued to swim about without troubling itself as to its diminished
proportions. "The infusoria," says Frédol, in "La Monde de la Mer,"
"present yet another kind of decomposition. If we approach the drop of
water in which it swims with the barb of a feather dipped in ammonia,
the animalcule is arrested in its movement, but its cils continue to
move rapidly. All at once, upon some point of its circumference, a notch
is formed, which increases bit by bit until the whole animal is
dissolved. If a drop of pure water is added, the decomposition is
suddenly stopped, and what remains of the animalcule recommences its
swimming movements." (Dujardin.)

We may divide the Infusoria into two orders--the _Ciliate Infusoria_,
namely, those provided with vibratile cilia, and the _Flagelliferous
Infusoria_, those, namely, which have arms or branches. The greater part
of Infusoria belong to the first order, which comprehends many families;
our space limits us to the mention here of a few typical forms only in
each group, selecting those which appear the most interesting, from
their size, structure, rarity, or abundance.


FLAGELLIFEROUS INFUSORIA.

The family of _Vibrionidæ_, so named from their darting or quivering
motion, includes the eel-like microscopic animalcules which occur in
stale paste, vinegar, &c., with some others, which are parasitic on
living vegetables, such as _Vibrio tritici_, which infest the grains of
wheat, producing the destructive disease called corn-cockle or purples.
They are filiform animals, extremely slender, without appreciable
organization, internal stomach, or apparent organs of locomotion. They
are the first animalcules which show themselves in any infusion of
organic matter. By using microscopes of the highest magnifying power,
traces of very thin, short lines can be perceived, either straight or
sinuous, the thickest of them not exceeding the thousandth part of the
fraction of an inch. They are contractile, and propagated by spontaneous
division, or _fission_. Among them some resemble right lines, more or
less distinctly articulated, and endowed with a very slow movement;
these are _Bacteridæ_. Others are flexuous and undulating, and more or
less lively; these are true _Vibrions_. Others have the body fashioned
in the form of a corkscrew, turning unceasingly upon themselves with
great rapidity; these are the _Spirillidæ_, having an oblong fusiform or
filiform body, which undulates or turns spirally upon itself.

[Illustration: Fig. 30. Bacterium, termo (Müller), magnified 600 times.

The same, magnified 1600 times.]

The _Bacterium termo_ (Fig. 30) is the smallest of the Infusoria. It is
found, at the end of a short time, in all vegetable or animal infusions
exposed to the air. It shows itself in infinite numbers, forming swarms
of animalcules, which disappear as other species multiply in the liquid,
to which animals it serves for nourishment. When the infusion becomes
too foetid for these new species to live in it, in consequence of
fermentation or putrefaction, the _Bacterium termo_ reappears. This
species was one of the first observed; Leuwenhoek found it in the white
matter in the teeth and gums, which is called teeth tartar. It is also
found in the fluids of various animals which have been affected by
disease.

[Illustration: Fig. 31. Vibrion baguette (Müller), magnified 300 times.]

The _Wand-like Vibrion_ (Fig. 31) has the body transparent, filiform,
with long articulations, often appearing as if broken at each
connection. It moves very slowly in the water. Leuwenhoek observed this
second species joined to the first in the teeth tartar, and also in a
great number of organic infusions. "There is no microscopic object,"
says Dujardin, "which excites the admiration of the observer more
vividly than the twisting spirillum" (Fig. 32). He is struck with
surprise when he first contemplates this little creature, which, under
the greatest magnifying power, only presents the appearance of a thin
black line, fashioned like a corkscrew, which every instant turns upon
itself with marvellous velocity, such as the eye can scarcely follow, or
the mind divine the cause which produces this startling phenomenon.

[Illustration: Fig. 32. Spirillum tournoyant (Ehr.), magnified 300
times.]

The _Monads_ are other infusorial animalcules which make an early
appearance in vegetable infusions. They constitute a family that are
destitute of any covering. The substance of their bodies can swallow
itself, or draw itself out more or less; many of the whip-like filaments
serve as organs of locomotion. They are sometimes provided with lateral
appendages disposed as a kind of tail. Their organization is extremely
simple; their whip-like filaments are so fine as to be scarcely
perceptible, their length being sometimes double and even quadruple the
length of the animal itself.

The _Lentille Monad_ (Fig. 33) is a species which is frequently met with
in vegetable and animal infusions. The older microscopists had it
indicated under the form of a globule, moving in a slow and vacillating
manner. The globule is formed of a homogeneous transparent substance,
swollen into tubercles on its surface, and throws out obliquely a
whip-like filament, three, four, or even five times the length of the
body of the Monad.

The _Cercomonad_ of Davaine was discovered by this gentleman in the
still warm ejections of cholera patients. Its body is pyriform, having,
in front, a vibratile filament, very long, very flexible, and easily
agitated. Behind the body there is a thicker straight filament attaching
itself sometimes to neighbouring corpuscles, round which, in this case,
the _Cercomonad_ oscillates like the ball of a pendulum round its stem.

[Illustration: Fig. 33. Monade lentille (Dujardin), magnified 1000
times.]

The _Volvocineæ_ are inhabitants of fresh limpid water full of confervæ
and other aquatic plants. The _Volvocineæ_ are, according to Dujardin,
animalcules of a green or yellowish brown colour, regularly disseminated
in the thickness and near the surface of a gelatinous and transparent
globe, which would become hollow and be filled with water in its perfect
state. In this state, from five to eight smaller globules, with the same
organization, appear destined to undergo the same changes when they are
released by the rupture of the globule. These animalcules are each
furnished with one or two flagelliform filaments, which, by their
agitation, determine the movement by rotation of the mass.

A very remarkable phenomenon is recorded in the Transactions of the
Microscopic Society, namely, the conversion of the contents of an
ordinary vegetable cell into a free moving mass of Protoplasm, bearing a
strong resemblance to the animal _Amoebæ_ (Fig. 20). This, it is
affirmed by Dr. Hicks, takes place in Volvox, under circumstances which
suggest a vegetable transformation. But Dr. Carpenter does not consider
that this involves any real confusion in the boundaries of Animal and
Vegetable Life.

[Illustration: Figs. 34 and 35. Volvox globator (Müller), magnified 700
times.]

The Revolving Volvox, _V. globator_ (Figs. 34 and 35), is found in great
abundance, during summer, in tanks and ponds of stagnant water. It
consists of green or brownish-yellow globules about the eighth part of
an inch, formed of animalcules scattered round a gelatinous and
diaphanous spherical membrane, each furnished with a flagelliform
filament and with a reddish interior point, which Ehrenberg took for an
eye. Leuwenhoek first observed this Volvox in marshy waters. This
eminent naturalist has left a very interesting account of his
observations on these microscopic inhabitants of the waters, displaying
an amount of patience and address which cannot be too much admired; his
observations were made with a simple lens, which he constructed himself.
In one hand he held his instrument, which was very coarse if we compare
it to the more perfect and infinitely more powerful instruments now in
use; whilst, in the other hand, he carried to his eye the glass tube
full of water which contained the object under observation. "The
microscopes of Leuwenhoek," says Dujardin, "were the very smallest
bi-convex lenses, mounted in a silver frame. He made a collection of
twenty-six, which he bequeathed to the Royal Society of London. These
instruments, subject to all the inconveniences of a maximum of
spherical aberration and a total want of stability, were only fit for
use in the hands of Leuwenhoek himself, who had acquired, in his labour
of twenty years, habits of observation which compensated, in great part,
for the want of perfection in his instruments."

The _Eugleniæ_ are infusoria usually coloured green or red. Their form
is very variable. They are oblong or fusiform in shape, swelling at the
middle during action, and contracted or bowl-shaped in repose, or after
death. They are furnished with the usual whip-shaped filament, which
issues from an opening in front, and from one or many reddish points
irregularly placed anteriorly.

_Euglenia viridis_ (Fig. 36) is the most common species, and, perhaps,
the most widely diffused of all the Infusoria. It is this animalcule
which habitually covers stagnant pools with its floating surface of
green, and which forms, on the surface of marshy waters, the shining
pellicle so strongly coloured, which, collected upon paper, so long
preserves its brilliant tint.

[Illustration: Fig. 86. Euglenia viridis (Ehr.), magnified 350 times.]

The _Euglenia sanguinea_, at first green, becomes subsequently of a
blood colour. It has often been met with by microscopists. Ehrenberg,
who first described it, attributes to its great abundance the red colour
of some stagnant waters. Its presence explains the pretended miracle of
water changing into blood, which was frequently invoked by the Egyptian
priests.


CILIATE INFUSORIA.

Let us now take a glance at some of the more remarkable species of
Ciliate Infusoria. The bodies of these creatures are all more or less
translucent. They have not substance enough, in fact, to reach a state
of opacity. Their bodies are more or less globular or ovoid, sometimes
fashioned like a shuttle, or curved while growing, sometimes swollen in
the middle like an ampulla, or bell-shaped, and flattened into a discoid
shape; some slightly resemble a tadpole, a thimble, a shoe, a rose-bud,
a flower, even a seed.

[Illustration: Fig. 37. Cothurnia pyxidiformis (Udckem).]

The Paramecians have a soft flexible body, usually of oblong form, and
more or less depressed. They are provided with a loose reticulated
covering, through which issue numerous vibratile cilia, arranged in a
regular series. They were known to the older naturalists; and it is in
this group that organization is carried to the highest perfection it
attains among the Infusoria. The Paramecium possess, besides their
reticulated and contractile tegument, cilia disposed in such a manner as
to serve at once for locomotion, for prehension, that is, for seizing
its food, and as a means of respiration. They are furnished with a
mouth, at the bottom of which the whorl excited by the cilia determines,
according to Dujardin, the hollowing out of a cavity, formed after the
manner of a cul-de-sac, and also the formation of _vacuoles_ with
permanent partitions, in which are enclosed the substances which the
animalcules have swallowed along with the water.

[Illustration: Fig. 38. Paramecium bursaria (Pritchard).]

The Paramecium are propagated by spontaneous division, as already
described. They abound, as we have said, in stagnant water, or in pure
water which is occupied by aquatic plants, sometimes in such prodigious
quantities that they become troublesome. They occur also in flower vases
where the water is not frequently renewed.

The species of this genus have an oblong compressed body, with an
oblique longitudinal fold, directed towards the mouth, which is
lateral. They are sufficiently large to be observed by the common lens,
or eye-glass. _Paramecium aurelia_ appears chiefly in vegetable
infusions. It is common in ditches and moats with aquatic plants.

Humboldt's assertion is fully verified in the case of the Infusoria
under consideration, which is often found with its parasites. These are
small creatures, cylindrical in form, and provided with suckers.
Swimming vigorously in the water, they devote themselves to chasing the
Paramecium. When they have overtaken the fugitive, they throw themselves
upon it, and establish themselves there. They soon multiply in the
interior of its body, and their starving progeny suck and devour the
unfortunate animalcule, which serves them at once for dwelling-house and
larder.

[Illustration: Fig. 39. Condylostoma patens (Duj.), magnified 350
times.]

Another of the parasites which prey upon the Paramecium, in place of
pursuing it, remains perfectly quiet until one of these approach, when
it throws itself upon its victim, and is carried along with it. It
buries itself in the body of the Paramecium, and, in a short time,
multiplies to such a degree, that sometimes fifty of them are found on a
single individual. Poor victim!

The _Nassula_ have the body entirely covered with cilia; they are ovoid
or oblong in form, contractile, the mouth placed laterally and dentate,
or surrounded with a band of horny bristles, the band dilating and
contracting according to the size of the prey which it would swallow. It
either advances to seize the prey, which the movement of vibratile cilia
have failed to draw within the vortex of its mouth, or, as in the case
of the Paramecium, it is sometimes obliged to seek for its prey. These
curious infusoria live in stagnant waters, feeding on the débris of
aquatic plants, from which they draw their chief nourishment as well as
their colour.

The _Bursarians_ are animals with an oval or oblong contractile body,
provided also with vibratile cilia, especially on the surface, having
also a large mouth, surrounded with cilia, forming a sort of microscopic
moustache, spirally arranged.

Among the species belonging to this group may be noted the _Condylostoma
patens_ (Fig. 39), remarkable for its size and voracity. It sometimes
attains the twelfth of an inch, and abounds on every shore from the
Mediterranean to the Baltic. Another Bursarian, a species of
_Plagiostoma_, lives between the intestines and the external muscular
bed of the earth-worm, _Lumbricus terrestris_. To the group of
_Urceolarians_ belong the _Stentors_, which are in number the most
numerous of the Infusoria; they are, for the most part, visible to the
naked eye.

[Illustration: Fig. 40. Stentor Muelleri (Enr.), magnified 75 times.]

The _Stentors_ are inhabitants of fresh, tranquil water, not subject to
agitation, and covered with water plants. They are nearly all coloured
green, blackish, or blue; their bodies covered with cilia. They are
eminently contractile, and very variable in form. They can attach
themselves temporarily, by means of the cils at their posterior
extremities, when they assume a trumpet-like form, the bell of which is
closed by a convex membrane, the edge being furnished with a row of very
strong obliquely-placed cilia, ranged in a spiral, meeting at the mouth,
which is placed near this edge. When they swim freely, they alternately
resemble a club, a spindle, or a sphere. The _Stentor Muelleri_ is seen
in ponds in the neighbourhood of Paris and elsewhere; it has been found
even in the basins of the Jardins des Plantes (Fig. 40).

The animals which constitute this genus are fixed in the first part of
their existence, but free in the second. So long as they are fixed, they
resemble, in their expanding state, a bell or funnel, with the edges
reversed and ciliate. When they become free, they lose their crown of
cilia, take a cylindrical form, more or less ovoid and elongated, and
move themselves by means of a new organ. "There is no animal," says
Dujardin, "which excites our admiration in a higher degree than the
Vorticellate Infusoria, by their crown of cilia, and by the vortex which
it produces; by their ever-varying forms; above all, by their _pedicle_,
which is susceptible of rapid spiral contraction, by drawing the body
backward and again extending it. This _pedicle_ is a flat membranous
band, thicker upon one of its edges than the other, and containing on
the thicker side a continuous channel, occupied, at least in part, by a
fleshy substance, analogous to that of the interior of the body. During
contraction, this thick edge is shortened more than the thin side, and
hence results the precise form of the spiral of the corkscrew."

We cannot conclude our brief history of these curiously-organized beings
without recording the doubt which still exists in the minds of our most
eminent naturalists, whether some of those we have named are animal or
vegetable in their origin. The _Desmideæ_, long classed among animals,
are now generally recognized as plants. The group of _Diatomaceæ_ are
still considered doubtful, and the Monads and _Volocina_ are still
subjects of discussion, the evidence inclining in favour of those who
argue for their vegetable nature. Messrs. Busk, Williamson, and Cohn,
have published in the "Microscopical Transactions" minute details of the
evolutions of these curiously-organized globules, which seem to prove
their vegetable nature. On the other hand, it is difficult to imagine so
accurate an observer as Agassiz writing so positively as he does on a
doubtful subject. Remarking on a former paper, in which he had shown
that the embryo hatched from the egg of a Planaria was a true
polygastric animalcule of the genus Paramecium, he adds, that in former
writers a link was wanting, viz., tracing the young hatched from the egg
of _Distoma_. "This deficiency," he says, "I can now fill. It is another
_Infusorium_, a genuine _Opalina_. With such facts before us there is no
longer any doubt left respecting the character of all these Polygastria;
they are the earliest larvæ condition of worms." Amid these friendly
disputes we congratulate ourselves that we have to do with the oceanic
creations, both animal and vegetable.



CHAPTER V.

POLYPIFERA.

     "Happy is he who, satisfied with his humble fortune, lives
     contentedly in the obscure state where God has placed
     him."--RACINE.


Entering on the class Polypifera, we leave the domain of the infinitely
small to enter the world of the visible. Beside the Infusoria, the
Polypifera, which are sometimes several inches in length, are very
important beings. Science has made great advances towards giving us an
exact knowledge of these singular animals. Many scientific prejudices
have been dissipated, many errors have been corrected. The Polyps, as
they are defined in the actual state of Science, correspond not only
with the _Polypes, properly so called_, of Cuvier and De Blainville, but
also with the _acalephous zoophytes_ of the same authors. We now know
that certain Polyps engender _medusæ_, or acalephous zoophytes, and that
there exist some medusæ scarcely differing in their structure and habits
of life from the ordinary Polyps.

Thus regarded, the Polyps comprehend a great variety of animals, the
bodies of which are generally soft or gelatinous substances. The
principal and smaller divisions, to the number of more than two, are
arranged round an imaginary axis, represented by the central part of the
body. These divisions of the body have in their ensemble the appearance
of a regular cylinder, of a truncated cone, or of a disk. They are
invested with a skin or envelope of calcareous or siliceous corpuscles,
and even a portion of the deepest-lying tissues may be invaded by a
calcareous deposit, the mass of which belongs sometimes to an
individual; sometimes it is common to many, constituting what Dr.
Johnston calls the Polypidom, of which Professor Grant says, "there is
but one life and one plan of development in the whole mass, and this
depends, not on the Polypi, which are but secondary, and often deciduous
parts, but on the general fleshy substance of the body;"[5] "the
ramifications," says Dr. Johnston, "being disposed in a variety of
elegant plant-like forms. The stem and branches are alike in texture:
slender, horny, fistular, and almost always jointed at short and regular
intervals, the joint being a mere break in the continuity of the sheath,
without any character of a proper hinge, and formed by regular
periodical interruptions in the growth of the polypidoms. Along the
sides of these, or at their extremities, we find the denticles or
cup-like cells of the polypi arranged in a determinate order, either
sessile or elevated on a stalk." Near the base of each of these there is
a partition or diaphragm, on which the body of the polyps rests, with a
plain or tubulous perforation in the centre, through which the
connection between the individual polyps and the common medullary pulp
is retained. Besides the cells, there are found at certain seasons a
larger sort of vesicle, readily distinguished from the others by their
size, and the irregularity of their distribution, which are destined to
contain and maturate the ovules.

With these animals the digestive tube is very simple, and presents only
one distinct orifice; the same opening serving at once for receiving the
food and the expulsion of the residuum of digestion. This is one of
Nature's economies, which it is not for us to dispute: we must record it
without further remark.

In nearly all the Polyps the sexes are separate; the generation is
sometimes sexual; but these beings multiply also by what the zoologists
call gemmation, or buds. They are provided with organs of the senses;
nearly all of them have eyes--an immense progress in organization as
compared with the animals which have hitherto engaged our attention.
Their respiration is effected by the skin--another instance of the
economy of Nature. The apparatus of their circulation is indistinct, but
they have a nourishing fluid analogous to the blood in vertebrated
animals. Vibratile cilia and stinging hairs often cover the entire
surface of the Polyps.

These general remarks may appear obscure and insufficient to the larger
number of our readers. They are necessarily so; they are generalities
upon animals very little known, even to naturalists. We quit this
difficult ground, trusting to make the special study of the several
types we shall have to describe more interesting. The group of Polyps
divide themselves into many classes, namely, the _Alcyonidæ_, the
_Zoanthina_, the _Discophora_, and _Ctenophora_. It will be our task to
describe in succession the habits and characters of each of these
classes, dwelling on such species as appear to us to offer to the reader
most real interest.


FOOTNOTES:

[Footnote 5: "Outlines of Comparative Anatomy."]



CHAPTER VI.

CORALLINES.

     "As for your pretty little seed-cups or vases, they are a sweet
     confirmation of the pleasure Nature seems to take in superadding
     elegance of form to most of her works. How poor and bungling are
     all the imitations of art! When I have the pleasure of seeing
     you next, we shall sit down--nay, kneel down--and admire these
     things."--HOGARTH TO ELLIS.


The Alcyonaria are so designated from their principal type, that of the
Alcyons. The fresh-water species are composed of a fleshy, sponge-like
mass, consisting of vertical, aggregated, membranaceous tubes, which are
open on the surface. In these tubes the polyps, which are Isidians, are
located. The mouth is encircled with a single series of filiform
tentacula, which, like those of the whole family, are depressed or
incomplete on one side. The eggs are contained in the tubes, and are
coriaceous and smooth. The tentacula of these polyps are generally
eight, disposed somewhat like the barbs of a feather, and toothed on
their edges like a saw, which has procured them the name of
_Ctenoceros_, from the Greek word χτεις, a comb. Their bodies present
eight perigastric lamellæ; their coral is often formed of spiculæ. We
shall see, farther on, that among the Gorgonidæ the coral ceases to be
parenchymous--that is, spongy and cellular; that its axis assumes a
horny and resistant consistence, which becomes stony in the corallines.
In this last group, the external bed, which is the special lodging of
the polyps, always remains soft on the surface. We shall have a general
idea of the organization, manners, and mode of multiplication among the
Alcyonaria when we come to treat of corals and their strange history.
The class Alcyonaria is divided into many orders. We shall consider--I.
The _Tubiporinæ_. II. The _Gorgoniadæ_. III. The _Pennatulidæ_. IV. The
_Alcyonaria_, properly so called.


I. THE TUBIPORINÆ

form a group consisting of several species, which live in the bosom of
tropical seas, in which the Coral Islands form so prominent a feature.
The group is exclusively formed of the curious genus _Tubipora_.

[Illustration: Fig. 41. Tubipora musica (Linn.), half the natural size.]

The _Tubipora_ is a calcareous coral, formed by a combination of
distinct, regularly-arranged tubes, connected together at regulated
distances by lamellar expansion of the same material. The aggregate
formation resulting from this combination of tubes constitutes a rounded
mass, which often attains a very considerable size. In Fig. 41 we have a
representation of the zoophyte _Tubipora musica_ and its product, which
is sometimes designated by the vulgar name of Sea-Organ. In the
engraving, 1 is the calcareous product, reduced to half its size; 2, is
a portion in its natural size; 3, the tubes magnified, and containing
the polyp which occupies the summit of the tube, the whole of which
constitutes this curious coral; 4, is the polyp magnified; 5, the head
or collection of tentacula of the individual polyp.

Zoologists of the last century confounded all the species of this genera
inhabiting the tropical seas, making only one species, to which they
gave the name of _Tubipora musica_. But it is now known that there are
many species of _Tubiporæ_, readily distinguishable in a fresh condition
by a difference in the colour of the polyps. The tissue of these
singular beings is of an intensely red colour. The disposition of their
tubes in the style of organ pipes has always attracted the attention of
the curious inquirer into the secrets of Nature.


II. GORGONIADÆ.

Milne Edwards divides this order into three natural groups:--I. The
_Gorgoniadæ_. II. The _Isidians_. III. The _Corallines_.

[Illustration: Fig. 42. The Sea Fan, Gorgonia flabellum (Linn.).]

The _Gorgonians_ are composed of two substances: the one external,
sometimes gelatinous and fugitive; sometimes, on the contrary,
cretaceous, fleshy, and more or less tenacious. Animated with life,
this membrane is irritable and encloses the polyp; it becomes friable
or arenaceous in drying. The second substance, internal and central,
sustains the first, and is called the _axis_. This axis presents a horny
appearance, and was formerly believed to possess chemical characters
analogous to the horns and hoofs of some of the vertebrated animals. It
has recently been asserted that the tissues of these corals consist
essentially of a particular substance which resembles horn, but which is
called _Corneine_. A little carbonate of lime is sometimes found united
with this substance, but never in a sufficient quantity to give it a
stony consistence. This outer covering developes itself in concentric
beds, between the portion of the axis previously formed and the internal
surface of the sclerotic covering.

[Illustration: Fig. 43. Fan Gorgon, magnified.]

The mode of growth in this axis presents great variations. Sometimes it
remains simple and rises like a slender rod, sometimes it has numerous
branches. It is _arborescent_ when the branches and their accompaniments
take different directions so as to constitute tufts. It is _panicled_
when they arrange themselves on both sides of the stem or principal
branches, after the manner of the barbs of a feather. It is
_flabelliform_ when the branches rise irregularly under the same plane;
_reticulated_, when branches are so disposed as to be attached to each
other by network in place of remaining free.

The _Gorgoniadæ_ are found in every sea, and always at considerable
depths. They are larger and more numerous between the Tropics than in
cold or even temperate climates. Some of these corals scarcely attain
the twelfth of an inch in height, while others rise to the height of
several feet.

[Illustration: Fig. 44. Gorgonia verticellata (Pallas).]

Formed in the bosom of the ocean, it is only necessary to behold these
singular creations in order to admire the brilliant colours which
decorate their semi-membranaceous branches. The brilliancy of their
robes are singularly diminished, have almost entirely disappeared,
indeed, when they make their appearance in the cases of our natural
history collections.

The _Fan Gorgon_, from the Antilles (Fig. 42), is a species which often
attains the height of eighteen or twenty inches, and nearly as much in
breadth. The network of its interstices with its unequal and serried
meshes, resembling fine lace, have led to its designation of _Sea Fan_.
Its colour is yellow or reddish. In Fig. 43 we have the _Sea Fan_
magnified to twice its natural size, showing the curious details of its
organization.

[Illustration: Fig. 45. Gorgonia verticellata (Pallas), magnified four
times.]

The Whorled Gorgon (_G. verticellata_), which is found in the
Mediterranean, is yellowish in colour, and also of elegant form. It is
sometimes called the Sea Pen. This species is represented in Fig. 44,
while Fig. 45 represents a small branch magnified four times, in order
to give an exact idea of its form.

The Gorgons are not known to be useful either in the arts or in
medicine. They are ornamental in cabinets, and interesting both as
objects of study and of zoological curiosity.


ISIDIANS.

The _Isidæ_ constitute an intermediate group between the _Gorgons_ and
_Corallines_. Their polypidom is arborescent, but its axis is formed of
articulations alternately calcareous and horny. The principal genus is
that of the _Isis_, which is met with in the Indian Ocean, on the
American coast, and in Oceania. The inhabitants of the Molucca Islands
use these animals medicinally as a remedy in certain diseases; but as
they use them for the most opposite maladies, it may be doubted if they
are really efficacious in any medicinal point of view.

The _Isis corolloïdis_ of Oceania has a coral with numerous slender
branches, furnished with cylindrical knots at intervals, contracted
towards the middle, finely striated, and rose-coloured. _Isis_
_hippuris_, represented in Fig. 46, has a singular resemblance to the
Common Mare's Tail (_Hippuris vulgaris_).

[Illustration: Fig. 46. Isis hippuris.]

Four other species of Isidians are known. The same family includes the
genera of _Melitæa_ and _Mopsea_, which, however, our limits forbid us
to describe.


CORALLINÆ.

The group of Corallines consist of a single genus, _Corallium_, having a
common axis, inarticulate, solid, and calcareous, the typical species of
which furnishes matter hard, brilliant, and richly coloured, and much
sought after as an object of adornment. This interesting zoophyte and
its product require to be described with some detail.

From very early times, the coral has been adopted as an object of
ornament. From the highest antiquity, also, efforts were made to
ascertain its true origin, and the place assignable to it in the works
of Nature. Theophrastus, Dioscorides, and Pliny considered that the
coral was a plant. Tournefort, in 1700, reproduced the same idea.
Réaumur slightly modified this opinion of the ancients, and declared his
opinion that the coral was the stony product of certain marine plants.
Science was in this state when a naturalist, who has acquired a great
name, the Count de Marsigli, made a discovery which threw quite a new
light on the true origin of this natural product. He announced that he
had discovered the flowers of the coral. He represented these flowers in
his fine work, "La Physique de la Mer," which includes many interesting
details respecting this curious product of the ocean. How could it be
longer doubted that the coral was a plant, since he had seen its
expanded flowers?

No one doubted it, and Réaumur proclaimed everywhere the discovery of
the happy Academician.

Unhappily, a discordant note soon mingled in this concert. It even
emanated from a pupil of Marsigli!

Jean André de Peyssonnel was born at Marseilles in 1694. He was a
student of medicine and natural history at Paris when the Académie des
Sciences charged him with the task of studying the coral on the
sea-shore. Peyssonnel began his observations in the neighbourhood of
Marseilles in 1723. He pursued it on the North African coast, where he
had been sent on a mission by the Government. Aided by a long series of
observations as exact as they were delicate, Peyssonnel demonstrated
that the pretended flowers which the Count de Marsigli thought he had
discovered in the coral, were true animals, and showed that the coral
was neither plant nor the product of a plant, but a being with life,
which he placed in the first "rung" of the zoological ladder. "I put the
flower of the coral," says Peyssonnel, "in vases full of sea-water, and
I saw that what had been taken for a flower of this pretended plant was,
in truth, only an insect, like a little sea-nettle, or polyp. I had the
pleasure of seeing removed the claws or feet of the creature, and having
put the vase full of water, which contained the coral, in a gentle heat
over the fire, all the small insects seemed to expand. The polyp
extended his feet, and formed what M. de Marsigli and I had taken for
the petals of a flower. The calyx of this pretended flower, in short,
was the animal, which advanced and issued out of its cell."

The observations of Peyssonnel were calculated to put aside altogether
theories which had lately attracted universal admiration, but they were
coldly received by the naturalists, his contemporaries. Réaumur
distinguished himself greatly in his opposition to the young innovator.
He wrote to Peyssonnel in an ironical tone: "I think (he says) as you
do, that no one has hitherto been disposed to regard the coral as the
work of insects. We cannot deny that this idea is both new and singular;
but the coral, as it appears to me, never could have been constructed by
sea-nettles or polyps, if we may judge from the manner in which you make
them labour."

What appeared impossible to Réaumur was, however, a fact which
Peyssonnel had demonstrated to hundreds by his experiments at
Marseilles. Nevertheless, Bernard de Jussieu did not find the reasons he
urged strong enough to induce him to abandon the opinions he had formed
as to their vegetable origin. Afflicted and disgusted at the indifferent
success with which his labours were received, Peyssonnel abandoned his
investigations. He even abandoned science and society, and sought an
obscure retirement in the Antilles as a naval surgeon, and his
manuscripts, which he left in France, have never been printed. These
manuscripts, written in 1744, were preserved in the library of the
Museum of Natural History at Paris. The title is comprehensive and
sufficiently descriptive. It should be added, in order to complete the
recital, that Réaumur and Bernard de Jussieu finally recognized the
value of the discoveries and the validity of the reasoning of the
naturalist of Marseilles. When these illustrious _savants_ became
acquainted with the experiments of Trembley upon the fresh-water hydræ;
when they had themselves repeated them; when they had made similar
observations on the sea anemone and alcyonidæ; when they finally
discovered that on other so-called marine plants animalcules were found
similar to the hydra, so admirably described by Trembley;--they no
longer hesitated to render full justice to the views of their former
adversary.

While Peyssonnel still lived forgotten at the Antilles, his scientific
labours were crowned with triumph at Paris; but it was a sterile triumph
for him. Réaumur gave to the animalcules which construct the coral the
name of _Polyps_, and _Coral_ to the product itself, for such he
considered the architectural product of the polyps. In other words,
Réaumur introduced into Science the views which he had keenly contested
with their author. But from that time the animal nature of the coralline
has never been doubted.

Without pausing to note the various authors who have given their
attention to this fine natural production, we shall at once direct our
attention to the organization of the animalcules, and the construction
of the coral.

M. Lacaze-Duthiers, professor at the Jardin des Plantes of Paris,
published in 1864 a remarkable monograph, entitled "L'Histoire Naturelle
du Corail." This learned naturalist was charged by the French
Government, in 1860, with a mission having for its object the study of
the coral from the natural history point of view. His observations upon
the zoophytes are numerous and precise, and worthy of the successor of
Peyssonnel; but for close observation, practical conclusions, and
popular exposition, the world is more indebted to Charles Darwin than to
any other naturalist.

A branch of _living_ coral, if we may use the term, is an aggregation of
animals derived from a first being by budding. They are united among
themselves by a common tissue, each seeming to enjoy a life of its own,
though participating in a common object. The branch seems to originate
in an egg, which produces a young animal, which attaches itself soon
after its birth, as already described. From this is derived the new
beings which, by their united labours, produce the branch of coral or
polypidom.

[Illustration: Fig. 47. Living Bed of Coral after the entrance of the
Polyps.

(Lacaze-Duthiers.)]

This branch is composed of two distinct parts: the one central, of a
hard, brittle, and stony nature, the well-known coral of commerce; the
other altogether external, like the bark of a tree, soft and fleshy, and
easily impressed with the nail. This is essentially the bed of the
living colony. The first is called the polypidom, the second is the
colony of polyps. This bed (Fig. 47) is much contracted when the water
is withdrawn from the colony. It is covered with salient mammals or
protuberances, much wrinkled and furrowed.

Each protuberance encloses a polyp, and presents on its summit eight
folds, radiating round a central pore, which presents a star-like
appearance. This pore as it opens gives to the polyps the opportunity of
coming out. Its edge presents a reddish calyx, like the rest of the
bark, the festooned throat of which presents eight dentations.

[Illustration: Fig. 48. Three Polyps of the Coral. (Lacaze-Duthiers.)]

The polyp itself (Fig. 48) is formed of a whitish membranous tube,
nearly cylindrical, having an upper disk, surrounded by its eight
tentacula, bearing many delicate fibres spreading out laterally. This
assemblage of tentacula resembles the corolla of some flowers; its form
is very variable, but always truly elegant. Fig. 49 (which is borrowed
from M. Lacaze-Duthiers' great work) represents one of these forms of
the coral.

[Illustration: Fig. 49. Coral Polyp. (Lacaze-Duthiers.)]

The arms of the polyps are at times subject to violent agitation: the
tentacula become much excited. If this excitement continues, the
tentacula can be seen to fold and roll themselves up, as shown in Fig.
50. If we look at the expanded disk, we see that the eight tentacula
attach themselves to the body, describing a space perfectly circular, in
the middle of which rises a small mammal, the summit of which is
occupied by a small slit like two rounded lips. This is the mouth of the
polyps, the form being very variable, but well represented in Fig. 50,
where the organ under consideration is displayed.

A cylindrical tube connected with the mouth represents the oesophagus or
gullet; but all other portions of the digestive tube are very
rudimentary. The oesophagus connects the general cavity of the body with
the exterior, and looks as if it were suspended in the middle of the
body by certain folds, which issue with perfect symmetry from eight
points of its circumference. The folds which thus fix the oesophagus
form a series of cells, above each of which it attaches itself, and
supports an arm or tentaculum.

[Illustration: Fig. 50. Another form of the Coral Polyp.
(Lacaze-Duthiers.)]

Let us pause an instant over the soft and fleshy bark in which the
polyps are engaged. Let us see also what are the mutual relations which
exist between the several inhabitants of one of these colonies, how they
are attached to one another, and what is their connection with the
polypidom.

The thick fleshy body, soft, and easily impressed with the finger, is
the living part which produces the coral; it extends itself so as
exactly to cover the whole polypidom. If it perishes at any one point,
that part of the axis which corresponds with the point no longer shows
any increase. An intimate relation, therefore, exists between the bark
and the polypidom. If the bark is examined more closely, three principal
elements are recognized--a common general _tissue_, some _spicula_, and
certain _vessels_. The general tissue is transparent, glossy, cellular,
and contractile.

[Illustration: Fig. 51. Coralline Spicula. (Lacaze-Duthiers.)]

The _spiculæ_ are very small calcareous concretions, more or less
elongated, covered with knotted joints bristling with spines, and of
regular determinate form (Fig. 51). They refract the light very vividly,
and their colour is that of the coral, but much weaker, in consequence
of their want of thickness. They are uniformly distributed throughout
the bark, and give to the coral the fine colour which generally
characterises it.

The vessels constitute a network, which extends and repeats itself in
the thickness of the crust. These vessels are of two kinds (Fig. 52);
the one, comparatively very large, is imbedded in the axis, and disposed
in parallel layers; the others are regular and much smaller. They form a
network of unequal meshes, which occupies the whole thickness of the
external crust. This network has direct and important connection with
the polyps on the one hand, and with the central substance which forms
the axis on the other. It communicates directly with the general cavity
of the body of the animal, by every channel which approaches it, while
the two ranges of network approach each other by a great number of
anastomosing processes. Such is the vascular arrangement of the coral.

[Illustration: Fig. 52. Circulating Apparatus for the nutritive fluids
in the Coral. (Lacaze-Duthiers.)]

The circulation of alimentary fluids in the coral is accomplished by
means of vessels near to the axis, without, however, directly
anastomosing with the cavities containing the polyps which live in the
polypidom; they only communicate with those cavities by very delicate
intermediary canals. The alimentary fluids they receive from the
secondary system of network, which brings them into direct communication
with the polyps. The alimentary fluids elaborated by the polyps pass
into the branches of the secondary and irregular network system, in
order to reach the great parallel tubes which extend from one extremity
of the organism to the other, serving the same purpose to the whole
community.

When the extremity of a branch of living coral is torn or broken, a
white liquid immediately flows from the wound, which mingles with water,
and presents all the appearance of milk. This is the fluid aliment which
has escaped from the vessel containing it, charged with the débris of
the organism.

What occurs when the bud produces new polyps? It is only round
well-developed animals, and particularly those with branching
extremities, in which this phenomenon is produced. The new beings
resemble little white points pierced with a central orifice. Aided by
the microscope, we discover that this white point is starred with
radiating white lines, the edge of the orifice bearing eight
distinctly-traced indentations. All these organs are enlarged step by
step until the young animal has attained the shrub-like or branched
aspect which belongs to the compound polypidom. The tube is branching,
and the orifices from which the polypi expand become dilated into
cup-like cells.

[Illustration: Fig. 53. Section of a Branch of Coral.
(Lacaze-Duthiers.)]

The coral of commerce, so beautiful and so appreciated by lovers of
bijouterie, is the polypidom. It is cylindrical, much channeled on the
surface, the lines usually parallel to the axis of the cylinder, the
depressions sometimes corresponding to the body of the animal. If the
transverse section of a polypidom be examined, it is found to be
regularly festooned on its circumference. Towards its centre certain
sinuosities appear, sometimes crossing, sometimes trigonal, sometimes in
irregular lines, and in the remaining mass are reddish folds alternating
with brighter spaces which radiate from the centre towards the
circumference (Fig. 53). In the section of a very red coral, it will be
observed that the colour is not equally distributed, but separated into
zones more or less deep in colour, containing very thin preparations
which crack, not irregularly, but parallel to the edge of the plate, and
in such a manner as to reproduce the festoons on the circumference. From
this it may be deduced that the stem increases by concentric layers
being deposited, which mould themselves one upon the other. In the mass
of coral certain small corpuscles occur, charged with irregular
asperities, much redder than the tissue into which they are plunged.
These are much more numerous in the red than in the light band, and they
necessarily give more strength to the general tint.

[Illustration: Fig. 54. Birth of the Coralline Larvæ.
(Lacaze-Duthiers.)]

To the mode of reproduction in the coral polyps, so well described by
Lacaze-Duthiers, we can only devote a few lines. Sometimes, according to
this able observer, the polyps of the same colony are all either male or
female, and the branch is _unisexual_; in others there are both male and
female, when the branch is _bisexual_. Finally, but very rarely, polyps
are found uniting both sexes.

The coral is viviparous; that is to say, its eggs become embryos inside
the polyp. The larvæ remain a certain time in the general cavity of the
polyp, where they can be seen through its transparency, as exhibited in
Fig. 54. Aided by the magnifying powers of the microscope, coral larvæ
may here be perceived through the transparent membranous envelope. From
this position they escape from the mouth of the mother in the manner
represented in the upper branch. The animal then resembles a little
white grub or worm, more or less elongated. The larva is, however, still
egg-shaped or ovoid; moreover, it is sunk in a hollow cavity, and
covered with cilia, by the aid of which it can swim. Sometimes one of
its extremities becomes enlarged, the other remaining slender and
pointed. Upon this an opening is formed communicating with the interior
cavity: this is the mouth. The larvæ swim backwards; that is to say,
with the mouth behind.

[Illustration: Fig. 55. Very young Polyps, attached to a Bryozoa.]

It is only at a certain period after birth that the coral polyp fixes
itself and commences its metamorphoses, which consist essentially in a
change of form and proportions. The buccal extremity is diminished and
tapers off, whilst the base swells, and is enlarged--it becomes discoid;
the posterior surface of this sort of disk is a plane, the front
representing the mouth, at the bottom of a depression edged with a great
cushion. Eight mammillations or swellings now appear, corresponding to
the chambers which divide the interior of the disk: the worm has taken
its radiate form. Finally, the mammals are elongated and transformed
into tentacula. In Fig. 55 a young coral polyp is represented fixed upon
a bryozoa, a name employed by Ehrenberg for zoophytes having a mouth and
anus. It forms a small disk, the fortieth part of an inch in diameter,
and having its spicula already coloured red. Fig. 56 shows the
successive forms of the young polyps in the progressive phases of their
development--being a young coralline polyp fixed upon a rock still
contracted. Fig. 57 is a similar coralline attached to a rock and
expanding its tentacula. Fig. 58 represents a small pointed rock covered
with polypi and polypidoms of the natural size and of different shapes,
but all young, and indicating the definite form of development which
the collective beings are to assume.

[Illustration: Fig. 56. A young Coral Polyp fixed upon a Rock.
(Lacaze-Duthiers.)]

The simple isolated state of the animal, whose phases of development we
have indicated, does not last long. It possesses the property of
producing new beings, as we have already said, by budding. But how is
the polypidom formed? If we take a very young branch, we find in the
centre of the thickness of the crust a nucleus or stony substance
resembling an agglomeration of spicula. When they are sufficient in
number and size, these nuclei form a kind of stony plate, which is
imbedded in the thickness of the tissues of the animal. These _laminæ_,
at first quite flat, assume in the course of their development a
horse-shoe shape. Figs. 59 and 60 will give the reader some idea of the
form in which the young present themselves. Fig. 59 represents the
corpuscles in which the polypidom has its origin; Fig. 60, the
rudimentary form of the coralline polypidom.

[Illustration: Fig. 57. Young Coral Polyp attached to a Rock and
expanded. (Lacaze-Duthiers.)]

Our information fails to convey any precise notion of the time necessary
for the coral to acquire the various proportions in which it presents
itself.

[Illustration: Fig. 58. A Rock covered with young Polyps and Polypidom.
(Lacaze-Duthiers.)]

Darwin, who examined some of these creatures very minutely, tells us
that "several genera" (Flustræ, Escharæ, Cellaria, Cresia, and others)
agree in having singular movable organs attached to their cells. The
organs in the greater number of cases very closely resemble the head of
a vulture; but the lower mandible can be opened much wider than a real
bird's beak. The head itself possesses considerable powers of movement,
by means of a short neck. In one zoophyte the head itself was fixed, but
the lower jaw free; in another it was replaced by a triangular hood,
with a beautifully-fitted trap-door, which evidently answered to the
lower mandible. In the greater number of species each cell was provided
with one head, but in others each cell had two.

[Illustration: Fig. 59. Corpuscles from which originate the Polypidom.]

[Illustration: Fig. 60. First form of the Polypidom. (Lacaze-Duthiers.)]

"The young cells at the end of the branches of these corallines contain
quite immature polypi, yet the vulture heads attached to them, though
small, are in every respect perfect. When the polypus was removed by a
needle from any of the cells, these organs did not appear to be in the
least affected. When one of the vulture-like heads was cut off from a
cell, the lower mandible retained its power of opening and closing.
Perhaps the most singular part of their structure is, that when there
are more than two rows of cells on a branch, the central cells were
furnished with these appendages of only one-fourth the size of the
outside ones. Their movements varied according to the species; but in
some I never saw the least motion, while others, with the lower mandible
generally wide open, oscillated backwards and forwards at the rate of
about five seconds each turn; others moved rapidly and by starts. When
touched with a needle, the beak generally seized the point so firmly
that the whole branch might be shaken."

In the _Cresia_, Darwin observed that each cell was furnished with a
long-toothed bristle, which had the power of moving very quickly; each
bristle and each vulture-like head moving quite independently of each
other; sometimes all on one side, sometimes those on one branch only
moving simultaneously, sometimes one after the other. In these actions
we apparently behold as perfect a transmission of will in the zoophyte,
though composed of thousands of distinct polyps, as in any distinct
animal. "What can be more remarkable," he adds, "than to see a
plant-like body producing an egg, capable of swimming about and choosing
a proper place to adhere to, where it sprouts out into branches, each
crowded with innumerable distinct animals, often of complicated
organization!--the branches, moreover, sometimes possessing organs
capable of movement independent of the polypi."

       *       *       *       *       *

Passing to the coral fishing, it may be said to be quite special,
presenting no analogy with any other fishing in the European seas, if we
except the sponge fisheries. The fishing stations which occur are found
on the Italian coast and the coast of Barbary; in short, in most parts
of the Mediterranean basin. In all these regions, on abrupt rocky beds,
certain aquatic forests occur, composed entirely of the red coral, the
most brilliant and the most celebrated of all the corals, _Coralium
decus liquidi_! During many ages, as we have seen, the coral was
supposed to be a plant. The ancient Greeks called it the _daughter of
the sea_ (Κορύλλιου κόρη ἁλός), which the Latins
translated into _corralium_ or _coralium_. It is now agreed among
naturalists that the coral is constructed by a family of polyps living
together, and composing a polypidom. It abounds in the Mediterranean
and the Red Sea, where it is found at various depths, but rarely less
than five fathoms, or more than a hundred and fifty. Each polypidom
resembles a pretty red leafless under shrub bearing delicate little
star-like radiating white flowers. The axes of this little tree are
the parts common to the association, the flowrets are the polypi.
These axes present a soft reticulated crust, full of little cavities,
which are the cells of the polyps, and are permeated by a milky juice.
Beneath the crust is the coral, properly so called, which equals marble
in hardness, and is remarkable for its striped surface, its bright red
colour, and the fine polish of which it is susceptible. The ancients
believed that it was soft in the water, and only took its consistence
when exposed to the air:--

    "Sic et coralium, quo primum contigit auras
    Tempore, durescit."

    OVID.

The fishing is chiefly conducted by sailors from Genoa, Leghorn, and
Naples, and it is so fatiguing, that it is a common saying in Italy that
a sailor obliged to go to the coral fishery should be a thief or an
assassin. The saying is a gratuitous insult to the sailor, but conveys a
good idea enough of the occupation.

The barks sent to the fishing range from six to fifteen tons; they are
solid, and well adapted for the labour; their rig is a great lateen
sail, and a jib or staysail. The stern is reserved for the capstan, the
fishers, and the crew. The fore part of the vessel is reserved for the
requirements of the patron or master.

The lines, wood, and irons employed in the coral fisheries are called
the _engine_: it consists of a cross of wood formed of two bars,
strongly lashed or bolted together at their centre; below this a great
stone is attached, which bears the lines, arranged in the form of a sac.
These lines have great meshes, loosely knotted together, resembling the
well-known swab.

The apparatus carries thirty of these sacs, which are intended to
grapple all they come in contact with at the bottom of the sea. They are
spread out in all directions by the movement of the boat. The coral is
known to attach itself to the summit of a rock and to develop itself,
forming banks there, and it is to these rocks that the swab attaches
itself so as to tear up the precious harvest. Experience, which in time
becomes almost intuitive, guides the Italian fisher in discovering the
coral banks. The craft employed in the great fishery have a "patron" or
captain, the bark having a poop, with a crew of eight or ten sailors,
and in the season it is continued night and day. The whole apparatus,
and mode of using it, is shown in PL. III.

When the patron thinks that he has reached a coral bank, he throws his
engine overboard. As soon as the apparatus is engaged, the speed of the
vessel is retarded, the capstan is manned by six or eight men, while the
others guide the helm and trim the sails. Two forces are thus brought to
act upon the lines, the horizontal action of the vessel and the vertical
action of the capstan. In consequence of the many inequalities of the
rocky bottom, the engine advances by jerks, the vessel yielding more or
less, according to the concussion caused by the action of the capstan or
sail. The engine seizes upon the rugged rocks at the bottom, and raises
them to let them fall again. In this manner the swab, floating about,
penetrates beneath the rocks where the coral is found, and is hooked on
to it. To fix the lines upon the coral and bring them home, is a work of
unheard-of labour. The engine long resists the most energetic and
repeated efforts of the crew, who, exposed almost naked to the burning
sun of the Mediterranean, work the capstan to which the cable and engine
are attached, while the patron urges and excites them to increased
exertion, and the sailors trim the sail and sing with a slow and
monotonous tone a song, the words of which improvise in a sort of
psalmody the names of the saints most revered among the seafaring
Italian population.

[Illustration: Plate III.--Coral Fishing on the Coast of Sicily.]

The lines are finally brought home, tearing or breaking blocks of rock,
sometimes of enormous size, which are brought on board. The cross is now
placed on the side of the vessel, the lines are arranged on the deck,
and the crew occupy themselves in gathering the results of their labour.
The coral is gathered together, the branches of the precious zoophyte
are cleansed, and divested of the shells and other parasitic products
which accompany them; finally, the produce is carried to and sold in the
ports of Messina, Naples, Genoa, or Leghorn, where the workers in
jewellery purchase them. Behold, fair reader, with what hard labour,
fatigue, and peril, the elegant bijouterie with which you are decked is
torn from the deepest bed of the ocean!


III. THE PENNATULIDÆ, OR SEA-PEN.

This curious family received from Cuvier the name of _Swimming Polypi_,
and from Lamarck that of _Floating Polypi_. The name of Pennatulæ, by
which they are generally known, is taken from their resemblance to a
quill, _penna_. In the words of Lamarck, "It seems as if Nature, in
forming this composite animal, had wished to copy the external form of a
bird's feather." Our fishermen call it the _cock's comb_, which is not
inapt, but less expressive of its peculiarities. This animal is "from
two to four inches in length, of a uniform purplish-red colour, except
at the hip or base of the stalk, where it is pale orange-yellow; the
skin is thickish, very tough, and of a curious structure, being composed
of minute crystalline cylinders, densely arranged in straight lines, and
held together by a tenacious glutinous matter, the cylinders being about
six inches in diameter, in length straight and even, or sometimes
slightly curved, and of a red colour, which communicates itself to the
zoophyte." (Johnston.) The animals by which it is formed constitute
colonies, which, however, are only attached to the rocks by an enlarged
basis; it appears to live generally at the bottom of the sea; its root,
if we can use the term, buried in the sands or mud; its polypiferous
portion sallying out into the water. The agitation of the waves and the
fishermen's nets often displace these aggregates of creation, and then
they float at various depths in the bosom of the ocean.

The stalk of the polypidom is hollow in the centre, having a long
slender bone-like substance, which is white, smooth, and square, but
tapering at each extremity to a fine point. The polyps, which are fleshy
and white, are provided with eight long retractile tentacula,
beautifully ciliated on their inner edge with two series of short
processes strengthened with crystalline spicula. The mouth in the centre
of the tentacula is somewhat angular, bounded by a white ligament, a
process from which encircles the base of each tentaculum, which thus
seems to issue from an aperture. The ova lie between the membranes of
the pinnæ; they are globular, of a yellowish colour, and by a little
pressure can be made to pass through the mouth. The polyps are
distributed with more or less regularity in such a manner that one of
the extremities of the common axis is always naked: this part has been
compared to the tubulous part of a feather. The stem, common to the
colony, is a solid central axis, more or less developed, which is
covered with a fleshy fibrous substance, susceptible of dilatation and
contraction.

The _Pennatulidæ_ comprehend three genera; namely, those with polyps on
bipinnate wings, having--according to Dr. Johnston--

    Polypidoms plumose, in                  Pennatula.
    Polypidoms virgate, or wand-shaped      Virgularia.
    Polypi, unilateral and sessile        }
    Polypidom, linear-elongate.           } Pavonaria.

In the genus _Pennatula_, the polyps are disposed in transverse rows
upon the outer and inner edge, in a series of prolongations in the form
of a feather. These winged species of polypidom are somewhat
scythe-shaped, well developed, and furnished with a great quantity of
pointed spiculæ, which are constituted of bundles at the base of the
calyx. The space between the two rows of appendages is sometimes a
tissue, sometimes scaly, sometimes granulous. Of the _Pennatula_ five
species are known, and all of them appear to be gifted with
phosphorescent properties. We may note among these species _Pennatula
spinosa_ (Fig. 61), which inhabits the Mediterranean, and takes its name
from its colour; _Pennatula phosphorea_, which abound in most European
seas, being found in great plenty, clinging to the fishermen's lines
round our own northern shores, more especially when they are baited with
mussels.

_P. phosphorea_ is of a reddish purple, the base of the smooth stalk
pale; the raches roughened with close-set papillæ, and furrowed down
the middle; pinnæ close; polyp cilia uniserial, tubular, with spinous
apertures. (Sibbald.)

Bohadsch says the _Pennatulæ_ swim by means of their pinnæ, which they
use as fishes do their fins. Ellis says, "It is an animal that swims
about in the sea, many of them having a muscular motion as they swim
along;" these motions being effected, as he tells us in another place,
by means of the pinnules or feather-like fins, "evidently designed by
Nature to move the animal backward or forward in the sea." Cuvier tells
us they have the power of moving by the contraction of the fleshy part
of the polypidom, and also by the combined action of its polyps. Dr.
Grant says, "A more singular and beautiful spectacle could scarcely be
conceived than that of a deep purple _P. phosphorea_ with all its
delicate transparent polypi expanded, and emitting their usual brilliant
phosphorescent light, sailing through the still and dark abyss, by the
regular and synchronous pulsations of the minute fringed arms of the
whole polypi;" while Linnæus tells us that "the phosphorescent sea-pens
which cover the bottom of the ocean cast so strong a light, that it is
easy to count the fishes and worms of various kinds which sport among
them."

[Illustration: Fig. 61. Sea-pen, Pennatula spinosa. (Edes.)]

Lamarck, Schweigger, and other naturalists, however, reasoning from what
is known of other compound animals, deny the existence of this
locomotive power in these zoophytes; "and there is little doubt," says
Dr. Johnston, "that these authors are right, for, when placed in a basin
of sea water, the _Pennatulæ_ are never observed to change their
position; they remain in the same spot, and lie with the same side up or
down, just as they have been placed. They inflate the body until it
becomes to a considerable degree transparent, and only streaked with
intercepted lines of red, which distend at one place and contract at
another; they spread out the pinnæ, and the polyps expand their
tentacula, but they never attempt to swim, or perform any process of
locomotion."

_P. mirabilis_ is common in the east and north coasts of Scotland.

The _virgularias_ differ from the _pennatula_ chiefly in their
development, relative to the axis of the colony and the shortness of the
pinnæ, which carry the polyps; and in this, that no spiculæ enter into
the composition of its softer parts. _V. mirabilis_ is found in the
North Sea, on the coast of Scotland, and as far north as Norway. In
Zetland it is known as the sea-rush. It is abundant in Belfast Lough,
but, from its brittle nature, perfect specimens are difficult to obtain.

"It seems," says Sowerby, "to represent a quill stripped of its
feathers. The base looks like a pen in this as in other species,
swelling a little way from the end, and then tapering. The upper part is
thicker, with alternate semicircular pectinated swellings, larger
towards the middle, tapering upwards, and terminating in a thin bony
substance, which passes through the whole extent, and is from six to ten
inches in length."

In a communication to Dr. Johnston, from Mr. R. Patterson of Belfast,
commenting on Müller's figure of _Virgularia_, he tells us that in the
longest specimen he had, no two plumes were precisely alike--so unlike,
indeed, that the artist copying one, could not for a moment hesitate,
after raising her eyes from her paper, to look at the animal, as to
which she was copying.

Its short waving and deeply dentated wings are of a brilliant yellow.
The polyps, which appear upon their lobes, are whitish, transparent, and
form a fringe of small diaphanous white stars (Figs. 62 and 63). We may
figure to ourselves a slender wand-like and much-elongated polypidom,
carrying only a non-contractile polyp on one side, which would give us
an idea of the Pavonaria, of which we know only one species, which is
from the Mediterranean.

_Virgularia mirabilis_ is undoubtedly one of the finest polypidoms found
in the ocean. Two series of half-moon shaped wings, obliquely
horizontal, are placed symmetrically round an upright axis. They embrace
the stem somewhat in the manner termed _petiolate_ by botanists,
clasping it alternately; or, shall we say, like two broad ribbons rolled
round a stem in an inverse direction, in such a manner as to produce
the effect of two opposing flights of stairs. These wings are waving,
vandyked, and fringed on their outer edge, and of a brilliant yellow;
the dentature of the fringe being the lodging of their pretty little
polyps, which display occasionally their gaping mouths and expanded
gills. The polyps are white and semi-transparent. When they display
their rays, the margin of each wing presents an edging of silvery stars.

[Illustration: Fig. 62. Loose-winged Virgularia, Virgularia mirabilis
(Lamarck).]

[Illustration: Fig. 63. Branch of Virgularia, enlarged.]

The _Umbellularia_ have a very long stem, supported by a bone (Fig. 64)
of the same length, and terminated at the summit only by a cluster of
polyps. They have been found in the Greenland and other northern seas.

[Illustration: Fig. 64. Umbellularia Greculandrea (Lamarck).]

The _Veretillum_, which inhabit the Mediterranean (Fig. 65), have a
simple cylindrical body, without branchiæ, and a rudimentary polypidom,
furnished with very large polyps of a whitish colour.


IV. THE ALCYONARIA PROPER.

The beings which compose this group have the fleshy polypidom always
adherent, without axis or solid interior stem. They are divided into
four families or tribes. One of these, the _Cornularia_, are zoophytes,
and live in isolation, or gathered together in small numbers on the
surface of a common membraniform expansion. The _Cornularia cornucopia_
live on the coast of Naples, _C. crassa_ on the Algerian coast. Other
genera make their appearance on the coast of Scotland, of Norway, in the
Red Sea, and in the Indian Ocean they appear in great numbers.

[Illustration: Fig. 65. Veretillum cynomorium (Lamarck).]

In the _Alcyonaria_, properly so called, the polypidom is very thick, of
a semi-cartilaginous consistence, granular, and rough to the touch.

The genus _Alcyonium_ is numerous in species and widely dispersed. _A.
digitatum_ is very common on our coasts, and on many parts of the coast
scarcely a stone or shell is dredged up from deep water which does not
serve as a support to some one or more species of _Alcyonium_. It is
known by various popular names by our sea-side population, such as
_cow's paps_, from its resemblance to the teats of the cow--_dead man's
fingers_, from the occasional resemblance of its finger-like lobes to a
man's fingers.

The polypidom is a simple obtuse process, the outer skin of which is
tough and coriaceous, studded all over with star-like figures, which on
examination are found to be divided into eight rays, indicating the
number of the polyps enclosed in its transparent vesicular membrane. It
is dotted with minute calcareous grains, and marked with eight
longitudinal lines or septa, stretching between the membrane and the
central stomach, which divide the intermediate space into an equal
number of compartments. These lines not only extend to the base of the
tentacula, but run across the anal disk, and terminate in a central
mouth. The tentacula are short, obtuse, ciliate on the margins, and
strengthened at their roots by numerous crystalline spiculæ. The polyp
cells are oval, placed just under the skin, and are the terminating
points of certain long canals which traverse the whole polypidom. The
polyps, which are distributed over the whole surface, can withdraw into
the cavities; they are, besides, of an extremely vital sensibility: the
least shock impresses itself on the tentacula, the impulse of a wave
even producing contraction; in response, the animal, which is well
developed, sallies out perceptibly, but immediately retires again to
hide itself in the cell.

We find on the coast, in the Channel, and in the North Sea, _Alcyonium
digitatum_, the mass of which is of a reddish white, ferruginous, or
orange; _A. stellatum_, found on the shores of the Mediterranean, is
expanded in its upper part, narrow towards its base, very rough on the
surface, and rose-coloured; _A. palmatum_, is cylindrical, branching at
the summit, of a deep red, except at the base, where it is yellow: this
is met with in the Mediterranean.

We may note as a type, altogether different from any yet touched upon,
the _Nephtys_, in which the polypidom is a coriaceous tissue bristling
with spiculæ over its whole surface. In _N. Chabroli_, the polypidom is
squat, with thick spreading arms covered with lobiliform branches, the
tubercular polypidom of which are columnar and obtuse, the sicula green,
and the tentacula of the polyps yellow.

"On a cursory view," says Dr. Johnston, "the polypodium of the three
families embraced appear very dissimilar, and accordingly, by many
recent authors, they have been scattered over the class, and placed
widely asunder. The affinity between them, however, is generally
acknowledged, and had been distinctly perceived by some of the earliest
zoophytologists. Thus Bohadsch found so much in common in the typical
pennatulæ and a species of _Alcyonium_, that he has not hesitated to
describe them as members of the same genus; and, although the more
systematic character of Pallas prevented him from falling into this
error, if error it can be called, he did not the less recognize the
relationship between the genera or families. Pallas also tells us that
his _Pennatula cynomorium_ differs from the _Alcyonium_ only in this,
that the former is a movable and the latter a fixed polypidom; and he
saw with equal clearness the connection which exists between these
genera and the shrub-like _Gorgonia_. Of the _Pennatula mirabilis_ he
had doubts whether it was not rather a species of _Gorgonia_, until he
perceived that the stem was attenuated at each end, and free; and of the
Sea-pens generally, Ellis remarks that they are 'a genus of zoophytes
not far removed from the _Gorgonias_, on account of their polyp mouths,
as well as having a bone in the inside and flesh without.' 'On the other
hand, the _Gorgoniæ_ seem,' says Pallas, 'with the exception of their
horny skeleton, to be nearly similar in structure to the _Alcyonia_; but
as there are species of _Gorgonia_ which are suberose internally, and
almost of a uniform medullary consistence, even this mark of distinction
fails to separate the tribes, and we have little left to guide us in
arranging these esculent species excepting their external habits.'"

"With most corallines," says Frédol, "the elementary individual, in
spite of the adhesion established among them, possesses a vital energy
all its own; it is in some respects quite independent. They have each
its own particular will, which it is difficult to mistake for a common
will; but it is not thus with the _Pennatula_. Their association
consists of a non-adherent polyp, which moves--obscurely, it is
true--but still it moves. To what does this lead? To this: that the
parts which they possess in common, in place of being horny or
calcareous--that is, completely inert--are fleshy, with contractile
powers; that is to say, animated. Consequently, the polyp of the
_Pennatula_ are less independent of each other than the coral polyp,
which have a central, perhaps a sensible organ, common to all, which
binds them to each other, giving a certain unity to their acts. The
Coralline polyps have no will; the _Pennatula_ have."



CHAPTER VII.

ZOANTHARIA, OR ANIMAL FLOWERS.

          "I saw the living pile ascend
    The mausoleum of its architects,
    Still dying upwards as their labour closed:
    Slime the material, but the slime was turned
    To adamant by their petrific touch."

    MONTGOMERY'S _Pelican Island_.


The zoophytes which constitute the class _Zoantharia_ are quite great
personages. Some of them are eighteen or twenty inches long; at the same
time, others scarcely exceed the eighth part of an inch in length. They
live in all seas, and seem to have existed through many ages of the
earth's history; they appear at an early geological period, and they
have performed an important part in its formation; we shall see that,
with great numbers of them, parts cut off from their bodies continue to
live and become new individuals.

The name of _Zoantharia_ was first given to the class by Gray; but here
we give it a somewhat wider signification, embracing under it the
madrepores and starred stones of Lasueur, who is reminded of a field
enamelled with small flowers when he sees the little polyp of _Porites
Astroïdes_ in full blow. "But it is only," says Johnston, "when they lie
with their upper disk expanded, and their tentacula displayed, that they
solicit comparison with the boasts of Flora; for, when contracted, the
polyp of the madrepores conceal themselves in their calcareous cups, and
the actiniæ hide their beauty, assuming the shape of an obtuse cone or
hemisphere of a fleshy consistence, or elongating themselves into a sort
of flabby cylinder that indicates a state of relaxation and indolent
repose."

These zoophytes are flesh-eaters, and consume quantities truly
prodigious, of animals such as the crustaceans, worms, and small fishes.
They are all marine, nearly all attached to the same spot for life, and
they live in colonies. Some few are isolated and live by themselves,
either free or attached to the soil. They differ altogether from the
animals belonging to the _Alcyonaria_ by their disposal of, and mode of
multiplying, tentacula. These appendages in the _Zoantharia_ never
present the _bipinnate_ arrangement which is observable in the
_Alcyonaria_. They are habitually simple, and, if they present
ramifications, these are only exceptional. In nearly every instance, the
tentacles exist to the number of twelve, eighteen, twenty-four, and even
larger numbers, which form a sort of concentric crown to the animal.

_Zoantha thalassanthos_ (Lesson), which has given its name to the group,
consists of large turf-like tufts of coral attached to a rock. Its
animalcules are packed closely together, and their expanded flower-like
heads have a curious resemblance to a mass of flowers in full bloom.
They are borne on bending root-like stems of pure white, interlacing one
with the other, surmounted by a fusiform or spindle-shaped body,
pediculate and swelling towards the middle, but truncate at the summit,
of a reddish-brown colour, marked with longitudinal stripes more highly
coloured; its consistence is firm and parchment-like. From the body
issues a tube, narrow, muscular, contractile, and red in colour,
terminating at the summit in eight elongated arms or tentacula, of a
pure yellow, traversed by a nervure of the same colour. The edges of
these arms are fringed with fine pinnæ, parallel to each other, of a
bright maroon colour, and resembling the barbs of a feather. According
to Lesson, the arms of this _Zoantha_ are kept unceasingly in motion,
which produces in the water small oscillating currents, in the course of
which the animalcules on which the polyps feed are precipitated into the
stream leading to their mouths.

The tendency to produce a calcareous polypidom is a property almost
universal with animals of this class. Zoologists are agreed in dividing
them into three very distinct orders--namely, the ANTIPATHIDÆ,
consisting of the genera _Antipathes_, _Cirripathes_, and _Seipathes_,
in which the polypidom is of a horny consistence; the MADREPORIDÆ, in
which the polypidom is calcareous and stony; finally, the ACTINIDÆ,
which produce no polypidom.


ANTIPATHIDÆ.

We need not dwell upon this group, which is comparatively uninteresting.
They correspond with the family of _Gorgonidæ_ among the _Alcyonaria_,
which they resemble in having the central axes branching after the
manner of a shrub; but the polyps have the mouth surrounded with a crown
of six simple tentacula. The axis is of a harder and denser tissue than
that of the Gorgons, and presents on its surface small spiniform
projections. The polypiferous crust, with which they are covered, is in
general very arenaceous, and is so easily detached, that it is rare to
see in collections anything but the denuded skeleton of the colony. In
_A. arborea_, the polypidom is fragile and brittle; when dry, the
branches, always slender and delicate, resemble the barbs of a feather.
The colour is of a deep black, or rather bistre and _terra de sienna_
tint. Under a powerful lens, the extremities of the branches appear to
be covered with small spines, and the trunk is formed of oval and
irregular concentric beds, which are the zones of growth. Its
consistence is firm, so that it can be worked up and converted into
chaplets for pearls and other bijouterie: it is known in commerce as
_black coral_.


MADREPORIDÆ.

The _Madrepora_ are better known than their congeners. They are
sometimes, but erroneously, designated corals, since the coral forms no
part of this group.

The Madrepores are remarkable for the calcareous crust which always
surrounds their tissue, and determines the formation of their polypidom.
They are in other respects easily recognized by the star-like structure
of their polypidom, in which may always be distinguished a visceral
chamber, the circumference of which is furnished with perpendicular
laminæ or partitions, which are always directed towards the axis of the
body. When sufficiently developed they constitute, by their assemblage,
a star-like body formed of a great number of rays. The polypidom is
always calcareous. The consolidation of the envelope of each polyp
produces at first a kind of sheath, to which Milne Edwards has given the
name of the wall. The partitions which proceed from the interior towards
the axis of the visceral chamber occupy the subtentacular cells; the
terminal and open portion designated the calyx is in organic continuity
with the polyp, which has retired thither more or less completely as
into a cell.

Milne Edwards remarks that the polypidom of the _Madrepora_ present in
their structure five principal modifications, due in part to the
fundamental number of which the chambered cells are the multiple, and in
part to the mode of division in the visceral chamber, and finally to the
manner in which its tissue is constituted. M. Edwards avails himself of
this peculiarity of structure in order to divide the Madrepores into
fixed sections; namely, _Madrépores apores_, _Madrépores perforés_,
_Madrépores tabulés_, _Madrépores tuberleux_, and _Madrépores rugueux_.
In the group of Aporous Madrepores, the polypidom is perhaps the most
highly organized. We find there a well-developed and very perfect wall,
and a well-developed visceral apparatus. The calyx is neatly starred;
the number of rays in the earlier stages being six, which soon
afterwards reach from twelve to twenty-four. The cells between the
chambers are sometimes open in all their depth, sometimes more or less
shut up by transverse plates; these, being independent of each other,
are never reunited in the breadth of the visceral cavity, so that they
constitute discoid plates such as we find in _tabular_ and _rugose_
Madrepores.

The animals belonging to this group, which may be characterised as
_stelliform_ or star-like, are very abundant in every sea, and in
several geological formations. They constitute many families, among
which may be noted the MILLEPORINA of Ehrenberg, the polypidom of which
Dr. Johnston describes as "calcareous, fixed, plant-like, branching or
lobed, with cells scattered over the whole surface, distinct, sunk in
little fosses, obscurely stellate, the lamellæ narrow and almost
obsolete." (JOHNSTON'S _Zoophytes_, vol. i. p. 194.) In _Turbinolia_,
the animal is simple, conical, striped, furrowed externally with larger
and smaller ribs, the mouth surrounded by numerous tentacula, and
solidified by a calcareous polypidom, which is free, conical, and also
furrowed externally; attenuated at the base, but enlarged at the summit,
and terminating in a shallow radiated lamellar cup or cell. Several
species have been dredged off the coast of Cornwall, and the west coast
of Scotland and Ireland.

_T. melletiana_ is described as coral-white, wedge-shaped, somewhat
compressed, with interspaces or ribs equidistant, smooth, and glossy.
Above, the ribs turn over the edge, and are continued into the centre of
the enlarged cup, forming its lamellæ. "That the zoophyte must have
lived for some time after having become a movable thing, is proved,"
says Dr. Johnston, "by the ribs being continued beyond or round the
point of attachment." The specimen here described was dredged alive, and
Professor Forbes says of it that "it is a most interesting and beautiful
species, the more so as it is certainly identical with Defrance's
_Turbinolia melletiana_, found in both the crag formations."

[Illustration: Fig. 66. Caryophillia cyathus (Lamarck).]

The _Caryophilliæ_ (Lamarck), from καρύα, a nut, and ϕύλλου,
a leaf, have the polypidom permanently fixed, simple, striated
longitudinally, and the summit hollowed into a lamellated star-like
cup; the animal, actinia-like, is provided with a simple, or double
crown of tentacula, projecting from the surface of star-like,
cylindrical, cone shaped cells. In _C. cyathus_ (Lamarck) (Fig. 66),
which inhabits the Mediterranean, the polyps are of a greyish colour,
the tentacula streaked with black. The polypidom is erect and upright,
sometimes cylindrical, and generally so firmly attached to the rock as
to seem a part of it. The lamellæ are of three kinds: one large and
prominent, between every pair of which there are three, sometimes five,
smaller ones, the centre one being divided into two portions forming
an inner series. The lamellæ are arched entire and striated on the
sides, whence the margin appears somewhat crenelated. "It is found,"
says Mr. Couch, "of all sizes, from a mere speck to an inch in height.
In a very young state, it is sometimes found parasitical on _Alcyonium
digitatum_, on shells, and on the stalks of sea-weeds; but as these
substances are very perishable, and offer no solid foundation, large
specimens are never found on them. In its young state the animal is
naked, and measures about the fifteenth of an inch in diameter, and
about the thirty-second of an inch in height. In the earliest state
in which I have seen the calcareous polypidom, there were four small
rays, which were free or unconnected down to the base; in others I
have noticed six primary rays, but in every case they were unconnected
with each other. Other rays soon make their appearance between those
first formed; they are mere calcareous specks at first, but afterwards
increase in size. The first union of rays is observed as a small
calcareous rim at the base of the polyp, which afterwards increases in
height and diameter with the age of the animal."

The animals of this interesting polypidom are vividly described by Dr.
Coldstream, in a communication to Dr. Johnston, as he observed them at
Torquay:--

"When the soft parts are fully expanded," he says, "the appearance of
the whole animal closely resembles an actinia. When shrunk, they are
almost entirely hid amongst the radiating plates. They are found
pendent," he adds, "from large boulders of sandstone, just at low-water
mark. Sometimes they are dredged from the middle of the bay. Their
colour varies considerably. I have seen the soft parts white, yellowish,
orange-brown, reddish, and of a fine apple-green. The tentacula are
usually paler."

The _Caryophilliæ_ are sometimes dredged from great depths; Professor
Travers dredged one in eighty fathoms, and Dr. Johnston remarks that the
existence of an animal so vividly coloured at so great a depth is worthy
of remark. "When taken," says the professor, "the animal was scarcely
visible, being contracted; when expanded, the disk was conspicuously
marked by two dentated circles of bright apple-green, the one marginal
and outside the tentacula, the other at some distance from the
transverse and linear mouth. In the dark, the animal gave out a few dull
flashes of phosphorescent light."

In addition, we may mention the assertion of Mr. Swainson, that _C.
ramea_, common in the Mediterranean, is occasionally found on the
Cornish coast; but Dr. Johnston thinks it improbable that it could have
escaped the attention of Mr. Couch and Mr. Peach, had it been so.

As belonging to this family, we present here illustrations of _Flabellum
pavoninum_, Lesson (Fig. 67).

[Illustration: Fig. 67. Flabellum pavoninum (Lesson).

    1. Vertical position.
    2. Upper edge, with its plates and median thread.
    3. Form of the animal.
]

Of the _Occulinæ_, the animal is unknown, but it is contained in regular
round radiated cells, more or less prominent, and scattered on the
surface of a solid, compact, fixed tree-like coral. The individuals
dispose themselves in ascending spiral lines, and appear to be regularly
dispersed on the surface of the several branches. The typical species,
_O. virginea_, formerly known as the White Coral, although it differs
widely in reality from the true Coral, both in its structure and by its
star-like polypiferous cells (Fig. 68), is found in the Mediterranean
and also in the equatorial seas. Over the specimen we see (2) a portion
of a branch magnified, in order that the reader may appreciate
numerically the form of polype over its cells.

[Illustration: Fig. 68. Occulina virginea (Lamarck).]

[Illustration: Fig. 69. Stylaster flabelliformis (Lamarck).]

The species formerly named _Occulina flabelliformis_, and which now
bears the name of _Stylaster flabelliformis_, which is represented in
Fig. 69, will give an excellent idea of these arborescent zoophytes.
The polypidom is in the form of a fan, with many very unequal branches;
the larger branches are smooth, the middle-sized are covered with small
points. This fine zoophyte is found in the seas which surround the Isle
of Bourbon and the Mauritius, a fine example of which is to be seen in
the collection of the Museum of Natural History of Paris.


ASTRÆACEA.

How diversified are the forms of aquatic life! "Nature revels in these
diversities," to paraphrase the saying of one of the ancient kings of
France. Here are animals, the frame of which might have been designed by
a geometrician. They are called Star Corals (_Astrea_). Their
resemblance to the well-known figure was too striking to escape the
observation of naturalists; but the organization of these creatures of
the ocean is far from being rigorously regular, for Nature rarely
employs perfectly straight lines, giving an evident preference to
circles and waving lines.

[Illustration: Fig. 70. Astrea punctifera (Lamarck).]

The _Astrea_ are inhabitants of the Indian Ocean, where they are found
in a great variety of forms, which has led to their subdivision into
many genera by Messrs. Milne Edwards and J. Haime. The animals are
short, more or less cylindrical, with rounded mouth placed in the centre
of a disk, covered with a few rather short tentacula; the cells are
shallow, with radiating lamellæ in _Astrea punctifera_ (Fig. 70),
forming by their union a many-formed coral, which often encrusts other
bodies. In short, this polyp may be described as a parasite, for it
generally attaches to some other bodies, and it is by no means unusual
to meet with it attached even to shells.

[Illustration: Fig. 71. Meandrina cerebriformis (Lamarck).]

The _Meandrina_ differ from the _Astreas_ in having the surface hollowed
out into shallow sinuous elongated cells, furnished on each side of the
mesial line with hooked lamellæ, ending against one or other of the
ridges with separate valleys; the polypidom, which is calcareous, being
fixed, simple, and inversely conical when young, and globular when old.
The animals have each a distinct mouth, and lateral series of short
tentacula; they are contained in shallow cells, meeting at the base, and
forming by their union long and tortuous hollows. _Meandrina
cerebriformis_ (Fig. 71), so called from its resemblance to the folds of
the brain, is a native of the American Seas.

The _Fungia_, so called by Lamarck from their resemblance to the
vegetable Fungi, are too remarkable in their appearance to be passed
over in silence. The major part of the species only occur in recent
geological strata. Nevertheless some of the species were very numerous
in the Cretaceous period, and even find representatives in the Silurian
period; it is this group in which Madrepores of great size are found.

[Illustration: Fig. 72. Fungia echinata (Milne Edwards).]

The family, as we have already said, take their names from their
supposed resemblance to the Mushroom. "But," says Peyssonnel, "there is
this difference between terrestrial and marine mushrooms--that the
former have leaflets below, and those of the ocean have them above (Fig.
72). These leaflets are only expansions of the Madrepores. Now, although
I have not actually examined these petrified Mushrooms of the sea, I
have no reason to doubt but that they are true genera or species of
Madrepores, containing, like others, the zoophytes which form them. In
my travels in Egypt, in 1714 and 1715, I never heard it said that the
Nile could produce them." In this last remark, Peyssonnel makes allusion
to the opinion entertained by many ancient authors, that the Fungia were
productions of the Nile.

The animal is gelatinous or membranous, generally simple, depressed,
and oval, with mouth superior and transverse, in a large disk, which is
covered by many thick cirrhiform tentacula; the polypidom is rendered
solid internally by a calcareous solid deposit of a simple figure,
having a star of radiating, acutely-pointed lamellæ above, and simple
rays, full of wrinkles, beneath. There are nine species, mostly natives
of the Indian Seas, which De Blainville arranges in three groups,
according as they are simple and circular, simple and compressed, or
complex and oblong. In _Fungia echinata_, represented in Fig. 72, we
have a species which inhabits the Indian and Chinese Seas. It belongs to
the last group, being oblong in form, convex above, and concave below.
The hollow, from which the lamellæ or chamber-walls proceed, are of
considerable length; the toothed partitions are very irregular, thin and
prickly, resting upon their lower edge, in order to leave the concave
portion of the field free to a host of excrescences, resembling the roof
of a grotto studded with small stalactites.

[Illustration: Fig. 73. Fungia agariciformis (Lamarck).]

The conformation of the softer parts of this polypus has been described
by many travellers. The upper portion of the body of the animal,
corresponding to the lamelliform part of the polypus, is furnished with
scattered tentacula, very long in some species, and remarkably short in
others. These tentacula appear to terminate in a small sucker, and the
animal seems to recover its position with difficulty, when overturned.
In order to complete our description of these curious madrepores, we may
refer to _Fungia agariciformis_, represented in Fig. 73. This remarkable
species inhabits the Red Sea and the Indian Ocean, and is here
represented with its polyps.

       *       *       *       *       *

De Blainville gave the name of MADREPORÆA to the second group of his
stony _Zoantharia_, placing them after the _Madrephylliæ_. The products
of this section are generally arborescent, with small, partially
lamelliform cells, which are constantly porous in the interstices of the
walls of the cells, this being its most important characteristic. Thus
the visceral apparatus constitutes the essential part of the polypus,
presenting no side plates, the visceral chamber being open from the base
to the summit, and neither filled with dissepiments, pulpy matter, nor
with plates.

The history of these inhabitants of the deep is extremely obscure, and
will probably always remain so; the most beautiful of their productions
are intertropical, and consequently beyond the reach of discriminating
observers during the life of the animal. Solander proposed to divide the
genus according to certain characteristics in the growth of the coral,
and De Blainville has rearranged the groups formed by Lamarck,
Lamouroux, and Goldfuss, with special reference to the soft parts of the
animals figured by Lesueur, Quoy, Gaimard, and others, who have observed
them in their native state.

The perforated _Zoantharia_ form three very natural families: the
_Eupsammidæ_, the _Madreporidæ_, and the _Poritidæ_. The first have the
solid parts of the polyps, simple or complex, with well-developed
lamellar portions, the central column spongious, walls granular,
semi-ribbed, and perforated. The second are composite, increasing by
gemmation; walls spongy and porous; septa lamellous, and well developed.
In the third the visceral chambers are divided into two equal parts by
the principal septa, which are more developed than the others, meeting
by their inner edge. The _Dendrophylliæ_ (Fig. 74) are conspicuous among
the _Eupsammidæ_.

We shall describe three genera, the two first of which belong to the
MADREPORÆA, and the last of the family of the _Porides_.

[Illustration: Fig. 74. Dendrophyllia ramea, half natural size (De
Blainville).]

_Dendrophyllia ramea_, represented in Figs. 75 and 76, is an elegant
madrepore of the Mediterranean. Its polyp presents a very large trunk
charged with short ascending branches; it usually attains to about a
yard and a half in height. The polyps are provided with a great number
of tentacula, in the centre of which the mouth is placed. They are
deeply buried in the cells, which radiate from numerous unequally
_saillant_ plates. Peyssonnel, who had seen the polyps of this colony,
says: "I may observe that the extremities or summits of the branching
madrepore, the species in question, which in the Provencal we call
Sea-fennel, is soft and tender, filled with a glutinous and transparent
mucous thread, similar to that which the snail leaves on its path.
These extremities are of a fine yellow colour, five or six lines in
diameter; soft, and more than a finger's breadth in length. I have seen
the animal nestling in them; it seemed to be a species of cuttle-fish or
sea-nettle. The body of this sea-nettle must have filled the centre; the
head being in the middle, surrounded by many feet or claws, like those
of the cuttle-fish. The flesh of this animal is very delicate, and is
easily reduced to the form of a paste, melting almost under the touch."

[Illustration: Fig. 75. Dendrophyllia ramea (De Blainville). Natural
size, with polypi.]

[Illustration: Fig. 76. A part magnified.]

The madrepores abound in all intertropical seas, taking a considerable
part in the constitution of the reefs which form the coral and
madreporic islands so conspicuous in the ocean. The tree-like
_Dendrophyllia_ (_D. ramea_, Figs. 75 and 76) have cells of considerable
depth, radiating into numerous lamellæ, forming a widely-branching
arborescent coral, externally striated, internally furrowed, and
truncate at the extremities. The animals are actiniform, furnished with
numerous cleft tentacula, in the centre of which is the polygonal mouth.
In the _Lobophyllia_, the tentacula are cylindrical, the cells conical,
sometimes elongated and sinuous, with a sub-circular opening terminating
the few branches of the polyp, which is fixed, turbinate, and striated.
The Plantain Madrepore, _M. plantaginea_ (Lamarck), is an interesting
example, the polyp presenting itself, as in Fig. 77, in tufts, with
slender and prolific branches.

[Illustration: Fig. 77. Madrepora plantaginea (Lamarck).]

In _Madrepora palmata_, vulgarly named Neptune's Car, we have a large
and beautiful species, whose expanding branches are flat, round at the
base, and forming in lobes, whose length is often as much as three feet
high, with a breadth of twenty inches, and a thickness of two to two and
a half: this fine madrepore is found in the Caribbean Sea and among the
Antilles.


PORITES.

The Porites are madrepores produced by a pitcher-shaped fleshy animal,
with twelve short tentacula; the cells are unequally polygonal,
imperfectly defined, slightly radiating by thread-like pointed rays,
with prickles placed at intervals. The polypus is polymorphous or
many-formed, composed of a reticulated and porous tissue, the
individuals forming it being always completely united together.
Externally it presents the figure of an irregular trellis-work, more or
less loosely connected in its meshes. As a type of this organization, we
give a figure of the Forked Porites (_P. furcata_, Fig. 78), of the
natural size. The branches are generally dichotomous, that is, rising in
pairs obtusely lobed. In some of the species the rays are more fully
marked, and resemble a bed of miniature anemones thickly crowded
together, as in _Gonispora columna_, in which the polypi have a central
mouth, round which the twelve short tentacula radiate; the coral is
stony, fixed, branched, or lobed, having a free surface covered with a
great number of regular stars, which are highly characteristic, and
cannot be confounded with those of an astrea or madrepore.

[Illustration: Fig. 78. Porites furcata (Lamarck), natural size.]

[Illustration: Fig. 79. Millepora alcicornis (Linn.), one-fourth natural
size.]

In the Tabulate Madreporides, the polyp is essentially composed of a
highly-developed mural system. The visceral chambers are divided into a
series of stages or stories, by perfect diaphragms or plates placed
transversely, the plates depending from the walls and forming perfect
horizontal divisions, extending from one wall of the general cavity to
the other. In order that the reader may form some idea of the Tabulate
Madrepores, one of the polyps known as _millepores_ is here represented.
The millepores were first separated from the madrepores by Linnæus,
along with a great number of species distinguished by the minuteness of
their pores or polypiferous cells (Fig. 79), represented above, as
nearly allied, and perhaps identical with Dr. Johnston's _Cellepora
cervicornis_, a species found in deep water on the Devonshire and
Cornwall coasts, and, indeed, all round our west coast. "A single
specimen of this millepore is about three inches in height," says Dr.
Johnston, "and somewhat more in breadth. It rises from a broad flattened
base, and begins immediately to expand and divide into kneed branches or
broad segments, many of which anastomose, so as to form arches and
imperfect circles. The extreme segments are dilated and variously cut,
sometimes truncate, both sides being perforated with numerous pores just
visible to the naked eye, and arranged in rows; the pores circular, and
level with the surface on the smooth and newly-formed parts; but in the
older parts they form apertures of urceolate cells, which appear to be
formed over the primary layer of cells, giving to the surface a roughish
or angular appearance. The orifice is simple, contracted, with a very
small denticle on one side; the thickness of the branches varies from
one half to two lines; the interior is cellular; the new parts are
formed of two layers of horizontal cells, but the older parts are
thickened by cells superimposed on the primary layers."

_Millepora moniliformis_ is a species which attaches itself to the
branches of the gorgons, and forms there a series of little rounded or
lateral lobes. The animal is unknown, the cells very small, unequal,
completely immersed, obsoletely radiate and scattered; the polypier
fixed, cellular within, finely porous and reticulated externally,
extending into a palmated form.

Of tuberous or wrinkled madrepores, which consist almost entirely of
fossil species chiefly belonging to the Silurian formation, we shall
only note _Cyathophyllum_ as one of the best known species.

       *       *       *       *       *

There is no spectacle in Nature more extraordinary, or more worthy of
our admiration, than that now under consideration. These zoophytes,
whose history we are about to investigate--wretched beings gifted with a
half-latent life only--these animalcules so small and so fragile--labour
silently and incessantly in the bosom of the ocean, and, as they exist
in innumerable aggregated masses, their cells and solid axes finish by
producing in the end enormous stony masses. These calcareous deposits
increase and multiply with such incalculable rapidity, that they not
only cover the submarine rocks as with a carpet, but they finish by
forming reefs, and even entire islands, which rise above the surface of
the ocean in a manner remarkable at once for their form and the
regularity with which they repeat themselves.

In noting the Indian and Pacific Oceans, navigators had long been struck
with the appearance of certain earthy bases, which presented a
conformation altogether singular. In 1601, Pyrard de Laval, speaking of
the Malouine (now the Falkland) Islands, said: "They are divided into
thirteen provinces, named _atollons_, which is so far a natural division
in that place, that each atollon is separated from the other, and
contains a great number of smaller islands. It is a marvel to see each
of these atollons surrounded on all sides by a great bank of
stone--walls such as no human hands could build on the space of earth
allotted to them. These atollons are almost round, or rather oval, being
each about thirty leagues in circumference, some a little less, others a
little more, and all ranging from north to south, without any one
touching the other. There is between them sea channels, one broad, the
other narrow. Being in the middle of an atollon, you see all around you
this great stone bank, which surrounds and protects the island from the
waves; but it is a formidable attempt, even for the boldest, to approach
the bank and watch the waves as they roll in and break with fury upon
the shore."

Since the publication of Laval's description, many circular isles, or
groups of islands, analogous to these atollons, since called _atolls_,
have been discovered in the Pacific Ocean and other seas. The naturalist
Forster, who accompanied Cook in his voyage round the world, first made
known the more remarkable characteristics of these gigantic formations.
He perfectly comprehended their origin, which he was the first to
attribute to the development of the calcareous zoophytic polypier.

After Forster, many other naturalists--Lamouroux, Chamisso, Quoy,
Gaimard, Ehrenberg, Ellis, Darwin, Couthony, and Dana--have furnished
Science with many precious lessons on the natural history of coral
islands and madreporic reefs. We can only glance at a few of the more
remarkable genera of these interesting creatures.

"Those occupying the same Coral," says Frédol, "live in perfect harmony;
they constitute a family of brothers, physically united in the closest
bonds of union. They occupy the same dwelling, each having its separate
chamber; but the power of abandoning it is denied them. Attached each to
its cell, they are driven to trust in Providence for the food which
never fails them; moreover, what is eaten by each mouth profits the
whole community. Urged on by a wonderful instinct, the polypes labour
together at the same work; isolated, they would be weak and helpless; in
combination, they are strong." M. Lacaze-Duthiers has even demonstrated
that _Antipathes glaberrima_, _Gorgonia tuberculata_ (Lamarck),
_Leiopathes glaberrima_ (Gray), and _Leiopathes Lamarckii_ (Haime),
were present on the same coral, the _Gerardia_ of Lamarck. It is thus
recognized that, under the general denomination of polyps, very distinct
genera are found, some being of the _Hydra_ type, others belonging to
the _Plumularia_. The first are very common on our coast: they include
the _Tubularia_, the _Campanularia_, and the _Sertularia_.

The Reed Tubularia (_T. indivisa_) is remarkably curious: its numerous
stems are horny, yellow, and marked at intervals with irregular knots,
resembling the joints of a straw. Their lower extremity is tortuous, and
apt to adhere to foreign bodies; the upper part is nearly upright, and
slightly flexuous, the whole resembling some flowering plant, without
leaves or lateral branches. The _Campanularias_ are altogether
different; the end of the branches whence the polyps issue are broad and
bell-shaped, _C. dichotoma_ presenting a stem of brownish colour, thin
as a silken thread, but strong and elastic. The polyps are numerous, a
branch eight inches in height being inhabited by as many as twelve
hundred individuals.

The _Sertularias_ have a horny stem, sometimes simple, sometimes
branching, and may easily be mistaken for small plants. Their name is
derived from the Latin _sertum_, a bouquet; and, indeed, they can only
be described as trees in miniature, with branches yellow and
semi-transparent, each tree having seven, eight, twelve, or twenty small
panicles, each of which will contain about five hundred animals, the
tree itself containing probably an association of ten thousand.
Occasionally _Sertularia argentea_ is said to afford shelter and
employment for a hundred thousand of these creatures. _S. falcata_,
having all the grace and elegance of the delicate and slender Mimosa, is
now placed among the Bryozoares.

The minute cells in which the polyps are lodged are not always arranged
in the same manner. Sometimes the cells occupy one side only; in other
instances they occupy both; sometimes they are grouped like the pipes of
an organ, at others they are ranged spirally round the stem, or arranged
at intervals, forming horizontal rings round it.

The _Alcyonaria_ are very common on some parts of our coast, where
scarcely a stone or shell is dredged up that does not support one or
more specimens known to the fishermen as "cow's paps," "dead men's
fingers," and other popular names. This round and lobed fleshy mass is
quite a colony in itself; placed in pure sea water, it very soon
presents certain yellow or grass-like points, which gradually expand and
display themselves in their native transparent and animated coralline.
Each of these polyps have eight dentate petals, in the centre of which
is the mouth; the body of the polyp is tubular, varying externally in
length, traversed internally throughout its entire mass by a tissue
studded with reddish spiculæ, and furrowed with small reed-like ribbons,
common to all the individuals of the association.

Among the _Tubiporidæ_ may be noted _Tubipora musica_ (Linnæus), from
the Indian Ocean, characterised by its stony tubes, simple, numerous,
straight or flexible, parallel, and slightly radiating, of a fine
purple, and united together at intervals by transverse bands, so as to
resemble the pipes of an organ. The polyp is a brilliant grass green,
according to Péron; the tentacula furnished on each side with two or
three rows of granulous fleshy papillæ, to the number of sixty to eighty
(Lesson).

The _Gorgonia_ is studded with calcareous or siliceous spiculæ which
form a crust in drying. This crust is friable, and frequently preserves
the colours more or less brilliant which characterise it. Their cells
are sometimes hollowed out of the plain surface; sometimes they occur in
the projecting mammals; these are smooth, rough, or scaly--sometimes
pendent the one from the other.

These animals attach themselves to solid bodies, sometimes even to each
other, grafting themselves or interlacing each other in all directions.
In colour they are whitish, pure white, yellow, and apple-green; their
shades, passing from olive-brown to deep blue, from vermilion to violet,
and from pale yellow to pearly-grey. Each tube or cell contains an
individual. The cells are more or less deep, according to the species.
The polyps are composed generally of a hidden portion more or less
tubular, and of a star-like portion more or less displayed. This latter
portion presents from eight to twelve soft and granulous wattles,
susceptible of expansion, like the petals of a flower. When these
appendages are displayed, they often attain twice the height of the
body; in this state they are nearly transparent, except towards the
extremity. They extend or compress these wattles, dilate or contract the
mouth according to their wants; but their digestive tube is firmly
soldered to the cell, while the axis which supports the cells is
motionless. What a singular combination is here presented! Trees,
one-half of which are animated, growing at the bottom of the sea;
polyps, one-half of which is imprisoned, and riveted to their person;
their stomachs in the bark, their arms on a branch, their movements
perfect repose!

[Illustration: Plate IV.--Coral Island of Clermont-Tonnerre, in the
Pomotouan Archipelago.]

These minute silent workers are active and indefatigable; their task is
to separate the salt and other chemical particles from the waters of the
ocean, and, while feeding themselves, secrete and organise the axis
which bears their lodging. They love the warmer regions of the ocean; in
colder regions, the results of their labours are extremely limited: the
one forms a sward of submarine life, which carpets the rocks; the other
produces animated stalactites, great shrubs, whole forests of small
trees. The electric cable which unites Sardinia to the Genoese fort was
so encrusted with corals and bryozoares, that certain portions taken
from the water for repairs had attained the size of a small barrel.

       *       *       *       *       *

The atolls present three unfailing and constant peculiarities. Sometimes
they constitute a great circular chain, the centre of which is occupied
by a deep basin, in direct communication with the exterior sea, through
one or many breaches of great depth. These are the _atolls_, described
more than two centuries ago by Pyrard de Laval; sometimes they surround,
but at some distance, a small island, in such a manner as to constitute
a sort of skeleton or girdle of reefs; finally they may form the
immediate edging or border of an island or continent. In this last case
they are called fringing littorals, or edging reefs. At the distance of
a few hundred yards only from the edge of some of these reefs, the sea
is of such a depth that the sounding-lead has failed to reach the
bottom.

In order to give an idea of the general form of these atolls, although
they are rarely so regular, the reader is referred to PL. III., which
represents one of these islands of the Pomotouan Archipelago, in the
Indian Ocean. It represents the island of Clermont-Tonnerre, figured by
Captain Wilkes in the American Exploring Expedition. The exterior girdle
of rocks here surrounds a basin nearly circular. Such is the general
form--the typical form, so to speak--of the coral isles, of which this
is a fair representation.

The zoophytes which form these mineral accumulations belong to diverse
groups, and nowhere have the results of observations made upon these
atolls been more minutely described than in Mr. Darwin's remarks on the
grand Cocos Island situated to the south of Sumatra, in the Indian
Ocean.

No writer, it seems to us, has reasoned on these atolls more
comprehensively than the author of the "Origin of Species." "The earlier
voyagers," he says, "fancied that the coral-building animals
instinctively built up their great corals to afford themselves
protection in the inner parts; but so far is this from the truth, that
those massive kinds, to whose growth on the exposed outer shores the
very existence of the reef depends, cannot live within the lagoon, where
other delicately-branching kinds flourish. Moreover, in this view, many
species of distinct genera and families are supposed to combine for one
end; and of such a combination not a single instance can be found in the
whole of nature. The theory that has been most generally received is,
that atolls are based on submarine craters, but when the form and size
of some of them are considered, this idea loses its plausible character.
Thus, the Suadiva atoll is forty-four geographical miles in diameter in
one line by thirty-four in another; Rimsky is fifty-four by twenty miles
across; Bow atoll is thirty miles long, and, on an average, six miles
broad. This theory, moreover, is totally inapplicable to the Northern
Maldivian atolls in the Indian Ocean, one of which is eighty-eight miles
in length, and between ten and twenty in breadth."

The various theories which had been propounded failing to explain the
existence of the coral islands, Mr. Darwin was led to reconsider the
whole subject. Numerous soundings taken all round the Cocos atoll showed
that at ten fathoms the prepared tallow in the hollow of the sounding
rod came up perfectly clean, and marked with the impression of living
polyps. As the depth increased, these impressions became less numerous,
but adhering particles of sand succeed, until it was evident that the
bottom consisted of smooth sand. From these observations, it was obvious
to him that the utmost depth at which the coral polyps can construct
reefs is between twenty and thirty fathoms. Now, there are enormous
areas in the Indian Ocean in which every island is a coral formation
raised to the height to which the waves can throw up fragments and the
winds pile up sand; and the only theory which seems to account for all
the circumstances embraced, is that of the subsidence of vast regions in
this ocean. "As mountain after mountain and island after island slowly
sunk beneath the water," he says, "fresh bases would be successively
afforded for the growth of the corals. I venture to defy any one to
explain in any other manner how it is possible that numerous islands
should be distributed throughout vast areas, all the islands being low,
all built of coral absolutely requiring a foundation within a limited
depth below the surface."

The _Porites_, according to Mr. Darwin, form the most elevated deposits
of those which are situated nearer the level of the water: _Millepora
complanata_ also enters into the formation of the upper banks. Various
other branched corals present themselves in great numbers in the
cavities left by the _Porites_ and _Millepora_ crossing each other. It
is difficult to identify species occupying themselves in the deeper
parts, but, according to Darwin, the lower parts of the reefs are
occupied by polyps of the same species as in the upper parts; at the
depth of eighteen fathoms and upwards, the bottom consists alternately
of sand and corals. The total breadth of the circular reef or ring which
constitutes the atoll of the Keeling or Cocos Island varies from two
hundred to five hundred yards in breadth. Some little parasitic isles
form themselves upon the reefs, at two or three hundred yards from their
exterior edge, by the accumulation of the fragments thrown up here
during great storms. They rise from two to three yards above the sea
level, and consist of shells, corals, and sea urchins, the whole
consolidated into hard and solid rock.

Mr. Darwin's description of a kind of Sea-pen, _Virgularia Patagonia_,
throws some curious light on the habits of these creatures. "This
zoophyte consists of a thin, straight, fleshy stem, with alternate rows
of polypi on each side, and surrounding an elastic stony axis, varying
in length from eight inches to two feet. The stem at one extremity is
truncate, but at the other is terminated by a vermiform fleshy
appendage. The stony axis, which gives strength to the stem, may be
traced at the extremity into a mere vessel filled with granular matter.
At low water, hundreds of these zoophytes might be seen projecting like
stubble, with the truncate end upwards, a few inches above the surface
of the muddy sand. When touched or pulled, they suddenly drew themselves
in with force, so as nearly, or quite, to disappear. By this action, the
highly elastic axis must be bent at the lower extremity, where it is
naturally slightly curved; and I imagine it is by this elasticity alone
that the zoophyte is enabled to rise again through the mud. Each polyp,
though closely united to its brethren, has a distinct mouth, body, and
tentacula. Of these polyps, in a large specimen there must be many
thousands, yet we see that they act by one movement. They have also one
central axis connected with a system of obscure circulation, and the ova
are produced in an organ distinct from the separate individuals. For,"
adds Mr. Darwin, in a note, "the cavities leading from the fleshy
compartments of the extremity were filled with a yellow pulpy matter
which, under a microscope, consisted of rounded semi-transparent grains
aggregated together into particles of various sizes. All such particles,
as well as separate grains, possessed the power of rapid motion,
generally revolving round different axes, but sometimes progressive."

The description of the Island of Cocos or Keeling is as follows:--"The
ring-formed reef of the lagoon island is surmounted, in the greater part
of its length, by linear islets. On the northern, or leeward side, there
is an opening through which vessels can pass to the anchorage within. On
entering, the scene was very curious, and rather pretty; its beauty,
however, entirely depended on the brilliancy of the surrounding colours.
The shallow, clear, and still water of the lagoon, resting in its
greater part on white sand, is, when illumined by a vertical sun, of the
most vivid green. This brilliant expanse, several miles in width, is on
all sides divided, either by a line of snow-white breakers from the dark
heaving waters of the ocean, or from the blue vault of heaven by the
strips of land crowned by the level tops of the cocoa-nut tree. As a
white cloud here and there affords a pleasing contrast to the azure sky,
so in the lagoon bands of living coral darken the emerald-green water.

"The next morning I went ashore on Direction Island. The strip of dry
land is only a few hundred yards in width; on the lagoon side there was
a white calcareous beach, the radiation from which, under this sultry
climate, was very oppressive. On the outer coast, a solid broad flat of
coral rock served to break the violence of the open sea. Excepting near
the lagoon, where there is some sand, the land is entirely composed of
rounded fragments of coral. In such a loose, dry, stony soil, the
climate of the intertropical regions alone could produce so vigorous a
vegetation. On some of the smaller islets, nothing could be more elegant
than the manner in which the young and full-grown cocoa-nut trees,
without destroying each other's symmetry, were mingled into one wood. A
beach of glittering white sand formed a border to those fairy spots.

"The natural history of these islands, from its very paucity, possesses
peculiar interest. The cocoa-nut tree, at the first glance, seems to
compose the whole wood; there are, however, five or six other trees. One
of these grows to a very large size, but, from the extreme softness of
its wood, it is useless; another sort affords excellent timber for
shipbuilding. Besides the trees, the number of plants is exceedingly
limited, and consist of insignificant weeds. In my collection, which
includes, I believe, nearly the perfect Flora, there are twenty species,
without reckoning a moss, lichen, and fungus. To this number two trees
must be added, one of which was not in flower, and the other I only
heard of. The latter is a solitary tree of its kind, and grows near the
beach, where, without doubt, the one seed was thrown up by the waves.

"The next day I employed myself in examining the very interesting yet
simple structure and origin of these islands. The water being unusually
smooth, I waded over the flat of dead rock as far as the living mounds
of coral, on which the swell of the open sea breaks. In some of the
gulleys and hollows there were beautiful green and other coloured
fishes, and the forms and tints of many of the zoophytes were admirable.
It is excusable to grow enthusiastic over the infinite number of organic
beings with which the sea of the Tropics, so prodigal of life, teems;
yet I must confess, I think those naturalists who have described in
well-known words the submarine grottoes, decked with a thousand
beauties, have indulged in rather exuberant language.

"I accompanied Captain Fitzroy to an island at the head of the lagoon;
the channel was exceedingly intricate, winding through fields of
delicately-branched corals. At the head of the lagoon we crossed a
narrow islet, and found a great surf breaking on the windward coast. I
can hardly explain the reason, but there is, to my mind, much grandeur
in the view of the outer shores of these lagoon islands. There is a
simplicity in the barrier-like beach, the margin of green bushes and
tall cocoa-nuts, the solid flat of dead coral-rock, strewed here and
there with great loose fragments, and the line of furious breakers, all
rounding away towards either hand. The ocean, throwing its waters over
the broad reef, appears an invincible, all-powerful enemy; yet we see it
resisted and even conquered by means which at first seem most weak and
inefficient. It is not that the ocean spares the rock of coral; the
great fragments scattered over the reef, and heaped on the beach whence
the tall cocoa-nut springs, plainly bespeak the unrelenting power of the
waves. Nor are any periods of repose granted; the long swell caused by
the gentle but steady action of the trade-winds, always blowing in one
direction over a wide area, causes breakers almost equalling in force
those during a gale of wind in the temperate regions, and which never
cease to rage. It is impossible to behold these waves without feeling a
conviction that an island, though built of the hardest rocks--let it be
porphyry, granite, or quartz--would ultimately yield and be demolished
by such an irresistible power. Yet these low, insignificant coral islets
stand, and are victorious; for here another power, as an antagonist,
takes part in the contest. The organic forces separate the atoms of
carbonate of lime, one by one, from the foaming breakers, and unite them
into a symmetrical structure. Let the hurricane tear up its thousand
huge fragments, yet what will that tell against the accumulated labour
of myriads of architects at work night and day, month after month? Thus
do we see the soft and gelatinous body of a polyp, through the agency of
the vital laws, conquering the great mechanical power of the waves of an
ocean which neither the art of man nor the inanimate works of Nature
could successfully resist."

       *       *       *       *       *

We have said that madreporic or coralline formations affect three forms,
to which the names of _atolls_, _barrier reefs_, and _fringing reefs_
have been applied. We have spoken of atolls; we shall now say a few
words on barrier and fringing reefs.

Barrier reefs are formations which surround the ordinary islands, or
stretch along their banks. They have the form and general structure of
atolls. Like atolls, the barrier reefs appear placed on the edge of a
marine precipice. They rise on the edge of a plateau which looks down on
a bottomless sea. On the coast of New Caledonia, only two lengths of his
ship from the reef, Captain Kent found no bottom in a hundred and fifty
fathoms. This was verified at Gambier Island in the Pacific Ocean, in
Qualem Island, and at many others.

According to Mr. Darwin, the barrier reef situated on the western coast
of New Caledonia is four hundred miles long; that along the eastern
coast of Australia extends almost without interruption for a thousand
miles, ranging from twenty or thirty to fifty or sixty miles from the
coast. As to the elevation of the islands thus surrounded with reefs,
it varies considerably. The Isle of Tahiti rises six thousand eight
hundred feet above the level of the sea; the Isle of Maurua to six
hundred; Aituaki to three hundred; and Manonai to about fifty feet only.

Around the Isle of Gambier the reef has a thickness of a thousand and
sixty feet, at Tahiti of two hundred and thirty. Round the Fiji Islands
it is from two to three thousand.

       *       *       *       *       *

The _fringing reefs_ immediately surrounding the island, or a portion of
it, might be confounded with the barrier reefs we have been describing,
if they only differed in their smaller breadth; but the circumstance
that they abut immediately on the coast in place of being separated by a
channel or lagoon more or less deep and continuous, proves that they are
in direct communication with the slope of the submarine soil, and
permits of their being distinguished from the barrier reefs. The
dangerous breakers which surround the Mauritius are a striking example
of the fringing reef. This island is almost entirely surrounded by a
barrier of these rocks, the breadth of which varies from a hundred and
fifty to three hundred and thirty feet; their rugged and abrupt surface
is worn almost smooth, and is rarely uncovered at low water. Analogous
reefs surround the Isle of Bourbon; all round this island the polyps
construct on the volcanic bottom of the sea detached mammalons, which
rise from a fathom to a fathom and a half above the water.

Madreporic coasting reefs present themselves also on the eastern coast
of Africa and of Brazil. In the Red Sea, reefs of corals exist which may
be ranked among the madreporic coasting reefs, in consequence of the
limited breadth of the gulf. Ehrenberg and Hemprich examined a hundred
and fifty stations in the Red Sea, all of which had outlying fringing
reefs of this description.

       *       *       *       *       *

It may be asked, With what rapidity are these coral and madreporic banks
formed, so as to become _atolls_ and _fringing reefs_? To answer this
question even approximately is very difficult. On the coast of the
Mauritius, according to M. d'Archaic,[6] the learned professor of the
Jardin des Plantes, the edge of the reef is produced by _Madrepora
corymbosa_, _M. pocillifera_, and two species of _Astrea_, which pursue
their operations at the depth of from eight to fifteen fathoms. At the
base is a bank of _Seriatopora_, from fifteen to twenty fathoms in
height. At the bottom, the sand is covered with _Seriatopora_. At twenty
fathoms we also meet with fragments of _Madrepora_. Between twenty and
forty fathoms the bottom is sandy, and the sounding-rod brings up great
fragments of _Caryophylla_. According to MM. Quoy and Gaimard, the
_Astreas_, which, as these naturalists consider, constitute the greater
part of the reefs, cannot live beyond four or five fathoms deep.
_Millepora alcicornis_ extends from the surface to the depth of twelve
fathoms; the _Madrepores_ and _Seriatopores_ down to twenty fathoms.
Considerable masses of _Meandrina_ have been observed at sixteen
fathoms; and a _Caryophylla_ has been brought up from eighty fathoms in
thirty-three degrees south latitude. Among the polyps which do not form
solid reefs, Mr. Darwin mentions _Cellaria_, found at a hundred and
ninety fathoms deep, _Gorgonia_ at a hundred and sixty, _Corallines_ at
a hundred, _Millepora_ at from thirty to forty-five, _Sertularias_ at
forty, and _Tubulipora_ at ninety-five fathoms.

According to Dana, none of the species which form reefs--namely,
_Madrepora_, _Millepora_, _Porites_, _Astreas_, and _Meandrineas_--can
live at a greater depth than eighteen fathoms. It is only near the
surface of the water that the zoophytes which produce minerals and form
madreporic banks put forth their powers; the points most exposed to the
beating of the waves is that which is most favourable to their growth;
it is there that the _Astreas_, _Porites_, and _Millepores_ most abound.

The proportionate increase of the structures, according to Mr. Darwin,
depends at once upon the species which construct the reefs and upon
various accessary circumstances. The ordinary rate of increase of the
madrepores, according to Dana, is about an inch and a half annually;
and, as their branches are much scattered, this will not exceed half an
inch in thickness of the whole surface covered by the madrepore. Again,
in consequence of their porosity, this quantity will be reduced to
three-eighths of an inch of compact matter. It is, besides, to be noted
that great spaces are wanting; the sands filling up the destroyed part
of the polyp are washed out by the currents in the great depths where
there are no living corals, and the surface occupied by them is reduced
to a sixth of the whole coralline region, which reduces the preceding
three-eighths to one-sixth. The shells and other organic débris will
probably represent a fourth of the total produce in relation to corals.
In this manner, taking everything into account, the mean increase of a
reef cannot exceed the eighth of an inch annually. According to this
calculation, some reefs which are not less than two thousand feet thick
would require for their formation a hundred and ninety-two thousand
years.

It is necessary to add, however, that in favourable circumstances the
increase of the masses of coral may be much more rapid. Mr. Darwin
speaks of a ship which, having been wrecked in the Persian Gulf, was
found, after being submerged only twenty months, to be covered with a
bed of coral two feet in thickness; he also mentions experiments made by
Mr. Allen on the coast of Madagascar, which tend to prove that in the
space of six months certain corals increased nearly three feet.

       *       *       *       *       *

We proceed to the theoretic explanation of these curious mineral
formations.

Naturalists and navigators have been much divided in opinion as to the
true origin of these madreporic islands. Most of them have admitted that
these enormous banks are composed of the mineral spoils and earthy
detritus of the madrepores and corals, which, developing themselves in
their midst, or upon the bed of the ocean, multiplying and superposing
themselves, age after age, and generation after generation, have finally
concluded by forming deposits of this immense extent. The growth of the
vast madreporic column would be finally arrested by the want of water
when its summit approached the level of the sea. It is thus that
Forster, Péron, Flinders, and Chamisso have explained the formation of
the _atolls_ and _madreporic_ reefs. This opinion has also found a
supporter, in our times, in the French admiral, Du Petit Thouars. But he
objects, with reason, that the corals cannot live at the prodigious
depth of sea at which the base of these islets lie. It has therefore
been found necessary to seek for another cause to satisfy the diverse
conditions of the phenomena, and explain, at the same time, the strange
circular arrangement of these islands, which is almost constant, and
which it is essential to keep in view.

Sir Charles Lyell was of opinion that the base of an atoll was always
the crater of an ancient submarine volcano, which, when crowned with
corals and madrepores, would naturally reproduce this circular wall
formed of heaped-up corals.

This theory supposes the existence of volcanic craters in the
neighbourhood of all the coral islands. It is quite certain that these
islands are often found not far from extinct volcanoes, and Sir Charles
Lyell has published a very curious map in connection with the subject;
nevertheless, the coincidence does not always exist. We have already
remarked on the theory by which Mr. Darwin seeks to explain the
complicated conditions of the phenomena. The explanation proposed
accounts for the known facts, as well as the present appearance of the
madreporic islands. The circular atolls and madreporic banks which are
disposed as a sort of girdle, are principally formed of _porites_,
_millepora_, and _astrea_, zoophytes which cannot exist at any great
depth in the ocean, but which swarm on the rocks at some few fathoms
only below the limits of the tide. These animals, by means of their
accumulated débris, soon form a sort of coating round the island, which
constitutes the littoral reefs: this marginal tongue or shoulder,
according to Mr. Darwin, is the first stage in the existence of a
madreporic island. At this point the author introduces a geological
cause, namely, a great subsiding movement of the soil, in which the
madreporic colony is sunk under the water. It is evident that after
submersion the zoophyte will only continue to develop itself on the
upper surface, and within the limits which its nature prescribes. The
madrepores exhibiting their greatest vitality at the points most exposed
to the fury of the waves, it will be near the outer edge of the reef
that the development will be most rapid. If the subsidence of the island
thus surrounded should still continue, as mountain after mountain and
island after island slowly sink beneath the water, fresh bases would be
successively afforded for the growth of the corals, and the outer edge
elevated by their continual labour, thus transforming the space into a
sort of circular lagune. The madreporic deposits would thus form an
isolated girdle, and the lagune, which occupies the centre, would become
deeper and deeper in proportion to the lowering of the soil. This is the
second stage of the madreporic isle.

The existence of the atolls are thus subordinated to two principal
conditions: the progressive subsidence of the shore washed by the sea,
and the existence of coral formed of stony cells, the growth and
multiplication of which are extremely rapid.

It follows from this that madreporic isles cannot exist in all seas;
that they only have their birth in the Torrid zone, or at least near the
Tropics, for it is only in these regions where the warmth exists, so
necessary to their development, that the madrepores show themselves in
greatest abundance.

The great field of madreporic formations, in short, is found in the warm
parts of the Pacific Ocean. It is from this point, as from a common
centre, round which are ranged the series of madreporic isles and
islets, that it will be useful, in concluding this chapter, to trace
their geographical distribution. We borrow the materials for this from
Milne Edwards's _tableaux_ of their distribution in the principal seas
of the world.

It is, as we have said, only in the warm parts of the Pacific Ocean that
the great mass of these islands are found. They give birth towards the
south to the group of atolls known as the archipelago of the Bashee
Islands, the extreme limit of the region being the Isle of Ducie. A
multitude of other islands of the same nature are sparsely scattered
over the sea, up to the east coast of Australia. There are enormous
areas here, in which every single island is of coral formation, and is
raised to the height at which the waves can throw up fragments. The
Radack group is an angular square, four hundred miles long by two
hundred and forty broad. Between this group and the Low Archipelago
itself, eight hundred and forty miles by four hundred and twenty, there
are groups and single islands covering a linear space of more than four
thousand miles. To the north of the Equator, the archipelago of the
Caroline Islands constitutes a very considerable group of madreporic
formation, comprehending upwards of a thousand, extending in a broad
belt over nearly forty degrees of longitude. On the other hand, all
along the coast of the American continent, round the Galapagos and the
Isle of Paques, we find no trace of them. The reason assigned is, that
in these regions a great current of cold water, flowing from the
Antarctic Pole, so much lowers the temperature of the sea, that the
zoophytes no longer possess the requisite vigour.

We still meet with atolls in the Chinese Seas, and madreporic barrier
reefs are abundant round the Marianne and Philippine Islands. These
marginal reefs form also an immense tract, from the Isle of Timor, along
the south coast of Sumatra, up to the island of Nicobar, in the Bay of
Bengal.

To the west of the Indian Peninsula, the Maldive and Laccadive Islands
form the extremity of another group of atolls, and important madreporic
reefs, which extend towards the south, by the Maldives and the Chagos
Islands; they consist of low coral formations, densely clothed with
cocoa-nut trees. The Maldives, the most southerly cluster, include
upwards of a thousand islands and reefs; the Laccadives, seventeen in
number, are of similar origin. The Saya de Malha bank, towards the
south-east, constitutes a further group of madreporic islets. Finally,
the coast of the Mauritius, of Madagascar, of the Seychelles, and even
the African continent, from the northern extremity of the Mozambique
Channel to the bottom of the Red Sea, are studded with numerous reefs of
the same nature. They fail, however, almost completely, along the coast
of the Asiatic continent, where, among others, the waters of the
Euphrates, the Indus, and the Ganges, enter the sea, and diversify its
inhabitants. The western coast of Africa, and the east coast of the
American continent, are almost entirely destitute of great madreporic
reefs, but they abound in the Caribbean Seas. In the Gulf of Mexico,
where the vast fresh-water current of the Mississippi debouches into the
sea, they are unknown. It is principally on the north coast and upon the
eastern flanks of the chain of West Indian Islands that the madreporic
reefs show themselves in these regions.

       *       *       *       *       *

The polyps which have produced these vast ranges of islands would be set
down, at first sight, as the most incapable objects in creation for
accomplishing it. In the case of the _Pennatulidæ_, the case is
coriaceous, strengthened with calcareous particles; the interior is a
fibrous network containing a transparent jelly in the squares, and
permeated by a certain number of longitudinal cartilaginous tubes; the
soft part is uniformly gelatinous, but the skin is also coriaceous, with
a great number of calcareous spicula placed parallel to one another,
adding greatly to its strength and consistency.

The polyps are placed in this external fleshy crust; their position
being marked by an orifice on the surface, distinguished by eight
star-like rays, which open when the upper portion of the body is forced
outwards, in which state it resembles a cylindrical bladder or nipple
crowned with a fringe of tentacula, which surround the mouth. Under this
orifice is the stomach, occupying the centre of the cylinder. The space
between this stomach and the outer envelope is divided into eight equal
compartments or cells by as many thin septa, originating in a labial rim
or lip between the basis of the tentacula, which descend through the
cylinder attached on the one side to the inner tunic of the body, and on
the other to the stomach, which is thus retained in its position.

The protruding portion of the polyp is very delicate, the internal
viscera being, as it were, enclosed in a bladder formed of two very thin
membranes in intimate union, so transparent as to permit a view of their
arrangement. At the base of the body, where thickest, it coalesces with
the base of the adjacent polyp; thus constituting the common cortical
portion into which each animal retreats at will, by a process in many
respects resembling that by which a snail draws in its horns. In the
greater number of _Asteroidæ_ this common portion secretes carbonate of
lime, which is deposited in the meshes of its tissues either in granules
or in crystalline spiculæ, which imparts a solid consistency to the
whole. The inner tissue meanwhile continues unaltered, being prolonged
throughout the polypiferous lining of the cell, the abdominal cavity,
and the longitudinal canals which permeate the whole polyp, as well as
the tubular network with which the space between the canals is occupied.
It is among these inner tissues that the buds or gemmæ are generated, by
whose increase and evolution the polyp mass is enlarged, the shape and
size depending on the manner in which the buds are evolved; for in some,
as in the _Pennatulidæ_, determinate spots only have the appropriated
organization, while in others, as in _Alcyonium_, the generative faculty
appears to be undefined and more diffused.


THE ACTINIARIA.

Here we leave the group of polyps which form united families. The Sea
Anemones, of which the _Actinia_ are the type, consist of _Zoanthaires_,
which produce no corals, that is to say, of polyps whose covering
remains always soft, and in whose interior nothing solid is produced.
This order is usually divided into two families--the _Actiniadæ_, having
the tentacles in uninterrupted circles, with no corallum, and the
_Minyadinæ_, having globose bodies, and very short tentacula.

The modern aquarium exposes the spectator to many wonderful surprises.
Coiled up against the transparent crystal walls of the basin, he
observes living creatures of the most brilliant shades of colour, and
more resembling flowers than animals. Supported by a solid base and
cylindrical stem, he sees them terminate like the corolla of a flower,
as in the petals of the anemone: these are the animals we call _Sea
Anemones_--curious zoophytes, which, as all persons familiar with the
sea shore may have observed, are now seen suspended from the rocks, and
presently buried at the bottom of the sea, or floating on its surface.
These charming and timid creatures are also called _Actinia_, as
indicating their disposition to form rays or stars, from the Greek
ἀκτὶν, a ray.

The body of these animals is cylindrical in form, terminating beneath in
a muscular disk, which is generally large and distinct, enabling them to
cling vigorously to foreign bodies. It terminates above in an upper
disk, bearing many rows of tentacles, which differ from each other only
in their size. These tentacles are sometimes decorated with brilliant
colours, forming a species of collarette, consisting of contractile and
often retractile tubes, pierced at their points with an orifice, whence
issue jets of water, which is ejected at the will of the animal.
Arranged in multiples of circles, they distribute themselves with
perfect regularity round the mouth. These are the arms of this species
of zoophyte.

The mouth of the Actinia opens among the tentacles. Oval in form, it
communicates by means of a tube with a stomach, broad and short, which
descends vertically, and abuts by a large opening on the visceral
cavity, the interior of which is divided into little cells or chambers.
These cells and chambers are not all of the same dimensions; in parting
from the cylindrical walls of the body, they advance, the one
increasing, the others getting smaller, in the direction of the centre.
Moreover, they have many kinds of cells, which dispose themselves in
their different relations with great regularity--their tentacula, which
correspond with them, being arranged in circles radiating more or less
from the centre.

The stomach of the sea anemones fulfils a multitude of functions. At
first, it is the digestive organ; it is also the seat of respiration;
and is unceasingly moistened by the water, which it passes through,
imbibes, and ejects. The visceral cavity absorbs the atmospheric air
contained in the water; for the stomach is also a lung, and through the
same organ it ejects its young! In short, the reproductive organs, the
eggs, and the larvæ, are all connected with the tentacles or arms. In
the month of September the eggs are fecundated, and the larvæ or embryos
developed. As Frédol says in "La Monde de la Mer," "These animals bear
their young, not upon their arms, but in their arms. The larvæ generally
pass from the tentacula into the stomach, and are afterwards ejected
from the mouth along with the rejecta of their food--a most singular
formation, in which the stomach breathes, and the mouth serves the
purposes of accouchement--facts which it would be difficult to believe
on other than the most positive evidence."

"The Daisy-like Anemones (_Sagartia bellis_--Gosse), in the Zoological
Gardens of Paris," says Frédol, "frequently throw up little embryos,
which are dispersed, and attach themselves to various parts of the
aquarium, and finally become miniature anemones exactly like the parent.
An actinia which had taken a very copious repast ejected a portion of it
about twenty-four hours later, and in the middle of the ejected food
were found thirty-eight young individuals." According to Dalyell, an
accouchement is here a fit of indigestion.

The lower class of animals have, in fact, as the general basis of their
organization, a sac with a single opening, which is applied, as we have
seen, to a great variety of uses. It receives and rejects; it swallows
and it vomits. The vomiting becomes necessary and habitual--the normal
condition, in short, of the animal--and is perhaps a source of pleasure
to it, for it is not a malady, but a function, and even a function
multiplied. In the sea anemone it expels the excrement, and lays its
eggs; in others, as we have seen, it even serves the purposes of
respiration; so that the animal flowers may probably be said to enjoy
their regular and periodical vomit.

The sea anemones multiply their species in another manner. On the edge
of their base certain bud-like excrescences may often be observed. These
buds are by-and-by transformed into embryos, which detach themselves
from the mother, and soon become individuals in all respects resembling
her. This mode of reproduction greatly resembles some of the vegetative
processes. Another and very singular mode of reproduction has been noted
by Mr. Hogg in the case of _Actinia oeillet_. Wishing to detach this
anemone from the aquarium, this gentleman used every effort to effect
his purpose; but only succeeded, after violent exertions, in tearing
the lower part of the animal. Six portions remained attached to the
glass walls of the aquarium. At the end of eight days, attempts were
again made to detach these fragments; but it was observed, with much
surprise, that they shrank from the touch and contracted themselves.
Each of them soon became crowned with a little row of tentacula, and
finally each fragment became a new anemone. Every part of these strange
creatures thus becomes a separate being when detached, while the
mutilated mother continues to live as if nothing had happened. In short,
it has long been known that the sea anemones may be cut limb from limb,
mutilated, divided, and subdivided. One part of the body cut off is
quickly replaced. Cut off the tentacles of an actinia, and they are
replaced in a short time, and the experiment may be repeated
indefinitely. The experiments made by M. Trembley of Geneva upon the
fresh-water polypi were repeated by the Abbé Dicquemare on the sea
anemones. He mutilated and tormented them in a hundred ways. The parts
cut off continued to live, and the mutilated creature had the power of
reproducing the parts of which it had been deprived. To those who
accused the Abbé of cruelty in thus torturing the poor creatures, he
replied that, so far from being a cause of suffering to them, "he had
increased their term of life, and renewed their youth."

The _Actiniadæ_ vary in their habitat from pools near low-water mark to
eighteen or twenty fathoms water, whence they have been dredged up.
"They adhere," says Dr. Johnston, "to rocks, shells, and other
extraneous bodies by means of a glutinous secretion from their enlarged
base, but they can leave their hold and remove to another station
whensoever it pleases them, either by gliding along with a slow and
almost imperceptible movement (half an inch in five minutes), as is
their usual method, or by reversing the body and using the tentacula for
the purpose of feet, as Réaumur asserts, and as I have once witnessed;
or, lastly, inflating the body with water, so as to render it more
buoyant, they detach themselves, and are driven to a distance by the
random motion of the waves. They feed on shrimps, small crabs, whelks,
and similar shelled mollusca, and probably on all animals brought within
their reach whose strength or agility is insufficient to extricate them
from the grasp of their numerous tentacula; for as these organs can be
inflected in any direction, and greatly lengthened, they are capable of
being applied to every point, and adhere by suction with considerable
tenacity, throwing out, according to Gaertner, of their whole surface a
number of extremely minute suckers, which, sticking fast to the small
protuberances of the skin, produce the sensation of roughness, which is
so far from being painful that it even cannot be called disagreeable.

"The size of the prey is frequently in unseemly disproportion to the
preyer, being often equal in bulk to itself. I had once brought me a
specimen of _A. crassicornis_, that might have been originally two
inches in diameter, which had somehow contrived to swallow a valve of
_Pecten maximus_ of the size of an ordinary saucer. The shell, fixed
within the stomach, was so placed as to divide it completely into two
halves, so that the body, stretched tensely over, had become thin and
flattened like a pancake. All communication between the inferior portion
of the stomach and the mouth was of course prevented; yet, instead of
emaciating and dying of atrophy, the animal had availed itself of what
undoubtedly had been a very untoward accident to increase its enjoyment
and its chance of double fare. A new mouth, furnished with two rows of
numerous tentacula, was opened up on what had been the base, and led to
the under stomach; the individual had indeed become a sort of Siamese
Twin, but with greater intimacy and extent in its unions!"

The sea anemones pass nearly all their life fixed to some rock, to which
they seem to have taken root. There they live a sort of unconscious and
obtuse existence, gifted with an instinct so obscure that they are not
even conscious of the prey in their vicinity until it is actually in
contact, when it seizes it in its mouth and swallows it. Nevertheless,
though habitually adherent, they can move, gliding and creeping slowly
by successive contractile and relaxing movements of the body, extending
one edge of their base and relaxing the opposite one.

At the approach of cold weather the _Actiniadæ_ descend into the deepest
water, where they find a more agreeable temperature.

We have said that the sea anemones are scarcely possessed of vital
instinct; but they are capable of certain voluntary movements. Under the
influence of light, they expand their tentacles as the daisy displays
its florets. If the animal is touched, or the water is agitated in its
neighbourhood, the tentacles close immediately. These tentacles appear
occasionally to serve the purpose of offensive arms. The hand of the
man who has touched them becomes red and inflamed. M. Hollard has seen
small mackerel, two to three inches long, perish when touched by the
tentacles of the Green Actinia (_Comactis viridis_--Allman). This is a
charming little animal. "The brilliancy of its colours and the great
elegance of its tentacular crown when fully expanded," says Professor
Allman, "render it eminently attractive; hundreds may often be seen in a
single pool, and few sights will be retained with greater pleasure by
the naturalist than that presented by these little zoophytes, as they
expand their green and rosy crowns amid the algæ, millepores, and plumy
corals, co-tenants of their rock-covered vase."

The toxological properties of the Actinia have been attributed to
certain special cells full of liquid; but M. Hollard believes that these
effects are neither constant enough nor sufficiently general to
constitute the chief function of these organs, which are found in all
the species and over their whole surface, external and internal. Though
quite incapable of discerning their prey at a distance, the sea anemone
seizes it with avidity when it comes to offer itself up a victim. If
some adventurous little worm, or some young and sluggish crustacean,
happens to ruffle the expanded involucrum of an actinia in its lazy
progress through the water, the animal strikes it at once with its
tentacles, and instinctively sweeps it into its open mouth. This habit
may be observed in any aquarium, and is a favourite spectacle at the
"Jardin d'Acclimatation" of Paris, at noon on Sunday and Wednesday, when
the aquatic animals are fed. Small morsels of food are thrown into the
water. Prawns, shrimps, and other crustaceans and zoophytes inhabiting
this medium, chase the morsels as they sink to the bottom of the basin;
but it is otherwise with the Actinia; the morsels glide downwards within
the twentieth part of an inch of their crown without its presence being
suspected. It requires the aid of a propitious wand, directed by the
hand of the keeper, to guide the food right down on the animal. Then its
arms or tentacles seize upon the prey, and its repast commences
forthwith.

The Actinia are at once gluttonous and voracious. They seize their food
with the help of the tentacula, and engulf in their stomach, as we have
seen, substances of a volume and consistence which contrast strangely
with their dimensions and softness. In less than an hour, M. Hollard
observed that one of these creatures voided the shell of a mussel,
and disposed of a crab all to its hardest parts; nor was it slow to
reject these hard parts, by turning its stomach inside out, as one might
turn out one's pocket, in order to empty it of its contents. We have
seen in Dr. Johnston's account of _A. crassicornis_ that when threatened
with death by hunger, from having swallowed a shell which separated it
into two halves, at the end of eleven days it had opened a new mouth,
provided with separate rows of tentacula. The accident which, in
ordinary animals, would have left it to perish of hunger, became, in the
sea anemone, the source of redoubled gastronomical enjoyment.

[Illustration: Plate V.--Sea Anemones.

    1, 2, 3. A. sulcata.
    4. Phymactis sanctæ Helenæ.
    5. Actinia capensis.
    6. A. Peruviana.
    7. A. sanctæ Catherinæ.
    8. A. amethystina.
    9. Comactis viridis.
]

"The anemones," Frédol tells us, "are voracious, and full of energy;
nothing escapes their gluttony; every creature which approaches them is
seized, engulfed, and devoured. Nevertheless, with all the power of
their mouth, their insatiable stomachs cannot retain the prey they have
swallowed. In certain circumstances it contrives to escape, in others it
is adroitly snatched away by some neighbouring marauder more cunning and
more active than the anemone."

In PL. IV. are represented the principal species of Anemone usually
observed in the aquarium. Figs. 1, 2, and 3, _A. sulcata_, is surmised
by Johnson to be the young of _A. effoeta_ (Linn.). It is also quoted as
a synonyme of _Anthea cereus_, from Drayton's stanza:

    "Anthea of the flowers, that hath a general charge,
    And Syrinx of the weeds, that grow upon the marge."

Fig. 4, _Phymactis Sanctæ Helenæ_ (Edw.); Fig. 5, _A. Capensis_
(Lesson); Fig. 6, _A. Peruviana_ (Lesson); Fig. 7, _A. Sanctæ
Catherinæ_; Fig. 8, _A. amethystina_ (Quoy); Fig. 9, _Comactis viridis_
(Milne Edwards).

"It is sometimes observed in aquariums that a shrimp, which has seen the
prey devoured from a distance, will throw itself upon the ravisher, and
audaciously wrest the prey from him and devour it before his eyes, to
his great disappointment. Even when the savoury morsel has been
swallowed, the shrimp, by great exertions, succeeds in extracting it
from the stomach. Seating itself upon the extended disk of the anemone,
with its small feet it prevents the approach of the tentacles, at the
same time that it inserts its claws into the digestive cavity and seizes
the food. In vain the anemone tries to contract its gills and close its
mouth. Sometimes the conflict between the sedentary zoophyte and the
vagrant crustacean becomes serious. When the former is strong and
robust, the aggression is repelled, and the shrimp runs the risk of
supplementing the repast of the anemone."

If the actinias are voracious, they can also support a prolonged period
of fasting. They have been known to live two and even three years
without having received any "nourishment."[7]

Although the sea anemone is said to be delicate eating, man derives very
little benefit from them in that respect. In Provence, Italy, and
Greece, the Green Actinia is in great repute, and Dicquemare speaks of
_A. crassicornis_ as delicate food. "Of all the kinds of sea anemones, I
would prefer this for the table; being boiled some time in sea water,
they acquire a firm and palatable consistence, and may then be eaten
with any kind of sauce. They are of an inviting appearance, of a light
shivering texture, and of a soft white and reddish hue. Their smell is
not unlike that of a warm crab or lobster." Dr. Johnston admits the
tempting description, and does not doubt their being not less a luxury
than the sea urchins of the Greeks, or the snails of the Roman epicures,
but he was not induced to test its truth. Rondeletius tells us, having,
as Dr. Johnston thinks, _A. crassicornis_ in view, that it brings a good
price at Bordeaux. _Actinia dianthus_ also is good to eat, quoth
Dicquemare, and Plaucus directs the cook to dress it after the manner of
dressing oysters, with which it is frequently eaten. _Actinia coriacea_
is found in the market at Rochefort during the months of January,
February, and March. Its flesh is said to be both delicate and savoury.

With these general considerations, we proceed to note some of the more
remarkable genera and species of these interesting creatures. Among
these, the species represented in PL. IV. are those usually seen
collected in such aquariums as those of the Zoological Gardens of London
and the Gardens of Acclimatization of Paris.

The first section of the _Actiniadæ_, according to Milne Edwards,
includes the Common Actinia, the feet of which are broad and adherent,
the lateral walls soft and imperforate. To this section belongs, among
others, the genera _Anemonia_, _Actinia_, and _Metridium_.

[Illustration: Plate VI.--Sea Anemones.

    1. Actinia dianthus.
    2. Cereus gemmaceus.
    3. Actinia bicolor.
    4. Sagartia viduata.
    5. Cereus papillossus.
    6. Actinia picta.
    7. Actinia equina.
    8. Sagartia rosea.
    9. Sagartia coccinea.
]

The Green Actinia (_A. viridis_) has very numerous tentacula, sometimes
as many as two hundred, exceeding in length the breadth of the body, of
a fine brownish or olive green, and rose-coloured at the extremity. The
trunk is of a greyish green or brown; the disk is brown with greenish
rays. This species is plentiful in the Mediterranean and in the Channel.
When attached to the vertical sides of a rock, a little below the
surface of the water, in which position it is often seen on the shores
of the Mediterranean, the tentacles hang suspended as if the animal had
no power to display them in their radiate form; but when fixed
horizontally in a calm sea, they are spread out in all directions, and
are kept in a state of continual agitation; its long, mane-like
tentacula, fully expanded, float and balance themselves in the water in
spite of the action of the waves, presenting a most interesting
spectacle as it displays its beauties a few feet below the passing boat.

_A. dianthus_ (Ellis), having a number of synonymes, is represented in
PL. V. Fig. 1; its body is smooth and cylindrical; the disk marked in
the centre with clavate radiating bands; tentacula numerous, irregular,
the outer small, and forming round the margin a thick filamentous
fringe. This species attaches itself to rocks and shells in deep water,
or within low-water mark, to which it permanently attaches itself, and
cannot be removed without organic injury to the base. When contracted,
the body presents a thick, short, sub-cylindrical form, about three
inches long, and one and a half in diameter, and about five inches when
fully expanded; the skin is smooth, of an uniform olive, whitish, cream,
or flesh colour. The centre of the disk is ornamented with a circle of
white bands, radiating from the mouth, the lamellæ running across, the
circumference being perceptible through the transparent skin. From the
narrow, colourless interspaces between the lamellæ the tentacula
originate. "They are placed," says Dr. Johnston, "between the mouth and
the margin, which is encircled by a dense fringe of incontestable
beauty, composed of innumerable short tentacula or filaments, forming a
thick, furry border." In PL. V. Fig. 2, we have probably Gaertner's
_Anthea cereus_, the body of which is a light chestnut colour, smooth,
sulcated lengthwise, with tentacula rising from the disk to the number,
in aged animals, of two hundred. _Sagartia viduata_--Gosse (Fig. 4) has
the body adherent, cylindrical, without a skin, destitute of warts,
emitting capsuliferous filaments from pores; nettling-threads short,
densely armed with a brush of hairs; tentacles conical. _A. picta_ (PL.
IV. Fig. 6), which Professor Edward Forbes changes to _Adamsia
palliata_, is described by Mr. Adams, who first discovered it, "as
longitudinally sulcated, having the edges of the base crenated; the
lower part an obscure red, and the upper part transparent white, marked
with fine purple spots; the outer circumference of the aperture has a
narrow stripe of pink. When expanded, the superior division of the body
seems formed of membrane. From perforated warts placed without order on
the outer coat, issued white filamentous substances variously twisted
together. I have observed," he adds, "similar bodies ejected from the
mouths of all the species of this genus which have fallen within my
notice."

_A. mesembryanthemum_ (Johnston).--The _A. equina_ of Lesson (PL. IV.
Fig. 6), known in France as the _Cul d'ane_, is extremely common in the
Channel on rocks between the tide marks. It attaches itself chiefly to
rocks beaten by the waves and exposed to view at the moment of reflux.
The body is from two to three inches in height, and from an inch to an
inch and a half in diameter; hemispherical when contracted, it resembles
a bell perforated at the summit, dilated into a cylinder. When fully
extended the tentacula are nearly equal to the height of the body, of a
uniform liver colour, or olive green, and sometimes streaked with blue,
having a greenish line either continuous or in spots, the base generally
of a greenish colour encircled with an azure blue line, often streaked
with red. The tentacula are terminated by a small pore. Its colour is
variable, but generally it is of a violet-red. Sometimes it presents
round spots of a fine green; at other times it is only of a greenish
hue; the edge of the feet have a narrow border of red, with green and
blue beneath.

_Metridium dianthus_ has a thick body with russet grey skin, the disk
strongly lobed, thin and transparent round the mouth; the tentacula very
numerous, very short, and occupying a broad, strong zone upon the disk.
The mesial lines are whitish and wide apart; externally they are closer,
papiliform, and brown. This species is found on stones and shells in the
North Sea and in the Channel.

       *       *       *       *       *

The verrucous, or warty section of the _Actiniadæ_, have the lateral
walls of the body covered with agglutinated tubercles, and
well-developed feet. To this section belong the Coriaceous Cereus,
_Actinia crassicornis_ (Johnston), and _A. senilis_ (Hollard and
Dicquemare), which seem to vary in habit. Hollard describes them as
frequently buried in the sands on the shore, while Cocks describes them
"as attaching themselves to shells and stones in deep water, or attached
on the littoral to the sides of rocks, in crevices, or on the face of
clean stones in sheltered places." The body is variegated, green, and
red; the tentacles thick, short, and greyish, with broad roseate bands.

[Illustration: Fig. 80. Edwardsia Calimorpha (Gosse).]

The Anemones belonging to the fourth section, or tap-rooted actinia,
have the base small, and terminating in a rounded point, and the body
much elongated, as in _Edwardsia Calimorpha_ (Fig. 80), in which the
body is non-adherent, somewhat worm-like, having the mouth and tentacula
seated on a retractile column, the lower extremity inflated, membranous,
and retractile.

In the great family of the Actiniarians, Milne Edwards forms a special
group of the Phyllactinæ. In this group the polyps are simple, fleshy,
and present at once simple and composite tentacula. Such is _Phyllactis
prætexta_ (Fig. 81), which is found in the neighbourhood of Rio Janeiro.
The zoophyte fixes itself upon the rocks on the sea shore, and covers
itself with sand. Its trunk, of cylindrical form, is of a flesh-colour,
with vertical lines, having red points. The interior tentacles form two
simple elongated rows; the exterior tentacles are spatulate and lobed,
not very unlike the leaves of the oak.

Another group, that of the Thalassianthidæ, is distinguished from the
preceding by having all its tentacula short, pinnate, and branching, or
papilliferous. One species only is known, _T. aster_, of a slate colour,
which inhabits the Red Sea.

[Illustration: Fig. 81. Phyllactus prætexta (Dana), natural size.]

In the last group of Actiniadæ, as arranged by Milne Edwards, the
polypes occur in clusters, and are multiplied by buds, rising from a
common creeping, root-like, fleshy base; they thus present a sort of
coriaceous polypier, as in _Zoanthus socialis_ (Fig. 82). In the British
Channel this species, which Dr. Johnston has named _Z. Couchii_, after
Mr. Couch, jun., is found along the Cornish coast, on flat slates and
rocks, in deep water, and from one to ten leagues from the shore. It is
very small, resembling, both in shape and size, a split pea. When
living, its surface is plain but glandular, becoming corrugated when
preserved. When semi-expanded, which is its favourite state, it elevates
itself to twice its ordinary height, becoming contracted about the
middle, like an hour-glass. When the creature is fully expanded, the
tentacula become distended and elongated to about the length of the
transverse diameter of the body; and they are generally darker at their
extremities than towards the base. Like all the Actiniadæ, the present
species possess a power of considerably altering their shape; sometimes
the mouth is depressed, and at others it is elevated into an obtuse
cone. "This is one of the most inactive of its order," says Mr. A.
Couch; "for, whether in a state of contraction or expansion, it will
remain so for many days without apparent change. In its expanded state a
touch will make it contract, and it will commonly remain so for many
days." The trailing connecting-band is flat, thin, narrow, glandular,
and of the same texture as the polyp, sometimes enlarging into small
papillary eminences, which, as they become enlarged, become developed
into polyps.

[Illustration: Fig. 82. Zoanthus socialis (Cuvier), natural size.]


MINYADINIANS.

[Illustration: Fig. 83. Blue Minyade. Minyas coeulea (Cuvier), natural
size.]

The Minyadinians seem to represent among the Zoanthairia the form
peculiar to the Pennatula among the Alcyonians. In the case of these
animals, the base of the body, in place of extending itself in a
disk-like form, in order to grapple with the rock and other projections
at the bottom of the sea, turns itself inwards, forming a sort of purse,
which seems to imprison the air. From this results a sort of hydrostatic
apparatus, aided by which the animals can float in the water and
transport themselves from one place to another. The Blue Minyade
(_Minyas cyanea_--Fig. 83) will serve as a type of this family; its
globose, melon-like form is of azure blue, studded with white wart-like
excrescences; it is flattened at its two extremities in its state of
contraction, and it has three rows of tentacula, which are short,
cylindrical, and white. The internal organs are of a delicate rose
colour. Cuvier places this species among the Echinodermata, but the
observations of Lesueur and Quoy, who were acquainted with the living
animal, place it among the Actiniadæ. Many of the species, which are
usually fixed, are still capable of swimming and of inflating their
suctorial disks; therefore it is by no means certain that the free habit
of _Minyas cyanea_ is constant.


FOOTNOTES:

[Footnote 6: "Cours de Paleontologie Stratigraphique."]

[Footnote 7: "On en a vu vivre deux et même trois ans, sans recevoir de
nourriture."--_Vie des Animaux_, p. 117.]



CHAPTER VIII.

ACALEPHÆ, OR SEA NETTLES.

"In nova fert animus mutatis dicere formas corpora."--OVID, MET.


The class Acalephæ, from ἀκαλήφη, a nettle, so called from the
stinging properties which many of them possess, include a great number
of radiate animals of which the Medusæ are the type. They form the third
class of Cuvier's zoophytes. The Acalephæ, forming the first order, are
characterised as floating and swimming in the sea by means of the
contraction and dilation of their bodies, their substance being
gelatinous, without apparent fibres.

The great genus Medusa is characterised by having a disk, more or less
convex above, resembling a mushroom or expanded umbrella--the edges of
the umbrella, as well as the mouth and suckers, being more or less
prolonged into pedicles, which take their place in the middle of the
lower surface; they are furnished with tentacula, varying in form and
size, which have given rise to many subdivisions, with which we need not
concern ourselves.

The substance of the disk presents an uniform cellular appearance
internally, but the cellular substance being very soft, no trace of
fibre is observable. Taken from the sea and laid upon a stone, a Medusa
weighing fifty ounces will rapidly diminish to five or six grains,
sinking into a sort of deliquescence, from which Spalanzani concluded
that the sea-water penetrated the organic texture of its substance, and
constituted the principal volume of the animal. Those which have cilia
round their margins have also cellular bands running along their bases,
and most of the projectile and extensile tentacula and filaments have
sacs and canals containing fluids at their roots. Suckers are also found
at the extremities, and along the sides of these tentacles in several
genera are suckers, by which they are able more securely to catch their
floating prey, or to anchor themselves when at rest. The indications of
nerves or nervous system are too slight to be received as evidence,
although Dr. Grant observed some structure which he thought could only
belong to a nervous system, and Ehrenberg thought he observed eyes in
_Medusa aurita_, as well as a nervous circle formed of four
ganglion-like masses disposed round the mouth. But most naturalists seem
to be of opinion that touch is the only sense of which any conclusive
proof can be advanced.

Here we behold a class of bell-shaped semi-transparent organisms, which
float gracefully in the sea--a great family of soft, wandering animals,
constituted in a most extraordinary manner. They look like floating
umbrellas, breeches, or, better still, floating mushrooms, the footstalk
replaced by an equally central body, but divided into divergent lobes at
once sinuous, twisted, and fringed, so that one is at first tempted to
take them for a species of root. The edges of the umbrella or mushroom
are entire or dentate, sometimes elegantly figured, often ciliate, or
provided with long filiform appendages which float vertically in the
water.

Sometimes the animal is uncoloured, and limpid as crystal; sometimes it
presents a slightly opaline appearance, now of a tender blue, or of a
delicate rose colour; at other times it reflects the most brilliant and
vivid tints.

In certain species the central parts only are coloured, showing
brilliant reds and yellows, blues or violets, the rest being colourless.
In others the central mass seems clothed in a thin iridescent or
diaphanous veil, like the light evanescent soap-bubble, or the
transparent glass shade which covers a group of artificial flowers.

The Acalephæ are animals without consistence, imbued with much water, so
that we can scarcely comprehend how they resist the agitation of the
waves and the force of the currents; the waves, however, float without
hurting them, the tempest scatters without killing them. When the sea
retires, or they are withdrawn from their native waters, their substance
dissolves, the animal is decomposed, they are reduced to nothing; if the
sun is ardent, this disorganisation occurs in the twinkling of an eye,
so to speak.

When the Medusæ travel, their convex part is always kept in advance, and
slightly oblique. If they are touched while swimming, even lightly, they
contract their tentacula, fold up their umbrella, and sink into the sea.
Like Ehrenberg, M. Kölliker thought he discovered visual and auditory
organs in an _Oceania_, and Gegenbauer thought he detected them in other
genera, such as _Rhizostoma_ and _Pelagia_. The eyes are said to consist
of certain small, hemispherical, cellulose, coloured masses, in which
are sunk small crystalline globules, the free parts of which are
perfectly naked. The supposed auditory apparatus is seated close to
these organs; they are small vesicles filled with liquid; the eyes
having neither pupil nor cornea, and the ears without opening or arch.

But it is in their reproduction that these evanescent beings present the
most marvellous phenomena. At one period of the year the Medusæ are
charged with numbers of very minute eggs, of the most lively colours,
which are suspended in large festoons from their floating bodies. In
some cases these eggs develop themselves grafted to their bodies, and
are only detached at maturity. In other cases the larvæ produced bear no
resemblance to the mother; they are elongated and vermiform, broad at
their extremity; we speak of the microscopic _leeches_, which have
vibrating cilia, scarcely perceptible, by which they execute the most
lively motions. At the end of a certain time they are transformed into
polyps, and furnished with eight tentacula. This preparatory sort of
animal seems to possess the faculty of reproduction by means of certain
buds or tubercles which develop themselves on the surface of the body,
and also by filaments which start up here and there, so that a single
individual originates a numerous colony. This polyp is subjected to a
transformation still more remarkable; its structure becomes complex, its
body articulate, and it seems to be composed of a dozen disks piled one
upon the other, like the jars of a voltaic pile; the upper disk is
convex, and is separated from the colony after a convulsive effort; it
becomes free, and an excessively small, star-like Medusa is the result;
every disk, that is, every individual, is isolated one after the other
in the same manner.

Thus of the sexual zoophytes which propagate their kind according to the
usual laws; but others engender young which have no resemblance to the
parent zoophyte at all: in this respect they are neuter, that is,
non-sexual, or _agamous_. These are produced by budding, or fissiparity,
from individuals like themselves. They can also give sexual
distinctions; but before this change takes place the creature, which was
simple, is transformed into a composite animal, and it is from its
disaggregation that individuals having sexual organs are produced, the
process being that which has been called _alternate_ generation. It goes
on in a perfectly regular manner, although it is a fact that the young
never resemble their mothers, but their grandmothers.

This great family of Zoophytes Gosse divides into--

_Discophora_, having the body in the form of a circular disk, more or
less convex and umbrella-shaped, moving by alternate contractions and
expansions of the disk.

[Illustration: Fig. 84. Æquerea violacea, natural size (Milne Edwards).]

_Ctenophora_, body cylindrical, moving by means of many parallel rims of
cilia set in longitudinal lines on the surface.

_Sophonophora_, body irregular, without central digestive cavity like
the others, having sucking organs, and moving by means of a contractile
cavity, or by air-vessels.

[Illustration: Fig. 85. Aurelia aurita (Lamarck). Cyanea aurita
(Cuvier). One-third natural size.]

The Discophora are again subdivided into _Gymnophthalmata_, having the
eye-specks uncovered or wanting, a great central digestive cavity,
circulating vessels proceeding to the margin quite simple or branched;
and _Steganophthalmata_ having the eye-specks protected by membranous
hoods, or lobed coverings, circulating vessels much ramified, and united
with a network. Of the Gymnophthalmata we have an example in _Æquerea
violacea_ (Fig. 84), in which the disk is slightly convex, glass-like in
appearance, and furnished all round with very short, slender,
thread-like, violet-coloured tentacula; with circulating vessels, eight
in number, quite simple, and ovaries placed on them; peduncle wide,
expanding into many broad and long fringed lobes. The Steganophthalmata
include the _Medusadæ_ proper, in which the umbel is hemispherical, with
numerous marginal tentacles, eight eyes covered by lobes, four ovaries,
four chambers, four fringed arms, with a central and four lateral
openings. _Aurelia aurita_ (Fig. 85) is here represented as a type of
the group; it is plentiful in the Baltic, and has been carefully studied
by the Swedish naturalists. Rosenthal has made its anatomy his special
study. Sars has also made it the subject of observations. In the same
group we find the _Pelagia cyanella_ of Péron, whose body is globose,
scolloped with eight marginal tentacles, peduncles ending in four
leaf-like, furbelowed arms, united at the base, having four ovaries, and
appendages to the stomach, without orifices.

The _Pelagia_, as the name implies, belong to the deep sea. _P.
noctiluca_ has a transparent, glass-like disk, of a reddish-brown colour
and warty appearance. It is found in the Mediterranean, about the coast
near Nice, and is still more plentiful on the coast of Sicily, and on
the African coast. Another species, _P. panopyra_, is very common in the
Atlantic and Pacific, between the Tropics. The naturalist Lesson met
whole banks of them in the equatorial ocean, about the twenty-seventh
degree north latitude and the twenty-second degree west longitude.
During the night, this species emits a brilliant phosphoric light, and
living individuals, which Lesson succeeded in preserving, exhibited
great luminosity in the dark. This medusa is remarkable for its
semi-spherical disk, slightly depressed, umbilicate at the summit, a
little compressed at the edges, and densely bristling on the surface
with small elongated warts, but regularly festooned along the edges. In
colour it is a delicate rose.

       *       *       *       *       *

The animals which constitute this class of Zoophytes, and, in former
times, so curious and so imperfectly known, were designated
_Polypomedusæ_, in order to remind us that at one time they were called
Medusæ, and at others ranged among the Polyps. It has, however, been
recently discovered that, shortly after they issue from the egg, these
zoophytes show themselves in the form of polyps, and that, at a later
period, they assume the animal form, to which we give the name of
medusæ. These animals are, then, true proteans: hence the very
considerable difficulty of studying them--difficulties which have long
reduced naturalists to despair. Even now their history is too obscure
and too complicated to justify us in presenting it, except in its
general features. We shall, therefore, content ourselves here with a
description of the best known species of the class only--those, namely,
which have particularly attracted the attention of naturalists, and
which are, at the same time, of a nature to interest our readers.

The class of Discophoræ may be divided into four orders or families,
namely:--

     I. THE HYDRAIDÆ, having single, naked, gelatinous, sub-cylindrical,
     but very contractile stems, mutable in form, mouth encircled with
     a single series of granulous filiform tentacula.

     II. SERTULARIADÆ, plant-like and horny, rooted and variously
     branched, filled with semi-fluid organic pulp, the polyps contained
     within sessile cells disposed along the sides of the main stem or
     branchlets, but never terminal.

     III. MEDUSADÆ. Umbel hemispherical, with marginal tentacula; having
     eight eyes covered by lobes, four ovaries, four cells, four fringed
     arms, a central opening, and four lateral openings.

     IV. SIPHONOPHORA, having the animals double, and bell-shaped, one
     fitting into the cavity of the other; in _Dyphyes_ the animal has a
     large air-vessel with numerous tentacula; in _Physalia_, the animal
     stretches over a cartilaginous plane.

     The true form of the Medusa does not appear in the two first
     orders.


HYDRAIDÆ.

The Hydraidæ are, according to modern naturalists, Discophoræ arrested
in their development. They comprehend the single genus Hydra, of which
many species are known, whose habits and metamorphoses it will be our
object to particularise.

_Hydra vulgaris_ inhabits stagnant ponds and slowly-running waters. It
is of an orange-brown or red colour, the intensity of the colour
depending on the nature of its food, becoming almost blood-red when fed
on the small crimson worms and larvæ to be found in such places. M.
Laurent even succeeded in colouring them blue, red, and white, by means
of indigo, carmine, and chalk, without any real penetration of the
tissue, the buds from them acquiring the same colour as the mother,
while the colour of the ova retains its natural tint, even when the
Hydra mother has been fed with coloured substances during the progress
of this mode of reproduction. The tentacula, usually seven or eight in
number, never exceed the length of the body, tapering insensibly to a
point.

_Hydra viridis_, the fresh-water polyp, being more immediately within
the sphere of our observation, naturally presents itself to our notice.
It is common in ponds and still waters. It was noticed by Pallas, who
was of opinion that offspring was produced from every part of the body.
De Blainville, on the contrary, was of opinion that offspring was always
produced from the same place; namely, at the junction of that part which
is hollow and that which is not. Van der Höven, the Leyden professor,
agrees with Pallas, and Dr. Johnston's opinions accord with Pallas. The
green Hydra is common all over Europe, inhabiting brooks filled with
herbage--attaching itself particularly to the duckweed of stagnant
ponds, and more especially to the under surface of the leaf. The animal
is reduced to a small greenish tubular sac, closed at one of its
extremities, open at the other, and bearing round this opening from six
to ten appendages, very slender, and not exceeding a line in breadth.
The tubulous sac is the body of the animal (Fig. 87). The opening is at
once its mouth and the entrance to the digestive canal; the appendages,
the tentacula or arms.

[Illustration: Fig. 86. Hydra vulgaris. 1. Hydra with ova and young,
unhatched. 2. Hydra of natural size attached to a piece of floating
wood. 3. Egg ready to burst its shell.]

The Hydras have no lungs, no liver, no intestines, no nervous system, no
heart. They have no organ of the senses, except those which exist in the
mouth and the skin. The arms or branches are hollow internally, and
communicate with the stomach. They are provided with vibratile cells,
furnished with a great number of tuberosities disposed spirally, and
containing in their interior a number of capsules provided each with a
sort of fillet. These threads, which are of extreme tenacity, are thrown
out when the animal is irritated by contact with any strange body. We
may see these filaments wrapping themselves round their prey, sometimes
even penetrating its substance, and effectually subduing the enemy. The
green Hydra has thus a very simple organisation. Nevertheless, it would
be a mistake to say the animal was imperfect, for it possesses
everything necessary for its nourishment and for the propagation of its
species.

[Illustration: Fig. 87. Hydra viridis (Trembley). 1. Hydra magnified,
bearing an embryo ready to detach itself. 2. Animal, natural size. 3.
Bud much magnified. 4. Bud, natural size.]

There are learned men who have composed hundreds of volumes, who have
published whole libraries--naturalists and physicists who have written
more than Voltaire ever penned, but whose names are utterly forgotten.
On the other hand, there are some who have left only two or three
monograms, and yet their names will live for ever. Of this number is the
Genevois, A. Trembley. This writer published in 1744 a "Memoir on the
Fresh-water Polyps." In this little work he recorded his observations
on some of these animals of smallest dimensions. He limited himself even
to two sets of experiments: he turned the fresh-water polyp outside in,
and he multiplied it by cutting it up. These experiments upon this
little creature, which few persons had seen, have sufficed to secure
immortality to his name. Trembley was tutor to the two sons of Count de
Bentinck. He made his observations at the country-house of the Dutch
nobleman, and he had, as he assures us, "frequent occasion to satisfy
himself, in the case of his two pupils, that we can even in infancy
taste the pleasures derivable from the studies of Nature!" Let us hope
that this thought, uttered by a celebrated naturalist, who spoke only
from what he knew himself, may remain engraved on the minds of our
younger readers.

Trembley established by his observations, a thousand times repeated,
that _Hydra viridis_ can be turned outside in, as completely as a glove
may be, without injury to the animal, which a day or two after this
revolution resumes its ordinary functions. Such is the vitality of these
little beings, that what was once the outer surface soon fulfils all the
functions of a stomach, digesting its food, while the intestinal tube
expanding its exterior performs all the functions of an outer surface;
it absorbs and respires. But we shall leave Trembley to relate his very
remarkable experiments. "I attempted," he says, "for the first time to
turn these polyps inside out in the month of July, 1741 but
unsuccessfully. I was more successful the following year, having found
an expedient which was of easy execution. I began by giving a worm to
the polyp, and put it, when the stomach was well filled, into a little
water which filled the hollow of my left hand. I pressed it afterwards
with a gentle pinch towards the posterior extremities. In this manner I
pressed the worm which was in the stomach against the mouth of the
polyp, forcing it to open--continuing the pinching pressure until the
worm was partly pressed out of the mouth. When the polyp was in this
state I conducted it gently out of the water, without damaging it, and
placed it upon the edge of my hand, which was simply moistened, in order
that the polyp should not stick to it. I forced it to contract itself
more and more, and, in doing so, assisted in enlarging the mouth and
stomach. I now took in my right hand a thick and pointless boar's
bristle, which I held as a lancet is held in bleeding. I approached its
thicker end to the posterior extremity of the polyp, which I pressed
until it entered the stomach, which it does the more easily since it is
empty at this place and much enlarged. I continued to advance the
bristle, and, in proportion as it advanced, the polyp became more and
more inverted. When it came to the worm, by which the mouth is kept open
on one side, and the posterior part of the polyp is passed through the
mouth, the creature is thus turned completely inside out; the exterior
superficies of the polyp has become the interior."

The poor animal would be justified in feeling some surprise at its new
situation--disagreeably surprised we may add, for it makes every
imaginable effort to recover its natural position, and it always
succeeds in the end. The glove is restored to its proper form. "I have
seen polyps," says Trembley, "which have recovered their natural
exterior in less than an hour." But this would not have served the
purpose of our experimenter. He wished to know if the polyps thus turned
outside in could live in this state; he had consequently to prevent it
from rectifying itself, for which purpose a needle was run through the
body near the mouth--in other words, he impaled the creature by the
neck.

"It is nothing for a polyp only to be spitted," says Trembley. It is in
fact a very small thing, as we shall see, for thus reversed and spitted
they live and multiply as if nothing had happened.

"I have seen a polyp," says this ingenious experimenter, "turned inside
out, which has eaten a small worm two days after the operation. I have
fed one in that state for more than two years, and it has multiplied in
that condition.

"Having experimented successfully myself, I was desirous of having the
testimony of others capable of forming opinions on the subject. M.
Allamand was persuaded to put his hand to the work, which he did with
the same success I had met with. He has done more, having succeeded in
permanently turning specimens which had been previously turned, and
which continued to live in their re-inverted state; he has seen them eat
soon after both operations; finally, he has turned one for the third
time, which lived some days, but perished without having eaten anything,
although it did not appear that its death was the result of the
operation."

We have said that the _Hydra viridis_ has neither brain, nervous system,
heart, muscular rings, lungs, nor liver; the organs of the
senses--namely, those of sight, hearing, and of smell--have also been
denied them. Nevertheless, they act as if they possessed all these
senses. Oh Nature! how hidden are thy secrets, and how the pride of man
is humbled by the mysteries which surround thee--by the spectacles which
strike his eyes, and which he attempts in vain to explain!

Trembley states that the fresh-water polyps, having no muscular ring,
can neither extend nor contract themselves, nor can they walk. If
touched, or if the water in which they are immersed is suddenly
agitated, they are certainly observed to contract more or less forcibly,
and even to inflect themselves in all directions; and by this power of
extension, of contraction and inflection, they contrive to move from
place to place; but these movements are singularly slow, the utmost
space they have been observed to traverse being about eight inches in
the twenty-four hours.

Painfully conscious of his powers of progression, however, he has found
means of remedying it, and the aquatic snail is his steed; he creeps
upon the shell of a Planorbis, or Limnæa, and by means of this
improvised mount he will make more way in a few minutes than he would in
a day by his own unassisted efforts.

The _Hydra viridis_, although destitute of organs of sight, are
nevertheless sensible of light; if the vase containing them is placed
partly in shade and partly in the sun, they direct themselves
immediately towards the light; they appreciate sounds; they attach
themselves to aquatic plants and other floating bodies. Without eyes,
without brain, and without nerves, these animals lie in wait for their
prey, recognize, seize, and devour it. They make no blunder, and only
attack where they are sure of success. They know how to flee from
danger; they evade obstacles, and fight with or fly before their
enemies. There are, then, some powers of reflection, deliberation, and
premeditated action in these insignificant creatures; their history, in
short, is calculated to fill the mind with astonishment.

Trembley insists much upon the address which the Hydra employs to secure
its prey: by the aid of its long arms, small animals, which serve to
nourish it, are seized, for it is carnivorous, and even passably
voracious. Worms, small insects, and larvæ of dipterous insects are its
habitual prey. When a worm or woodlouse in passing its portals happens
to touch them, the polyp, taking the hint, seizes upon the wanderer,
twining its flexible arms round it, and, directing it rapidly towards
its mouth, swallows it. Trembley amused himself by feeding the Hydra,
while he observed the manner in which it devoured its prey. "When its
arms were extended, I have put into the water a woodlouse or a small
worm. As soon as the woodlouse feels itself a prisoner it struggles
violently, swimming about, and drawing the arm which holds it from side
to side; but, however delicate it may appear, the arm of the polyp is
capable of considerable resistance; it is now gradually drawn in, and
other arms come to its assistance, while the polyp itself approaches its
prey; presently the woodlouse finds itself engaged with all the arms,
which, by curving and contracting, gradually but inevitably approach the
mouth, in which it is soon engulfed." Frédol also notices a singular
fact. "The small worms, even when swallowed by the polyp," he says,
"frequently try to escape; but the ravisher retains them by plunging one
of its arms into the digestive cavity! What an admirable contrivance, by
which the worms are digested while the arm is respected!"

The food of the fresh-water Hydra influences the colour of their bodies
in consequence of the thinness and transparency of their tissues; so
that the reddish matter of the woodlouse renders them red, while other
food renders them black or green, according to its prevailing colour!

The multiplication of these creatures takes place in three different
ways: 1. By eggs. 2. By buds, after the manner of vegetables. 3. By
separation, in which an individual may be cut into two or many segments,
each reproducing an individual.

We shall only say a few words on the first mode of reproduction. The
eggs, according to Ehrenberg, come to maturity in the _H. viridis_ at
the base of the feet, where the visceral cavity terminates. They are
carried during seven or eight days, and determine by their fall the
death of the animal. When the Hydra has laid its eggs, according to M.
Laurent, it gradually lowers itself until it covers them with half its
body, which, spreading out and getting proportionably thin, passes into
the condition of a horny substance, that glues the eggs disposed in a
circle round the body to plants and other foreign substances. She ends
her career by dying in the midst of her ova.

Trembley has studied with great care the mode of reproduction by
budding--a process which seems to prevail in the summer months. The buds
which are to form the young polyp appear on the surface of the body as
little spherical excrescences terminating in a point. A few steps
further towards maturity, and it assumes a conical and finally a
cylindrical form. The arms now begin to push out at the anterior
extremity of the young animal; the posterior extremity by which it is
attached to the mother contracting by degrees, until it appears only to
touch her at one point. Finally, the separation is effected, the mother
and the young acting in concert to produce the entrance of this
interesting young polyp into the world. Each of them take with their
head and arms a strong point of support upon some neighbouring body; and
a small effort suffices to procure the separation: sometimes the mother
charges herself with the effort, sometimes the young, and often both.

When the young polyp is separated from the mother, it swims about, and
executes all the movements peculiar to adult animals. The entrance into
life and maturity takes place with these beings at one and the same
moment. Infancy and youth are suppressed in this little world.

So long as the young polyp remains attached to the mother, she is the
nurse; by a touching change, the young polyp nurses her in his turn. In
short, the stomach of the mother and her young have communication; so
that the prey swallowed by the parent passes partially into the stomach
of her progeny. On the other hand, while still attached to the mother,
the little ones seize the prey, which they share in their turn with
their parent by means of the communication Nature has arranged between
the two organisms.

In the course of his experiments Trembley states another fact still more
remarkable.

Upon a young polyp still attached to its parent he observed a new polyp
or polypule, and upon this unborn creature was another individual. Thus
three generations were appended to the parent, who carried at once her
child, her grandchild, and great-grandchild.

"In observing the young polyps still attached to their parent," says
Trembley, "I have seen one which had itself a little one which was just
issuing from its body; that is to say, it was a mother while yet
attached to its own parent. I had in a short time many young polyps
attached to their parents which had already had three or four little
ones, of which some were even perfectly formed. They fished for woodlice
like others, and they ate them. Nor is this all. I have seen a
mother-polyp which had carried its _third generation_. From the little
one which she had produced issued another little one, and from this a
third."

Charles Bennet, the naturalist of Geneva, says wittily, that a polyp
thus charged with all its descendants constitutes a living genealogical
tree.

We have just spoken of turning polyps inside out! If one of these
creatures is thus operated upon while it bears its young on the surface
of its body, such of them as are sufficiently advanced continue to
increase; although they find themselves in this sudden manner imprisoned
in an internal cavity, they re-issue subsequently by the mouth. Those
less advanced at the moment of reversal issue by little and little from
the maternal sac, and complete their career of development on the
newly-made exterior.

The third and most extraordinary mode of reproduction in the polyps has
been discovered by Trembley in the case of the green Hydra. So surprised
was this naturalist at the strange anomalies which surrounded these
creatures, that he began to have doubts, and gravely to ask the
question, Was this polyp an animal? Is it a plant?

In order to escape from this state of indecision, it occurred to him to
cut a Hydra into pieces. Concluding that plants alone could reproduce
themselves by slips, he waited the result of the experiment for the
conclusion he sought. On the 25th of November, 1740, he cut a polyp into
sections. "I put," he tells us, "the two parts into a flat glass, which
contained water four or five lines in depth, and in such a manner that
each portion of the polyp could be easily observed through a strong
magnifying glass. It will suffice to say that I had cut the polyp
transversely, and a little nearer to the anterior. On the morning of the
day after having cut the polyp, it seemed to me that on the edges of the
second part, which had neither head nor arms, three small points were
issuing from these edges. This surprised me extremely, and I waited with
impatience for the moment when I could clearly ascertain what they were.
Next day they were sufficiently developed to leave no doubt on my mind
that they were true arms. The following day two new arms made their
appearance, and, some days after, a third appeared, and I could now
trace no difference between the first and second half of the polyp which
I had cut."

This is assuredly one of the most startling facts belonging to natural
history. Divide a fresh-water polyp into five or six parts, and at the
end of a few days all the separate parts will be organized, developed,
and form so many new beings, resembling the primitive individual. Let us
add, that the polyp which should thus have lost five-sixths of its body,
the mutilated father of all this generation, remains complete in itself;
in the interval, it has recuperated itself and recovered all its
primitive substance.

After this, if a _Hydra vulgaris_ wishes to procure for itself the
blessings of a family, it has only one thing to do: cut off an arm; if
it desire two descendants, let it cut the arm in two parts; if three,
let it divide itself into three; and so on _ad infinitum_. "Divide one
of the animals," says Trembley, "and each section will soon form a new
individual in all respects like the creature divided." "A whole host of
polyps hewn into pieces," says Frédol, "will be far from being
annihilated." "On the contrary," we may say, in our turn, "its youth
will be renewed, and multiplied in proportion to the number of pieces
into which it has been divided." "The same polyp," says Trembley, "may
be successively inverted, cut into sections, and turned back again,
without being seriously injured."

If a green Hydra is cut into two pieces, and the stomach is cut off in
the operation, the voracious creature will, nevertheless, continue to
eat the prey which presents itself. It gorges itself with the food,
without troubling itself with the loss which it has sustained; but the
food no longer nourishes it, for it merely enters by one opening, passes
through the intestinal canal, and escapes by the other. It realizes
Harleville's pleasantry of M. de Crac's horse, in the piece of that
name, which eats unceasingly, but never gets any fatter.

All these instances of mutilation, resulting in an increase of life, are
very strange. The naturalists to whom they were first revealed could
scarcely believe their own eyes. Réaumur, who repeated many of
Trembley's experiments, writes as follows: "I confess that when I saw
for the first time two polyps forming by little and little from that
which I had cut in two, I could scarcely believe my eyes; and it is a
fact that, after hundreds of experiments, I never could quite reconcile
myself to the sight."

In short, we know nothing analogous to it in the animal kingdom. About
the same period Charles Bennet writes: "We can only judge of things by
comparison, and have taken our ideas of animal life from the larger
animals; and an animal which we cut and turn inside out, which we cut
again, and it still bears itself well, gives one a singular shock. How
many facts are ignored, which will come one day to derange our ideas of
subjects which we think we understand! At present we just know enough to
be aware that we should be surprised at nothing."

Notwithstanding the philosophic serenity which Bennet recommends, the
fact of new individuals resulting from dividing these fresh-water polyps
was always a subject of profound astonishment, and of never-ending
meditation.


SERTULARIADÆ.

All Hydraidæ, with the exception of the Hydra and a few other genera,
are marine productions, varying from a few lines to upwards of a foot in
height, attaching themselves to rocks, shells, sea-weeds, and
corallines, and to various species of shell-fish. Many of them attach
themselves indiscriminately to the nearest object, but others show a
decided preference. _Thuiaria thrya_ attaches itself to old bivalves;
_Thoa halecuia_ prefers the larger univalves; _Antennularia antennina_
attaches itself to coarse sand on rocks; _Laomedea geniculata_ delights
in the broad frond of the tangle; _Plumularia catherina_ attaches itself
in deep water to old shells, corallines, and ascidians, growing in a
manner calculated to puzzle the naturalist, as it did Crabbe, the poet,
who writes of it:--

    "Involved in sea-wrack, here you find a race
    Which science, doubting, knows not where to place;
    On shell or stone is dropp'd the embryo seed,
    And quickly vegetates a vital breed."

_Sertularia pumila_, on the other hand, loves the commoner and coarser
wracks. "The choice," says Dr. Johnston, "may in part be dependent on
their habits, for such as are destined to live in shallow water, or on a
shore exposed by the reflux of every tide, are, in general, vegetable
parasites; while the species which spring up in deep seas must select
between rocks, corallines, or shells." There seems to be a selection
even as to the position on the rocks. According to Lamouroux, some
polyps always occupy the southern slopes, and never that towards the
east, west, or north; others, on the contrary, grow only on these
exposures, and never on the south, altering their position, however,
according to the latitude, and its relation to the Equator.

The _Sertulariadæ_ have a horny stem, sometimes simple, sometimes so
branching that they might readily enough be mistaken for small plants,
their branches being flexible, semi-transparent, and yellow. Their name
is derived from _Sertum_, a bouquet. Each Sertularia has seven, eight,
twelve, or twenty small panicles, each containing as many as five
hundred animalcules; thus forming, sometimes, an association of ten
thousand polyps. "Each plume," says Mr. Lister, in reference to a
specimen of _Plumularia cristata_, "might comprise from four to five
hundred polyps;" "and a specimen of no unusual size now before me," says
Dr. Johnston, "with certainly not fewer cells on each than the larger
number mentioned, thus giving six thousand as the tenantry of a single
polypidom, and this on a small species." On _Sertularia argentea_, it is
asserted, polyps are found on which there exist not less than eighty to
a hundred thousand.

Each colony is composed of a right axis, on the whole length of which
the curved branches are implanted, these being longest in the middle.
Along each of these branches the cells, each containing a polyp, are
grouped alternately. The head of the animal is conical, the mouth being
at the top surrounded by twenty to twenty-four tentacles. These curious
beings have no digestive cavity belonging to themselves; the stomach is
common to the whole colony--a most singular combination, a single
stomach to a whole group of animals! Never have the principles of
association been pushed to this length by the warmest advocates of
communism.

Certain species belonging to the colony, which seem destined to
perpetuate the race, have not the same regular form. Destitute of mouth
and tentacles, they occupy special cells, which are larger than the
others. The entire colony is composed exclusively of individuals, male
or female. "We have traced _Sertularia cupressina_ through every stage
of its development," say Messrs. Paul Gervais and Van Beneden. "At the
end of several days, the embryos are covered with very short vibratile
cells; their movement is excessively slow; then, from the spheroid form
which they take at first, they get elongated, and take a cylindrical
form, all the body inclining lightly sometimes to the right, sometimes
to the left. The vibratile cells fading afterwards, the embryo attaches
itself to some solid body, a tubercle is formed, and the base extends
itself as a disk. At the same time that the first rudiments of the polyp
appear, the disk-like tubercle throws out on its flanks a sort of bud,
and a second polyp soon shows itself; its surface is hardened; the polyp
appears in its turn, and the same process of generation is repeated; a
colony of _Sertulariadæ_ is thus established at the summit of a discoid
projection. At the end of fifteen days the colony, which has been
forming under our eyes, consists of two polyps and a bud, which already
indicates a third polyp. The sea-cypress, as this species is called, is
robust, with longish branches decidedly fan-shaped, the pinnæ being
closer and nearly parallel to each other. The cells form two rows,
nearly opposite, smooth and pellucid. The branches in some specimens are
gracefully arched, bending as it were under the load of pregnant ovaries
which they carry, arranged in close-set rows along the upper side of the
pinnæ. They are found in deep water on the coast of Scotland, and as far
south as the Yorkshire coast and the north of Ireland. The cells, which
are the abode of the polyps, are not always alike in their distribution.
Sometimes they are ranged on two sides, sometimes on one only. Sometimes
they are grouped like the small tubes of an organ, at other times they
assume a spiral form round the stem, or they form here and there
horizontal rings round it."


MEDUSADÆ.

The Medusæ comprehend, not only the animals so designated in the days of
Cuvier under that name, but also the polyps known as _Tubulariadæ_ and
_Campanulariadæ_.

If we walk along the sea shore, after the reflux of the tide, we may
often see, lying immovable upon the sands, disk-like, gelatinous masses
of a greenish colour and repulsive appearance, from which the eye and
the steps instinctively turn aside. These beings, whose blubber-like
appearance inspires only feelings of disgust when seen lying grey and
dead on the shore, are, however, when seen floating on the bosom of the
ocean, one of its most graceful ornaments. These are Medusæ. When seen
suspended like a piece of gauze or an azure bell in the middle of the
waves, terminating in delicate silvery garlands, we cannot but admire
their iridescent colours, or deny that these objects, so forbidding in
some of their aspects, rank, in their natural localities, among the
most elegant productions of Nature. We could not better commence our
studies of these children of the sea than by quoting a passage from the
poet and historian Michelet: "Among the rugged rocks and lagunes, where
the retiring sea has left many little animals which were too sluggish or
too weak to follow, some shells will be there left to themselves and
suffered to become quite dry. In the midst of them, without shell and
without shelter, extended at our feet, lies the animal which we call by
the very inappropriate name of the _Medusa_. Why was this name, of
terrible associations, given to a creature so charming? Often have I had
my attention arrested by these castaways which we see so often on the
shore. They are small, about the size of my hand, but singularly pretty,
of soft light shades, of an opal white; where it lost itself as in a
cloud of tentacles--a crown of tender lilies--the wind had overturned
it; its crown of lilac hair floated about, and the delicate umbel, that
is, its proper body, was beneath; it had touched the rock--dashed
against it; it was wounded, torn in its fine locks, which are also its
organs of respiration, absorption, and even of love.... The delicious
creature, with its visible innocence and the iridescence of its soft
colours, was left like a gliding, trembling jelly. I paused beside it,
nevertheless: I glided my hand under it, raised the motionless body
cautiously, and restored it to its natural position for swimming.
Putting it into the neighbouring water, it sank to the bottom, giving no
sign of life. I pursued my walk along the shore, but at the end of ten
minutes I returned to my Medusa. It was undulating under the wind;
really it had moved itself, and was swimming about with singular grace,
its hair flying round it as it swam; gently it retired from the rock,
not quickly, but still it went, and I soon saw it a long way off."

Of all the zoophytes which live in the ocean there is none more numerous
in species or more singular in their matter, more odd in their form, or
more remarkable in their mode of reproduction, than those to which
Linnæus gave the name of Medusa, from the mythical chief of the Gorgons.

The seas of every latitude of the globe furnish various tribes of these
singular beings. They live in the icy waters which bathe Spitzbergen,
Greenland, and Iceland; they multiply under the fires of the Equator,
and the frozen regions of the south nourish numerous species. They are,
of all animals, those which present the least solid substance. Their
bodies are little else than water, which is scarcely retained by an
imperceptible organic network; it is a transparent jelly, almost without
consistence. "It is a true sea-water jelly," says Réaumur, writing in
1701, "having little colour or consistence. If we take a morsel in our
hands, the natural heat is sufficient to dissolve it into water."

Spallanzani could only withdraw five or six grains of the pellicle of a
medusa weighing fifty ounces. From certain specimens weighing from ten
to twelve pounds, only six to seven pennyweights could be obtained of
solid matter, according to Frédol. "Mr. Telfair saw an enormous medusa
which had been abandoned on the beach at Bombay; three days after, the
animal began to putrefy. To satisfy his curiosity, he got the
neighbouring boatmen to keep an eye upon it, in order to gather the
bones and cartilages belonging to the great creature, if by chance it
had any; but its decomposition was so rapid and complete that it left no
remains, although it required nine months to dissipate it entirely."

"Floating on the bosom of the waters," says Frédol, "the Medusa
resembles a bell, a pair of breeches, an umbrella, or, better still, a
floating mushroom, the stool of which has here been separated into lobes
more or less divergent, sinuous, twisted, shrivelled, fringed, the edges
of the cap being delicately cut, and provided with long thread-like
appendages, which descend vertically into the water like the drooping
branches of the weeping willow."

The gelatinous substance of which the body of the Medusa is formed is
sometimes colourless and limpid as crystal; sometimes it is opaline, and
occasionally of a bright blue or pale rose colour. In certain species
the central parts are of a lively red, blue, or violet colour, while the
rest of the body is of a diaphanous hue. This diaphanous tissue, often
decked in the finest tints, is so fragile, that when abandoned by the
wave on the beach, it melts and disappears without leaving a trace of
its having existed, so to speak.

Nevertheless, these fragile creatures, these living soap-bubbles, make
long voyages on the surface of the sea. Whilst the sun's rays suffice to
dissipate and even annihilate its vaporous substance on some
inhospitable beach, they abandon themselves without fear during their
entire life to the agitated waves. The whales which haunt round the
Hebrides are chiefly nourished by Medusæ which have been transported by
the waves in innumerable swarms from the coast of the Atlantic to the
region of whales. "The locomotion of the Medusæ, which is very slow,"
says De Blainville, "and denotes a very feeble muscular energy, appears,
on the other hand, to be unceasing. Since their specific gravity
considerably exceeds the water in which they are immerged, these
creatures, which are so soft that they probably could not repose on
solid ground, require to agitate constantly in order to sustain
themselves in the fluid which they inhabit. They require also to
maintain a continual state of expansion and contraction, of systole and
diastole. Spallanzani, who observed their movements with great care,
says that those of translation are executed by the edges of the disk
approaching so near to each other that the diameter is diminished in a
very sensible degree; by this movement a certain quantity of water
contained in the body is ejected with more or less force, by which the
body is projected in the inverse direction. Renovated by the cessation
of force in its first state of development, it contracts itself again,
and makes another step in advance. If the body is perpendicular to the
horizon, these successive movements of contraction and dilatation cause
it to ascend; if it is more or less oblique, it advances more or less
horizontally. In order to descend, it is only necessary for the animal
to cease its movements; its specific gravity secures its descent."

It is, then, by a series of contractions and dilatations of their bodies
that the Medusæ make their long voyages on the surface of the waters.
This double movement of their light skeleton had already been remarked
by the ancients, who compared it to the action of respiration in the
human chest. From this notion the ancients called them _Sea Lungs_.

The Medusæ usually inhabit the deep seas. They are rarely solitary, but
seem to wander about in considerable battalions in the latitudes to
which they belong. During their journey they proceed forward, with a
course slightly oblique to the convex part of their body. If an obstacle
arrests them, if an enemy touches them, the umbrella contracts, and is
diminished in volume, the tentacles are folded up, and the timid animal
descends into the depths of the ocean.

We have said that the Medusæ constitute in the Arctic seas one of the
principal supports of the whale. Their innumerable masses sometimes
cover many square leagues in extent. They show themselves and disappear
by turns in the same region, at determinate epochs--alternations which
depend, no doubt, on the ruling of the winds and currents which carry or
lead them. "The barks which navigate Lake Thau meet," says Frédol, "at
certain periods of the year with numerous colonies of a species about
the size of a small melon, nearly transparent--whitish, like water when
it is mixed with a shade of aniseed. One would be tempted to take these
animals at first for a collection of floating muslin bonnets."

The Medusæ are furnished with a mouth placed habitually in the middle of
the neck. This mouth is rarely unoccupied. Small molluscs, young
crustaceans, and worms, form their ordinary food. In spite of their
shape, they are most voracious, and snap up their prey all at one
mouthful, without dividing it. If their prey resists and disputes with
it, the Medusa which has seized it holds fast, and remains motionless,
and, without a single movement, waits till fatigue has exhausted and
killed its victim, when it can swallow it in all security.

In respect to size, the Medusæ vary immensely. Some are very small,
while others attain more than a yard in diameter. Many species are
phosphorescent during the night.

Most Medusadæ produce an acute pain when they touch the human body. The
painful sensation produced by this contact is so general in this group
of animals, that it has determined their designation. Until very
recently all the animals of the group have been, after Cuvier,
designated under the name of Acalephæ, or sea nettles, in order to
remind us that the sensation produced is analogous to that occasioned by
contact with the stinging leaves of the nettle.

According to Dicquemare, who made experiments on himself in this matter,
the sensation produced is very like that occasioned by a nettle, but it
is more violent, and endures for half an hour. "In the last moments,"
says the abbé, "the sensation is such as would be produced by reiterated
but very weak prickings. A considerable pain pervaded all the parts
which had been touched, accompanied by pustules of the same colour, with
a whitish point." "The sea-bladder," says Father Feuillée, "occasions
me, on touching it, a sudden and severe pain, accompanied with
convulsions."

"During the first voyage of the _Princess Louise_ round the world," to
quote Frédol, "Meyen remarked a magnificent physalia, which passed near
the ship. A young sailor leaped naked into the sea, to seize the animal.
Swimming towards it, he seized it; the creature surrounded the person
of its assailant with its numerous thread-like filaments, which were
nearly a yard in length; the young man, overwhelmed by a feeling of
burning pain, cried out for assistance. He had scarcely strength to
reach the vessel and get aboard again, before the pain and inflammation
were so violent that brain fever declared itself, and great fears were
entertained for his life."

[Illustration: Fig. 88. Chrysaora Gaudichaudi.]

The organization is much more complicated than early observers were
disposed to think it. During many ages naturalists were inclined to
imagine, with Réaumur, that the Medusæ were mere masses of organized
jelly, of gelatinized water. But when Courtant Dumeril tried the
experiment of injecting milk into their cavities, and saw the liquid
penetrating into true vessels, he began to comprehend that these very
enigmatical beings were worthy of serious study--the study of subsequent
naturalists, such as Cuvier, De Blainville, Ehrenberg, Brandt,
Makel-Eschscholtz, Sars, Milne Edwards, Forbes, Gosse, and other modern
naturalists, who have demonstrated what richness of structure is
concealed under this gelatiniform and simple structure in the Medusæ; at
the same time they have revealed to us most mysterious and incredible
facts as connected with their metamorphoses.

Among the Medusæ proper, the most common are Aurelia, Pelagia, and
Chrysaora. In the latter, _C. Gaudichaudi_ (Fig. 88), the disk is
hemispherical, festooned with numerous tentacles, attached to a sac-like
stomach, opening by a single orifice in the centre of the peduncle, with
four long, furbelowed, unfringed arms. Gaudichaudi's chrysaora is found
round the Falkland Islands. The disk forms a regular half-sphere, very
smooth, and perfectly concave, forming a sort of canopy in the shape of
a vault. The circle which surrounds it is divided into sections by means
of vertical lines, regularly divided, of a reddish-brown colour, which
forms an edging to the umbrella-like disk. Twelve broad regular festoons
form this edging. From the summit of these lobes issue twelve bundles of
very long, simple, capillary tentacles, of a bright red. The peduncle is
broad and flat, perforated in the middle, to which are attached four
broad foliaceous arms.


RHIZOSTOMA.

The Medusæ which bear the name of _Rhizostoma_ have the disk
hemispherically festooned, depressed, without marginal tentacles,
peduncle divided into four pairs of arms, forked, and dentated almost to
infinity, each having at their base two toothed auricles. Such is
_Rhizostoma Cuvieri_ of Péron (Fig. 89), the disk of which is of a
bluish-white, like the arms, and of a rich violet over its
circumference. This beautiful zoophyte is found plentifully in the
Atlantic, living in flocks, which attain a great size. It is common in
the month of June on the shores of the Saint Onge; in August on the
English coast; and along the strand of every port in the Channel they
are seen in the month of October in thousands, where they lie high and
dry upon the shore, on which they have been thrown by the force of the
winds.

Such also is _R. Aldrovandi_ (Fig. 90), which appears all the year round
in calm weather. It is an animal much dreaded by bathers. It possesses
an urticaceous apparatus, which produces an effect similar to the
stinging-nettle when applied to the skin. If the animal touches the
fisherman at the moment of being drawn from the water, it is apt to
inflame the part and raise it into pustules.

[Illustration: Fig. 89. Rhizostoma Cuvieri.]

_Cassiopea_ and _Cephea_ are two other types belonging to the same
group. In _Cassiopea Andromeda_ (Fig. 91), belonging to the first, the
disk is hemispherical, but much depressed, without marginal tentacles or
peduncle, but with a central disk, with four to eight half-moon-shaped
orifices at the side, and throwing off eight to ten branching arms,
fringed with retractile sucking disks. _Cephea Cyclophora_, Péron (Fig.
92), is another very remarkable form of these strangely-constituted
organisms.

       *       *       *       *       *

Having presented to the reader certain characteristic types of Medusadæ,
we proceed to offer some general remark upon the organization and
functions of these strange creatures. We have, in short, selected these
types because they have been special objects of anatomical and
physiological study to some of our best naturalists.

[Illustration: Fig. 90. Rhizostoma Aldrovandi.]

The Medusæ have no other means of breathing but through the skin. We
remark all over the body of these zoophytes certain cutaneous
elongations, disposed so as to favour the exercise of the breathing
function. Certain marginal fringes of extended surface, as well as the
tentacle, are the special seats of the apparatus. The organs of
digestion also present arrangements peculiar to themselves; the mouth is
placed on the lower part of the body, and is pierced at the extremity of
a trumpet-like tube, hanging sometimes like the tongue of a bell. The
walls of the stomach, again, are furnished with a multitude of
appendages, which have their origin in the cavity of the organ, and
which are very elastic. The stomach, furnished with these vibratile
cells, appears to secrete a juice whose function is to decompose the
food and render it digestible.

[Illustration: Fig. 91. Cassiopea Andromeda (Tilesius).]

In some of the Medusadæ the central mouth is absent altogether. With the
Rhizostoma, for instance, the stomachal reservoir has no inferior
orifice; it communicates laterally with the canals which descend through
the thickness of the arms, and open at their extremities through a
multitude of small mouths. These are the root-like openings from which
the animals derive their name of Rhizostoma, from the Greek words
ῥίζα, root, and στόμα, mouth.

[Illustration: Fig. 92. Cephea Cyclophora.]

The arms of the Rhizostoma are usually eight in number, the free
extremities of each being slightly enlarged: in these arms many small
openings or mouths occur, which are the entrances to so many ascending
canals communicating with larger ones, as the veins do in the higher
animals: the common trunk canal is thus formed, which directs itself to
the stomach, receiving in its way thither all the lateral branches.

A very distinct circulation exists in the Medusæ. The peripheric part of
the stomach suffers the nourishing liquid which has been elaborated in
the digestive cavity to pass: this fluid then circulates through
numerous canals, the existence of which have been clearly traced.

It is also a singular fact, that organs of sense seem to have been
discovered in these Medusæ, which early observers believed to be
altogether destitute of organization. "During my sojourn on the banks of
the Red Sea," says Ehrenberg, in his work on the _Medusa aurita_,
"although I had many times examined the brownish bodies upon the edge of
the disk of the Medusæ, it is only in the month past that I have
recognized their true nature and function. Each of these bodies consists
of a little yellow button, oval or cylindrical, fixed upon a thin
peduncle. The peduncle is attached to a vesicle, in which the microscope
reveals a glandular body, yellow when the light traverses it, but white
when the light is only reflected on it. From this body issue two
branches, which proceed towards the peduncle or base of the brown body
up to the button or head. I have found that each of these small brown
bodies presents a very distinct red point placed on the dorsal face of
the yellow head; and when I compare this with my other observations of
similar red points in other animals, I find that they greatly resemble
the eyes of the Rotifera and Entomostraca. The bifurcating body placed
at the base of the brown spot appears to be a nervous ganglion, and its
branches may be regarded as optic nerves. Each pedunculated eye presents
upon its lower face a small yellow sac, in which are found, in greater
or smaller numbers, small crystalline bodies clear as water." The
presence of a red pigment in very fine grains is an argument in favour
of the existence of visual organs in these zoophytes, for the small
crystals disseminated in the interior of the organ would no doubt
perform the part of refracting light which is produced by crystalline in
the eyes of vertebrated animals. Moreover, it is found that there are
marginal corpuscles analogous to these brown spots in other species of
Medusæ. They are of a palish yellow, or quite colourless, and enclose
sometimes a single, sometimes many calcareous corpuscles. When they are
colourless, some naturalists have rather taken them for ears reduced to
their most simple expression.

The Medusæ are not absolutely destitute of nervous system. We have seen
that they have ganglions, and probably optic nerves. Ehrenberg also
states that they have ganglions at their base, which furnish them with
nervous filaments.

Without entering further into the details of their delicate and
complicated structure, we shall pause briefly on their mode of
reproduction. We shall find here physiological phenomena so remarkable
as to appear incredible, had not the researches of modern naturalists
placed the facts beyond all doubt. "Which of us," says M. de
Quatrefages, "would not proclaim the prodigy, if he saw a reptile issue
from an egg laid in his court-yard, which afterwards gave birth to an
indefinite number of fishes and birds? Well, the generation of the
Medusæ is at least as marvellous as the fact which we have imagined."
Let us note, for example, what takes place with the Rose Aurelia, a
beautiful Medusa, of a pale rose colour, with nearly hemispherical disk,
from four to five inches in diameter, whose edge is furnished with short
russet-brown tentacles; taking for our guide the eloquent and learned
author of the "Metamorphosis in Men and Animals," M. de Quatrefages.

The Medusa, designated under the name of Rose Aurelia, lays eggs which
are characterised by the existence of three concentric spheres. These
eggs are transformed into oval larvæ, covered with vibratile cells,
having a slight depression in front. They swim about for a short time
with great activity, much like the infusoria, which they strikingly
resemble in other respects.

At the end of forty-eight hours the movements decrease. Aided by the
depression already noted, the larvæ attaches itself to some solid body,
fixing itself to it at this point by the assistance of a thick mucous
matter. A change of form soon takes place: it becomes elongated; its
pedicle is contracted, and its free extremity swells into a club-like
shape. An opening soon presents itself in the centre of this extremity,
through which an internal cavity appears. Four little mammals have now
appeared on the edge, which are elongated in the manner of arms. Others
soon follow: these are the tentacles of a polyp: the young infusoria has
become a polyp!

The polyp increases by buds and shoots, just like a strawberry plant,
which throws out its slender stems in all directions, covering all the
neighbouring ground.

The young Medusa lives some time under this form. Then one of the polyps
becomes enlarged and its form cylindrical. This cylinder is divided into
from ten to fourteen superposed rings. These rings, at first smooth,
form themselves into festoons, and separate into bifurcated thongs; the
intermediate lines become channeled. The animal now resembles a pile of
plates, cut round the edges. In a short time each ring is stirred at the
free edge of its fringe: this becomes contractile. The rings are
individualised. Finally, these annular creatures, obscure in their
lives, isolate themselves. When detached, they begin to swim: from that
time they have only to perfect and modify their form. From being flat,
they become concave on the one side and convex on the other. The
digestive cavity--the gastro-vascular canals--become more decided; the
mouth opens, the tentacles are elongated, the floating marginal cirri
become more and more numerous; and now, after all these metamorphoses,
the Medusa appears: it perfectly resembles the mother.


TUBULARIDÆ.

We have already said that recent researches have led to a separation of
a class of animals from the Sertularia, and to their being united with
the Medusæ. Of these creatures we formerly only knew one of the forms,
namely, the polyp form; or, rather, the first stage of it. During their
earliest days they possess a polyp, furnished with tentacles, and a
bell-shaped body. During their medusoid age, they present a central
stomach, with four canals in the form of a cross, and four to eight
tentacles with cirri. The animals constitute the Tubularidæ,
comprehending many genera; among others the Tubularia and Campanularia,
in studying which Van Beneden of Louvain discovered most interesting
facts connected with the subject of alternate generation.

The class of zoophytes ranged among the Tubularia have the power of
secreting an inverting tube of a horny nature, in which the fleshy body
can move up and down, expanding its tentacles over the top. Others of
them give forth buds, each of which takes the form of a polyp, and
these, being permanent, give it a shrub-like or branched appearance; it
is now a compound polyp. The tube is branched, and the orifices from
which the polyps expand usually dilate into cups or cells. This is the
condition of the _Tubulari-campanulariadæ_ groups, which are numerous
round our own coast and in the Channel. The Tubularia are plant-like and
horny, rooted by fibres, tubular, and filled with a semi-fluid organic
pulp; polyps naked and fleshy, protruding from the extremity of every
branchlet of the tube, and armed with one or two circles of smooth
filiform tentacles; bulbules soft and naked, germinating from the base
of the tentacles; embryo medusiform. "Some modern authors," says Frédol,
"assure us that the tree-like form of these polyps is a degraded and
transitory form of the Medusæ. The Medusa originates the polyp, the
polyp becomes a Medusa." _Tubularia ramea_ so perfectly resembles an old
tree in miniature, deprived of its leaves, that it is difficult to
believe it is not of a vegetable origin; it is now a vigorous tree in
miniature, in full flower, rising from the summit of a brown-spotted
stem, with many branches and tufted shoots, terminating in so many
hydras of a beautiful yellow or brilliant red. _T. ramosa_, of a
brownish colour and horny substance, rising six inches, is rooted by
tortuous, wrinkled fibres, with flexible, smooth, and thread-like
shoots, branching into a doubly permeate form. In _T. indivisa_ the
tubes are clustering; its numerous stems are horny, yellow, and from six
to twelve inches in height, about a line in diameter, and marked with
unequal knots from space to space, like the stalk of the oat-straw with
the joints cut off. Their lower extremity is tortuous, attaching itself
readily to shells and stones in deep water, flourishing in deep muddy
bottoms, and upright as a flower, fixed by the tapering root-like
terminations of its horny tube: a flowering animal, having, however,
neither flower nor branch. At the summit of each stem, a double scarlet
corolla is developed of from five to thirty-five petals, in rows, the
external one spreading, those in the interior rising in a tuft; a little
below, the ovarium appears, drooping when ripe like a bunch of
orange-coloured grapes. After a time the petals of the corolla fade,
fall, and die, and a bud replaces them, which produces a new polyp; and
so on. This succession determines the length of the stem. Each apparent
flower throws out a small tube, which terminates it, and each addition
adds one joint more to the axis, which it increases in length.

The Campanulariæ differ considerably from the above, the ends of their
branches, whence the polyps issue, being enlarged into a bell-like
shape, whence their name. _C. dichotoma_ is at once the most delicate
and most elegant of the species. It presents a brownish stem, thin as a
thread of silk, but strong and elastic. The polyps are numerous: upon a
tree eight or nine inches high there may be as many hundreds. _C.
volubilis_ is a minute microscopic species, living parasitically on
corallines, seaweed, and shelled animals. The stem is a capillary
corneous tube, which creeps and twists itself upon its support, throwing
out at alternate intervals a long slender stalk, twisted throughout or
only partially, which supports a bell-shaped cup of perfect
transparency, and prettily serrated round the brim. Dr. Johnston found
the antennæ of a crab so profusely infested with them as to resemble
hairy brushes. It is furnished, according to Hassall, with a delicate
joint or hinge at the base of each little cup--a contrivance designed,
it is imagined, to enable the frail zoophyte the better to elude the
rude contact of the element in which it lives, by allowing it to bend to
a force which it cannot resist.

The Campanulariæ increase by budding, the buds being found in much the
same manner as in the Hydræ. It is a simple excrescence, which, in due
time, takes the form of the branch from which it proceeds. These buds
have their birth at certain distances, and form a new polyp.


SIPHONOPHORA.

Alongside the Medusæ naturalists place certain marine zoophytes which
are equally remarkable for their beauty and for their curious structure,
the latter being so complicated that their true organization long
remained unknown. They were known, until very recently, under the
designation of Hydrostatic Acalephæ, or Hydra-medusæ. They are known in
our days as Siphonophoræ. These inhabitants of the deep are graceful in
form, and are distinguished by their delicate tissues and brilliant
colours. Essentially swimmers, supported by one or many vessels filled
with air--true swimming-bladders, more or less numerous, and of variable
form--they float upon the waves, remaining always on the surface,
whatever may be the state of the sea. They are natural skiffs, and quite
incapable of immersion. The Siphonophoræ form four orders or families;
namely, the _Diphydæ_, double-bell-shaped animals, one fitting into the
cavity of the other; _Physaliadæ_, having large oblong air-vessels and
numerous tentacles of several forms, long, and pendent from one end of
the shell, with a wrinkled crest; _Vilelladæ_, animals stretching over a
cartilaginous plate with a flat body, an oblique, vertical,
cartilaginous crest above, a tubular mouth below, and surrounded by
numerous short tentacles; _Physophora_, consisting of a slender and
vertical axis, terminating in an air-bladder, carrying laterally
swimming-bladders, which lose themselves amongst a bundle of slender
white filaments.


VILELLADÆ.

[Illustration: Fig. 93. Vilella limbosa (Lamarck).]

The Vilellæ assemble together in great shoals; in tropical seas and even
in the Mediterranean they may be seen in fine weather floating on the
surface of the waves. As described by De Blainville, the body is oval or
circular, and gelatinous, sustained in the interior of the dorsal disk
by a solid sub-cartilaginous frame, provided on the lower surface of the
disk with extensible tentacular cirri. The family includes four genera;
namely, _Vilella_, the Holothuria of the Chinese, which the reader will
most readily comprehend from the brief description we shall give of the
Mediterranean Vilella (_V. limbosa_--Fig. 93), which has been very
minutely examined by M. Charles Vogt, of Geneva, from whose work on the
"Inferior Animals of the Mediterranean" our details are borrowed. _V.
spirans_, sometimes called _V. limbosa_, was discovered in the
Mediterranean, between Monaco and Mentone, by Forskahl, who most
erroneously took it for a holothuria. On the upper surface of the animal
is a hydrostatic apparatus, the object of which is to maintain its
equilibrium in the ambient element. This apparatus consists of a shield
and a crest, organs of which M. Vogt gives a very detailed description;
but it is on the under surface that the principal organs of the Vilella
are exhibited. These are not seen when the animal swims, because under
such circumstances the vertical, oblique crest only is visible. The
lower surface is concave, with a sort of mesial nucleus, presenting at
the extremity of a trumpet-like prolongation, whitish and contractile, a
sort of central mouth, surrounded by tentacular cirri, the external row
being much longer than the internal ones. This was formerly thought to
be the stomach of the Vilella. In the present day, this appendage is
known to be the central polyp around which are grouped other whitish and
much smaller appendages, the base being surrounded by little yellow
bunches. These are supposed to be the reproductive organs. Between the
crest and the shield numerous free tentacles present themselves,
vermiform in appearance, cylindrical, and of a sky-blue colour, which
are kept in continual motion.

The Vilella is therefore not an isolated individual, but a group or
colony, in which the individuals intended to be reproductive are the
most numerous, and occupy the inferior parts.

The central polyp, by its size and structure, is distinguishable at the
first glance from all the other appendages of the lower surface of the
body. It is a cylindrical tube, very contractile and pear-shaped,
swollen into a round ball, or considerably elongated. Its mouth is round
and much dilated; it opens in the cylindrical or trumpet part, which is
contained in a sac in the form of elongated fusci, clothed in the
whitish integuments which formed the body of the polyp when perfect. At
the bottom of the sac two rows of openings are observed, which lead to a
vascular network extending over the whole body; the membranous parts,
while affecting various conditions in their arrangement, are
nevertheless in direct communication with all the reproductive
individuals.

It is a general characteristic of all colonies of polypi that the
digestive cavities of the individuals composing them meet and inosculate
in a common vascular system. The Vilellæ present the same conformation.
Only in their case the vascular system is extended horizontally, this
being the essential character of the union of all the individuals
constituting the colony, with the canals common to all, in which the
nourishing fluids circulate, elaborated for all and by all. It is a true
picture of social communism realized by Nature.

The central polyp is alone destined to absorb the food. M. Vogt has
always found in its interior cavity fragments of the shells of
crustaceans, the remains of small fishes; and he has often seen the hard
parts which resist digestion discharged through the trumpet-like
opening. This central polyp nourishes itself and also all the others,
but is itself sterile.

The tentacles are hollow cylinders, completely closed at the extremity.
These are strong muscular tubes of considerable thickness, the interior
of which is filled with a transparent liquid. They are enveloped in a
strong membrane of a deep-blue colour. The epidermis is furnished with
small stinging capsules, formed of a sac with comparatively thick walls.
If this sac is compressed under the microscope it explodes, opening at a
determinate part, and throwing out an apparatus forming a long stiff
filament, which is implanted on a conical channel and surrounded with
points. "I know not," says M. Vogt, "if all this machinery can re-enter
the capsule after it has exploded; but I presume that the animal can
extend itself and withdraw at pleasure. A tentacle of Vilella
sufficiently compressed presents a surface bristling with these cirri,
so as to resemble a brush. The tentacles themselves are in continual
motion, and I have no reason to doubt that the observation of Lesson,
who saw them cover small crustaceans and fishes, may be perfectly true.
These stinging organs doubtless serve the same purpose as with other
animals of the same class; namely, to kill the prey which the tentacles
have enabled them to secure." Thus the Vilellæ have their javelins, as
the Greek and Roman warriors had, and a lasso, as the cavaliers of
Mexico and Texas have.

The reproducing individuals form the great mass of the appendages
attached to the under surface of the Vilella. The form of the
individuals is much more varied, inasmuch as they are extremely
contractile. Nevertheless, they have considerable resemblance to the
corolla of a hyacinth.

These reproductive individuals are, then, at the same time nurses. The
Medusæ originating by budding in the case of those reproductive
individuals, constitute the sexual state of the Vilellæ. They exist, in
short, in two alternate states: the one sexual, producing eggs; in this
state they are isolated individuals of the Medusadæ, which never group
themselves or form colonies: the other aggregate state is non-sexual,
and in it they form swimming colonies, under the special designation of
_Vilellæ_.

The Vilellæ, so called by Lamarck, are found widely diffused in the seas
of Europe, Asia, America, and Australia. One species, _V. limbosa_, is
often taken on the southern coast of England. The animals are also met
with far at sea, and often huddled together in considerable masses, old
and young together.

Such is a brief account of the strange facts to which the careful study
of the lower class of marine animals initiates us. Naturalists range
along with them the _Rataria_ and _Porpita_.

       *       *       *       *       *

The Rataria have the body oval or circular, sustained by a compressed
sub-cartilaginous framework, much elevated, having a muscular, movable,
longitudinal crest below, and provided in the middle with a free
proboscidiform stomach and a single row of marginal tentacular suckers.
De Blainville was inclined to consider the very small animals which
Eschscholtz termed Ratariæ as young and undeveloped _Vilellæ_. M. Vogt
doubts not that the Ratariæ are young Vilellæ which have acquired, by
little and little, the elliptical form, but that the limb is only
furnished at a later period to the reproductive individuals. These
Ratariæ are engendered, according to Vogt, by the naked-eyed Medusæ born
of the Vilellæ, and owe their existence to the eggs produced by these
Medusæ.

       *       *       *       *       *

The Porpitæ constitute, like the Vilellæ, colonies of floating animals
furnished with a cartilaginous, horizontal, and rounded skeleton, but
they are destitute of crest or veil. The body is circular and depressed,
slightly convex above, with an internal circular cartilaginous support,
having the surface marked by concentric striæ crossing other radiating
striæ, the upper surface being covered by a delicate membrane only. The
body is concave below; the under surface is furnished with a great
number of tentacles, the exterior ones being longest, and also with
small cilia, each terminating in a globule, which sometimes contains
air; the interior tentacles are shorter, simple, and fleshy. In the
centre of these tentacula is the mouth, in form of a small proboscis,
leading to a simple stomach surrounded by a somewhat glandular
substance. The editors of the last edition of the "Règne Animal" only
mention one species--_P. Gigantea_, a native of the Mediterranean and
other warm seas, of a beautiful blue colour. Lamarck gives four species.
De Blainville and others consider with Cuvier that they are only
varieties, which Eschscholtz reunites under one species. In Fig. 94 we
have represented _P. Pacifica_ (Lesson), the disk of which is twelve
lines in diameter, without comprehending the tentacles. This disk is
finely radiated on the under surface with a brilliant argentine nacre.
The membranous fold which surrounds it is cut into, leaving light and
perfectly straight festoons. It is of a clear celestial blue colour, and
very transparent. The tentacles are much compressed, very thin and
cylindrical, of a light blue, and the glands are of an indigo blue
colour. All the reproductive individuals, which are placed in the lower
part of the body, are of a perfect hyaline white.

[Illustration: Fig. 94. Porpita pacifica (Lesson).]

This beautiful Porpita was discovered by Lesson on the Peruvian coast,
where it occurs in swarms closely packed on the surface of the sea. "Its
manner of life," says Lesson, "is perfectly analogous to that of the
Vilella. Their locomotion on the sea is purely passive, at least in
appearance. Their disk laid flat on the surface upon the water-line,
leaves them to float freely and in a horizontal direction, the irritable
arms hanging all round them."


PHYSOPHORA.

[Illustration: Fig. 95. Physophora hydrostatica (Forskahl).]

This family includes the _Physophora_, properly so called, the
_Agalina_, and the _Stephanomina_, for the history of which we are
indebted to the curious observations of M. Vogt. Fig. 95 is a
representation of _Physophora hydrostatica_, after M. Vogt's memoir. We
see that the animal is composed of a slender vertical axis, terminating
in an aërial bladder, carrying laterally certain vesicles, known as
swimming-balls, which terminate in a bundle of whitish slender threads.

The aërial bladder is brilliant and silvery, punctured with red spots.
The swimming-bladders are encased in a transparent and somewhat
cartilaginous capsule, which is continued into the common median trunk,
the latter being rose-coloured, hollow, and very contractile; in short,
it presents very delicate muscular fibres, which expand themselves on
the external fan of the capsule, and is closed on all sides.

The swimming-bladders are of a glass-like transparency, and of a firm,
compact tissue. They are attached obliquely and alternately upon a
common axis, presenting an exterior curvature, a round opening,
furnished with a fine, muscular, and very contractile limb, and arranged
like the iris of the eye. Their power of resistance is increased by
certain horny hollow threads, which are in direct communication with the
cavity of the vertical trunk, and have their origin in a common circular
canal.

"The animal," says Vogt, "is enabled to guide itself in any direction by
means of the swimming apparatus or air-bags. These, on opening, are
filled with water, which is again ejected in the contractile movement,
for their movements may be compared to that of the umbrella of the
Medusæ. It is the violent expulsion of this liquid which enables the
animal to advance diagonally through the water, a kind of motion which
is the consequence of its organization; for where both rows of air-bags
are working in the direction of the axis of the trunk, the organism will
incline to the side which works most, but always in such a manner that
the aërial vesicle will be borne forward."

In its lower parts the trunk expands, becomes flat, and winds itself in
a spiral. It is hollow, and encloses a transparent viscous liquid, in
which very small granules are observed, which appear to be the result of
digestion. This disk is attached to three different sorts of appendages;
we shall first address ourselves to the tentacles.

These form a crown or bundle of vermiform appendages, of a reddish
colour, over an inch in length, and which are kept continually in
motion: these are formed of a glass-like cartilaginous substance; they
are conical tubes, closed on all parts except at the point where the
tentacle is attached to the disk. Their cavity is filled with the
granulous liquid already mentioned. On the under surface of the disk,
and to the inside of these tentacles, the polyps and fishing-lines are
attached.

[Illustration: Fig. 96. P. hydrostatica, with a portion of the disk,
three polyps, and reproductive clusters attached.]

The anterior part of the polyp is formed of a glass-like substance,
which changes its form in the most varied and surprising manner. It
bears a roundish mouth at its summit. In its posterior part the polyp
presents a straight hollow stem, of reddish colour; but near to this red
stem we find a thick tuft of cylindrical appendages, from the middle of
which springs the extensible and contractile filaments which Vogt calls
the _fishing-lines_ (fil pêcheur), and of which he has given the
following very strange account:

"Each of these appendages consists of an assemblage of cylindrical tubes
somewhat resembling and analogous to a filament of confervæ. All these
tubes are traversed by a continuous canal, which originates in the
internal cavity of the stem of the polyp. Each fragment of the line is
capable of a prodigious extent of elongation and contraction; but where
completely drawn back the pieces fold themselves up somewhat in the
manner of a pocket foot-rule. It is to the combined effect of
contraction and the unfolding of the pieces that these lines owe the
marvellous changes of length which they present." In Fig. 96 are
represented the polyps and fishing-lines of _P. hydrostatica_, with a
portion of the disk and two pairs of reproductive clusters.

In this figure it will be observed that each fragment or joint has
implanted, near the articulation, a secondary line, which bears the
stinging organ. Each of these filaments consists of three parts: a
straight stem, muscular, contractile, and hollow, the cavity of which
communicates with that of the trunk which carries it; a middle part, a
sort of tube containing, in a considerable internal cavity, a
transparent liquid; finally, an inflated stinging organ, which
terminates the apparatus. This last is egg-shaped, and consists
internally of a hyaline substance of cartilaginous consistence, in the
interior of which we find a great cavity, which opens from within, near
the base of the capsule; to the inside of this cavity a second muscular
sac is attached all round the opening of the capsule, in such a manner
that the opening leads directly into the cavity of the sac. This cavity
conceals in its interior a long filament usually rolled up in a spiral,
as illustrated in Fig. 97, where the two urticant capsules of the
stinging apparatus of _Physophora hydrostatica_ are represented, one of
them being a section, magnified by twelve diameters. This spirally
rolled-up filament consists of a large quantity of very small, hard,
sabre-shaped, corpuscular bodies, supported the one against the other,
and having their points turned inwards. These objects Vogt terms
"_urticant sabres_:" the extremity of the filament consists of curved
corpuscles, larger, of a brownish yellow, very strong, and with a double
point. M. Vogt had also opportunities of observing the action of these
stinging capsules. He has seen them burst naturally, and he has also
obtained artificially the same result. In the former case the filament
issues from the opening left at the base of the capsule with a sort of
explosion. "The use," he says, "of the fishing-lines" becomes evident
when we see a Physophora in repose in a vase large enough for its full
development; then it takes a vertical position; the lines elongate
themselves more and more, by unfolding one by one the secondary lines
with stinging capsules, and the Physophora now resembles a flower posed
upon a tuft of roots, with extremely long and delicate rootlets
reaching the bottom of the vase. But in the case of the Physophora the
living roots are in continual motion. Each line is elongated,
foreshortened, and contracted in a thousand ways. The least movement of
the water causes the stinging capsules to be suddenly drawn up, the
lines hauled in most rapidly being those near the crown of tentacles.
This continuous play of the lines has no other object than to attract
the prey destined to feed the polyp, and we cannot find any better
comparison for them than the fishing-lines to which they have been
compared. The moment that some small microscopic medusæ, larvæ, or
crustaceans come within the sphere of those redoubted lines, it is at
once surrounded, seized, and led with irresistible force towards the
mouth of this polyp by a gentle and gradual contraction of the line; the
stinging organs, complicated as we have seen them to be in the
Physophora, thus serve the same purpose as the stinging organs
disposed on the arms of the Hydræ, or on the external surface of the
tentacles and prolific polyps of the Vilellæ.

[Illustration: Fig. 97. Offensive apparatus of Physophora hydrostatica.]

Can there be any animal form more graceful than _Agalma rubra_, which is
reproduced in Plate VII. from Vogt's Memoir? This beautiful creature is
common in the Mediterranean, on the coast near Nice, from November till
the month of May. Towards the middle of December Vogt found nearly fifty
individuals in the space of an hour, opposite to the Port of Nice, all
following the same current, a prodigious quantity of Salpæ, Medusæ, and
small Pteropodean Mollusks accompanying them.

[Illustration: Plate VII.--Agalma rubra, three-fifths natural size.]

"I know nothing more graceful," says Vogt, "than this Agalma as it
floats along near the surface of the waters, its long, transparent,
garland-like lines extended, and their limits distinctly indicated by
bundles of a brilliant vermilion red, while the rest of the body is
concealed by its very transparency; the entire organism always swims in
a slightly oblique position near the surface, but is capable of steering
itself in any direction with great rapidity. I have had in my possession
some of these garlands more than three feet in length, in which the
series of air-bags measured more than four inches, so that in the great
vase in which I kept them the column of swimming bags touched the
bottom, while the aërial vesicle floated on the surface. Immediately
after its capture the columns contracted themselves to such a point that
they were scarcely perceptible, but when left to repose in a spacious
vase, all its shrunken appendages deployed themselves round the vase in
the most graceful manner imaginable, the column of swimming-bladders
remaining immovable in their vertical position, the air-bags at the
surface, while the different appendages soon began to play. The polyps,
planted at intervals along the common trunk of rose-colour, began to
agitate themselves in all directions, taking a thousand odd forms; the
reproductive individuals, like the tentacles, were contracting and
twisting themselves about like so many worms; the tentacles were
stirred, the ovarian clusters began to dilate and contract, the
spermatic air-bells agitated the waters with their umbrellas, like the
Medusæ; but what most excited my curiosity, was the continuous action of
the fishing-lines, which continued to unroll and contract in a most
surprising manner, retiring altogether sometimes with the utmost
precipitation. All who have witnessed these living colonies detach
themselves reluctantly from the strange spectacle, where each polyp
seems to play the part of the fisherman who throws his line, furnished
with baited hooks, withdrawing it when he feels a nibble, and throwing
again when he discovers his disappointment. These efforts continue in
full vigour for two or three days, and I have succeeded sometimes in
feeding them with the small crustaceans which swarm on our coasts."

Of the "personelle" of these colonies a few words will not be misplaced.
The common axis of the _Agalma_ is a hollow muscular tube, the length of
which may be three feet, and its breadth an eighth or tenth of an inch;
it is traversed by a double current of granulous liquid; at its summit
is the aërial vesicle; beneath are the swimming vessels. These are
disposed along the trunk in a double series, attaining sometimes the
number of sixty; their structure is analogous to the same organs in the
Physophora.

In examining the posterior portion of the trunk, traversing polyps are
observed at intervals, whose base is surrounded by a cluster of reddish
grains, each of which is armed with a _line_, and with its surrounding
filament, terminating in a tendril of a red vermilion colour, which is a
perfect arsenal of offensive and defensive arms. There we find
"_sabres_" of divers sizes, and poniards of various forms, the whole
constituting a truly formidable stinging apparatus.

These warlike engines, these arms of attack and defence with which man
surrounds himself, Nature has freely bestowed on these little creatures
with which the ocean swarms in some places. It might be said that, after
having created these graceful creatures to ornament and decorate the
depths of the ocean, the Creator was so pleased with His work that He
furnished them with arms for their protection and defence against all
attacks from without.

Among these creatures we may note the pretty _Apolemia contorta_ of
Milne Edwards (Fig. 98), which also inhabits the Mediterranean, and
particularly the coast of Nice, and is no less admirable in its
structure than _Agalma rubra_. This elegant species is often met with in
the Gulf of Villafranca, near Nice, and has been figured and described
by Milne Edwards, Charles Vogt, and also by M. de Quatrefages, who asks
the reader "to figure to himself an axis of flexible crystals, sometimes
more than a mètre (forty inches), all round which are attached, by means
of long peduncles or foot-stalks equally transparent, some hundreds of
bodies, sometimes elongated, sometimes flat, and formed like the bud of
a flower. If we add to this garland of pearls of a vivid red colour, an
infinity of fine filaments, varying in thickness, and give life and
motion to all these parts, we have even now only a very slight and
imperfect idea of the marvellous organism." The air-bells in _Apolemia
contorta_ consist of a mass having the form of an elongated egg cut in
the middle. They are arranged in a vertical series of twelves, and the
axis which supports them is terminated by the aërial vesicle. This axis
is always arranged in a spiral form, even in its greatest expansion, is
of a fine rose tint, and flattened into the form of a ribbon; it is
marked in all its length with asperitics or hollow dimples, in which the
filamental appendages originate.

[Illustration: Fig. 98. Apolemia contorta, one-third natural size (Milne
Edwards).]

The nursing polyps have been called _poboscidiferous_ organs by Mr.
Milne Edwards, who has studied them carefully. They are rendered
conspicuous at a glance by the bright-red colour of their digestive
cavity and their extreme dilatability. At the base of their stems the
very delicate filaments called fishing-lines are attached, which are
furnished with a multitude of stinging tendrils of a reddish colour.
These tendrils slightly resemble those of the Agalmæ, and the sabre-like
weapons are not wanting.

[Illustration: Fig. 99. Apolemia contorta, magnified 12 times.]

[Illustration: Fig. 100. Apolemia contorta, reproductive pair, magnified
12 times.]

Between the nursing polyps are placed in pairs the reproductive
individuals, having the form of an elongated tube very dilatable, and
closed at the free end. They have, then, no mouth! Milne Edwards calls
these "vesicular appendages," and M. Koelliker, tentacles. The buds
arranged at the base of each prolific individual vary; but, according to
M. Vogt, they are always there in pairs--a male and female at the base
of each stem. Figs. 99 and 100 represent the colony we have endeavoured
to describe, 99 being the nursing individual of _Apolemia contorta_
magnified twelve times, 100 representing the reproductive pair under the
same magnifying power.


THE DIPHYDÆ.

We have seen that the _Physophora_, the _Agalma_, and the _Apolemia_
have for the use of the colony a vast number of swimming vesicles and a
terminal aërial vesicle. It is much the same in the _Prayæ_ or Diphydæ.
In this family a great number of natatory vesicles are connected with
the terminal aërial vesicle, as in Fig. 101, _Praya diphys_. This
species is widely diffused in the sea which bathes the Nicean coast, but
it is very difficult to procure perfect specimens. M. Vogt found
fragments more than three feet long which swam on the surface, and was
in its state of contraction not more than a finger's length. This
species has been met with at Porta della Praya and at San Yago, one of
the Cape de Verde islands.

[Illustration: Fig. 101. Praya diphys (Blainville).]

The colony of the Praya presents two great locomotive bell shaped
masses, between which the common trunk is suspended, and to which it can
retire. This cylindrical trunk, which is thin and transparent, carries
from space to space certain groups very exactly circumscribed and
individualised. Each of these groups consists of a nursing polyp, having
its fishing-line with a special floating air-bladder, a reproductive bud
male or female, and a protecting casque enveloping the whole.

Another species having a great resemblance to the _Praya_ is _Galeolaria
aurantiaca_ (Plate VIII.), or orange Galeolaria, which is represented on
the opposite page, borrowed from the fine "Memoir of the Inferior
Animals of the Mediterranean," by Carl Vogt. Here we find only two great
floating bladders placed at each extremity of a common trunk, and
serving the purpose of a locomotive apparatus to the whole colony. This
trunk carries in like manner polyps placed at regular intervals forming
isolated groups, provided each with its protecting plates. But there is
no special swimming apparatus for each of these groups. Moreover, each
colony is either male or female.


PHYSALIA.

Let us finally note among the Siphonophoræ a zoophyte which has
attracted great attention, and has been described under many names.
Sailors call it the sea-bladder, from its resemblance to that organ; it
is also known as the Portuguese man-of-war, from its fancied resemblance
to a small ship as it floats along under its tiny sail. Naturalists
after Eschscholtz call it _Physalia utriculus_, from the Greek word
φυσαλὶϛ, a bubble, and utriculus from its stinging powers. It was
long thought that the Physalia was an isolated individual. But,
according to recent researches, they form, like the species already
described, an animal republic.

Let us imagine a great cylindrical bladder dilated in the middle,
attenuated and rounded at its two extremities, of eleven or twelve
inches in length, and from one to three broad. Its appearance is glassy
and transparent, its colour an imperfect purple, passing to a violet,
then to an azure above. It is surmounted by a crest, limpid and pure as
crystal, veined with purple and violet in decreasing tints. Under the
vesicle float the fleshy filaments, waving and contorted into a spiral
form, which sometimes descend perpendicularly like so many threads of
celestial blue. Sailors believe that the crest which surmounts the
vesicle performs the office of a sail, and that they tell the navigator
"how the wind blows," as they say. With all respect to the sailors, the
bladder-like form, with its aërial crest, is only a hydrostatic
apparatus, whose office is to lighten the animal, and modify its
specific gravity. Mr. Gosse thinks otherwise, however.

[Illustration: Plate VIII.--Galeolaria aurantiaca. (Vogt.)]

"This bladder," says Gosse, in his "Year by the Sea-side," "is filled
with air, and therefore floats almost wholly on the surface. Along the
upper side, nearly from end to end, runs a thin edge of membrane, which
is capable of being erected at will to a considerable height, fully
equal at times to the entire width of the bladder, when it represents an
arched fore-and-aft sail, the bladder being the hull. From the bottom of
the bladder, near the thickest extremity, where there is a denser
portion of the membrane, depends a crowded mass of organs, most of which
take the form of very slender, highly contractile movable threads, which
hang down into the deep to a depth of many feet, or occasionally of
several yards.

"The colours of this curious creature are very vivid; the bladder,
though in some parts transparent and colourless, and in some specimens
almost entirely so, is in general painted with richest blues and purple,
mingled with green and crimson to a smaller extent, these all being, not
as sometimes described, iridescent or changeable, but positive colours
independent of the incidence of light, and, for the most part,
possessing great depth and fulness. The sail-like, erectile membrane is
transparent, tinted towards the edge with a lovely rose-pink hue, the
colours arranged in a peculiar fringe-like manner. When examined
anatomically, the bladder is found to be composed of two walls of
membrane, which are lined with cilia, and have between them the
nutritive food which supplies the place of the blood. Besides this, the
double membrane is turned in or inverted like a stocking prepared for
putting on; and thus there is a bladder within a bladder, both having
double walls; the inner (_pneumatocyst_) much smaller than the outer
(_pneumatophone_), and contracted at the point where it is turned into
the almost imperceptible orifice. The inner sends up closed tubular
folds into the crest, which, being arrested by the membranous walls of
the outer sac, give to the sail that appearance of vertical wrinkles
which is so conspicuous."

When it is filled with air the body is almost projected out of the
water. In order to descend it is necessary to compress itself or dispel
the air, in part, for the centre of gravity in the animal is displaced
according as the air is in the vesicle or in the crest. When the last is
distended it rises out of the water, and becomes nearly vertical; in
short, it then becomes a sort of sail. The floating appendages beneath
the body are of divers kinds. Some of these are reproductive
individuals; some are nurses; some are tentacles; finally, there are
organs designated under the name of _Sondes_ by French naturalists;
probes or suckers, we may call them, forming offensive and defensive
arms truly formidable; for these elegant creatures are terrible
antagonists. Dutertre, the veracious historian of the Antilles, relates
the following: "This 'galley' (our Physalia), however agreeable to the
sight, is most dangerous to the body, for I can assert that it is
freighted with the worst merchandise which floats on the sea. I speak as
a naturalist, and as having made experiments at my own personal cost.
One day, when sailing at sea in a small boat, I perceived one of these
little 'galleys,' and was curious to see the form of the animal; but I
had scarcely seized it, when all its fibres seemed to clasp my hand,
covering it as with birdlime, and scarcely had I felt it in all its
freshness (for it is very cold to the touch) when it seemed as if I had
plunged my arm up to the shoulder in a caldron of boiling water. This
was accompanied with a pain so strange that it was only with a violent
effort I could restrain myself from crying aloud."

Another voyager, Leblond, in his "Voyage aux Antilles," relates as
follows: "One day I was bathing with some friends in a bay in front of
the house where I dwelt. While my friends fished for sardines for
breakfast, I amused myself by diving, in the manner of the native
Carribeans, under the wave about to break; having reached the other side
of one great wave, I had gained the open sea, and was returning on the
top of the next wave towards the shore. My rashness nearly cost me my
life: a Physalia, many of which were stranded upon the beach, fixed
itself upon my left shoulder at the moment the wave landed me on the
beach. I promptly detached it, but many of its filaments remained glued
to my skin, and the pain I experienced immediately was so intense that I
nearly fainted. I seized an oil flask which was at hand, and swallowed
one half, while I rubbed my arm with the other: this restored me to
myself, and I returned to the house, where two hours of repose relieved
the pain, which disappeared altogether during the night."

Mr. Bennett, who accompanied the exploring expedition under Admiral
Fitzroy, as naturalist, ventured to test the powers of the Physalia. "On
one occasion," he says, "I tried the experiment of its stinging powers
upon myself, intentionally. When I seized it by the bladder portion, it
raised the long cables by muscular contraction of the bands situated at
the base of the feelers, and, entwining the slender appendages about my
hand and finger, inflicting severe and peculiarly pungent pain, it
adhered most tenaciously at the same time, so as to be extremely
difficult of removal. The stinging continued during the whole time that
the minutest portion of the tentacular remained adherent to the skin. I
soon found that the effects were not confined to the acute pungency
inflicted, but produced a great degree of constitutional irritation: the
pain extended upwards along the arm, increasing not only in extent but
in severity, apparently acting along the course of the absorbents, and
could only be compared to a severe rheumatic attack. The pulse was
accelerated, and a feverish state of the whole system produced: the
muscles of the chest, even, were affected; the same distressing pain
being felt on taking a full respiration as obtains in a case of acute
rheumatism. The secondary effects were very severe, continuing for
nearly three-quarters of an hour; the duration being probably longer in
consequence of the time and delay occasioned by removing the tentacula
from the skin, to which they adhered, by the aid of the stinging
capsules, with an annoying degree of tenacity. On the whole being
removed, the pain began to abate; but during the day a peculiar numbness
was felt, accompanied by an increased temperature in the limb on which
the sting had been inflicted. For some hours afterwards the skin
displayed white elevations or weals on the parts stung, similar to those
resulting from the poison of the stinging nettle. The intensity of the
pain depends in some degree upon the size and consequent power of the
creature. After it has been removed from the water for some time, the
stinging property, although still continuing to act, is found to have
perceptibly diminished. I have observed, also, that this irritative
power is retained for some weeks after the death of the animal, in the
vesicles of the cables, and even linen cloth which has been used for
wiping off the adhering tentacles, when touched, still retained the
pungency, although it had not the power of producing such violent
constitutional irritation."

The question has been much agitated, without being positively resolved,
whether the Physalia are venomous or not: if they can kill or make sick
the man or animal which swallows them. Listen to the opinions of M.
Ricord-Madiana, a physician of Guadaloupe, who made direct experiments
with a view to settling the question. "Many inhabitants of the
Antilles," he says, "say that the 'galleys' are poisonous, and that the
negroes make use of them, after being dried and powdered, to poison both
men and animals. The fishermen of the islands also believe that fish
which have swallowed them become deleterious, and poison those that eat
them, a prejudice which has been adopted by many travellers, and has
even found its way into scientific books. We can state as the result of
direct experiment, that though the 'galley,' will burn the ignorant hand
which is touched by its tentacles, when dried in the sun and pulverized,
it becomes mere grains of dead matter, producing no effect whatever upon
the animal economy."

On the other hand, we read in P. Labat's Voyage, vol. ii. p. 31, "that
the bécune should not be eaten without some precaution, for this fish
being extremely voracious, greedily devours all that comes within its
reach in and out of the water, and it often happens that it meets and
swallows 'galleys,' which are very caustic, and a violent poison. The
fish does not die, but its flesh absorbs the venom, and poisons those
who eat it." "There is every reason to believe," says M. Leblond, in the
work already quoted, "that the sardine, as well as many other species of
fish, after having ate the tentacles of the 'galley,' acquires a
poisonous quality. Supping at an auberge on one occasion, with other
persons, a bécune was served up, of which gastronomers are very fond,
and which is usually perfectly harmless: five persons partook of it, and
immediately afterwards exhibited every symptom of being poisoned. This
was manifested by a burning heat in the region of the stomach. I bled
two of them: one was cured by vomiting; one other would take nothing but
tea and some culinary oil. The colic continued during the night, and had
disappeared in the morning, but he entertained so great a horror of
water, that during the remainder of the voyage a glass of it presented
to him made him turn pale." M. Leblond concludes, from this and other
facts, that the fishes which eat the Physalia become a poison for those
who eat them, although it does not appear that he had any evidence of
the fish having ate the "galley," or any other poison.

"Let us report our own experiments," continues M. Ricord-Madiana.

"I. I had placed a 'galley' in the sun, in order to dry and pulverize
it. A nest of ants were there, who devoured the whole of it. Now, many
persons in the islands think that these insects will not touch venomous
fishes.

"II. Another 'galley,' which I had left on the table in my laboratory,
was attacked by a number of great flies, who deposited their eggs there;
these were duly hatched, and the larvæ fed on the decomposed zoophyte.

"III. On the 12th of July, 1823, I saw on the sands in the bay between
Saint Mary and La Goyave, at Guadaloupe, many Physalia recently cast
ashore. Having a dog with me, with the assistance of my servant, I made
him swallow the freshest of them, with all its filiform tentacles,
pushing it down his throat, while my servant held his mouth open; five
minutes after, the dog exhibited symptoms of great pain on the edges of
its lips; it foamed at the mouth and rubbed it in the sand, or upon the
grass, leaping about, passing its paws over its jaws, and exhibiting
every symptom of excessive pain. I mounted my horse, and, in spite of
its sufferings, the poor animal followed me as it was wont. After twenty
minutes, when its sufferings seemed over, I had a piece of bread which I
gave it, and it ate it with appetite, swallowing it without any
difficulty; it only seemed to feel the pain on the edges of its mouth:
it was well enough all day, and had evacuations which gave no indication
that the Physalia had any influence over the digestive organs. Next day,
and the day following, it was as well as usual, exhibiting no signs of
inflammation either in the mouth or throat.

"IV. On the 20th of the same month, I took two 'galleys' on the
sea-shore and cut them in pieces; then, with a spoon, I had them forced
down the throat of a puppy, which still sucked its mother; this strong
dose of Physalia had no effect upon it, the tentacles having probably
been surrounded by the fleshy parts of the animal in dividing it, so as
not to touch the mouth: it seems probable, therefore, that the internal
mucus is capable of subduing the irritation, which is so distressing
when applied to membranes exposed to the external air. We swallow some
things with impunity, which we could not support in the mouth if the
burning substance remained there.

"V. I have also procured many 'galleys' since these experiments, and
having placed them in a glass tube, left them to dry and had them
pulverized; twenty-five grains of this powder administered to a very
young dog produced no deleterious effects. Twice this quantity
administered to a young cat produced no more, nor has this surprised me;
for, if the fresh animal has no poisonous properties, how can it be
supposed that drying the zoophyte can have increased its poisonous
properties, if it really possesses them? On the contrary, it is more
reasonable to suppose that, by desiccation, the deleterious principle
from any animal, whether _Physalia_ or _Holothuria_, should lose
infinitely in its principle by evaporation, and other changes that heat
and air produce in the process of drying.

"VI. I have had a 'galley' cut into pieces, and got a fat young chicken
to swallow them. It caused no inconvenience. Three hours after, I had
the chicken killed and roasted; then I ate it, and made my servant eat
it too. Neither of us experienced any inconvenience from it, a certain
proof that it is not from eating Physalia that the fish becomes
poisonous.

"VII. I put twenty-five grains of powdered _Physalia_ in a little
'bouillon;' I swallowed the dose without the least fear, and I felt no
inconvenience from it."

After these experiments, which are certainly quite conclusive, what are
we to think of the story related of a certain M. Tébé, the managing
partner of a house in Guadaloupe, who fell a victim to his cook, who is
said, after having sought in vain to poison him with the rasping of his
nails, which he had spread carefully over the roasted fish daily served
up for dinner, determined, seeing that he had signally failed by other
means, to put into his soup a pulverized Physalia. An hour after his
repast, this gentleman appeared in the burgh of Lamantin, at a little
distance from his habitation, and, while entering the city with some
friends, he was seized with violent pains in the stomach and intestines,
racking him as if by the most corrosive poison. His illness increased
until the next day, when he died, under the most excruciating pains. On
examination, the stomach and intestines were found to be violently
inflamed and corroded, as if he had been poisoned with arsenic, and I
have no doubt that it was with this poison, or some other corrosive
substance, that M. Tébé really was poisoned. The negroes never make
known the substance with which they commit a poisoning; they confess all
but the truth, which they are sworn never to reveal--the means they
employ, so far as the poisoning material is concerned, are never
communicated by confession.

[Illustration: Fig. 102. Physalia utriculus (Eschscholtz).]

The habits of the Physalia are still imperfectly known, but among the
many strange forms of brilliant colour and elegant contour, which swarm
in the warmer parts of the ocean, "none," says Gosse, "take a stronger
hold on the fancy of the beholder; certainly none is more familiar than
the little thing he daily marks floating in the sun-lit waves, as the
ship glides swiftly by, which the sailors tell him is the Portuguese
man-of-war. Perhaps a dead calm has settled over the sea, and he leans
over the bulwarks of the ship scrutinizing the ocean-rover at leisure,
as it hastily rises and falls on the long, sluggish heavings of the
glassy surface. Then he sees that the comparison of the stranger to a
ship is a felicitous one, for at a little (Fig. 102) distance it might
well be mistaken for a child's mimic boat, shining in all the gaudy
painting in which it left the toy-shop.

"Not unfrequently, one of these tiny vessels comes so close alongside,
that, by means of the ship's bucket, with the assistance of a smart
fellow who has jumped into the 'chains' with a boat-hook, it is
captured, and brought on deck for examination. A dozen voices are,
however, lifted, warning you by no means to touch it, for well the
experienced sailor knows its terrible powers of defence. It does not now
appear so like a ship as when it was at a distance. It is an oblong
bladder of tough membrane, varying considerably in shape, for no two
agree in this respect; varying also in size, from less than an inch to
the size of a man's hat. Once, on a voyage to Mobile, when rounding the
Florida reef, I was nearly a whole day passing through a fleet of these
little Portuguese men-of-war, which studded the smooth sea as far as the
eye could reach, and must have extended for many miles. They were of all
sizes within the limits I have mentioned."

Generally, there is a conspicuous difference between the two extremities
of the bladder, one end being rounded, the other more pointed, or
terminating in a small knob-like swelling or beak-shaped excrescence,
where there is a minute orifice; sometimes, however, no such excrescence
is visible, and the orifice cannot be detected.

"That wonderful river," continues Mr. Gosse, in his nervous, eloquent
style, "with a well-defined course through the midst of the
Atlantic--that Gulf Stream--brings on its warm waters many of the
denizens of tropical seas, and wafts them to the shores on which its
waves impinge. Hence it is that so many of the proper pelagic creatures
are from time to time observed on the coasts of Cornwall and Devon. The
Portuguese man-of-war is among them, sometimes paying its visit in
fleets, more commonly in single stranded hulks. Scarcely a season passes
without one or more of these lovely strangers occurring in the vicinity
of Torquay. Usually," he adds in a note, "in these stranded examples the
tentacles and suckers are much mutilated by washing on the shore. The
fishermen who pick them up always endeavour to make a harvest of their
capture, not by selling, but by making an exhibition of them."

The Physalia seem to be gregarious in their habits, herding together in
shoals. Floating on the sea between the tropics in both oceans, they may
be seen now carried along by currents, now driven by the trade-winds,
dragging behind them their long tentacular appendages, and conspicuous
by their rich and varied colouring, from pale crimson to ultramarine
blue. "Certainly," says Lesson, "we can readily conceive that a poetical
imagination might well compare the graceful form of the Physalia to the
most elegant of sailing-vessels, even if it careened to the wind under a
sail of satin, and dragged behind it deceitful garlands which struck
with death every creature which suffered itself to be attracted by its
seductive appearance."

If fishes have the misfortune to come in contact with one of these
creatures, each tentacle, by a movement as rapid as a flash of light, or
sudden as an electric shock, seizes and benumbs them, winding round
their bodies as a serpent winds itself round its victim. A Physalia of
the size of a walnut will kill a fish much stronger than a herring. The
flying fish and the polyps are the habitual prey of the Physalia. Mr.
Bennett describes them as seizing and benumbing them by means of the
tentacles, which are alternately contracted to half an inch, and then
shot out with amazing velocity to the length of several feet, dragging
the helpless and entangled prey to the sucker-like mouths and
stomach-like cavities concealed among the tentacles, which he saw filled
while he looked on. Dr. Wallach thinks Mr. Bennett must have been
mistaken in what he saw; "because he has observed that in a great number
of instances the Physalia is accompanied by small fishes, which play
around and among the depending tentacles without molestation. He has in
so many cases seen this, and even witnessed the actual contact of the
fishes with the tentacles, with no inconvenience to the former, that he
too hastily concludes that the urticating organs are innocuous."
"Surely," says Gosse, "the premises by no means warrant such an
inference. There is no antagonism between the two series of facts
witnessed by such excellent observers; the venomous virulence of these
organs has been abundantly proved by many naturalists, myself among the
number, and Mr. Bennett to his cost, as already narrated. We can only
suppose that the injection of the poison is under the control of the
Physalia's will, and the impunity of the bold little fishes is
sufficiently accounted for."

Among the Physalia captured on our coast, one was obtained at Tenby, by
Mr. Hughes, who has given a report of the capture, in which he mentions
a circumstance as "normal," which excited Mr. Gosse's curiosity; it was
said to be accompanied by "its attendant satellites, two _Vilellæ_. In
reply to his inquiries", Mr. Hughes says, "My authority for the
association of the Vilella with Physalia is Jenkins, the collector of
Tenby, who was attending me when it was found. The Physalia was taken by
me first; and, while I was admiring it, I noticed that Jenkins continued
his search for something. Immediately afterwards he came up with the
Vilella in his hand, at the same time stating they were generally found
with the Portuguese man-of-war. As I had found him very honest and
truthful in his dealings with me, I accepted his information as
correct."


CTENOPHORA.

We have now reached the last class of polyps; those, namely, which
Cuvier designates _Hydrostatic Acalepha_, and which De Blainville calls
the _Ciliobranchiá_. The body of these polyps presents marginal fringes
furnished with vibratile cilia, which are swimming organs. Moreover, as
these vibratile fringes are inserted directly over the principal canal,
in which the nourishing fluid circulates, they ought necessarily to
concur in the act of respiration, by determining the renewal of the
water in contact with the corresponding portion of the tegumentary
membrane.

The class may be divided into three orders or families, namely, _Beröe_,
_Callianirea_, and _Cestea_.

The creatures belonging to these three orders swarm in the deep sea;
they often appear quite suddenly, and in vast numbers, in certain
localities.

[Illustration: Fig. 103. Beros Forskahli (Edwards).]

The _Beröes_ of Forskahl have been studied with great care by Mr. Milne
Edwards. They inhabit the Gulf of Naples, and other parts of the
Mediterranean; the sailors of Provence call them Sea-cucumbers. The body
(Fig. 103), cylindrical in form, is of a pale rose colour, thickly
studded with small reddish spots, so numerous as to appear entirely
punctured with them. It presents eight blue sides, with very fine
vibratile cilia, which by their reflection produce all the colours of
the rainbow. The substance of the body is gelatinous, its appearance
glass-like; its form varies according as the animal is in motion or
repose. Sometimes it swells up like a ball; sometimes it reverses
itself, so as to resemble a bell; at others it is elongated and
cylindrical; at its lower extremity it presents a large mouth; at its
upper extremity is found a small nipple, having at its base a spherical
point of a reddish colour, enclosing many crystalloid corpuscles, which
rest upon a sort of nervous ganglion, whose physiological function is
not very well determined. A vast stomach, considering its size, occupies
the whole interior of the body of the Beröe: the circulation is also
much developed in this zoophyte. The circulating apparatus contains a
moving fluid charged with a multitude of circular, colourless globules,
which flows from a vascular ring round the mouth towards the summit of
the body; in the interior are eight superficial canals, which flow under
the ciliated sides, and redescend by two much deeper canals; but the
Beröes have no heart. _Beröe ovata_ is a beautiful species, seldom
exceeding three inches and a half in length, and two and a half in its
larger transverse diameter; is described by Browne, in his "Jamaica," as
"of an oval form, obtusely octangular, hollow, open at the larger
extremity, transparent, and of a firm gelatinous consistence; it
contracts and widens with great facility, but is always open and
expanded when it swims or moves. The longitudinal radii are strongest in
the crown or smallest extremity where they rise from a very beautiful
oblong star, and diminish gradually from thence to the margin, each
being furnished with a single series of short, slender, delicate
appendages, or limbs (cilia), that move with great celerity in all
directions, as the creature pleases to direct its flexions, and in a
regular accelerated succession from the top to the margin. It is
impossible to express the liveliness of the motions of those delicate
organs, or the beautiful variety of colour which rise from them to play
to and fro in the rays of the sun; nor is it easy to express the speed
and regularity with which the motions succeed each other from one end of
the rays to the other." "The grace and beauty which the entire apparatus
presents in the living animal," says Gosse, "or the marvellous ease and
rapidity with which it can be alternately contracted, extended, and bent
at an infinite variety of angles, no verbal description can sufficiently
treat. Fortunately the creature is so common in summer and autumn on all
our coasts, that few who use the surface can possibly miss its capture.
It is worthy of a poet's description, which it has received:--

    'When first extracted from her native brine,
    Behold a round, small mass of gelatine,
    Or frozen dewdrop, void of life and limb;
    But round the crystal goblet let her swim
    'Midst her own elements; and lo! a sphere
    Banded from pole to pole; as diamond clear,
    Shaped as bard's fancy shapes the small balloon,
    To bear some sylph or fay beyond the moon.
    From all her bands see lurid fringes play,
    That glance and sparkle in the solar ray
    With iridescent hues. Now round and round
    She whirls and twirls; now mounts, then sinks profound.'"

          DRUMMOND.

Besides the Beröe, naturalists place the Cydippa, which is frequently
confounded with the former. The Cydippæ are globulous or egg-shaped,
furnished with eight rows of cilia, corresponding with as many sections
more or less distinct, and terminated by two long filiform tentacles
issuing from the base of the zoophyte and fringed on the sides. "It is,"
says Gosse, "a globe of pure colourless jelly, about as big as a small
marble, often with a wart-like swelling at one of its poles, where the
mouth is placed. At the other end there are minute orifices, and between
the two passes the stomach, which is flat or wider in one diameter than
the other." _Cydippe pileus_, found abundantly in the spring on the
Belgian coast, is so transparent that it is scarcely visible in the
water, where it seems like living, moving crystal. _C. densa_, which
abounds in the Mediterranean, is of a crystalline white, with rows of
reddish cirrhi, terminating in two tentacles, much longer and coloured
red; it is about the size of a hazel-nut, and phosphorescent. Within the
clear substance of the _Cydippe_, on each side of the stomach, there is
a capacious cavity, which communicates with the surface, and within each
cavity is fixed the tentacle, of great length and very slender, which
the animal can at pleasure shoot out of the orifice and suffer to trail
through the water, shortening, lengthening, twisting, twining, or
contracting it into a tiny ball at will, or withdrawing it into its
cavity, short filaments being given off at intervals over the whole
length of this attenuated white thread-like apparatus, each of which can
also be lengthened or shortened, and coiled individually. These proceed
only from one side of the thread-like tentacle, although, at a casual
glance, they seem to proceed now from one side, now from the other.


CALLIANIRA.

The Callianira form a sort of connecting link between the _Beröes_
and the _Cestidæ_. Their bodies are smooth and regular,
vertically-elongated, compressed on one side and as if lobated on the
other; in substance they are gelatinous, hyalin, and tubular, obtuse at
both extremities, with buccal openings between the prolongations of the
side, and two pair of conical appendages resembling wings, capable of
expansion, on the edges of which two rows of vibratory cilia are ranged.
A great transversal opening presents itself at one of the extremities, a
small one at the other. The animal is furnished with two branching
tentacles, but without cilia.


CESTIDÆ.

In _Cestum_, or Venus's Girdle, as it is vulgarly called, we have a
long, gelatinous, ribbon-like body, fine, regular, and very short, but
much extended on each side, while the edges are furnished with a double
row of cilia; the lower surface is also furnished with cilia, but much
smaller in size and number. On the middle of the lower edge is the
mouth, opening into a large stomach. This alimentary canal runs across
the middle of its length, and from it extends, as in the Medusæ, a
series of gastric canals, which carry the nutriment into all parts of
the body. There are many species of Cestum; among them the best known is
_C. veneris_ (Fig. 104), which is found in the Mediterranean,
particularly in the sea which bathes the coast of Naples and Nice, where
the fishermen call it the _sabre de mer_--sea-sabre. This curious
zoophyte unwinds itself on the bosom of the waters, like a scarf of
iridescent shades. It is the scarf of Venus traversing the waves, under
the fiery rays of the sun, which has coloured it with a thousand
reflections of silver and azure blue.

[Illustration: Fig. 104. Cestum veneris (Lesueur).]



CHAPTER IX.

ECHINODERMATA.

"Ultra magis pisces et Echinos æquora celent."--_Hor. Ep._


In their "Natural History of the Echinodermata," Messrs. Hupé and
Dujardin divide this vast natural group into five orders or families,
namely: 1, _Asteroïdæ_, which includes the true star-fishes; 2,
_Crinoïdæ_, stone lilies, calcareous, stem composed of movable pieces;
3, _Ophiuræ_, having the disk much depressed, the rays simple, and
furnished with short stems; 4, _Echinidæ_, comprehending the animals
known as sea-eggs, or sea-urchins, distinguished by their rounded form
and absence of arms; 5, _Holothuroïdæ_, with soft lengthened cylindrical
body, covered with scattered suckers.

The Echinodermata, from the Greek words ἐχῖνοϛ, rough, and
δέρμα, skin; indicating an animal bristling with spines like
the hedgehog's. They are animals sometimes free, sometimes attached by
a stem, flexible or otherwise, and radiating, that is, presenting an
appearance more or less regular in all its parts, after the manner of
a circle or star, its form being globular, egg-shaped, cylindrical, or
like a pentagonal plate; or, lastly, like a star, with more or less
elongated branches, which secrete either in all their tissues or only
in the integument very numerous symmetrical calcareous plates of solid
matter, sometimes forming an internal skeleton or regular shell covered
with a more or less consistent skin, often pierced with holes, from
which the feet or tentacula issue; they are frequently furnished with
appendices of various kinds, such as prickles, scales, &c.

The organization of the Echinodermata is the most perfect of all the
zoophytes, serving as a transition between them and animals of more
complicated frame. They have a digestive and vascular system, and a
muscular system is almost always present; in short, they have internal
or external respiratory organs, and a rudimentary nervous system has
been detected in many of the species. The nutritive system is very
simple, presenting in most of the family a single orifice in the centre
of the lower surface of the body, destitute of teeth, performing the
functions both of mouth and anus. De Blainville says that "the liver is
apparent and rather considerable in the star-fishes, forming bunches
occupying the whole circumference of the stomach, and extending to the
cavities of the appendages where these exist." The mouth and gullet is
admirably adapted for securing the testaceous mollusks and other
substances on which they feed.

Reproduction in the Echinodermata appears to be monoecious. Ovaries are,
as far as is known, the only organs of generation. They vary in number
in different species. The sexes are usually separate: the young are
produced by eggs, the embryo of which undergo important metamorphoses.
Immediately after birth, the young asteriæ have a depressed and rounded
body, with four club-shaped appendages or arms at their anterior
extremity. When they are a little more developed, papillæ may be
observed on the upper surface, in fine radiating rows: after twelve days
the fine rays begin to increase, and after eight days more two rows of
feet, or tentacula, are developed under each ray, which assist in the
locomotion of the animal by alternate elongation and contraction,
performing also the office of suckers. Like most other zoophytes, they
have the power of reproducing parts of their bodies which may have been
accidentally destroyed.


ASTERIAS, OR STAR-FISHES.

As to the animal which commonly and sometimes scientifically bears the
name of Star-fish, in walking on the sea-shore at low tide, your eyes
have often seen this strange creature half buried in the sand. It is so
regular and geometrical in its form that it has more the appearance of
being the production of man's hand than of a creation which breathes and
moves. The Divine Geometrician who created it never realised a creature
more regularly finished in shape, or more perfectly harmonious in
symmetry.

The _star-fish_ has five perfectly equal arms. They resemble a cross of
honour, which has five branches. The _star of the brave_, the _star of
honour_--these somewhat trivial words recall, nevertheless, the
resemblance which exists between the two objects; doubtless, man has
here taken Nature for his copy. It must, however, be remarked that,
though five is the general number of lines in the star-fish, this number
is not constant; it varies with different genera, species, and even with
individuals. The connection of the arms with the disk presents equally
remarkable differences. In the genus _Culcita_, the disk is so much
developed that it constitutes, so to speak, the entire animal, whilst
the arms form only a slight protuberance upon its circumference. In the
genera _Luidia_, on the contrary, the disk is reduced to minimum, whilst
the arms are of great length and very slender.

[Illustration: Fig. 105. Asterias rubens (Lamarck).]

The colours of the _star-fish_ vary greatly; they vary from a
yellowish-grey, a yellow-orange, a garnet-red, to a dark violet, as
their name indicates.

_Star-fishes_ are exclusively and essentially beings of the sea; they
are never seen in fresh water; they dwell amongst the submarine herbage,
seeking for sandy coasts; they generally are found at moderate depths,
but there are some species which are found at the great depth of a
hundred and fifty fathoms.

Asterias are met with in almost every sea and under all latitudes, but
they are most numerous and their forms are more richly varied in the
seas of tropical regions. There are about a hundred and forty species
described.

[Illustration: Fig. 106. Asterias aurantiaca (Lamarck).]

The body of the Asteria is supported by a calcareous envelope composed
of juxta-posed pieces at once various and numerous. The number of these
pieces is estimated at more than eleven thousand in the Red Sea
Star-fish (_Asterias rubens_, Fig. 105), a species very common in
Europe. The body of the _Asterias rubens_ is likewise furnished with
spines, granules, and tubercules, the shape, number, and disposition of
which serve to characterise the genera and the species.

Another species, _Asterias aurantiaca_, will give an exact idea of the
general type of animals of this order. This zoophyte, which is
represented in Fig. 106, is common in the northern seas; it has five
rather long arms, furnished with spines which are of an orange
colour--hence its name. When we see one of these animals stranded upon
the shore, it appears to be entirely destitute of all power of
progression. But the _star-fish_ is not always immovable; it is provided
with an apparatus for locomotion, which appears to serve at the same
time the purposes of respiration; for nature is not sparing in her gifts
to the least organized beings; she bestows upon them feet, with
respiratory organs, or lungs, which have the power of locomotion.

The muscular system, as already stated, is almost always present in the
Echinodermata, but the organs of locomotion are very various, the
principal being the membranous tubes usually termed feet, or ambulacra,
which issue from the ambulacral apertures; but besides these, the rays
themselves are movable, and in animals which are free to move from place
to place these are used for the purpose. Thus in the common star-fish
the rays may be bent towards the upper or lower surface of the disk, so
as to facilitate its advance either in water over small spaces or up the
vertical face of rocks. These ambulacra are very numerous, disposed in
rows along the under surface of the rays; thus in _A. aurantiaca_ there
are two simple rows of feet attached to each ray, and the vesicular part
is deeply cleft into two lobes; while in _A. rubens_ (Fig. 105) there
are two double rows on each ray, and each foot has an undivided vesicle.

Each of these ambulacra consists of two parts, an internal and generally
vesicular portion placed within the body, and a tubular portion outside,
projecting from the surface through an aperture in the skin or shell,
the tube being closed at the extremity, and terminating in a sucker,
usually in the form of a disk slightly depressed in the centre. The feet
are thus muscular fleshy cylinders, hollow in the centre, and very
extensible; by means of them the animal draws itself forward. The foot
is extended by the contraction of its internal vesicle, which forces the
fluid into the hollow tube, or, where the vesicle is wanting, by
projecting the fluid into the tube by a communicating vessel. The
tubular part is thus distended and elongated, and again retracts itself
by means of its muscular fibres, by which action the fluid is forced
back into the interior. In progression the animal extends a few of its
feet, attaches its suckers to the rocks or stones, then, by shortening
its feet, it draws its body forward. The progression of the Asterias is
thus very slow, and so regular that only the closest observation enables
the spectator to discover the movement which produces it. Like the
movements of the hands of a watch, the eye cannot quite follow it. When
an obstacle presents itself--if, for example, a stone comes in its
way--it raises one of the rays in order to obtain a point of support,
then a second ray, and, if necessary, a third,--and thus the animal
creeps over the stone with as much ease as if it walked over the smooth
sands. In the same way the animal creeps up perpendicular rocks, which
is accomplished by means of these ambulacra and suckers. Frédol says:
"If an Asteria is turned upon its back it will at first remain
immovable, with its feet shut up. Soon, however, out come the feet, like
so many little feelers; it moves them backward and forward, as if
feeling for the ground; it soon inclines them towards the bottom of the
vase, and fixes them one after the other. When it has a sufficient
number attached the animal turns itself round. It is not impossible,
whilst walking on the sea-shore, to have the pleasure of seeing one of
these star-fishes walking upon the sand. A day rarely passes without one
of them being thrown upon the strand by the tide, and then abandoned by
the retreating waters. Generally they are left dead; this is not always
the case, however; they are sometimes only benumbed. Place them in a
vase full of sea-water, or simply in a pool on the shore, and you will
sometimes see them recover from this death-like condition, and execute
the curious movements of progression which we have described." The
motions of an Asterias thus saved form a very curious spectacle.

The mouth of this animal is situated on the lower surface of the disk.
At this point the constitutive pieces of the carapace leave a circular
space, covered by a fibrous resistant membrane, pierced at the centre by
a rounded opening. This opening is sometimes armed with hard papillæ,
which play the part of teeth. The mouth almost directly abuts on the
stomach, which is merely a globular sac, filling nearly all the central
portion of the visceral cavity.

"Thus," says Mr. Milne Edwards, "in _Asteracanthion glacialis_ the
stomach is globulous, but imperfectly divided into two parts by a fold
of its internal membrane; the first chamber, thus limited, appears to be
more especially devoted to the transformation of the elementary matter
into a liquid paste, which passes, in small portions, into the upper
chamber. This is continued upward through a small intestine, and
communicates laterally with five cylindrical prolongations, which each
divide themselves again into two much elongated tubes, furnished with a
double series of hollow branches, each terminating in a cul-de-sac."
These organs advance into the interior of the rays or arms of the
Asterias.

Imagine, then, an animal bearing digestive tubes in its arms--the same
organ serving for digestion and progression. What lessons in economy
does not the study of nature teach us! The products of digestion find an
absorbent surface of great extent in the rays of the Asterias. They
ought necessarily to pass rapidly from it into the circumjacent
nourishing fluid.

The star-fishes are very voracious; they even attack mollusks which are
covered with shells. M. Pouchett mentions having taken eighteen
specimens of _Venus_ intact, each being six lines in length, from the
stomach of one large Asterias which he dissected upon the shores of the
Mediterranean. It is now even said that the star-fishes eat many
oysters.

Ancient naturalists were not ignorant that the star-fish was capable of
eating oysters; but they believed that they waited for the moment when
the bivalve would open its valves to introduce one of their rays into
the opening. They imagined that having thus put one foot into the
other's domicile, they soon put four, and finished by reaching and
devouring the savoury inhabitant of the shell. Modern observations have
modified the ideas of former naturalists upon this point. In order to
obtain possession of and swallow an oyster, it appears that the
star-fish begins its approaches by bringing its mouth to the closed
edges of the oyster-shell; this done, with the assistance of a
particular liquid which its mouth secretes, it injects a few drops of an
acrid or venomous liquid into the interior of the oyster-shell, which
forces it to open its valves. An entrance once obtained, it is not long
before it is invaded and ravaged. Professor Rymer Jones gives another
explanation of the transaction. According to this naturalist the oyster
is seized between the rays of his ravisher, and held under his mouth by
the aid of his suckers; the Asteria then inverts its stomach, according
to the professor, and envelopes the entire oyster in its inmost
recesses, while, doubtless, distilling a poisonous liquid. The victim is
thus forced to open its shell, and becomes the prey of the enemy which
envelopes it.

Whatever may be the modes of procedure employed by the star-fish, it is
now clearly ascertained, however incredible the fact may at first
appear, that it swallows oysters in the same manner as is practised at
the oyster-shop.

This little being, formed of five arms and without any other apparent
member, accomplishes a work which man is quite unable to execute--it
opens an oyster without an oyster-knife.

If reasoning man had no other means of nourishment than oysters, and was
without a knife to open them, it is very certain that with all his
genius he would be puzzled how to get at the inaccessible and savoury
bivalve so obstinately closed against him. The star-fish devours dead
flesh of all kinds; their sole occupation is to feed themselves, and
they keep up an incessant and active chase after all sorts of corrupt
animal matter. The Asterias thus perform in the bosom of the sea the
same part that certain birds and insects play on shore; they are its
scavengers, and feed their bodies upon the carcases of animals which, if
abandoned to the action of the elements, would become a cause of
infection.

In the same manner that certain animals render the air healthy, the
Asterias help, on a considerable scale, to keep the sea which shelters
them in a pure and healthy state. Zoologists are not agreed upon the
manner in which respiration operates on the star-fishes. Nevertheless
they think that the principal part in this phenomenon devolves upon the
subcutaneous branchiæ which in each ray constitute two double series of
bladders. The function of circulation is equally unknown. The vascular
apparatus is sufficiently developed in this zoophyte, and appears to
have for its centre an elongated canal with muscular walls, which may
with justice be honoured with the name of heart. A little ring
surrounding the oesophagus, and from which issue certain delicate white
chords, which are prolonged into the furrows of the arms, presents us
with all that can be designated a nervous system in the star-fishes.
Among organs of sense we may mention, as the apparatus of touch, the
_tentacular ambulacra_, as well as those which are disseminated upon the
dorsal surface of the disk. The eyes are considered to be certain
bright red points which are situated at the extremity of the arms and on
the under surface--a most singular position for the organs of sight. The
eyes must, besides, be very imperfect, for they possess no crystalline
lens. Ehrenberg insists upon the existence of eyes in some species,
attributing the function to those red spots, however; while Rymer Jones
attributes the indications in which this originates to an extremely
delicate sense of touch in the star-fishes. Professor Edward Forbes,
while he admits the existence of ganglions in the nervous system to be
extremely doubtful, seems, by the frequent use of the terms eye and
eyelids, to admit that the specks in question are visual organs; the
weight of authority inclines therefore to Ehrenberg's view, that if not
eyes in the strict sense of the term, they serve the purposes of vision,
modified and adapted to the wants of the animal.

The star-fishes have distinct sexes, with individual differences; their
eggs, which are round and reddish, undergo curious phases of
development. They produce little worm-like creatures, covered with
vibratile hairs, like the infusoria, which swim about with great
vivacity; these little creatures are subject to considerable changes. In
the year 1835 M. Sars described, under the name of _Bipinnaria
asterigera_, an enigmatical animal resembling a polyp from the arms at
one extremity of the body, while the other terminated in a tail,
furnished with two fins; but it was chiefly remarkable as having an
Asterias attached to the extremity which carried the arm. He expressed
an opinion, which was soon placed beyond any doubt, that this
_bipinnaria_ was an Asterias in its course of development. The egg
becomes a sort of infusoria, the infusoria becomes a _bipinnaria_, and
this produces the Asterias. In short, the Bipinnaria does not become an
Asterias by any metamorphoses analogous to that so well known amongst
insects--the butterfly, for example--but becomes, so to speak, the
foster-mother or nurse to the Bipinnaria. The larva is large, and it is
at the cost of a very small internal rudiment of this larva that the
Asterias is developed: the Asterias robs the larva of its stomach and
intestines, and turns it into a visceral apparatus for its own use. But
the Asterias makes itself a mouth of any of the pieces most remote from
the primitive mouth of the larva. Thus the Bipinnaria divides itself; it
gives its stomach and intestines, and keeps its oesophagus and mouth,
and it can live several days after the Asterias is detached from it.

Can any one imagine the existence of a being with only a mouth and
oesophagus, which has neither stomach nor intestines, because another
animal has possessed itself of them for its own use? The study of the
lower animals abounds in surprises of this kind. It is a chain of
unforeseen facts; of natural impossibilities; of realized points
necessarily reversing all notions obtained in the study of beings which
have a higher place in the animal scale. The history of the star-fishes
would be incomplete were we to omit mentioning the most remarkable
traits of their organisation with which naturalists are acquainted. The
animals exhibit in the highest degree the vital phenomena of
dismemberment and restoration, that is to say, of the faculty of
reconstructing organs which they have lost. These arms, the structure of
which is so complicated, and which protect such important organs, may be
destroyed by accident. The animal troubles itself little at this
mutilation: if he loses an arm it disquiets him but little; another is
immediately procured. We often see in our collections of Asterias
specimens wanting in symmetry because they have been taken before the
new members which are in process of development have attained their
definite length. Professor Rymer Jones mentions an instance of
redintegration very complete and most curious. This naturalist had an
isolated ray of Asterias which he had picked up; at the end of five days
he observed that four little rays and a mouth had been produced; at the
end of a month the old ray was completely destroyed, and this apparently
useless fragment had been replaced by a new being, quite perfect, with
four little symmetrical branches. This faculty of reproducing organs,
which we have noted in describing the fresh water polyps, the sea
anemone, &c., exists also in many other zoophytes, but in none more
strikingly than in the Asterias. But a still more startling fact remains
to be mentioned: one more strange and more mysterious, for it does not
belong to the physical or organic order, but appears to belong to the
moral world. The star-fishes commit suicide! Certain of these animals
appear to escape from dangers which menace them by self-destruction.
This power of putting an end to existence we only find on the highest
and lowest steps of the animal scale. Man and the star-fishes have a
common moral platform, and it is that of self-destruction! This power of
dismemberment, however, seems to be confined to the _Ophiocoma_ and
_Luidia_--at least, it is only carried out to its full extent in these
generæ.

Mysteries of Nature, who can sound your depths? Secrets of the moral
world, what being but God has the privilege of comprehending you? A
large species of Star-fish (_Luidia fragillissima_), which inhabits the
English seas, has this instinct of suicide to a great extent. The
following account by Professor Edward Forbes of an attempt to capture a
Luidia gives a good illustration of its powers. "The first time that I
took one of these creatures," the professor says, "I succeeded in
placing it entire in my boat. Not having seen one before, and being
ignorant of its suicidal powers, I spread it out on a rowing bench, the
better to admire its form and colours. On attempting to remove it for
preservation, to my horror and disappointment I found only an assemblage
of detached members. My conservative endeavours were all neutralised by
its destructive exertions; and the animal is now badly represented in my
cabinet by a diskless arm and an armless disk. Next time I went to
dredge at the same spot I determined not to be cheated out of my
specimen a second time. I carried with me a bucket of fresh water, for
which the star-fishes evince a great antipathy. As I hoped, a Luidia
soon came up in the dredge--a most gorgeous specimen. As the animal does
not generally break up until it is raised to the surface of the sea, I
carefully and anxiously plunged my bucket to a level with the dredge's
mouth, and softly introduced the Luidia into the fresh water. Whether
the cold was too much for it, or the sight of the bucket was too
terrific, I do not know; but in a moment it began to dissolve its
corporation, and I saw its limbs escaping through every mesh of the
dredge. In my despair I seized the largest piece, and brought up the
extremity of an arm with its terminal eye, the spinous eyelid of which
opened and closed with something exceedingly like a wink of derision."

The mind remains confounded before such spectacles, and we can only say,
with Mallebranche, "It is well to comprehend clearly that there are some
things which are absolutely incomprehensible."

This is doubtless the reason that in collections of natural history we
rarely find star-fishes, and especially the Luidia, entire; the moment
the animal is seized by fisherman or amateur, in its terror or despair
it breaks itself up into small fragments. To preserve them whole they
must be killed suddenly, before they have time to be aware of their
danger. For this purpose, the moment they are drawn from the sea they
must be plunged into a vase of cold fresh water; this saltless liquid
is instant death to these creatures, which in this condition perish
suddenly before they have time to mutilate themselves. The star-fish is
a curious ornament in our natural history collections, but in this state
they represent very imperfectly the elegance and particular grace of
this curious type. To understand the star-fishes, they must be seen in
an aquarium, where we can admire the form, figure, movements, and
manners of these marvellous beings.

The Asterias are the planets of the sea. It may be said that heaven,
reflected during the night on the silvery surface of the ocean, let fall
some of those stars into its depths which decorate the resplendent
vault.


CRINOÏDEA.

We quoted the maxim of Linnæus in the earlier pages of this volume, that
Nature makes no leaps. Nature proceeds by means of insensible
transitions, rising by degrees from one organic form to another. Most of
the animals hitherto described are immovably fixed to some solid object;
at least, such is their condition in the adult state. We are about to
describe zoophytes free of all fetters; animals "which walk in their
strength and liberty."

Between zoophytes fixed to the soil, like the corals, gorgons, and
aggregate zoophytes, such as sea-urchins and holothurias, Nature has
placed an intermediate race, namely, the Crinoïdea, a class of zoophytes
which are attached to a rock by a sort of root armed with claws, having
a long flexible stem, which enables them to execute movements in the
circle limited only by the length of this stem, just as the ox or goat
in our paddocks is confined by its tether to the space circumscribed by
the length of its rope.

Let the reader picture to himself a star-fish borne upon the summit of a
flexible stem firmly rooted in the soil, and he has a general idea of
the zoophytes which compose the order of the Crinoïdea. Naturalists of
the seventeenth century bestowed the name of _stone lilies_ on these
curious products. This rather poetical name proves that the conformation
of these creatures had at an early period attracted observation,
presenting the naturalist with the most curious of his lessons. The
encrinites raise, as from the dead, a whole world buried in the abyss of
the past. At the present time only two genera of these zoophytes exist,
whilst in the early ages of the world the ocean must have swarmed with
them. Encrinites abounded in the seas during the transition and
secondary epoch. It was one of the most numerous of the animal tribes
which inhabited the salt waters of the ancient world. In traversing some
parts of France, we tread under our feet myriads of these beings, whose
calcareous remains form vast beds of rock. The encrinites gradually
disappeared from the ancient seas; their species were diminished as the
globe became older or modified in its conditions, so that at the present
time only a few types remain in our seas--such as the _Comatula_ of the
Mediterranean; _Pentacrinus_, the Medusa's-head of the Antilles; and the
European _Pentacrinus_--all of them very rare, and probably destined
soon to disappear, carrying with them the last reminiscence of the
zoological races of the ancient world: and here lies the real interest
which the Crinoïdea presents to the thinking man. The encrinites most
common in the fossil state are _Pentacrinus fasciculosus_, belonging to
the lias; _Apiocrinus rotundus_, which is found in the oolite or
jurassic rocks; and _Encrinus liliformis_, which appertains to the
Triassic period. These three fixed zoophytes seem to have existed in
great numbers during an early age of the world--namely, the Silurian
period. They attained their maximum of development during the Devonian
age, after which they begin to decrease. According to M. D'Orbigny,
there are thirty-nine genera found in the palæozoic rocks, two in the
triassic, seven in the jurassic, five in the cretaceous, and only one in
the tertiary strata. Of all these genera only one, namely,
_Pentacrinus_, is found in the modern epoch to represent the varied
forms of these the first inhabitants of the seas.

The free Crinoïdæ, that is, those not rooted to the soil by a stem, of
which the _Comatula_ may be considered the type, only appeared at a
later period. They are absent in the palæozoic and triassic rocks, but
appear to have attained their maximum of development in the jurassic
period.

The numerous fossilized remains of these curious creations, which abound
in different rocks, attracted the attention of learned men at an early
period. The encrinites were among the earliest objects of scientific
description. As early as the sixteenth century, the celebrated
mineralogist, George Agricola, mentions them under the names of
_Entrochites_, _Trochites_, and _Astroïtes_. At the same time, and
since that epoch, the Crinoïdæ, which we know by the name of
stone-lilies, and which characterises the _Muschelkalk_ rocks, have been
known under the name of Encrinus, from εν, stone, and κρίνον, a
lily.

[Illustration: Fig. 107. Pentacrinus caput Medusæ (Müller).]

During the eighteenth century the works upon the Crinoïdæ were very
numerous, though not very correct. They sometimes reported these organic
remains to be vegetable; sometimes they were beings allied to the
star-fishes; at others they were the vertebral column of fishes. Towards
the year 1761, however, Guettard, one of the most learned naturalists of
his time, understood the real nature of these productions. He had
occasion to examine a recent Encrinus sent from Martinique under the
name of _Sea-Palm_, which was in reality _Pentacrinus caput Medusæ_. The
comparison of the living individual with the fossil fragment described
by his predecessors, and of which he had specimens in his collections,
enabled him to ascertain the real origin of the fossil Encrinoidæ. The
beautiful fragment which still exists in the Museum of Natural History
at Paris was long considered unique, but it is now known that ten others
exist in different museums. Since that date the Crinoïdæ have been
examined and described by observers such as Miller, Forbes, D'Orbigny,
and Pictet, and very elaborately by Major Austin.

[Illustration: Fig. 108. Pentacrinus Europæus (Thompson).]

"The species of fixed Crinoïdæ actually living are _Pentacrinus caput_
_Medusæ_ (Fig. 107), and _Pentacrinus Europæus_ (Fig. 108). These
curious zoophytes resemble a flower borne upon a stem, which terminates
in an organ called the calyx, but which is, properly speaking, the head
of the animal. Arms, more or less branching, spring from this calyx,
their ramifications, so formed, consisting of many pieces articulated to
each other. The calyx is supported by a stem, varying in height, formed
of pieces secreted by the living tissues which surround them. The
articulations of this stem are usually very numerous, cylindrical, and
present a series of rays striated upon their articulated faces. In
_Pentacrinus_ they are prismatic and pentagonal; that is, they present
five projecting angles, and on their articulated face a star with five
branches, or, better still, a rose with five petals. At the base of the
stem of this animal-plant, in many of the Crinoïdæ, we find a sort of
spreading root, which is implanted in the rocks, and is capable of
growing by itself, of nourishing the stem, and of producing new ones.

The root and stem of the fixed encrinites seem to indicate that the
animal can only live with the head erect. Their normal condition is thus
quite different from that of any other of the Echinoderms, almost all of
which keep their mouths invariably directed downwards.

The Medusæ heads are chiefly found on rocky beds, or in the midst of
banks of corals, at great depths. There, firmly fixed by their roots,
their long stems raise themselves vertically; then, with expanded calyx
and long-spreading arms, they wait for the prey which passes within
their reach in order to seize it.

The _Pentacrinus caput Medusæ_ have, as we have said, been fished up
from great depths in the Antilles. Its very small calyx is borne upon a
stem of from eighteen to twenty inches in height, terminating in long
movable arms, the internal surface of which bears its tentacles in a
groove. In the middle of the arms is a mouth, and at the side the
orifice for the expulsion of the digested residuum.

In the Medusæ head and European Pentacrine (_P. Europæus_, Fig. 108),
the presence of a digestive apparatus has been distinctly traced. It is
a sort of irregular sac, with a central mouth on the upper surface, and
another orifice situated at a little distance from the mouth, and
evidently intended as an outlet for the products of digestion. The arms
of these creatures, which are spreading or folded up according to their
wants, are provided with fleshy tentacula, which, serving at once as
organs of absorption and as vibratile cilia, are at the same time organs
of respiration. Such are these curious beings: they occupy a sort of
middle or transition state between animals permanently fixed to some
spot and those capable of motion, representing in our own times the last
remains of extinct generations. Every type of the Crinoïdæ furnished
with arms presents incontestable evidence of their mode of reproduction
or redintegration--that is, of the power of restoring those parts of the
body broken or destroyed by accident; but as we have already drawn the
attention of the reader to this strange faculty of renewing organs
which many of the zoophytes possess, we will not here enlarge further
upon the subject.

       *       *       *       *       *

The Crinoïdæ are not all like the two species which have been described.
There is an entire family of animals belonging to this class, namely,
the _Comatula_, which are fixed in their early days, but separate
themselves from the rooted stem in their adult age, and, throwing off
the bonds imposed on their youth, live side by side with the asterias,
with whose company they seem much pleased. The encrinites and the
star-fishes thus live in company, and that at prodigious depths, and
under a body of water which no light can reach. Imagine the existence of
animals which pass their lives in such eternal funereal darkness. The
family of Comatula are found in the seas of both hemispheres. Their
bodies are flat--a large calcareous plate formed like a cuirass upon
their backs--presenting, besides, cirri composed of numerous curling
articulations, the last of which terminates in a hook. The ventral
surface presents two orifices: the one in the centre corresponding to a
mouth, the other evidently intended for the discharge of the products of
digestion. This animal is provided with five arms, which diverge
directly from the centre plate or cuirass. The branches of these arms
have _ambulacral grooves_, comprehending a double row of fleshy
tentacles, in the centre of which is the ambulacral groove, properly so
called, clothed with vibratile cilia over their whole surface. These
cilia or hairs guide the current which drives the various substances on
which it feeds, such as the organic corpuscles of sea-weeds, and
microscopic animalcules floating in the sea, towards its mouth. They are
also powerful aids to respiration.

The movements of these curious creatures are very slow, their only
object being to catch the bodies of animals and marine plants, or, by
extending or contracting their arms, to feel their way through the water
to some new locality. Sometimes, also, in order to change their
feeding-ground, the Comatula abandon the submarine forests, herbage, and
sea-wracks, and float through the water, moving their arms with
considerable rapidity in search of a new station.

The Mediterranean Comatula (Fig. 109) is largely diffused on the
European shores of the Mediterranean. Its spreading arms extend to three
or four inches; its colour purple, shaded, and spotted with white upon
the ventral surface.

[Illustration: Fig. 109. Comatula Mediterranea (Lamarck), natural size.]

Were a traveller to tell us that he had seen animals drop their eggs
upon forests of stone; that these eggs, after executing their
progressive evolutions, finally become individuals in all respects like
their parents, which attach themselves to the soil by a root like any
flower of the fields, or to the mother-stem like the branch of a tree,
until in due course they attained the adult state, when the flexible
band which holds them fixed either to the soil or parent-stem breaks,
and the animal, now free, launches itself into the liquid medium, and
goes to live a proper and independent existence;--in listening to a
recital so opposed in appearance to the ordinary laws of Nature, we
should be inclined to tax the narrator of such incredible facts with
error or folly. Nevertheless all these facts are now perfectly
established. The being which presents these marvels has nothing of the
fabulous about it. It is the _Comatula Mediterranea_; it lives at the
bottom of the sea, the surface of which is incessantly tracked by our
vessels.


OPHIURADÆ.

The Ophiuras are thus named from two Greek words (ὅϕις, a serpent, and
οὑρὰ, a tail), from their fancied resemblance to the tail of a
serpent. These zoophytes are met with in almost every sea, but chiefly
in those of temperate regions; they are very common on every shore,
and have been remarked by fishermen from the earliest times on account
of their singular form, the disposition of their arms, which resemble
the tail of a lizard, and by the singularity of their movements. The
general characteristics of this remarkable group of Echinodermata, as
described by Dujardin and Hupé, are as follows. They are radiary marine
animals creeping at the bottom of the sea, or upon marine plants. In
form they present a sort of coriaceous disk, which is either bare or
covered with scales, which contains all the viscera, and five very
flexible simple or branching arms, each sustained by a series of
vertebral internal pieces, naked or covered with granules, scales, or
bristles. Certain fleshy tentacula thrown out laterally are organs of
respiration. The mouth is situated in the middle of the lower surface
of the disk, and opens directly into a stomach in the shape of a sac;
it is circumscribed by five re-entering angles corresponding with the
intervals of the arms, having a series of calcareous pieces, which
perform the function of jaw-bones. This mouth is prolonged by five
longitudinal clefts, garnished with papillæ or calcareous pieces, which
correspond to one of the arms. A series of calcareous pieces in the
shape of vertebræ spring from the extremity of each of these clefts,
which occupy all the interior of the arms, having a furrow in the
middle of the ventral surface for the reception of a nursing vessel;
and laterally between their expansions are certain cavities, from
whence issue certain fleshy retractile tentacula; the visceral cavity
opens by one or two clefts on the ventral surface of each side of the
base of the arms.

The Ophiuradæ move themselves by briskly contracting their arms so as to
produce a succession of undulations analogous to those by which a
serpent creeps along. Some of these zoophytes are rather active; but
others attach themselves by their arms to the branches of certain other
polyps, like the Gorgons, and remain immovable for a considerable time,
waiting their prey somewhat like a spider in the midst of his web.

The family of Ophiuradæ is divided into two great sections: that of the
Ophiura, which comprehends several genera, amongst others that which
gives its name to the family, and that of the Euryalina or Asterophytes.

[Illustration: Fig. 110. Ophiocoma Russei (Lutken), natural size.]

The family of Ophiuradæ constitute a group distinguished by their five
simple, articulated, very mobile, and non-ramified arms, which are
attached to a small disk or shield plate, with flexible thread-like
cirri between the rays. _Ophiura natta_ is very common, and has been
known from very early times in European seas. It is of a greenish
colour, with transverse bands, which become more obscure upon the arms
as the distance from the disk increases. This disk is from six to
seven-eighths of an inch in size, the upper part covered with unequal
plates, in shape like tiles; the arms are four times the length of the
diameter of the disk, very slender and tapering. The zoophyte to which
Lamarck gave the name of _Ophiura fragile_ has now its place among the
Ophisthrix, the specific name, indicating a particularity of structure
in all these small creatures derived from their fragile formation. In
short, these beings have so little consistency that they crumble, as it
were, under the touch, and become reduced to pulp under the slightest
pressure. In Fig. 110 we give the representation of an Ophiura of the
natural size, which Lutken has since called _Ophiocoma Russei_. This
Echinoderm, which lives in the seas of the Antilles, is furnished with
five very flexible rays, which are armed with from three to four rows of
spines, those on the upper part of the body being very hard ones; the
body and arms of this creature are of reddish brown, streaked with a
great number of little white lines.

[Illustration: Fig. 111. Asterophyton verrucosum (Lamarck).]

The principal type of the Euryalina is the curious and complex
_Asterophyton verrucosum_ of Lamarck. They include animals remarkable
for the extremely complicated development of their arms--the very
multiplied ramifications of these, towards the extremities, being
divided into many thousand very slender appendages, the principal use of
which is doubtless locomotion, but at the same time they constitute a
series of living thread-like fillets which seem intended to seize and
close upon the animals which serve as prey to this little flesh-eater.
The _Asterophyton verrucosum_, which is represented in Fig. 111, is
yellowish; its disk about four inches, its arms sixteen to eighteen. It
inhabits the Indian Ocean. Another species, _Euryala arborescens_, is
met with on the coasts of Sicily and other parts of the Mediterranean.
Nothing can be more elegant than these animated disks, which resemble
nothing so much as a delicate piece of lace--a piece of living lace
moving in delicate festoons in the bosom of the ocean.


ECHINIDÆ.

The singular shape of the Echinidæ, or Sea-urchins, and the spiny
prolongations with which their bodies are covered, has in all ages
attracted the attention of naturalists. Aristotle applied to them the
name ἐχῖνοϛ, which signifies urchin. When, however, one sees the
body of one of these animals thrown on the sea shore, it is difficult,
at first, to find a reason for this designation. The body of the
sea-urchin is furnished with a species of spine. It is a sort of shell,
nearly spherical, empty in the interior, its surface presenting reliefs
admirable for their regularity--an egg-shell sculptured by Divine
hands. In order to see the urchin with its spines, it is necessary to
seize it in the water at the bottom of the sea, where it rolls and
moves its little prickly mass; it is then only that the real urchin,
the prickly sea-urchin, is to be seen, bristling with prickles, and
strongly resembling, to compare the physical with the mental, those
amiable mortals whose character is so well depicted in the saying,
"Whom they rub they prick."

In his book on "The Sea," Michelet puts the following conversation into
the mouth of a sea-urchin:

"I am born without ambition," says the modest Echinoderm. "I ask for
none of the brilliant gifts possessed by those gentlemen the molluscs. I
would neither make mother-of-pearl nor pearls; I have no wish for
brilliant colours, a luxury which would point me out; still less do I
desire the grace of your giddy Medusas, the waving charm of whose
flaming locks attracts observation and exposes one to shipwreck. Oh
mother! I wish for one thing only: _to be_--to be without these exterior
and compromising appendages; to be thick-set, strong, and round, for
that is the shape in which I should be the least exposed; in short, to
be a centralized being. I have very little instinct for travel. To roll
sometimes from the surface to the bottom of the sea is enough of travel
for me. Glued firmly to my rock, I could there solve the problem, the
solution of which your future favourite, man, seeks for in vain--that of
safety. To strictly exclude enemies and admit all friends, especially
water, air, and light, would, I know, cost me some labour and constant
effort. Covered with movable spines, enemies will avoid me. Now,
bristling like a bear, they call me an urchin."

[Illustration: Fig. 112. Echinus mamillatus (Lamarck), natural size.]

Let us now look a little more closely at the general structure of the
sea-urchins--in zoological language, Echinidæ.

[Illustration: Fig. 113. Echinus mamillatus. Sea Urchin, without spines,
natural size.]

The body of the sea-urchin is globular in form, slightly egg-shaped, or
of a disk slightly swollen. It consists essentially of an exterior shell
or solid carapace, clothed in a slight membrane furnished with vibratile
cilia. This carapace is formed of an assemblage of contiguous polygonal
plates, adhering together by their edges. Their arrangement is such that
the test or shell may be divided into vertical zones, each springing
from a central point on the summit terminating at a point of the
spheroid diametrically opposite--namely, the circumference of the buccal
orifice. These vertical zones are of two kinds, some larger and others
straighter, each zone consisting of a double row of plates, the first
charged with movable spines, the second pierced with holes disposed in
regular longitudinal series, from which emerge certain fleshy tentacula,
which, as we shall see presently, serve as feet to the animal. When
armed with these bristling spines, the sea-urchins resemble the
hedgehogs; but when the spines are down, they look very much like a
melon or an egg, to which their shape and calcareous nature have
sometimes led to their being compared by the vulgar as well as by the
learned. We shall give a tolerably exact idea of the two different
aspects which the carapace of the urchin presents when the spines are
erect and lowered, by reference to Fig. 112 (_Echinus mamillatus_),
which represents the animal bristling with spines, and Fig. 113, in
which the same species is represented after death, when deprived of
these weapons of defence: and how complicated these defences must be! It
has been calculated that more than ten thousand pieces, each admirably
arranged and united, enter into the composition of the shell of the
sea-urchin, to which no other can be compared. To abbreviate slightly
Gosse's description of that wonderful piece of mechanism, the
sea-urchin: "A globular hollow box has to be made, of some three inches
in diameter, the walls of which shall be scarcely thicker than a wafer,
formed of unyielding limestone, yet fitted to hold the soft tender parts
of an animal which quite fills the cavity at all ages. But in infancy
the animal is not so big as a pea, and it has to attain its adult
dimensions. The box is never to be cast off or renewed; the same box
must hold the infant and veteran urchin. The limestone can only increase
in size by being deposited. Now the vascular tissues are within, and the
particles they deposit must be on the interior walls. To thicken the
walls from within leaves less room in the cavity; but what is wanted is
_more_ room, ever more and more. The growing animal feels its tissues
swelling day by day, by the assimilation of food. Its cry is, 'Give me
space! a larger house, or I die!' How is this problem solved? Ah! there
is no difficulty. The inexhaustible wisdom of the Creator has a
beautiful contrivance for the emergency. The box is not made in one
piece, nor in ten, nor a hundred. Six hundred distinct pieces go to make
up the hollow case; all accurately fitted together, so that the perfect
symmetry of the outline remains unbroken; and yet, thin as their
substance is, they retain their relative positions with unchanging
exactness, and the slight brittle box retains all requisite strength and
firmness, for each of these pieces is enveloped by a layer of living
flesh; a vascular tissue passes up between the joints, where one meets
another, and spreads itself over the whole exterior surface."

This being so, the glands of the investing tissue secrete lime from the
sea water, and deposit it after a determinate and orderly pattern on
every part of the surface. Thus the inner face, the outer face, and each
side and angle of polyhedron, grow together, and the form characteristic
of the individual is maintained with immutable mathematical precision.
The dimensions and shape of these prickles are very variable. In certain
Echinidæ they are three or four times the diameter of the body. In the
urchin, properly so called, they are only three-fourths or four-fifths
that diameter. They sometimes resemble short bristles. These defensive
weapons have tubercles for supports, which are arranged on the surface
of the animal with perfect regularity. At the base they present a small
head separated by compression. This head is hollow on its lower face,
presenting a cavity adapted to a tubercle of the shell. Each of the
prickles, notwithstanding its extreme minuteness, is put in action by a
muscular apparatus.

[Illustration: Fig. 114. Echinus esculentus (Lamarck), natural size.]

In the prickles, or spines and tentacula (ambulacra, _feet suckers_), we
see the external organs of the Echinodermata. The former are instruments
of defence and progression; the latter, strange as it may appear, serve
them to walk with. When it is considered that each of these prickles is
put in motion by several muscles, it is impossible to repress our
wonder and surprise at the prodigious number of organs brought into
action in the sea-urchin. More than twelve hundred prickles have been
counted upon the shell of _Echinus esculentus_, a representation of
which is given in Fig. 114. If we add to this first supply of spines
other smaller and in some sort accessary spines, we shall arrive at a
total of three thousand prickles. Each sea urchin thus bears as many
weapons as ten squadrons of lancers. When it is considered, further,
that in each sucker or ambulacra there exist not less than a hundred
tubes, each having an orifice, you will have a total of four thousand
visible appendages upon the body of an animal of very small dimensions.
If it is considered, finally, that no shell exists more admirably
symmetrical, elegant, or more highly ornamental than the carapace of the
urchin, it will readily be admitted that Nature has been most prodigal
in her gifts to one of the humblest beings in creation--a creature which
passes its existence in crawling in obscurity at the bottom of the sea.
What elegance of form, eternally hidden from the eyes of man, sleeps
under the heavy mass of water; and yet man imagines that everything in
Nature has been created for his use and for his glory.

M. Hupé records a somewhat curious observation in connection with the
spines, which serve as a means of defence to the Echinodermata. He found
a small mollusc, of the genus _Stelifera_, which had sought shelter in
_Leixidaris imperialis_, an urchin, native of Australia; in a word, the
interior of one of these prickles had been hollowed and enlarged so as
to serve as a retreat for this improvised guest.

What unexpected facts does the study of animals present! Nature has
bestowed a protecting armour upon one little being; another still
smaller animal discovers this, and places itself for shelter under the
protection of these levelled bayonets! Numerous anecdotes are told of
them. Thus: a man ignorantly put into his mouth one of these creatures,
with all its prickles, and, being detected, thought himself, in his
pride, compelled to swallow it because he was being looked at;
immediately his mouth was full of blood. The next day he was in such a
state of suffering that he could neither eat nor drink, and for a long
time his life could only be preserved by nourishing injections of soup,
cream, and rice.

Now let us see by what organic mechanism the urchin contrives to
transport itself and walk. The tentacula, or suckers, are hollow
internally, and, as we have said, are provided with small muscles. By
the influx of liquid which they inclose they become inflated throughout
all their prickles, in such a manner that they can attach themselves to
any solid body, at the will of the animal, by means of their terminal
suckers. Frédol, in "Le Monde de les Mers," thus explains the urchin's
mode of progression. "Let us imagine," he says, "one of these creatures
to be at rest; all its spines are immovable, and all its filaments
repose within the shell; some of these involuntarily escape; they extend
themselves and feel the ground all round them: others follow, but the
animal is firmly fixed. If it wishes for change of place, the anterior
filaments contract themselves, whilst the hinder ones loosen their hold,
and the shell is carried forward. The sea-urchin can thus advance with
ease, and even rapidity. During his progression the suckers are only
slightly aided by the spines. It can travel either on the back or
stomach; whatever their posture, they have always a certain number of
prickles, which carry them, and suckers, with which they attach
themselves. In certain circumstances the animal walks by turning upon
itself, like a wheel in motion."

Nothing is more curious than to see a sea-urchin walk upon smooth sand.
But for the colour, it might be mistaken for a chestnut with its
bristling envelopes, the spines serving as feet to put the little round
prickly mass in motion. They have even been observed to form themselves
into a ball, and roll along like a globular fagot of prickles.

[Illustration: Fig. 115. Buccal armature of Echinus lividus.]

One of the most singular organs of the sea-urchin is its mouth. It is
monstrous. Placed underneath the body it occupies the centre of a soft
space invested with a thick resisting membrane: it opens and shuts
incessantly, showing five sharp teeth (Fig. 115) projecting from the
surface, the edges meeting at a point, as represented here, supported
and protected by a very complicated framework, which has received the
name of Aristotle's Lantern (Fig. 116). Fig. 115 represents _Echinus
lividus_ in its normal state; the other shows the masticatory organs,
that is to say, Aristotle's Lantern. To give the reader a more complete
idea of the buccal organ in the sea-urchin, let him glance at one from
the southern seas, _Clypeaster rosaceus_, represented in Fig. 117, an
outline of the entire animal, the buccal apparatus being placed under
the shell, which has been broken in Fig. 116, so as to lay this organ
bare.

[Illustration: Fig. 116. Masticating apparatus of Echinus lividus.]

The shape of the _Clypeaster rosaceus_ is oval, straighter in front, and
thick and rounded at the edges. It is more common and more largely
distributed than any other living species, and it is supplied with four
or six ambulacra, or feet.

I never could understand why the dental framework of the sea-urchin has
been called Aristotle's Lantern, for this formidable apparatus resembles
the front view of a battery of cannon more than a lantern. It consists
of a series of pieces designated by the names of compass, scythe,
pyramid, and plumula, which it would serve no useful purpose to
describe.

[Illustration: Fig. 117. Clypeaster rosaceus (Lamarck).]

We have said that the mouth of the urchin is monstrous in proportion to
its size, and the teeth of proportionate dimensions. As these project
from a very formidable mouth, one can easily be assured of the sharpness
of their extremities by intruding his fingers on them. In fact, it is
necessary that these organs should be singularly powerful, because, as
we shall see farther on, the sea-urchin makes incisions in the solid
rock with them, and hollows out shelter for himself. The strong and
sharp teeth grow at the base in proportion as they are used at the
points, as is the case with some of the rodent mammalia. By this means
they are always sharp and in good condition. Five groups of powerful
muscles are used to work these terrible grinders.

To this formidable mouth is attached an œsophagus or gullet, and an
intestine which extends along the interior walls of the carapace,
describing the circumference of its principal contour.

The regimen of the Echinidæ is still imperfectly known; nevertheless,
from the presence of shells, fragments of corals, crustaceans, and even
other Echinodermata in their intestinal tube, it is to be inferred that
a certain number of them at least are carnassiers, or flesh-eaters,
while others are supposed on the same evidence to be vegetarians. The
organs of respiration of the Echinidæ appear to be certain flattened
vesicles in the form of very delicate laminæ, which adhere to the
internal surface of the walls of the body, and float freely in the
liquid with which the visceral cavity is filled. These organs, known as
the internal _branchiæ_, are in communication with the central canal and
ambulacral tubes. The heart is spindle-shaped, tapering above, swelling
below. There are two distinct vascular systems, one intestinal, the
other cutaneous.

[Illustration: Fig. 118. Skeleton and Masticating Apparatus.]

Their nervous system consists of a ring, which surrounds the gullet, and
is placed at a short distance from the mouth. In this ring the nervous
trunks have their origin. In relation to the senses, that of touch is
highly developed. Certain branching tentacula, which surround the mouth,
fashioned like nippers, and the ambulacral tentacles, are its principal
organs. They appear to be altogether destitute of organs of sight. It
has sometimes been argued that four or five red points at the summit of
the dorsal face are eyes; but this opinion has not been maintained, nor
has any crystalline lens been found in these spots to justify it.
Captain de Condé states that he examined a sea-urchin with long spears
in a pool of water, which he tried to catch, when he saw it direct its
flight towards his hand, all its defences being erect. Surprised at this
manœuvre, he tried to seize it from another quarter; its spines were
instantly directed to the other side. "I have thought from that time
that the urchin saw me, and prepared to resist my attack. In order,
however, to satisfy myself whether or not the movement in the water
caused by my approach might have produced the effect described, I
repeated the experiment with greater caution. But the creature always
directed its spines in the direction of the object which threatened it,
whether it was in the water or out of it." He satisfied himself that
these animals certainly could see, and that their spines served them as
a means of defence.

These wonderful spines, this calcareous envelope, this armour so
marvellously studded, with which nature has so bountifully provided the
Echinidæ, appear to have been insufficient, inasmuch as these very
spines, in order to secure the safety of the animal, are gifted with the
power of hollowing a dwelling for themselves out of solid rocks of the
hardest material, such as granite and sandstone. They fix themselves to
its surface by means of their tentacles; they make an incision by means
of their strong teeth, removing the débris with their spines as fast as
it is produced. When the hole is large enough, they entrench themselves
in it, with their spines and their threatening pikes levelled to protect
them from all external assaults. To M. Caillaud, the conservator of the
museum of Nantes, we are indebted for an excellent account of the manner
in which this buccal apparatus is made to operate. "The Lantern of
Aristotle," says this author, "forms the mandibullary apparatus; the
teeth are five in number, and they may as well receive the denomination
of a series of saws and picks as of teeth, for they are surprisingly
adapted to the excavation of holes in the hardest rock. These five picks
are about the eighth of an inch long, and they serve the sea-urchin at
once as masticators and excavating implements. In opening the jaws,
these five teeth strike the stone forcibly rather than scrape it." This
property of hollowing their dwelling out of the solid rock appears,
however, to belong to only a small number of the Echinidæ; most of them
are content to hide themselves under the stones, while the species
having the spines slender and the shell very thin bury themselves in the
sand, with which they cover themselves entirely, leaving only a small
hole to breathe through. The _Spatangus_, which is furnished with short
thick spines on the under part of its body, which spread out at the
extremity like the channel of a spoon, proceeds with its mining
operations as follows, according to Mr. Jonathan Franklin. "Figure to
yourself, reader, the animal on the sea-shore. He commences his
operations by turning the lower spines in such a manner as to form a
hollow on the sand bank, in which he sinks by his own weight; but as he
sinks, a great number of the spines are brought into action, throwing
up the sand with increased activity, while the sand thrown up, returning
again, soon covers the body of the worker, and he has soon buried
himself beneath the surface. In this situation the long hair-like spines
situated upon the back begin to play their part; they prevent the sand
from entirely covering the animal by forming a little round hole,
through which water is introduced to the mouth and respiratory organs."
The hiding-place of the sea-urchin is, however, easily detected in the
sand by the hole thus arranged for the respiration of the animal, and
the fishermen think they can predict storms according to the depth of
the hole.

The Echinidæ are reproduced by eggs, which are red and nearly
microscopic. As it issues from the egg the larva has the appearance of a
very minute fish. It is not at once converted into the perfect animal,
but undergoes a certain metamorphosis analogous to that of the
caterpillar into the butterfly. But, as we have already stated in
treating of the Asteriæ, it produces, at a certain stage, by some sort
of internal process of generation, a sea-urchin, which, being at first
only an organ of the larva, begins to live an independent life when the
nursing larva has destroyed itself. The manner in which the urchin
unfolds itself at the expense of the larva is quite analogous to that
which the asterias present: it is another case of alternate generation,
of which our space does not permit us to give even a general outline.

Sea-urchins are found in every sea; they dwell in sandy bottoms, and
sometimes upon rocky ground. They are caught with wooden pincers when in
shallow water; when found at the water's edge, they may be taken by a
gloved hand.

The urchin, like the crab, which it also resembles in taste, becomes red
when boiled; only certain species are comestible, however. In Corsica
and Algeria the Melon-shaped Urchin (_Echinus melo_) is much esteemed.
In Naples and in the French ports of the Channel the _Echinus lividus_
is eaten. In Provence the Common Sea-urchin (_Echinus esculentus_ and
_Echinus granulosus_) are the favourites.

Sea-urchins are eaten raw like oysters. They are cut in four parts, and
the flesh taken out with a spoon; they are sometimes, but more rarely,
dressed by boiling, and eaten from the shell like an egg, using long
sippets of bread: hence the name of sea-eggs, which they bear in many
countries.

[Illustration: Plate IX.--Sea Urchins lodged in the rocks they have
excavated.]

Sea-eggs were a choice dish upon the tables of the Greeks and Romans;
they were then served up with vinegar or hydromel, with the addition of
mint or parsley. When Lentulus feasted the priest of Mars--the Flamen
Martialis--this formed the first dish at supper. Sea-eggs also appeared
at the marriage feast of the goddess Hebe. "Afterwards," says the poet,
"came crabs and sea-urchins, which do not swim in the sea, but content
themselves by travelling on the sandy shore." For my own part, I have
only once partaken of sea-urchin, and it appeared to me to be food fit
for the gods; but perhaps the circumstances sufficiently explain this
dash of culinary enthusiasm. The Reserve Restaurant at Marseilles has
not always been the vast stone edifice we now behold, backed
majestically by the mountain, and fronting the sea on the promenade of
the Corniche du Prado. In 1845 it rose quite at the entrance of the
port, a small glass cage, suspended as it were by a magic thread between
the heavens and the sea. From this aërial dwelling, overhanging with
unheard-of audacity the waters which surrounded it on all sides, we
gazed on the most wonderful prospect in the world, and reposed ourselves
while enjoying this intoxicating scene, during which the ships were
continually entering the port, passing under our very feet. It was in
this enchanted palace that sea-urchins were served up, supported by the
traditional bouillabaise.

As I have said, it appeared to me delicious. Was it the Provençal dish,
the savoury bouillabaise, which contributed to my appreciation of the
humble sea-urchin of the Mediterranean? Was not the marvellous view
which I enjoyed from the heights of my empyreum of glass the indirect
cause of it? This is a tender and charming problem which I love to leave
floating in the clouds, half evanescent, of my youthful recollections.


HOLOTHURIA.

The ignorant, like you and I, call the Holothuria the Cornechou, or
Sea-cucumber, and perhaps, for two reasons, they are not far wrong. The
term sea-cucumber expresses with wonderful exactness the shape of the
animal, and its habitation, the sea; and, again, it would puzzle the
most learned to explain the word _Holothuria_. The body of this strange
creature presents the form of an elongated and worm-like cylinder; its
dimensions are so variable that, while some species are only an inch or
two in length, others attain thirty and even forty. In general, the skin
of the Holothuria is thick and leathery; it includes muscles, and is
armed occasionally with small projecting hooks or fangs, which enable
the creature to hang for a few seconds on to foreign bodies. From this
coriaceous envelope issue tentacular feet analogous to those described
in the sea-urchin and sea-star.

When we open a Holothuria we find nearly the whole internal cavity
occupied with little white tubes. We know that the fabulous cucumber
spoken of in the "Arabian Nights" was stuffed with pearls by the
talking-bird. With our poor animal this, alas! is not so. These are no
pearls, but simple prosaical tubes containing the ova. The mouth opens
at the extremity of the body; it forms a sort of funnel, and is
surrounded, as by a glory, with an elegant circle of tentacula. In the
living animal, when it feels itself in security, these tentacles expand
themselves like the corolla of a flower. When the fisherman seizes a
Holothuria in the water this crown of tentacles ceases to appear, for
the animal has the power of withdrawing it quite suddenly, and now it
resembles nothing so much as a common leech. If, however, it is
preserved in fresh sea-water and left in peace--if we treat it, in
short, with the regard due to its elegant crown of tentacula--this
elegant ornament will be expanded in all its glory. Immediately below
the mouth is a muscular pharynx, which is contained in a long intestine,
with many convolutions, which terminate in the posterior part of the
body in an orifice whence is thrown from time to time a little jet of
water. The terminal portion of the intestinal canal in these animals is
enlarged, introducing us to a system of numerous tubes which branch off
into the visceral cavity, receiving the water from without while
breathing by its posterior extremity; the animal can at will fill this
reservoir or eject the water, and it is by these alternate movements of
aspiration and its reverse that it renews the oxygen necessary for
respiration. The circulation appears to form a complete circle, there
being no heart or central agent; but a ring round the gullet, from which
issue five principal nervous chords, represents the nervous system.

The Holothurias are of separate sexes, and they differ from the
sea-urchins and asterias in this: that their larvæ are converted bodily
into a young Holothuria without losing their organs. The bodies of
certain species are lubricated by an acrid and corrosive liquid: thus
_H. oceania_, described by Lesson, which is about forty inches in
length, secretes at the surface of its body an irritating fluid, which
produces an intolerable itching in the finger which touches it. Nor can
the inhabitants of the South Sea Islands look at it without loathing.
Fig. 119 represents _H. lutea_, or the _Stychopus luteus_ of Brandt, who
describes as its distinctive character three rows of tentacular feet on
the ventral surface.

[Illustration: Fig. 119. Holothuria lutea (Quoy and Gaimard).]

We have spoken of the strange suicidal tendency of the sea-stars: the
Holothuria exhibits the same phenomena, but, having no brittle envelope
like the asterias, it cannot break itself into bits in the presence of
its disconcerted enemy; but kills itself in this manner: having some
cause of grief and trouble--such, for instance, as the attack of an
enemy or the pursuit of some fisherman--by a sudden and unexpected
movement it ejects its teeth, its stomach, its digestive apparatus, and
reduces itself to a simple empty membranous sac, with an unfurnished
mouth; and, as a singular fact, this empty sac still shrinks and
contracts in the hand which grasps it. It must be admitted that this is
a strange mode of evading its enemies: the soldier rarely throws his
arms away in the moment of danger! But the Holothurias possess a
wonderful recuperative power also; and it is probably quite conscious,
when it thus empties itself to disappoint its pursuer, that it can
promptly replace the organs which it has voluntarily parted with.

Dr. Johnston relates that he had forgotten for some days to supply a
Holothuria with a change of water. The creature, in consequence, ejected
its tentacles, its buccal apparatus, digestive tubes, and a portion of
its ovaries. Still it was not dead, but was sensible to the least
movement, and lived to reproduce all its organs anew.

Not only do the Holothurias eject their organs and afterwards renew
them, but they divide themselves spontaneously into two portions. Their
two extremities are first enlarged; then their middle parts gradually
become straight, like a thread: finally, this thread breaks, and each
separate part of the animal becomes a perfect Holothuria. It has been
cut into two pieces, and each of these species becomes a new being.

[Illustration: Plate X.--Fishing for and curing the Holothuria in the
Indian Ocean.]

The habits of these animals are but little known. They inhabit the seas,
and are spread over every latitude. Their very limited movements consist
in a kind of reptation or crawling motion, produced by the undulations
of their bodies or by the contractions of their feet. Holothurias are
generally found in the act of creeping upon stones or on portions of
submarine rock, but always in sheltered places, for they appear to dread
the action of light. They sometimes find themselves caught by fishermen
in their nets. If held in the hand they contract, their bodies become
hard and rigid, and the sea water with which they are filled is ejected
with force. We need not add that fishermen reject with disdain the
Holothurias taken in their nets; the sea-cucumber has never been thought
worthy of a place on our tables. Truth is on this side, error on that,
is a maxim as true in morals as in cookery. The sea-cucumber, which
Europeans disdain, is a favourite dish among the Chinese. The fishery,
preparation of, and transport of these animals to market, plays an
important part in the commerce and industry of the East. One rather
large species, the _Holothuria tubulosa_, in which, by-the-bye, a
singular parasite fish (_Fierasfer fontanesii_) lives, is common in the
Mediterranean. This species is eatable, and much relished at Naples. In
the Ladrone Islands _Holothuria guamensis_ is preferred. But nowhere is
it esteemed of such importance as in the Malayan and Chinese seas. In
these countries, and on most of the shores of the Indian Ocean, the
_Holothuria edulis_, vulgarly called _Trepang_, is eaten with delight.
Thousands of junks are annually equipped for the Trepang fisheries. The
Malay fishermen carry to this fishery a degree of patience and dexterity
truly remarkable. Lying down in the fore part of their vessels, and
holding in their hands a long bamboo, terminating in a sharp hook, their
eyes, accustomed to this fishing, frequently discover the animal at a
distance of not less than thirty yards, as it creeps along the surface
of the submarine rocks or corals. The fisher darts his harpoon at this
distance, and seldom misses his prey. When the water is shallow, that is
to say, not more than four or five fathoms deep, divers are sent down to
obtain these culinary monsters, who seize them in their hands, and in
this manner can take five or six at a time. To prepare the fish and
preserve them for transport to the markets, the Malay and Chinese
fishermen boil them in water, and flatten them with stones. They are
then spread out on bamboo mats to dry; first in the sun, and then by
smoking them. Thus prepared, they are enclosed in sacks, and shipped to
the Chinese ports, where they are particularly esteemed. This fishery
takes place in the months of April and May.

In his voyage to the South Pole, Captain Dumont d'Urville, in traversing
the Chinese seas, had an opportunity of assisting at this fishery, which
he has described very graphically. We quote the passage in which the
French navigator relates what he witnessed at this curious scene. While
the ships were lying quietly at anchor, "we saw," he says, "entering the
bay, four Malay proas, bearing Dutch colours, which dropped their
anchors about a cable's length from Observatory Islet. The padrones or
captains of these vessels soon presented their salutations, and informed
me that they had started from Macassar at the end of October, with the
western monsoon, and that they came to fish for Holothuria (trepang)
along the coasts of New Holland, from Melville Island to the Gulf of
Carpentaria, where the east wind met them and assisted their return,
when they revisited all the points of the coast, anchoring in every bay
where they hoped to find fish. We were in the first days of April; the
east monsoon was definitively established; the Malay fishermen were
returning in their circuit, and, in passing, they came to exercise their
industry in Raffles' Bay. An hour after their arrival they were all at
work, and the laboratory for the preparation of their fish was
established within our view. The roadstead had no longer the aspect of a
vast solitude: wreaths of smoke crowned the summit of Observatory
Island, where, as if by enchantment, several large sheds had sprung up,
while numerous vessels, supplied with divers, were proceeding to fish
for Holothurias, which were passed immediately to the furnaces erected
for curing them. In the course of my voyage I have often remarked little
walls constructed of dry stones, consisting of several half-circles
joined one to the other. I had often, but vainly, tried to discover the
use of these little structures: I was now enlightened. The Malays
arrived. Their boats were scarcely anchored when several large boilers,
in the shape of a half-sphere, the diameter of which might be about
forty inches, were placed upon the stone walls of which I have spoken,
and now served as improvised furnaces. Near to them are sheds, composed
of four strong posts driven into the earth, supporting roofing covered
with hurdles, on which it is probably intended to dry the Holothurias.
During their sojourn in this bay, the fishermen, having fine weather,
made no use of these sheds, having probably only prepared them as a
precaution.

"A crowd of men actively employed in establishing their laboratories
gave an unaccustomed appearance to the bay, which could not fail to
attract the savage inhabitants of the main land. Very soon, indeed, we
could see them hastening from all sides, and nearly all reached the
little island, either by swimming or wading through the sheet of shallow
water which separates it from the main land. I only saw one pirogue,
made of the bark of a tree badly put together, which gave a passage to
three of these visitors. When night arrived, the Malays had finished all
their preparations; some of them remained to guard what they had left on
shore, all the others returned to their boats.

"In the interval, a boat from the Astrolabe being wanted to carry some
visitors from the island, I profited by the occasion to visit one of
the proas, accompanied by M. Roquemauel. We were received with much
politeness, and even cordiality, by the captain or padrone of the boats.
He showed us over his little ship. The keel appeared to us sufficiently
solid; even the lines did not want elegance; but great disorder seemed
to reign in the stowage department. From a kind of bridge, formed by
hurdles of bamboos and junk, we saw the cabin, which looked like a
poultry-house; bags of rice, packets, and boxes were huddled together.
Below was the store of water, of cured trepang, and the sailors' berths.
Each boat was furnished with two rudders, one at each end, which lifted
itself when the boat touched the bottom. The craft was furnished with
two masts, without shrouds, which could be lowered on to the bridge at
will by means of a hinge; they carry the ordinary sail; the anchors are
of wood, for iron is rarely used by the Malays; their cables are made of
ratan fibre; the crew of each bark consists of about thirty-seven, each
shore-boat having a crew of six men. At the moment of our visit they
were all occupied in fishing operations, some of them being anchored
very near to us. Seven or eight of their number, nearly naked, were
diving for trepang; the padrone alone was unoccupied. An ardent sun
darted his rays upon their heads without appearing to incommode them, an
exposure which no European could hold up under. It was near mid-day, and
the moment, as our Malay captain assured us, most favourable for the
fishing. In fact, we saw that each diver returned to the surface with at
least one animal, and sometimes two, in his hands. It appears that the
higher the sun is above the horizon, the more easily is the creature
distinguished at the bottom. The divers were so rapid in their
movements, that they scarcely touched the boat, into which they threw
the animals, before they dived again. When the boat was filled with
them, it proceeded to the shore, and its place was supplied by an empty
one. I followed one of these, to witness the process of curing which
they adopted.

"The Holothuria of Raffles' Bay is from five to six inches long and
about two in diameter; it is a gross fleshy mass, somewhat cylindrical
in form, but no external organ is visible. The mollusc glues itself to
the rocks at the bottom of the sea, and, as it can only move very
slowly, the Malay divers seize it readily. The greatest merit of a
fisherman is to have a practised eye, to distinguish the animal at the
bottom, and to dive directly to the spot where it lies. To preserve
them, the fishermen throw them, while still living, into a cauldron of
boiling sea water, where they are stirred about by means of a long pole,
which is supported upon another pole fixed in the earth, but having a
forked end, which acts as a lever. In this process the trepang gives up
all the water it contains, and is withdrawn at the end of two minutes. A
man armed with a large knife now extracts the entrails, and it is thrown
into a second cauldron, having only a small quantity of water, seasoned
with mimosa bark. The object of this second operation is to smoke the
animal in order to preserve it the better, for the bark is consumed in
the process. The trepang is now placed upon hurdles and dried in the
sun. When sufficiently dried, it is stowed away in the hold of the proa.

"It was about two o'clock in the afternoon when the divers ceased their
labours and came ashore. My tent was soon surrounded. I recognized the
captain of the proa among those who had previously visited me. He
approached and examined all the instruments used in the Observatory with
great attention, seeking to discover their use. I showed him a gun with
percussion cap, which astonished him greatly, especially when I pointed
out to him its great superiority over the flint-lock. He assured me that
these arms were still unknown in the Celebes, his country; but he failed
to convince me of that. He questioned me as to the places we had
visited, and where we were going. I endeavoured to sketch a map of New
Holland, New Zealand, and New Guinea upon a leaf. He then took my
pencil, and added to it the Indian Archipelago, the coasts of China and
Japan, and the Philippine Islands. Surprised in my turn, I asked him if
he had visited all these places. He replied in the negative; but added
that he knew their position perfectly, and could easily take his vessel
to any of them. Finally, the interview terminated by his asking for a
glass of arrack. I do not know if this intelligent Malay professed the
Mahometan religion, but I do know that he drank half a bottle of wine
and a quarter of a pint of arrack without being at all the worse for it.
He then offered me some prepared trepang, inviting me to taste it, which
I did; to me it appeared to resemble the lobster in taste. My men liked
it, and thankfully accepted the captain's offer; for my part, I felt an
utter repugnance even to taste it.

"According to the account I had from the Malay captain, the price of
trepang in the Chinese markets was fifteen rupees, about thirty
shillings the pekoul, or a hundred and twenty-five pounds. He
estimated his cargo to be worth about a hundred and twenty pounds. The
fishing had occupied him and his crew three months. From the earliest
times this commerce has belonged exclusively to the Malay fishermen, and
it will always be difficult for Europeans to compete with them. The
Malay vessels are equipped on the most economical principle, and the men
are wanting neither in sobriety, intelligence, or activity.

[Illustration: Plate XI.--Synapta Duvernæa. (Quatrefages.)]

"It was nearly four o'clock when the Malays finished their operations.
In less than half an hour they had embarked their cargo; the tents were
struck, and, together with the boilers, carried back to the boats, which
were already preparing to set sail. At eight o'clock in the evening they
hoisted sail and left the bay."

Some idea may be formed of the extent and importance of the Holothuria
fishing by the number of ships which it attracts in this part of the
East. Captain King assures us that two hundred vessels annually leave
Madagascar to fish for the _sea slug_, as it is sometimes called.
Captain Flinders, being on the coast of Australia, learnt that a fleet
of sixty vessels, having a hundred men on board, had left Madagascar two
months previously in the same pursuit.

Among the Holothurias, one particular genus, the _Synapta_, is
distinguished from others of the family by the absence of the ambulacral
feet, and by the fact of its uniting both sexes in one individual. This
remarkable Echinoderm, _Synapta duvernæa_, is represented in PL. XI. M.
Quatrefages, who discovered it in the Channel, gives the following
description of it in his great work, "Le Souvenirs d'un Naturaliste."
"Imagine," he says, "a cylinder of rose-coloured crystal, as much as
eighteen inches long and more than an inch in diameter, traversed in all
its length by five narrow ribbons of white silk, and its head surmounted
by a living flower, whose twelve tentacles of purest white fall behind
in a graceful curve. In the centre of these tissues, which rival in
their delicacy the most refined products of the loom, imagine an
intestine of the thinnest gauze gorged from one end to the other with
coarse grains of granite, the rugged points and sharp edge of which are
perfectly perceptible to the naked eye.

"But what most struck me at first in this animal was, that it seemed
literally to have no other nourishment than the coarse sand by which it
was surrounded. And then when, armed with scalpel and microscope, I
ascertained something of its organisation, what unheard-of marvels were
revealed! In this body, the walls of which scarcely reach the sixteenth
part of an inch in thickness, I could distinguish seven distinct layers
of tissue, with a skin, muscles, and membranes. Upon the petaloid
tentacles I could trace terminal suckers, which enabled the Synapta to
crawl up the side of a most highly polished vase. In short, this
creature, denuded to all appearance of every means of attack or defence,
showed itself to be protected by a species of mosaic, formed of small
calcareous shield-like defences, bristling with double hooks, the points
of which, dentated like the arrows of the Caribbeans, had taken hold of
my hands."

If one of these Synapta is preserved alive in sea-water for a short
time, and subjected to a forced fast, a very strange phenomenon will be
observed. The animal, being unable to feed itself, successively detaches
various parts of its own body, which it amputates spontaneously. A great
compression or ring is first formed, and then the separation of the
condemned part takes place quite suddenly. "It would appear," says M.
Quatrefages, "that the animal, feeling that it had not sufficient food
to support its whole body, was able successively to abridge its
dimensions, by suppressing the parts which it would be most difficult to
support, just as we should dismiss the most useless mouths from a
besieged city."

This singular mode of meeting a famine is employed by the Synapta up to
the last moment. After a few days, in fact, all that remains of the
animal is a round ball, surmounted by its tentacles. In order to
preserve life in the head, the animal has sacrificed all the other parts
of its body.

In order to find natural novelties--to find unforeseen subjects of study
and reflection, it is not necessary to run over the world or travel
great distances. It is only necessary to visit the banks of the nearest
river, or descend to the sea shore, and leave the sea to reveal a
fragment of the marvels which it conceals in its bosom.



MOLLUSCA.


The class Mollusca--pulpy animals--forms a grand division which man has
been pleased to make in the animal kingdom, and immediately below the
Vertebrata and above the Annulosa, which again stand above the
Coelenterata, which includes the polyps, sea-anemones, hydras, and
corals, which last are more highly organized than the Protozoa.

[Illustration: Fig. 120. P. C. Mollusca.]

The Mollusca may be divided into two groups, the Mollusca proper and the
Molluscoïda. The mollusc proper, as represented in Fig. 120, presents
the following parts, and is supposed to be bilaterally symmetrical, H,
is the hæmal parts, in which the heart is situated, commonly called the
dorsal part, although the word is used in a different sense in different
divisions of the animal kingdom. In the same manner the opposite region
(N) is not termed the ventral, but the neural part, in philosophical
anatomy. It is the region in which the great centres of the nervous
system are placed. The termination (_a_) is the anterior or oval part;
the other end (_b_), the posterior or anal part: between these
extremities the intestines take a straight course. The neural surface
is that upon which the majority of molluscs move, and by which they are
supported, and it is commonly modified to subserve these purposes by the
formation of a muscular expansion or disk, called the foot. Three
regions, in many genera very distinctly divided from one another, may be
distinguished in this foot: an anterior, the _Propodium_ (_p p_); a
middle, the _Mesopodium_ (_m s_); and a posterior, the _Metapodium_ (_m
t_). In addition to these, the upper part of the foot, or middle portion
of the body, may be prolonged into a muscular enlargement on each side,
just below the junction of the hæmal with the neural region, the
_Epipodium_ (_e p_). The mass of the body between the foot proper and
the part of the abdomen which bears the epipodium may be termed the
mid-body, or _Mesosoma_. On the upper part of the sides of the head are
two pairs of organs, namely, the eyes and tentacles. In the hæmal region
the integument may be modified and raised up into a fold at the edges,
either in front or behind the anus. When so modified, it is called a
mantle, _Pallium_. In front of the anus again, the _branchiæ_ (_t_)
project as processes of the hæmal region. Among the internal organs, the
heart (_u v_) lies in front of the branchiæ in the hæmal regions, the
nervous ganglia (_x_ _y_ _z_), of which there are three principal pairs,
being arranged around the alimentary canal, which they encircle.

Such is the general type of the class Mollusca, of which, however, the
variations are innumerable. They are all soft-skinned animals, without
either articulated exterior or annular external skeleton. Their nervous
system, being without cerebro-spinal axis, is entirely composed of
ganglions, which are all reunited in the oesophagus without constituting
in any case a lengthened median chain. Their digestive organs are
complete--that is, they are provided with two apertures; their principal
organs are symmetrical and according to a plan, usually curving, by
which their bodies are divided into two parts.

The first series or subdivision, to which Milne Edwards has given the
name of _Molluscoïda_, includes under that term the Bryozoaires,
Ascidians, and Tunicata.



CHAPTER X.

MOLLUSCOÏDA.


The Bryozoaires, or Polyzoa, as British naturalists prefer to call them,
form the boundary-line which divides the humble mollusc from the humbler
zoophytes. In consequence of this intermediate organization, these
creatures were long considered as polyps; but De Blainville, Milne
Edwards, and Ehrenberg, almost simultaneously began to separate them
from the molluscs, and form them into a separate group. Subsequent
naturalists, while considering the Molluscoïda as truly and wholly
molluscous, admit that the distinction proposed by the French
naturalists is most important, and should be retained as a primary
subdivision, confining it to those molluscs which have the neural region
comparatively little developed, and the nervous system reduced to a
single or at most a pair of ganglia, and the mouth surrounded by a more
or less perfect circle of tentacles: an arrangement which would include
the _Brachiopoda_ with the _Polyzoa_.

Marine plants are sometimes observed to be quite covered with a velvety
parasitic matter, which may at a first glance be mistaken for a moss.
This, however, is simply an aggregation of animalcules, each of which
has its separate cell, which is placed quite contiguous to its
neighbour.

These little creatures are thus entirely distinct. Each cell is formed
by the skin, which has been encrusted by calcareous salts, or other
organic matter, hardened after the manner of a horn. This kind of shell
protects the animal from the attacks of its enemies. This mode of
retreat at the bottom of a protecting shelter is very frequently adopted
in the whole series of molluscs. The oyster shuts itself up by closing
its valves, and the snail retires into its shell. This assemblage of
small cells presented by the Bryozoaires has long been known as a
coral. "We propose," says our author, "with very good reasons, to call
it a _Testier_, or shell-builder."

This testier, in which each shell has its opening, is furnished with a
naked cushion, dentate, spinous, or protected by an operculum or lid,
and presents itself under every variety of form. It is sometimes an
assemblage of branching tubes, occasionally a rounded mass of spongy
appearance, and now it presents itself as a flat lamelliform
inarticulated expansion. In some of the marine species the shell of the
mussel is covered as with a fine lace.

It is a remarkable fact that these cells are not always inert. They seem
to enjoy the power of motion. It is well known that the leaves and
branches of the sensitive plant (_Mimosa_) contract and expand under the
touch of the finger; the same phenomenon, according to Mr. Rymer Jones,
takes place on touching the cells of certain species of Bryozoaires. The
moment they are touched they quickly incline themselves; and the
movement is immediately communicated from one to the other, until all
the cells of the community are in motion.

Returning to the organization of the little creature which occupies the
cell, it is found that the upper and retractile portion, which is of
extreme delicacy, terminates anteriorly in a circle of long tentacles,
in the centre of which is the mouth. These tentacles are fringed
laterally by a series of vibratile cilia. "When the animal displays
itself," says Frédol, "this circle of microscopic threads of extreme
tenuity first show themselves rising from the summit of the cell; this
is followed by the upper part of its body, which is more or less
flexible; the tentacles follow between the threads, pushing them on one
side."

These tentacles are furnished on the back with a dozen appendages like
very fine hairs, attached to them nearly at right angles, in addition to
the lateral cilia already spoken of, which play a very important part in
the arrangements of most microscopic animals. At the moment when the
tentacles appear outside the cell, the tunic of the animalcule, which
has the power of expanding or contracting itself, is gradually unrolled.
It soon spreads out its pretty little arms, the appendages and cilia
beginning their rapid vibrations, until the eye, deceived by the
rapidity and regularity of their movements, is dazzled, and the beholder
begins to think that he sees rosy drops of dew waving to and fro,
twisting and untwisting themselves. The corpuscles which float round the
animal are violently agitated, as if they were under the influence of
some strong breeze. Unhappy, indeed, is the fate of the unfortunate
infusoria which chance leads at this moment into the fatal circle.

In many species, observers have discovered a special organ called the
_vibracule_, which deserves our attention for a moment. It is a hollow
filament, situated at the upper and outer angle of each cell, filled
with a substance which is at once fibrous and contractile, admitting of
some very remarkable movements, which occur regularly, and generally at
very short intervals. At first the filament inclines itself towards the
base, trembles, oscillates, and seems to sink; presently it recovers
itself, and inclines in the opposite direction, where it repeats the
same operation with the same order and in the same time. "What are the
functions thus performed?" asks Frédol. "Are they, we would ask,
independent up to a certain point of the will of the Bryozoaire? What is
their purpose?" We think he answers, "That this organ serves the purpose
of cleansing, and especially that of strengthening, the entrance to the
cell. It even continues its movement after the animal has been mutilated
or killed. The poor sickly or dead creature continues to be defended by
its protecting vibracule."

The prey which is drawn into the vortex by the tentacles and their
appendages enters into the mouth, to which is attached a pharynx,
oesophagus, stomach, and intestines. In the back or hæmal region, not
far from the mouth, there is a special opening for this intestine.

Respiration is provided for in the Bryozoaires by the ciliate appendages
which surround the mouth; they are at once tentacula and branchiæ. The
animal presents no other trace of organs of the senses. A small ganglion
and a few fillets constitute all of the nervous system which can be
traced; neither heart nor blood-vessels have been found.

The egg, in the case of the Bryozoaires, gives birth to a young animal
covered with hairs on its surface; it swims about freely until it has
chosen a convenient place in which it can establish the new colony which
it is to originate. But this choice is not made for itself alone; the
young animal encloses under its hairy envelope two new individuals,
which, young as they are, have already the appearance of adult
Bryozoaires. At first, these only increase the number of the colony by
budding, but in a short time they produce eggs.

From these remarks it will be seen that the animals of the Bryozoaires
are more complex in their form and functions than those of the coral,
and the study of their anatomy confirms this conclusion. In their case
the digestive organs are no longer a simple sac with a single orifice;
there is a mouth, a pharynx, a gullet, a gizzard, a membranous stomach
and intestines, with a special opening. We have descriptions of some
species in which the gizzard seems to be provided with a certain number
of interior teeth forming a wonderful pavement--a living mill for the
purpose of grinding the food before it enters into the second stomach.
The organization of this small creature reveals to our eyes a wonderful
amount of combination--of admirable art immeasurably surpassing all that
the most perfect human industry and human genius can accomplish.

After this general view of the organization of the group, we shall
proceed to introduce the reader to some of their more characteristic
species.

Under the leaves of water-lilies (_Nymphea_), pond-weed (_Potamogeton_),
or upon floating fragments of submerged wood, are generally to be found
certain Bryozoaires, animals described by Trembley under the name of
_plumed polyps_. These are _Plumatellæ_ (Fig. 121). These little
diaphanous creatures constitute colonies which under the microscope
resemble small branching shrubs; they consist of small slender tubes
grafted one to the other, and having from forty to sixty retractile
tentacula, which expand like the petals of a flower; they are furnished
with vibratile cilia, the movements of which serve the purpose of
leading food into the mouth.

[Illustration: Fig. 121. Plumatella cristallina magnified (after
Roesel).]

Another genus, which is found in ponds in France, and which is also
found in fresh water in Britain, is the _Cristatella_ of Cuvier.
"Perfect specimens of _C. mucedo_ occur from six lines to twenty-four in
length by two or three in breadth," says Sir J. G. Dalyel, "of a
flattened figure, fine translucent green colour, and fleshy consistence.
Some of the shorter tend to an elliptical form, but those of larger
dimensions are linear, with parallel sides, and curved extremities. The
middle of the upper and the whole of the under surface are smooth, the
former somewhat convex, occasioned by a border of seventy or eighty,
even up to three hundred and fifty, individual polypi, dispersed in a
triple row, their number depending entirely on the size of the specimen.
Each of these numerous polypi, though an integral portion of the common
mass, is a distinct animal, endowed with separate action and sensation.
The body rising about a line above a tubular fleshy stem, is crowned by
a head, which may be circumscribed by a circle as much in diameter, of a
horse-shoe shape, and bordered by a hundred tentacula. Towards one side,
the mouth, of singular mechanism, seems to have projecting lips and to
open as a valve, which folds up within, conveying the particles which
are absorbed to the wide orifice of an intestinal organ, which descends,
perhaps, in a convolution below; and returns again, terminating in an
excretory canal under the site of the tentacula."

The inhabitants of the colony are then united in great numbers under one
common envelope; these are longish filaments of the size of a swan's
feather, reminding one of the appearance of the silk thread known by
embroiderers as chenille. The downy appearance is produced by the
collection of tentacula belonging to this curious swarm. The filamentous
mass is the translucent row of cells in which these animalcules are
lodged, and to which they retreat when disturbed. These cells are
sometimes free in part, sometimes completely rooted to the stems of
aquatic plants. The tentacles are of a fine transparent glass colour,
the body being of a brown colour. Fig. 122 represents _Cristatella
mucedo_, which is common both in this country and in France.

[Illustration: Fig. 122. Cristatella mucedo (Cuvier).]

Most naturalists have now agreed to place among the Bryozoa certain
species of animalcules which long remained imperfectly known. Amongst
these are the _Flustra_, the _Eschara_, and other ascidians.

The Flustra are marine Bryozoa, whose skin in hardening forms a thin
shell of horny or cellular appearance; their little cells, more or less
horny, are grouped symmetrically, somewhat like the cells in a bee-hive.
Sometimes they form a crust which covers the algæ and other submarine
bodies; sometimes they form ribbon-like stems. In some species the cells
are only found on one side; in others they occupy both. Their orifices
are extremely small, and defended by spines quite microscopic (Fig.
123).

[Illustration: Fig. 123. Flustra foliacea (Linnæus).]

Their tentacles are covered with cilia, always vibratile, disposed in a
straight line, which in their movements produce the effect which a row
of animated pearls might be supposed to produce if rolled upwards from
the base to the summit of the organ.

The Eschara form leaf-like expansions, the entrance to their cells
having also their protecting spines.

The expansions still represent microscopic bee-hives, the inhabitants of
which enjoy at once a common and an independent existence. As it is
with the corals, so it is here; each eats for the benefit of itself and
for the community. Labour and nutrition for the community, labour and
food for itself.


TUNICATA.

On seeing one of the _Tunicata_ for the first time, a stranger to
zoology would scarcely take them for animals at all. Almost always
attached to submarine rocks, these beings have the form of a simple sac.
Their skin, gelatinous, horny, or rock-like, is at times covered with
marine plants and polyps. They have neither arms, nor feet, nor head.
But then they have a mouth, placed at the entrance of a digestive tube,
and, in connection with the latter, a special opening intended for
evacuations. The mouth is preceded by a great cavity, the walls of which
are covered with vessels; for this cavity is the seat of respiration,
and is covered with vibratile cilia. Thus the same canal serves first
for respiration, and then, farther on, for digestion: another instance
of the economy of Nature. Another remarkable instance of circulation is
found: they have a heart, but no head.

This heart is the centre of a well-developed vascular system, but very
unlike what usually obtains. The blood which traverses it takes such a
course, that, in the space of a very few minutes, the heart changes its
aurical into ventrical and its ventrical into aurical blood. At the same
time the arteries are changed into veins and the veins into arteries.
The consequence is, that the current which traverses these canals
changes its direction with each contraction of the heart.

Simple as is their organization, the Tunicata have a nervous system. It
is an unique ganglion, connected with divers small fillets. The organs
of sensation present themselves in a very rudimentary fashion. We find
eyes, and, after very minute search, a single ear has been found. They
are propagated by budding, and also from eggs. The young are subject to
some very curious metamorphoses, some particulars of which will be given
farther on.

The Tunicata are divided into _Ascidia_ and _Salpa_, to which some
naturalists add the _Brachiopoda_.


ASCIDIANS.

The _Ascidia_, from the Greek word ἀσχιδίον, leather bottle, have, as
the name indicates, the shape of a bottle or purse. The analogy becomes
more evident when it is considered that these creatures are habitually
filled with water, which can be expelled by very slight pressure.

The Ascidians are sometimes free, sometimes united to others in a manner
more or less intimate. Hence their division into the three groups of
_simple_, _social_, and _composite_ Ascidians.

[Illustration: Fig. 124. Ascidia microcosmus (Cuvier).]

Simple Ascidians attach themselves, each individual singly, to rocks and
other submarine bodies, and generally at a fixed depth. _Ascidia
microcosmus_ a Mediterranean species, represented in Fig. 124, may be
quoted as a type of this division of Ascidians. The name of Microcosmus,
or the little world, is probably given from its being inhabited by quite
an animated colony of algæ and corals, which dwell upon its surface, and
give it a very peculiar, but not very attractive, appearance. The
flavour of these molluscoids is very strong, which does not, however,
hinder the poorer dwellers on the sea shore from eating them. The genus
_Phallusia_ is another type of the group. _Phallusia grossularia_ is of
a reddish colour, and about the size of a currant-berry: it usually
lodges itself in the oysters of certain localities. At Ostend another
species, _Phallusia ampulloïdes_, is found in prodigious quantities in
the oyster parks, and is parasitic on living lobsters.

Social Ascidians comprehend living _Tunicata_, connected together on a
common prolongation by the roots, but free and unconnected in all other
respects. _Ascidia pedunculata_ (Fig. 125) may be quoted as an example.

The Composite Ascidians are still more intimately associated together; a
great number of these little beings live together in a single mass. Such
are the Botryllus and the Pyrosoma.

The Botryllus is a genera the most interesting of all the groups under
consideration. Only imagine from ten to twenty individuals, oval in
form, more or less flattened, adhering by their dorsal surface to some
submarine body, and holding on by their sides, so as to form a sort of
wheel. "When we excite one of the branches," says Frédol, "a single
mollusc contracts itself; when we touch the centre, they all seem to
contract themselves (Cuvier). The buccal orifice is at the outer
extremity of the radius; but the intestinal terminations abut on the
common cavity, which occupies the centre of the wheel. Here we behold
certain animals which eat separately, but which fulfil together as a
community very singular functions--a kind of union and communism of
which the moral world presents no prototype. With our molluscs, in place
of two individuals united, we have a score. We may consider the entire
star as one single animal with many mouths. But then, we have with it a
luxury of organs for the function of intelligence which seeks and
chooses, and parsimony of the organ of stupidity, which neither seeks
nor chooses."

[Illustration: Fig. 125. Ascidia pedunculata (Milne Edwards).]

While the Botryllus is fixed and adherent, the Pyrosoma, on the
contrary, is perfectly free. The animal colony which constitutes it
floats and balances itself upon the waters, like the sea-pen or the
physalia, of which we have spoken in treating of the zoophytes.

The name Pyrosoma has been given to these animals in consequence of
their brilliant phosphorescent properties. According to the observations
of Péron and Lesueur, nothing can exceed the brilliant and dazzling
light emitted in the bosom of the ocean by these animals. From the
manner in which the colonists dispose themselves, they form occasionally
long trains of fire; but it is a singular fact that this phosphorescence
presents the same curious characteristics that distinguish the cilia of
the Beroë; namely, that the colours vary instantaneously, passing with
wonderful rapidity from the most intense red to yellow, from golden
colour to orange, to green, or to azure blue. Von Humboldt saw a flock
of these brilliant living colonies floating by the side of his ship, and
projecting circles of light having a radius of not less than twenty
inches in diameter. He could see by this light the fishes which followed
the ship's track, during many days, at the depth of from two to three
fathoms.

Bibra, a Brazilian navigator, having caught six Pyrosoma, employed them
to light up his cabin. The light produced by these little creatures was
so bright, that he could read to one of his friends the description he
had written of these his living torches.

Three species of Pyrosoma are known; namely, _P. elegans_, two or three
inches in length, which inhabits the Mediterranean; _P. giganteum_,
which is found in the same sea. It is a long bluish cylinder, bristling
with tubercles, each of which is the abode of an animal, a citizen of
this moving republic, and is attached to its colleagues by means of its
gelatinous envelope: an alliance imposed by inexorable Nature--a forced
species of socialism.

The third species, _P. atlanticum_, was discovered by Péron and Lesueur
in the Equatorial seas.

These curious Ascidians are so created in rings as to constitute a long
fine cylindrical tube, closed at one end and open at the other. By the
contraction and dilatation of the mass of beings, this great cylinder
swims slowly through the open sea, lighting up the ocean with its
phosphorescent light, shining through the water like a glowing fire. Mr.
Bennet thus describes one of these pelagic appearances: "On the 8th of
June, being then in lat. 30° S. and 27° 5' W. long., having fine weather
and a fresh south-easterly trade-wind, and the thermometer ranging from
78° to 84°, late at night the mate of the watch called me to witness a
very unusual appearance in the water. This was a broad and extensive
sheet of phosphorescence extending from east to west as far as the eye
could reach. I immediately cast the towing-net over the stern of the
ship, which soon cleaved through the brilliant mass, the disturbance
causing strong flashes of light to be emitted, and the shoal, judging
from the time the vessel took in passing through the mass, may have been
a mile in breadth. On taking in the towing-net, it was found half filled
with _Pyrosoma atlanticum_, which shone with a beautiful pale greenish
light. After the mass had been passed through by the ship, the light was
still seen astern, until it became invisible in the distance, and the
ocean became hidden in the darkness as before this took place.

"The second occasion of my meeting these creatures was in a high
latitude, and during the winter season. It was on the 19th of August,
the weather dark and gloomy, with light breezes from north-northeast, in
lat. 40° 30' S., and 138° 3' E. long., at the western entrance to Bass's
Straits, and about 8 o'clock p.m., when the ship's wake was perceived to
be luminous, while scintillations of the same light were abundant all
round. To ascertain the cause, I threw the towing-net overboard, and in
twenty minutes succeeded in capturing several Pyrosoma, which gave out
their usual pale green light; and it was, no doubt, detached groups of
these animals which were the occasion of the light in question. The
beautiful light given out by these molluscans soon ceased to be seen;
but by moving them about it could be reproduced for some length of time
after. The luminosity of the water gradually decreased during the night,
and toward morning was no longer seen."

The genus _Salpa_ forms another interesting group of Tunicata.

The Biphora or Salpa (Fig. 126) are long transparent threads of the more
delicate tissues, composed of rows of individuals placed side by side,
and grafted, as it were, transversely: ribbons, in which each animal is
grafted end on end to its sister: double parallel chains of social
creatures, sometimes alternate, sometimes opposite; living chaplets, of
which each pearl is an individual. Each individual presents an oblong
diaphanous or prismatic body, more or less symmetrical, and often
furnished in front, rarely behind, with tentaculiform appendages. So
great is the transparency, that the various organs may be observed
through the skin as they perform their several functions.

Momus, an ancient philosopher, thought it a subject of regret that
Nature had not thought of piercing the body with an opening sufficiently
large for each one to see what was passing in the interior. The creature
which now occupies our attention would surely have satisfied the demands
of our critic: its body is, metaphorically speaking, a house of glass.

[Illustration: Fig. 126. Salpa maxima magnified (Forsk).]

In order to move itself, the Salpa has recourse to a singular artifice.
It introduces water into its body through a posterior opening, furnished
with a valve, which it expels by an anterior outlet situated near the
mouth. It is thus pushed backwards, and swims, as it were, by recoil.
Moreover, it swims with its belly upwards. All the elements of a chain
of Salpas act in concert; they contract and dilate simultaneously; they
advance as a single individual. One of them floats on the surface with
the undulations of a serpent, so that among sailors they have gained the
appellation of sea-serpents. These long, living trains abound in the
Mediterranean, principally towards the African coast, and in the
Equatorial seas. They are inhabitants of the open sea, and live immerged
at considerable depths; but when the nights are calm they show
themselves on the surface. As they spread themselves abroad with a
strong phosphorescent light, they resemble long ribbons of fire,
unrolling their long waving lines in spite of the waves, as in Fig. 127.
What wonders they see who go down into the great deep! What sights are
reserved for the navigator who traverses the Tropical seas during the
silence of night!

When a chain of Salpas is drawn from the water, the rings separate, and
they can no longer be made to adhere. The social bond has been dissolved
by a superior force.

Salpas are sometimes met with, isolated and solitary, whose exterior
conformation differs much from that which is proper to the connected
Salpa; so different, indeed, that it might belong to another type.
Chamisso, Krohn, and Milne Edwards have ascertained that the Biphora is
viviparous, and that each species is propogated by alternate generation,
the young creature being unlike its immediate parent. One of these
generations is represented by the solitary individuals, the other by an
aggregation of individuals. Each solitary Biphora engenders a new
group--a chain; each constituted member of the chain engenders a
solitary Salpa.

[Illustration: Fig. 127. Phosphorescent chain of Salpas on the surface
of the sea.]

Thus a Salpa is not organized like its mother or daughter, but rather
like its sister, its grandmother, or granddaughter--another example of
alternate generation, which has already been discussed in treating of
zoophytes.

Those marine creatures which pass their lives in a forced
community--animals which eat, sleep, or rest always in company--who
abandon themselves together to the soft caresses of the waves,--these
colonies, or, rather, republics of animals, leading constantly the same
monotonous existence,--reveal to us very strange things: an identical
community of sentiments in a crowd of beings riveted by the same
chain--a chain at once physical, intellectual, and moral!



CHAPTER XI.

ACEPHALOUS MOLLUSCA.

    "Sigiliatim mortales, cunctum perpetul."

    APULEIUS.


The Mollusca proper were divided by Cuvier into five great classes:--

I. Lamellibranchiata, or Acephalous Mollusca, often called Conchifera.
II. Brachiopoda. III. Gasteropoda. IV. Pteropoda. V. Cephalopoda.

The name Mollusca indicates the characters which most struck the
ancients: they are soft--in Latin, _mollis_: their flesh is cold, humid,
and viscous. In consequence of their very softness, they are generally
furnished with an apparatus of defence or protection, in the shape of a
calcareous cuirass, called a _shell_. According to the species this test
is a coat of mail, a buckler, or a tower. The mollusc is thus armed and
defended against all attacks from without, nearly after the manner of a
knight of the middle ages; only the knight was not quite shut up in his
armour, while the mollusc is attached to it by indissoluble organic
bonds. "Such a life and such a habitation!" says Michelet. "In no other
creature is there the same identity between the inhabitant and the nest.
Drawn from its own substance, the edifice is the continuation of its
fleshy mantle. It follows its form and tints. The architect has
communicated its own substance to the edifice."

The shell of the Mollusca has been variously appreciated by naturalists.
"We might regard the shell as the bone of the animal which occupies it,"
says a celebrated French naturalist; and then gives expression to a very
different view. "We may say as a general thesis that testaceous
molluscs are animals with whom ossification is thrown out on the
external surface in place of the interior, as in the Mammals, birds,
reptiles, and fishes. In the case of the superior animals the bones lie
in the depths of the body; in the shelled Mollusca the bones are placed
on the superficies. It is the same system reversed."

Other zoologists reject as altogether untenable this assimilative
theory. "The shell which serves as a dwelling and a shelter cannot," say
these authors, "be considered as a skeleton, because it does not assume
the external form of the animal; because it does not attach itself to
the organs of locomotion; and, finally, because it is the product of
secretion, which increases in proportion to the development of the body
itself." This last opinion appears to us to be the most acceptable.

However that may be, from the immense variety of form and size, from the
beauty and brilliancy of their colours, the shells of the molluscs are
among the most attractive objects of natural history. Nor is it from
their beauty alone that a fine collection of shells becomes interesting:
a living creature has inhabited the shell, a creature which in its
organization and its life, above all, by its habits, excites in a high
degree our interest, curiosity, and admiration. It has been said that
the shell "is like a medal struck by the hand of Nature to commemorate
climates." In short, the waters of different regions of the globe,
whether fresh or salt, are characterized by the presence of particular
shells; moreover, the comparison of living shells with those which lie
in a fossilized state buried in the depths of the soil is a most
important element of our knowledge touching the origin of the different
beds out of which our globe is constituted.

Thus, we must not shut our eyes to these beings, in appearance so
miserable and obscure, if we would possess a general knowledge of the
animal kingdom. The Creator has endowed them with many wonderful gifts
to embellish their lives, and who would dare to disregard them? Who
could examine and compare their structure without being charmed with the
study? Man, who descends into the depths of the earth in search of the
precious metals--who dives into the deep in pursuit of the treasures it
conceals--who stoops his head over works of art--would surely not refuse
to bend himself for a moment to the sand of the sea, to gather in his
hand, to bring nearer to his eyes, these marvellous works of the Divine
Creator!

The true molluscs are divisible into two great classes: the Acephalous,
or Headless, and those having a head of structure more or less perfect,
which are called Cephalous Molluscs.

The Acephalous or Headless Molluscs are so called from the Greek ἀ,
privative, and κεϕαλὴ, head. They have no head; the body is
surrounded by the folds of the skin; the shell consists of two valves.
Such is a summary description of all the Acephalous Molluscs. They are
sometimes naked, and sometimes enclosed in a shell, whence they are
known as Testaceous Molluscs. They are called _bivalves_, because their
shell consists of two halves, or valves united by a hinge. They are
sheltered in this double carapace as a book is in its cover.

Although they have no head, they can feed themselves, and they reproduce
their kind. They have friendships and enmities, perhaps even passions;
probably these are not very lively, for most of them scarcely ever
change their place, even to make the least movement. Many of them remain
fixed to the rock on which they were hatched, and tumultuous sensations
are not quite compatible with immobility.

The bivalves[8] are found in every sea. The shell of the bivalve is
ovoid, globulous, trigonal, heart-shaped, elongated like a pea-pod, or
flat like the leaves of a tree, having an opening down the ventral side.
In some one valve is flat, the other round and swelling in the centre.
The shell is thus an outer envelope, consisting of two pieces, more or
less corresponding to each other in size and shape (of which the oyster
is an example), formed of carbonate of lime deposited in membranous
cells in its outer layers, the inner layers being composed of thin
coatings of lime deposited in the outer surface of the tissue, called
the mantle leaves. The valves are united to the animal by the insertion
of certain muscles, and by the horny epidermis of the mantle, which
stretches over the edge of the valves. The hinge and ligament which
unite the two valves consist of a dense elastic substance, somewhat
resembling india-rubber; the hinge is formed of teeth, and cavities into
which the teeth fit. The ligament acts in opposition to certain
contractile muscles within, which draw them together, and is placed
either within or without the hinge, or partly both. On separating the
valves, the two leaves of the mantle present themselves. These are thin
delicate leaves, furnished at the margin with sensitive tentacles and
other organs of sense, and with glands sometimes highly coloured. The
use of these organs is thus described by Mr. Rymer Jones:--

"When the animal is engaged in increasing the dimensions of its abode,
the margin of the mantle is protruded and firmly adherent all round to
the circumference of the valve with which it corresponds. Thus
circumstanced, it secretes calcareous matter and deposits it upon the
extreme edge of the shell, when the secretion hardens and becomes
converted into a layer of solid testaceous substance. At intervals this
process is repeated, and every newly-formed layer enlarges the diameter
of the valve. The concentric strata thus deposited remain
distinguishable externally, and thus the lines of growth marking the
progressive increase of size may easily be traced."

"While the margin of the mantle is thus the sole agent in enlarging the
circumference of the shell," the professor continues farther on, "its
growth in thickness is accomplished by a secretion of a kind of
calcareous varnish derived from the external surface of the mantle
generally, which, being deposited layer by layer over the whole interior
of the previously existing shell, progressively adds to its weight and
solidity. There is, however, a remarkable difference in character
between the material secreted by the marginal fringe and that furnished
by the general surface of the mantle membrane. The former we have found
more or less covered by glands appointed for the purpose, situated in
the circumference of the mantle; but as these glands do not exist
elsewhere, no colouring matter is ever mixed with the layers that
increase the thickness of the shell, so that the latter always remain of
a delicate whitish hue, and form the well known iridescent material
usually distinguished by the name of nacre or mother-of-pearl."
(_General Outline_, p. 385.)

The process by which shells attain their beautiful markings is thus
described by Mr. Jones:--"The external surface is exclusively deposited
by the margin of the mantle, which contains in its substance certain
coloured spots, which are found to be of a glandular character, and to
owe their peculiar character to a pigment they secrete, which is mixed
with the calcareous matter; coloured lines are therefore found on the
exterior of the shell wherever these glandular organs exist. Where the
deposition of colour is kept up throughout the process of enlargement,
the lines are unbroken and perfect; but where the coloured matter is
furnished only at intervals, spots and patches of irregular form and
increasing in size with the enlargement of the mantle are the
consequence."

Bivalves move about and change from place to place by means of an
extensible fleshy organ called, from some of its functions, a foot; in
fact, it has less resemblance to a foot than to a large tongue. It is a
muscular mass, capable of being pushed out from between the mantle and
the valves, and varies much in form; it is in turn a hatchet, a
ventilator, a pole, an awl, a finger, and a sort of whip. This foot is
simple, forked, or fringed. In some species the tissues are spongy, and
capable of receiving considerable quantities of water. When the organ
swells, it is elongated and stiff; on the other hand, by suddenly
expelling all the water, it gets small and pliable, and can now return
to its shell. This organ is represented in Fig. 128 (_Donax trunculus_,
Linn.), in which it is singularly developed. This bivalve is found on
the sea shore in shallow water; it buries itself almost perpendicularly
in the sands. They are so abundant on the French side of the Channel and
on the shores of the Mediterranean, that they form a considerable
portion of the people's food. These bivalves have the singular power of
leaping to a considerable height and then throwing themselves to a
distance of ten or twelve inches--a spectacle which may be witnessed any
day at low water. When abandoned by the retreating tide, they try to
regain the sea. If seized by the hand, in order to drag them out of the
sand, aided by their compressed, branched, and angular feet, they give
to their shell the sudden and energetic movement under which the
bounding action takes place.

[Illustration: Fig. 128. Donax trunculus (Linnæus).]

The shell of the Donax is slightly triangular and compressed; its length
exceeds its height; it is regular, univalve, unequally lateral, and its
hinge bears three or four teeth on each valve. The action of these feet
is very simple, and is compared by Réaumur to that of a man placed on
his belly, who, stretching out one hand, seizes upon some fixed object,
and draws himself towards it. There is just this difference, that the
movement of the member in the mollusc is altogether contractile.

Authors have described more than 30,000 species of molluscs, so that our
space only permits us to describe a few families, or rather types of
families.

The arrangement of bivalves now most generally adopted in England is
that of Woodward, as developed in the last edition of his manual of the
mollusca; it is greatly based on that of Lamarck. We have adopted his
arrangement altered from a descending to an ascending scale of
organisation.

The Conchifera are divisible into two sections, Siphonida, from the
animals having respiratory siphons, and Asiphonida, destitute of them.

The solen may be taken as a type of the first, and the oyster of the
second. The division Siphonida is divided into two sub-sections, those
without and those with a pallial line sinuated. The first family of this
section is the Pholadidæ, which includes Teredo, Xylophaga, and Pholas,
animals which possess extraordinary powers of boring; not merely as the
Solens do, through sand, but through the hardest rocks.

The _Teredos_ are marine animals having a special and irresistible
inclination for submerged wood; for while wood exposed to the air
becomes a prey to terrestrial animals, so submerged wood is subject to
invasion by aquatic animals, of which the Teredo is by far the most
formidable. The Teredos in the bosom of the ocean perforate the hardest
timbers, whatever be their essence. The galleries bored by these
imperceptible miners riddle the whole interior of a piece of wood,
destroying it entirely, without the slightest external indication of its
ravages. The galleries sometimes follow the grain of the wood; sometimes
they cut it at right angles; the miners, in fact, change their route the
moment they meet in their way either the furrows hollowed out by one of
their congeners, or some ancient and abandoned gallery. By a strange
kind of instinct, however multiplied may be their furrows or tubes in
the same piece of wood, they never mingle--there is never any
communication between them. The wood is thus attacked at a thousand
diverse points, until it is invaded and its entire substance destroyed.
It is by secret ravages of this kind that the piles and other submarine
constructions upon which bridges are built are often riddled and
perforated. They appear to all outward examination as solid and perfect
as at the moment they were first driven; but they yield to the least
effort, bringing ruin and destruction on the edifices they support.
Ships have been thus silently and secretly mined, until the planks
crumbled into dust under the feet of the sailors. Others have gone down
with their crews, entirely caused by the ravages of these relentless
enemies, which are terrible from their unapproachable littleness.

M. Quatrefages, who has minutely studied the organization and habits of
the Teredos in the Port of Saint Sebastian, reports the following fact,
which will give the reader some idea of the rapidity with which these
dangerous molluscs pursue their ravages:--

"A boat, which served as a passage-boat between two villages on the
coast, went down in consequence of an accident at the commencement of
spring. Four months after some fishermen, hoping to turn her materials
to advantage, raised the boat. But in that short space of time the
Teredos had committed such ravages that the planks and timbers were
riddled and worm-eaten so as to be totally useless."

At the beginning of the eighteenth century, half the coast of Holland
was threatened with annihilation because the piles which support its
dikes and sea-walls were attacked by the Teredo; and it proved no
contemptible foe. Many hundreds of thousands of pounds were expended in
order to avert the threatened danger. Fortunately, a closer attention to
the habits of the mollusc has brought a remedy to a most formidable
evil; the mollusc has an inveterate antipathy to rust, and timber
impregnated by the oxide of iron is safe from its ravages. This taste of
the Teredo being known, it is only necessary, in order to scatter this
dangerous host, to sink the timber which is to be submerged in a tank of
prepared oxide of iron--clothed, in short, in a thick cuirass of that
antipathy of the Teredo, iron rust. Ships' timbers are also served with
the same protecting coating; but the copper in which ships' bottoms are
usually sheathed serves the same purpose.

The singular Acephalous Mollusc known to naturalists as the _Teredo
navalis_, and popularly as the Ship Worm (Fig. 129), has the appearance
of a long worm without articulations. Between the valves of a little
shell, with which it is provided anteriorly, may be seen a sort of
smooth truncature, which surrounds a swelling projecting pad or cushion.
This cushion is the only part of the body of the animal which can be
regarded as a foot. Starting from this point, all the body of the Teredo
is enveloped by the shell and mantle, which form a sort of sheath
communicating by two syphons with the exterior.

The mantle adheres to the circumference of the shell. Above, it forms
two great folds, which may both be swollen by the afflux of the blood,
and acquire considerable size. One of these folds placed in advance,
which is called the _cephalic hood_, is worthy of attention. The tissue
of the mantle is of a greyish tint, very light, and transparent enough,
especially in the young, to permit of the mass of liver, the ovary, the
branchiæ, and the heart being distinguished in the interior, even to
counting its pulsations. The syphons are extensible, and attached the
one to the other for about two-thirds of their length, the upper part
being longer and thinner than the lower. It is by these tubes that the
aërated water enters which feeds and enables the animal to breathe. It
is discharged by the second tube, when deprived of its oxygen, and no
longer respirable, carrying with it the useless products of digestion.
This movement is continuous; but from time to time the animal shuts at
once the orifices of both tubes, and slightly contracts itself.

The shell, seen on the side, presents an irregularly triangular form; it
is nearly as broad as it is long; its two valves are solidly attached
the one to the other, above and below, by the mantle in such a manner as
only to permit of very slight movements. It is coloured in yellow and
brown lines; sometimes it is quite plain. On the upper edge of the
anterior truncature of the body of the animal is the mouth, a sort of
funnel, flat and slightly bell-shaped, furnished with four labial palpi,
a stomach without any peculiar feature, and a well-developed intestine.

[Illustration: Fig. 129. Teredo navalis (Linnæus).]

The heart consists of two auricles and a ventricle, which beat at very
irregular intervals, four or five in the minute. The blood is
colourless, transparent, and charged with small irregular corpuscles.
The act of breathing is accomplished in the branchiæ, or gills, and
mantle. Nevertheless, the one half of the blood returns to the heart
without passing through these branchiæ.

The nervous system is well developed, and consists of a brain, nervous
filaments, and of ganglions, which are distributed in the mantle, the
branchiæ, and the syphon tubes.

The adult animal is surrounded by a sort of sheath, consisting of a
solid mucus, which has sometimes been described erroneously as forming
part of the animal. The Teredo, shut up in this tube, is limited in its
movements; when observed in a vase, its motions are slow and
deliberate--movements of extension and contraction, by the aid of which
it contrives with difficulty to change its place; but nothing indicates
a true creeping movement. In a state of nature, according to M.
Quatrefages, the body of the animal is stretched out to three times its
length without diminishing in any respect its proportional thickness;
the afflux of water penetrating under the mantle, and of the blood which
accumulates in the interior vessels, sufficiently accounting for a
phenomenon which at the first glance is very singular.

The Teredo deposits a spherical greenish-yellow egg. Shortly after
fecundation, these eggs are transformed into larvæ. At first naked and
motionless, these larvæ are soon covered with vibratile cilia, when they
begin to move, at first by a revolving pirouette, afterwards swimming
about freely in the water. When one of these larvæ has found a piece of
submerged wood, without which it probably could not live, the curious
spectacle is observed of a being which fabricates, step by step, and as
it requires them, the organs necessary for the performance of its
functions. It begins by creeping along the surface of the wood by means
of the very long feet with which it is furnished. Then it is observed
from time to time to open and shut the valves of the little embryo shell
which partly envelopes it. As soon as it has found a part of the wood
sufficiently soft and porous for its purpose, it pauses, attacks the
ligneous substance, and soon produces a little pore, or cell, which will
be the entrance to the future canal.

Once fairly lodged in this little cell, the young Teredo is rapidly
developed; it covers itself with a coating of mucous matter, which,
condensing by degrees, assumes a brownish tint, forming a solid
covering, with two small holes for the passage of the syphon tubes. At
the end of three days this covering has become quite solid; it is the
commencement of the organized tube, in which the animal is to be
developed. When secured beneath this opaque screen, the little miner is
no longer exposed to observation; but if his cell is opened at the end
of a few days, it is found that it has secreted a new shell, larger and
more solid than the original one; it is the shell of the adult animal.

The young Teredo, which feeds on the raspings of the wood, increases
rapidly; it passes first from a spheroid form to an elongated shape, and
when its body can no longer be contained in the shell, it projects
beyond the edge, and would find itself naked were it not protected by
its membranous sheath, which adheres to the walls of the ligneous
channel, now the dwelling-place of the animal.

The process by which a creature soft and naked like the Teredo should
break into a solid piece of the hardest wood so quickly, and destroy it
with so much facility, was long a mystery. Until very recently, the
shell was looked on as the implement of perforation. But in that case
the shell should preserve certain traces of its action upon surfaces so
resistant as oak and fir; but the shell, on the contrary, is perfect,
with no signs of friction. On the other hand, the muscular apparatus of
the Teredo is not calculated to put the shell into rotatory action, were
the process a boring one. It does not seem therefore possible to
attribute these perforations to a simple physical action.

[Illustration: Fig. 130. Pholas dactylus having hollowed out a shelter
in a block of gneiss.]

Some naturalists have suggested, in explanation of this phenomenon, that
the animal is furnished with the means of secreting a liquid capable of
dissolving the woody fibre. This has been met by the statement that, in
whatever way the wood is attacked, whether the gallery is excavated with
or across the fibre of the wood, the groove is as exactly and neatly cut
as if it had been perforated by the sharpest tool, and that a corroding
dissolvent could not act with this regularity, but would attack the
harder and more tender parts unequally. This objection, which M.
Quatrefages opposes to the idea of a chemical solvent, appears to us to
admit of no reply. But, while opposing unassailable reasons against two
theories, the learned author does not leave us without a very reasonable
explanation of a very puzzling phenomenon. "Let us not forget," he says,
"that the interior of the gallery is constantly saturated with water;
consequently all the points of the walls which are not protected by the
tube are subjected to constant maceration. In this state a mechanical
action, even very inconsiderable, would suffice to clear away the bed of
fibre thus softened, and, if this action is in any degree continuous, it
suffices to explain the excavation of the galleries, however extensive
their ramifications. Again, the upper cutaneous folds, especially the
cephalic hood already mentioned, having the power of expanding at will
by an afflux of blood, covered with a thick coriaceous epidermis, and
moved by four strong muscles, seems to me very capable of performing the
operation. It appears very probable that it is this hood which is
charged with the removal of the woody fibre, rendering it incapable of
resistance by previous maceration, which may also be assisted by some
secretion from the animal." That the fleshy parts of the mollusc, acting
upon the surface, softened by long maceration in water, is the true
boring implement employed by the Teredo, is, probably, the only
explanation the case admits of; at all events, in the present state of
our knowledge, the explanation of the learned naturalist is the most
reasonable which can be given.

The engraving (Fig. 130) represents _P. dactylus_, which has hollowed
itself a home out of a block of gneiss. This dwelling is a cell just
deep enough to contain the animal and its shell, as represented in Fig.
131. To excavate its cell at the bottom of one of these gloomy retreats
seems to be all that the animal lives for. To ascend to the summit or
sink to the bottom of their narrow house makes up all the accidents of
existence to these strange creatures: the hole they dig is at once their
dwelling and their grave; which is attested both by the rocks of the
past and the present.

In its structure the shell differs notably from other Acephalous
Molluscs, which led Linnæus to place it with the multivalve shells.
Between the two ordinary valves, in short, this shell presents certain
accessary pieces, smaller than the true valves, and placed near the
hinge, as represented in _Pholas dactylus_ (Fig. 131), pieces which
would not be there without a purpose.

[Illustration: Fig. 131. Pholas dactylus (Linnæus).]

The shell is equivalve, gaping on each side, swelling below, very thin,
transparent, and white. The animal is a thick, white, elongated, fleshy
body; its mouth opening anteriorly, throws out a long tube traversed by
two canals or syphons, through one of which the water necessary for the
respiration of the animal is absorbed, and ejected through the other.
Through another opening in the mantle a very thick and short foot is
protruded.

There are three ways of accounting for this creature's method of
boring--the mechanical, the chemical, and the electric; the first being
the one generally held. In this case the animal uses its foot as a
boring tool. The second presumes on the Pholas secreting an acid which
corrodes the rock; the third that it possesses a galvanic battery with
similar powers. It is possible that all these three theories may have a
measure of truth. That the foot of the borer is used is clear. The
luminosity which is so characteristic of the animal is in favour of an
electric current, which is almost always accompanied by chemical
decomposition, which would set free the hydrochloric acid of the sea
water. The small size of the entrance to the chambers of the Pholas is
accounted for by the increase of its size during its residence there. De
Blainville thought that a simple movement of the shell incessantly
repeated would suffice to pierce the stone, macerated by the sea water
which passed through the breathing apparatus.

Mr. Robertson, of Brighton, exhibited the living Pholas in the act of
boring through masses of chalk, and thinks the process entirely effected
by the simple mechanical action of the "hydraulic apparatus, rasp, and
syringe."

"If you examine these living shells," says Gosse, "you will see that the
fore part, where the foot protrudes, is set with stony points arranged
in transverse and longitudinal rows, the former being the result of
elevated ridges, radiating from the hinge, the latter that of the edges
of successive growths of the shell. These points have the most accurate
resemblance to those set on a steel rasp in a blacksmith's shop. It is
interesting to know that the shell is preserved from being itself
prematurely worn away by the fact that it is composed of aragonite, a
substance much harder than those rocks in which the Pholas burrows. The
animal," Gosse adds, "turns in its burrow from side to side when at
work, adhering to the interior by the foot, and therefore only partially
rotating to and fro. The substance is abraded in the form of a fine
powder, which is gradually ejected from the mouth of the hole by
contraction of the bronchial syphon."

The Pholades are met with on every sea shore, and are plentiful in the
Channel; on the French coast they are called _Dails_, and sought for
their fine flavour. As examples of the genus, we may quote _Pholas
dadylus_ (Fig. 131); _Pholas candida_, found in the Channel and in the
Atlantic Ocean, which lives buried in the mud or in decayed wood;
_Pholas crispata_ (Fig. 132), also found in the Channel; _Pholas
papyracea_ (Fig. 133); and _Pholas melanoura_ (Fig. 134).

The bodies of many genera of Mollusca have the property of shining in
the dark, but none emit a light more brilliant than that of the
Pholades. Those who eat the Pholades in an uncooked state (which is by
no means rare, for the flavour of the mollusc does not require the aid
of cooking to render it palatable) would appear in the dark as if they
had swallowed phosphorus; and the fisherman who, in a spirit of economy,
supped on this mollusc in the dark, would give to his little ones the
spectacle of a fire-eater on a small scale.

[Illustration: Fig. 132. Pholas crispata (Linnæus).]

The perforations produced in stone by the Pholades have become important
evidence in a geological sense. In many countries there were evident
signs of a considerable sinking of the earth. But in no place is the
evidence of this so clear as in the monument of high antiquity on the
Pozzuolan coast, known as the Temple of Serapis.

[Illustration: Fig. 133. Pholas papyracea (Solander).]

[Illustration: Fig. 134. Pholas melanoura (Sowerby).]

In speaking of the culture of oysters by the Romans, we shall have
occasion to mention the disappearance of the Lucrin Lake, and its
replacement by an enormous mountain, the Monte Nuovo. Now, Pozzuolo is
situated at the foot of Monte Nuovo. We need not add that the whole
neighbourhood is volcanic. Pozzuolo touches on the Solfaterra, on the
Lake Avernus, and is not far from Vesuvius; and in the bay is the
monument of other days, erroneously called the Temple of Serapis. In
reality it was most probably a thermal establishment, established for
its mineral waters, although the world has agreed to call it a temple.

However that may be, the building has been nearly levelled by the hand
of time, aided by the hand of man; and the ruins now consist of three
magnificent marble columns of about forty feet high. But the curious and
important fact is, that these three columns, at about ten feet above the
surface, are riddled with holes, and full of cavities bored deeply into
the marble, and these borings occupy the space of three feet on each
column. The cause of these perforations is no longer doubtful. In some
of the cavities the shell of the operator is still found, and it seems
settled among naturalists that it belongs to a species of Pholas,
although M. Pouchet, a naturalist of Rouen, denies this. "As far," he
says, "as I have been able to judge from the fragment which I extracted
from this temple, which is destitute of the hinge, it is infinitely more
probable that this mollusc is a species of the genus _Corallisphaga_."
In spite, however, of M. Pouchet's scepticism, the mass of evidence is
opposed to his theory.

There are two modes of explaining the fact to which we have called
attention. To enable the stone-boring molluscs which live only in the
sea to excavate this marble, the temple and columns must have been
buried several fathoms deep in sea-water. It is only in these conditions
that the borers could have made an incision, and laboured at their ease,
in the marble column.

But since the same traces of perforation are now visible ten feet above
the surface, it follows that, after being long immersed under water, the
columns have been elevated to their present position. The temple has
been restored to its primitive state, carrying with it, engraved in
marble, ineffaceable proofs of its immersion. Sir Charles Lyell has
consecrated a long chapter to the successive sinking and elevation of
this temple, which proves the fact most conclusively.

       *       *       *       *       *

Family two, the Gastrochænidæ, is a somewhat heterogeneous one, as it
contains Saxicava and Aspergillum. We have only space for a short
account of the latter, the animal which has received the strange name
of the Watering Pot, and is represented in Fig. 135. It inhabits a
calcareous tube, thick, solid, of considerable length, and nearly
cylindrical, presenting at one extremity an opening fringed with one or
many foliaceous folds in the form of frills, and at the other extremity
a convex disk, pierced with holes like a watering-pot: whence its name.
The animal is attached by certain muscles to the interior of the tube.
Chenu, to whom we are indebted for our information respecting this
curious mollusc, tells us "that the animal which inhabits this curious
shell was first described by Russell, whose account of it is deficient
in the anatomical details, which might explain the utility of the holes
in the disk of the central fissure, and of the spiriform tubes found
there." We suppose that this arrangement is necessary in order to
facilitate respiration; and M. De Blainville thinks the small tubes are
intended for the passage of the fillets which are necessary to fix the
animal to the body on which it is to live, and in such a manner as to
admit of its movements round a fixed point.

[Illustration: Plate XX.--Temple of Serapis at Pozzuolo.]

[Illustration: Fig. 135. Aspergillum vaginiferum (Lamarck).]

The animal which inhabits the _Aspergillum_ is elongated, contractile,
and only occupies the upper part of the tube, but it can stretch itself
out sufficiently for all its wants. Shells of this genus are very rare,
although a great number of species are known. They are found in the Red
Sea, and in the seas of Australia and Java. The shells are generally of
a white or yellowish tint; some have the tube covered with a glutinated
sand, mixed with small fragments of shells of diverse colours. We know
nothing of their habits, and their singular forms have left naturalists
in doubt as to the place which should be assigned to them in the method
of arrangement. It is only after having recognized the existence of two
valves, which was detected with great difficulty just under the disk,
and forming part of the sheath in which the animal is encased, that it
has been decided to range them with the _Tubicola_, and with the shells
presenting an arrangement analogous or equally singular. These molluscs
are, as M. Chenu says, little known, rare, and hence much sought for by
collectors. They are exclusively exotic, the most common species being
from Java. It is imported into Europe by the Dutch. Our third family,
the Anatinidæ, includes Myochama, Pandora, Lyonsia, Myacites,
Pholadomya, Thracia, and Anatina, genera which were more important in
the former than in the present seas; some, in fact, being wholly
extinct, or represented, as in Pholadomya, by one or two living species.
Our fourth family, the Myacidæ, including Gycimeris, is found only in
America; Panopaæ, now principally extinct; Thetis, Neæra, Corbula, and
Mya, or Gaper.

Our fifth family, Solenidæ, contains the Solens, which under the name of
"razor-fish" are so abundant on the sandy shores of all parts of the
globe. These molluscs live buried vertically in the sand, a short
distance from the shore; the hole which they have hollowed, and which
they never quit, sometimes attains as much as two yards in depth; by
means of their foot, which is large, conical, swollen in the middle, and
pointed at its extremity, they raise themselves with great agility to
the entrance of their hole. They bury themselves rapidly, and disappear
on the slightest approach of danger.

When the sea retires, the presence of the Solen is indicated by a small
orifice in the sand, whence escape at intervals bubbles of air. In order
to attract them to the surface, the fishermen throw into the hole a
pinch of salt; immediately the sand becomes stirred, and the animal
presents itself just above the point of its shell. It must be seized at
once, for it disappears again very quickly, and no renewed efforts will
bring it to the surface a second time. Its retreat is commonly cut short
by a knife being passed below it; for it burrows into the ground with
such velocity that it is difficult to capture it with the hands alone.

This shell has by some been compared to a knife-handle; by others to a
razor, which has become its popular name. It is a thin, transparent,
long, and slender equivalved bivalve, with parallel edges, gaping and
truncated at both extremities. The tints are rose-coloured, bluish-grey,
and violet; the valves slightly covered with an epidermis of a greenish
brown.

The animal which lives in this elegant dwelling has the form of an
elongated cylinder. Its mantle is closed in its whole length, and only
open at the ends at one side for the passage of the food, and at the
other for the passage of a tube formed of two syphons united together.
This curious shell, various species of which are represented in PL.
XIX., are known as razor-fish, sabre-fish, and other names, which in
some respects indicate the peculiar form of the shell, as well as its
sharpness.

[Illustration: PLATE XIX.--Razor-fish. Solenidæ.

    I. Solen siliqua. (Linn.)
    II. Solen vagina. (Linn.)
    III. Solen ensis. (Linn.)
    IV. Solen ensis major. (Lamarck.)
    V. Solen ambiguus. (Lamarck.)
    VI. Solen legumen.
]

The Tellinidæ, the sixth family in our table, is very important, as
including a vast number of genera and species, of which, as types, we
will particularise Tellina and Donax; but Galatea, Mesodesma, Semele,
Sanguinolaria, Psammobia, and Capsula, are important genera.

Along the shores of the Channel and in the Mediterranean there are few
bivalves more abundant than the several species of the genus _Donax_.
They live near the shore in shallow water, burying themselves
perpendicularly in the sand. They have the very singular habit,
considering their apparent helplessness, of being able to leap to a
certain height and then project themselves ten or twelve inches. This
may often be witnessed in the case of individuals left by the retreating
tide. If seized by the hand, and attempts are made to disengage them
from the sand, they continue to impress on their shell a sudden and
energetic movement, aided by the elasticity of their foot, which is at
once decisive and angular.

[Illustration: Fig. 136. Donax rugosus (Linnæus).]

[Illustration: Fig. 137. Donax denticulatus.]

The shell of the _Donax_ is nearly triangular in shape, compressed,
longer than it is high, regular, equivalve, not equilateral; the hinge
with three or four teeth on each valve.

The animal is slightly compressed, and more or less triangular. Its
mantle, which forms two symmetrical lobes enveloping the body, is open
pretty nearly in all its extent, but it is united posteriorly, and
terminates in two syphons or nearly equal tubes, as in Fig. 130, p. 326.
One of these tubes serves the purpose of respiration: it is the
_bronchial syphon_. The other, serving the purpose of ejecting the
products of digestion, is termed the _anal_ tube. The tentacles of the
bronchial tube seem to be possessed of exquisite sensibility. When
touched, the animal draws in its syphon, and only puts it forth anew
when the danger has passed. The species of _Donax_ are very numerous,
especially in the Asiatic and American seas. Among the European species
we may mention _Donax rugosus_ (Fig. 136) and _Donax denticulatus_ (Fig.
137).

[Illustration: Fig. 138. Tellina radiata (Linnæus).]

[Illustration: Fig. 139. Tellina virgata (Linnæus).]

[Illustration: Fig. 140. Tellina sulphurea (Lamarck).]

[Illustration: Fig. 141. Tellina donacina (Linnæus).]

Next to _Donax_ naturalists rank the genus _Tellina_, which includes
many species of very minute shells, all remarkable for their beauty of
form, and for their brilliant and varied colours. One of these, called
the Rising Sun (_Tellina radiata_), is represented in Fig. 138. The
Tellinas are found in every sea; the French coast furnishes many
species: examples, _Tellina virgata_ (Fig. 139) and _Tellina sulphurea_
(Lamarck) (Fig. 140). In Fig. 141 _Tellina donacina_ is represented with
its two vital tubes, or syphons.

The seventh family, or Mactridæ, include Lutraria and Mactra, or the
otter and kneading-trough shells. They are widely distributed; there are
several British species of both.

The eighth family, Veneridæ, includes Venus, Cytherea, Meroe, and
Artemis; beautiful genera, and as such called by Linnæus and his
followers after heroines of Greek mythology. Petricola, Venerupis,
Tapes, Lucinopsis, and Trigona, also belong to the family. These
acephalæ of size so small, like their congeners, inhabit every sea; they
are found in every region of the globe, more than a hundred and fifty
species being known. The shell is elliptic in form, the valves smooth,
striated, spiny, and lamellous, like those of Cardium and Donax. Like
these, they bury themselves in the sand.

[Illustration: Fig. 142. Venus verrucosa (Linnæus).]

[Illustration: Fig. 143. Cytherea geographica (Chemnitz).]

Among the vast number of species, many of them are extremely rare, and
much sought after by collectors in consequence of their great beauty. In
the principal ports of France, _Venus verrucosa_ (Fig. 142), and another
species known in the south of France under the name of Clovisse, are
eaten there like oysters. Prepared with fine herbs, the Clovisse, we
have M. Figuier's authority for saying, is not to be despised. "We may
be believed also," he says, "if we add that nothing is more delicious
than to eat the living Clovisse torn from the rock of the Phara of Lake
Thau, when the Mediterranean sun of a day in winter is shining down upon
us, the heart rejoicing in manhood's strength." In PL. XVIII. some of
the principal species are represented, along with some of the more
remarkable species of _Cytherea_. In Fig. 143 we have the elegantly
pencilled shell of _Cytherea geographica_, together with the animal in
its natural connection.

The sub-section we shall now treat of is without the pallial line
sinuated. The Cyprinidæ form the ninth family of our arrangement of the
Conchifera, and contain, Cardia, Cypricardia, Isocardia, Crassatella,
Astarte, Circe, and Cyprina, which amount together to some hundred
species.

The Cycladidæ are our tenth family, and include Cyrenoides, Cyrena,
Pisidium, and Cyclas.

The Lucinidæ is the eleventh family, containing Galeomma, Lepton,
Montacuta, Kelia, Diplodonta, Corbis, and Lucina.

In the small family of which we have made the Tridacna the
representative, as well as in some preceding families, the mantle of the
animal is more or less largely open, but never with such a prolongation
as to form tubes. In the _Cardiums_, now under consideration, as well as
_Donax_, _Tellina_, and _Venus_, the respiratory organs are somewhat
modified, so as to adapt them to the habits of the animal. All these
molluscs live buried in the mud or sand, and two great tubes issuing
from the interior of their bodies bring the atmospheric air into
communication with their respiratory organ--namely, the _branchial
leaves_.

The twelfth family, Cardiadæ, contains the familiar
cockles--Cardium--which is derived from καρδὶα, _a heart_, which
they are supposed to resemble in form, are amongst the most
widely-distributed of shells. The shell is convex, as we see in _C.
hians_ (Fig. 144), somewhat heart-shaped, equivalved, the edges dentate
or corrugated, the hinge furnished with four teeth upon each valve. The
accessary ornaments vary with the species, some being smooth, as in
_Cardium Greenlandicum_, Chemnitz (Fig. 145); others, and by far the
greater number, are furnished with regular sides, generally obtuse,
sometimes in ridges diverging from the point and armed with straight or
curved spines, arranged in the oddest manner, as in _Cardium aculeatum_
(Fig. 146).

[Illustration: PLATE XVIII.--Venus and Cytherea.

    I. Venus plicata. (Gmel.)
    II. Venus puerpera. (Linn.)
    III. Venus reticulata. (Linn.)
    IV. Venus Gnidia. (Broderip.)
    V. Cytherea zonaria. (Lamarck.)
    VI. Cytherea petechialis. (Lamarck.)
    VII. Cytherea maculata. (Linn.)
]

In _C. hians_ (Fig. 144), the mantle has a large opening in front,
fringed anteriorly with papillæ in the form of tentacula; the
inhabitant of the shell has a very large foot, with a bend or knee
near the middle; its mouth is transverse and funnel-shaped, and
furnished with a triangular appendage. One of the peculiarities in the
organization of these molluscs is its direct connection with their mode
of life. In short, these molluscs, which most commonly live on the sea
shore, and bury themselves in the sand to the depth of four or five
inches, are enabled to breathe, to draw water for their nourishment, and
also to throw off the products of digestion, by having the mantle
prolonged into two tubes, the orifices of which reach to the surface of
the soil. By means of these feet and an extremely curious organ of
locomotion, the Cardiums can at will issue from their holes and re-enter
them. The fishermen of the shore easily recognize the presence of these
animals by the little jets of water which they throw up through the
sands.

[Illustration: Fig. 144. Cardium hians (Brocchi).]

[Illustration: Fig. 145. Cardium Greenlandicum (Chemnitz).]

[Illustration: Fig. 146. Cardium aculeatum (Linnæus).]

[Illustration: Fig. 147. Cardium edulis (Linnæus).]

These molluscs are found in every sea on the globe, and under all
latitudes. Many of them belong to our own and the French coasts, where
they are eagerly sought for by collectors, as well as for food. The
flesh of the animal, however, is coriaceous, and little esteemed. The
species most common on the littoral of the Atlantic is _Cardium edulis_
(Fig. 147), its white or fawn-coloured shell being hollowed out into six
and twenty furrows, forming so many corrugated ripples on its side.

[Illustration: Fig. 148. Cardium costatum (Linnæus).]

_Cardium costatum_ (Fig. 148) is an exotic species which inhabits the
coast of Guinea and the Senegal, the shell of which, white and fragile,
is much sought after by collectors.

The thirteenth family of our table, Tridacnidæ, consists of only eight
or ten species, but it contains the largest of all, the giant Tridacna.
The historian of the wars of Alexander the Great speaks of oysters
inhabiting the Indian Ocean which were more than a foot long; these were
probably _Tridacna_, the shells of which were most likely to be seen by
the Macedonian conquerors. The valves of _Tridacna gigas_ are sometimes
found a yard and a half in length, and weighing five hundred pounds.
Magnificent examples may be seen in the church of Saint Sulpice, Paris,
where they hold the holy water. These beautiful shells were the gift of
the Venetian Republic to Francis I. Under Louis XIV., the curé Languet
had them presented to the church of Saint Sulpice, where they are used
as fonts for holy water. Another pair are exhibited in the church of
Saint Eulala, at Montpelier, but much smaller in size. The shells of
_Tridacna_ are formed, as represented in PL. XVII., of three acute
angles, festooned on their edges by broad sides bristling with white
scales. The hinges have two teeth; the ligament is elongated and
external.

[Illustration: Plate XVII.--Tridacna gigantea, Holy Water Basin in the
Church of Saint Sulpice at Paris.]

The animal of _Tridacna_ is remarkable for its fine colours. _Tridacna
safrana_ is of a beautiful blue round the edges, rayed through a shade
of very pale blue. More in the interior is a row of small moons of a
yellowish green; the centre is a bright violet, with brownish
longitudinal punctured lines. "We have at this moment before our eyes,"
say the travellers Quoy and Gaimard, "one of the most charming
spectacles that can be seen, when at a little depth beneath the surface
a number of these animals display the brilliant velvety colours and
varying shades of their submarine parterres. As we can only perceive the
gaping opening of the valves, we may imagine to ourselves what is its
first aspect." The mantle of the animal is closed and ample; its edges
are swollen, and reunited in nearly its whole circumference in such a
manner as to leave only three very small openings--two in the upper
part; the one serves the purpose of discharging the products of
digestion, the other gives entrance and exit to the water necessary for
respiratory purposes. The third opening is in the lower part of the
body, and free; it leaves an opening for the passage of the foot, which
is enormous, and is surrounded with an ample tuft of byssoidal fibres.

[Illustration: Fig. 149. Tridacna squamosa (Lamarck).]

[Illustration: Fig. 150. Tridacna squamosa, on the inside (Lamarck).]

Aided by this silky tuft, the animal attaches itself to the rocks, and
suspends its weighty shell from them. If it is intended to remove those
attached to the sides of the rock, it is necessary to cut the cords of
the tendonous byssus, by which it is held suspended, with a hatchet.

All the species are inhabitants of the Tropical seas. The _Tridacna_
_gigas_ is a native of the Indian Ocean. The flesh, though coriaceous,
and by no means of an agreeable flavour, is a great resource to the poor
Indians. The accompanying representations of _Tridacna squamosa_ (Figs.
149 and 150) will convey a general idea of the genus.

Our fourteenth family, Hippuritidæ, is entirely fossil; but the
fifteenth, Chamidæ, of which the best example is the rugose genus
Charina, is widely distributed in tropical seas.

The very numerous division of shells called Asiphonidæ, possesses
animals without respiratory siphons. The shells we shall now describe
belong to the sixteenth family, Unionidæ, which contain Iridina, Anodon,
and Unio.

The pond mussels, _Anodon_, are found in lakes, rivers, and seas of
almost every region of the globe. Their shells are rounded or oval,
generally very thin, regular, and equivalve, not gaping, the hinges
without teeth, whence their name, from the Greek, ὀδότοϛ, _without
teeth_. These shells are nacred inside, and generally smooth.

The _Anodon cygnea_ (Fig. III., PL. XVI.) is broad, deep, and light, and
is sometimes employed for skimming the cream off milk. The genus is
divided into many groups, the principal forms of which are represented
in PL. XVI.

The river mussels, _Unio_, are, like the Anodon, found in the muddy
bottoms of all countries. The animal resembles the Anodon, but the shell
presents a toothed hinge. The lower face of the valve is nacrous, but
shaded with purplish violet, copreous, and iridescent; the anterior face
is of a green colour, which varies from tender to blackish green.

[Illustration: Fig. 151. Unio littoralis (Cuvier).]

Among the species found in European seas may be noted the Rhine mussel,
a large species, the nacre of which is employed for ornamental purposes.
_Unio littoralis_ (Cuvier), represented in Fig. 151, and the painter's
mussel, _Unio_ _pictorum_ (Fig. 152), employed in the arts to contain
certain colours. Those known as the river mussels are leathery, of an
insipid taste, and scarcely eatable: the finest species are found in the
great American rivers.

[Illustration: PLATE XVI.--Anodonta.

    I. Anodonta angulata. (Lea.)
    II. Anodonta ensiformis. (Spix.)
    III. Anodonta cygnea. (Linn.)
    IV. Anodonta magnifica. (Lea.)
    V. Anodonta anserina. (Spix.)
    VI. Anodonta latomarginata. (Lea.)
]

[Illustration: Fig. 152. Unio pictorum (Linnæus).]

Mussels, as we have seen, produce pearls of moderate value. Linnæus, who
was aware of the origin of the Pintadine pearls, and of pearls in
general, was also aware of the possibility of producing them
artificially from various molluscs. He suggested bringing together a
number of mussels, piercing holes in their shells with an augur in order
to produce a wound, and afterwards leave them for five or six years, to
give the pearl time to form. The Swedish Government consented to try the
experiment, and long did so in secret; pearls were produced, but they
were of no value, and the enterprise was abandoned as unsuccessful.

Scottish pearls were much celebrated in the middle ages, and between the
years 1761 and 1784 pearls to the value of £10,000 were sent to London
from the rivers Tay and Isla; "and the trade carried on in the
corresponding years in the present century," says Mr. Bertram, "is far
more than double that amount." The pearl, according to Mr. Bertram, is
found in a variety of the mussel, which is characterised by the valves
being united by a broad hinge, and having a strong fibrous byssus, with
which it attaches itself to other shells, to rocks, and other solid
substances. "The pearl fisheries of Scotland," he adds, "may become a
source of wealth to the people living on the large rivers, if prudently
conducted." Mr. Unger, a dealer in gems in Edinburgh, having discerned
the capabilities of the Scotch pearl as a gem of value, has established
a scale of prices which he gives for them, according to their size and
quality; and it is now a fact that the beautiful pearls of our Scottish
streams are admired beyond the orient pearl. Empresses and queens, and
royal and noble ladies, have made large purchases of these gems; and Mr.
Unger estimates the sum paid to pearl-finders in the summer of 1864 at
£10,000. The localities successfully fished have been the classic Doon,
the Forth, the Tay, the Don, the Spey, the Isla, and most of the
Highland rivers of note. Scottish pearls are much whiter in colour than
oriental. What tint they have is bluish, while those of the East are
yellowish. Pink pearls are produced by several exotic species of Unio.

Our seventeenth family are the Trigoniadæ, affording Trigonia, of which
so many occurred in the Jurassic period of Geologic History in the
strata of Europe, but of which two or three are alone left alive in the
seas of Australia.

The eighteenth family, the Arcadæ, affords between 200 and 300 species
of the families of Leda, Nucula, Pectunculus, and Arca.

Of the eighteenth family, Arcadæ, we shall only at present instance
Pectunculus.

[Illustration: Fig. 153. Pectunculus aureflua (Reeve).]

[Illustration: Fig. 154. Pectunculus delessertii (Reeve).]

The genus _Pectunculus_ are abundant on the shores of the Mediterranean
and along the Atlantic coast. If we take up at hazard a handful of
shells on any part of the French coast, one-third will consist of
_Pectunculus_. They are found mixed with Cardium, Venus, Razor-fish, and
Pectens. Their round and robust frame attracts much attention. They form
the first of those charming infantile collections which are gathered at
the mother's feet.

The animal which inhabits this pretty shell is moulded on its curvature;
like the shell, it is round and squat; it is furnished with a mouth,
large, and thick for its size, and with double branchiæ. When the animal
is taken alive, it sometimes exudes a thick mucous liquid over the
shell, which has disgusted many a young collector with his capture.

Among numerous species of _Pectunculus_ we note as worthy of
representation: _P. aureflua_, Reeve (Fig. 153); _P. delessertii_, Reeve
(Fig. 154); _P. pectiniformis_, Lamarck (Fig. 155); and _P. scriptus_,
Born (Fig. 156).

[Illustration: Fig. 155. Pectunculus pectiniformis (Lamarck).]

[Illustration: Fig. 156. Pectunculus scriptus (Born).]


FOOTNOTES:

[Footnote 8: The term bivalve as constituting a class must be taken in a
limited sense, for several genera, as pholas for example, have six or
more valves.]



CHAPTER XII.

ACEPHALOUS MOLLUSCA--_continued_.


MYTILIDÆ--THE MUSSEL.

    "Ecce inter virides jactatur mytilus algas."

    _Anthologia._

We shall now consider the nineteenth family or Mytilidæ, which includes
Mytilus, Modiola, Lithodomus, and Dreissena.

[Illustration: Fig. 157. Mytilus edulis (Linnæus).]

The well-known shell of the mussel (Fig. 157, _Mytilus edulis_) is
longitudinal, equivalve, and regular, pointed at the base, with capacity
to attach itself by a byssus; the hinge has no teeth, but a deep furrow,
in which the ligament is located. In the genus _Mytilus_ the byssus is
divided to its base. In _Modiola_ it has a common corneous centre. In
_Pinna_ the anus is furnished with a long angular base. In all these
genera the foot is small, its retractile muscles numerous, and the
byssus large. In _Lithodomus_ the byssus is rudimentary; the muscles are
retractile, equal, and two pairs only. In _Unio_, _Cardium_, and
_Hyria_, the foot is large and not byssiferous.

The animal, as described by M. Chenu, is elongate, oval, the lobes of
the mantle simple or fringed, divided at the edge into two leaves, the
interior being very short, bearing a fringe of small, cylindrical, and
movable fillets; the exterior leaf is united to the shell very near the
edge. The opening by which water and food are introduced supplies the
branchiæ at the same time. The stomach consists of a white membrane,
thin, like opaline, and presenting itself in longitudinal folds; the
liver is granulous, composed of greenish grains more or less deep,
contained in the meshes of a whitish tissue forming a thickish bed,
which surrounds the stomach, the intestines taking the direction of the
median and dorsal line, and beneath the heart are received and terminate
in a small appendage, floating in the cavity of the mantle near the
hinge. The foot is, perhaps, the remarkable organ of the mussel: it is
small, semi-lunar when not in motion, but capable of great elongation,
resembling thus a sort of conical tongue, having a longitudinal furrow
on its side. It is put in motion by several pairs of muscles, all of
which penetrate and are interlaced with the tissue; behind it is the
silky byssus. The mouth is large, and furnished with two pairs of soft
palpi, which are pointed and fixed by their summit. Abdominal masses
emanate, and on each side a pair of nearly equal branchiæ. The
additional muscles, one anterior and small, the other posterior, large,
and rounded. At the base of the foot is a gland which furnishes a
viscous secretion; this viscous liquid is organized and moulded in the
groove of the foot, and forms a thread, and originates the byssus; it is
a bundle of hairs, mane, or thread, which holds on to its shell.

The byssus plays an important part in the organization of the mussel.
While the oyster remains eternally riveted to its rock, until torn from
it by violence, the mussel moves about, and in this motion the byssus is
an active agent. The mussel attaches its byssus to some fixed object,
and drawing upon it, as upon a line, the shell is displaced. The house
is drawn onwards; the animal is in motion. It takes no great strides,
but a fraction of an inch satisfies its desires; it is, however, an
advance upon the oyster, and a lesson in mechanics. The mussel stretches
out its foot, and, at the point chosen, it hooks on a hair of the
byssus; then, withdrawing the foot suddenly, and hauling on the thread,
the animal and shell are moved forward. Every time it repeats this
motion it seems to attach an additional hair, so that at the end of the
four and twenty hours it has used many inches in length of cordage. In
the byssus of some mussels we find as many as a hundred and fifty of
these small threads, with which the animal anchors itself most securely
to the rock. Aided by this cordage, the mussel suspends itself to
vertical rocks, holding on a little above the surface of the water, so
that the shell is smooth and polished as compared with the coarse and
rugged shell of the oyster.

The mussels, like the oysters, are gregarious, and widely diffused over
all European seas. They abound on both sides the Channel, their lower
price having procured for them the name of "the poor man's oyster;" but
it is infinitely less digestible and savoury than its congener.

[Illustration: Fig. 158. Byssus, mantle, and oviduct.

A, right lobe of the mantle; D, rectum; G, branchiæ; H, foot; J,
posterior muscle; L, superior tube; O, heart; P, ventricle; Q, auricle;
X, pericardium; _b_, tentacles; _d_, byssus; _e_, gland of the byssus;
_g_, retractile muscle of the foot; _h_, valves of the mantle; _i_,
oviduct; _j_, orifice of the excretory organ; _k_, internal ditto.]

Many of our readers may think that mussels are found on the shore in a
state of nature, of good size, well flavoured, and fit for the table.
Nothing of the kind! Detached from the rocks and cliffs of the sea,
where it has been growing in a natural state, it is lean, small, acrid,
and unwholesome food; and it is only when human industry intervenes to
ameliorate this child of Nature that it becomes palatable and wholesome
food. In order to trace the ameliorative process by which the coriaceous
flesh of the mussel was rendered tender, fat, and even savoury, we must
conduct the reader back into the middle ages.

Some time in 1236 a barque, freighted with sheep and manned by three
Irishmen, came to grief upon the rocks in the creek of Aiguillon, a few
miles from Rochelle. The neighbouring fishermen who came to the relief
of the crew succeeded with great difficulty in saving the life of the
master, a man named Walton. Exiled upon the lonely shore of the Aunis,
with a few sheep saved from shipwreck, Walton at first supported himself
by hunting sea-fowl, which frequented the shore and neighbouring marshes
in vast flocks. He was a skilful fowler, and invented or adapted a
peculiar kind of net, which he called the _night net_. This consisted of
a net some three or four hundred yards in length by three in breadth,
which he placed horizontally, like a screen, along the quiet waters of
the bay, retaining it in its position by means of posts driven into the
muddy bottom. In the obscurity of the night the wild-fowl, in floating
along the surface of the waters, would come in contact with the net, and
get themselves entangled in its meshes.

But the Bay of Aiguillon was only a vast lake of mud, in which boats
moved with difficulty; and Walton, having arranged his bird-net, began
to consider what kind of boat would enable him most conveniently to
navigate the sea of mud. The flat-bottomed, square-sided boat, known in
our rivers as a _punt_, and on the Norman coast as an _acon_, was the
result. Walton's boat had a wooden frame some three yards long and one
in breadth and depth, the fore part of which sloped down into the water,
in the form of a prow, at a slight angle. In propelling the boat the
rower, who occupied the stern of the punt, knelt on his right knee (as
represented in Fig. 159), inclining forward, with one hand on each edge,
and the left leg outside the boat. A vigorous push with the left foot
gave the frail boat an impulse, under which it rapidly traversed the bay
from one point to the other.

The mussels swarmed in the little bay; and Walton soon remarked that
they attached themselves by preference to that part of the post a little
above the mud, and that those so placed soon became fatter, as well as
more agreeable to the taste, than those buried in the mud. He saw in
this peculiarity the elements of a sort of mussel culture which might
become a new branch of industry. "The practices he introduced," says M.
Coste, "were so happily adapted to the requirements of the new industry,
that, after six centuries, they are still the rules by which the rich
patrimony he created for a numerous population is governed. He seems to
have applied himself to the enterprise, conscious not only of the
service he was rendering to his contemporaries, but desirous that their
descendants should remember him, for in every instance he has given to
the apparatus which he invented the form of his initial letter W. After
due consideration, Walton began to carry out his design. He planted a
long range of piles along the low marshy shore, each pair forming a
letter V, the front of the letter being towards the sea, and each limb
diverging at an angle of forty-five degrees. These posts were driven
about a yard asunder; they were about twelve feet long, six feet being
above water, and interlaced with branches wattled together, so as to
form continuous hurdles, each about two hundred yards long, which are
called _bouchots_. By the assistance of this apparatus, which
intercepted spat which would otherwise have been swept away to sea by
the tide, Walton formed a magnificent collection of mussels; but he did
not abandon his isolated piles. These, being without fascines or
branches, and always submerged, arrested the spat at the moment of
emission."

[Illustration: Fig. 159. Punt or Pirogue of the Marsh.]

The advantages of this system of culture adopted by the Irish exile were
so obvious that his neighbours along the shore were not slow to imitate
his example. In a short time the whole bay was covered with similar
bouchots. At the present time these lines of hurdles form a perfect
forest in the little creek. About two hundred and thirty thousand piles
support a hundred and twenty-five thousand fascines, which, according to
M. Coste, "bend all the year under a harvest which a squadron of ships
of the line would fail to float." There are about five hundred of these
bouchots in the bay, each from two hundred to two hundred and fifty
yards in length and six feet high.

[Illustration: Fig. 160. Isolated piles covered with the spawn of
mussels.]

The isolated piles are without palisades, and are uncovered only at
spring tides. In the months of February and March the spat collected on
them scarcely equals in size a grain of linseed; by the month of May it
will be about the size of a split pea; in July, a small haricot bean:
this is the moment for its transplantation. In this month the
_bouchotiers_, as the men occupied in this culture are called, launch
their punts and proceed to the part of the bay where these piles are
driven. They detach with a hook the agglomerated masses of young
mussels, which they gather in baskets, and carry them to their bouchots.
These bouchots, that is to say, the piles covered with fascines and
branches, are of four different heights, forming, so to speak, four
stages, according to the age and growth of the mussel. Each stage
receives the mollusc suitable to it. In the first stage of its existence
the mussel cannot endure exposure to the air, and remains constantly
under water, except at the period of spring tides. These are gathered in
sacks made of old matting, or suspended in interstices of the
basket-work. "These immense palisades," says M. Coste, "cover themselves
with black clusters of mussels developed between the meshes of their
tissues." At that time the second rows are cleared away to make room for
younger generations; the mussels, which no longer dread the air, are
transported to the more advanced bouchots, which remain above water in
all tides, where they stay till they are fit for market, which usually
happens after ten or twelve months of culture on the more advanced
bouchots.

[Illustration: Fig. 161. Piles, with basket-work, covered with mussels
in a fit state to be gathered in.]

But, in order to prepare for this consummation, they are subjected to a
second and even a third remove. There is no longer any danger in
subjecting them to the air for many hours. From this they pass to a
fourth stage, termed _Amont_ (Fig. 161). From this stage the full-grown
mussel is removed. Under this system of culture the reproduction,
nursing, collecting, and preparing for market, are made simultaneously.
From July to January the mussel trade is in full operation, and the
flesh in perfection. From February to April is the close season; their
flesh is then poor and leathery. It is also remarked that those which
inhabit the upper rows of the wicker-work are of a mellower flavour than
those on the lower ranks, and that the intermediate rows are an
improvement on those which are buried in the mud, although even these
are preferable to mussels gathered on the sea shore in a state of
nature.

M. Coste gives a graphic description of the manner in which this
industry is carried on. "Having supplied the neighbouring villages," he
says, "for the purpose of supplying the more distant cities, the
bouchotiers land their punts, filled with mussels, which their wives
carry into grottoes hollowed out of the cliffs; where they clean and
pack them in hampers, baskets, and panniers, for conveyance by carts or
pack-horses. They depart on their respective journeys at night, so as to
reach their markets at La Rochelle, Rochefort, Surgéres,
Saint-Jean-d'Angely, Angoulême, Niort, Poictiers, Tours, Angers, and
Saumur, at an early hour. A hundred and forty horses and ninety carts
make upwards of thirty-three thousand journeys annually to these cities.
Besides this, forty or fifty boats come from Bordeaux, the isles of Ré
and Oleron, and from the sands of Olonne, making an aggregate of seven
hundred and fifty voyages per annum, distributing the harvest of the
little bay at places where horses could not serve the purpose.

"A bouchot, well furnished, supplies annually, according to the length
of its wings, from four to five hundred charges. The charge is a hundred
and fifty kilogrammes (over three hundred pounds), and sells for five
francs; a single bouchot thus carries a harvest equal in weight to a
hundred and thirty to a hundred and forty thousand pounds, equal in
value to £100; the whole bay probably yielding a gross revenue of
£480,000. This figure, and the abundant harvest which produces it, gives
only a slight idea of the alimentary resources of the sea shore; and
every part of the coast, properly adapted for the purpose, could be
turned to equal advantage. In the mean time, the Bay of Aiguillon
remains a monument of what one man may accomplish."

While commending the mussel as an important article of food, we must not
conceal the fact, that it has produced in certain persons very grave
effects, showing that for them its flesh has the effects of poison. The
symptoms, commonly observed two or three hours after the repast, are
weakness or torpor, constriction of the throat and swelling of the head,
accompanied by great thirst, nausea, frequent vomitings, and eruption of
the skin and severe itching.

The cause of these attacks is not very well ascertained; they have in
turn been ascribed to the presence of copper pyrites in the
neighbourhood of the mussel; to certain small crabs which lodge
themselves as parasites in the shell of the mussel; to the spawn of
star-fishes or medusæ that the mussel may have swallowed. But, probably,
the true cause of this kind of poisoning resides in the predisposition
of individuals. The remedy is very simple: an emetic, accompanied by
drinking plentifully of slightly acidulated beverages.

[Illustration: Fig. 162. Malleus alba (Lamarck).]

[Illustration: Fig. 163. Malleus vulgaris (Lamarck).]

We have now come to the twentieth family, the Aviculidæ, which contains
Avicula, Malleus, Maleagrina, Perna, and Pinna. The shells of the
Hammerheads (_Malleus_) have a rough resemblance to the implement from
which they derive their name. The valves are nearly equal, blackish, and
somewhat wrinkled on the exterior, often brilliantly nacred in the
interior. They are enlarged to the right and left of the hinge, forming
prolongations on each side, which give them the fancied resemblance to
the Hammerhead (Fig. 163). At the same time they grow in a direction
opposite to the hinge, which gives something approaching the handle of
the implement.

This is the first feature which a glance at _Malleus alba_ (Fig. 162)
conveys. The hinge is without teeth, having instead a deep conical
fossette or dimple, for the reception of a very strong ligament which
acts upon the valves. The animal is contained in the interior of the
shell, its mantle fringed by very small tentacular appendages. Only six
actually living species of the genera are known, which are inhabitants
of the Indian Ocean, of the Australian seas, and the Pacific Ocean.

The beautiful diaphanous nacre which embellishes the interior of so many
ornamental cabinets are principally produced by the animal inhabiting
the _Meleagrina_, a bivalve, sometimes designated the _pintadine_, or
mother-of-pearl shell. This bivalve moors itself to the bottom of the
sea by a strong byssus of a brownish colour. The door-posts of the
shells are irregularly rounded in their young days; they are externally
lightly foliated, and ornamented with bands of green and white, which
spring from the summit in rays, and afterwards break off into two or
three slightly scattered branches. In old age they become rugged and
blackish. The shell is in its perfection when about eight or ten years
old, their size being then about six inches in diameter, with a
thickness of about an inch and a quarter.

Nacre is the hard and brilliant substance with which the valves of
certain shells are lined in the interior. This substance is white,
silky, slightly azure, and more or less iridescent. Most of the bivalves
are supplied with nacre; some of them even yield a blue, or blue and
violet pigment. The iridescent _Haliotis iris_, for instance, is an
emerald-greenish blue of changing colour, with reflections of a purple
violet. _Turbo argyrostomus_ (Linnæus) presents a mouth of bright
silvery hue, while _Turbo chrysostomus_ appears in all the glory of
gold; but the Pintadine yields the purest white nacre, as well as the
most uniform, and especially the thickest. This product owes its
brilliant and delicate appearance to the play of light on it in its
highly-polished state. For practical purposes the nacre is separated
from the shell with an instrument; sometimes all the exterior part of
the shell being dissolved away from the precious substance, leaving only
the naked bed of nacre.

[Illustration: Fig. 164. Meleagrina margaritifera (Linnæus).

    Outside of the shell.
    Inside of the shell.
]

[Illustration: Fig. 165. Meleagrina margaritifera (Linnæus).]

But the most interesting of all the nacre-bearing shells is the pearl
oyster (_Meleagrina margaritifera_), the exterior, as well as the
interior, of which is represented in Fig. 164. The interior of the shell
affords the most exquisite pearls; the Esterhazy collection of jewels
afforded many such specimens. This shell is nearly round, and greenish
in colour on the outside; it furnishes at once the finest pearls, under
favourable circumstances, and the nacre so useful in many industrial
arts. Fine pearls and nacre have, in short, the same origin. The nacre
invests the whole interior of the shell of _Meleagrina margaritifera_;
being the same secretion which in the pearl has assumed the globular
form: in one state it is deposited as nacre on the walls of the bivalve,
in the other as a pearl in the fleshy interior of the animal. This nacre
is therefore at once a calcareous and horny matter, which the animal
secretes, and which it attaches to the interior walls of the shell
during the several periods of its development. Pearls are formed of the
same substance, only in place of being deposited upon the valves in
beds, the material is condensed and agglomerated in small spheroids,
which develop themselves either on the surface of the valves or in the
fleshy part of the mollusc. Between nacre and pearls, therefore, there
is only the difference of the form of deposition. Fig. 165 represents
the pearl oyster with calcareous concretions in various states of
progress.

The finest pearls--solidified drops of dew, as the Orientals term them
in the language of poetry--are secretions supposed to be the result of
disease in the animal. The matter, in place of being spread over the
surface of the valves in their beds, is condensed either on the centre
of the valves or in the interior of the organ, and forms a more or less
rounded body. The pearls, when deposited on the valves, are generally
adherent; those which originate in the body of the animal are always
free. Generally we find some small foreign body in their centre which
has served as a nucleus to the concretion, the body being perhaps a
sterile egg of the mollusc, the egg of a fish, a rounded animalcule, a
grain of sand even, round which has been deposited in concentric layers
the beautiful and much-prized gem.

The Chinese, and other Eastern nations, are said to turn this fact in
the natural history of bivalves to practical use in making pearls and
cameos. By introducing into the mantle of the mollusc, or into the
interior of a living valve, a round grain of sand, glass, or metal, they
induce a deposit which in time yields a pearl, in the one case free, and
in the other adhering to the shell. In some cases they are said to be
produced in whole chaplets by the insertion of grains of quartz
connected by a string into the mantle of a species of _Symphynota_; in
other cases, a dozen enamelled figures of Buddha seated have been
produced by inserting small plates of embossed metal in the valves of
the same species.

The pearls are very small at first; they increase by annual layers
deposited on the original nucleus, their brilliancy and shade of colour
varying with that of the nacre from which they are produced. Sometimes
they are diaphanous, silky, lustrous, and more or less iridescent;
occasionally they turn out dull, obscure, and even smoky.

       *       *       *       *       *

The pearl oyster is met with in very different latitudes; they are found
in the Persian Gulf, on the Arabian coast, and in Japan, in the American
seas, and on the shores of California, and in the islands of the South
Sea; but the most important fisheries are found in the Bay of Bengal,
Ceylon, and other parts of the Indian Ocean. The Ceylon fisheries are
under Government inspection, and each year, before the fisheries
commence, an official inspection of the coast takes place. Sometimes the
fishing is undertaken on account of the State, at other times it is let
to parties of speculators. In 1804 the pearl fishery was granted to a
capitalist for £120,000; but, to avoid impoverishing all the beds at
once, the same part of the gulf is not fished every year.

The great fishery for mother-of-pearl Pintadines (_Meleagrina
margaritifera_) takes place in the Gulf of Manaar, a large bay to the
north-east of the island; it commences in the month of February or
March, and continues thirty days, taken collectively, and occupies two
hundred and fifty boats, which come from different parts of the coast;
they reach the ground at daybreak, the time being indicated by a signal
gun. Each boat's crew consists of twenty hands, and a negro. The rowers
are ten in number. The divers divide themselves into two groups of five
men each, who labour and rest alternately; they descend from forty to
fifty feet, seventy being the very utmost they can accomplish, and
eighty seconds the longest period the best divers can remain under
water, the ordinary period being only thirty seconds. In order to
accelerate their descent, a large stone is attached to a rope. According
to travellers the oars are used to rig out a stage, across which planks
are laid over both sides of the boat; to this stage the diving-stone is
suspended. This stone is in the form of a pyramid, weighing about
half-a-hundredweight; the cord which sustains it sometimes carries in
its lower parts a sort of stirrup to receive the foot of the diver. At
the moment of his descent he places his right foot in this stirrup, or,
where there is no such provision, he rests it on the stone with the cord
between his toes. In his left foot he holds the net which is to receive
the bivalves; then, seizing with his right hand a signal-cord
conveniently arranged for his purpose, and pressing his nostrils with
the left hand, he dives, holding himself vertically, and balancing
himself over his foot.

Each diver is naked, except the band of calico which surrounds the
loins. Having reached the bottom, he withdraws his foot from the stone,
which ascends immediately to the stage. The diver throws himself on his
face, and begins to gather all the pintadines within his reach, placing
them in his net. When he wishes to ascend he pulls the signal cord, and
is drawn up with all possible expedition.

A good diver, we have said, seldom remains more than thirty seconds
under water at one time; but he repeats the operation three or four,
and, in favourable circumstances, even fifteen or twenty times. The
labour is extremely severe. On returning to the boat they sometimes
discharge water tinged with blood by the mouth, nose, and ears. They are
also exposed to great danger from sharks, which lie in wait for and
frequently devour the unhappy divers.

They continue to fish till mid-day, when a second gun gives the signal
to cease. The proprietors wait on shore for their boats, in order to
superintend their discharge, which must take place before night sets in,
in order to prevent concealment and robbery.

In past times the Ceylon fisheries were very valuable. In 1797 they are
said to have produced £144,000, and in 1798 as much as £192,000. In 1802
the fisheries were farmed for £120,000; but for many years the banks
have been less productive, and are now said to yield only the sum of
£20,000 per annum.

The natives of the Bay of Bengal, those of the Chinese coast, of Japan,
and the Indian Archipelago, all abandon themselves to the pearl fishery,
the produce being estimated to realize at least £800,000. Fisheries
analogous to those of Ceylon take place on the Persian coast, on the
Arabian Gulf, along the coast of Muscat, and in the Red Sea.

In these countries the pearl fishing does not commence till the months
of July and August, the sea being at that time calmer than in other
months of the year. Arrived on their fishing-ground, the fishermen range
their barques at a proper distance from each other, and cast anchor in
water from eight to nine fathoms deep. The process is pursued here in a
very simple manner. When about to descend the divers pass a cord, the
extremity of which communicates with a bell placed in the barque, under
the armpits; they put cotton in their ears, and press the nostrils
together with a piece of wood or horn; they close their mouths
hermetically, attach a heavy stone to their feet, and at once sink to
the bottom of the sea, where they gather indiscriminately all shells
within their reach, which they throw into a bag suspended round the
haunches. When they require to breathe they sound the bell, and
immediately they are assisted in their ascent.

On the oyster-banks off the Isle of Bahrein the pearl fishery produces
about £240,000; and if we add to this the addition furnished by the
other fisheries of the neighbourhood, the sum total yielded by the
Arabian coast would probably not fall short of £350,000.

In South America similar fisheries exist. Before the Mexican conquest
the pearl fisheries were located between Acapulco and the Gulf of
Tehuantepec; subsequently they were established round the Islands of
Cubagua, Margarita, and Panama. The results became so full of promise
that populous cities were not slow to raise themselves round these
several places.

Under the reign of Charles V., America sent to Spain pearls valued at
£160,000; in the present day they are estimated to be worth £60,000. In
the places mentioned, the divers descend into the sea quite naked; they
remain there from twenty-five to thirty seconds, during which space they
can only secure two or three pintadines. They dive in this way a dozen
times in succession, which gives an average of between thirty and forty
bivalves to each diver.

       *       *       *       *       *

The bivalve is carried on shore, and piled up on mats of Espartero
grass. The mollusc dies, and soon becomes decomposed; it requires ten
days to be thoroughly disorganized. When in a thoroughly corrupt state,
they are thrown into reservoirs of sea-water, when they are opened,
washed, and handed over to the dealers. The valves furnish _nacre_, and
the parenchyma the _pearls_.

The valves are cleansed, and piled up in tuns or casks; by raising their
external surface plates of nacre are obtained more or less thick,
according to the age of the mollusc.

Nacre of three kinds are distinguishable in commerce: silver-faced,
bastard white, and bastard black. The first are sold in cases of two
hundred and fifty to two hundred and eighty pounds; they are brought
from the Indies, from China, and Peru. The ships of various nations
import these shells as ballast. The second is delivered in casks of two
hundred and fifty pounds weight; it is a yellowish white, and sometimes
greenish; sometimes red, blue, and green.

       *       *       *       *       *

Pearls form by far the most important product of the animal. When they
are adherent to the valves they are detached with pincers; but,
habitually, they are found in the parenchyma of the animal. In this case
the substance is boiled, and afterwards sifted, in order to obtain the
most minute of the pearls; for those of considerable size are sometimes
overlooked in the first operation. Months after the mollusc is
putrified, miserable Indians may be observed busying themselves with the
corrupt mass, in search of small pearls which may have been overlooked
by the workmen.

The pearls adherent to the valve are more or less irregular in their
shape; they are sold by weight. Those found in the body of the animal,
and isolated, are called _virgin pearls_, or _paragons_. They are
globular, ovoid, or pyriform, and are sold by the individual pearl. In
cleaning them, they are gathered together in a heap in a bag and worked
with powdered nacre, in order to render them perfectly pure in colour
and round in shape, and give them a polish; finally, they are passed
through a series of copper sieves, in order to size them. These sieves,
to the number of twelve, are made so as to be inserted one within the
other, each being pierced with holes, which determine the size of the
pearl and the commercial number which is to distinguish it. Thus, the
sieve No. 20 is pierced with twenty holes, No. 50 with fifty holes, and
so on up to No. 1000, which is pierced with that number of holes. The
pearls which are retained in Nos. 20 to 80, said to be _mill_, are
pearls of the first order. Those which pass and are retained between
Nos. 100 to 800 are _vivadoe_, or pearls of the second order; and those
which pass through all the others and are retained in No. 1000 belong to
the class _tool_, or seed pearls, and are of the third order.

They are afterwards threaded; the small and medium-sized pearls on white
or blue silk, arranged in rows, and tied with ribbon into a top-knot of
blue or red silk, in which condition they are exposed for sale in rows,
assorted according to their colours and quality. The small or seed
pearls are sold by measure or weight.

In America the bivalve is opened with a knife, like the common edible
oyster, and the pearl is obtained by breaking up the mollusc between the
finger and thumb without waiting for its decomposition; nor is it
boiled. This is a much longer and less certain process than that pursued
in the East; but the pearls are preserved in greater freshness by the
process--for the nacre of the dead shells is less brilliant than that of
those which have been suddenly killed, and at once separated from the
soft parts.

       *       *       *       *       *

Some few pearls have become historical, from their size and beauty. A
pearl from Panama, in the form of a pear, and about the size of a
pigeon's egg, was presented in 1579 to Philip II., King of Spain: it was
valued at £4000. A Lady of Madrid possessed an American pearl in 1605
valued at 31,000 ducats.

The Pope Leo X. purchased a pearl of a Venetian jeweller for £14,000.
Another was presented to the Sultan Soliman the Great by the Venetian
Republic valued at £16,000. Julius Cæsar, who was a great admirer of
pearls, presented one to Servilia which was valued at a million of
sesterces, about £48,000 of our money.

There is no data for the volume or value of the two famous pearls of
Cleopatra; one of these which the queen is said to have capriciously
dissolved in vinegar and drank--Heavens preserve us from such a
draught!--is said by some authors to have been worth £60,000; the other
was divided into two parts, and suspended one half from each ear of the
Capitoline Venus. Another pearl was purchased at Califa by the traveller
Tavernier, and is said to have been sold by him to the Shah of Persia
for the enormous price of £180,000.

A prince of Muscat possessed a pearl so extremely valuable--not on
account of its size, for it was only twelve carats, but because it was
so clear and transparent that daylight was seen through it--he refused
£4000 for it.

In the Zozema Museum at Moscow there is a pearl, called the "Pilgrim,"
which is quite diaphanous; it is globular in form, and weighs nearly
twenty-four carats. It is said that the pearl in the crown of Rudolph
II. weighed thirty carats, and was as large as a pear. This size,
besides being indefinite, is more than doubtful.

The shahs of Persia actually possess a string of pearls, each individual
of which is nearly the size of a hazel nut. The value of this string of
jewels is inestimable.

At the Paris Exposition of 1855, Her Majesty the Queen exhibited some
magnificent pearls; and on the same occasion the Emperor of the French
exhibited a collection of 408 pearls, each weighing over nine
pennyweights, all of perfect form and of the finest water. The Romans
were passionately fond of pearls, and they have transmitted their taste
to the Eastern nations, who attach notions of great grandeur and wealth
to the possessor of large and brilliant pearls.

       *       *       *       *       *

The genus _Pinna_, so called by Linnæus, from one of the species which
was so designated from the resemblance of its byssus to the aigrette or
plumelet which the Roman soldiers attached to the helmet. French
naturalists name them _jambonneau_, from their singular resemblance to a
dried ham (Figs. 166 and 167), their brown, smoky colour not a little
aiding the resemblance. This shell is fibrous, horny, very thin and
fragile, compressed, regular, and equivalve, triangularly pointed in
front, round or truncated behind. The hinge is linear, straight, and
without teeth; the ligament, in great part internal, occupies more than
half the anterior half of the dorsal edge of the shell, forming a
straight elongated fossette.

[Illustration: Fig. 166. Pinna rudis (Linnæus).]

[Illustration: Fig. 167. Pinna nigrina (Lamarck).]

The animal is thick, elongated, with mantle open behind, presenting a
conical furrowed foot, hearing a considerable byssus.

The _Pinnæ_ are found in almost every sea, and at various depths; they
are constantly attached by their byssus, and in a vertical position, the
larger side of their shell being uppermost. They assemble on sandy
bottoms in considerable numbers. The byssus has in all ages fixed the
attention of the Mediterranean fishermen upon these curious shells. With
its tuft of fine silky hairs, six or seven inches in length, of a fine
reddish-brown hue, articles of luxury are formed, which are often
mentioned by the Latin writers. The threads of the byssus, which are
remarkable for their unalterable colour, were formed by both Greeks and
Romans into a fabric to which there is nothing analogous in the world.
The Maltese and Neapolitans still fashion soft tissues from it, but the
stuffs so manufactured are pure objects of curiosity.

[Illustration: Fig. 168. Pinna bullata (Swainson).]

[Illustration: Fig. 169. Pinna nobilis, with its byssus (Linnæus).]

Twelve species are described as living in the several seas. _Pinna
nobilis_ (Fig. 169), the byssus of which was employed in the ancient
Neapolitan industry, inhabits the shores of the Mediterranean. _Pinna
bullata_, Swainson (Fig. 168), is also a well-known species.


OSTREIDÆ.

Our twenty-first family, Ostreidæ, contains Lima, Spondylus, Pecten,
Anomia, and the all-important oyster. The common oyster, _Ostrea
edulis_, is found in all seas. It is unequally valved, modified in shape
by the form of the submarine body to which it happens to be attached.
The lower or adherent valve is concave, always the largest; the upper
one thin, usually flat; the shell is lamellar, rough externally, and
seems to be composed of broken layers, adhering slightly to each other,
as if the successive layers had been built up from within, and each
succeeding layer was an enlargement upon its predecessor. The hinge
which unites the valves is an elastic toothless ligament placed behind
the centre, which opens the valves.

The interior surface of the valves is smooth and white, diaphanous or
pearly towards the centre, but near the back an oval or rounded
impression may be observed, to which a thick and whitish fleshy body is
attached. This is the central muscle which draws the valves together,
hermetically closing them upon the animal. This muscle is cut through in
the process of opening the oyster.

The animal has no power of locomotion; its foot is very small and often
wanting, no syphon, but lies with its mouth open, and slightly attached
to the shell. The shell itself is always adherent, as if soldered to the
rock or other submarine body, the point of adherence being near the
summit of the lower valve, at the part called the _heel_.

Let us suppose the oyster opened by the double dissection of the
ligament of the central muscle and of the abductor valves. When
displayed before our eyes, we see in the bottom of the shell a
flattened, shapeless animal, semi-transparent, greyish, and somewhat
oval-shaped. The gastronomist, who seldom sees beyond his nose, thinks
that in spite of its culinary merits the oyster belongs to the lowest
rank of animal existence; but he deceives himself, and does not know how
complex and delicate is the organization of the humble bivalve. The
animal is enveloped in a sort of smooth, thin, contractile tissue called
the _mantle_, which folds round it, presenting two lobes, separated on
the greatest part of its circumference, and forming a sort of hood, the
summit of which abuts upon the hinge of the bivalve. The edges of this
mantle are fringed with very small cilia, which the creature can extend
and draw back at pleasure, and which seem to be gifted with a certain
amount of sensibility. It is this mantle which secretes and deposits the
calcareous matter which forms the shell, each plate of which is an
enlargement on the preceding one, until it constitutes a pyramid of thin
convex lamellæ.

At the point where the lobes of the mantle meet, near the summit of the
valve, is the mouth of the animal, with its thin membranous lips. This
organ is large and dilatable, and is accompanied by four flat triangular
pieces, by means of which the animal introduces its food into the
stomachal cavity.

A very short gullet is attached to the mouth, which leads to a
pear-shaped stomach. After this stomach comes a slender sinuous
intestine, which, leading obliquely towards the interior, descends a
little, then reascends, passes behind the stomachal cavity, nearly on a
level with the mouth, crossing its first path in order to reach the
posterior face of the adductor muscle, in the centre of which it
terminates with a free opening. The stomach and intestines are
surrounded on all sides by the liver, which alone constitutes a notable
portion of the mass of organs. This liver is of a blackish colour,
pervaded with a deep yellow liquid, which is the bile. Thus the stomach
and intestines of the oyster are surrounded by the _liver_; the mouth is
connected with the stomach, and the intestines open in the back.

The heart of the oyster is placed under the liver, and is surrounded
closely by the terminal part of the intestines. It is composed, like the
same organ in the superior animal, of two distinct cavities, an auricle
and ventricle. From the ventricle issues a vessel, which is divided into
three distinct canals. One of these carries the blood towards the mouth
and tentacles; another carries it towards the liver; the last
distributes the nourishing fluid to the rest of the body. The blood of
the oyster is limpid and colourless; it passes successively from the
auricle of the heart, where it is vivified, into the ventricle, and from
this last cavity into the great vessel of which we spoke, which
distributes it into the interior of the animal.

The oyster thus possesses a true circulation; not that double system
which characterises the mammals, and which includes arterial and
pulmonary action, but a simple circulation, as it exists in fishes and
many other animals. It breathes also in the bottom of the water, after
the manner of fishes, being, like the fish, provided with organs called
gills or _branchiæ_, whose function is to separate the oxygen dissolved
in the water from its other ingredients; these branchiæ, which are
placed under the mantle, consist of a double series of very delicate
canals, placed close together, not unlike the teeth of a fine comb.

Having no head, the oyster can have no brain; the nerves originate near
the mouth, where a great ganglion is visible, whence issues a pair of
nerves which distribute themselves in the regions of the stomach and
liver, terminating in a second ganglion, situated behind the liver. The
first nervous branch distributes its sensibility to the mouth and
tentacles; the second, to the respiratory branchiæ.

With organs of the senses oysters are unprovided. Condemned to a
sedentary life, riveted to a rock where they have been rooted, as it
were, in their infancy, they neither see nor hear; touch appears to be
their only sense, and that is placed in the tentacles of the mouth.

The mode of reproduction in these creatures is very peculiar. The oyster
unites in itself the functions of both sexes. In the same organ are
found the eggs--called _spat_--and the mobile corpuscles intended to
fertilize them.

The eggs are yellowish in colour, and exist in prodigious numbers in
each individual. We are assured that an oyster may carry as many as two
millions of eggs! Nature always makes ample provision for the
preservation of species; but in spite of the most ample provision here
displayed, man, in his reckless and wasteful gluttony, has all but
defeated Nature. A tyro can compute how many individuals a bank of
oysters reckoned at twenty thousand would produce, at the rate of two
millions, or eight hundred thousand, as other authorities assert, from
each one annually, and it will amount to an incredible number--in fact,
each would multiply itself by millions in three years; and yet, thanks
to our improvident management, they get scarcer every year.

The spawning season is usually from the month of June to the end of
September: during this season the oysters deposit their eggs in the
folds of the mantle. During the period of incubation the eggs remain
surrounded by mucous matter, which is necessary to their development,
the whole having the appearance of a thick cream--this milky appearance
being due to the accumulated mass of ova surrounded by the mucus: this
mass undergoes various changes of colour while losing its fluidity,
becoming successively yellowish, greyish, brown, and violet, a condition
which indicates the near termination of the embryo state, for the
oysters do not, like many other inhabitants of the sea, leave their ova;
they incubate them in the folds of their mantle, and only discharge them
when they can live without the maternal protection. Nothing is more
curious to witness than a bank of oysters at the spawning season. Every
adult individual of which it is composed throws out its phalanx of
progeny. A living dust is seen to exhale from the oyster bank, troubling
the water and giving it a thick cloudy appearance, which disseminates
itself little by little in the liquid, until it dissipates and loses
itself far from its focus of production. The _spat_ is soon scattered
far and wide by the waves; and unless the young oyster finds some solid
body to which it can attach itself, it falls an inevitable victim to the
larger animals which prey upon it. In this its infant state, when it
has just left the protection of the parent shell, the microscope reveals
the young bivalve, with its shell perfect, having an apparatus which is
also a swimming _pad_, ready to adhere to the first solid body which the
current drives it against. This pad or cushion (which is represented in
Fig. 170) is furnished with vibratile cilia, disposed round the young
shell. Aided by the powerful adductor muscles, with which it is also
provided, this cushion is projected through the water at the will of the
young inhabitant, which has every facility for the purpose: it is even
said to swim about near the mother, before final dismissal from the
maternal protection, seeking shelter at the least alarm between the
valves of the parent shell. The pad disappears after the young oyster
has finally attached itself to a permanent bed of its own.

[Illustration: Fig. 170. Young Oysters furnished with locomotive
organs.]

Before this period of its life arrives, however, many are the dangers to
which it is exposed: its enemies are numerous; they lie in ambush for it
in every cranny! It has to guard itself against eddies and currents,
which would drive it out to sea, and mud banks, in which it would be
smothered. Crustaceans, worms, and polyps, with other equally voracious
marine inhabitants, prey upon it. Last, but not least, come the terrible
and multiplied engines of the eager fisherman--and we readily comprehend
why the oyster is provided with such accumulated masses of ova.

If the young bivalve is fortunate enough to escape all the snares and
dangers we have enumerated, it grows rapidly. It is quite microscopic at
the period of its discharge from the parent shell; at one month it is of
the size of a large pea, at the end of six months it is about
three-quarters of an inch, a year after its birth an inch and a half to
two inches, and finally, at the end of three years it has become
merchandise; that is to say, it is in a state to be sent to the parks
for preservation and feeding. In Fig. 171 we see a group of oysters,[9]
of various ages, attached to a piece of wood: A being oysters of twelve
to fifteen months, B five or six months, C three to four months, D one
to two months, and E oysters twenty days after birth.

[Illustration: Fig. 171. Groups of Oysters of different ages attached to
a block of wood.]

The species of oysters usually eaten are the common oyster (_Ostrea
edulis_, Linn.) of our own coasts and the opposite shore, and the
horsefoot oyster (_O. hippopus_, Linn.). On the Mediterranean coast are
the rose-coloured oyster (_O. rosacea_, Favanue), and the milky oyster
(_O. lacteola_, Moquin-Tandon), besides the small and little-known
crested oyster (_O. cristata_, Born), and the folded oyster (_O.
plicata_, Chemnitz). On the Corsican coast is the oyster called foliate
(_O. lamellosa_, Brocchi).

There are two principal varieties of the common oyster dredged on the
French coast, which differ in size and delicacy of flavour. These are
the Cancale and Ostend oyster. When the first has been fed for some time
in the oyster park, and has assumed its greenish hue, it is designated
the Marenna oyster, from "the park" so named in the Bay of Seudre. Of
this green colour we shall speak elsewhere.

Who believed Uncle Jack when he told us in our youth of oysters growing
on trees, and oysters so large that they required to be carved like a
round of beef--of oysters on the Coromandel coast as large as
soup-plates? Nevertheless Uncle Jack's stories were true: there are
oysters which require carving, and oysters have been plucked off trees.
In some parts of America they grow very large. Virginia possesses nearly
two million acres of oyster-beds. The sea-board of Georgia is famed for
its immense supplies; the whole coast of Long Island, extending to a
hundred and fifteen miles, is occupied with them, and all over the
States evidence is to be seen of the estimate in which the favoured
bivalve is held by the American people.

Natural oyster-beds are found in bays, estuaries, and other sheltered
sinuosities of the coast, with shelving and not too rocky bottoms, such
places being, according to the natural law of production, favourable for
the increase of the colony. Such banks abound in every sea. In France
the oyster-beds of Rochelle, of Rochefort, the Isles of Ré and Oleron,
the Bay of St. Brieuc, of Cancale, and Granville, are famous for the
quality of their produce.

On the Danish coast there are from forty to fifty oyster-banks, situated
on the west coast of Schleswig; the best bed lying between the small
isles of Sylt, Amron, Fohr, Pelworm, and Nordstrand. At the point of
Jutland, and opposite Shagen, beds less productive are found.

The great oyster-beds of England extend from Gravesend, in the estuary
of the Thames and Medway, along the Kentish coast on the one hand, and
the estuary of the Colne and other rivers on the Essex coast. The Frith
of Forth is also famous for its oyster-beds, extending from Preston
Pans far up the estuary of the river; but, curiously enough, all these
great banks, without exception, have been impoverished, and all but
exhausted, by improvident dredging, in spite of the "close season" which
has always existed.[10]

       *       *       *       *       *

"He was a bold man who first ate an oyster," has been said before. The
name of the courageous individual has not been recorded, but Mr.
Bertram, in his "Harvest of the Sea," tells us a legend concerning him:
"Once upon a time,"--it must have been a long time ago,--"a man of
melancholy mood was walking by the shores of a picturesque estuary,
listening to the monotonous murmur of the sad sea-waves, when he espied
a very old and ugly oyster-shell all coated over with parasites and
sea-weeds. It was so unprepossessing that he kicked it with his foot,
and the animal, astonished at receiving such rude treatment on its own
domain, gaped wide with indignation, preparatory to closing its bivalve
still more tightly. Seeing the beautiful cream-coloured layers that
shone within the shelly covering, and fancying that the interior of the
shell itself must be beautiful, he lifted up the aged 'native' for
further examination, inserting his finger and thumb within the valves.
The irate mollusc, thinking, no doubt, that this was meant as a further
insult, snapped its pearly door down upon his finger, causing him
considerable pain. After releasing his wounded digit, our inquisitive
gentleman very naturally put it in his mouth. 'Delightful!' exclaimed
he, opening wide his eyes; 'what is this?' and again he sucked his
finger. Then the great truth flashed upon him that he had found out a
new delight--had, in fact, achieved the most important discovery ever
made. He proceeded at once to realize the thought. With a stone he
opened the oyster's stronghold, and gingerly tried a piece of the
mollusc itself. 'Delicious!' he exclaimed; and there and then, with no
other condiment than its own juice, with no accompaniment of foaming
brown stout or pale Chablis to wash it down, no newly-cut, well-buttered
brown bread, did that solitary anonymous man inaugurate the first oyster
banquet."

Another story makes the act of eating the first oyster a punishment. The
poetaster also had his views on the subject:

    "The man had sure a palate covered o'er
    With brass, or steel, that on the rocky shore
    First broke the oozy oyster's pearly coat,
    And risked the living morsel down his throat."

And ever since men have gone on eating oysters. Emperors and poets,
princes and priests, pontiffs and statesmen, orators and painters, have
feasted on the favoured bivalve.

Man has made use of the oyster from the most remote antiquity. Among the
débris of festivals which precede by ages the epoch of written history,
oyster-shells are found. On the "midden heaps" of northern Europe they
are often discovered, mingling with other rubbish and with stone
implements, evidently the refuse of very ancient feasts. We have all
read of the classic feasts of the Romans, which began with oysters
brought from fabulous distances. Vitellius ate oysters all day long, and
the idea prevailed that he could eat a thousand. Calisthenes, the
philosopher, was a passionate oyster eater; so was Caligula; Seneca the
wise could eat his hundred, and the great Cicero did not despise the
savoury bivalve. Lucullus had sea-water brought to his villa from the
shores of the Campania, in which he bred them in great abundance for the
use of his guests. To another Roman, Sergius Orata, we owe the original
idea of the oyster-park. He invented the oyster-pond, in which he bred
oysters, not for his own table, but for profit.

Among modern celebrities whose love of oysters is recorded, we may
mention Louis XI., who feasted the learned doctors of the Sorbonne once
a year on oysters. Another Louis invested his cook with an order of
nobility, in reward for his skill in cooking them. Cervantes loved
oysters, although he satirized oyster dealers. Marshal Turgot used to
eat a hundred or two just to whet his appetite. Rousseau, Helvetius,
Diderot, the Abbé Raynal, and Voltaire, are recorded lovers of oysters.
Danton, Robespierre, and other of the revolutionists, frequented the
oyster _salons_ of Paris. Cambaceres was famous for his oyster feasts,
and it is recorded of the great Napoleon that he always partook of the
bivalve on the eve of his great battles, when they could be procured.

In short, it has been demonstrated as a gastronomic truth that there is
no feast worthy of a connoisseur where oysters do not come to the front.
It is their office to open the way by that gentle excitement which
prepares the stomach for its sublime function, digestion; in a word, the
oyster is the key of that paradise called appetite. "There is no
alimentary substance, not even excepting bread, which does not produce
indigestion under given circumstances," says Reveille-Parise, "but
oysters never." This is an homage which is due to them: "We may eat them
to-day, to-morrow, eat them always, and in profusion, without fear of
indigestion." Dr. Gastaldi could swallow, we are assured, his forty
dozen with impunity--quite a bank must he have eaten. He was
unfortunately struck with apoplexy at table before a _paté de foie
gras_.

Montaigne quaintly says, to be subject to colic, or deny oneself
oysters, presents two evils to choose from, since one must choose
between the two, and hazard something for his pleasure.

England has always been famous for its oysters, and its pearls are said
to have been the chief incentive to Cæsar's invasion. It is not,
therefore, to be supposed that British magnates could be indifferent to
the "native." But the bivalve has perhaps been more celebrated, in prose
and verse, north of the Tweed than south, where silent enjoyment is more
relished than noisy demonstration. Dugald Stewart, Hume, Cullen, and
other Scotch philosophers of the last centuries, had their "oyster
ploys" as an accompaniment to their "high jinks," in the quaint and
dingy taverns of the old town of Edinburgh; and what the bivalve has
been to modern celebrities let the _Noctes Ambrosianæ_ tell.

The oyster may thus be said to be the palm and glory of the table. It is
considered the very perfection of digestive aliment. From Stockholm to
Naples, from London to St. Petersburg, it is always in request. At St.
Petersburg they cost a paper rouble (nearly one shilling), and at
Stockholm fivepence each. For the last year or two the English
amphitryon must pay from two shillings to half a crown a dozen for
choice natives.

For his daily nourishment a man of middle size requires a quantity of
food equal to twelve ounces of dry nitrogenized substance. According to
this calculation, it would be necessary to swallow sixteen dozen of
oysters to make up the necessary quantity. The small proportion of
nutritive matter explains the extreme digestibility of the oyster. It
also explains the immense consumption of them attributed to the Emperor
Vitellius. The oyster is nothing more than water slightly gelatinized.
Without this Vitellius, all emperor and master of the world as he was,
never could have absorbed twelve hundred oysters by way of whetting his
appetite.

The gourmets were long of opinion that the quadrangular pad or cushion
in the bivalve was the most savoury and exciting part. Certain
distinguished amateur performers adopted and proclaimed the principle of
dividing transversely the body of the mollusc, and eating the cushion
only. Natural history explains this gastronomical discovery. It
recognizes the fact that the bile secreted by the liver is contained in
this substance, that it accelerates while it exhausts the qualitative
surface of the tongue and palate, aiding also the functions of the
stomach.

       *       *       *       *       *

We have described the organization of the oyster, and we have said
something of the enjoyment it confers. Did it ever occur to the various
Societies for the Prevention of Cruelty to Animals to consider whether
the oyster might not be a very proper object of their care? Let us see
if we can bridge over the gulf.

We commence operations upon them by dragging them violently from their
own element. We place them out afterwards in water-parks, more or less
briny and unsuitable, filled with villainous green matter, which
presently pervades their breathing apparatus, impregnating, obstructing,
and colouring it; the oyster swells, fattens, and soon attains that
state of obesity which verges on sickness.

When the poor creature has attained its livid green colour, it is fished
up a second time. Alas! it is now doomed neither to return to the sea,
to the park, nor to its native rock. It has water at its disposal only
in the very small quantity which it can retain between its two valves, a
quantity scarcely sufficient to keep away asphyxia. It is shut up in an
obscure narrow basket--an ignoble prison-house, without door or window.
It seems to be forgotten that they are animals: they are piled upon the
pavement like inert merchandise. The basket is carried by railway; the
animal, shaken out of existence almost, is at last landed at the door of
some oyster-shop; and this is the critical moment for the poor bivalve!
It is thrown into a tub with clean water enough to remind it of its
former luxurious life, when it is again seized by the pitiless master of
its fate. With a great knife he brutally opens the shell, cuts through
the muscle by which it adheres to the valve, and violently detaches it,
after breaking the hinges. It is now laid out on a plate, exposed to
every current of air, and in this state of suffering it is carried to
the table. There the pitiless gourmet powders it over with the most
pungent pepper, squeezes over the wounded and still bleeding body the
abomination of its race in the shape of citric acid or vinegar, and
then, alas! with a silver knife which cannot cut, he wounds and bruises
it a second time; or, worse still, he saws and tears and rends it from
its remaining shell; he seizes it with a three-pronged fork, which is
driven through liver and stomach, and throws it into his mouth, where
the teeth cut, crush, and grind it, and, while still living and
palpitating, reduced to an inanimate mass, these organs first triturate
it, while our gourmet is drinking its blood, its fat, and its bile.

We have said that oysters have no head, no arms--that they are without
eyes (although that is disputed), without ears, and without nose; that
they do not stir--that they never cry!

Agreed, perfectly agreed; but all these negatives do not prevent its
being sensible to pain. Two eminent Germans, Herren Brandt and
Ratzeburg, have proved that they possess a well-developed nervous
system, and if they possess sensation they must suffer. "Can an animal
with nerves be impassible?" asks Voltaire. "Can we suppose any such
impossible contradiction in Nature?"

There is consolation, however, for all concerned. Let the humanitarian
fishermen, oyster-dredgers, merchants, and consumers, console themselves
with the vast difference between the helpless imperfect mollusc and the
higher classes of animals. In the case of the former we swallow the
animal, scarcely thinking of its animal nature. It is the denizen of
another element, lives in a medium in which we cannot exist, presents
itself in a form, so to speak, degraded--an obscure vitality, motions
undecided, and habits scarcely discernible. We may therefore see the
oyster mutilated, mutilate them oneself, grind them, and swallow them,
without emotion or remorse.

A learned naturalist dwelling on the sea-shore possessed himself one day
of a dozen oysters. He wished to study their organization; he turned
them, and turned them again, examined their several parts inside and
out. He made drawings of and described them, and, having satisfied
himself that he had exhausted Science in observing, he swallowed them;
the interesting bivalves had lost nothing of their excellence, and the
examination did not prejudice the consummation.

       *       *       *       *       *

Oyster fishing is pursued in a very different manner in different
countries. Round Minorca, divers, with hammers attached to the right
hand, descend to the depth of a dozen fathoms, and bring up in their
left hand as many of the bivalves as they can carry, two fishermen,
usually associating for the purpose, diving alternately until the boat
is filled. On the English and French coasts the dredge is employed, as
represented in PL. XII. This operation is necessary to keep down
vegetation, which would stifle the oysters; the engine is of iron, and
is very heavy. It is thrown overboard, and descends to the bottom of the
sea, which it ploughs and scrapes up, detaching the oysters, and
throwing them into a net attached to the dredge. In this process
oysters, large and small, are torn from their native bed, some going
into the net, but a larger number, old and young, are torn from their
native bed, and buried in the mud. It would be difficult to imagine a
more destructive process; and when the habits of the oyster are
considered, it is evidently one admirably contrived to destroy the race.

In France oyster dredging is conducted by fleets of thirty or forty
boats, each carrying four or five men. At a fixed hour, and under the
surveillance of a coastguard in a pinnace bearing the national flag, the
flotilla commences the fishing. In the estuary of the Thames the
practice is much the same, although no official surveillance is
observed. Each bark is provided with four or five dredges, resembling in
shape a common clasp purse. It is formed of network, with a strong iron
frame, as represented in Fig. 172, the iron frame serving the double
purpose of acting as a sucker, and keeping the mouth open, while giving
it a proper pressure as it travels over the oyster-beds. When the boat
is over the oyster scarp, the dredge is let down, and no more attractive
sight exists than that presented by the well-appointed Whitstable boats
on one side of the estuary, or the Colne boats on the other, as they
wear and tack over the oyster-beds, bearing up from time to time to haul
in the dredge, and empty its contents into the hold. The tension of the
rope is the signal for hauling in, and very heterogeneous are the
contents--sea-weeds, star-fishes, lobsters, crabs, actinia, and stones.
In this manner the common oyster fields on both sides of the Channel
were ploughed up by the oyster dredger pretty much as the ploughman on
shore turns up a field. The consequence was that, twenty years ago, the
French beds were totally exhausted, and France had to look to foreign
countries for its oyster. Oyster farms which had employed fourteen
hundred men and two hundred boats were reduced to two hundred men and
twenty boats. Similar results from over-dredging would have followed, no
doubt, on this side the Channel had the mollusc not been protected by
the company and private proprietors who held the oyster-beds in the
large estuaries. This state of things in France led to some important
discoveries in the science of oyster culture, which have produced
important changes there.

[Illustration: Plate XII.--Dredging for Oysters.]

[Illustration: Fig. 172. Dredge employed in Oyster fisheries.]

The name of Sergius Orata has already been mentioned as a cultivator of
oysters. He lived in the fifth century before our era, and according to
Pliny he first attempted parking oysters at Baia in the times of the
orator Lucius Crassus. He was the first to recognise the superior
flavour of the oysters of the Lucrin Lake, the Avernus of the poets,
probably for trade reasons of his own, for then, as now, Reveille-Parise
remarks, writing on the subject, "tradesmen speculated on the weaknesses
of human gourmandism." But Sergius really created a new industry, which
is still practised in thousands of places much as he left it. As a proof
of the perfection to which Sergius had brought oyster culture, his
contemporaries said of him, in allusion to the hanging banks which he
invented, that if he had been prevented from raising oysters in the
Lucrin Lake, "he would have made them grow on the house-tops." The
traveller who visits this celebrated lake finds only a miry puddle. The
precious oysters placed there by Catiline's grandfather are replaced by
a host of miserable eels, which leap in the mud; vile mountains of
ashes, coal, and pumice-stone, which was thrown up in a night like the
mushroom, having reduced the once celebrated lake into the state
described.

Rondeletius also speaks of a fisherman who understood the art of oyster
culture.

The Neapolitan Lake Fusaro--the terrible Acheron of the poets--is a
great oyster-park, in which Art is made effectually to aid Nature in the
multiplication of its products. This famous oyster-bank, which is
represented in PL. XIII., lies in the neighbourhood of Baia and Cumæ. It
forms one of the most interesting spots in that beautiful bay. In the
month of February, 1865, M. Figuier tells us he traversed its celebrated
coast, seated himself on the banks of the historical lake, and tasted
the produce of this curious manufacture of living beings, whose origin
dates from the Roman period.

Lake Fusaro was in ancient times a place of evil report: Virgil
immortalized it as the mythological Acheron; but its landscape had
nothing of the sadness and desolation which accords with the sojourn of
the dead. It is a salt pond, shaded with a girdle of magnificent trees.
It is about a league in circumference, and about a fathom in depth at
its deepest part; its bottom is muddy and black, like the rest of this
volcanic region.

It will be understood, from what has been said, that the chief obstacle
to the reproduction of oysters is the absence of any solid body to which
the young spawn can attach itself, and the means of shelter from animals
which prey upon them. The fishermen living on the shores of Lake Fusaro
have long realized this, and provided against it by warehousing, as it
were, in the lake near the sea, the oysters ready to discharge their
spawn, while retaining the young generations captive in the protected
basins, where they are sheltered from various causes of destruction to
which oysters are exposed in the open sea.

[Illustration: Plate XIII.--General View of the Oyster Parks on Lake
Fusaro.]

Upon the bottom of the lake, and on its circumference, the
proprietors of Fusaro have constructed hillocks here and there, with
stones heaped up, artificial rocks, raised sufficiently to shelter the
depôts from mud and slime. Upon these rocks they deposit the young
oysters gathered in the Gulf of Tarentum. Each of these rock-works is
surrounded by a girdle of piles, driven close to each other, and raised
a little above the surface of the water, as represented in Fig. 173.
Other piles are distributed in long lines, and bound to each other by a
cord, from which are suspended fagots of young wood. In the spawning
season the oysters which have been deposited on the artificial rocks
discharge the myriads of young fry which have been nurtured in the folds
of their mantles. The fagots suspended from the piles arrest the germ
before it is driven away by the waves, much as a swan attaches itself to
the first shrub which comes in the way. By these precautions the
riverains of Fusaro have provided for the preservation of the young fry,
besides removing many of the natural enemies of the young oyster.

[Illustration: Fig. 173. Artificial Oyster-bank in Lake Fusaro.]

In other places the piles are distributed in long lines and bound
together by strong cords, from which fagots of brushwood are suspended,
on which the young spawn lay hold, as in Fig. 174.

By means of these arrangements the pregnant oyster deposits its spawny
progeny in quiet repose; the young germs are intercepted by the fagots
and hurdles suspended between the piles, where the young oysters
develop themselves under the favourable conditions of repose,
temperature, and light. When the fishing season arrives, the piles and
fagots which surround the beds are removed, and the oysters are gathered
suitable for market. The oysters thus selected for sale are packed
loosely in osier baskets and sunk, while waiting for purchasers, into a
reserve or park. This park is established on the shores of the lake. It
is constructed of piles which support a gangway provided with hooks,
from which the baskets filled with living oysters are suspended, ready
for sale.

[Illustration: Fig. 174. Pillars with cords attached in Lake Fusaro.]

Some twenty years ago the oyster-beds of France had become totally
exhausted under the open system of dredging; and circumstances having
brought the protective system pursued at Fusaro under the notice of M.
Coste, a learned academician, to whom France is indebted for the
restoration of the bivalve, M. Coste reported to the Emperor in 1858
that at Rochelle, Marennes, Rochefort, at the Isles of Ré and Oleron,
where there had formerly been twenty-three oyster-beds, there were now
only five, and these in danger of being destroyed by the increase of
mussels; that at the Bay of St. Brieuc, so naturally suited for oyster
culture, the beds were reduced to three; that even on the classic oyster
grounds of Cancale and Granville, it was only by the most careful
administration that decay was prevented, while the increasing numbers of
consumers threatened altogether to destroy an industry essentially
necessary for the support of a maritime population.

The impulse given by this report has been productive of the most
satisfactory results in France. All along the coast the maritime
populations are actively engaged in oyster culture. Oyster parks, in
imitation of those at Fusaro, have sprung up. In his appeal to the
Emperor, M. Coste suggested that the State, through the Administration
of Marine, and by means of the vessels at its command, should take steps
for sowing the whole French coast in such a manner as to re-establish
the oyster-banks now in ruins, extend those which were prosperous, and
create others anew wherever the nature of the bottom would permit. The
first serious attempt to carry out the views of the distinguished
academician was made in the Bay of St. Brieuc. In the month of April in
the same year in which his report was received, operations commenced by
planting three millions of mother-oysters which had been dredged in the
common ground; brood from the oyster grounds of Cancale and Tréquiers
were distributed in ten longitudinal lines on tiles, fragments of
pottery, and valves of shells. At the end of eight months the progress
of the beds was tested, and the dredge in a few minutes brought up two
thousand oysters fit for the table, while two fascines drawn up at
random contained nearly twenty thousand, from one to two inches in
diameter. Two of these fascines exposed to public view at Béni and
Patrieux excited the astonishment of the maritime population.

This result encouraged M. Coste to pursue his experiments upon a greater
scale, and he now proposed to bring the whole littoral under a regulated
system of oyster culture. In the roads of Toulon and in Lake Thau, which
touches this port, the same system was put in force by the
Administration of Marine as had already been done in the Bay of Arcachon
and in the Isle of Ré. In these localities oyster culture assumed
gigantic proportions. Associations were formed for the purpose of
prosecuting them and forming oyster-parks.

These exertions roused the curiosity of foreign nations. Van Beneden, a
distinguished naturalist of Louvain, and M. Eschrecht of Copenhagen,
visited France to study the arrangements for oyster culture. M. Coste
demonstrated that parks could be established on all places visited by
the tide, and under his advice the Bay of Arcachon is now transformed
into a vast field of production, which increases every day, giving the
happiest presages of an abundant harvest. Already twelve hundred
capitalists, associated with a similar number of fishermen, occupy a
surface of nine hundred and eighty-eight acres, which emerge at low
water. In this bay the State has organized two model farms for
experimental purposes, in which tiles, fascines, and valves of shells
are laid down with other appliances, to which the young oysters may
attach themselves. These expedients have been so successful that the
park, which has cost about £114, is now estimated to be worth about
£8000 in money, with a total of five million oysters, large and small.
The Isle of Ré, which was originally surrounded by a muddy bottom ill
adapted for oyster culture, has been totally changed, so that in two
years four leagues of foreshore have been turned into a rich and
profitable oyster-bed; twelve hundred parks are in full activity, and
two thousand others are in course of construction, the whole forming a
complete girdle round the island.

Every one has heard of the green oysters of Marennes, the preservation,
amelioration, and ripening of these oysters, so to speak, representing a
very considerable branch of industry in France. In order to give the
reader some idea of its importance, we shall give here a brief summary
of M. Coste's voyage of exploration on the French littoral.

The parks at Marennes, in which the oysters are placed in order to
acquire the green colour which characterises them, are basins stretching
along both banks of the Seudre for many leagues. They are locally known
as _claires_, and differ from the oyster-parks of other countries in
this particular--that, while the ordinary parks are so arranged as to be
submerged at every return of the tide, the basins of Marennes are so
arranged that they can only be submerged at spring tides; that is, at
the new and full moon, when the waters rise beyond the ordinary level.

The basins of _claires_ occupy from two hundred and fifty to three
hundred square yards of superficies; two sluices permit of the entrance
and withdrawal of water at will, so as to maintain it at the level most
convenient to the industrial wants of the place, or to empty it
altogether when it is necessary to cleanse the basin, pave the bottom,
and furnish it with a fresh supply of oysters.

When these necessary works are completed, advantage is taken of the
first spring tide to fill the basin. When the tide begins to ebb, the
sluices are closed, so as to retain sufficient water in the basins; and
while thus shut up, salt held in solution is deposited, and qualities
analogous to those of marine bottoms are produced, purged by cleansing
processes of all products offensive to the bivalves.

When the basin has been filled with sea-water for the necessary time,
and the bottom is sufficiently impregnated, it is emptied and left to
dry; and now, the soil being prepared, it only remains to furnish it
with oysters of a mellow and ripe age, in order to give them their green
hue. Towards the month of September, at low water, the whole sea-side
population of Marennes go to gather oysters on the pavement left
uncovered by the ebbing tide, or by using a dredger in the deeper parts
of the _claires_ where the water still remains. A temporary magazine for
the reception of the oysters thus gathered is erected on the banks,
which the water revisits twice a day. The young are reserved for
cultivation on the parks or _claires_; the fullest are sold for
consumption in the neighbourhood; but the quantity of oysters raised at
Marennes is insufficient to supply the demand. About a third of the
provision intended for the _claires_ comes from the coasts of Brittany,
of Normandy, and La Vendée. "These foreign oysters," says M. Coste,
"never attain the fine flavour of those bred in the locality. It is
necessary to keep them for a long time in the _claires_ before they are
sufficiently ameliorated, and, even when they become green, they retain
traces of their primitive nature, remaining hard, in spite of the new
qualities imparted to them by cultivation; a certain bitterness remains,
which is easily distinguished by the true amateur; it is the same with
indigenous adult oysters. When they are taken at this stage of their
existence the colouring does not succeed with them;--it is only, so to
speak, the false brand used to give a speculative value to the
merchandise. It is not enough that the mollusc should have a fine
flavour; it must have the peculiar taste. It is not enough that it has
the green hue; it is necessary that these qualities should pervade it
from the earliest age, and that the culture of the _claires_ should
continue to the end." It is thus necessary that the oysters for the
_claires_ of Marennes should be selected when from twelve to eighteen
months old, that the shells should be well-formed, and free from all
foreign bodies adhering to the surface. Being thus carefully picked out,
the oysters are distributed over the bottom of the _claires_ with a
shovel, and afterwards so arranged by the hand that they may not touch
each other when they increase in size; that they do not embarrass each
other by the movements of their valves; and that nothing should
interfere with the regularity of their forms. The young colony reposes
under a sheet of water from twelve to eighteen inches deep, which is, as
we have said, only renewed at spring tides, which reach the level. Nor
are the oysters abandoned to themselves in these privileged beds while
they are growing and ripening. They are objects of continual care and of
special manipulation. The spring tides visit the _claires_ charged with
mud, which, if deposited in the motionless basins, would act as a mortal
poison to the young mollusc; hence the necessity of transporting them
from one _claire_ charged with mud into others free from such
accumulations; and this is a process in constant operation until the
animals are finally gathered for consumption. Oysters deposited in the
_claires_ aged eighteen months should remain two years before they are
ready for use; but three and even four years are required to give them
the full degree of perfection which characterises the best products of
the Marennes oyster-parks.

Oysters placed in the reservoirs in an adult state become green, it is
true, in a very few days, but they never attain the exquisite flavour of
those which have been bred in the parks, and have undergone the costly
manipulation described from their earliest years.

The question arises, What is the colouring principle which is here in
operation? The green colour is not general; it is shown principally on
the branchiæ, upon the labial feelers and intestinal canal; it is rather
undecided; and the colouring matter appears to differ chemically from
all other known pigments of green colour. Must it be attributed to the
soil of the _claire_? This is its most probable origin. But many
naturalists insist that the colouring matter proceeds from an infusorial
animalcule, the green-coloured Vibrion. Others have hazarded the opinion
that it is a disease of the liver in our unfortunate bivalve which
produces the colour. Bile secreted in excess by a diseased liver would
give a green hue to the parenchyma of the respiratory organs of an
animal rendered sick by the exceptional treatment to which it has been
subjected. Of these three opinions, says M. Figuier, the first, as we
have said, presents the greatest appearance of probability.

       *       *       *       *       *

The system of oyster farms, which has worked admirably for the
companies themselves, has proved of doubtful utility, so far as the
oyster-eating public is concerned, as the following sketch of the
Whitstable oyster farms will show. The oyster farm at Whitstable is
co-operative in the best sense of the term, and has been in operation
for many years. The Company possesses large oyster grounds, and a fine
fleet of boats kept for the purpose of dredging and planting the beds;
it is established under the Joint Stock Companies Act, but there is no
other way of entrance into it but by birth, as none of the free
dredgermen of the town can hold shares. "When a man dies his interest in
the Company dies with him, but his widow, if he leaves one, obtains a
pension. The affairs of the Company are managed by twelve directors, who
are called "the jury."

"The layings at Whitstable," to summarise Mr. Bertram, "occupy about a
mile and a half square; and the oyster-beds have been so prosperous as
to have obtained the name of the 'happy fishing grounds.' Whitstable
lies in a sandy bay, formed by a small branch of the Medway, which
separates the Isle of Sheppey from the mainland. Throughout this bay,
from the town of Whitstable at its eastern extremity to the old town of
Faversham, which lies several miles inland, the whole of the estuary is
occupied by oyster farms, on which the maritime population, to the
extent of three thousand people and upwards, is occupied; the sum paid
for labour by the various companies being set down at £160,000 per
annum, besides the employment given at Whitstable in building and
repairing boats, dredges and other requisites for the oyster-fishing.
The business of the various companies is to feed oysters for the London
and other markets, to protect the spawn or floatsome, as the dredgers
call it, which is emitted on their own beds, and to furnish, by purchase
or otherwise, the new brood necessary to supply the beds which have been
taken up for consumption."

We have hinted above that in oyster, as in other fisheries, a wasteful
spirit of extravagance has hitherto prevailed. It appears, however, that
no rule can be laid down even as to the particular year in which the
oysters will spawn, much less where it will be carried to; for, although
the artificial contrivances adopted by Sergius Orata for saving the
spawn are perfectly well known to the parties interested here, they have
not hitherto been imitated; the practice of the companies and private
owners of oyster-layers being to purchase their young brood from the
dredgers and others who fish along the public foreshore and open grounds
on the Kent and Essex coasts, and even as far north as the Frith of
Forth. The little bay of Pont, for instance, on the Essex coast, which
is an open piece of water sixteen miles long and three broad, free to
all, and which formerly yielded considerable supplies to Billingsgate,
now gives employment to a hundred and fifty boats, each with crews of
three or four men, who are wholly employed in obtaining young
brood--that is, oysters from eighteen months to two years old, which
they sell to the oyster farmers. The result is, that the oyster farms
have become a vast monopoly. By tacit consent they agree to feed the
market at some eight pounds sterling per bushel; they pay the dredger
one-fourth of that sum; and as the common fishing grounds are thus
rendered mere nurseries of young brood, the lover of the bivalve must
reconcile himself to pay a monopoly price for the precious morsel.

The system pursued at Whitstable, and other oyster-parks in the estuary
of the Thames and Medway, is most efficient. The oysters reared in them,
called "natives," in contradistinction to those called "commons," which
are bred in their natural beds, are justly considered to be very
superior in flavour, although they are a mixed breed, being brought from
every quarter to augment the stock.

The Thames, or "native" system, is as follows: Every year each layer is
gone over and examined by means of a dredge, successive portions being
done day by day, till it may be said that each individual oyster has
been examined; the young brood is detached from its bed, the double
oysters are separated, and all kinds of enemies killed. During three
days in each week dredging is pursued for "planting;" that is, for
transference from one bed to another more suitable for their growth or
fattening, and for the removal of the dead or sickly oysters and
mussels. On the other three days dredging for market takes place, when
the more mature beds are dredged, and as many are lifted as are
required. Not only is this constant dredging of the beds themselves
necessary, but the public beds immediately outside require the same care
to keep them in a fit state, and free from enemies.

The same story of over-fishing and improvidence extends round our whole
coast. The far-famed Pandores obtained at Preston Pans, near Edinburgh,
once so cheap, are becoming scarce and dear. The brood is caught and
barreled for export to Holland and other places, especially the Thames
oyster farms. English buyers pick the grown oysters for Manchester and
other large provincial markets, and the Corporation of Edinburgh, the
Duke of Buccleuch, and other proprietors of the foreshore, have just
interfered in time to prevent the total destruction of the trade, when
the wild song of the Cockenzie dredgerman might have been left to charm
some future antiquary, as it is now said to charm the oyster into the
dredge with its refrain:

    "The herring it loves the merry moonlight,
      The mackerel it loves the wind;
    But the oyster it loves the dredger's song,
      For it comes of a gentle kind."

The Scallop-shell (_Pecten_) is round, nearly equal-sided, resting on
the right valve, which is more convex and marked with radiating ribs.
Linnæus made the mistake of confounding with the _Ostrea_ a great number
of shells, which, by their channeled edges and surfaces, strongly
reminded one of the arrangements of the teeth of a comb, whence their
name of _Pecten_. They were well known to naturalists long before the
time of Linnæus, under the name of _Pilgrims'_ shells, a name which came
into use from the practice which prevailed among pilgrims in the middle
ages--we know not why--of ornamenting habits and hats with the valves of
some of the species.

The shell of the _Pecten_ is in general nearly circular, more or less
elongated, and terminated towards the summit in a straight line, forming
a sort of triangular appendage called the ear, to which the hinges are
attached. The valves are very regular, but with no resemblance to each
other. In some species, the shell of which is closely shut, the lower
valve is more or less convex than the upper one. In others, both valves
are convex. The hinge is without teeth, and the ligament, which is
intended to close the shell, is inserted into a triangular depression or
dimple. The retractile muscle is unequal, and nearly central. The valves
are not nacred inside, and are formed on their exterior surface of
numerous fluted channels, which spring from a lobe more or less pointed
at the summit, diverging towards the circumference. The edges are
sometimes smooth, as in the Watered Pecten (_P. pseudamussium_, Fig.
175), but more frequently they are formed in strips or scales, as in the
Smooth-shelled Pecten (_P. glaber_, Fig. 176). Upon the whole, however,
the Pectens are very variable, but always elegant in form; the colours
are frequently lively and brilliant. In PL. XIV., some of the most
striking forms are represented, as in Fig. I., the Ducal Mantle (_Pecten
pallium_), an inhabitant of the Indian Ocean, remarkable for its elegant
form, its twelve radiating stripes, diverging towards the circumference,
the horizontal furrows of its salient scales, and the striking
distribution of its white spots upon a bed of red and brown marble; Fig.
II., the Purple Pecten; Fig. III., the Coral Pecten; Fig. IV., the Tiger
Pecten; Fig. V., the Foliaceous Pecten; and Fig. VI., the Northern
Pecten.

[Illustration: Fig. 175. Pecten pseudamussium (Chenu).]

[Illustration: Fig. 176. Pecten glaber (Linnæus).]

The animal which inhabits the Pecten shell has the general form of the
oyster, differing however from it in a remarkable manner. The edges of
the mantle are furnished with multiplied fringes of simple tentacles,
between which we find other tentacular appendages a little thicker, each
terminating in a sort of small pearl, vividly coloured, to which is
attached a nervous thread, which has been taken for an eye. Another
difference: the branchiæ, in place of being connected by a striated
lamina, as is the case in the oyster, are cut into parallel capillary
filaments, forming a free and floating fringe, and the mouth is
surrounded by salient many-cleft lips.

[Illustration: PLATE XIV.--Pectinidæ.

    I. Pecten pallium. (Linn.)
    II. Pecten purpuratus. (Lamarck.)
    III. Pecten foliaceus.
    IV. Pecten tigris. (Lamarck.)
    V. Pecten nodasus. (Linn.)
    VI. Pecten islandicus. (Chemnitz.)
]

While the oyster shell is completely fixed to its bed, the Pecten is, on
the contrary, perfectly free, and shifts from place to place, moving in
the water even with a certain amount of agility; by smartly closing its
half-opened valves and forcibly expelling the water, it moves backward
by a sort of reaction; this action, repeated many times, compels the
animal to move almost in spite of itself, and enables it to avoid
danger, or directs its steps towards the spot it wishes to reach.
Some naturalists even assert that, when raised to the surface, the
Pecten half opens its shell in such a manner that the upper valve serves
the purpose of a sail.

[Illustration: Fig. 177. Pecten opercularis (Linnæus).]

The Pectens, of which a hundred and seventy-six species are described,
are inhabitants of every known sea. Twenty species belong to Europe,
among which we may mention _P. opercularis_, represented in Fig. 177;
_P. glaber_, and _P. nivea_. Fig. 178 represents the White-mantled
Pecten (_P. plica_, Linn.) of the Indian Ocean, and Fig. 179, the
Concentric Pecten (_P. Japonica_) of the Japan seas.

[Illustration: Fig. 178. Pecten plica (Linnæus).]

[Illustration: Fig. 179. Pecten Japonica (Gmellin).]

Among the Ostreadæ the shells of _Spondylus_ are distinguished for their
variety of form and the brilliant colours with which they are decorated.
This makes them much sought after by amateur collectors, and procures
for them a high price. The shell of _Spondylus_ is solid and thick, with
unequal adherent valves, nearly always bristling with spines, forming a
very peculiar kind of ornamentation to the valves; the hinges have two
very strong teeth. The animals which inhabit this shell resemble the
oyster in many respects, but they still more closely resemble the
Pectens. The edges of the mantle are provided with two rows of
tentacles, the exterior row being, many of them, furnished at their
extremities with coloured tubercles. As examples, we note several
species of these bivalves for representation. _Spondylus regius_ (PL.
XV. Fig. I.) is, perhaps, the most remarkable for its immense spines.
_Spondylus radians_, Lamarck (Fig. III.), is noted for its elegant form.
_Spondylus avicularis_ (Fig. IV.) shows remarkable inequality in the
valves. _Spondylus imperialis_, Chenu (Fig. II.), has long projecting
spines, like feet, and the Scaly Spondylus (_S. crassisquama_, Fig. V.)
is covered with scales arranged like so many roofing-tiles.

Like oysters, the genus Spondylus is frequently found firmly rooted to
rocks and other submarine bodies, and, oftener still, heaped one upon
the other, like herrings in their barrel.

These animals belong essentially to the seas of warm countries. We find
them, however, occupying considerable space in the Mediterranean, where
(Fig. VI.) the Ass-footed Spondylus (_S. gæderopus_) abounds.

But the most remarkable species of all is assuredly _Spondylus regius_
(PL. XV. Fig. I.). This species is a native of the Indian Ocean, and
there scarcely exist three fragments of this rare shell in the museums
of Europe. M. Chenu relates in one of his books an anecdote which would
prove--if any proof were necessary--how far the desire of a collector to
obtain possession of some rare and costly specimen will carry him in
order to attain his object. "M. R----," says M. Chenu, "was Professor of
Botany to the Faculty of Paris, and was, as some times happens, more
learned than rich; he wished, on the invitation of a stranger, to
purchase one of these shells at a very high price, which might be from
3000 to 6000 francs; the bargain was made, and the price agreed upon; it
was only necessary to pay. The money in the professor's hands made only
a small part of the sum the merchant was to receive for his shell, and
he would not part with it without payment. M. R----, now consulting his
desire to possess the shell more than his weak resources, made up
secretly a parcel of his scanty plate, and went out to sell it. Without
consulting his wife he replaced his silver plate by coverings of tin,
and ran to the merchant to secure his coveted Spondylus, which he
believed to be _S. regius_.

[Illustration: PLATE XV.--Spondylus.

    I. Spondylus regius. (Linn.)
    II. Spondylus imperialis. (Chemu.)
    III. Spondylus radians. (Lamarck.)
    IV. Spondylus avicularis. (Lamarck.)
    V. Spondylus crassisquama. (Lamarck.)
    VI. Spondylus gæderopus. (Linn.)
]

"The hour of dinner arrived, and we may imagine the astonishment of
Madame R----, who could not comprehend the strange metamorphosis of her
plate. She delivered herself of a thousand painful conjectures on the
subject. M. R----, on his part, returned home happy with his shell,
which he had committed to the safe custody of a box placed in his coat
pocket. But, as he approached the house, he paused, and began for the
first time to think of the reception he might meet with. The reproaches
which awaited him, however, were compensated when he thought of the
treasure he carried home. Finally, he reached home, and Madame R----'s
wrath was worthy of the occasion; the poor man was overwhelmed with the
grief he had caused his wife; his courage altogether forsook him. He
forgot his shell, and, in his trepidation, seated himself on a chair
without the necessary adjustment of his garment. He was only reminded of
his treasure by hearing the crushing sound of the broken box which
contained it. Fortunately, the evil was not very great--two spines only
of the shell were broken; but the good man's grief made so great an
impression on Madame R----, that she no longer thought of her own loss,
but directed all her efforts to console the simple-minded philosopher."

The variation in the number and direction of the spines is a striking
feature in Spondylus. When the whole lower surface adheres to branches
of coral, a very frequent occurrence, they are confined to the upper
valve, but when a part only of the valve, the whole surface becomes
covered.

Having finished our short sketch of the Conchifera, we shall now treat
of the singular group, Brachiopoda,[11] which some place nearer to the
Gasteropoda than the Pteropoda, giving them, in fact, their place. It is
out of the province of this work to enter into the physiological
arguments of such a question. The days of the Brachiopoda or
short-footed animals are past. Of the 1842[12] species formerly known, a
few types of a small number of genera only are left, numbering in all
102. The Terebratulidæ are best represented; there were once 300 or 400
species; there are now not more than 67 in the seas of the world. The
difference between the past and the present is especially striking, when
we compare the recent and fossil species of Europe. Among no other class
of shells has there been such a wholesale extinction of species. The
great family of Spiriferæ are wholly extinct, and of 400 Rhynconella
only four are now living. The curious Crania, Discina, and Lingula are
still living, and are mostly found in the seas of the southern
hemisphere.


FOOTNOTES:

[Footnote 9: We give this illustration as representing the comparative
size of the oysters at different ages; but it is necessary to state that
the specimens were artificially attached to the block by means of glue
for exhibition. Oysters always attach themselves by the back of the
rounded shell near to the hinge, as stated at p. 363.]

[Footnote 10: The cause of the present scarcity of oysters is a
much-vexed question. Mr. Frank Buckland, the greatest living authority
on oyster and fish culture, attributes it to sudden changes of
temperature at the critical period when the spat is newly formed, rather
than to over-dredging.--ED.]

[Footnote 11: The _Brachiopoda_ may be thus tabulated:--

Family.

    I. _Lingulidæ_, containing Lingula and other fossil genera.
    II. _Discinidæ_, containing Siphonolreta and Discina.
    III. _Craniadæ_, containing Crania.
    IV. _Productidæ_, containing Chonetes and Productus, fossil.
    V. _Orthidæ_, containing Calceola, Davidsonia, Strophomena, and Orthis.
    VI. _Rhynconellidæ_, containing Atrypa, Pentamerus, and Rhynconella.
    VII. _Spiriferidæ_, containing Uncites, Retzia, Athyris, and Spirifera.
    VIII. _Terebratulidæ_, containing Thecidium, Agriope, Terebratella,
           and Terebratula.
]

[Footnote 12: Woodward's Manual, p. 135.]



CEPHALOUS MOLLUSCA.



CHAPTER XIII.

GASTEROPODA.


We shall now consider the Gasteropoda, which is divided into four
orders. Firstly, Nucleobranchiata, animals which float on the surface of
the ocean: they are Diæcious, or in separate sexes, and the nervous
system is widely distributed in the body, the shell, in Carinaria, for
instance, covering only a very small portion of the body. The first
family of this order is Atlantidæ, of which the types are the fossil
Bellerophon and the recent Atlanta.

The second family is Firolidæ, the types of which are Carinaria and
Firola. Carinaria or glass nautilus is shaped like the bonnet-cap shell,
Pileopsis. It is as transparent as glass; and although now very common,
was formerly one of the most highly-prized shells by collectors. The
second order of Gasteropoda is Opistho-Branchiata, and is divided into
two sections, the Nudibranchiata, and the Tectibranchiata. The
Nudibranchiata have no shell except in the larva state; they mostly live
at the bottom of the sea on rocky shores, but a small number swim on the
surface. They are remarkable for their variety of form and vivid
colouring, being the most beautiful of all molluscous animals; they may
truly be called the caterpillars of the sea, for their branchiæ remind
us of the spines with which many lepidopterous larvæ are covered.

The first family is Elysiadæ, types Limapontia and Elysia.

The second is Phyllirhoidæ, type Phyllirhoe.

The third is Æolidæ, types Glaucus and Æolis.

The fourth is Tritoniadæ, types Scyllæa and Tritonia.

The fifth is Doridæ, types Idalia and Doris, the curious sea-lemon.

The first family of the second division, Tectibranchiata, is
Phyllidiadæ, types Diphyllidia and Phyllidia.

The second family is Pleurobranchidæ, types, Umbrella, in form
resembling a limpet, and Pleurobranchus.

The third family is Aplysiadæ, types, Dolabella and Aplysia.

The fourth family is Bullidæ, types, Scaphander, Acera, and Bulla.

The fifth family is Tornatellidæ, types, Tornatina and Tornatella.

The third order is the Pulmonifera, and the fourth is the
Prosobranchiata; we shall speak of them in the next chapter.

In this family we reach a group of Gasteropods much more numerous, both
in species and in special types, which respire by the aid of branchiæ,
or gills. Cuvier divides them into many orders, based chiefly upon their
respiratory organs.

The Tectibranchiata have the gills attached either to the right side of
the body or upon the back, arranged in the form of leaflets, more or
less divided, but not symmetrical, and nearly covered by the mantle.
_Bulla_ and _Aplysia_ are the two principal genera of the group, and may
be considered as the type of two small families.

The _Aplysiæ_ were known to the ancients under the name of sea-hares
(_Lepus marinus_), from some fancied resemblance to the terrestrial
hare. They were objects of profound horror, inspired either by their
singular form, or from an acrid, caustic, and inodorous liquid which
they secrete. A magic influence was attributed to them; they were
supposed, for instance, to have influence over the female heart. It is
not easy, however, to explain the evil renown acquired by an animal
which is known to be gentle and even timid. They are naked and fat,
somewhat resembling the Limnæa in their oval, elongated form, their
thickness in the dorsal region, and their posterior locomotion. Their
head, which is very indistinct, is furnished with four tentacles, the
anterior two of which are the largest, and somewhat resemble the ears of
a hare. The eyes are found at the base of the posterior tentacles. These
characters are observed in _Aplysia depilans_ (Fig. 180). _Aplysia inca_
shows also the same arrangement (Fig. 181). In this family the mollusc
is much more important from its volume than from its internal,
rudimentary, and horny shell, which is contained in the branchial
shield. In Fig. 182 we have the small and thin cartilaginous shell which
exists in the interior of the animal.

[Illustration: Fig. 180. Aplysia depilans (Lin).]

[Illustration: Fig. 181. Aplysia inca (D'Orbigny).]

[Illustration: Fig. 182. Shell of Aplysia inca.]

The Aplysiæ are found nearly in every region of the globe, not only upon
the shores of the Continent, but on every island shore. They commonly
inhabit sandy and muddy shores of small depths, or even the rocky
recesses, or under shelter of the stones which have fallen from the
cliffs. Their eggs consist of those long filaments which are discharged
in immense numbers, and which fishermen call sea-worms.

They feed upon certain algæ, with which the bottom of the sea is
covered; but they eat, also, small marine animals, such as the naked
molluscs, annelids, and crustaceans.

We are the less astonished to see the Aplysiæ so gluttonous when we
learn how liberally Nature has accorded to them organs of mastication,
trituration, and digestion. Their mouth is formed of thick and muscular
lips; a very long oesophagus or gullet succeeds, and this oesophagus
does not communicate with a single stomach, but with four--one enormous
membranous crop, an exceedingly muscular gizzard, with two accessary
pockets, one of which terminates in the form of a sac. The gizzard has
thick walls, and is furnished on the internal wall with cartilaginous
quadrangular pyramids, the summits of which intertwine. This apparatus
is intended to bruise the food when it reaches the third stomach. It is
also armed with little hooks, the curvature of which is directed towards
the entrance of the gizzard.

The genus _Bulla_ differs materially from the Aplysiæ. They have a
well-developed shell, the form of which is elegant; they are delicate in
structure; their brilliant colours, consisting of red, black, or white
bands, separated by many varied tints, cause these little molluscs to be
much sought after for ornamental collections. The shell itself is oval
or globulous, rolled up in a scroll, smooth, spotted, very thin and
fragile, with a concave spiral, umbilicate, open in all its length, with
a straight, wide, and cutting edge.

[Illustration: Figs. 183 and 184. Bulla ampulla (Linnæus).]

Obtuse at its two extremities, neither the head of the animal nor the
tentacles are very apparent. The gills are placed under the back, a
little to the right and behind; its stomach, which alone fills a great
part of the cavity of the body, presents the peculiarity, already noted
in the Aplysia, of being furnished with bony pieces, evidently intended
to grind the food.

[Illustration: Fig. 185. Bulla oblonga (Adams).]

[Illustration: Fig. 186. Bulla aspersa (Adams).]

[Illustration: Fig. 187. Bulla nebulosa (Gould).]

The Bullæ can swim with facility in deep water, but they evidently
prefer the shallows and a sandy bottom, feeding upon smaller molluscs.
They are found in every sea, but they abound chiefly in the Indian Ocean
and Oceania. Some species, however, such as _Bulla ampulla_ (Figs. 183
and 184), the shell of which is shaded grey and brown, and the
Water-drop (_Bulla hydratis_), inhabit European seas. _Bulla oblonga_
and _Bulla aspersa_ (Adams), and _Bulla nebulosa_ (Gould), represented
in Figs. 185, 186, and 187, are also well-known species.

We take leave of our little friends the Headless Mollusca or _Acephalæ_,
and direct our attention to those molluscs to which Nature has been more
generous, and furnished with a head. This head, however, is still
carried humbly; it is not yet _os sublime dedit_; it is drawn along an
inch or so from the ground, and in no respect resembles the proud and
magnificent organ which crowns and adorns the body of the greater and
more perfectly organized animals.

The organization of the Cephalous Mollusca present three principal
types, which has led to their being divided into three classes, after
their more salient characteristics of form and locomotive apparatus;
namely, _Gasteropoda_, _Pteropoda_, and _Cephalopoda_.

In the class _Gasteropoda_ (from γαστὴρ, _belly_, ποῦϛ,
gen.ποδὸϛ, _foot_) the locomotive apparatus consists of a
flattened muscular disk, placed under the belly of the animal, aided
by which it creeps. The Snail (_Helix_), the Slug (_Limax_), and the
Cowrie, (_Cyprea_), are types of this class.

In the _Pteropoda_, from πτερὸν, _wing_, and ποῦϛ, _foot_, the
locomotive apparatus assumes the form of wings, or membranous
swimming-fins, placed on each side of the neck. The _Hyalea_ and _Clio_
are types of this class.

In the _Cephalopoda_, from κεφαλὴ,, _head_, and ποῦϛ, _foot_,
the locomotive apparatus consists of arms, or tentacles, which surround
the mouth in numbers more or less considerable. The Cuttle-fish
(_Sepia_), and the Poulpes (_Octopoda_) are types of this last class.

The Molluscous Gasteropoda have the organs of respiration formed for
aerial respiration, or for respiration under water.

This physiological arrangement involves important differences in
internal organization in these molluscs, and renders it convenient to
divide them into two secondary groups; namely, _Pulmonary Gasteropods_,
which breathe in the air, and by a species of lung, and _Non-pulmonary
Gasteropods_, which breathe in the water, by means of branchiæ or
gills.



CHAPTER XIV.

PULMONARY GASTEROPODS.


The _Pulmonary Gasteropods_ comprehend those molluscs which, as we have
said, live in the air and breathe the natural atmosphere. The
respiratory organ is a cavity in the walls of which the blood-vessels
form a complicated network. The air enters this cavity through an
orifice, which the animal opens and shuts at will--a species of lung, in
short, which is placed upon the back of the animal. They are both
terrestrial and aquatic animals. In the latter case, they must come to
the surface of the water in order to breathe, like the phocas and
cetacea among the Mammifera.

The Pulmonifera, the second order of Gasteropods, comprehends those
animals which live in and breathe the air.

It is divided into four sections; the Operculata, or animals whose
shells are closed by an operculum, and the In-Operculata, or animals
without operculum.

Operculata is divided into two families; first, Aciculidæ, types,
Geomelania and Acicula; and second, Cyclostomidæ, types, Pupina and
Cyclostoma. Cyclostoma is perhaps the best known; the mouth is circular,
the name being derived from _cyclos_, circle, and _stoma_, mouth.

The second section, In-Opercula, contains five families.

First, Auriculidæ, types, Conovulus and Auricula.

Second, Limnæidæ, types, Planorbis, Physa, and Limnæa.

Third, Oncidiadæ, types, Vaginulus and Oncidium.

Fourth, Limacidæ, types, Testacella and Limax.

Fifth, Helicidæ, types, Clausilia, Pupa, Achatina, Bulimus, Succinea,
Vitrina, and Helix.


LIMNÆIDÆ.

The Limnæidæ, _Aquatic Pulmonary Gasteropods_, is the second family of
the series. They belong to the group that come to the surface of the
water to breathe, as do the cetacea and phocas among the Mammifera. The
_Limnæa_, _Planorbis_, and _Physa_ are the principal members of this
group.

Limnæa lives in great numbers in the stagnant waters of all countries,
particularly of temperate climates. It cannot remain long under water,
being compelled frequently to rise to the surface in order to breathe
atmospheric air. It is even observed, by a mechanism not very well
understood, to turn itself upside down, in such a manner as to present
itself feet uppermost, and to move slowly along in this position,
creeping, as it were, through the water. It is difficult to comprehend
how the movable liquid bed upon which the animal operates can offer
resistance enough to permit of its creeping as if it were on a solid
resisting body; it seems to produce the movement with the assistance of
its foot, which is broad and thick, and shorter than the shell.

[Illustration: Fig. 188. Limnæa stagnalis (Linnæus).]

Limnæa has a large flat head, from each side of which issues a
triangular contractile tentacle, carrying at its base and on the inner
side an extremely small dot, or eye. The most considerable part of the
body, comprehending the visceral mass, is spiral, and is contained in a
thin diaphanous shell (Fig. 188), the turns in the spiral of which are
generally elongated, the last turn being larger than all the others. The
interior of this is occupied by the respiratory cavity, which
communicates outwardly by an opening analogous to that which exists in
the snails. This opening dilates and contracts in such a manner as to
receive the air in the cavity, and exclude water when the animal feeds
itself under the water. The mouth is a transverse slit between two
rather thin lips, and is armed with small canine teeth. When the animal
sallies from its shell, it has the appearance of a short trumpet. In its
interior is a roundish, thick, and fleshy tubercle, not unlike the
tongue of a paroquet. The true tongue, however, which lies at the bottom
of the slit, is flat, oval-shaped, and supported by a cartilaginous or
bony pedicle.

Limnæa, aided by this very complicated buccal apparatus, is enabled to
feed itself with vegetable substances, such as the leaves of aquatic
plants, which it cuts and bruises with its teeth. They are very active
in the season, reproducing towards the end of spring. At this period
little oval or semi-cylindrical masses are frequently found adhering to
floating bodies, glittering and transparent as crystal. These are
agglomerations of the eggs of Limnæa. When winter sets in, the _Limnæa_
of our climate fall into a state of torpor, and sink, more or less
deeply, into the mud of the lakes, marshes, rivers, or brooks, which
they inhabit.

They are of great utility, both to feed fishes and aquatic birds, and
also as scavengers of the decaying vegetation of brooks.

Planorbis has an organization analogous to Limnæa, of which it is the
faithful companion in stagnant waters. Their shells (Fig. 189) are thin,
light, and disk-like in form, rolled round its plane in such a manner as
to render all the turns of the spiral visible from above as well as
below; it is concave on both sides, with an oval, oblong-shaped opening,
and with an operculum or lid. The animal is conformable to the shell in
shape. The visceral mass forms a very elongated cone, which unwinds
itself absolutely, according to the spiral turns of the shell. The foot,
or abdominal locomotive mass, is short, and very nearly round. The head
is sufficiently distinct, and furnished with two very long filiform,
contractile tentacles, having at their base, and on the inner side, a
small organ, which looks like an egg. The mouth is armed in the upper
part with cross-cutting teeth, and in the lower part with a tongue,
bristling with a great number of hooked excrescences.

[Illustration: Fig. 189. Planorbis corneus (Linnæus).]

In habits Planorbis resembles Limnæa: it creeps like it on the surface
of solid bodies, and swims in the water with the foot upwards and the
shell down. It feeds on similar substances, and its eggs are collected
in gelatinous masses also. It passes the winter in a state of torpor,
buried in the mud of the rivers it inhabits.

The principal species is _Planorbis corneus_ (Fig. 189) which is common
in the rivers of England and France.

[Illustration: Fig. 190. Physa castanea (Lamarck).]

Another group of molluscs, which occupy our fresh rivers, and swim with
the shell down and feet up, is represented by _Physa castanea_ (Fig.
190). The genus _Physa_ have an oval, oblong, or nearly globular shell,
very thin, smooth, and fragile, opening longitudinally, narrow above,
with the right edge sharp; the last turn of the spiral being largest of
all.

The animal appears to be intermediate in form between Planorbis and
Limnæa: it is oval in form, and unrolls itself like the Limnæa, but its
tentacles, in place of being triangular and thick like the latter, are
elongated and narrow, like those of Planorbis. These little inhabitants
of fresh water swim with facility, the feet upwards, the shell below,
and like Limnæa, they feed on vegetables.

The fourth family, Limacidæ, containing Testacella and Limax, are
terrestrial pulmonary molluscs, entirely naked, or having only a very
small shell. The Limax varies very considerably in appearance, in
consequence of its extreme contractibility. When seen creeping along on
the surface of the soil, it has nearly the form of a very elongated
ellipse, at one extremity of which is the head; the surface of the body
in contact with the earth is flat, the other convex. Towards the
anterior extremity, and upon the middle of the back, a portion of the
skin projects as if it were detached from the body, and is ornamented
with transverse stripes of various convolutions. This part is named the
cuirass, or buckler, under which the animal can hide its head.

The mouth is a transverse opening in the front of the head; above are
two pairs of tentacles, or horns, immensely retractile, cylindrical, and
terminating in a small button; the lower tentacles are the shorter; the
upper present at their summit a black point, as in _Helix_, which have
sometimes been mistaken for the eyes.

Upon the right side of the cuirass, and hollowed in the thickness of its
edge, which is large and contractile, whose function it is to give
access to atmospheric air, it abuts on an internal cavity, also large,
and is intended to promote respiration. The outer skin, or epidermis,
is rayed in brownish furrows, its surface covered with a viscous
glutinous substance, which permits of the animal creeping up the
smoothest surfaces, locomotion being produced by the successive
contraction and extension of the muscular fibres of the feet.

The internal organization of the Limax is analogous to that already
described in the snails. The taste and smell in the Limaceans differ
only very slightly from those organs in Helix. They are, like the
snails, deaf, and nearly blind. They love humid places; they lodge
themselves in the holes of old walls, under stones, or half-decomposed
leaves, in the crevices of the bark of old trees, and even underground,
coming forth only at night and in the morning; especially after soft
showers in spring and summer. In the garden, after one of these soft
showers, many of these little creatures are sure to be met with in the
more shaded alleys.

The Limax is mostly herbivorous. They seek, above all, for young plants,
fruits, mushrooms, and half-decayed vegetables. They are very voracious,
and cause great ravages in gardens and young plantations, and many are
the devices of the watchful gardener to destroy them. Lime and salt are
their abomination; ashes and fine sand they avoid. They dislike the
noonday sun, and the gardener knows it; he arranges little sheltering
tiles, or planks of wood and stone, under which they retire, where they
are surprised to their destruction.

[Illustration: Fig. 191. Limax rufus (Linnæus).]

There are thirty known species of Limax. Some are remarkable for their
very striking colours. _Limax rufus_ (Fig. 191) is common in woods, and
well known for its large size and its colour of rich yellowish red; it
is known all over Europe, from Norway to Spain.

Among the Limaceans nearly destitute of shells we find _Testacella_
_haliotidea_ (Fig. 192), which is provided with a very small shell
placed at its posterior extremity, just over the pulmonary cavity. This
shell becomes more important in _Vitrina_, already spoken of as forming
the point of transition between Limax and Helix. This passage from
Limaceans entirely destitute of shells to those furnished with a very
small shell, as in _Testacella_, is very exactly indicated by Nature.
_Limax rufus_, spoken of above, presents, under the posterior part of
the cuirass, calcareous, unequal, isolated granulations, which are, so
to speak, the elements, as yet internal, of a shell which is on the
point of being built. Other species in the same genus present under the
cuirass a little rough, imperfect scale, which seems to be produced by a
great number of these calcareous granulations, which show themselves in
an isolated state in _Limax rufus_.

[Illustration: Fig. 192. Testacella haliotidea (Draparnaud).]

The Helicidæ is the fifth family we shall now consider.

It is only necessary to witness the snail as it creeps along the gravel
walks of a garden, or in the damp alleys of a park, in order to see that
it is a being of higher organization than the headless molluscs. The
common snail (_Helix aspersa_) goes and comes; it roams and saunters
after its own peculiar manner, searching for its food or its pleasure;
it has a head and two prominent tentacles, which feel and seem to
express their sensations; it has nerves, a brain, a strong mouth, and a
well-formed stomach.

Without possessing a high order of intelligence, the snail is by no
means imbecile; it knows very well how to choose a tree the fruit of
which is agreeable to it. A fine cluster of grapes, a succulent pear,
which the horticulturist devours with his looks, and hopes to devour
otherwise, is sure to be the identical fruit which will be chosen by our
enlightened depredator, the snail.

The body of the snail is oval, elongated, convex above, flat below. The
convex or upper surface of the body is rugged, in consequence of the
existence of numerous tubercles projecting slightly, and separated by
irregular furrows; its anterior is terminated by an obtuse head, its
posterior more flat and less pointed. All the flat portion, thick, soft,
and upon which the animal moves itself by a creeping motion, bears the
name of the foot. The head is not really very distinct, especially in
the upper part, but the organs with which it is provided are prominent.
These organs are in reality tentacles, although they are more popularly
known as _horns_, especially among children--those charming
ignoramuses--who have been taught to repeat the well-known stanza--

    "Snail, snail, come out of your hole,
    Or else I'll beat you black as a coal"--

which finds its counterpart in all European languages. There are two
pair of these tentacles or horns; one pair quite in front and above, and
another smaller and less forward. The first are distinguished by their
size, and also by a black spot or point at their extremity, which is
sometimes erroneously said to be the eye of the snail.

These tentacles differ in many respects from the same organs in other
molluscs; they are retractile, and can be drawn altogether within the
animal into a sort of sheath, by the contraction of a muscle. At the
anterior extremity of the head we find a sort of plaited opening, which
is the mouth: it is of moderate extent, closed in front by two lips, and
armed with two shear-like organs of horny consistence, one of them being
a sort of rasp, which occupies the plate of the buccal cavity, and may
be called a tongue; the other is a median jaw, placed transversely in
the membranous walls of the palate, terminating in a free edge, armed
with small teeth. This cutting blade, however, executes no movement; but
the lingual organ, pressing all alimentary matter forcibly against its
lower edge, effects their mastication, and enables it to dispose of
fruit, tender leaves, mushrooms, and other substances easily divided.

At the bottom of the mouth is an oesophagus, or gullet, to which
succeeds a stomach of moderate size. The intestine lies in folds round
the liver, which is divided into four lobes, and terminates in a special
orifice.

The little lung of the snail is placed in a cavity, vast for its size,
just above the general mass of the viscera, and occupies all the last
spiral turn of the cavity.

The mechanism of respiration is as follows: The animal inhales the air
into its lung by forcibly dilating the pulmonary orifice, which lies in
the largest spiral turn of the shell. In order to expel the air respired
by the lung, it withdraws its body into the narrower part of the shell,
where it gathers itself up completely, even to its head and feet, and by
this compression of all its little being it expels the air which fills
it. These respiratory movements, however, are not regular, but succeed
each other only at certain intervals. Life would be too hard for the
poor snail were it passed in such violent efforts as would be necessary
if it respired as the larger animals do. In its case the breathing is
intermittent and imperfect; it is merely a rough attempt, as it were, at
respiration, which becomes perfect in some of the higher branches of the
animal kingdom.

The snail has a heart, consisting of a ventricle and auricle, connected
with a well-developed arterial vascular system, while the venous system
is imperfect. In short, the blood only returns from the various parts of
the body to the respiratory apparatus, after traversing lacunæ, or
air-cells, existing between the several organs.

The blood of the snail is of a pale rose colour, slightly tinted with
blue. It has a rudimentary brain, composed of a pair of thick ganglions,
situated above the oesophagus, which are in connection with another pair
of ganglions placed below, which, together, form a sort of collar, or
ring. From this ring springs a great number of nervous cords, which are
distributed to the mouth, the tentacles, the lung, and the heart. The
skin, in those parts covered by the shell, exhibits great sensibility;
it receives a considerable quantity of nervous filament, so that the
sense of touch ought to possess extreme delicacy.

The tentacles, the skin of which is so fine and so sensitive, are the
organs of touch. Other functions are sometimes attributed to them; the
anterior tentacles are sometimes considered to be the organs of smell.
This, at all events, is certain, that the snail is very sensible of
strong odours, and is easily attracted by many plants the odour of which
pleases it.

The black points which terminate the first pair of tentacles have been
considered as eyes: but the existence of a visual organ in the snail is
not quite certain. They are quite insensible to sudden changes of light;
they always travel in the dark, and never recognize obstacles placed
before them. We may add that the snail is destitute of all organs of
hearing. No noise appears to affect it, at least till the noise is so
near as to agitate the air which immediately surrounds it. Indeed, the
snail few has senses; the poor creature is at once blind, deaf, and
dumb.

The snails are male and female in the same individual, or hermaphrodite.
Their eggs are roundish, heavy, and of a whitish colour. The animal
deposits them on the soil in little irregular heaps; at other times it
deposits them one after the other, like the grains of a chaplet, in
holes which it digs in the soil, or in the natural excavations created
by moisture. The eggs are even found in the hollows of old trees; in
fissures of walls or rocks.

When the young _Helix_ issues from the egg, it is already provided with
an extremely thin membranous shell. The timid and tender youth is
conscious of its weakness and full of humility. It rarely trusts itself
out of the obscure hole in which it was hatched; when it does, it is
only at night, dreading the desiccating air, and, above all, the sun's
rays, even with the house it always carries with it for shelter.

This calcareous and velluted house is spiral, which the animal has the
inappreciable advantage of transporting without fatigue. It is light,
and sometimes quite disproportionate to the body of the animal, which it
covers only in that part which contains the viscera and respiratory
organs. The form of the shell is generally much variegated. Some are
flattened, others are orbicular or globose; in some the spiral is very
pointed. The edges of the shell are sometimes simple, sharp, and
pointed; others, on the contrary, thick and inverted, presenting an
edging of great solidity.

The spire is generally rolled up from right to left. A helix shell, the
spiral of which follows the inverse direction, that is, from left to
right, is a rarity much sought after by amateurs.

       *       *       *       *       *

The ancients held snails in especial esteem for the table. The Romans
had many species served up at their feasts, which they distinguished in
categories according to the delicacy of their flesh. Pliny tells us that
the best were imported from Sicily, from the Balearic Isles, and from
the Isle of Capri, the last dwelling-place of the aged Tiberius. The
largest came from Illyria. Ships proceeded to the Ligurian coast to
gather them for the tables of the Roman patricians. The great
consumption led to the establishment of parks (_Cochlearia_, Varro;
_Cochlearum vivariá_, Pliny), in order to fatten the animals, as is now
done with oysters. They were fed for this end upon various plants mixed
with soup; when it was desired to improve the flavour a little wine and
sometimes laurel leaves were added. These parks were formed in humid
shady places surrounded by a foss or a wall. Pliny has even transmitted
to us the name of the inventor of the _Cochleariæ_, a certain Fulvius
Hispinus. Addison describes with details one of these establishments
kept up by the Capuchins at Fribourg in Switzerland, in imitation of the
ingenious Roman gourmet we have named.

Among the Romans, snails were served at the funeral repast. Certain
heaps of their shells, which are found in the cemetery of Pompeii, are
the remains of those funeral festivities with which the inhabitants of
the buried city honoured the tombs of their friends and relations.

The practice of eating snails had fallen into disuse in Europe when, in
the seventeenth century, John Howard, the philanthropist, began to
collect them with the view of reintroducing them as human food. He chose
_Helix Varronis_, which was probably the species cultivated by the
Romans; it surpasses all those of Europe in size, and was found
plentifully in the district of Bagnes, in the Valois. Howard, having
procured the species from Bagnes, found their increase so rapid that the
crops were likely to be devoured by the swarms of molluscs thus brought
together, and steps were at once taken to destroy them. In other parts
of Europe the snail continues to be sought for as an article of luxury.
They are consumed at Vienna in great numbers during Lent, supplies being
brought from the Swiss canton of Appenzell. At Naples a soup made from
_Helix nemoralis_ is sold publicly to the strange population with which
the streets of that city swarm, for the king's pavement is their
bed-chamber, dining-saloon, and work-room. In France, snails are a
valuable resource to the poor in the southern departments.

The flesh of all snails is not alike in a culinary point of view.
Amateurs class as first in quality _Helix vermicula_, called at
Montpelier the Little Hermit, because it buries itself so deeply in its
shell. _Helix aspersa_ (Figs. 193, 194, 195) is thought to be more
tender and delicate. In Provence a species is called _tapada_, that is,
"closed," from the cretaceous deposit with which it closes its shell.

[Illustration: Fig. 193. Helix aspersa (Müller).]

In the north of France, and round Paris, _Helix pomatia_ is the
favourite culinary snail (Fig. 196). This is the species which is used
as a speaking sign-board over the doors of the wine-shops and small
restaurants in the neighbourhood of the Halles, at Paris. Its shell is
globose and tun-shaped, very solid, marked with irregular transverse
stripes of a brownish rust colour, with bands, often nearly effaced, of
a deeper tint, and of the same colour. The animal is large, of a
yellowish grey, and covered with elongated irregular tubercles.

[Illustration: Fig. 194. Helix aspersa (Müller).]

[Illustration: Fig. 195. Helix aspersa (Var. Scalaris).]

Besides _Helix pomatia_, according to Moquin-Tandon, they eat in the
north of France _Helix sylvatica_ and _H. nemoralis_; at Montpelier, as
we have already said, _H. aspersa_ and _H. rhodostoma_; at Avignon,
also, these, along with _H. vermicula_, are favourites. In Provence,
_Helix Pisana_, with _H. aspersa_ and _melastoma_, are preferred. At
Bonifacio, _Helix aspersa_, _H. vermicula_, and, more rarely, _H.
rhodostoma_; and in other localities the smaller species and young
individuals of the larger kinds are employed for feeding poultry.

[Illustration: Fig. 196. Helix pomatia (Linnæus).]

Certain species are also employed for feeding ducks. Thus, in the
neighbourhood of Montpelier, ducks are fed upon _Helix variabilis_ and
_H. rhodostoma_. Some fishes, especially the young salmon, are very
partial to the flesh of snails.

[Illustration: Fig. 197. Helix Mackenzii (Adams).]

[Illustration: Fig. 198. Helix undulata (Ferussac).]

[Illustration: Fig. 199. Helix translucida (Linnæus).]

This very important genera is very numerous in species, which are
distributed in groups according to the form of the shell; that is,
whether it be globulous, as in Fig. 197, tun-bottomed, as in Fig. 198,
plain or biform, as in Fig. 199, or truncated, as in Figs. 200 and 201.
These figures will give the reader some idea of the multiplied and
elegant forms which the shells of _Helix_ sometimes assume.

[Illustration: Figs. 200 and 201. Helix Waltoni (Reeve).]

In connection with the snails (_Helix_), we shall note some kindred
genera which our space only permits us to name. Such is the genus
_Bulimus_, the European species of which are numerous; some of them very
small, others of medium size; of these, _Bulimus sultanus_ (Figs. 204
and 205). In Figs. 206 and 207, the Berry Pupa (_P. uva_), as an example
of another genus, is represented.

[Illustration: Fig. 202. Helix citrina (Linnæus).]

[Illustration: Fig. 203. Helix Stuartia (Sowerby).]

[Illustration: Figs. 204 and 205. Bulimus sultanus (Lamarck).]

Yet another typical species may be noted, which is found abundantly
amid the grass and shrubs near brooks round Paris and elsewhere. It is
_Succinea putris_, presenting a small, thin, diaphanous shell of a pale
amber yellow, marked with close and very fine longitudinal stripes (Fig.
208). The _Achatina zebra_ of Chemnitz is a great snail, which devours
shrubs and trees in Madagascar (Fig. 209). Finally, _Vitrina_, the shell
of which is very small and very thin in some species--so small, indeed,
in _Vitrina fasciata_ (Fig. 210), that the animal cannot fully enter the
shell--occupies a point of transition between _Helix_ and _Limax_.

[Illustration: Figs. 206 and 207. Pupa uva.]

[Illustration: Fig. 208. Succinea putris (Linnæus).]

[Illustration: Fig. 209. Achatina zebra (Chemnitz).]

[Illustration: Fig. 210. Vitrina fasciata (Ed. and Soul).]

In the Pectinibranchial Gasteropods the gills are composed of numerous
leaflets cut like the teeth of a comb, and attached, on one or many
lines, to the upper part of the respiratory cavity. They constitute the
most numerous order of Cephalous Molluscs, comprehending nearly all the
univalve spiral shells, and many others which are simply conical. They
inhabit the sea, rivers, and lakes, and are of all sizes. The most
remarkable genera which we shall describe belong to the family of
_Trochoïdæ_ and _Buccinoïdæ_.

The fourth order of Gasteropods, Prosobranchiata, which includes the
Pecteni Branchiata, is distinct in the sexes, has the branchiæ
pectinated, and the mantle forms a vaulted chamber over the back of the
head. It is divided into two sections and twenty-one families. The first
section, _Holostomata_, contains the sea-snails. The first family we
shall treat of is the _Chitonidæ_, containing _Chitonellus_ and
_Chiton_.

[Illustration: Fig. 211. Chiton magnificus (Deshayes).]

The _Chitons_ are very singular creatures, destitute of eyes, of
tentacles, and without jaws; they bear upon their back in place of a
shell a cuirass composed of imbricated and movable scales. They have the
power of elongating and contracting themselves like the snails. They
roll themselves up into a ball like the woodlouse. They adhere with
great force to the rocks, preferring those places most exposed to the
beating waves. _Chiton magnificus_ (Fig. 211) is widely distributed.

The second family, _Dentaliadæ_, affords the curious _Dentalium_, or
tooth shell.

The _Patellidæ_, or Limpets, constitute a very numerous family,
distinguished at once by the form and structure of the animal, and by
that of the shell. Linnæus called it Patella, _i. e._, a deep dish or
knee-cap.

The shells of the Patellidæ, our third family, are univalve, oval, or
circular, non-spiral, but terminating in an elliptic cone, concave and
simple beneath, non-pierced at the summit, entire and inclined
anteriorly. They are smooth, or ornamented on the sides with ridges
radiating from the summit, and often covered with scales; the edges are
frequently dentate. The colours much varied. The interior is very
smooth, and remarkable for the brilliancy and lustre of its tints.

The head of the animal is furnished with two pointed tentacles or horns,
having an eye at the external base of each. The body is oval and nearly
circular, conical, or depressed. The foot is in the form of a thick
fleshy disk. Certain lamellar branchiæ are arranged in series all round
the body.

The Limpets dwell upon the sea-shore, in the parts alternately covered
and uncovered by the waves. They are almost always attached to rocks, or
other submerged bodies, to which they adhere with great tenacity. If the
common Limpet (_Patella vulgata_) is alarmed before any attempt is made
to dislodge it, no human force, pulling in a direct line, can remove it,
and it can sustain without being crushed a weight of many pounds. It
holds on by the great quantity of vertical fibres of the foot, which in
raising the median part forms in the centre a sort of sucker. It is the
celebrated experiment of the Magdeburg cups which these little molluscs
realise by their vital action.

These animals bury themselves in the chalky rocks to the depth of two or
three lines; when they are dispersed, they are observed constantly to
return to the same place. Their movements are, besides, extremely slow;
the advance of the Limpet being only perceived by watching the slow
upheaval of the shell above the plane of its position. It is supposed,
from the mouth being armed on its upper edge with a large semi-lunar,
horny, cutting tooth, and in its lower part from having a tongue
furnished with horny hooks, and from their inhabiting in great numbers
places covered with marine plants, that their food is chiefly vegetable.

[Illustration: Fig. 212. Patella cærulea (Lamarck).]

[Illustration: Fig. 213. Patella umbella (Gmel.).]

The poorer inhabitants of the coast eat limpets when they have nothing
else, but their flesh is singularly coriaceous and indigestible.

They are found in every sea; but are, however, found to be larger as
well as more numerous, and much richer in colour, in Equatorial seas,
and especially in the southern hemisphere, than in European seas. They
attain, in fact, their maximum of development here; for in the Straits
of Magellan species are found as large as a slop-basin, which the
natives use for culinary purposes.

The common Limpet is thick, solid, oval, and nearly circular, generally
conical, and covered with a great number of very fine stripes. Its
colour is of a greenish grey, uniform above, and of a greenish yellow
inside. It is abundant in the Channel and on Atlantic coasts.

The Blue Limpet, _Patella cærulea_ (Fig. 212), from St. Helena, has an
oval shell, broadest behind, moderately thick, depressed, flattened,
covered with angular wrinkles, and dentate on the edge. It is of a
spotted green outside and of a fine glossy blue within.

[Illustration: Fig. 214. Patella granatina (Linnæus).]

[Illustration: Fig. 215. Patella barbata (Lamarck).]

Other very elegant species are _Patella umbella_ (Fig. 213), from the
African coast. _Patella granatina_ (Fig. 214), the ruby-eyed Limpet from
the Antilles; _Patella barbata_, the bearded Limpet (Fig. 215); and the
long spined Limpet, _Patella longicosta_ (Figs. 216 and 217).

[Illustration: Figs. 216 and 217. Patella longicosta (Lamarck).]

The fourth family, _Calyptræidæ_, types _Pileopsis_ and _Calyptræa_, was
classed by the older conchologists with _Patella_. _Pileopsis
Hungaricus_, the Hungarian bonnet shell, is rather abundant on some
parts of the British coast.

The fifth family, _Fissurellidæ_, contains _Parmophorus_, the
duck's-bill-limpet of Australia, and _Fissurella_, the key-hole-limpet,
which is remarkable for the opening of the apex of the shell.

The sixth family, _Haliotidæ_, contains _Ianthina_, _Scissurella_, and
_Haliotis_.

[Illustration: Fig. 218. Ianthina communis (Lamarck).]

The attention of naturalists has long been directed to a curious mollusc
known under the name of _Ianthina communis_ (Fig. 218); its body is
globular, and it presents an opening in front without contracting itself
in order to form the head, which is long and trumpet-shaped, terminating
in a large buccal opening, furnished with horny plates, and covered with
little hooks; and two conical tentacles, slightly contracted, but very
distinct, each bearing at their external base a long peduncle. The foot
is short, oval, divided into two parts: the anterior, concave and
cup-shaped; the posterior, flat and fleshy. It is this foot, which bears
a vesiculous mass like foam, which gives its peculiar character to the
pretty mollusc. The mass consists of a great number of small bladders,
which combine to keep the animal on the surface of the water. The shell
is light, transparent, violet-coloured, and very much resembles the
shell of the Helix. The _Ianthinas_ inhabit the deep sea, and often form
bands of very great extent. Messrs. Quoy and Gaimard have seen legions
of Ianthinas driven by the current. They have sailed during many days
through these wandering tribes, which would be the sport of every gale
if they could not, by drawing their heads within their shells and
contracting their natatorial vesicles, diminish their volume and
increase their weight at will, so as to sink quietly to the bottom of
the water till the tempest was over. The _Ianthina_ possesses a liquid
of a dark violet colour, which is believed by many naturalists to have
been one of the purple dyes known to the ancients, if not the purple of
Tyre: it is very common in the Mediterranean.

_Haliotis_, the ear-shell, is remarkable for its brilliant colours, and
for a line of singular perforations in many of the species.

The seventh family, _Turbinidæ_, contains _Trochus_, _Turbo_,
_Protella_, _Monodonta_, and _Delphinula_.

The genus _Trochus_ are found in all seas, and near to the shore in the
clefts of rocks, especially in places where sea-weeds grow luxuriantly.
Some of these thick, cone-shaped shells are extremely beautiful, being
richly nacred inside, and remarkable for the beauty and diversity of
colour exhibited. Generally smooth, the great spiral is, nevertheless,
sometimes edged with a series of regular spines. The form is conical,
the spiral more or less raised, broad and angular at the base; the
opening entire, depressed transversely, and the edge disunited in the
upper part.

[Illustration: Fig. 219. Trochus niloticus (Linnæus).]

[Illustration: Fig. 220. Trochus virgatus (Gmel.).]

[Illustration: Fig. 221. Trochus inermis (Gmel.).]

[Illustration: Fig. 222. Trochus Cookii (Chemnitz).]

[Illustration: Fig. 223. Trochus imbricatus (Gmel.).]

[Illustration: Fig. 224. Phorus conchyliophorus (Borfu).]

The animal which inhabits this shell is also spiral; its head is
furnished with two conical tentacles, having at their base eyes borne on
a peduncle; its foot is short, round at its two extremities, edged or
fringed in its circumference, and furnished with a horny operculum,
circular and regularly spiral.

The family is divided into many sub-genera. Among the _Trochi_, properly
so called, we may notice _Trochus niloticus_ (Fig. 219), _T. virgatus_
(Fig. 220), _T. inermis_ (Fig. 221), and _T. Cookii_ (Fig. 222).

[Illustration: Fig. 225. Turbo margaritaceus (Linnæus).]

[Illustration: Fig. 226. Turbo argyrostomus (Linnæus).]

[Illustration: Fig. 227. Turbo marmoratus (Linnæus).]

[Illustration: Fig. 228. Turbo undulatus (Chemnitz).]

The genus _Turbo_ are very generally diffused, being found on every
shore, where they cling to rocks beaten by the waves. About fifty
species are known, some of them large shells, others very small. _Turbo
margaritaceus_ (Fig. 225) is large, thick, and weighty, round-bellied,
and deeply furrowed; in colour it is yellow, or rust-coloured, marked by
square brown spots. _Turbo argyrostomus_, the Silver-mouthed Turbo (Fig.
226), is still larger, with protecting spines on the top of its larger
spiral. _Turbo marmoratus_ (Linnæus), the Marbled Turbo (Fig. 227), is
the largest shell in the group. It is marbled, green, white, and brown,
outside, and superbly nacred within. The Gold-mouthed Turbo is so named
from its nacre being of a rich golden yellow. The Wavy Turbo (_T.
undulatus_), (Fig. 228), vulgarly known as the Australian Serpent's
Skin. The shell is white, ornamented with longitudinal waving flexible
lines of spots of green, or greenish-violet. _Turbo imperialis_ (Fig.
229), from the Chinese seas, is green without, and brilliantly nacred
within; it is vulgarly known as the paroquet.

The _Turbos_ are found in the North seas, in the Channel, and on the
Atlantic coast. The animal is eaten in nearly all the sea-ports of the
Channel.

[Illustration: Fig. 229. Turbo imperialis (Gmel.).]

[Illustration: Fig. 230. Rotella Zealandica.]

_Rotella Zealandica_, from the Indian Ocean, whose shell, represented in
Fig. 230, presents the most lively colours, forms one of a genus by no
means numerous in species.

Near to the _Trochi_ and _Turbos_ in the system are the _Monodonta_.

The _Monodonta_ are elegantly-marked shells, belonging to the seas of
warm countries. _M. Australis_ (Fig. 231) is a native of Australian
seas. _M. labia_ (Fig. 232) is a small brown shell, with white spots,
which is very common on the shores of the Mediterranean.

[Illustration: Fig. 231. Monodonta Australis (Lamarck).]

[Illustration: Fig. 232. Monodonta labia (Lamarck).]

The eighth family is _Neritidæ_, of which we give as types, _Pileolus_
and _Nerita_. The hoof-shells, or Nerites, are numerous and pretty, and
in external form approach _Turbo_.

[Illustration: Fig. 233. Delphinula sphærula (Kiener).]

Of the _Delphinula_ only a small number of living species are known.
They are natives of the Indian Ocean, and remarkable for their numerous
spines and the asperity of their shell (Fig. 233).

The ninth family, _Paludinidæ_, contains _Ampullaria_, the idol snail of
India, and the widely distributed _Paludina_.

Our tenth family, _Littorinidæ_, contains _Solarium_, and the
periwinkles, _Littorina_ and _Phorus_, example, _P. Conchyliophorus_
(Fig. 224).

The genus _Imperator_ belongs to the _Turbinidæ_, and as examples of it
we may instance the Spurred Trochus, _Imperator stella_, which is
studded with radiating spines (Fig. 234), and _Imperator stellaris_
(Fig. 235); they are natives of the Australian seas. _Imperator
imperialis_, vulgarly called the Royal Spur, and _Trochus_ or _Rotella
Zealandica_ (Fig. 230), the New Zealand Spur, the spiral turns of which
are sculptured in descending furrows, and studded with imbricated
scales, which form a projecting edging round the margin of the shell,
and give it a radiating form. This species is of a violet brown above
and white below, and is still rare in collections.

[Illustration: Fig. 234. Imperator stella (Lamarck).]

[Illustration: Fig. 235. Trochus stellaris (Gmel).]

The Sun-dial (_Solarium_), recognized by its deep umbilicus, wide and
funnel-shaped, in the interior of which may be seen the little crenated
teeth which follow the edge of every turn of the spiral up to the top.
In most collections of these pretty shells we find the Staircase-shell
(_Solarium perspecticum_) of Lamarck, from the Indian Ocean (Figs. 236,
237), the diameter of which is sometimes two inches and a half. The
Australian Sun-dial (_S. variegatum_, Linnæus, Fig. 238) is another
species frequently seen in collections: it is as much variegated above
as below, of a white and rusty brown. The minute trellised Sun-dial,
which is only ten lines in diameter, comes from the coast of Tranquebar.

[Illustration: Fig. 236. Solarium perspecticum.]

[Illustration: Fig. 237. Solarium perspecticum.]

[Illustration: Fig. 238. Solarium variegatum.]

[Illustration: Fig. 239. Turritella replicata (Linnæus).

Fig. 240. Turritella angulata (Sowerby).

Fig. 241. Turritella sanguinea (Reeve).

Fig. 242. Turritella goniostoma.

Fig. 243. Turritella terebellata (Lamarck).]

The eleventh family, _Turritellidæ_, types _Vermetus_ and _Turritella_,
which last is a numerous family, being found in every sea. All these
shells, as their name indicates, represent a winding pyramid,
terminating in a sharp point, some of them having fluted spirals, others
rounded, angular, or flat, and some of them elegantly pencilled. Figs.
239 to 243 represent some of the varied forms they assume.

The twelfth family, _Melaniadæ_, types, _Paludomus_ and _Melania_,
fresh-water genera.

The thirteenth family, _Cerithiadæ_, types, _Aporrhais_ and _Cerithium_.

[Illustration: Fig. 244. Cerithium fasciatum (Brug.).]

[Illustration: Fig. 245. Cerithium aluco.]

[Illustration: Fig. 246. Cerithium giganteum (Lamarck).]

_Cerithium_ is a marine shell, which is found in muddy bottoms, on
ships, and more frequently at the mouths of rivers, but rarely beyond
the point to which the tide reaches. The genus is numerous in species.
Such are _Cerithium fasciatum_ (Fig. 244) and _Cerithium aluco_ (Fig.
245).

The Giant Cerithium, _Cerithium giganteum_ (Fig. 246), is the living
analogue of a magnificent fossil species belonging to the tertiary
formation. The single known example of this species belongs to the
Delessert Museum at Paris. A manuscript note by Lamarck, attached to
this specimen, relates that this shell was first brought to Dunkirk in
1810 by an Englishman, one of the crew of an English ship. The English
sailor had drawn it up from the bottom of the sea with the sounding-lead
from a bed of rocks off the coast of Australia.

The fourteenth family, _Pyramidellidæ_, contains _Chemnitzia_ and
_Pyramidella_, extremely pointed shells.

The fifteenth family, _Naticidæ_, contains _Lamellaria_ and _Natica_;
the last of which is found in most seas.

The second section of the _Prosobranchiata_ is termed _Siphonostomata_,
which are characterized by a spiral imperforate shell, the animal of
which has sometimes a horny operculum, and is furnished with an elastic
trunk, the margin of the mantle acting as a siphon. They are
carnivorous.

The first family is the _Cypræidæ_, containing the well-known _Cypræa_
and _Ovulum_.

The Cowries, or _Cypræa_, are brilliant, smooth, and polished,
oval-shaped, or oblong convex, with edges rolling inwards and
longitudinal openings, narrow, arched, dentate on both edges, and
notched at the extremities. The spiral, placed quite posteriorly, is
very small, and often hidden by a calcareous bed of a vitreous
appearance.

It is now known that the form and colouring of the shells vary very
considerably, according to the age of the animal: so much so, indeed,
that the same species examined at various stages of its growth would
almost seem to belong to species and even to genera essentially
different.

The young cowries are thin, conical, elongated; with conspicuous spiral,
and large openings. The right edge soon becomes thicker, and folds
itself inwardly; the opening is narrowed; finally, the spiral is
unfolded in successive folds from the right edge, and by successive
deposits of the vitreous matter we have spoken of the opening is
gradually contracted, its extremities hollowed out, its edges
disconnected, and the shell, until now only shaded in pale tints,
assumes its most brilliant colours, disposed in bands or spots, as
exhibited in PL. XXII., in which Figs. I. and II. are the adult shells,
and Fig. III. the young shell, of _Cypræa Scottii_.

[Illustration: PLATE XXII.--Cypræadæ.

Adults.

    I. Cypræa Scottii. (Broderip.)
    II. Cypræa Scotti. (Broderip.)

Young.

    III. Cypræa. (Broderip.)
    IV. Cypræa mappa.
    V. and VI. Cypræa histrio. (Linn.)
    VII. Cypræa tigris. (Linn.)
    VIII. and IX. Cypræa argus. (Linn.)
]

The animal which inhabits this shell is elongated, and is provided with
a well-developed mantle, furnished on the inside with a band of
tentacles; it is able to fold itself up in its shell in such a manner as
to be enveloped all round. The head is provided with two very long
conical tentacles, each having a very large eye, in which a pupil and
iris can be distinguished. The foot is oval, elongate, and without
operculum, and is well represented in _Cypræa tigris_ (Fig. 247). The
cowries are found at a little distance from the shore, generally in
clefts of the rocky bottoms; but sometimes they bury themselves in the
sand. They are timid, shun the light, and only leave their retreats to
creep about in search of food, which appears to be exclusively animal.
These magnificent molluscs are natives of every sea. One small creature
lives in the British Channel; another and much larger species is found
in the Adriatic; but the Indian Ocean is the home of the largest and
finest species of these shells.

[Illustration: Fig. 247. Cypræa tigris (Linnæus).]

[Illustration: Fig. 248. Cypræa coccinella (Lamarck).]

As objects of curiosity and ornament these shells have been much in
request in all ages. The inhabitants of the Asiatic coast make
bracelets, collars, amulets, and head-dresses of them, and use them to
ornament boxes and harness. In New Zealand the chiefs carry a rare and
choice species, suspended from the neck, as a badge of their rank or
sign of distinction. This is _Cypræa aurantium_. In some parts of India
and Africa a very small species of Cowrie passes as current money. These
shells are, indeed, extremely numerous, and we can only find room for
very brief descriptions of a few of the best known among them.

The Waving and Zigzag Cowries, whose native country is unknown, are
beautifully ornamented with waving and broken lines, as we see them in
Figs. 249 to 252.

[Illustration: Figs. 249 and 250. Cypræa undata (Lamarck).]

[Illustration: Figs. 251 and 252. Cypræa zigzag (Linnæus).]

The New Zealand Cowrie, of which we have spoken above, is nearly
globular, of a uniform orange colour above, and white below; the teeth
of the opening are of a bright orange. The shell is rare, and much
sought after.

The Money Cowrie, _Cypræa moneta_ (Figs. 253 and 254), is a little oval
shell, depressed, flat below, with very thick edges and slightly waving.
It is of a uniform yellowish white colour, sometimes citron-yellow above
and white below. There are usually twelve teeth in the opening. It comes
from the Indian Ocean, the Maldivian Isles, and the Atlantic Ocean.

[Illustration: Figs. 253 and 254. Cypræa moneta (Linnæus).]

[Illustration: Fig. 255. Cypræa Madagascariensis (Gmel.). (1 and 2).]

This shell, so common in collections, is gathered by the women on the
shore of the Maldivian Isles, three days after the full moons and before
the new moons; it is afterwards transported to Bengal, to India, and
Africa, where, as we have already said, it is used by the negroes and
other natives as money.

The Madagascar Cowrie, _Cypræa Madagascariensis_ (Fig. 255), and the
Granular Cowrie, _Cypræa nucleus_ (Figs. 259 and 260), are beautifully
marked species, having the general appearance of the Cowrie.

[Illustration: Fig. 256. Cypræa capensis (Gray).]

[Illustration: Figs. 257 and 258. Cypræa testudinaria (Linnæus).]

The species most abundant in the Channel is the little _Coccinella_,
already mentioned; it is very small, oval, tun-bellied, the opening
dilated in front with smooth transverse stripes of greyish, tawny, or
rose-colour, with or without spots.

[Illustration: Figs. 259 and 260. Cypræa nucleus (Linnæus).]

[Illustration: Fig. 261. Cypræa pantherina (Sol.).]

_Cypræa mappa_ (PL. XXII., Fig. IV.) is oval-shaped, swelling below its
sides, well-rounded, ornamented with small white spots below, with a
dorsal branching line above; the interior is violet colour, with
thirty-six teeth on one side, and forty-two on the other. It belongs to
the Indian Ocean.

The Harlequin Cowrie, _Cypræa histrio_ (Figs. V. and VI.), from the
coast of Madagascar, is ornamented with white spots very closely
arranged, and much circumscribed above, with black spots upon the sides.
The under side is violet.

[Illustration: Fig. 262. Natural size of Ovulum oviformis (Lamarck).]

A very fine species, which is very common in collections, is found in
the Indian Ocean, from Madagascar to the Moluccas--the Tiger Cowrie,
already figured with its inhabitant. This shell (Fig. VII.) is large,
oval, tun-bellied, thick, and convex, of a bluish white, ornamented with
numerous broad, black, round spots, much scattered, and a straight
dorsal line, brown above, and very white below. It has generally
twenty-three teeth on each edge, quite white. Somewhat resembling the
Tiger Cowrie is the _Cypræa pantherina_ (Fig. 261), which is perhaps a
variety of the same species. Another remarkable species is _Cypræa
argus_, as represented in PL. XXII. (Figs. VIII. and IX.)

[Illustration: Fig. 263. Natural size of Ovulum cornea (Lamk.).]

The genus _Ovulum_, so called from their egg-shaped form, occupy a place
near the cones in some systems. The shell is highly polished, white or
rose-coloured, oblong or oval, convex, attenuate, and acuminate at the
extremities without apparent spiral, the edges milled within the long,
narrow, and curved opening, with teeth upon the left edge, and with a
few ripples on the right edge. The Ovula are inhabitants of the Indian
Ocean and Chinese Seas. Some few species, however, belong to the
Mediterranean and the Black Sea. The three species represented in Figs.
262, 263, and 264, present very singular contrasts of form and size.

[Illustration: Fig. 264. Ovulum volva (Linnæus).]

The second family, _Volutidæ_, contains _Mitra_ and _Voluta_.


MITRA.

The Mitres are so called from their resemblance to the bishop's mitre.
They are natives of warm climates, such as the Indian Ocean, the
Australian Seas, and the Moluccas. The shell of the Mitra is long,
slender, and spiral, the spire ending in a point at the summit; the
opening is small, narrow, and triangular, and notched in front. The
inhabitant of the shell has the peculiarity of projecting from its mouth
a sort of cylindrical trunk, which is long, very extensible as well as
flexible, and probably prehensile, the use of which is only the subject
of surmise. _Mitra episcopalis_ (Fig. 265), from the Indian Ocean, is
white, ornamented with square spots of a fine red, and capable of high
polish.

[Illustration: Fig. 265. Mitra episcopalis (Lamarck).]

[Illustration: Fig. 266. Mitra papalis (Lamarck).]

_Mitra papalis_ (Fig. 266) has dentiform folds round the opening, which
also crown each turn of the spiral; the spots are smaller, and much
more numerous and varied in form than those of _M. episcopalis_.

In the genus _Voluta_, from _volvere_, to turn, the shell is oval, more
or less tun-bellied. A spiral rising, slightly mammelate, the opening
large, the edges notched, without channel; the columellar edge is
lightly excavated and arranged in oblique folds. The right edge is
arched, thick, or cutting, according to the species.

The animal has a large head, provided with two tentacles. The mouth
terminates in a thick trunk furnished with hooked teeth. The foot is
very large, furrowed in front, and projecting from all parts of the
shell, but without operculum. The Volutæ live on the sands near the
shore; sometimes they are found high and dry, left by the retreating
tide. Their shells, of various forms, are ornamented with the most
lively colours, the surface covered with irregular lines, the tint of
which is generally in strong contrast with that of the ground.

Among the more remarkable species illustrated in PL. XXIII., we may
note: Fig. I., _Voluta undulata_; Fig. II., _Voluta cymbium_; Fig. III.,
_Voluta delessertii_; Fig. IV., _Voluta musica_; Fig. V., _Voluta
imperialis_; Fig. VI., _Voluta scapha_; and Fig. VII., _Voluta
vexillum_.

The third family, _Conidæ_, contains _Pleurostoma_ and _Conus_.

The genus _Conus_ is especially rich in species, as well as numerous in
many individuals. They are much sought after by collectors, many being
rare, and so command high prices. The shells belonging to this group
present a very remarkable uniformity of shape, at the same time that the
colours are very fine, and much varied in design. The shell is thick,
solid, inversely conical, wreathing spirally from the base to the apex,
the spiral being generally short, the last turn constituting alone the
greater part of the surface of the shell. The opening extends nearly
along its whole length, occupying all the height of the last whirl. It
is always narrow, its edges quite parallel; the columella presents
neither fold nor curvature; the right edge is plain, sharp, and thin,
detached from the front of the last spiral by a sloping hollow, more or
less deep.

[Illustration: PLATE XXIII.--Voluta.

    I. Voluta undulata. (Lamarck.)
    II. Voluta cymbium. (Linn.)
    III. Voluta Delessertii. (Petit.)
    IV. Voluta musica. (Linn.)
    V. Voluta imperialis. (Lamarck.)
    VI. Voluta scapha. (Gmel.)
    VII. Voluta vexillum. (Chem.)
]

[Illustration: PLATE XXI.--Conus.

    I. Conus imperialis. (Linn.)
    II. Conus geographus. (Linn.)
    III. Conus tessellatus. (Born.)
    IV., V., and VI. Conus ammiralis. (Linn.)
    VII. Conus nobilis. (Linn.)
    VIII. Conus textile. (Linn.)
    IX. Conus gloria maris. (Chemn.)
]

The animal which inhabits the Conus shell creeps upon a foot, elongated,
narrow, truncate in front, furnished behind with a horny rudimentary
operculum, altogether insufficient to cover the opening. The head, which
is large, is elongated into a little snout, or muzzle, at the base of
which rises on either side a conical tentacle, having an exterior eye
upon its anterior extremity. At the extremity of the muzzle is the
mouth, which is armed within with numerous horny hooks, inserted in the
tongue. A cylindrical syphon, reversing itself in the shell, serves the
purpose of carrying water to the branchiæ or gills. The shells inhabit
the seas of warm countries, especially those lying between the Tropics,
where they affect sandy coasts, with a depth of ten to twelve fathoms of
water.

Among the species bearing a spiral crown, we may mention the rare _Conus
cedonulli_, of which several varieties are known, which come from the
South American Seas and the Antilles.

_Conus hebraica_, from the shores of Asia, Africa, and America, is a
common species. It is white with black spots, which are nearly square,
arranged in transverse bands.

In PL. XXI. we have represented some interesting species. _Conus
imperialis_ (Fig. I.) is a fine species, of white colour, with bands of
a greenish yellow or tawny colour, ornamented with transverse,
cord-like, articulated lines of white and brown. One of the largest
species is _Conus geographus_ (Fig. II.), which sometimes attains the
length of six or seven inches; it is shaded white and brown.

Among the non-crowned species, we have represented in Fig. III. _Conus
tessellatus_, common in the Indian Ocean. Its anterior part is violet in
the interior. The spots with which it is surrounded are of a fine red or
scarlet, or, in short, a red lead colour upon a white ground.

_Conus ammiralis_, of which three varieties, Figs. IV., V., and VI., are
natives of the seas which bathe the Moluccas; they are beautifully
marked varieties, of a brownish citron colour, marked with white spots
nearly triangular, with tawny bands painted in very fine tracery. This
species has been, and is still, much sought after by collectors, and
presents many varieties besides those represented.

Among the shells, which seem almost ready to become cylindrical, may be
noted _Conus nobilis_ (Fig. VII.), a rare shell of yellowish colour
approaching citron, ornamented with white spots. The golden drop, _Conus
textile_ (Fig. VIII.), is yellow in colour, ornamented with waving
longitudinal lines of brown, and white corded spots edged with tawny
colour. The glory of the sea, _Conus gloria maris_ (Fig. IX.), is white
in colour, banded with orange, and reticulated with numerous triangular
white spots edged with brown. This is a native of the East Indies, and
one of the most beautiful shells of the whole group.

The fourth family, _Buccinidæ_, contains numerous genera, as examples of
which we may instance _Oliva_, _Harpa_, _Cassis_, _Purpura_, _Nassa_,
_Terebra_, _Eburna_, and _Buccinum_.

_Oliva_ is so named from their resemblance in form to the olive. Their
nearly cylindrical shell is slightly spiral, polished, and brilliant as
the Cowries; its opening is still long and narrow, strongly notched in
front, its edge columellar, swollen anteriorly into a kind of cushion,
and striped obliquely in all its length.

[Illustration: Fig. 267. Oliva erythrostoma (Lamarck).]

[Illustration: Fig. 268. Oliva porphyria (Linnæus).]

[Illustration: Fig. 269. Oliva irisans (Lamarck).]

[Illustration: Fig. 270. Oliva Peruviana (Lamarck).]

These Molluscs belong to the seas of warm countries, where they frequent
the sandy bottoms and clear waters. They creep about with much agility,
reversing themselves quickly when they have been overturned; they live
upon other animals, and are flesh-eaters. They are, in fact, taken at
the Isle of Tranu by using flesh as bait. The colours of the shell are
very varied, and sometimes fantastically streaked. _Oliva erythrostoma_
(Fig. 267) is ornamented externally with flexual lines of a yellowish
brown, with two brown bands, combined with the fine yellowish tint of
gold colour within. _Oliva porphyria_, from the Brazil coast (Fig. 268),
presents lines of a reddish brown, regularly interlaced with spotted
large brown marks, upon a flesh-coloured ground. _Oliva irisans_ (Fig.
269) is painted in zigzag lines, close and brown, edged with
orange-yellow, and with two zones of darker brown, and reticulated.
_Oliva Peruviana_ (Fig. 270) is furrowed with regularly spaced bands.

In the casque, _Cassis_, the shell is oval, convex, and the spiral of
considerable height. The longitudinal opening narrow, terminating in
front in a short channel, which becomes suddenly erect towards the back
of the shell, as in _Cassis glauca_ (Fig. 271), a fine shell from the
Moluccas. The columella is folded or toothed transversely, as in Fig.
272 (_Cassis rufa_); the right edge thick, furnished with a sort of pad
externally, and dentate within. This shell is from the Indian Ocean, and
is of a fine purple colour, varied with black above; the edges of the
opening being of a coral red colour, the teeth alone being white.

[Illustration: Fig. 271. Cassis glauca (Linnæus).]

[Illustration: Fig. 272. Cassis rufa (Linnæus).]

[Illustration: Fig. 273. Cassis canaliculata (Brugières).]

[Illustration: Figs. 274 and 275. Cassis Madagascariensis (Lamarck).]

The head of the animal is large and thick, furnished with two conical
elongated tentacles, at the base of which are the eyes. The mantle is
ranged outside the shell, falling back upon the edges of the opening,
and terminating at its anterior extremity in a long cylindrical channel,
cloven in front, and passing by a hollow at the base into the bronchial
cavity. The foot is large, and furnished with a horny operculum.

[Illustration: Fig. 276. Cassis zebra (Lamarck).]

These animals keep near the shore, in shallow water. They walk slowly,
and often sink themselves into the sand, where they prey upon small
bivalves. They are not numerous in species; but specimens from the
Indian Ocean are often large and beautifully marked. The shells of the
less marked species are frequently used in India as lime; and employed
as mortar, under the name of Chunam.

Our space only permits us to mention, among the more curious, _Cassis
canaliculata_ (Fig. 273), two varieties of _Cassis Madagascariensis_
(Figs. 274 and 275), and the curious _Cassis undata_ (Martini), _Zebra_
(Lam.), or Zebra-marked Casque (Fig. 276).


PURPURA.

The Purpuras have a classical name and history, having furnished the
Greeks and Romans with the brilliant purple colouring matter which was
reserved for the mantles of patricians and princes. The Purpura is an
oval shell, thick pointed, with short conical spiral, as in _Purpura
lapillus_ (Fig. 277). In some it is tubercular or angular, the last turn
of the spiral being larger than all the others put together. The opening
is dilated, terminating at its lower extremity in an oblique notch. The
columellar edge is smooth, often terminating in a point; the right edge
often digitate, thick internally, and folded or rippled.

The animal presents a large head, furnished with two swollen conical
tentacles, close together, and bearing an eye towards the middle of
their external side. Its foot is large, bilobate in front, with a
semicircular horny operculum.

The Purpuras inhabit the clefts of rocks in marine regions covered with
algæ. On occasions they bury themselves in the sand. They creep about by
the help of their foot in pursuit of bivalves, which they open by means
of their short snout. They are found in all seas; but the larger species
and greatest numbers come from warm regions, more especially from the
Australian seas.

The Purpura of the ancients was not, as is generally thought, a
vermilion red, but rather a very deep violet, which at a later period
came to have various shades of red. The secret of its preparation was
only known to the Phoenicians, that being most esteemed which came from
Tyre. An English traveller, Mr. Wilde, has discovered on the eastern
shores of the Mediterranean, near the ruins of Tyre, a certain number of
circular excavations in the solid rock. In these excavations he found a
great number of broken shells of _Murex trunculus_. It is probable that
they had been bruised in great masses by the Tyrian workmen for the
manufacture of the purple dye. Many shells of the same species are found
actually living on the same coast at the present time.

Aristotle, in his writings, dwells upon the purple. He says that this
dye is taken from two flesh-eating molluscs inhabiting the sea which
washes the Phoenician coast. According to the description given by the
celebrated Greek philosopher, one of these animals had a very large
shell, consisting of seven turns of the spiral, studded with spines, and
terminating in a strong beak; the other had a shell much smaller.
Aristotle named the last animal _Buccinum_. It is thought that the last
species is recognized in the _Purpura lapillus_ (Fig. 277), which
abounds in the Channel. Réaumur and Duhamel obtained, in fact, a purple
colour from this species, which they applied to some stuffs, and found
that it resisted the strongest lye. The genus _Murex_ is supposed to
have been the first species indicated by Aristotle.

Up to the present time, the production of the purple remains a mystery.
It was long thought this fine dye was furnished by the stomach, liver,
and kidneys; but M. Lacaze-Duthiers has demonstrated that the organ
which secretes it is found on the lower surface of the mantle, between
the intestines and the respiratory organs, where it forms a sort of
fascia, or small band. The colouring matter, as it is extracted from the
animal, is yellowish; exposed to the light, it becomes golden yellow,
then green, taking finally a fine violet tint. While these
transformations are in progress a peculiarly pungent odour is
disengaged, which strongly reminds one of that of assafoetida. That
portion of the matter which has not passed into the violet tint is
soluble in water; when it has taken that tint it becomes insoluble. The
appearance of the colour seems provoked rather by the influence of the
sun's rays than by the action of the air. The matter attains its final
colour, in short, in proportion to the power of the sun's rays.

It is a question how far the colour evolved under the solar rays remains
indelible. It is known that the contrary is the case with the colouring
matter of the cochineal insect, which changes very quickly when exposed
to the sun. It is probably the remarkable resistance it opposes to the
rays of the sun which recommended it to the ancients. The patricians of
Rome, and the rich citizens of Greece and Asia Minor, loved to watch the
magical reflections of the sun on the glorious colour which ornamented
their mantles.

But to return to our humble shells. _Purpura lapillus_ (Fig. 277) is a
thick shell, oval acute, with conical spiral, generally of a faded or
yellowish white, zoned with brown, and more or less spotted.

[Illustration: Fig. 277. Purpura lapillus.]

[Illustration: Fig. 278. Purpura patula.]

_Purpura patula_ (Fig. 278) is very common in the Philippines, and is
one of the handsomest species; its geographical distribution has been a
subject of much controversy.

_Purpura consul_ (Fig. 279) is one of the large shells, and of a fine
salmon colour, with brown bands and a corona of spines.

The _Buccinums_ resemble the Purpura in many respects. Their shell is
oval or conical, much notched in front. They inhabit every sea,
especially those of Europe. The animal has a small flat head, furnished
with lateral tentacles or horns, bearing the eyes upon an external
swelling, situated near their central length. We need only refer to Fig.
280, _Buccinum senticosum_, and _Buccinum undatum_ (Fig. 281), for their
general form, the well-known whelk of our markets.

[Illustration: Fig. 279. Purpura consul.]

[Illustration: Fig. 280. Buccinum senticosum (Linnæus).]

[Illustration: Fig. 281. Buccinum undatum (Linnæus).]

The _Harpas_ are shells of the Indian Ocean, richly enamelled within,
and ornamented externally with slightly oblique longitudinal stripes in
gay colours, with finely-sculptured forms in the intervals; spiral very
small, and opening large. Among the more attractive species are _Harpa
ventricosa_ (Fig. 282), _Harpa imperialis_ (Fig. 283), and _Harpa
articularis_ (Fig. 284).

The fifth family, _Muricidæ_, contains _Fusus_, _Pyrula_, _Triton_, and
_Murex_.

[Illustration: Fig. 282. Harpa ventricosa (Lamarck).]

The _Murex_, or Rock Shells, include a large number of species, all
remarkable for their bright colours and somewhat fantastical and varied
forms. They are found in all seas, but become larger and more branching
in the seas of warm regions. The shell is oval, or rather oblong, the
spire more or less elevated, its surface generally covered with rows of
spines, or tubercular ramifications. The opening, which is oval, is
prolonged in a straight canal, often of very considerable length, as in
Fig. 286 (_Murex haustellum_); the external edge is often smooth or
rippled, the columellar edge sometimes callous.

[Illustration: Fig. 283. Harpa imperialis (Lamarck).]

[Illustration: Fig. 284. Harpa articularis (Lamarck).]

The head of the animal is furnished with two horns or tentacles, ocular
upon their external side, the mouth elongated in the form of a trunk.
The foot is large and round, and furnished with a horny operculum.

[Illustration: Fig. 285. Murex tenuispina (Lamarck).]

[Illustration: Fig. 286. Murex haustellum (Linnæus).]

Among the species with long slender tube, covered with spines, one of
the most notable is _Murex tenuispina_ (Fig. 285), which is a native of
the Indian Ocean and the Moluccas.

Among the strong-tubed species with long canal and no spines, from the
same regions, is _Murex haustellum_ (Fig. 286).

Among the short-tubed species, furnished with foliaceous and jagged
fringes, is _Murex scorpio_ (Fig. 287).

[Illustration: Fig. 287. Murex scorpio (Linnæus).]

[Illustration: Fig. 288. Murex erinaceus (Linnæus).]

One more typical species may be noted, namely, _Murex erinaceus_ (Fig.
288), which is found on all the coasts of Europe, and especially in the
Channel. Other species worthy of notice are found in the Mediterranean
and the Adriatic, some of them, according to Cuvier and de Blainville,
species which furnished the true Tyrian purple of the ancients; but our
space prevents us from dwelling on them.

[Illustration: Fig. 289. Triton variegatum (Lam.).]

[Illustration: Fig. 290. Triton lotorium (Linn.).]

[Illustration: Fig. 291. Triton anus (Lam.).]

The _Tritons_ are ranged beside the genus _Murex_ in the system. Their
shell is irregularly covered with scattered swelling excrescences, not,
as in _Murex_, in longitudinal rows, but scattered all over the surface.
About one hundred species of Triton are known. They inhabit many seas,
but more especially those in warm countries. _Triton variegatum_,
vulgarly called the Marine Trumpet (Fig. 289), is a very large shell,
which even attains a length of sixteen inches; it is enamelled with
great elegance in white, red, and tawny-brown. They come from the Indian
Ocean, where they are very common. _Triton lotorium_ (Fig. 290) is of a
reddish brown externally and white within. The _Triton anus_ (Fig. 291)
is of a whitish colour, spotted with red.

[Illustration: Fig. 292. Fusus proboscidiferus (Lam.).]

[Illustration: Fig. 293. Fusus pagodus (Lesson).]

[Illustration: Fig. 294. Fusus colus.]

The genus _Fusus_, or spindle shells, is distinguished by the elegance
of its form rather than by the brilliancy of its colours. They are
spindle-shaped, spire many-whorled, canal long, operculum egg-shaped.
Among the more remarkable species may be noted _Fusus proboscidiferus_
(Fig. 292), _Fusus pagodus_ (Fig. 293), and _Fusus colus_ (Fig. 294).

The sixth family is _Strombidæ_, of which we give as types,
_Rostellaria_, _Pteroceras_, and _Strombus_. _Strombus_ is a marine
shell, belonging to Equatorial seas, of whose habits and manners very
little is known. It is probable that they are long-lived, for their
shells, when found perfect, have acquired a very considerable thickness
and weight. They are even found encrusted in the interior with numerous
layers of soft earthy sediment, and covered externally with small corals
and other marine productions. _Strombus gigas_ is represented in Figs.
295 and 296.

[Illustration: Fig. 295. Strombus gigas (Linnæus), with the animal.]

Some species of _Strombus_ attain great size, and are placed as
ornaments in halls and dining-rooms. In some of them the opening is
brilliantly shaded, and those are chiefly sought after to decorate
grottoes in gardens, or for collections of shells, where, from their
size, they necessarily occupy a prominent place.

These shells are tun-bellied, terminating at their base by a short
canal, notched or truncated; the right edge gets dilated with age;
simple on one wing, lobed or cuneated in the upper part, and presenting
in its lower part a groove or cavity separated from the canal or from
the notch at the base. But these shells are not merely ornamental, for
some of the streets of Vera Cruz are said to be paved with _Strombus
gigas_.

The animal which inhabits this shell presents a distinct head, provided
with a trunk or snout, and with two tentacles or horns, each bearing a
large and vividly-coloured eye. The foot is compressed and divided into
two portions, the posterior one, which is the longest, bearing a horny
operculum. In the eagle-winged _Strombus_, represented in Figs. 296 and
297, these several peculiarities are well developed. This shell is
large, turbinate, distended in the middle, with an acutely-pointed
spiral studded with conical tubercles, the right edge very broad,
rounded off below. The opening is of a vivid rose purple fading into
white. It is a native of the Antilles.

[Illustration: Fig. 296. Shell of Strombus gigas.]

[Illustration: Fig. 297. Strombus gallus (Linn.).]

[Illustration: Fig. 298. Strombus luhuanus (Linnæus).]

[Illustration: Fig. 299. Strombus cancellatus (Lamarck).]

[Illustration: Fig. 300. Strombus thersites (Gray).]

_Strombus gallus_, or the angel-winged (Fig. 297), veined with stripes
of white and red, comes from the coasts of Asia and America. _Strombus
luhuanus_ (Fig. 298) is fawn-coloured, marked with white, and externally
the right edge is red and striped; inside the columella is shaded purple
and black.

_Strombus cancellatus_, the trellised Strombus (Fig. 299), is small in
size and white in colour. _Strombus thersites_ is also represented (Fig.
300).


PTEROCERAS.

The Pteroceras, from πτερὸν, _wing_, and κέρας, _horn_, in many
respects resemble the Strombi. They are distinguished from them chiefly
in this, that the right edge developes itself with age in long and
slender digital spines more or less numerous, the numbers of which vary
according to the species. The Pteroceræ are found in the seas of both
hemispheres, their vulgar denomination being sea-spiders or scorpions.
A glance at the illustrations (Fig. 301, _Pteroceras scorpio_; Fig.
302, _P. millepeda_; Fig. 303, _P. chiragra_; and Fig. 304, _P.
lambis_) will satisfy the reader as to the general correctness of this
designation.

[Illustration: Fig. 301. Pteroceras Scorpio (Linnæus).]

[Illustration: Fig. 302. Pteroceras millepeda (Linnæus).]

The genus Pteroceras, whose remarkable form is so well calculated to
excite our admiration, has yet another attraction: the colouring of the
shell exhibits many shades, which are particularly varied towards the
opening, where it is generally distinguished by great freshness and
brilliancy, which, added to its other characters, render it the most
interesting of all the Gasteropods.

[Illustration: Fig. 303. Pteroceras chiragra (Linnæus).]

[Illustration: Fig. 304. Pteroceras lambis (Linnæus).]



CHAPTER XV.

MOLLUSCOUS PTEROPODS.

"Natura non facit saltus." LINNÆUS.


The position of the Pteropoda is somewhat unsatisfactory. Their
organization in some respects places them below the level of the
Gasteropods; but yet the general feeling amongst naturalists has been to
assign them a place between the Gasteropods and the most highly
organized of the molluscs, the Cephalopods. The number of genera and
species is less than that of the other great classes of molluscs.

There are three principal Families of Pteropods. First, the _Cliidæ_,
containing Cymodocea, Pelagia, Pneumodermon, and Clio. Second,
_Limacinidæ_, containing Macgillivrayia, Cheletropis, Spirialis, and
Limacina. Third, _Hyaleidæ_, containing Tiedemannia, Cymbulia, Eurybia,
Theca, Cleodora, and Hyalea.

The principal characteristic of the Pteropoda is a membranous expansion
situated on the right and left side of their head, from which they take
their name of Pteropoda, from ποῦς-πτερὸς, winged feet.

The wings or flappers with which they are provided enable them to pass
rapidly through the water, reminding us strongly of the movements of a
butterfly, or other winged insect, and like them, their motions are long
continued. They advance in this manner in a given direction, while the
body or the shell remains in an oblique or vertical position.

These little molluscs may be seen to ascend to the surface very
suddenly, turn themselves in a determinate space, or rather swim,
without appearing to change their place while sustaining themselves at
the same height. If anything alarms them they fold up their flappers,
and descend to such a depth in their watery world as will give them the
security they seek. They thus pass their lives in the open sea far from
any other shelter, except that yielded by the gulf weed and other algæ.
In appearance and habits, these small and sometimes microscopic
creatures resemble the fry of some other forms of mollusca. They
literally swarm both in Tropical and Arctic seas; sometimes so numerous
as to colour the ocean for leagues. They are the principal food of
whales and sea-birds in high latitudes, rarely approaching the coast.
Only one or two species have been accidentally taken on our shores, and
those evidently driven thither by currents into which they have been
entangled, or by tempests which have stirred the waters with a power
beyond theirs. Dr. Leach states that in 1811, during a tour to the
Orkneys, he observed on the rocks of the Isle of Staffa several
mutilated specimens of _Clio borealis_. Some days after, having borrowed
a large shrimp-net, and rowing along the coast of Mull, when the sea,
which had previously been extremely stormy, had become calm, he
succeeded in catching one alive, which is now in the British Museum.

"In structure," Mr. Huxley tells us, "the Pteropods are most nearly
related to the marine univalves, but much inferior to them. Their
numerous ganglia are concentrated into a mass below the œsophagus; they
have auditory vesicles containing otolithes, and are sensible of light
and heat, and probably of odours, although at most they possess very
imperfect eyes and tentacles. The true foot is small or obsolete; in
_Cleodora lanceolata_ (Fig. 309) it is combined with the fins; but in
_Clio_ it is sufficiently distinct, and consists of two elements or
_spirals_; the superior portion of the foot supports an operculum. The
fins are developed from the sides of the mouth or neck, and are the
equivalents of the side-lappets (_Epipoda_) of the sea-snails. The mouth
of _Pneumodermon_ is furnished with two supporting miniature suckers;
these organs have been compared to the dorsal arms of the cuttle-fishes;
but it is doubtful whether their nature is the same. A more certain
point of resemblance is the ventral flexure of the alimentary canal,
which terminates on the under surface near the right side of the neck.
The Pteropods have a muscular gizzard armed with gastric teeth, a liver,
a pyloric cæcum, and a contractile renal organ opening into the cavity
of the mantle. The heart consists of an auricle and a ventricle, and is
essentially opisthobranchiatic, although sometimes affected by the
general flexure of the body. The venous system is extremely incomplete.
The respiratory organ, which is little more than a ciliated surface, is
either situated at the extremity of the body, and unprotected by a
mantle, or included in a branchial chamber with an opening in front. The
shell when present is symmetrical, glassy, and translucent, consisting
of a dorsal and a ventral plate united, with an anterior opening for the
head, lateral slits for long filiform processes of the mantle, and
terminated behind in one or three points; in other cases it is conical
or spirally-coiled, and closed by a spiral operculum. The sexes are
united, and the orifices situated on the right side of the neck.
According to Vogt, the embryo Pteropod has deciduous vola like the
sea-snails, before the proper locomotive organs are developed."

[Illustration: Figs. 305 and 306. Hyalea gibbosa (Rang.).]

[Illustration: Figs. 307 and 308. Hyalea longirostris (Lesueur).]

The Pteropods seem to be eminently sociable and gregarious, swarming
together in great numbers; they present some analogical resemblances to
the Cephalopodæ; but permanently they represent the larval stage of the
sea-snails. De Blainville divides the group into two sections,
_Thecosomata_ and _Gymnosomata_, the first including the _Hyaleidæ_ and
_Limacinidæ_; the second contains one family, the _Cliidæ_. The Hyaleidæ
have small horny shells, very thin and transparent, globulous, or
elongated, open anteriorly, cloven on the sides, and truncate at the
posterior extremity. Their globular body is formed of two parts, the one
including the head, bearing two very strong tentacles, and two large
fins or flappers in the form of wings, springing from each side of the
mouth.

These molluscs are small, and generally of a yellowish-blue or violet
colour. They are inhabitants of the deep sea, and rarely seen out of
what sailors call "blue water." They plough the waves with great
rapidity by the aid of their powerful fins. Certain winds throw them
sometimes in great numbers on the shores of the Mediterranean. These
little creatures, so inoffensive, and which live together in vast
numbers, seem to be an easy and ready-prepared prey, which the great
marine animals may swallow by thousands. Twenty species of _Hyalea_ are
described as actually living in the Atlantic and Australian seas. Of
these _Hyalea gibbosa_ (Figs. 305, 306) and _Hyalea longirostris_ (Figs.
307, 308) are here represented.

[Illustration: Fig. 309. Cleodora lanceolata (Lesueur).]

[Illustration: Fig. 310. Cleodora compressa (Eydoux and Souleyet).]

The great flappers of _Hyalea tridentata_ are yellow, marked at their
base with a fine violet spot. Its shell, plain above, convex beneath, is
cloven on the side. The superior part is longer than the inferior, and
the transverse line which unites them is furnished with three teeth.
This shell is yellow, and nearly translucent. When the animal swims, two
expansions of its mantle issue from the lateral clefts in the shell.

_Cleodora lanceolata_ is a delicate and graceful creature; its body, of
gelatinous appearance, has a distinct head, with its fins near the neck,
notched in the form of a heart (Fig. 309); its posterior part is
globulous, transparent, and luminous even in the dark. The animal which
inhabits it sometimes shines through the shell like a light placed
inside a lantern. This shell is triangular, as in _Cleodora cuspidata_
(Fig. 311), thin, vitreous, and fragile, terminating in a long spine at
the base.

[Illustration: Fig. 311. Cleodora cuspidata (Bucc.)]



CHAPTER XVI.

CEPHALOPODOUS MOLLUSCA.

"Monstrum horrendum, informe, ingens." VIRGIL.


The highest class of Molluscs is the Cephalopoda, which has been divided
by Professor Owen into two Orders, _Tetrabranchiata_, or animals having
four branchiæ, and the _Dibranchiata_, having two branchiæ. The first
Family of the _Tetrabranchiata_, having the Ammonitidæ, contains the
fossil Turrilites and Ammonites. The second Family, _Orthoceratidæ_,
contains the fossil Gomphoceras and Orthoceras. The third Family,
_Nautilidæ_, contains Nautilus.

The name Cephalopoda, as already stated, is taken from the position of
the feet, which are inserted in the anterior part of the head: in Greek
κεφαλὴ, _head_, and ποῦς-ποδὸς, _foot_.

The Cephalopodous Molluscs are indeed highly organised for Molluscs, for
they possess in a high degree the sense of sight, hearing, and touch.
They appear with the earlier animals which present themselves on the
earth, and they are numerous even now, although they are far from
playing the important part assigned to them in the early ages of organic
life upon our planet. The _Ammonites_ and _Belemnites_ existed by
thousands among the beings which peopled the seas during the secondary
epoch in the history of the globe.

This great class is otherwise divided into two orders: _Tentaculiferous
Cephalopods_, those furnished with strong fleshy tentacula, and
_Acetabuliferous_, or sucker-bearing.


TENTACULIFEROUS CEPHALOPODS.

In place of bearing simple suckers (_Acetabula_), like the last order of
Cephalopods, this group is furnished with true organs of prehension, or
tentacles. They differ from the first group chiefly in their more
numerous arms, which are quite tentaculiferous, having neither suckers
nor capsules, and by having an external shell. The number of living
species is extremely limited; for this group of animals belongs
peculiarly to the earlier ages of our globe, is gradually becoming
extinct, and presents in our days only some rarer species, when we
compare them with the prodigious numbers of these beings which animated
the seas of the ancient world. In fact, the only living type of the
order is the nautilus, which has a singular resemblance in form to the
argonaut.

The shell of this mollusc has a regularly convoluted form, the last
whorl being equal to all the others. It is divided internally into
numerous cells, formed by transverse partitions, concave in front and
perforated towards the centre, and forming a kind of funnel, which gives
passage to a respiratory siphon.

In the last cell of the shell (Fig. 312) is the animal, covered by its
mantle, which covers the walls of the cells. When it contracts itself it
is protected by a sort of triangular and fleshy hood. Numerous
contractile tentacles, re-entering into the sheath, some of them
furnished with numerous lamellæ, surround the head, which is, besides,
scarcely distinguished from the body. The head bears two great
projecting eyes, planted upon a peduncle.

[Illustration: Fig. 312. Nautilus pompilius (Linnæus), showing the
interior of the lower cell, to which the animal is fixed.]

Like Sepia and Octopus, the mouth of the Nautilidæ is armed with
mandibles, fashioned like the parrot's beak; the branchiæ are four in
number. The circulating system consists of a ventricle and auricle, and
the locomotive tube is protected in its whole length. The shell is
secreted by the outer edge of the mantle, while its posterior extremity
fashions the walls of the cells, which indicate the successive growth of
the individual.

The siphon, which traverses all the chambers, receives and protects the
ligament, by the aid of which the Cephalopod is retained in the last
chamber of the shell.

Fig. 313 is the same section, with the last cell empty, and with the
perforations through which the siphon passes.

The Nautilidæ are inhabitants of the Indian Ocean and the sea round the
Molucca Islands. In swimming, their head and tentacles are projected
from out of the shell. In walking on rocks they drag themselves along
the ground, the body upwards, the head and tentacles beneath. They
betake themselves frequently to miry cavities frequented by fish. It is
a much more common occurrence to find the empty than inhabited shells of
the Nautilus at sea. This, probably, arises from its exposure to the
attacks of crustaceans and other marine carnivora. This seems to be
proved by the mangled appearance of the edges in the empty shells thus
met with.

[Illustration: Fig. 313. Nautilus pompilius (Linnæus) showing the lower
cell and the partition giving passage to the siphon.]

[Illustration: Fig. 314. Shell of Nautilus pompilius (Linnæus).]

The Pearly Nautilus, _Nautilus pompilius_ (Fig. 314), is so common on
the Nicobar coast that the inhabitants salt and dry its flesh, and store
them as provisions. Its shell attains about eight inches in its greatest
height. This shell is still used by the Hindoo priests as their conch or
shell, with which they summon their devotees to worship. It is nearly
round, smooth, transversely blazed in its posterior part, and entirely
white anteriorly. A very fine nacre is yielded by this mollusc, which is
much used in ornamental cabinet-work. The Orientals make drinking-cups,
on which they engrave designs and figures, which form graceful objects.
Similar vases were formerly shaped in Europe, which found their way into
great houses. In our days they are generally consigned to cabinets of
curiosities and the shops of dealers in articles of virtù.

Owen's second order, _Dibranchiata_, contains six families; the first is
_Spirulidæ_, containing the curious Spirula, that little gem amongst
oceanic shells. The second family is _Sepiadæ_, containing Belemnosis
and Sepia. The third is _Belemnitidæ_; the fourth, _Teuthidæ_; the
fifth, _Octopodidæ_; and the sixth, _Argonautidæ_.


ACETABULIFEROUS CEPHALOPODA.

To this group belong the cuttle-fish, squids, and argonauts, among
existing species, and the Belemnites among the fossil species. Some of
these creatures are large, and essentially flesh-eaters, or carnivorous;
and, if we may believe all that has been written respecting them, very
formidable ones. Listen to Michelet, while he paints the warlike humour
of these inhabitants of the deep:--"The Medusæ and Molluscs," says this
popular author, "are generally innocent creatures, and I have lived with
them in a world of gentle peace. Few flesh-eaters among them; those even
which are so, only kill to satisfy their wants, living for the most part
on life just commenced--on gelatinous animals, which can scarcely be
called organic. From this world grief was absent. No cruelty and no
passion. Their little souls, if mild, were not without their ray of
aspiration towards the light, and towards what comes to us from heaven,
and towards that love, revelling in that changing flame which at night
is the light of the deep. It is now, however, necessary to describe a
much graver world: a world of rapine and of murder; from the very
beginning, from the first appearance of life, violent death appeared;
sudden refinement, useful but cruel, purification, of all which has
languished, or which may linger or languish, of the slow and feeble
creation whose fecundity had encumbered the globe.

"In the more ancient formations of the old world we find two
murderers--a nipper and a sucker. The first is revealed to us by the
imprint of the trilobite, an order now lost, the most destructive of
extinct beings. The second subsists in one gigantic fragment, a beak
nearly two feet in length, which was that of a great sucker or
cuttle-fish (_Sepia_). If we may judge from such a beak, this monster,
if the other parts of the body are in proportion, must have been
enormous; its ventose, invincible arms, of perhaps twenty or thirty
feet, like those of some monstrous spider. The sucker of the world, soft
and gelatinous! it is himself. In making war on the molluscs he remains
mollusc also; that is to say, always an embryo. He presents the strange,
almost ridiculous, if it was not also terrible, appearance of an embryo
going to war; of a foetus furious and cruel, soft and transparent, but
tenacious, breathing with a murderous breath, for it is not for food
alone that it makes war: it has the wish to destroy. Satiated, and even
bursting, it still destroys. Without defensive armour, under its
threatening murmurs there is no peace; its safety is to attack. It
regards all creatures as a possible enemy. It throws about its long
arms, or rather thongs, armed with suckers, at random." Such is the
somewhat exaggerated picture which the eloquent historian and poet draws
of the Molluscous Cephalopod, and it must be admitted that there is a
basis of truth in this, as well as in the more recent one painted by
Victor Hugo, in his eloquent book, "Les Travailleurs de la Mer." Where,
however, there is so much of the fictitious floating about, it will be
our endeavour to eliminate facts only.


FAMILY OF THE SEPIADÆ.

The body of the cuttle-fish (_Sepia_) is thus a very singular structure,
somewhat reminding us of certain species of polyps. We find a body or
abdominal mass, hand ahead, separated by compression, sufficiently
marked. The body is covered by the mantle, which has the form of a sac
opened only in front by a transverse cleft. The head has a projecting
and well-developed eye on each side; it is surmounted by a sort of
fleshy funnel, which is divided by four pairs of tentacles. At the
bottom of this tentacular funnel is the mouth; and from the anterior
opening in the mantle a tube issues, which is wide at its base.

The Sepiadæ have eight arms rising from the crown of the head armed with
four rows of suckers, two long slender tentacles with broadly-expanding
ends, and stalked suckers; eyes moving in their sockets, and body
broadly ovate in Sepia.

If we study the general aspect of the animal more closely, we find that
the tentacles--which serve at once as organs of locomotion for swimming,
for creeping, and as prehensile organs for seizing and retaining its
prey--are conical, very long, and all of the same form. Each of them has
towards its axis a longitudinal canal, which encloses a great nerve,
which is also surrounded with muscular fibres, arranged in rays. The
suckers, already described, occupy all the internal surface of the eight
tentacular arms, which are arranged in two rows, having the form very
nearly of a semi-spherical capsule. Of these suckers, each arm of the
cuttle-fish carries about two hundred and forty, the total number being
nearly a thousand. The mouth we have already described, in Dr. Roget's
words: "The teeth move vertically, much as the cutting edge of the two
blades of a pair of scissors move upon each other, tearing the prey by
the assistance of their hooked terminations."

The tongue is covered on its upper part by a thick horny bed, bristling
in the centre with a series of recurving teeth, while its edge is armed
with three other erect teeth, which are slender and hooked. The
oesophagus is long and slender. At the abdomen the gullet expands into a
sort of frill, to which succeeds a gizzard, with strong fleshy walls;
and, finally, a very short intestine, which directs itself forward,
terminating on the median line of the body. Towards the anterior parts
is a cavity, of which a few words must be said. It occupies the free
space comprised between the exterior surface of the abdomen and the
internal face of the mantle; and here the respiratory organs, namely,
the _branchiæ_, are lodged. Here, also, are the reproductive and
excretory organs.

The branchiæ, which are two in number, are voluminous, but short,
tufted, and leaf-like. The branchial cavity can dilate and contract
itself alternately. It communicates externally by two openings: the one,
fashioned into a cleft, receives, while the other, which is prolonged
into a tube, serves to eject, the water, and becomes a powerful organ of
locomotion.

The inspiration of the animal is thus made by a cleft in the mantle, and
expiration by the tube: the renewal of the respirable liquid acts as a
sort of sucking and forcing pump, at the surface of the lamellar
branchials. The cuttle-fish, in short, will be at no loss to reply to
the question of the Don Diego of Corneille--

    "Rodrique, as-tu du cœur?"

for they have three hearts. The two first are placed at the end of the
branchiæ. With each beat of the pulse the venous blood is brought from
all parts of the body, and propelled through each gill or branchiæ.
Vivified by respiration in the internal tissue of the branchiæ, it is
carried by the veins into the third heart, situated upon the median line
of the body; and now the regenerated fluid is again distributed
throughout the rest of the economy.

Not to oppress the reader with anatomical details, we shall just remark
that the gaze of the cuttle-fish is decided and threatening. Its
projecting eyes and golden-coloured iris are said to have something of
fascination in them. The animal seems able even to economise the power
of its glance, being able to cover its eyes from time to time by
contracting the skin which surrounds them, and bringing the two
translucent eyelids with which it is furnished closer together.

The cuttle-fishes are essentially aquatic and marine animals. We find
them in every sea in all parts of the world; but they are most
formidable in warm countries. They have a great predilection for the
shore. During their youth they associate in flocks; but with age they
fly from association, and retire into the clefts and hollows of the
rocks. The old cuttle-fish is only found in rugged and rocky places,
bristling with naked, pointed rocks, which have been worn by the waves,
but generally in places only a few feet below the level of low water.
"How often," says D'Orbigny, "have we not observed the cuttle-fish in
his favourite retirement! There, with one of his arms cramped to the
walls of its dwelling, it extends the other towards the animals which
pass at its gate, embraces them, and by its power renders useless all
their efforts to disengage themselves."

If we observe a cuttle-fish when it is what may be called walking,
either on land or at the bottom of the sea, it will be seen to walk on
one side, its head downwards, its mouth touching the ground, the arms
extended and grappling some supporting object, and drawing the body
forward; at the same time the arms at the opposite side are contracted
and folded up, so as to assist by a contrary movement. On shore the
movement of these animals is very slow. On the other hand, they swim
very rapidly, assisted by all their arms, and aided by the water ejected
from the locomotive tube, their movement being most frequently
backwards, the body first, the six superior arms placed horizontally,
the two others brought together above: the first help to sustain them in
their horizontal position, the last to guide them, inclining to the
right or left as the animal changes its direction.

The cuttle-fishes feed on crustaceans, fishes, and also on shelled
molluscs--every kind of animal, in fact, which comes within their reach;
so that it is readily taken by means of the flesh of fish or
crustaceans, in which a strong hook is concealed. They live for five or
six years, and reproduce by eggs, which are large, and generally found
in clusters, known to fishermen under the name of _sea-grapes_.

Like the zoophytes, they possess the property of redintegration, already
described, being able to reproduce any arm that may be destroyed. There
is another singular peculiarity which the cuttle-fish shares with man.
Under the influence of strong emotion the human face becomes pale, or
blushes, and in some individuals it is said to become blue. This has
always been supposed to be an attribute of humanity; but the cuttle-fish
shares it with our race. Yielding to the impressions of the moment, the
cuttle-fish suddenly changes colour, and, passing through various tints,
it only resumes its familiar one when the cause of the change has
disappeared. They are, in fact, gifted with great sensibility, which
reacts immediately upon their tissues, these being extremely elastic and
delicate. Sudden changes of colour are produced--changes which far
exceed the same phenomena in man. Under the influence of passion or
emotion man is born to blush, but under no sort of excitement does he
cover himself with pustules; this the cuttle-fish does: it not only
changes colour, but it covers itself with little warts. "Observe a
cuttle in a pool of water," says D'Orbigny, "as it walks round its
retreat--it is smooth, and of very pale colour. Attempt to seize it, and
it quickly assumes a deeper tint, and its body becomes covered on the
instant with warts and hairs, which remain there until its confidence is
entirely restored."

The following fact is abbreviated from the "Natural History and Fishery
of the Sperm Whale." Mr. Beale had been searching for shells among the
rocks in Bonin Island, and was much astonished to see at his feet a most
extraordinary-looking animal, crawling back towards the surf which it
had just left. It was creeping on its eight legs, which, from their soft
and flexible nature, bent considerably under the weight of its body, so
that it was just lifted by an effort above the rocks. It appeared much
alarmed, and made every attempt to escape. Mr. Beale endeavoured to
stop it by putting his foot on one of its tentacles, but it liberated
itself several times in spite of all his efforts. He then laid hold of
one of the tentacles with his hand, and held it firmly, and the limb
appeared as if it would be torn asunder in the struggle. To terminate
the contest, he gave it a powerful jerk; it resisted the effort
successfully, but the moment after the enraged animal lifted a head with
large projecting eyes, and loosing its hold of the rocks, suddenly
sprang upon Mr. Beale's arm, which had been previously bared to the
shoulder, and clung to it with its suckers, while it endeavoured to get
the beak, which he could now see, between the tentacles, in a position
to bite him. Mr. Beale describes its cold slimy grasp as extremely
sickening, and he loudly called to the captain, who was also searching
for shells, to come to his assistance. They hastened to the boat, and he
was released by killing his tormentor with a boat-knife, when the arms
were disengaged bit by bit. Mr. Beale states that this Cephalopod must
have measured across its expanded arms about four feet, while its body
was not bigger than a large hand clenched. It was the species called the
rock-squid by whalers.

These formidable and curious Cephalopods, the Μαλάκια of Aristotle,
_Mollia_ of Pliny, and _Cephalophora_ of De Blainville, have the mantle,
according to Cuvier, united beneath the body, thus forming a muscular
sac which envelopes the whole viscera. The body is soft and fleshy,
varying much in form, being sub-spherical, sub-elliptical, and
cylindrical, the sides of the mantle in many species extending into
fleshy fins. The head protrudes from the muscular sac, and is distinct
from the body; it is gifted with all the usual senses, the eyes in
particular, which are either pedunculate or sessile, being large and
well developed. The mouth is anterior and terminal, armed with a pair of
horny or calcareous mandibles, which bear a strong resemblance to the
bill of a parrot, acting transversely, one upon the other. Its position
is the bottom of a sub-conical cavity, forming the base of numerous
fleshy tentacular appendages which surround it, and which are termed
arms by some writers. These appendages in the great majority of living
species are provided with suckers, _acetabula_ (cupping-glass-like
appendages), by means of which the animal moves at the bottom of the
sea, head downwards, or attaches itself to its prey. These suckers are
armed or unarmed with a long, sharp, horny claw. In the unarmed
acetabulum, the mechanism for adhesion is well described by Dr. Roget:
"The circumference of the disk," says this writer, "is raised by a soft
and turned margin; a series of long slender folds of membrane covering
corresponding fascicula of muscular fibre converge from the
circumference towards the centre of the sucker, at a short distance from
which they leave a circular aperture; this opens into a cavity which
widens as it descends, and contains a cone of soft substance rising from
the bottom of the cavity, like the piston of a syringe. When the sucker
is applied to the surface, for the purpose of adhesion, the piston,
having previously been raised so as to fill the cavity, is retracted,
and a vacuum produced, which may be still further increased by the
retraction of the plicated portion of the disk." Here we have an
excellent description of the apparatus for holding on. When the animal
is disposed to let go his hold, according to Professor Owen, "the
muscular arrangement enables the animal to push forward the piston, and
thus in a moment destroy the vacuum which retraction had produced."

In the case of the armed Cephalopods (_Onychoteuthis_), Professor Owen
remarks, "that there are circumstances in which even the remarkable
apparatus described by Dr. Roget would be insufficient to fulfil the
offices in the economy of Nature for which the Cephalopod was created,
and that in species which have to contend with the agile mucous-clad
fishes more powerful organs of prehension are superadded to the suckers,
so that in the calamary the base of the piston is, he remarks, enclosed
in a horny hoop, the outer and anterior margin of which is developed
into a series of sharp curved teeth, which can be firmly pressed into
the flesh of a struggling prey by the contraction of the surrounding
transverse fibres, and can be withdrawn by the action of the retracting
fibres of the piston. "Let the reader," the professor adds, "picture to
himself the projecting weapon of the horny hoop developed into a long,
curved, sharp-pointed claw, and these weapons clustered at the expanded
terminations of the tentacles, and arranged in a double alternate series
along the internal surface of the eight muscular feet, and he will have
some idea of the formidable nature of the carnivorous cephalopod." The
professor notices another structure which adds greatly to the prehensile
powers of the uncinated Cephalopods. "At the extremities of the long
tentacles a cluster of small, simple, unarmed suckers may be observed at
the base of the expanded part. When these latter suckers are applied to
one another, the tentacles are firmly locked together at that part, and
the united strength of both the elongated peduncles can be applied to
drag towards the mouth any resisting object which has been grappled by
the terminal hooks. There is no mechanical contrivance which surpasses
this structure; art has remotely imitated it in the fabrication of the
obstetrical forceps, in which either blade can be used separately, or,
by the interlocking of a temporary blade, be made to act in
combination."--_Cyc. of Anat._

The third Family, _Belemnitidæ_, contains Belemnitella and Belemnites,
and other genera of less importance; they are all now extinct, although
once numerous as species.

The cuttles, _Sepia_ (Fig. 315), have the body fleshy and depressed,
continued into a sac, and bordered on all its length on both sides with
a wing or narrow fin, the larger short and flat, broader than it is
long, with two large eyes, covered by an expansion of the skin, which
becomes transparent over a surface equal to the diameter of the iris,
and furnished with inferior contractile eyelids.

[Illustration: Fig. 315. Sepia officinalis (Linnæus).]

This head is surmounted by ten tentacular arms or feet, eight of which
are short and conical, and two long and slender, terminating in a sort
of spatula. These arms are all armed with suckers, and are perfectly
retractile. They surround a mouth armed with two horny jaws not unlike
the beak of a parrot.

The skin of the cuttle-fish presents in one vast hollow, occupying all
the extent of the back, a great calcareous part, the form and structure
of which is quite characteristic of this genus. It is known as the
cuttle-bone (Fig. 316). This bone is used for many purposes; among
others, it is used in a powdered state as a dentifrice. It is sometimes
suspended in the cage with captive birds, that they may whet their beaks
on it, and collect phosphate of lime for the formation and repair of
their bones. The osselet is oval or oblong, some provided with a
slightly salient point. The upper part is surrounded with a horny or
cretaceous margin, and presents in the centre a combination of spongy
cells.

Most of the Cephalopods secrete a blackish, inky fluid, to which some
allusion has been made, but the uses of which, in the economy of the
animals, is imperfectly known. The cuttles have considerable quantities
of this liquor, which is contained in a sort of sac or ink-purse, placed
low down in the abdomen. When the animal is pursued or threatened with
danger it discharges a jet of the fluid, which renders the water thick
and muddy, and permits it to escape in the obscurity from its pursuers.
It appears that the cuttle-fish avails itself of this stratagem when
left accidentally ashore. It is related of an English officer, that,
having dressed for dinner, and having some time to spare, he proceeded
along the shore on his favourite search for objects of natural history.
He reached a hollow rock in which a cuttle-fish had established its
quarters; he soon detected the animal, which looked at him for some time
with its great prominent eyes; in short, they watched each other with
fixed attention. This mute contemplation came to a sudden and unexpected
termination by the discharge of a voluminous jet of inky fluid, which
covered the officer, which was the more unfortunate, since he was in his
summer dress of white trousers.

[Illustration: Fig. 316. Internal bone of Sepia officinalis.]

[Illustration: Fig. 317. Sepia tuberculosa (Lamarck).]

The ink of the cuttle-fish is a favourite pigment, used in water-colour
painting under the name of _sepia_. It is truly indestructible; and the
hard and black substance found in the sac of fossil species of
cuttle-fish when diluted with water produces a brilliant sepia. This
property of the inky fluid was well known to the Romans, who used it in
making ink. It was long supposed to be the chief ingredient in China
ink; but a recent traveller, Mr. Seebold, who has visited the
manufactory, and investigated the subject, has revealed the true process
by which it is prepared.

The cuttle-fish affects the sea-shore; they are along-shore molluscs.
The flattened form of their bodies is favourable to a coasting life, by
permitting them to rest easily on the bottom. Still they do not remain
all the year round upon the coast. The cold in temperate regions, and
the opposite reason in warm regions, leads them to withdraw from the
shore, to which they only return in the spring. They are rarely seen in
the Channel in winter, but with the vernal sun they appear in large
shoals. What is the mechanism by which these animals are moved? When the
cuttle-fish wishes to swim rapidly and backwards, they advance in the
water by means of the locomotive tube, sending back the ambient liquid.
When they wish to approach a prey slowly in order to seize it, they swim
by the aid of their fins and arms. In order to swim backwards, they
contract the arms provided with tentacles, and spread out horizontally
the arms without tentacles.

The cuttles are flesh-eaters, and tolerably voracious. They feed
themselves upon fishes, molluscs, and crustaceans. They are true aquatic
brigands, who kill not to feed themselves, but for the sake of killing;
and Nature, by a just equilibrium, applies to them the _lex talionis_.
They fall victims, in their turn, to the vengeful jaws of the porpoises
and dolphins. Such is the terrible law of Nature: some must die that
others may live. Michelet gives us a glimpse of the manner in which the
dolphins dispose of the cuttle-fish in his "Livre de la Mer." "These
lords of the ocean," he says, "are so delicate in their tastes that they
eat only the head and arms, which are both tender and of easy digestion.
They reject the hard parts, and especially the after-part of the body.
The coast at Royan, for example, is covered with thousands of these
mutilated cuttle-fish. The porpoises take most incredible bounds, at
first to frighten them, and afterwards to run them down; in short, after
their feast, they give themselves up to gymnastics."

In the spring the cuttle-fishes deposit their eggs, but without
abandoning them. On the contrary, they exhibit a truly maternal care,
taking much trouble to attach them to some submarine body, in which
position the temperature of the water serves to hatch the eggs. _Sepia
officinalis_, for example, chooses, at the moment of laying, a stem of
_Fucus_, a foot of _Gorgonia_, or some other solid submarine body not
less in dimensions than the little finger, and there it firmly attaches
its eggs, which are pear-shaped, that is, pointed at one extremity,
while a long _lanière_ of a gelatinous nature, flat and black in
appearance, with which they are provided, surrounds the solid body like
a ring. Each female lays and attaches in this manner from twenty to
thirty eggs, which are clustered together somewhat like a bunch of fine
black grapes (Fig. 318). About a month after this the eggs are hatched.

The colours of _Sepia officinalis_ vary considerably; but in general it
may be remarked that the males are ornamented with deeper colours than
the females. Transverse bands of a blackish brown furrow their backs,
and diminish their breadth. Outside of these bands are small spots of a
vivid white: very near the edge there is a white border, accompanied
inside with a second edging of a beautiful violet. The median and
anterior parts of the body are spotted here and there; beneath, a
whitish tint with reddish speckles prevails.

[Illustration: Fig. 318. Sepia officinalis (Linnæus).]

The cuttle-fishes are found on every shore, and wherever they are found
they are eaten, for their flesh is savoury. They are usually fried or
boiled. They form an excellent bait for large ground-fish, such as
dog-fish, rays, and congers, which are fond of their flesh.

Thirty species are known, and they are chiefly characterised by the
arrangement and form of the cupules of the arms. _Sepia officinalis_ is
common on the shores of the ocean from Sweden to the Canaries, and in
all parts of the Mediterranean.

The fourth family, _Teuthidæ_, contains _Loligopsis_, _Cranchia_, and
_Loligo_.

The _Calmars_ were described by Aristotle under the name of Γείφις,
and by Pliny under that of _Loligo_, which is still retained as the
generic name. Their popular name of Calmar (calamar in old French) is
taken from their resemblance to certain species of ink-holders. Oppian,
who endowed the argonaut with wings, believed that the calmar also
could take to the air, in order to avoid his enemies. Nevertheless,
he was much puzzled how to give the form and functions of a bird to a
fish. Themistocles, by way of insult to the Eretrians, likened them
to calmars, saying they had swords and no hearts. Athenæus, a Greek
physician before Galen, dwelt upon the nourishing properties of the
flesh of the calmar.

Common enough in temperate regions, the calmars abound in the seas of
the Torrid zone: they are gregarious, and live in numerous shoals, their
bands taking every year the same direction, their emigration proceeding
from temperate to warm regions--nearly the same course as that followed
by the herrings and pilchards.

The calmars, like the cuttles, propel themselves backwards through the
water with great velocity, driving back the water by means of their
locomotive tube, moving with such vigour and promptitude that they have
been known to throw themselves out of the water, falling on the shore or
on the deck of a vessel. They only appear momentarily on the shore, and
only sojourn there to deposit their eggs, which are gelatinous in
substance, about the level of the lowest tides. The body in the calmars
is longer than in the cuttle-fish, cylindrical in shape, and terminating
in a point, having two lateral fins, which occupy the lower half or
third of its body.

[Illustration: Fig. 319. Loligo vulgaris, with its pen, or internal bone
(Lamarck).]

[Illustration: Fig. 320. Loligo Gahi (D'Orbigny).]

In the common calmar, _Loligo vulgaris_ (Fig. 319), and the _Loligo_
_Gahi_ (Fig. 320), we have two extreme forms represented, both taken
from the magnificent work of MM. D'Orbigny and Ferussac, on the
_Cephalopodes acetabulifores_. These molluscs are whitish-blue and
transparent, covered with spots of bright red. The osselet is
lanceolate--that of the male elongated and somewhat resembling a
feather, that of the female much broader and more obtuse. Their head is
short, furnished with two large projecting eyes; the mouth is surrounded
with ten arms, provided with suckers, two of these being much longer
than the others, having peduncles or foot-stalks.

The internal bone of the calmar differs much from that of the cuttles;
it is thin, horny, transparent, and somewhat resembling a feather, from
a portion of which the _barbs_ have been removed. Their food consists
chiefly of small fishes and molluscs. With the greater fishes and
cetaceæ they carry on constant war. They are caught and used for various
purposes; along the coast they are eaten; the fishermen use them as
bait, especially in fishing for cod.

It is no easy task to separate the real from the fabulous history of the
Cephalopods. Aristotle and Pliny have alike assisted, by their
marvellous relations, to throw that halo of wonder round it which the
light of modern science has not altogether dispelled. Pliny the Ancient
relates the history of an enormous cuttle-fish which haunted the coast
of Spain, and destroyed the fishing-grounds. He adds that this gigantic
creature was finally taken, that its body weighed seven hundred pounds,
and that its arms were ten yards in length. Its head came by right to
Lucullus, to whose gastronomical privileges be all honour. It was so
large, says Pliny, that it filled fifteen amphoræ, and weighed seven
hundred pounds also.

Some naturalists of the Renaissance, such as Olaüs Magnus and Denis de
Montfort, gave credit--which they are scarcely justified in doing--to
the assertions of certain writers of the north of Europe, who believed
seriously in the existence of a sea-monster of prodigious size which
haunted the northern seas. This monster has received the name of the
_Kraken_. The Kraken was long the terror of these seas; it arrested
ships in spite of the action of the wind, sails, and oars, often causing
them to founder at sea, while the cause of shipwreck remained
unsuspected. Denis de Montfort gives a description and representation of
this Kraken, which he calls the Colossal Poulpe, in which the creature
is made to embrace a three-masted ship in its vast arms. Delighted with
the success which his representation met with, Denis laughed at the
credulity of his contemporaries. "If my Kraken takes with them," he
said, "I shall make it extend its arms to both shores of the Straits of
Gibraltar." To another learned friend he said, "If my entangled ship is
accepted, I shall make my Poulpe overthrow a whole fleet."

Among those who admitted the facetious history of the Kraken without a
smile, there was at least one holy bishop, who was, moreover, something
of a naturalist. Pontoppidan, Bishop of Bergen, in Norway, in one of his
books assures us that a whole regiment of soldiers could easily
manœuvre on the back of the Kraken, which he compares to a floating
island. "Similior insulæ quan bestiæ," wrote the good Bishop of Bergen.

In the first edition of his "System of Nature," Linnæus himself admits
the existence of this colossus of the seas, which he calls _Sepias
microcosmos_. Better informed in the following edition, he erased the
Kraken from his catalogue.

The statements of Pliny respecting the Colossal Poulpe, like those of
Montfort about the Kraken, are evidently fabulous. It is, however, an
undisputed fact that there exists in the Mediterranean and other seas
cuttle-fish--a congenerous animal--of considerable size. A calmar has
been caught in our own time, near Nice, which weighed upwards of thirty
pounds. In the same neighbourhood some fishermen caught, twenty years
ago, an individual of the same genus nearly six feet long, which is
preserved in the Museum of Natural History at Montpellier. Péron, the
naturalist, met in the Australian seas a cuttle-fish nearly eight feet
long. The travellers Quoy and Gaimard picked up in the Atlantic Ocean,
near the Equator, the skeleton of a monstrous mollusc, which, according
to their calculations, must have weighed two hundred pounds. M. Rung
met, in the middle of the ocean, a mollusc with short arms, and of a
reddish colour, the body of which, according to this naturalist, was as
large as a tun cask. One of the mandibles of this creature, still
preserved in the Museum of the College of Surgeons, is larger than a
hand.

In 1853 a gigantic cephalopod was stranded on the coast of Jutland. The
body of this monster, which was dismembered by the fishermen, furnished
many wheelbarrow loads, its pharynx, or back part of the mouth, alone
being as large as the head of an infant. Dr. Steenstrup, of Copenhagen,
who published a description of this creature under the name of
_Architeuthis dux_, shows a portion of the arm of another cephalopod,
which is as large as the thigh-bone of a man. But a well-authenticated
fact connected with these gigantic cephalopods is related by Lieutenant
Bayer, of the French corvette Alecton, and M. Sabin Berthelot, French
Consul at the Canary Islands, by whom the report is made to the Académie
des Sciences.

The steam-corvette Alecton was between Teneriffe and Madeira when she
fell in with a gigantic calamary, not less--according to the
account--than fifteen mètres (fifty feet) long, without reckoning its
eight formidable arms, covered with suckers, and about twenty feet in
circumference at its largest part, the head terminating in many arms of
enormous size, the other extremity terminating in two fleshy lobes or
fins of great size, the weight of the whole being estimated at four
thousand pounds; the flesh was soft, glutinous, and of reddish-brick
colour.

The commandant, wishing in the interests of science to secure the
monster, actually engaged it in battle. Numerous shots were aimed at it,
but the balls traversed its flaccid and glutinous mass without causing
it any vital injury. But after one of these attacks the waves were
observed to be covered with foam and blood, and, singular thing, a
strong odour of musk was inhaled by the spectators. This musk odour we
have already noticed as being peculiar to many of the Cephalopods.

The musket-shots not having produced the desired results, harpoons were
employed, but they took no hold on the soft impalpable flesh of the
marine monster. When it escaped from the harpoon it dived under the
ship, and came up again at the other side. They succeeded at last in
getting the harpoon to bite, and in passing a bowling hitch round the
posterior part of the animal. But when they attempted to hoist it out of
the water the rope penetrated deeply into the flesh, and separated it
into two parts, the head with the arms and tentacles dropping into the
sea and making off, while the fins and posterior parts were brought on
board: they weighed about forty pounds.

[Illustration: Plate XXIV.--Gigantic Cuttle-fish caught by the French
Corvette Alecton, near Teneriffe.]

The crew were eager to pursue, and would have launched a boat, but the
commander refused, fearing that the animal might capsize it. The object
was not, in his opinion, one in which he could risk the lives of his
crew. PL. XXIV. is copied from M. Berthelot's coloured representation of
this scene. "It is probable," M. Moquin-Tandon remarks, commenting on
M. Berthelot's recital, "that this colossal mollusc was sick or
exhausted by some recent struggle with some other monster of the deep,
which would account for its having quitted its native rocks in the
depths of the ocean. Otherwise it would have been more active in its
movements, or it would have obscured the waves with the inky liquid
which all the Cephalopods have at command. Judging from its size, it
would carry at least a barrel of this black liquid, if it had not been
exhausted in some recent struggle."

"Is this mollusc a calmar?" asks the same writer. "If we might judge
from the figure drawn by one of the officers of the Alecton during the
struggle, and communicated by M. Berthelot, the animal had terminal
fins, like the calmars; but it has eight equal arms, like the
cuttle-fish. Now the calmars have ten, two of them being very long. Was
this some intermediate species between the two? Or must we admit, with
MM. Crosse and Fisher, that the animal had lost its more formidable
tentacles in some recent combat?"[13]

The fifth family, _Octopodidæ_, contains _Eledone_, _Octopus_,
_Pinnoctopus_, _Cirroteuthis_, _Philonexis_, and _Scærgus_.

The _Octopoda_, without tentacles, have eight long arms, united at the
base by a web; the suckers in two rows, which are sessile; the eyes
fixed; shell, two short stiles enclosed in the mantle; the body united
to the head by a broad neck-band; no side-fins; shell internal and
rudimentary in the British species; body oval, warty, and without fins,
in _Octopus_; small and oblong, arms tapering and webbed, and suckers in
a single row, in _Eledone_ (Fig. 321).

[Illustration: Fig. 321. Eledone, Octopus vulgaris (Lamarck).]

In his great work, Professor Owen proposes to divide the Cephalopods
into two groups, which he calls _Dibranchiata_, characterised by the
presence of two branchiæ, which would bring together all the naked
Cephalopods, including Sepia, Loligo, Octopus, Kassia, and Ommastrephos;
and _Tetrabranchiata_, having four branchiæ, to which the _Nautilus_,
and most of the fossil Cephalopods, such as the _Ammonites_, belong.
Most of the first group are represented in the British seas, but the
second are altogether absent.

[Illustration: Fig. 322. Octopus macropus (Risso).]

[Illustration: Fig. 323. Octopus brevisses (D'Orbigny).]

[Illustration: Fig. 324. Octopus horridus (D'Orbigny).]

The _Decapoda_ are of all sizes. Dr. Grant describes the body, or
mantle, of _Sepiola vulgaris_, found on our coast, as measuring about
six lines in length, and as much in breadth, while the head measures
four lines in length, and, from the magnitude of the eyes, must be equal
in breadth with the body. In _Onychoteuthis_, distinguished for its
uncinated suckers, they are found of the size of a man. In Cook's first
voyages, the naturalists to the expedition, "Banks and Solander," to
quote Professor Owen's account, "found the dead carcase of a gigantic
species of this kind floating in the sea between Cape Horn and the
Polynesian Islands, in 30° 44' S. lat., and 110° 10' W. long. It was
surrounded by sea birds, which were feeding on its remains. From the
parts of this specimen which are still preserved in the Hunterian
Museum, and which have always strongly excited the attention of
naturalists, it must have measured at least six feet from the end of the
tail to the end of the tentacles."

In the genus _Eledone_ the arms are reunited at their base by a very
short membrane, with only a single row of suckers. The two best-known
species of this group inhabit the Mediterranean. The one is _Eledone
moschatus_, known in Italy under the name of Muscardino, from the strong
odour of musk which it emits, even after death and desiccation; the
other is _Eledone cirrhosus_, a small species, bluish-grey on the back,
and whitish under the belly.

The habits of _Eledone moschatus_ have been carefully studied by M.
Verany. The able naturalist of Nice preserved many of these animals
during a month, in a great aquarium, noting their habits. When in a
state of tranquillity, the _Eledone_ clung to the sides of the glass
tank in which it was kept. Its head is then inclined forwards, with the
sac hanging behind; the locomotive tube, turned upwards, presents the
orifice between the arms. In this state the animal is yellowish in
colour, its eyes dilated, its inspirations regular. But if irritated, a
remarkable change takes place: its body assumes a fine maroon colour,
and it is covered with numerous tubercles; the eye becomes contracted, a
column of water is forcibly ejected from the locomotive tube at the
aggressor, and the respiration becomes precipitate, jerky, and
irregular. The creature would take a strong inspiration, and, having
collected its force, suddenly throw a jet of water to a distance of more
than three feet. This state of passion, which the slightest touch is
sufficient to produce, endures for half an hour or more. When it ceases,
the animal resumes its form and primitive colours; but the least shock
impressed on the water is sufficient to give it a deeper tint, which
passes like a flash of lightning over the skin of this singular proteus.

The Eledone sleeps by day as well as by night, attaching itself in its
sleep to the walls of its prison, leaving its arms to float around, the
two inferior ones extending backwards, and the sac inclining over them;
its eyes are then contracted, and in part covered by the eyelids. Its
respiration is regular and slow, and any ejection of water very rare;
its colour is then of a livid grey, and vinous red below, with whitish
spots, while the brown spots have now entirely disappeared. While still
asleep, it is watchful and attentive to all the dangers which could
surprise it. The extremities of the arms floating round its body are
ready to announce the approach or contact of any other object. Even the
most delicate touch is perceived immediately, and it shrinks from the
hand which seeks to approach. Under every circumstance the Eledone
exhales a strong odour of musk, which it preserves long after death.

When the Eledone swims, which it rarely does unless pressed by some
urgent necessity, it carries the sac in advance, the arms floating
behind--the six upper ones being on a horizontal line, the two others
approaching each other below. Thus arranged, it presents, in consequence
of its flattened form, a very large resisting surface to the water, its
progress being due to the alternate dilatation and contraction of the
body, which expels the water through the locomotive tube, and by
reaction produces a rapid and jerking movement. Sometimes the arms aid
the movement; the eyes of the animal are then much dilated, and its
colour a clear livid yellow, finely shaded with red, and covered with
bright spots.

[Illustration: Fig. 325. Pinnoctopus corolliformis (D'Orbigny).]

[Illustration: Fig. 326. Cirrotheutis Mittleri (Eschricht).]

It is a singular fact that the creature notably changes colour under any
exertion, so that the animal at rest and in motion are two different
beings. When walking under water the tube is directed behind, its arms
are spread out, the head is raised, and the body slightly inclined
forward; its mantle is then of a pearly grey, and the spots take the
tint of wine lees. When at rest the shades disappear.

The _Pinnoctopus_ (Fig. 325), another genera of this family, have the
body oblong, with lateral expansions, as represented in the accompanying
figure.

In _Cirrotheutis_ the arms are completely united in their whole extent
by a thin membrane furnished with cirri, which alternate with certain
suckers arranged in one row. Only one species of this genera is known as
an inhabitant of northern seas, which is represented in Fig. 326.

The sixth family, _Argonautidæ_, contains only _Argonauta_.

The Argonauta, or Paper-nautilus. Floating gracefully on the surface of
the sea, trimming its tiny sail to the breeze, just sufficient to ruffle
the surface of the waves, behold the exquisite living shallop. The
elegant little bark which thus plays with the current is no work of
human hands, but a child of Nature: it is the Argonaut, whose tribes,
decked in a thousand brilliant shades of colour, are wanderers of the
night in innumerable swarms on the ocean's surface.

The marine shell which Linnæus called the Argonaut enjoyed great renown
among the ancient Greeks and Romans. It was the subject of graceful
legends; it had inspired great poets; it occupied the attention of
Aristotle, who called it the _Nautilus_ and _Nauticos_, and of Pliny,
who called it _Pompylius_. Few animals, indeed, have been so celebrated,
so anciently known. The Greek and Roman poets saw in it an elegant model
of the ship which the skill and audacity of the man constructed who
first braved the fury of the waves; in the words of the poet, "armour of
triple oak and triple brass covered the heart of him who first confided
himself in a frail bark to the relentless waves:"

    "Illi robur et æs triplex
      Circa pectus erat, qui fragilem truci
    Commisit pelago ratem
      Primus...."

    _Horace_, I. Car. iii. l. 9.

To meet the Pompylius was, according to the superstitious Roman, a
favourable presage. This little oceanic wanderer, in spite of the
capricious waves, was a tutelar divinity, who guarded the navigator in
his course, and assured him of a happy passage. Listen to the immortal
author of the first Natural History of Animals, the philosophical
Aristotle. "The Nautilus Polyp," says the learned historian, "is of the
nature of animals which pass for extraordinary, for it can float on the
sea; it raises itself from the bottom of the water, the shell being
reversed and empty, but when it reaches the surface it readjusts it. It
has between the arms a species of tissue similar to that which unites
the toes of web-footed birds. When there is a little wind, it employs
this tissue as a sort of rudder, letting it fall into the water with the
arms on each side. On the approach of the least danger it fills its
shell with water, and sinks into the sea."

Pliny gives it the name of Pompylius, and, after the example of
Aristotle, explains how it navigates, by elevating its two first arms, a
membrane of extreme tenuity stretching between them, while it rows with
the others, using its median arm as a rudder. The Greek poet, Oppian,
who lived in the second century of our era, and to whom we are indebted
for Poems on Fishing (_Halieutica_) and the Chase (_Cynegetica_), says
of it: "Hiding itself in a concave shell, the Pompylius can walk on
land, but can also rise to the surface of the water, the back of its
shell upwards, for fear that it should be filled. The moment it is seen,
it turns the shell, and navigates it like a skilful seaman: in order to
do this, it throws out two of its feet like antennæ between which is a
thin membrane, which is extended by the wind like a sail, while two
others, which touch the water, guide, as with a rudder, the house, the
ship, and the animal. If danger approaches, it folds up its antennæ, its
sail, and its rudder, and dives, its weight being increased by the water
which it causes to enter the shell. As we see a man who is victor in the
public games, his head circled by a crown, while vast crowds press
around, so the Pompylius have always a crowd of ships following in their
track, whose crews no longer dread to quit the land. O fish justly dear
to navigators! thy presence announces winds soft and friendly: thou
bringest the calm, and thou art the sign of it."

Oppian carried his admiration a long way. That the Argonaut is an
animated skiff is agreed on all hands; but, in making it almost a
bird--in according to it at once the faculty of gracefully navigating
the sea and floating in the atmosphere as an inhabitant of the regions
of air--he was passing the limits permissible to poetic license.

But the properties of the Nautilus has not alone struck the imagination
of the Greeks and Romans; it also attracted the attention of the
Chinese, who call it the boat-polyp. Rumphius informs us, that in India
the shell fetches a great price (Fig. 327). Women consider it a great, a
magnificent ornament. In their solemn fêtes dancers carry one of these
shells in the right hand, holding it proudly above their heads. Nor did
it require the dithyrambic praises with which the ancients have
surrounded it to recommend it to the admiration of modern naturalists.
Without exaggerating the graceful attributes with which it is gifted, it
is at once one of the most curious objects in Nature.

[Illustration: Fig. 327. Shell of Argonauta argo (Linnæus).]

[Illustration: Fig. 328. The Argonauta argo (Linnæus).]

Its body (Fig. 328) is ovoid in form, and it is furnished with eight
tentacles, covered with a double row of suckers. Of these tentacles, six
are narrow and slender, tapering to a point towards the extremity, while
two of them expand toward the extremity in the form of wings or sails.
These are all folded up when in a state of repose. The body itself is
contained in a thin, white, and fragile univalve shell, which is oval,
flattened on the exterior, but rolled up in a spiral in the interior,
the last turn of the shell being so large as to give it something of the
form of an elegantly-shaped shallop. Singularly enough, the body of the
animal does not penetrate to the bottom of the shell, nor is it attached
to it by any muscular ligament; nor is the shell moulded exactly upon
it, as is the case with most other testaceans.

What does all this imply? Is the Argonaut a parasite? a fraudulent
disinheritor? a vile assassin, who, having surprised and killed the
legitimate proprietor of the shell, has installed itself in its place,
and in the proper house of its victim? Such crimes are not without
example in the natural history of animals--witness the proceedings of
the curious _hermit crab_, whose proceedings we shall glance at in a
future chapter. The parasitic character of the Nautilus was long
conceded by naturalists; but recent facts have corrected this opinion.
We have collected their shells, of all dimensions and of all ages,
inhabited always by the same animal, whose size is always proportioned
to the volume of the shell. More than that, it is now known that in the
egg of the Nautilus the rudiments of the shell exist. M. Chenu tells us,
that under the microscope Professor Duvernoy discovered a distinct shell
contained in the embryo. Sir Everard Home asserts the contrary; and no
opportunity presented itself for the complete solution of the question,
until Poli was placed by the King of Naples in a position to solve it.
The piscina of Portici was placed at his disposal. He witnessed the
curious mechanism by which the egg is expelled from the uterus, having a
shell, and satisfied himself, by following their development day by day,
that the shell existed in the embryo, and grew with the animal. He
satisfied himself also that the opinion enunciated by Aristotle, that at
no point did the animal adhere to the shell, was perfectly true.

Finally, in the curious series of experiments carried on by Madame
Power, in the port of Messina, the fragments of the frail bark of the
mollusc, which were broken off in taking it, were restored in a few
days, having been reproduced. It is, therefore, quite demonstrated that
the Nautilus, like other testaceous molluscs, itself secretes and
constructs its shell--its diaphanous skiff. The reader, however, must
not flatter himself that he can witness with his own eyes from the
shore, in our narrow channel, the charming picture of the Nautilus
painted by poets and natural historians: they never come near the shore.
They are timid and cautious creatures, dwelling almost always in the
open sea. They live in families, some hundreds of miles from the shore;
and it is during the night, or at most in the fading light of sunset,
that they assemble together to pursue their gambols on the surface of a
tranquil sea.

[Illustration: Fig. 329. Argonauta papyracea, as it swims by means of
its locomotive tube.]

However reluctant we may be to destroy the marvellous fictions of
ancients and moderns, we are compelled to declare that there is no truth
in the often-repeated statement that the Nautilus uses its palmated arms
as oars or sails. In order to swim on the surface, it comports itself as
all other Cephalopods do. It uses neither oars nor sails, and the
palmate arms only serve to envelop and retain its hold on its frail
shell. Its principal apparatus of progression is the _locomotive tube_
with which it is furnished, in common with all Cephalopods, and which is
in the Nautilus very long. Aided by this apparatus, it ejects the water
after it has served the purpose of respiration, and, in doing so,
projects itself against the liquid, as it were. While it advances
through the water under this impulse, its pendent arms, elongated and
reunited in bundles, extend the whole length of the shell. Fig. 329
shows the position of the different parts of the animal when it thus
breasts the waves. These arms are also powerful aids when the animal
creeps on the ground at the bottom of the sea.

[Illustration: Fig. 330. Argonauta papyracea in its shell.]

When the animal is disturbed it retires completely into its shell. From
that moment, the equilibrium being changed, the shell is overturned, and
the animal is nearly invisible. If frightened, it entirely submerges
itself, and sinks to the bottom.

These little beings share with other Cephalopods the strange faculty of
changing colour under the influence of some vivid impression; but their
graceful and delicate organization redeems them from the charge we have
brought against the cuttles. The Nautilus can blush, turn pale, and show
through its transparent shell its body changing in sudden shades; but it
never exhibits those bristling, unpleasant tubercles, the hideous
inheritance of the larger and coarser Cephalopods--the tyrants of the
sea.

The male Argonauts are very small, often not a tenth part of the size of
the females, which alone possess the shells.

The Nautilus carries its egg in the shell, and the little ones are also
hatched in this floating cradle. Four species are at present known: the
species described by Aristotle and Pliny, and the more ancient
naturalists; namely, _A. argo_, or _papyracea_ (Figs. 327 and 329),
which are inhabitants of the Mediterranean as well as the Indian Ocean
and the Antilles. Two others, _A. tubercula_, belonging exclusively to
the Indian Ocean, and _A. baillant_, which is met occasionally in the
Pacific and Atlantic Oceans.

       *       *       *       *       *

The nautilus belongs to the section of Octopoda, and the class of
Acetabuliferous Cephalopods, having, as the name indicates, eight feet,
from ὀκτὼ, _eight_, and ποῦς, _foot_; at the same time the body
is entirely fleshy, and without fins. The genera of cuttles (_Sepia_)
and Calmars (_Loligo_) belong to another section of the same class;
namely, the Decapoda, because they have ten feet and a sort of internal
osselet, with fins, &c.


THE DISTRIBUTION OF THE MOLLUSCA.

We have thought it better to treat this subject in a separate chapter,
for its vast and complicated nature renders it otherwise difficult to
handle, except in a space which would exceed the limits of this work.

The different genera of the organic world are peculiar to, or most
frequent in, certain localities, and even species and varieties have
their limits. This habit pervades the entire range of organisms, from
the lowest plants to man, whose qualities are to a great extent the type
of the locality he inhabits. The geography of the Mollusca is perhaps
the best known to science. The labours of Mr. Louis Agassiz, Dr.
Sclater, and Professor Edward Forbes, have done much towards giving us a
clear idea of zoological geography. Climate alone is insufficient to
account for the distribution of animals: some higher cause rules here.
But while we admit this, still we must acknowledge that climate exerts
considerable influence in modifying the qualities of species.

The distribution of the Mollusca may be considered from three points of
view. First, as regards _geography_; second as regards _depth_; and
third as regards _time_; the last belongs to geology.

We shall now survey the principal divisions of the ocean; the line of
demarcation being drawn, not by latitude or longitude, but by genera and
species.

The Mollusca of the Arctic seas are well known to show considerable
analogy with those of the later Tertiary periods of Europe. Hence the
great interest connected with their comparison, as it affords,--provided
we are satisfied with this line of argument,--a proof that an Arctic
climate formerly existed in temperate regions. It is the northern Drift
of which we are speaking. Even when species are found living in Britain
identical with those of the Arctic regions, still there is often a
difference in the form or size of British and Arctic specimens; certain
species, such as _Cyprina Islandica_, being comparatively small in the
south of Britain, larger in Shetland, and attaining their greatest size
in Iceland.

The countries included in the Arctic molluscan province are Lapland,
Iceland, Greenland, the west coast of Davis' Straits, and Behring's
Straits. About two hundred species are enumerated by the various Arctic
voyagers, as found in these seas; of these about one-half are peculiar
to these seas, and the other half are either found living in the
temperate regions of Europe, or in their so-called glacial strata.

The Boreal province includes the North Atlantic, from Nova Scotia to
Iceland, and from thence to Faroe, Shetland, and the Norway coast.

The number of species is very large; and more than one-half are common
both to Scandinavia and the North American coast, while a great number
also are found on the British coast.

The province called Celtic by Professor Edward Forbes embraces the
coasts of Britain, Sweden, and Denmark.

Our British mollusca are about seven hundred in number; those bearing
shells are above five hundred. Of these about thirty are peculiar to
Britain. The shells of the Baltic are identical with those of this
province.

The Lusitanian province stretches from Madeira and the Canaries to the
coasts of Spain and Portugal, and includes also the Mediterranean. But
as one might expect, on close examination, the Mollusca in so large an
area differ so widely that we are forced to admit the existence of great
divisions.

The number of species found on the coast of Madeira by Mr. McAndrew was
one hundred and fifty-six, of which forty-four per cent. were identical
with British species, and eighty-three found near the Canaries.

The shells of the Mediterranean are six hundred in number, but it is
probable that more extensive dredging will result in great accessions
being made to this list. A very small number of species only are
identical with those now found in the West Indies.

Nine genera are peculiar to the Mediterranean.

In the character of its shells, the Black Sea resembles the
Mediterranean, but does not contain much more than a tenth of the number
of its species. The number of shells found on the Spanish and Portuguese
coasts is much smaller than one would expect, and can only be attributed
to the scanty explorations that have been made. As we might expect, the
number of species identical with those of Northern Europe is much
greater on the Atlantic than on the Mediterranean coast of Spain.

The sea of Aral, and the Caspian, contain a few peculiar species; but
they have been so little explored, that it is premature, we think, to
form them into a province. The proportions of salt contained in these
seas is much less than in the ocean.

The west of Africa affords a considerable number of fine shells; the
species most numerous being those of Murex, Conus, and Clavatula.

The south African province contains four hundred species; the
characteristic genera are Terebratella, Chiton, Patella, Trochus,
Fissurella, Cypræa, and Conus. A large number of these species are not
found elsewhere.

The Indo-Pacific province stretches from Australia to Japan; the
greater part of the east coast of Africa; the Red Sea; Persian Gulf; the
Asiatic coast, and the islands of the Indian Archipelago.

The molluscs of the Red Sea remind us of those of India; the percentage
of those found also in the Mediterranean being much less. The shells of
the Persian Gulf are but little known; one species, the brindled cowry
(_Cypræa princeps_), has been sold for fifty pounds.

The seas of New Zealand and Australia have been formed into a province.
As might be anticipated, their mollusca have little in common with those
of the rest of the globe.

The Japonic province includes the coast of Japan and the Corea.

The Aleutian province, the centre of which may be taken to be the
Aleutian islands, shows great analogy with the Boreal province of the
west, a considerable number of the shells being identical--a fact
especially interesting when we consider that very few species are found
common to both the south-eastern and south-western coasts of America.

The Californian province is very distinct from that of Panama; the most
numerous genera found there, are Chiton, Acmæa, Fissurella, Trochus, and
Purpura.

The marine shells of Panama are upwards of thirteen hundred; the region
included stretches from the Gulf of California to Peru. For our
knowledge of this province we are much indebted to the researches of Dr.
P. P. Carpenter, who has catalogued six hundred and fifty-four species,
as found at Mazattan.

The Peruvian province contains a long list of species, and extends from
Callao to Valparaiso.

The Magellanic province includes the extreme south of America and the
Falkland Islands. Many genera, the species of which are usually small,
here reach an enormous size, and afford, in many cases, the chief animal
food consumed by the quadrupeds and human population of that wild and
desolate coast.

The Patagonian province extends from St. Catharina to Point Melo on the
east coast.

The number of species found also in the Falkland Islands is very small;
but a large number are identical with Brazilian species; yet the
majority are peculiar.

The Caribbean province extends from Brazil to the West Indies, and
includes, also, the northern coast of South America and the Gulf of
Mexico; a total of fifteen hundred species is enumerated by Professor
Adams as belonging to the province.

The Transatlantic province, or that on the coast of the United States,
does not afford a large number of species, only two hundred and thirty
being known; of these, only fifteen are found in Europe.

The study of the terrestrial and fresh-water mollusca affords even
better grounds for their division into provinces; but we shall not enter
into it here, as it belongs to the Land World.

       *       *       *       *       *

We shall now say a few words on the depth of the sea, or ocean, in which
Mollusca are found.

The observations of Milne Edwards, Audonin, and Professor Edward Forbes,
have led to the division of the sea into four zones.

The deep sea Coral zone, from fifty to one hundred fathoms; the
Coralline zone from fifteen to fifty fathoms; the Laminarian zone, which
stretches from fifteen fathoms to low water; and the Littoral zone,
between high and low water marks. The great stronghold of Crania,
Thetis, Neæra, Yoldia, Dentalium, and Scissurella, is in the deep sea
Coral zone; while Buccinum, Fusus, Pleurotoma, Natica, Aporrhais,
Philine, and Velutina, which are among the most ravenous and predatory
of molluscs, are found in the Coralline zone. They attack the bivalves,
whose shells among the relics of former seas, as in those of the
present, show evidence of an assault and a murder.

The principal genera of the Laminarian zone are the Nudibranchiata,
Aplysia, Trochus, Nacella, Rissoa, and Lacuna, which feed so much on the
seaweed of this region.

The Littoral zone, which being accessible as the tide recedes, is best
known, affords Cardium, Mytilus, Tellina, Solen, Trochus, Patella,
Littorina, and Purpura; or in plain English, cockles, mussels,
razor-fish, limpets, periwinkles and tingles;--species which are the
first to attract our attention, and which are so much used for food.


FOOTNOTES:

[Footnote 13: Is it necessary to say that even this account--apparently
so well authenticated, not to speak of the representation drawn on the
spot--should be taken "cum grano salis?"--ED.]



CHAPTER XVII.

THE CRUSTACEA.

    "Multa tamen lætus tristia pontus habet."

    OVID.


The animals of this class, as regards organisation, must be placed
higher in the scale than the Arachnidæ, or spiders; but they are beneath
the Mollusca, although as regards affinity, the Mollusca in their lower
division--the Molluscoïda--more approximate to the Polyp class than to
the Crustacea.

The Crustacea is the highest division of articulate animals with feet;
they breathe by means of gills, and have no stigmata, or air-passages,
as in insects. The name signifies a hard crust or covering, with which
the animals are protected. This consists of layers of carbonate of lime
with one of pigment, generally, but not always, on the surface. The
general outline of these animals is peculiar; unlike insects, they are
not divisible into head, thorax, and abdomen; many species truly have no
head at all; but a pair of eyes point to the seat of intelligence. Most
of these animals have two compound eyes; but a few, like some insects,
have both simple and compound eyes. The mouth is situated in the under
part of the anterior of the body: in some cases they have jaws, as in
crabs; in others suckers only.

Passing over the vast numbers of beings which inhabit the debatable
ground--the _Annelids_, which were for ages confounded with the worms,
because of their resemblance in form:--a form which might be declared
forbidding, but, as Aristotle has well said, Nature, in her domain,
knows nothing low, nothing contemptible; the sea-leeches, whose
condition was an impenetrable mystery to Pliny, "Omnia incerta ratione,
et in naturæ majestate abdita;" and the singular cirripedes, one species
of which, the barnacle (_Anatifa lævis_), was thought by old Gerard,
the herbalist, and in his day by many others, to be the egg from which
the barnacle goose was produced--passing over these ocean tribes, we
reach the Crustaceans--the Insects of the Sea; of greater size, force,
and voracity than any land insect with which we are acquainted. They are
armed, also, at all points; for, in place of the coriaceous tunic, they
are clothed in calcareous armour, both hard and strong, and bristling
with coarse hairs, spiny tubercles, and even serrated spines.

The Crustaceans have nearly all of them claws, formidably hooked and
toothed, which they employ as pincers, both in offensive and defensive
war. They have been compared to the heavily-armed knights of the middle
ages--at once audacious and cruel; barbed in steel from head to foot,
with visor and corslet, arm-pieces and thigh-pieces--nothing, in fact,
is wanting to complete the resemblance.

These marine marauders live on the sea-coast, among the rocks, and near
the shore. Some few of them frequent the deep waters, others hide
themselves in the sand or under stones, while the common crab (_Carcinus
mœnas_, Leach) loves the shore almost as much as the salt water, and
establishes itself accordingly under some moist cliff overhanging the
sea, where it can enjoy both.

One of the necessary consequences of the condition of these animals,
enclosed in a hard shell, is their power of throwing it off. The
solidity of their calcareous carapace would effectually prevent their
growth, but at certain determinate periods Nature despoils the warrior
of his cuirass; the creature moults, and the calcareous crust falls off,
and leaves it with a thin, pale, and delicate tunic. In this state the
Crustacean is no longer worthy of its name--its skin has become as
vulnerable as that of the softest mollusc; but it has the instinct of
weakness--it retires into lonely places, and hides its shame in some
obscure crevice, until another vestment, more suitable for resistance,
and adapted to its increased size, has been restored.

The Crustacean has not a vertebral column. The covering of the
Crustacean consists of a great number of distinct pieces, connected
together by means of portions of the epidermis which have not yet become
hardened, in the same way as the bones in the skeleton of the vertebrata
are connected by cartilages, the ossification of which only takes place
in old age. The covering of the Crustacean consists of a series of rings
varying in number, the normal number of the body-segments being
twenty-one. Each ring is divisible into two arcs--one upper, or dorsal,
the other lower, or ventral; and each arc may present four elementary
pieces, two of which are united in the mesial line from the _tergum_, or
back; the lower arc is a counterpart of this, while the others form the
two side, or epimeral, pieces. The skin, therefore, performs the
functions of a skeleton, so that the Crustaceans, as was said by
Geoffroy Saint Hilaire, like the molluscs, live inside and not outside
the bony column. The analogue of the Crustacea amongst vertebrata is to
be found amongst Sturgeonidæ, whose hard, immovable bony case encloses a
softer skeleton; agreeing in its characters with that of the higher
divisions of vertebrata, although not possessing the solidity of bone.

The Crustaceans vary greatly in colour; some are of a dark, iron-grey,
with a dash of steel-blue, like metal weapons forged for combat; a few
of them are red, or reddish-brown; others are of an earthy yellow, or of
a livid blue.

"The integument," according to Milne Edwards, "consists of a _corium_,
or true skin, and epidermis, with a pigmentary matter, which colours the
latter. The corium is a thick, spongy, and vascular membrane, connected
with the serous substance which lines the parietal walls of the
cavities, as the serous membrane lines the internal cavities among the
vertebrata." This pigment is less a membrane than an amorphous matter
diffused through the outer layer of the superficial membrane, which
changes to red in the greater number of species in alcohol, ether,
acids, and water at 212° Fahr.

The calcareous crust of the animal is thick, and in the dorsal region
capable of great resistance; their members are also of remarkable
hardness; but in the smaller species the shell is often thin, and of
that crystalline transparency which permits of its digestion and
circulation being observed. Many species, which are quite microscopic,
contribute colour to the sea--red, purple, or scarlet: such are
_Grimothea D'Urvillei_ and _G. gregarea_.

Before the year 1823, it was not generally supposed that this class of
animals was subject to change of shape from the larva condition, and
during its progressive development; but about this time, and for some
years following, certain able microscopic experiments clearly
demonstrated that a minute nondescript kind of animal called the _Zoea
Taurus_, was nothing more nor less than the young of a kind of Prawn as
when extracted from the egg. Mr. Vaughan Thomson, by many successive
observations, and under the fire of much adverse criticism,
satisfactorily established the truth of metamorphic change in many
genera, and, in particular, in regard to the common crab (_Cancer
pagurus_); having succeeded in hatching the ova of this species, the
product of which were fine Zoeas. That there are variations in the
channel of this law of change has been admitted, but that generally a
metamorphosis exists, analogous to that of insects, in the various
genera of Crustacea, with hardly an exception, has been clearly
established.

[Illustration: Fig. 331. Zoea Taurus.]

The recorded observations of the eminent naturalist we have mentioned,
Mr. Thomson, as well as those of Mr. Couch, of Penzance, Mr. Milne
Edwards, and particularly those of the last mentioned, the learned
author of perhaps the best work extant on the Crustacea, are referred to
as treating most lucidly on this interesting subject.

As an illustration of this metamorphosis, we give figures of the _Zoea
Taurus_ in two states, viz., Fig. _a_, in the first stage; and second,
Fig. _b_, as the animal appeared on the fourth day after the first
microscopic examination, and when it resolved itself into a kind of
prawn. The drawings appear in Mr. Bell's "History of British Stalk-eyed
Crustacea," and were taken by that gentleman from the work of a Dutch
naturalist, named Slabber, who made the original observation in the year
1768, and published the result in 1778, from which time the subject had
been allowed to fall asleep until revived by Mr. Thomson.

Among the sea-spiders, which have no neck (_Cephalothorax_), the head
gradually disappears in the breast, but the belly remains distinct; the
middle of the body is compressed, the shape narrow and graceful. Among
the Crustaceans which have neither neck nor shape, the head, the breast,
and the belly form only one mass, often short, squat, athletic, and
difficult to take, as in _Pisa tetraodon_ (Fig. 332), the four-horned
spider-crab.

[Illustration: Fig. 332. Pisa tetraodon.]

Many of these animals have a powerful tail, consisting of a certain
number of ciliated paddles, which it uses in swimming to beat the water,
and to confuse its enemies.

The Crustaceans, so far as they are aquatic, respire by means of
_branchiæ_, or gills. In the larger species these branchiæ are
lamellous, or with filaments, whose supports are traversed by two
canals, one of which leads the blood into the general economy, the other
directs it towards the heart. These organs are enclosed in the body. In
the smaller species the branchiæ often appear exteriorly, hanging in the
water like a fungus. Sometimes these are at once swimming and breathing
organs; in other cases the animal has no special organs of respiration.

Nearly all the Crustaceans are strong, hardy, and destructive, forming a
horde of nocturnal brigands--merciless marauders, who recoil from no
trap in which they can lie in wait for their prey. They fight _à
l'outrance_ not only with their enemies, but often among themselves,
either for a prey or for a female, sometimes for the sake of the fight.
The miserable creatures struggle audaciously with their claws. The
carapace generally resists the most formidable blows; but the feet, the
tail, and, above all, the antennæ, suffer frightful mutilation. Happily
for the vanquished, the mutilated members sprout again after a few weeks
of repose. This is the reason for the many Crustaceans met with having
the talons of very unequal size: the smaller are those lost in battle
replaced. Nature has willed that the Crustacean should not long remain
an invalid. They soon return cured of their wounds. "We have seen
lobsters," says Moquin-Tandon, "which have in an unfortunate rencounter
lost a limb, sick and debilitated, reappear at the end of a few months
with a perfect limb, vigorous, and ready for service. O Nature, how thou
fillest our souls with astonishment and wonder!"

On the Spanish coast there is a species of crab, known, singularly
enough, by the name of _Boccaccio_; it is caught for its claw, which is
considered excellent eating. This is cut off, and the mutilated animal
is thrown into the sea, to be taken at some future time when the claw
has reappeared.

Crustaceans are nearly all carnivorous, and eat eagerly all other
animals, whether living or dead, fresh or decomposed. Little think they
of the quality or condition of their food. It is amusing to witness the
address and gravity with which the common crab, when it has seized an
unfortunate mussel, holds the valve open with one claw, while with the
other it rapidly detaches the animal, carrying each morsel to the mouth,
as one might do with the hand, until the shell is entirely empty. The
crab does not kill its prey directly, like the lobster; it is swallowed
also, but with greater appreciation.

M. Charles Lespés surprised upon the shore at Royan a shoal of crabs at
their repast. This day they seem to have dined in common, and "God knows
the enjoyment," as the good Fontaines said. They were in rows, every
head turned to the same side, and nearly on end on their eight feet.
They seized the small objects on the shore, which were carried to the
mouth, each hand in its turn in regular order: when the right hand
reached the mouth the left was on the ground. Let us just figure to
oneself a company of disciplined soldiers messing together at the same
table!

The Long-horned Corophius (_Corophium longicorne_), remarkable for its
long antennæ, knows perfectly well how to cut the byssus by which the
mussels suspend themselves, in order that the bivalve may fall on the
weeds among them. Other Crustaceans, also great oyster-eaters, have the
cunning or instinct to attack the mollusc without exposing themselves to
danger. When the bivalve half opens its shell to enjoy the rays of the
sun or take food, the evil-disposed Crustacean slips a stone between the
valve. This done, it devours the poor inhabitant of the shell at its
leisure.

The Corophius, respecting whom this question is hazarded, are extremely
numerous on the shores of the Atlantic towards the end of summer and
autumn. They make constant war upon certain marine worms. Off the coast
of La Rochelle they may be seen in myriads beating the muddy bottom with
their long antennæ in search of their prey. Sometimes they meet one of
these Nereida or Arenicola many times their own size, when they unite in
a body to attack it. In the oyster beds of La Rochelle they are useful
friends to the oyster by destroying these enemies, although they do not
hesitate to attack the mollusc when it comes in their way. During the
winter the mud of the bouchots gets piled up in unequal heaps, and when
the warm season returns, it has become hard and unfit for the
cultivation of the mollusc. It is necessary to level and dry these
mud-heaps--a process which would be both difficult and costly. Well, the
Corophia charge themselves with the task. They plough up annually many
square leagues covered with these heaps. They dilute the mud, which is
carried out by the ebbing tide, and the surface of the bay is left
smooth, as it was in the preceding autumn.

We have said that the Crustaceans do not even respect each other; the
larger of the same species often devour the smaller. _Rara concordia
fratrum!_ Mr. Rymer Jones relates that he had on one occasion introduced
six crabs (_Platycarcinus pagurus_) of different size into an aquarium.
One of them, venturing towards the middle of the reservoir, was
immediately accosted by another a little larger, which took it with its
claws as it might have taken a biscuit, and set about breaking its
shell, and so found a way to its flesh. It dug its crooked claws into it
with voluptuous enjoyment, appearing to pay no attention to the anger
and jealousy of another of its companions, which was still stronger and
as cruel, and advanced towards them. But, as Horace says--and he was not
the first to say it--"No one is altogether happy in this lower world":

    "Nihil est ab omni parte beatum."

Our ferocious Crustacean quietly continued its repast, when its
companion seized it exactly as it had seized its prey, broke and tore it
in the same fashion, penetrating to its middle, and tearing out its
entrails in the same savage manner. In the mean time the victim,
singularly enough, did not disturb itself for an instant, but continued
to eat the first crab bit by bit, until it was itself entirely torn to
pieces by its own executioner--a remarkable instance at once of
insensibility to pain and of cruel infliction under the _lex talionis_.
To eat and to be eaten seems to be one of the great laws of Nature.

Though essentially carnivorous, the Crustaceans sometimes eat marine
vegetables. Many even seem to prefer fruit to animal food. Such is the
robber-crab (_Birgus latro_) of the Polynesian Isles, which feeds almost
exclusively on the cocoa-nut. This crab has thick and strong claws; the
others are comparatively slender and weak. At first glance it seems
impossible that it could penetrate a thick cocoa-nut surrounded by a
thick bed of fibre and protected by its strong shell; but M. Liesk has
often seen the operation. The crab begins by tearing off the fibre at
the extremity where the fruit is, always choosing the right end. When
this is removed, it strikes it with its great claws until it has made an
opening; then, by the aid of its slender claws, and by turning itself
round, it extracts the whole substance of the nut.

The Crustaceans have eyes of two kinds--simple and compound: the first
are sessile and immovable, and very convex; the other borne on a short
calcareous stem or peduncle, and formed of a number of small eyes
symmetrically agglomerated--the reunion of all the microscopic cornea of
a composite eye, resembling in shape a cap formed of facets. It is said,
for instance, that the eye of the lobster consists of 2500 of these
little facets. The simple eyes are _myopus_, or short-sighted--the
compound eyes for more distant but perfect sight. They appear to have a
strong sense of smell. Many of them cannot swim, but walk with more or
less facility at the bottom of the water. It is said, for instance, that
the cavalier of the Syrian coast, _Oxypoda cursor_ (Fabricius), is named
from the rapidity with which it traverses great distances.

Many systems have been proposed by different writers for the arrangement
of the Crustacea. That proposed by Mr. Milne Edwards recommends itself,
being founded on anatomical examination and actual experiment made by
himself and M. Audouin. He divides them into two great divisions: I.
Those in which the mouth is furnished with a certain number of organs
adapted for the prehension or division of food. II. Those in which the
mouth is surrounded by ambulatory extremities, the bases of which
perform the part of jaws. The first includes the MAXILOSA or
MANDIBULATA, again divided into _Decapoda_, having branchiæ attached to
the sides of the thorax, and enclosed in special cavities. The
_Decapoda_ are divided into: 1. BRACHYURA, namely, the Crabs. _Cancer_,
_Porlunus_, _Grapsus_, _Ocypode_, and _Doippe_, belong to this group. 2.
ANOMOURA, including _Droma_, _Pagurus_, _Porcellana_, and _Hippa_. 3.
MACROURA, including the Lobsters, _Astacus_, _Palæmon_, the Craw-fish,
_Palinurus_.

_Stomatopoda_, with external branchiæ, sometimes rudimentary, sometimes
none. Thoracic extremities prehensile, or for swimming generally, six or
eight pairs. This division includes Mysids, Phyllosoma, Squilla, &c.

The Cirripedia, or barnacles, are a very important division of
Crustacea; they are found in all seas, and attach themselves to almost
every object in the sea; from the immovable rock to the moving animal;
from the little Tunicata to the great turtle, or the whale.

The goose barnacles, _Anatifa_, have a flexible peduncle. The
Balanoidea, or sea acorns, like oysters, are rooted to the spot on which
they rest in their infant days; without the power, like the goose
barnacle, of swaying to and fro like a pendulum, be their resting-place
what it may.

One of the most remarkable animals of this class of Crustacea is the
_Limulus Moluccanus_--the Molucca crab. They are distinguished by a long
serrated spine, which looks most formidable. They are in great request
in the markets of Java. Linnæus thought that the fossil trilobites were
closely allied to the _Limulus_. Latreille, on the contrary, classed
them near the mollusc, chiton. The tail of _Limulus_ so strikingly
resembles that of many Trilobites, that the most common observers may
perceive an affinity.


CRABS AND CRAW-FISH.

Crabs and lobsters may be regarded as the chiefs or lords of the
Crustacean tribes. The crabs have very large claws and smooth backs; the
last have small claws and the back covered with spines. Tiberius Cæsar
had the face of a poor fisherman scratched by the rugged shell of a
craw-fish.

Lobsters, especially, have an amazing fecundity, and yield an immense
number of eggs, each female producing from 12,000 to 20,000 in the
season. The crab is also very prolific. These eggs are, in the lobster,
arranged in packets, which are attached to the lower surface of the
tail, to which they are connected by a viscous substance. The manner in
which the female lobster disposes of her burden is curious and
interesting. Whether she bends or stands erect she is able to hold it
obscurely or expose it to the light. Sometimes, according to Coste, the
eggs are left immovable, or simply submerged; at others they are
subjected to successive washings by gently agitating the false claw
which shelters them from right to left. When first exuded from the ovary
the eggs are very small, but they seem to increase during the time they
are borne about under the tail, and before they are committed to the
sand or water they have attained the size of small shot. The evolution
of the germ is in progress during six months. At the moment of exclusion
the female extends the tail, impresses upon the eggs an oscillating
motion, in order to destroy the shell and scatter the larvæ, delivering
herself in two or three days of her entire burden (Coste). "As the young
lie enclosed within the membrane of the egg," says Couch, "the claws are
folded on each other, and the tail is flexed on them as far as the
margin of the shield. The dorsal spine is bent backwards, and lies in
contact with the dorsal shield, for the young when it escapes from the
egg is quite soft; but it rapidly hardens and solidifies by the
deposition of calcareous matter on what may be called its skin."

[Illustration: Fig. 333. Palinurus vulgaris. _a_, left outward
jaw-foot.]

As soon as born, the young Crustaceans withdraw from the mother and
ascend to the surface of the water, in order to gain the open sea. They
swim in a circle; but this pelagic life is not of long duration; they
quit it after their fourth moult, which takes place between the
thirtieth and fortieth day, at which time they lose the transitory
organs of natation which they have hitherto possessed. After this they
are no longer able to maintain themselves on the surface, but drop to
the bottom. Henceforth they are condemned to remain there, and such
walking as they can exercise becomes their habitual mode of
progression. As they increase in size they gradually approach the
shore, which they had for the moment abandoned, and return to the places
inhabited by the parent Crustaceans.

The form of the larvæ differs so much from that of the adult, that it
would be difficult, except on the clearest evidence, to determine the
species from which they proceed. Former naturalists considered the
embryo cray-fish (_Palinurus_) to belong to a distinct genera, which
they designated _Phyllosoma_. It is now known, however, that these are
the young of the higher forms of Crustaceans undergoing metamorphosis.
In the various forms of _Macroura_ the metamorphosis is less decided
than in the _Brachyura_. In the fresh-water cray-fish no change whatever
takes place. Dissatisfied with the uncertainty of former experiments,
Mr. Couch undertook a series of observations, which are recorded in the
proceedings of the Cornwall Polytechnic Society, in which he established
the fact that metamorphosis takes place in the following genera: Cancer,
Xanthò, Plumnus, Carcinus, Portunus, Maja, Galathea, Hornarus, and
Palinurus. "Metamorphosis has been demonstrated," says Dr. Bell, "in no
less than seventeen genera of the Brachyurous order of Decapoda, in
which it is most decided and obvious; in Leptopodia, Majacea, Cancer,
Portunidæ, Pinnoteres, and Grapsus. In the Anomourous order it is seen
in the Pagurus, Porcellana, and Galathea; and in the Macrouran order in
Homarus, Palinurus, Palæmon, and Crangon."

[Illustration: Fig. 334. Portunus variegatus, male.

_a_, external antenna; _b_, external jaw-foot; _c_, tail or abdomen.]

The swimming of these creatures is produced by flexions and expansions
of the tail, and by repeated beating motions of the claws, the tail
acting as a sort of vibratile oar, aided by which they maintain
themselves in the water and facilitate their progress. As the shell
becomes more solid they get less active, and finally return to the
bottom to cast their shell and assume a new form.

According to the observations of M. Coste, the young lobster casts its
shell from eight to ten times in the first year, from five to seven in
the second, three to four times the third, and two or three times the
fourth year. In the fifth year they attain the adult state. Whence it
follows, that the small lobsters served at our tables have changed their
calcareous vestment something like twenty-one times, and are now clothed
in their twenty-second habit.

[Illustration: Fig. 335. Corystes Cassivelaunus, male.]

The crabs are numerous in species and various in size. The long-clawed
crab (_Corystes Cassivelaunus_) of Pennant and Leach (Fig. 335) is
remarkable for its long antennæ, which considerably exceed the body. The
jaw-feet have their third joint longer than the second, terminating in
an obtuse point, with a notch on its interior edge; eyes wide apart,
borne upon large peduncles, which are nearly cylindrical and short;
anterior feet large, equal, twice the length of the body, and nearly
cylindrical in the males; in the females (Fig. 336) about the length of
the body, and compressed, especially towards the hand-claw. The other
feet terminate in an elongated nail or claw, which is straight-pointed
and channeled longitudinally: carapace oblong-oval, terminating in a
rostrum anteriorly truncated and bordered posteriorly; the regions but
slightly indicated, with the exception of the cordian region, the
branchial or lateral regions being very much elongated.

[Illustration: Fig. 336. Corystes Cassivelaunus, female.]

Latreille gives the name of Corystes, which signifies a warrior armed,
to this genus of Crustaceans, from κόρυς, a helmet, but it is
perfectly inoffensive. Pennant had already conferred the name of
_Cassivelaunus_, the chief of the Ancient Britons, for the singular
reason, according to Gosse, that the carapace, which is marked by
wrinkles, bears, in old males especially, the strongest and most
ludicrous resemblance to the face of an ancient man. Pennant's
well-known sympathy with his British ancestry certainly never led him
to caricature the grand old British warrior, as Mr. Gosse surmises. On
the contrary, he saw in the Crustacean a creature armed at all points,
and he named it after the hero of his imagination.

In this species the surface of the carapace is somewhat granulous, with
two denticles between the eyes, and three sharp points directed forward
on each side. The male has only five abdominal pieces, but the vestiges
of the separation of the two others may be clearly remarked upon the
outer mediate or third piece, which is the largest of all. The length of
the antennæ is remarked on by Mr. Couch, in his Cornish Fauna. "These
organs," he says, "are of some use beyond their common office of
feelers; perhaps, as in some other Crustaceans, they assist in the
process of excavation; and, when soiled by labour, I have seen the crab
effect their cleaning by alternately bending the joints of their stalks,
which stand conveniently angular for the purpose. Each of the long
antennæ is thus drawn along the brush that fringes the internal face of
the other, until both are cleared of every particle that adhered to
them." On the other hand, Mr. Gosse suggests that the office of the
antennæ is to keep a passage open for ejecting the deteriorated water
after it has bathed and aerated the gills. "I have observed," he says,
"that, when kept in an aquarium, these crabs are fond of sitting bolt
upright, the antennæ placed close together, and pointing straight
upwards from the head. This is doubtless the attitude in which the
animal sits in its burrow, for the tips of the antennæ may often be seen
just projecting from the sand. When the chosen seat has happened to be
so close to the glass side of the tank as to bring the antennæ within
the range of a pocket lens, I have minutely investigated these organs
without disturbing the old warrior in his meditation. I saw on each
occasion that a strong current of water was continuously pouring up from
the points of the antennæ. Tracing this to its origin, it became evident
that it was produced by the rapid vibration of the foot-jaws drawing in
the surrounding water, and pouring it off upwards _between the united
antennæ_, as through a tube. Then, on examining these organs, I
perceived that the form and arrangement of their bristles did indeed
constitute each antennæ a semi-tube, so that when the pair were brought
face to face the tube was complete."

Among the numerous genera of _Brachyurous Crustaceans_, Grapsus is
distinguished by its less regularly quadrilateral form; the body nearly
always compressed, and the sternal plastron but little or not at all
curved backwards; the front strongly recurved, or, rather, bent
downwards; the orbits oval-shaped and of moderate size; the lateral
edges of the carapace slightly curving and trenchant; the ocular
pedicles large, but short: their insertion beneath the front and the
cornea occupies one-half of their length.

[Illustration: Fig. 337. Pagurus Bernhardus. 1, out of the shell; _a_,
right jaw-foot; _b_, in the shell.]

The Hermit or Soldier Crab (_Pagurus Bernhardus_, Fabricius, Fig. 337)
is, perhaps, the oddest and most curious of Crustaceans. It differs from
most other Crustaceans in this: in place of having the body protected by
a calcareous armour, more or less thick and solid, it has only a
cuirass and head-piece to protect the head and breast; all the rest of
the body is invested in a soft yielding skin; and this, the vulnerable
part of the hermit crab, is the delicate morsel devoured by the gourmet.
Nor is our somewhat evil-disposed Crustacean ignorant of the perfectly
weak and defenceless state of its posterior quarters. Prudence or
instinct makes it seek the shelter of some empty shell, of a shape and
size corresponding to its own. When it fails to find one empty, it does
not hesitate to attack some living testacean, which it kills without
pity or remorse, and takes possession of its habitation without other
form of process. Once master of the shell (Fig. 337), it introduces
itself, stern foremost, and installs itself as in an entrenchment, where
it is established so firmly that it moves about with it more or less
briskly, according to its comparative size.

The Pagurians belong to the Anomourous family of Crustaceans, of which
there are several genera, and a considerable number of species, the
animal economy of which has been ably commented upon by Mr. Broderip.
"Their backs," he says, "are towards the arch of the turbinated shell
occupied by them, and their well-armed nippers and first two pairs of
succeeding feet generally project beyond the mouth of it. The short feet
rest upon the polished surface of the columella, and the outer surface
of their termination, especially that of the first pair, is in some
species most admirably rough-shod, to give 'the soldier' a firm footing
when he makes his sortie, or to add to the resistance of the crustaceous
holders at the end of his abdomen, or tail, when he is attacked, and
wishes to withdraw into his castle. On passing the finger downwards over
the terminations of these feet, they feel smooth; but if the finger be
passed upwards, the roughness is instantly perceived. The same sort of
structure (it is as rough as a file) is to be seen in the smaller caudal
holders." In another species of Pagurus, from the Mauritius, which was
nearly a foot in length, he found a great number of transverse rows,
armed with acetabula, or suckers; these were visible without the aid of
a glass, which must very much assist the hold of the _Pagurus_.

During the feeding and breeding-time, the hermit throws out his head and
feet, and especially his great claws, and feels his way with his two
antennæ, which are long and slender. When he walks he hooks on with his
pincers to the nearest body, and draws his shell after him, as the snail
does his. But the undefended parts of the body always remain under
cover. At low water the hermits spread themselves over the rocky shore,
and the spectator thinks he sees a great number of shells which move in
all directions, with allurements different from that which belongs to
their essentially slow and measured race. If they are touched they stop
suddenly, and it is soon discovered that their shell is the dwelling of
a crustacean, not a mollusc. The animal lives alone in its little
citadel, like the hermit in his cell or the sentinel in his box. Hence
the name of _hermit_ and _soldier_.

When our crustacean outgrows its borrowed habitation, it sets out in
search of another shell, a little larger, and better suited for its
increased size.

The hermit often avails itself, as we have said, of empty shells
abandoned by their owners; when the tide retires these seldom fail them,
and the hermit may be seen examining, turning, and returning, and even
trying its new domicile. It glides slowly along on its abdomen, which is
large and somewhat distorted, sometimes in one shell, sometimes in
another, looking defiantly all round it, and returning very quickly to
its ancient lodging if the new one does not turn out to be perfectly
comfortable, often trying a great number, as a man might try many new
clothes before suiting himself. In its successive removals the little
sybarite chooses a hermitage more and more spacious, according to its
taste or caprice in colour or architecture. The cunning little creature
chooses its mansion, now grey or yellow, now red or brown, globular or
cylindrical, in the form of a spiral or of a tun, toothed or crenulate,
with trenchant edge or pointed terminations; but, as a rule, our
crustacean Diogenes houses itself in spirals of considerable length, as
in _Cerithium_, _Buccinum_, or _Murex_.

The hermit is very timid; at the least noise it shrinks into its shell
and squats itself, without motion, drawing in its smaller claws and
closing the door with its larger ones, the latter being often covered
with hairs, tubercles, or with teeth. In short, our prudent cenobite
clings so closely to the bottom of its retreat, that we might pull it to
pieces without getting it out entire; its tail is transformed into a
sort of sucker, by the aid of which it attaches itself firmly to the
walls of its habitation. It is at once strong and voracious, eating with
much relish the dead fishes and fragments of molluscs and annelids which
come in its way. Nor does it hesitate to attack and devour living
animals. When introduced into an aquarium, it has sometimes thrown it
into the utmost disorder by its insatiable rapacity. It has been
possible sometimes to preserve harmony among many individuals inhabiting
the same reservoir; but this has been owing rather to the impossibility
of their attacking each other, in consequence of cunningly-devised
barricades, than to their mildness of character or love of their
neighbour. These animals, in short, are very quarrelsome. Two hermits
cannot meet without showing hostility; each extends his long pincers,
and seems to try to touch the other, much as a spider does when it seeks
to seize a fly on its most vulnerable side; but each, finding the other
armed in proof, and perfectly protected, though eager to fight, usually
adopts the better part of valour, and prudently withdraws. They often
have true passages of arms, nevertheless, in which claws are spread out,
and displayed in the most threatening manner; the two adversaries
tumbling head over heels, and rolling one upon the other, but they get
more frightened than hurt. Nevertheless, Mr. Gosse once witnessed a
struggle which had a more tragic end. A hermit crab met a brother
Bernhard pleasantly lodged in a shell much more spacious than his own.
He seized it by the head with his powerful claws, tore it from its
asylum with the speed of lightning, and took its place not less
promptly, leaving the dispossessed unfortunate struggling on the sand in
convulsions of agony. "Our battles," says Charles Bonnet, "have rarely
such important objects in view: they fight each other for a house."

A pretty little zoophyte, the Cloak Anemone (_Adamsia palliata_), loves
to live with the hermit, and exhibits sympathies almost inexplicable. In
aquariums this anemone attaches itself almost always to the shell which
serves as the dwelling of the Crustacean; and it may be looked upon as
certain that where the hermit is there will the anemone be found. These
two creatures seem to live in perfect and intelligent harmony together,
for Mr. Gosse's observations establish the existence of a cordial and
reciprocal affection between them. This learned and intelligent observer
describes the proceedings of a hermit which required a new habitation;
he saw it detach, in the most deliberate but effective manner, its dear
companion, the anemone, from the old shell, transport it with every care
and precaution, and place it comfortably upon the new shell, and then
with its large pincers give to its well-beloved many little taps, as if
to fix it there the more quickly. Another species of Bernhardus makes a
companion of the _mantled anemone_. "And we are assured," says
Moquin-Tandon, "that when the crab dies its inconsolable friend is not
long in succumbing also."

"Is there not here much more than what our modern physiologists call
automatic movements, the results of reflex sensorial action?" says
Gosse. "The more I study the lower animals, the more firmly am I
persuaded of the existence in them of psychical faculties, such as
consciousness, intelligence, skill, and choice; and _that_ even in those
forms in which as yet no nervous centres have been detected."


LOBSTERS.

In a dietary, as well as commercial sense, the lobster far excels the
crab; like the latter, they have an amazing fecundity, each female
producing from twelve to twenty thousand eggs in a season; and wisely is
it so arranged, otherwise the consumption would soon exhaust them.

In France the size of the marketable lobster is regulated by law, and
fixed at twenty centimètres (eight inches) in length; all under that
size are contraband. Every year the inhabitants of Blainville proceed to
Chaussey to fish for lobsters. They are taken in baskets in the form of
a truncated cone, the mouth of which is so arranged that the animal can
enter, but cannot get out. The numbers caught by each fisherman and his
family in a season may be estimated at a thousand or twelve hundred,
which realise to the family thirteen or fourteen hundred francs, the
season lasting about nine months.

Lobsters are collected all round our own coast for the London market. On
the Scottish shore they are collected and kept in perforated chests
floating on the water, until they can be taken away to market. From the
Sutherland coast alone six to eight thousand lobsters are collected in a
season. This process goes on all round the coast, and as far as Norway,
whence an enormous supply of the finest lobsters are obtained, for which
something like £20,000 per annum is paid, all these contributions being
conveyed to the Thames and Mersey in welled vessels. But these
old-fashioned systems are being rapidly superseded by the construction
of artificial storing ponds, or basins. Of these ponds Mr. Richard
Scovell has erected one at Hamble, near Southampton, in which he can
store with ease fifty thousand lobsters, which will keep in good
condition for six weeks. Mr. Scovell's tank is supplied from the coasts
of France, Scotland, and Ireland, where fine lobsters abound. He employs
three large and well-appointed smacks, each of which can carry from five
thousand to ten thousand. On the coast of Ireland alone, it is said, ten
thousand fine lobsters a week might be taken.

The Lobster (_Homarus_) is found in great abundance all round our coast;
frequenting the more rocky shores and clear water, where it is of no
great depth, about the time of depositing its eggs. Various are the
modes in which they are taken; cone-shaped traps made of wicker-work,
and baited with garbage, are perhaps the most successful. These are sunk
among the rocks, and marked by buoys. Sometimes nets are sunk, baited by
the same material. In other places a wooden instrument, which acts like
a pair of tongs, is used for their capture.

Mr. Pennant, the naturalist, paid great attention to the lobsters, and
their habits are well described in a letter from Mr. Travis, of
Scarborough. "The larger ones," he says, "are in their best season from
the middle of October to the beginning of May. Many of the smaller ones,
and some few of the larger individuals, are good all the summer. If they
are four and a half inches long from the top of the head to the end of
the back shell, they are called sizeable lobsters; if under four inches,
they are esteemed half size, and two of them are reckoned for one of
size. Under four inches they are called pawks, and these are the best
summer lobsters. The pincers of one of the lobster's large claws are
furnished with knobs, while the other claw is always serrated. With the
former it keeps firm hold of the stalks of submarine plants; with the
latter it cuts and masticates its food very dexterously. The knobbed or
thumb claw, as the fishermen call it, is sometimes on the left,
sometimes on the right side, and it is more dangerous to be seized by
the serrated claw than the other."

There is little doubt that the lobsters cast their shell annually, but
the mode in which it is performed is not satisfactorily explained. It is
supposed that the old shell is cast, and that the animal retires to some
lurking-place till the new covering acquires consistence to contend with
his armour-clad congeners. Others contend that the process is one of
absorption, otherwise, if there were a period of moult, it would be
shown by their shells. The most probable conjecture is that the shell
sloughs off piecemeal, as it does in the cray-fish. The greatest mystery
of all, perhaps, is the process by which the lobster withdraws the
fleshy part of its claws from their calcareous covering. Fishermen say
the lobster pines before casting its shell, so as to permit of its
withdrawing its members from it.

The female lobster does not seem to cast her shell the same year in
which she deposits her ova, or, as the fishermen say, "is in berry."
When the ova first appear under the tail, they are small and very black,
but before they are ready for deposition they are almost as large as
ripe elderberries, and of a dark-brown colour. There does not seem to be
any particular season for this act, as females are found in berry at all
seasons, but more commonly in winter. In this state they are found to be
much exhausted, and by no means fit for the table.

[Illustration: Fig. 338. Nephrops Norvegicus.]

The generic name, _Astacus_ of Fabricius, is now confined to the
crawfishes, which have a depressed rostrum, one tooth on each side, and
the last ring of the thorax movable. The lobsters (_Homarus_) have the
eyes spherical, two rings of the thorax being soldered together. The
Norway Lobsters (_Nephrops Norvegicus_, Fig. 338) have the eyes uniform,
and the two last rings of the thorax movable.

The last is one of the most beautiful of the larger Macrourans. Its
general tint is pale flesh colour, with darker shades in parts, its
pubescence light brown. This is generally considered a northern species,
but Mr. Bell states that he has received specimens from the
Mediterranean. It is found plentifully on the coast of Norway, on the
Scottish coast, and in the Bay of Dublin. It is considered the most
delicate of all the Crustaceans.

[Illustration: Fig. 339. Crangon vulgaris, _a_, Anterior foot or claw.]

Before concluding this chapter, we perhaps should not omit brief notices
of the common prawn (_Palæmon serratus_) and the shrimp (_Crangon
vulgaris_), as types of an extensive variety of form of crustacea, which
inhabit all seas, and which perform important functions as regards the
sanitary state and economic condition of the waters of the ocean. These
small animals are the scavengers of the sea--they pick up and devour all
dead matter, leaving (it may be) a clean skeleton, without a shred of
fibre behind. In this respect they resemble the ants on land, doing
their work always thoroughly and effectively. We need hardly mention,
what is so well known to every reader, that prawns and shrimps are
amongst the most esteemed delicacies at our table, and as articles of
food occupy no mean place on the fish-stall. At Billingsgate alone, it
is hardly credible the immense quantities which arrive and are daily
consumed in the Metropolis by all classes of the