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Title: The Sea-beach at Ebb-tide - A Guide to the Study of the Seaweeds and the Lower Animal - Life Found Between Tide-marks
Author: Arnold, Augusta Foote
Language: English
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*** Start of this LibraryBlog Digital Book "The Sea-beach at Ebb-tide - A Guide to the Study of the Seaweeds and the Lower Animal - Life Found Between Tide-marks" ***
THE
SEA-BEACH AT EBB-TIDE
THE
SEA-BEACH AT EBB-TIDE
A GUIDE TO THE STUDY OF
THE SEAWEEDS AND THE
LOWER ANIMAL LIFE FOUND
BETWEEN TIDE-MARKS
BY
AUGUSTA FOOTE ARNOLD
WITH MORE THAN
600 ILLUSTRATIONS
[Illustration]
NEW YORK
THE CENTURY CO.
1901
And hath been tutor'd in the rudiments
Of many desperate studies.
SHAKSPERE.
Copyright, 1901, by
THE CENTURY CO.
/Published May, 1901/
THE DE VINNE PRESS.
PREFACE
This volume is designed to be an aid to the amateur collector and
student of the organisms, both animal and vegetable, which are found
upon North American beaches. In it are described many invertebrates
and some of the more notable varieties of seaweeds, and each
individual is given its proper place in the latest classification.
The technicality of classification or scientific grouping may at
first seem repellent, but it in reality makes the study of these
objects more simple; and a systematic arrangement has been adopted in
the belief that it is the easiest as well as the only satisfactory
way of becoming familiar with the organisms described. Without it
a very confused picture of separate individuals would be presented
to the mind, and a book like the present one would become a mere
collection of isolated scraps of information. Morphology, or the
study of structure, has been touched upon just enough to show the
objects from the biologist's point of view and to enable the observer
to go a little beyond the bare learning of names.
Scientific names have been used from necessity, for the plants
and animals of the beach are so infrequently observed, except by
scientific people, that but few of them have common names; and, as
a matter of fact, the reader will find that a scientific name is
as easily remembered as a common one. Technical phraseology has,
however, been avoided as much as possible, even at the expense of
conciseness and precision; where it has been used, care has been
taken to explain the terms so that their meaning will be plain to
every one. A general glossary has been omitted, but the technical
terms used have been indexed. The illustrations will bear the use of
a hand-glass, and this will often bring out details which cannot well
be seen by the unaided eye.
The systematic table of the marine algæ, as given in Part I, and
followed in the text, will be of use to collectors who wish to make
herbaria. In order to name and group specimens such a guide is
necessary. Should specific names lead to embarrassment, many of them
can be neglected, for the names of genera are often a sufficient
distinction.
Since so many species of invertebrates are found on the beach that
a complete enumeration of them is impracticable, only the most
conspicuous ones have been selected for description in Part II;
but the attempt has been made to designate the various classes and
orders with sufficient clearness to enable the collector to identify
the objects commonly found on the shore, and to follow the subject
further, if he so desires, in technical books.
It is hoped that this book will suggest a new interest and pleasure
to many, that it will encourage the pastime of collecting and
classifying, and that it will serve as a practical guide to a
better acquaintance with this branch of natural history, without
necessitating serious study. Marine organisms are interesting
acquaintances when once introduced, and the real purpose of the
author is to present, to the latent naturalist, friends whom he will
enjoy.
Grateful acknowledgment is here made to the following persons who
have kindly assisted and advised the author and have also extended
valued courtesies to her in the preparation of this book: Smith Ely
Jelliffe, M.D., Ph.D.; Herbert M. Richards, A.B., Ph.D., Professor
of Botany in Barnard College; Marshall A. Howe, A.B., Ph.D.; the
Rev. George A. Holst; the Long Island Historical Society of Brooklyn
for the use of its fine herbarium, containing the collections of
Mr. John Hooper, Mr. A. R. Young, and others, from which most of
the illustrations of algæ in this book were photographed; Miss
Toedtleberg, Librarian of the Long Island Historical Society; Miss
Ingalls, in charge of the Museum of the Long Island Historical
Society; Dr. Theodore Gill; James A. Benedict, Ph.D., Assistant
Curator of Marine Invertebrates in the Smithsonian Institution; Miss
Mary J. Rathbun, second Assistant Curator of Marine Invertebrates in
the Smithsonian Institution; Miss Harriet Richardson; and especially
to Mr. John B. Henderson, Jr.
* * * * *
Thanks, also, are due to Messrs. Macmillan & Co. for permission to
use cuts from the "Cambridge Natural History," Parker and Haswell's
"Zoölogy", and Murray's "Introduction to the Study of Seaweeds";
to Swan Sonnenschein & Co. for the use of cuts from Sedgwick's
"Student's Text-book of Zoölogy"; to Wilhelm Engelmann for a cut from
"Die natürlichen Pflanzenfamilien" of Engler and Prantl; to Little,
Brown & Co. for permission to reproduce illustrations from Agassiz's
"Contributions to the Natural History of the United States"; to Henry
Holt & Co. for a cut from McMurrich's "Invertebrate Morphology";
to Houghton, Mifflin & Co. for cuts from the "Riverside Natural
History" and Agassiz's "Seaside Studies in Natural History"; to the
Commonwealth of Massachusetts for the use of illustrations from
Verrill's "Report upon the Invertebrate Animals of Vineyard Sound
and the Adjacent Waters," Gould's "Invertebrata of Massachusetts"
(ed. Binney), and certain fisheries reports; and to the United
States government for illustrations taken from Bulletin 37 of the
Smithsonian Institution and from reports of the United States Fish
Commission.
CONTENTS
INTRODUCTION
PAGE
I Signs on the Beach 1
II Collecting 6
III Classification 19
IV Animal Life in its Lowest Forms 21
V Distribution of Animal Life in the Sea 23
VI Some Botanical Facts about Algæ 25
VII Naming of Plants 28
VIII Distribution of Algæ 30
IX Some Peculiar and Interesting Varieties of Algæ 32
X Uses of Algæ 37
XI Collecting at Bar Harbor 40
PART I
MARINE ALGÆ
I BLUE-GREEN SEAWEEDS 47
(CYANOPHYCEÆ)
GRASS-GREEN SEAWEEDS 47
(CHLOROPHYCEÆ)
II OLIVE-GREEN AND BROWN SEAWEEDS 61
(PHÆOPHYCEÆ)
III RED SEAWEEDS 75
(RHODOPHYCEÆ OR FLORIDEÆ)
PART II
MARINE INVERTEBRATES
I PORIFERA (SPONGES) 99
II CŒLENTERATA (POLYPS) 111
III WORMS 159
(PLATYHELMINTHES, NEMATHELMINTHES, ANNULATA)
IV MOLLUSCOIDA 187
V ECHINODERMATA 199
VI ARTHROPODA 237
VII MOLLUSCA 299
VIII CHORDATA 471
INDEX 479
INTRODUCTION
In vain through every changeful year
Did nature lead him as before;
A primrose by a river's brim,
A yellow primrose was to him,
And it was nothing more.
At noon, when by the forest's edge
He lay beneath the branches high,
The soft blue sky did never melt
Into his heart; he never felt
The witchery of the soft blue sky.
WORDSWORTH.
To him who in the love of Nature holds
Communion with her visible forms, she speaks
A various language.
BRYANT.
INTRODUCTION
I
SIGNS ON THE BEACH
The sea-shore, with its stretches of sandy beach and rocks, seems,
at first sight, nothing but a barren and uninteresting waste, merely
the natural barrier of the ocean. But to the observant eye these
apparently desolate reaches are not only teeming with life; they are
also replete with suggestions of the past. They are the pages of a
history full of fascination for one who has learned to read it.
In this history even the grains of sand have a part. Though so humble
now, they once formed the rocky barriers of the shore. They stood
as do the rocks of to-day, defiant and seemingly everlasting, but
the fury of the sea, which knows no invincible adversary, has laid
them low. Every coast-line shows the destructive effects of the sea,
for the bays and coves, the caves at the bases of the cliffs, the
buttresses, stocks, needles, and skerries, are the work of the waves.
And this work is constantly going on.
Even a blind man could not stand long upon a shingly beach without
knowing that the sea was busily at work. Every wave that rolls
in from the open ocean hurls the pebbles up the slope of the
beach, and then as soon as the wave has broken and the water has
dispersed, these pebbles come rattling down with the currents that
sweep back to the sea. The clatter of the beach thus tells us
plainly that as the stones are being dragged up and down they are
constantly knocked against each other; and it is evident that by
such rough usage all [pg002] angular fragments of rock will soon
have their corners rounded off and become rubbed into the form of
pebbles. As these pebbles are rolled to and fro upon the beach they
get worn smaller and smaller, until at length they are reduced
to the state of sand. Although this sand is at first coarse, it
gradually becomes finer and finer as surely as though it were
ground in a mill; and ultimately it is carried out to sea as fine
sediment and laid down upon the ocean floor.[1]
[Footnote 1: Huxley.]
The story of the sands is not only one of the conflict of the sea
and rocks; it is also a story of the winds. It is the winds that
have rescued them from the waves and driven them about, sifting
and assorting them, arranging them in graceful forms, and often
heaping them up into dunes which, until fastened by vegetation, are
themselves ever moved onward by the same force, sometimes burying
fertile lands, trees, and even houses in their march. The sands,
moreover, are in turn themselves destructive agents, to whose power
the many fragments which strew the beach and dunes bear ample
witness. The knotty sticks so commonly seen on the beach are often
the hearts of oak- or cedar-trees from which the tiny crystals of
sand have slowly cut away their less solid outer growth. Everything,
in fact, upon the sands is "beach-worn," even to the window-glass of
life-saving stations, which is frequently so ground that it loses its
transparency in a single storm.
The beach is also a vast sarcophagus holding myriads of the dead.
"If ghosts be ever laid, here lie ghosts of creatures innumerable,
vexing the mind in the attempt to conceive them." And there are
certain sands which may be said to sing their requiem, the so-called
musical sands, like the "Singing Beach" at Manchester-by-the-Sea,
which emit sounds when struck or otherwise disturbed. On some
beaches these sounds resemble rumbling, on others hooting; sometimes
they are bell-like and even rhythmical. The cause of this sonorous
character is not definitely known, but it is possibly due to films
of compressed gases which separate each grain as with a cushion, and
the breaking of which [pg003] causes, in the aggregate, considerable
vibrations. Such sands are not uncommon, having been recorded in
many places, and they exist probably in many others where they have
escaped observation. They may be looked for above the water-line,
where the sand is dry and clean.
We have to do, however, in this volume, not with the history of the
past, nor with the action of physical forces, but with the life of
the present, and to find this, in its abundance, one must go down
near the margin of the water, where the sands are wet. There is no
solitude here; the place is teeming with living things. As each wave
retreats, little bubbles of air are plentiful in its wake. Underneath
the sand, where each bubble rose, lives some creature, usually a
mollusk, perhaps the razor-shell /Solen ensis/. By the jet of water
which spurts out of the sand, the common clam /Mya arenaria/ reveals
the secret of its abiding-place. A curious groove or furrow here and
there leads to a spot where /Polynices heros/ has gone below; and the
many shells scattered about, pierced with circular holes, tell how
/Polynices/ and /Nassa/ made their breakfast and their dinner. Only
the lifting of a shovelful of sand at the water's edge is needed to
disclose the populous community of mollusks, worms, and crustaceans
living at our feet, just out of sight.
Even the tracks and traces of these little beings are full of
information. What may be read in the track of a bird on the sand is
thus described by a noted ornithologist:
Here are foot-notes again, this time of real steps from real
feet. . . . The imprints are in two parallel lines, an inch or so
apart; each impression is two or three inches in advance of the
next one behind; none of them are in pairs, but each one of one
line is opposite the middle of the interval between two of the
other line; they are steps as regular as a man's, only so small.
Each mark is fan-shaped; it consists of three little lines less
than an inch long, spreading apart at one extremity, joined at
the other. At the joined end, and also just in front of it, a
flat depression of the sand is barely visible. Now following the
track, we see it run straight a yard or [pg004] more, then twist
into a confused ball, then shoot out straight again, then stop,
with a pair of the footprints opposite each other, different from
the other end of the track, that began as two or three little
indistinct pits or scratches, not forming perfect impressions of a
foot. Where the track twisted there are several little round holes
in the sand. The whole track commenced and finished upon the open
sand. The creature that made it could not, then, have come out
of either the sand or the water; it must have come down from the
air—a two-legged flying thing, a bird. To determine this, and,
next, what kind of bird it was, every one of the trivial points of
the description just given must be taken into account. It is a bit
of autobiography, the story of an invitation to dine, acceptance,
a repast, an alarm at the table, a hasty retreat. A bird came on
wing, lowering till the tips of its toes just touched the sand,
gliding half on wing, half afoot, until the impetus of flight was
exhausted; then folding its wings, but not pausing, for already a
quick eye spied something inviting; a hasty pecking and probing to
this side and that, where we found the lines entangled; a short run
after more food; then a suspicious object attracted its attention;
it stood stock-still (just where the marks were in a pair), till,
thoroughly alarmed, it sprang on wing and was off.[2]
[Footnote 2: Elliott Coues.]
Following the key further, he draws more conclusions. The tracks are
not in pairs, so the bird does not belong to the perchers; therefore
it must be a wader or a swimmer. There are no web-marks to indicate
the latter; hence it is a three-toed walking or wading bird. It had
flat, long, narrow, and pointed wings because it came gliding swiftly
and low, and scraped the sand before its wings were closed. This
is shown by the few scratches before the prints became perfect. A
certain class of birds thus arrests the impetus of flight. It had a
long feeling-bill, as shown by the little holes in the sands where
the marks became entangled; and so on. These combined characteristics
belong to one class of birds and to no other; so he knows as
definitely as [pg005] though he had seen the bird that a sandpiper
alighted here for a brief period, for here is his signature.
It is plain that tracks in the sand mean as much to the naturalist as
do tracks in the snow to the hunter, and trails on the land to the
Indian who follows his course by signs not seen by an untrained eye.
The tide effaces much that is written by foot and wing, but sometimes
such signs are preserved and become veritable "footprints on the
sands of time." In the Museum of Natural History in New York is
a fossil slab, taken from the Triassic sandstone, showing the
footprints of a dinosaurian reptile now extinct, which, in that long
ago, walked across a beach—an event unimportant enough in itself,
but more marvelous than any tale of imagination when recorded for
future ages. From such tracks, together with fragments of skeletons,
the dinosaur has been made to live again, and its form and structure
have been as clearly defined as those of the little sandpiper of Dr.
Coues.
[pg006]
II
COLLECTING
It has been said that everything on the land has its counterpart
in the sea. But all land animals are separate and independent
individuals, while many of those of the sea are united into organic
associations comprising millions of individuals inseparably connected
and many of them interdependent, such as corals, hydroids, etc. These
curious communities can be compared only to the vegetation of the
land, which many of them resemble in outer form. Other stationary
animals, such as oysters and barnacles, which also depend upon
floating organisms for their food, have no parallel on the land.
The water is crowded with creatures which prey upon one another,
and all are interestingly adapted to their mode of life. Shore
species are exceedingly abundant, and the struggle for life is there
carried on with unceasing strife. In the endeavor to escape pursuers
while they themselves pursue, these animals have various devices of
armature and weapons of defense; they have keen vision, rapid motion,
and are full of arts and wiles. One of the first resources for safety
in this conflict is that of concealment. This is effected not only
by actual hiding, but very generally by mimicry in simulating the
color of their surroundings, and often by assuming other forms. Thus,
for instance, the sea-anemone when expanded looks like a flower and
is full of color, but when it contracts becomes so inconspicuous as
to be with difficulty distinguished from the rock to which it is
attached. Anemones also have stinging threads (nematophores), which
they dart out for further defense. [pg007]
The study of biology has great fascination, and the subject seldom
fails to awaken interest as soon as the habit of observation is
formed. Jellyfishes, hardly more dense than the water and almost as
limpid, swimming about with graceful motion, often illuminating the
water at night with their phosphorescence, showing sensitiveness,
volition, and order in their lives, cannot fail to excite wonder
in even the most careless observer. Not less interesting are the
thousands of other animals which crowd the shores, lying just beneath
the surface of the sand, filling crevices in the rocks, hiding under
every projection, or boldly—perhaps timidly, who shall say?—lying
in full view, yet so inconspicuous that they are easily passed by
unnoticed.
To find these creatures, to study their habits and organization, to
consider the wonderful order of nature, leads through delightful
paths into the realms of science. But even without scientific study
the simple observation of the curious objects which lie at one's feet
as one walks along the beach is a delightful pastime.
The features which separate the classes and the orders of both the
plant and the animal life are so distinctive that it requires but
very superficial observation to know them. It is easy to discriminate
between mollusks, echinoderms, and polyps, and to recognize the
relationship between univalves and bivalves, sea-urchins and
starfishes, sea-anemones and corals. The equally plain distinctions
between the branched, unbranched, tubular, and plate-like green algæ
make them as easy to separate.
The pleasure of a walk through field or forest is enhanced by knowing
something of the trees and flowers, and in the same way a visit to
the sea-shore becomes doubly interesting when one has some knowledge,
even though it be a very superficial one, of the organisms which
inhabit the shore.
ROCKY SHORES
Rocky shores furnish an abundance and great variety of objects to the
collector. The seaweeds here find places of attachment, and the lee
and crevices of the rocks afford shelter to many animals which could
not live in more open and exposed places. The [pg008] rock pools
harbor species whose habitat is below low-water mark and which could
not otherwise bear the alternation of the tides.
The first objects on the rocky beach to attract attention are the
barnacles and rockweeds. They are conspicuous in their profusion,
the former incrusting the rocks with their white shells, and the
latter forming large beds of vegetation; yet both are likely to be
passed by with indifference because of their plentifulness. They are,
however, not only interesting in themselves, but associated with
them are many organisms which are easily overlooked. The littoral
zone is so crowded with life that there is a constant struggle for
existence,—even for standing-room, it may be said,—and no class
of animals has undisputed possession of any place. Therefore the
collector should carefully search any object he gathers for other
organisms which may be upon it, under it, or even in it, such as
parasites, commensals, and the organisms which hide under it or
attach themselves to it for support. Let the rockweed (/Fucus/) be
carefully examined. Among the things likely to be found attached to
its fronds are periwinkles (/Littorina litorea/), which simulate
the plant in color, some shells being striped for closer mimicry.
Sertularian hydroids also are there, zigzagging over the fronds or
forming tufts of delicate horny branches upon them. Small jelly-like
masses at the broad divisions of the fronds may be compound
ascidians. Calcareous spots here and there may be polyzoans of
exquisite form, while spread in incrusting sheets over considerable
spaces are other species of /Polyzoa/. Tiny flat shelly spirals
are the worm-cases of /Spirorbis/. A pocket-lens is essential to
enable one to appreciate the beauty of these minute forms. Under the
rockweeds are many kinds of crustaceans; perhaps there will also be
patches of the pink urn-like egg-capsules of /Purpura/ at the base of
the fucus.
Various kinds of seaweed abound in the more sheltered parts of the
rocks, and among them will be found amphipods and isopods, many of
which are of species different from those of the sandy beaches. Here,
too, is the little /Caprella/, imitating the seaweed in form, and
swaying its lengthened body, which is attached to the plant only by
its hind legs. On the seaweeds, as well as in the tide-pool, may be
found beautiful hydroids, and on [pg009] them the curious little
sea-spiders (/Pycnogonidæ/), animals which seem to be all legs.
Mollusks, and other classes as well, differ in different latitudes.
On the rocks of the Northern shores /Littorina/ and /Purpura/ shells
are very abundant, the latter in various colors and beautifully
striped. Limpets are also plentiful, but are not as conspicuous,
since they have flat, disk-shaped shells. When their capture is
attempted, they must be taken unawares and pushed quickly aside,
else they take such a firm hold of the rock that it is difficult
to dislodge them. Near low-water mark under ledges will perhaps be
found chitons, which are easily recognized by their oval, jointed
shells. On the California coast in like localities will be found
the beautiful /Haliotis/, /Acmæa/, and chitons. Every stone that
is lifted will disclose numbers of little amphipods (/Gammarus/),
which will scuttle away on their sides to other shelter; worms will
suddenly disappear into the mud, and perhaps a crab, here and there,
having no alternative, will make a stand and fight for his liberty.
Flat against the stone and not easily perceived may be a chiton, a
planarian worm, or a nudibranch. And just below the water's edge are
sea-urchins and starfishes, which grow in numbers as the eye becomes
accustomed to the search.
The rock pools are natural aquaria, more interesting by far than any
prepared by man. The possibilities of these little sea-gardens are
beyond enumeration. The longer one studies them the more one finds.
In them all classes of seaweeds and marine invertebrates may be found
and their habits watched. The great beauty of these pools gives them
an esthetic charm apart from the scientific interest they excite.
Perhaps one may find here a sponge, and removing it to a shallow
vessel of sea-water can watch the currents of water it creates.
Several sponges of the same species placed in contact will at the
end of two days be closely united. If the sponges are of different
species they will not coalesce.
In the clefts and crannies of the rocks are various fine seaweeds,
often of the red varieties, sea-anemones, hydroids, polyzoans,
crustaceans, mollusks, and ascidians. Crabs will be snugly [pg010]
ensconced under projecting surfaces. Most species are more plentiful
at the lowest-water mark, and many are found only at this point and
below.
SANDY SHORES
On sandy shores the greater part of the inhabitants live under the
surface. Many give evidence of their presence by the open mouths of
their burrows, and some distinctly point out these places by piles
of sand or mud in coils at the opening. Some tubicolous worms have
their tubes projecting above the surface. The tubes of /Diopatra/
are hung with bits of shells, seaweeds, and other foreign matter.
Some mollusks announce themselves by spurting jets of water or
sending bubbles of air from the sand. The majority of the underground
species, however, give no sign of their presence on the surface,
and must be found by digging. Many of them go deep into the sand,
and in searching for worms the digger must be quick- and expert,
or he will lose entirely or cut in two many of the most beautiful
ones, which retreat quickly and to the extremity of their holes at
the least alarm. One can be a rambler on the sandy beach for a long
time without being aware of the many beautiful objects which inhabit
the subsurface of the sand. The curious crab /Hippa/ will disappear
so quickly into the sand that one is hardly sure he has really seen
it. The vast number of worms will surprise any one who searches for
them by their variety, their beautiful color, and their interesting
shapes. Here again a glass is requisite to appreciate the delicacy
and beauty of their locomotive organs, their branchiæ, and so on. The
most common of the gasteropod mollusks on sandy shores are /Nassa
obsoleta/, /Nassa trivittata/, and /Polynices (Lunatia) heros/. The
last are detected by the little mounds of sand which they push before
them as they plow their way just below the surface. On more southern
beaches, /Fulgur/, /Strombus/, and /Pyrula/ are the common varieties.
/Olivella/, /Oliva/, and /Donax/, also inhabitants of sandy beaches,
will quickly disappear when uncovered by the waves, being rapid
burrowers. Most of the many dead shells on the beach will be found
to be pierced with a round hole, which is [pg011] drilled by the
file-like tongue, or lingual ribbon, of /Polynices/, /Urosalpinx/,
or /Nassa/, which thus reach the animal within and suck out its
substance. Another similar species is /Polynices/ (/Neverita/)
/duplicata/, which extends to the Gulf of Mexico, while /P. heros/
is not commonly found below Hatteras. Crustaceans are abundant on
the sandy beach over its whole breadth. Some of the sand-crabs live
above tide-mark. Among these is the fleet-footed /Ocypoda/, which is
interesting to watch. Often they go in numbers to the water's edge
and throw up mounds, behind which they crouch like cats, watching
for whatever prey the tide may bring up. When unable to outrun a
pursuer they rush into the surf and remain there until the danger is
past. The wet sand is often thickly perforated with the burrows of
the sandhoppers (/Orchestia/). These often rise about the feet as do
grasshoppers in the fields.
[Illustration: PLATE I. Egg-capsules of Purpura lapillus. Egg-case of
Polynices heros. Egg-capsules of Buccinum undatum. Egg-case of the
skate. Fulgur canaliculata (whelk) and egg-cases.]
/Hippa talpoida/ is a remarkable crab, somewhat resembling an egg.
It is not likely to be seen unless searched for by digging at the
water's edge. It burrows so rapidly that one must be quick to catch
it after it is exposed by the shovel. In some places the tests of
"sand-dollars" are common. The living animal may be found buried just
below the surface at extreme low-water mark.
The sea-wrack drifted in lines along the shore will repay careful
examination, for here will be found many things belonging to other
shores and deep water. It is often alive with sandhoppers, which
hop away while one searches for less common things. Often the most
delicate seaweeds, numerous small shells, worms, polyzoans, etc.,
will be found there.
The surface of the sand-beach is strewn with remains of many species,
usually beach-worn, but interesting nevertheless as examples of
species one would like to find in better condition, but good
specimens of which elude ordinary search or are unobtainable except
by dredging.
Egg-cases form another class of objects which are often gathered with
no idea of their identity. Of these the most common are the long
strings of saucer-like capsules which contain the eggs of the mollusk
/Fulgur/, those having square edges being [pg012] the egg-cases of
/F. carica/, and those having sharp edges those of /F. canaliculata/.
Collar-like sandy rings contain the eggs of /Polynices/ (/Lunatia/),
which are cemented together in this shape. The boys of Cape Cod
call them "tommy-cod houses." Cylindrical piles of little capsules,
sometimes called "ears of corn," hold the eggs of /Chrysodomus/. The
irregular masses of small hemispherical capsules are those of the
common whelk (/Buccinum/). The so-called "Devil's pocket-books" are
the egg-cases of the skate.
MUDDY SHORES
On muddy shores the eel-grass (/Zostera marina/) grows abundantly,
giving an appearance of submerged meadows. It is one of the very
few flowering plants which live in salt water. In summer its little
green blossoms may be seen in grooves on the leaf-like blades. Many
animals live on and among eel-grass. Found upon it is the delicate
gasteropod mollusk /Lacuna vincta/, and its eggs in little rings; the
iridescent /Margarita helicina/, and /Nassa/, with its bright-yellow
eggs in small gelatinous masses; also little worms (/Spirorbis/) in
tiny flat spiral shells, compound ascidians in jelly-like masses,
clusters of shelly or horny polyzoans, isopods, planarian worms, and
so on. Scallops (/Pecten/) will be found at the base of the plants,
and the common prawns are very numerous, swimming freely about. Mud
flats and shores are the homes of many mollusks, especially of /Nassa
obsoleta/,—which is the most abundant shell of any considerable size
from Cape Cod to the Gulf of Mexico,—and of vast numbers of the tiny
/Littorinella minuta/, which serve as food for fishes and aquatic
birds. Clams and worms of all varieties are also abundant.
There are many varieties of mud-crabs, of which the most common
are the "fiddlers," which honeycomb the banks and the surface of
salt-marshes with their burrows. The common edible crab /Callinectes
hastatus/ is plentiful in bays and estuaries. The sluggish
spider-crabs hide beneath the surface of the mud and in decaying
weeds and eel-grass. Hermit-crabs are plentiful here as well as
elsewhere. /Panopeus/ is a sluggish crab found in shallow water and
in all sorts of hiding-places along the shore. It [pg013] may often
be found in dead shells, and, in the South, in holes in the banks.
This genus is represented by a number of species, some of which are
quite pretty.
WHARVES AND BRIDGES
On the piles of wharves and bridges may often be found beautiful
tubularian hydroids in large tufts just below low-water mark,
branched hydroids looking like little shrubs, polyzoans,
sea-anemones, mollusks, and ascidians. The species peculiar to these
localities are the boring mollusk /Teredo navalis/, or ship-worm, the
boring isopod /Limnoria lignorum/, and the boring amphipod /Chelura
terebrans/, all of which penetrate the wood and are most destructive.
The animals and plants of tropical beaches and coral reefs are
so various and abundant, so curious and beautiful, as to make
a description or even an enumeration of them in a brief space
difficult. The collector is bewildered and excited when he first
views the profusion of the wonderful forms there found.
It is not generally known that a fine species of "stony coral"
is common from Cape Cod southward, growing in clear water as an
incrustation on rocks, and developing little spires as it advances in
age. This species, the /Astrangia danaë/, is especially interesting,
since it will live in a dish of clear sea-water, and the polyps will
expand, showing a very close relationship to the sea-anemone. With
care in changing the water this coral will live for days, and may be
examined in its expanded condition with a lens of moderate power.
The most favorable time for collecting on any beach is at the lowest
tide, many objects being then uncovered which do not appear higher up
on the beach. At the spring-tides, which occur twice a month, at the
period of the new and that of the full moon, the ebb is especially
low, and affords an opportunity to search for forms whose habitat is
below ordinary low-water mark. During storms deep-water forms are
often torn from their beds and cast upon the beach. Shore-collecting
at these times is often very interesting. [pg014]
EQUIPMENT FOR COLLECTING INVERTEBRATES
The equipment for collecting upon sandy beaches is a shovel, a sieve,
and a net. Numerous trials should be made with the shovel from about
half-tide mark to as deep as one cares to wade, and the sand raised
should be carefully searched for shells, crustaceans, and worms.
By washing out the sand in the sieve the smallest specimens, which
might otherwise escape notice, may be secured. On a rocky beach a
strong knife and a net are sufficient. It is well to have a number
of homeopathic vials for small specimens, which will be injured
by contact with larger forms, and jars for holding the general
collection.
PRESERVING INVERTEBRATES
To preserve specimens, they should first be placed in a weak solution
of alcohol, the strength of which should be increased gradually until
the animal is entirely free from water and is hardened throughout.
If the alcohol becomes colored and sediment falls to the bottom
of the jar, the animal is degenerating, and the alcohol should be
changed. Specimens for transportation can be packed by wrapping each
one in a bit of cheese-cloth and then placing them together in a
large receptacle. Care should be taken to keep the fragile specimens
separate. Sand-dollars possess a pigment which discolors and soon
vitiates alcohol, and consequently these should be separated from
the other forms and placed where the alcohol may be changed from
time to time as appears necessary. The homeopathic vials containing
small specimens may be put into the can without injury to the other
specimens. Special cans of various sizes, with handles and screw
covers, are made for naturalists. One of these cans is a convenient
receptacle for carrying the alcohol to the station and for receiving
the collection for transportation. Careful notes should be made on
the spot of the conditions under which the species are found. One is
likely to forget details if this is delayed until one reaches home.
Labels should be used, giving name when known, or a number when the
name is not known, [pg015] corresponding with the note-book. Names
written with lead-pencil on a slip of paper will not be defaced by or
injure the alcohol. Collections when arranged permanently should be
placed in glass jars, the species being kept separate.
COLLECTING AND PRESERVING SEAWEEDS
To collect seaweeds one must search for them on rocks, in tide-pools,
in the sea-wrack upon the beach, on piles of wharves, on eel-grass,
and on the surface of incoming waves. It is well to follow the
receding tide and take advantage of its lowest ebb (especially of
that of the spring-tides, as mentioned above) to search the extreme
limit of the beach in the short time it is exposed. Many of the red
seaweeds are found there.
The equipment for collecting consists of a basket, two small tin
pails, one small enough to be carried within the other, a staff
with an iron edge at one end and a small net at the other, and a
pocket-lens. Rockweeds (/Fucus/) or other coarse gelatinous seaweeds
should be put into the basket. The pails, half filled with sea-water,
will receive the other specimens, fine and delicate algæ being put
into the smaller pail. It is well to have a second small receptacle
for /Callithamnion/ and /Griffithsia/, if one can be further
burdened. /Desmarestia/ should be kept apart, if possible, since it
discolors and decomposes other algæ; it should also have the earliest
attention when the time comes for mounting, and salt water should
be used for floating it upon the mount, otherwise the beauty of the
specimen will be impaired.
Besides its use as a support, the staff is needed to dislodge
specimens from the rocks, and the net to secure those that are
floating just out of reach. When possible, it is desirable to secure
the whole plant, including the holdfast, and to gather several
plants of the same species, since they vary with age and other
conditions, and it is also well to have duplicates for exchange. It
is particularly desirable to obtain plants which are in fruit. Each
specimen as it is taken should be rinsed in the sea-water to free it
from sand.
Collections should be mounted as soon as convenient, and [pg016]
especial care in this respect should be taken with red algæ, as they
decompose quickly. The requisites for mounting are blotters, pieces
of muslin, two or more smooth boards, weights, a basin, and several
shallow dishes containing water. Fresh water has a strong action on
the color and substance of seaweeds, and specimens should not be left
in it for any length of time.
Lift a specimen from the general collection, and in a basin of deep
water carefully wash off all superfluous matter; then place it in
shallow water and spread it out, trimming it judiciously, so that
when mounted it will not be too thick and the characteristics be
hidden. Specimens are more interesting and their species more easily
determined when laid out rather thin, showing their branching and
fruit. After the specimen is thus prepared, place it in a second
shallow dish of water. It should now be perfectly clean. Float it out
into the desired position, spreading it well, letting some parts show
the details of the branching, and other parts the general natural
effect of the mass. Run under it a rather heavy sheet of white paper,
and lift it carefully from the water. If raised from the center,
it is easier to let the water subside evenly and gradually without
disarranging the parts. Some collectors find it better to float the
specimen in water deep enough to allow the left hand to be placed
under the sheet to raise it. Lay the sheet on a plate, and with a
needle or forceps rearrange any of the delicate parts which have
fallen together. A few drops of water placed on any portion will
usually be sufficient to enable one to separate the branchlets or
ultimate ramifications. A magnifying-glass will be useful in this
work.
Cover a blotter with mounted specimens, spread over them a piece
of cotton cloth, and on this place another blotter, upon which lay
more mounted specimens and a cloth. Proceed in this way until all
the specimens are used. Lay the pile of blotters between boards, and
on them place the weights. The weights should not be very heavy.
Judgment must be used in assorting the specimens, those that are fine
being placed together. Those that are coarse and likely to indent
the blotters should be placed between separate boards. In this way a
flat surface and an even pressure will be obtained. The blotters and
cloths should be [pg017] changed twice each of the first two days,
then the cloths should be removed and the specimens left in press for
a week, the blotters being changed daily. Be sure that the specimens
are perfectly dry before placing them in the herbarium. Label each
specimen with the name and the date and place of collection.
There are some seaweeds which cannot be treated in the above manner.
/Fucus/ if placed in fresh water soon becomes slimy. It is so full of
gelatine that it soon destroys blotters; therefore it is well to hang
it up for several hours and then place it between newspapers, which
should be frequently changed, and as the plant becomes pliable it
should be arranged in proper position.
Those specimens which do not adhere to paper in drying should be
secured with gum. When it is impossible to mount specimens at the
time they are collected, they can be preserved by drying; afterward
they can be soaked and mounted in the usual manner. To dry the
plants, lay them separately upon boards without pressing out the
sea-water, and leave them in an airy, shaded place until thoroughly
dry; then pack them loosely into boxes and label, giving date and
locality. Blotters or driers can be obtained at botanical-supply
stores at thirty-five cents per quire.
HOW TO ARRANGE A HERBARIUM
The standard herbarium-paper is sixteen by eleven and a half
inches. The sheets are single, white, smooth, and quite heavy.
These, together with folded sheets of yellow manila paper, called
genus-covers, are the only requisites. It is desirable to have also
a case of shelves protected by glass doors. The shelves should be
twelve by eighteen inches, and four to six inches apart. They are
more convenient when made to slide like drawers.
The different species of one genus are gummed on one or more of the
white sheets and placed within the folded manila paper, which serves
as a cover. Each specimen should be signed with its name, place, and
date of collection, thus:
/C. rubrum./ Bar Harbor. Aug. 12, 1899,
the generic name being indicated by its initial capital letter and
the specific name written in full. To this are often added the
[pg018] name of the collector and some interesting comment. On the
lower left-hand corner of the genus-cover is written the generic name
in full and the species of that genus which the cover contains, thus:
/Ceramium/ /C. rubrum/
/C. strictum/
/C. diaphanum/
The genera of an order are then placed within a cover and labeled
in the same way, the legend then having the name of the order on
the left and the genera on the right of the bracket, [TN: see
Transcriber's Note.] thus:
/Rhodymeniaceæ/, suborder /Ceramieæ/
/Callithamnion/
/Griffithsia/
/Ceramium/
When the order is a large one the genera are distributed through as
many covers as may be necessary. The covers are then arranged on
shelves in the regular order of their classification, and each shelf
is labeled with the order it contains. Herbarium-sheets cost at
retail one dollar per hundred. Genus-covers cost at retail one dollar
and eighty cents per hundred. [pg019]
III
CLASSIFICATION
The first great biological division is into kingdoms, namely, the
animal kingdom and the vegetable kingdom. Then by classification the
vast number of existing animals and plants are grouped so as to give
each individual a definite place. By this system a beautiful order
is established, which enables the student to find any particular
animal or plant he may wish to study, and also to know its general
characteristics from the name of the group to which it belongs.
In broad generalization, objects of wide dissimilarity are recognized
as belonging to the same kingdom, as do trees and grasses, or as
do birds and fishes. Certain trees or grasses and certain birds or
fishes have such points of resemblance that they plainly show that
they belong to subdivisions. The most untutored people recognize
these distinctions, but the naturalist goes further and finds points
of distinction which the casual observer overlooks.
The animal kingdom has a varying number of divisions, called
/branches/, /subkingdoms/, or /phyla/. Some late authors have
admitted twelve divisions, and have given them the name /phyla/. Each
phylum is composed of a group of animals with a plan of structure
which is common to themselves, but differs from that of the animals
of all other phyla.
The higher animals begin with the twelfth phylum, namely, the
/Chordata/, or vertebrates. These animals have a spinal column, or
series of vertebræ, while the lower animals, or invertebrates are
without a spinal column, and depend for stability [pg020] upon
muscles or coriaceous or calcareous coverings. The vertebrates
are first represented in the fish-like forms. Bilateral symmetry,
however, or the uniform arrangement of parts on each side of
a central axis, exists in several groups which are below the
vertebrates, the first pronounced example being found in worms.
Groups lower than worms have their organs arranged around a central
axis or radiating from it, and were once all classed as /radiates/.
An animal is classified in accordance with its morphology, anatomy,
histology, and embryology. Morphology determines its general shape,
the position of its limbs, eyes, and mouth, and the covering of
its body; anatomy, the arrangement of its internal organs, such as
the position of its heart, lungs, stomach, etc.; histology, the
character of the tissues of the body; and embryology, the method of
the development of the animal from the embryo to maturity. It is only
after these exact discriminations have been made that the groups are
arranged. Owing to the greater accuracy resulting from histology and
embryology (methods which have been employed only in later years),
many changes in classification have been made, and as science
advances will continue to be made.
The primary groups are based on broad general characteristics,
but their divisions and subdivisions are determined by closer
distinctions. Animals having shells differ from those having a
cartilaginous or those having a crustaceous covering, and are placed
in different groups. Yet mollusks having a single or a double shell,
having spiral or flat forms, living on land, in fresh water, or in
the sea, while differing from one another, are all of one group.
Lobsters and crabs, although both have crustaceous coverings, are
very unlike; and again, there are many species of both lobsters and
crabs.
To group individuals, noting resemblances as well as differences,
a system of classification has been arranged with the following
divisions:
Kingdom, Phylum, Class, Order, Family (or Suborder), Genus, Species.
[pg021]
IV
ANIMAL LIFE IN ITS LOWEST FORMS
The biological division, or discrimination, between animal and
vegetable life, is based on the manner of assimilating food. Plants
feed upon mineral substances, or, in other words, assimilate
inorganic matter, while animal life requires for its support
vegetable or some other organic matter.
Animal as well as vegetable life in its lowest forms begins with
one-celled organisms, which are called respectively /Protozoa/ (first
animals) and /Protophyta/ (first plants). Both of these divisions
are composed mostly of microscopic objects, and, together with other
minute forms of life of the marine species, constitute a great part
of the /plankton/, or free-floating organisms of the sea. These
minute organisms seem like connecting-links between the two kingdoms.
They were claimed by both botanists and zoölogists until the use of
the microscope made close observation of minute structure possible.
Among the small animalcules of the phylum /Protozoa/ are some which
are familiar to all by name, such as the /Infusoria/, which are
most interesting creatures to examine in a drop of water under
the microscope. A more tangible example of the /Protozoa/ are the
/Foraminifera/. /Foraminifera/, like diatoms, have a shell-like
covering, and these shells, among the most plentiful of which are
those of the genus /Globigerina/, fall, as do those of diatoms, in
immense numbers to the bottom of the ocean, and form respectively
what are known as /Globigerina/ and diatomaceous ooze. In course of
time the sedimentary strata become fossilized; thus, the stone of
which the city of Paris is built consists of fossilized [pg022]
foraminifers, and the pyramids of Egypt are built of nummulites,
another genus of /Foraminifera/. It is estimated that an ounce of
this deposit contains four millions of these protozoans, so it is
impossible to conceive the numbers of once living animals represented
in the tombs of the Pharaohs. Telegraph-cables raised from the depth
of two miles bring the message to naturalists that the bottom of the
ocean at that depth is composed of little else than the calcareous
shells of /Foraminifera/.
Many of the lower animals resemble plants in form. Hydroids and
polyzoans are often gathered and preserved as seaweeds. Corals,
sea-anemones, and holothurians are curiously like plants. For a time
the confusion about the division of animals and plants was partly
owing to this resemblance of forms, and the theory of the animal
nature of corals was for a long time considered to be refuted by
the testimony of a naturalist who declared that he had seen them
in bloom. Later this class of animals was believed to occupy an
intermediate sphere and partake of the characteristics of both
kingdoms. The name zoöphyte, meaning "animal-plant" or "mingled
life," was adopted because of these resemblances and was formerly
applied to these forms only. To-day it has a broader application.
There is still a neutral class, called /Protista/, comprising
organisms which have not yet been classified as plants or animals.
[pg023]
V
DISTRIBUTION OF ANIMAL LIFE IN THE SEA
All living things which inhabit the sea have their appointed
boundaries, and the localization of marine life is as distinct as
is that of terrestrial life. Each kind of beach has forms of life
peculiar to itself. Those animals which inhabit rocky shores or stony
beaches or sand or mud may be looked for anywhere under similar
physical surroundings. They are, however, modified by climatic
conditions, and in wide ranges differ in genera and species. The
rocky coast of Maine has a class of sea-urchins and starfishes
which are different from those which live on the rocky shores of
the northern Pacific coast, yet they are all easily recognized as
belonging to the same family, and a description of typical forms is a
sufficient guide to the recognition of their relationships.
A bathymetrical division defines the classes of animals according
to the depth of water in which they live. Those which live near the
shore are /littoral/ species, those of the broad sea are /pelagic/,
while those living at great depths are /abyssal/.
Their modes of life are distinguished by other terms. Those which
float at or near the surface and are carried about by the currents,
like the jellyfishes and the minute organisms mentioned elsewhere,
are /plankton/. Strong swimming animals which move about at will are
/nekton/. Those which are fixed, like oysters, sponges, etc., and
those which crawl on the bottom, like crabs, echinoderms, etc., are
/benthos/.
Again, geographical divisions are named, in recognition of climatic
influences. The /boreal/ fauna and flora on the Atlantic [pg024]
coast extend from Cape Cod northward; the /American/, from Cape Cod
to Cape Hatteras; the /West Indian/, from Cape Hatteras southward. On
the Pacific coast the divisions, without definite names, are from the
Isthmus to Acapulco, Acapulco to the Gulf of California, Cape Lucas
to the Strait of Fuca. These divisions merge at indefinite lines,
but the above limits are generally accepted as the points of broad
division.
The shore or littoral fauna is especially abundant and comprises
more species that are curious in form and beautiful in color than
the others. The invertebrates of the deep sea are mostly transparent
and of a blue or violet tint, while the fishes are gray or bluish
above and white beneath, which renders them inconspicuous to their
enemies. [pg025]
VI
SOME BOTANICAL FACTS ABOUT ALGÆ
The vegetable world is separated into two great divisions:
/thallophytes/, or plants having no distinction of leaf or stem,
and /cormophytes/, or plants which have leaves and stems. All
thallophytes that live in the water and are nourished wholly by water
are called /algæ/.
A second great division of plants is into /cryptogams/, or those that
have no flowers, and /phanerogams/, or those that have flowers, by
means of which seeds are produced and successive generations of plant
life continued.
/Thallophytes/ and /cryptogams/ comprise the lowest and simplest
vegetable organisms. Algæ belong to both these divisions; to the
first because they have neither stems nor leaves, and to the second
because they have no flowers.
The lowest forms of algæ are microscopic in size, each individual
being a single cell; but in the ascending scale they attain curious
and beautiful shapes, some growing to a gigantic size and in forms
that resemble shrubs and trees. The green surface commonly seen on
the shady side of trees, on stone steps, and in other damp places is
one of the species of algæ which consist of a single cell. This plant
or cell divides, and the separate divisions divide and subdivide
again and again, and in time the aggregate number is great enough to
spread over a comparatively large surface, and thus become visible
to the naked eye. This plant, the /Pleurococcus vulgaris/, is a
fresh-water alga. The /Protococcus nivalis/, or red snow, described
on page 33, is a closely allied species. The green and blue-green
scums and slimes on [pg026] brackish ditches and on the stones and
woodwork of wharves are also species of the lowest orders of algæ
and increase by cell-division. Many of them are in colonies incased
in gelatinous matter. These, together with plants of a little higher
order, though still of low organization, the /Confervaceæ/, form a
large part of the green vegetation between tide-marks.
The vegetative body of a thallophyte is a /thallus/, and corresponds
to stem and leaf. It is also called a /frond/. What corresponds to
the root of flowering plants is in algæ a disk or conical expansion
of the base of the plant. It is simply a holdfast by which the frond
attaches itself to any submerged material. The algæ which grow on
sandy shores and on corals have holdfasts which branch like fibrous
roots and penetrate porous substances in all directions; but this
is only for greater stability, and is an adaptation to the habitat.
Holdfasts do nothing for algæ other than the name implies, whereas
real roots absorb the nourishment upon which plants live. Algæ are
nourished by the substances held in solution by the water which
surrounds them.
Algæ are the lowest and simplest in organization of all plants,
because they are composed of but one class of cells, such as in
flowering plants are called the /parenchyma/, or soft cells, these
being the ones which compose the pulp of the leaf. In the lowest
orders of algæ single cells constitute individual plants, as in
/Pleurococcus/; but in the higher forms, such as /Sargassum/, they
arrange themselves in such a variety of combinations as to resemble
plants which have leaf and stem. The botanical distinction is that in
leaf and stem there would exist the woody and the vascular cells as
well as the parenchyma cells.
Beginning with plants composed of a single cell, the next development
is into filamentous plants, which are single thread-like rows of
cells, as in /Cladophora/. In /Ulva/ is seen the earliest type of an
expanded leaf. The cells are here arranged in a horizontal surface of
plate-like or ribbon-like shape.
In /Ulva/ there is a double layer of cells. The layers separate in
/Enteromorpha/, giving a hollow or tubular form. In /Monostroma/ a
double layer is opened or torn apart, giving a frond with a single
layer of cells. [pg027]
The stem-like forms of certain algæ are composed of cylindrical
cells which combine or grow in a longitudinal direction chiefly.
Sometimes the cells are arranged evenly, in which case the stem
seems articulated, as in some species of /Ceramium/. Again, they are
irregularly placed, so that the stem appears solid.
The highest types of algæ in the differentiation of parts, or
vegetative forms, are to be found in the /Fucaceæ/, of the brown
seaweeds; the highest in the reproductive development, in the red
class.
Reproduction by cell-division, in which the organism itself breaks up
into two or more individuals, is called /vegetative reproduction/.
Higher forms reproduce by spores, or germ-cells, which give rise to
new individuals on germination.
The substance of an alga is more or less firm, according as the
vegetable mucus or gelatinous matter it contains has more or
less consistency; it is /membranaceous/ when the gelatine is
scant and glossy, /gelatinous/ when it is abundant and fluid, and
/cartilaginous/ when it is hard.
Some algæ are annuals; a few are perennials, and cast off and renew
their laminæ every season. Many plants present quite a different
appearance at different seasons of the year, and so are often
difficult to identify. Those which form spores throw off these
isolated cells, which sink or are washed to positions where they
germinate and begin their cycle of life. Many of the spores begin
their growth at once, without regard to season, so the species is
ever present. [pg028]
VII
NAMING OF PLANTS
The real or technical names of plants, which at first appear long and
unpronounceable, are in reality simple when the system of naming is
understood. Every plant has a /generic/ and a /specific/ name. The
generic name is analogous to the surname of a person, such as /Smith/
or /Jones/. The specific name is analogous to the Christian name of
a person, such as /John/ or /James/. The specific name never stands
alone, and would have as little designating character as John —— or
James ——.
This is called the /binomial/ (two-name) /nomenclature/. It was
introduced by Linnæus, and greatly simplified the system of naming.
The rule in scientific nomenclature is that all names must be Latin
or Latinized. This gives a universal language by which scientists of
all countries understand one another.
The names of classes (the highest groups) and subclasses are
adjectives or adjective nouns, expressing the most prominent
characteristic of the class or subclass. Thus the four subclasses of
the class /Algæ/ are:
/Cyanophyceæ/ (subclass of blue-green algæ).
/Chlorophyceæ/ (subclass of grass-green algæ).
/Phæophyceæ/ (subclass of dusky-brown or olive-green algæ).
/Rhodophyceæ/ or /Florideæ/ (subclass of red algæ).
Orders are, with few exceptions, the names of genera with the
termination /-aceæ/, as:
/Ulvaceæ/, from the genus /Ulva/.
/Ectocarpaceæ/, from the genus /Ectocarpus/.
/Gigartinaceæ/, from the genus /Gigartina/. [pg029]
Suborders, or groups between orders and genera, terminate in /-eæ/.
Names of genera are nouns or words taken as nouns. They are derived
from any source,—from prominent or peculiar characteristics, from
localities, or from names of botanists,—or they may be wholly
arbitrary. Personal generic names are divested of titles and take
a final /a/, or, in many cases, for euphony, /ia/. Thus, /Ulva/ is
the Latin for "sedge"; /Ectocarpus/ is from two Greek words meaning
"fruit outside"; /Corallina/ means "coral-like"; /Grinnellia/ is
named for Mr. Henry Grinnell.
The specific names are commonly adjectives, but sometimes they are
nouns, and occasionally are the names of the botanists who first
described the plants, in which case the name terminates in /-i/ or
/-ii/. The specific name always follows the generic name, thus:
/Ectocarpus Hooperi/, a species of /Ectocarpus/, first described by
Mr. Hooper.
/Grinnellia Americana/, a species, peculiar to America, of a genus
named for Mr. Grinnell.
/Griffithsia corallina/, a species resembling coral, and belonging to
a genus named for Mrs. Griffiths.
With regard to the four subclasses mentioned above, it should be said
that algæ are strictly classified in accordance with their methods
of reproduction; but since allied species have, with few exceptions,
the same color, the classification by colors is generally adopted as
convenient and sufficiently precise.
Familiar, or, in technical language, "vulgar," names are very
generally given to land plants, and especially to flowers; but
seaweeds are less in sight than flowers are, and so, save in a
few instances, have not been named except by the man of science.
To remember the scientific names will not be found difficult, for
without effort or special pains to acquire the new vocabulary, the
names, like those of new personal friends, will insensibly become
fixed in the memory.
In the body of this work each of the groups (class, subclass, order,
etc.), in the classification of both animals and plants, is indicated
by a special kind of type. [pg030]
VIII
DISTRIBUTION OF ALGÆ
The eastern coast of North America has been divided into four
sections, which correspond to the distribution of the algæ which are
characteristic of each section. The boundary-lines are not precise,
since some species of each section extend beyond the defined limits;
but arctic forms are not generally found south of Cape Cod, nor
can tropical varieties be expected north of Cape Hatteras. On the
intervening coast, however, there are some species common to both
sections. The divisions are: (1) Greenland to Cape Cod; (2) Cape Cod
to Cape Hatteras; (3) Cape Hatteras to Cape Florida; (4) the Florida
Keys and the shores of the Gulf of Mexico.
On the Pacific coast such distinct lines of demarcation do not exist,
there being no such natural barriers as are formed on the eastern
coast, first by Cape Cod, and, second, by the stretch of sand-beach
which extends from New York to Charleston, and which divides sharply
the climatic varieties.
The whole shore is again divided laterally into three distinct belts,
called the /littoral/, the /laminarian/, and the /coralline/ zones.
The first or littoral zone covers the space between tide-marks.
Vegetable life in this zone is subjected first to exposure to the
sun and air, and even to desiccation, and then to entire submergence
at constantly recurring periods. The rockweeds (/Fucus/), which
are so plentiful in this zone, are very gelatinous, nature having
apparently provided the gelatine to protect the cells of the plant
from the effects of the alternating extreme conditions. /Fucus/ and
/Enteromorpha/ predominate in this zone. [pg031]
The laminarian zone extends from low-water mark to the depth of
fifteen fathoms. The /Laminariaceæ/ and the beautiful red algæ
(/Florideæ/) grow here.
The third or coralline zone extends to the depth of about fifty
fathoms. The algæ of this zone, the nullipores, are incrusted with
a deposit of lime which gives them the appearance of corals; and,
singularly enough, the corals, which are animal forms, simulate plant
life.
Again, algæ have special habits and demand certain climates and
seasons for their growth. Algologists register the place where a
specimen is found, and in this way localities have been pretty well
determined. However, great exactness has not been reached, and the
collector is ever watchful to find an alga in some undiscovered home
within the given range. Although algæ grow from extreme high-water
mark to the depth of fifty fathoms, almost every variety may be
found on the beach, those growing in deep water being frequently
torn off and washed ashore by the waves. The heaps of sea-wrack
will often reward one who examines them carefully for deep-water
species. Seaweeds are most abundant on rocky shores, particularly
where there are stratified rocks with crevices, which afford shelter
from the waves. Rock pools often contain beautiful varieties of the
more delicate species. Red algæ will sometimes be found on the shady
side of these pools. Sand-beaches are unfavorable to the growth of
seaweeds, but fronds which have been carried long distances by the
currents will frequently be found on such shores. [pg032]
IX
SOME PECULIAR AND INTERESTING VARIETIES OF ALGÆ
The species of seaweeds that are known and classified are said to
number several thousands. These plants, which have neither vessels
for the conduction of fluids, nor fibers, consisting simply of
the first vegetable element, the cell, have, notwithstanding this
limitation, assumed a great variety of forms. In size they vary
from one one-thousandth of an inch in diameter, the smallest green
plants known, to those which exceed in length the height of the
tallest trees and form dense submarine forests, which in places make
comparatively deep water impassable for boats. In texture they vary
from a jelly- to a paper- and a leather-like consistency. In color
they have all the shades of green, brown, and red.
DIATOMS AND OTHER MINUTE ALGÆ
Among the smallest algæ are diatoms. They are microscopic in size,
but exist everywhere in both salt and fresh water, and are infinite
in variety as well as in numbers. They have a silicious, shell-like
covering, which divides and subdivides in their reproductive growth,
forming varied shapes which are exceedingly beautiful and interesting
to examine under the microscope. In vast numbers they float on the
surface of the sea, and, together with other minute free-floating
organisms, form the basis of food-supply for fishes. Their
indestructible shells fall to the bottom of the sea, forming large
deposits, which in time become fossilized. The city of Richmond,
Virginia, is built upon [pg033] a fossiliferous bed of diatoms,
which measures twenty to eighty feet in depth and several miles in
length.
Associated with diatoms, in fresh water, are desmids, which are green
in color and resemble the diatoms except in having a cartilaginous
instead of a silicious covering. Another minute organism, /Pyrocystis
noctiluca/, is luminous and is said to produce the beautiful
phosphorescent effects seen in tropical seas. /Trichodesmium/ is a
little alga which periodically occurs in great numbers, giving the
water a red appearance, as in the Red Sea, which is said to derive
its name from this circumstance.
RED SNOW
In the high latitudes of the arctic regions, also on snowy mountains
at altitudes where all vegetable life is supposed to be extinguished,
there sometimes appears a redness on the surface of the snow, which
in some cases extends for many miles. At a certain place in Greenland
the color was so vivid that an arctic voyager named the locality the
Crimson Bluffs.
The strangeness and almost sudden appearance of this color in the
snow have been so unaccountable to uninformed observers that it has
been ascribed by them to the falling of bloody snow and has been
regarded with superstition. The redness is caused by the growth of
one of the smallest of plants, the /Protococcus nivalis/. It is a
simple one-celled alga containing protoplasm and endochrome (red
coloring-matter). It grows by cell-division, the cell dividing into
four, eight, or sixteen parts on a quaternary scale. Each part
acquires a new covering while within the mother cell, and when it
emerges it is a complete individual and ready to repeat the process.
Only a few hours are required for its growth and development; hence
its increase is rapid, and it requires but a little time to make
itself manifest in those places where the conditions are favorable to
its existence.
THE SARGASSO SEA
When the voyager reaches a certain region of the North Atlantic,
called the Sargasso Sea, he sails into a vast undulating marine
[pg034] prairie. Farther than the eye can reach is spread a
yellowish-brown vegetation which covers the water as grass covers the
plain. Sometimes these weeds are so thick as to impede navigation,
and, seen from a little distance, seem substantial enough to walk
upon. At other times, according to seasons and conditions of storm
and wind, they are divided into strips or into island-like masses,
with spaces of clear water between. If the sailor did not know the
special conditions existing here he might suppose he had come upon
dangerous shallows; or were the waters less turbulent he might dream
that he was floating among the water-weeds of an inland lake.
This vast acreage of vegetation, as large as the continent of Europe,
lying southwest of the Azores and extending between the Canary and
the Cape Verde Islands, was first reported by Columbus, and takes its
name from the floating plant of which it is composed, the /Sargassum
bacciferum/, a species of the order /Fucaceæ/, commonly known as
gulfweed. Columbus's sailors took fright at the marvelous appearance
and wished to turn back, thinking they had reached the end of the
navigable ocean. They thought, if land were beyond, it was guarded
by shoals, and that the weeds concealed dangerous rocks. Columbus
threw out two hundred fathoms of line, but did not reach bottom,
and continued on his course for fifteen days before emerging into
clear water. From that day to this the Sargasso Sea has attracted
the attention of all navigators. It is especially interesting to
scientists. The physicist finds there the phenomenon of the ocean
currents holding in a vortex this immense mass of seaweed, the
zoölogist finds a great pasture in whose protecting shelter are
living and breeding countless numbers of marine animals, and the
botanist is puzzled because the source of this species of plant is
clouded with doubt.
[Illustration: PLATE II. Macrocystis pyrifera. Agarum Turneri.
Nereocystis Lütkeana.]
According to one theory, the plants are dislodged by the tempests
from terrestrial beds and carried by the Gulf Stream into the
huge eddy; but since there does not exist enough of the attached
plants of this species to supply the vast accumulation, another and
more generally accepted theory is that the gulfweed lives also a
pelagic life and adapts itself to the conditions of the [pg035]
floating state, thus dispensing with the disk-like root, as it
needs no holdfasts, and propagating solely by lateral and axillary
ramification.
There are said to be one hundred and fifty species of /Sargassum/,
but /S. bacciferum/ alone constitutes the beds of the Sargasso Sea.
The plant is the most highly differentiated of any seaweed, in that
it more nearly approaches the true leaf and stem, and is described
botanically as follows: Frond furnished with distinct, stalked,
nerveless leaves and simple, axillary, stalked air-vessels. The
integument is leathery, and the color brown of varying shades. The
most striking peculiarity is the abundance of globular cells. These
berry-like air-bladders give the plant buoyancy enough to support the
weight of its innumerable guests. (Plate XVI.)
THE LAMINARIACEÆ
In the laminarian zone, described above, grow the /Laminariaceæ/, an
order of brown seaweeds, some of whose genera grow to enormous size,
and in some places form dense submarine forests. Darwin speaks of the
good service rendered by these plants to vessels navigating stormy
coasts, where often they act as natural breakwaters, and again as
buoys designating dangerous rocks near the shore on which they grow.
The seaweeds belonging to this order, commonly known as oarweeds,
tangle, devil's-apron, and sea-colander, are frequently seen twelve
to twenty feet in length, and others are measured by fathoms. One
of the giant plants is /Nereocystis Lütkeana/, which occurs on
the northwest coast. It has a stalk, sometimes three hundred feet
in length, which bears on its extremity a barrel- or cask-shaped
air-vessel, six or seven feet long, from the surface of which a tuft
of fifty or more forked laminæ grows to a length of thirty or forty
feet. The stem which anchors this immense frond is so small that the
Aleutian Indians use it for fishing-lines. The sea-otter makes his
home on its huge air-vessel, and the plant is called by the Russians
the "sea-otters' cabbage."
But the longest of all known plants is the alga /Macrocystis/. Its
thin naked stem, the diameter of which seldom exceeds one quarter
[pg036] of an inch, is reported by one author to be seven hundred
feet in length, by another fifteen hundred feet. It is terminated
by a lamina fifty feet long, resembling a pinnatifid leaf, each
leaflet of which, at its point of division on the stem, expands into
an air-vessel as large as an egg. These air-vessels sustain the
immense frond which floats on the surface of the water, its leaflets
depending in a vertical position from the stem. /M. pyrifera/, the
only species, is found in the Southern oceans and on the Pacific
coast of North America.
/Lessonia/, another genus, resembles a palm-tree. It grows erect to
a great height and has a stem like the bole of a tree. It branches
in a forking manner and has depending from its branches laminæ two
or three feet long. The large stems from which the laminæ have been
torn by the storms, and which have been cast ashore on the Falkland
Islands, as described by Sir Joseph Hooker, resemble driftwood, as
they lie in piles three or four feet high and extending for many
miles.
/Agarum/ and /Thalassiophyllum/ are arctic genera, but they are found
within our limits, the former in the North Atlantic. It has a simple
but enormous leaf-like frond. The latter, which is found on the North
Pacific coast, has a compound frond. Both are characterized by their
fronds being perforated throughout with holes, giving them the name
of sea-colander. [pg037]
X
USES OF ALGÆ
Water covers two thirds of the surface of the earth, and algæ, with
a very few exceptions, constitute the whole vegetation which exists
in that enormous area. They have, therefore, an important part to
perform in the economy of nature. Algæ do not, like land plants,
derive their nourishment from the soil to which they are attached,
but from substances held in solution by water. In their growth they
effect changes in the water analogous to those effected by land
plants in the air; that is, they change so-called impurities in the
water into materials essential to animal life. The function of plants
is that of transforming or manufacturing inorganic matter, which they
assimilate, into organic matter (such as starch, albumen, sugar),
which forms their own structure and which is the food essential to
animals. In this process, plants inhale carbonic acid gas which
animals breathe out, and exhale oxygen which animals breathe in.
Plants feed on mineral substances and furnish vegetable food, thus
keeping up the balance of life.
Fresh-water algæ have a like economic value. The green surface on
stagnant pools is a vegetable growth whose function is to assimilate
the matter which makes the pool offensive. A submerged district soon
becomes covered with scum, or minute plants (/Sphæoplea annulina/),
which grow with great rapidity, using up the materials of the
decaying vegetation, and in great measure counteracting the ill
effects, in the atmosphere, of such decay. When the waters subside,
the plants shrivel up and appear like thin paper covering the ground.
This ephemeral substance soon [pg038] disappears, without giving
evidence of its nature in dust or gases, its body seeming to be a
machine which transmutes, but does not hold, the substances on which
it grows.
Algæ, as has been said above, grow in definite zones, and each
zone has also a definite animal life which finds there its food.
Darwin says: "In all parts of the world a rocky and partially
protected shore perhaps supports in a given space a greater number
of individual animals than any other station." And speaking of the
/Laminariaceæ/, he adds: "I can only compare these great aquatic
forests of the southern hemisphere with the terrestrial ones in the
intertropical regions. Yet if in any country a forest was destroyed
I do not believe nearly so many species of animals would perish as
would here from the destruction of the kelp." The same may be said of
the Sargasso Sea, where millions of living creatures make their home.
In every kind of marine fauna there are species which derive, if not
the whole, at least a part of their nourishment from the seaweeds.
The vegetation in the narrow boundary of the three zones is
palpably inadequate to supply the needs of the animal life which
exists in deeper waters. But over the broad area of the ocean
there exists a vast number of pelagic, free-floating algæ, which,
although microscopical in size, are almost infinite in numbers.
In illustration of this it has been estimated that, although they
are not especially numerous in the Sargasso Sea, yet if all the
seaweed there were gathered into one mass and the free-floating
algæ into another, the bulk of the latter would exceed that of the
former. The pelagic flora consists of /Diatomaceæ/, /Protococcaceæ/,
/Peridinieæ/, and others. Undoubtedly it is on these pastures that
fishes feed, as well as other organisms which in turn are food for
fishes.
/Fucus/ and /Laminaria/ constitute the kelp from which iodine is
obtained, and were at one time the source of the potash of commerce.
/Fucus vesiculosus/ is a constituent of a medicine used as a cure for
obesity. /Chondrus crispus/, commonly known as Irish moss, was a few
years ago generally used as an article of diet. /Porphyra vulgaris/
(laver) is used by the Chinese for soups. /Rhodymenia palmata/
(dulse) is an article of food in Ireland and Scotland. [pg039]
/Gracilaria spinosa/ is used by birds, allied to the swallows, for
making their nests—the edible nests found in large numbers on the
islands of the Indian Archipelago, especially in the caves on the
shores of Java, and gathered and sent to China, where they bring
large prices and are used in making the famous birds'-nest soup.
/Gracilaria lichenoides/, also a species of the Eastern seas, is
the source of agar-agar, a preparation used in laboratories as a
culture-medium for bacteria. Fossil diatoms are ground and used for
polishing-powders. Seaweeds are everywhere used by farmers on the
coasts as fertilizers. [pg040]
XI
COLLECTING AT BAR HARBOR
The beautiful coast of Maine is a particularly good field for
shore-collecting. The rocky coast harbors the boreal fauna and flora
which depend upon such physical conditions, and the shores at Bar
Harbor are typical of those found elsewhere in northern New England.
The rocks give shelter from the beating surf, while life has exposure
to the cold, pure waters of the arctic current. Everywhere along
the shore, rock pools are to be found. These are perhaps the most
fascinating of all spots to the collector. They are veritable gardens
of the sea, where species flourish which naturally belong to deeper
water, but which find in such pools conditions suitable to their
existence.
At Bar Harbor one well-known and frequently visited rock pool is
found in Anemone Cave. Entering a field at Schooner Head, one
turns to the right and follows the rocky shore for two or three
hundred feet. It is difficult to take this short walk without being
constantly diverted and delayed by the various attractions one meets,
such as the tide-pools, the barnacles which in places whiten the
rocks, the periwinkles, the purpura shells, and the curious algæ; but
at last one arrives at a cavern under an overhanging rock. Here is a
large tide-pool which at first sight displays only a beautiful scheme
of color. It is carpeted with a bright-pink alga, /Hildenbrandtia
rosea/, which incrusts the basin of the pool.
Interspersed with the pink are patches of a deep-red color, having
a velvety appearance, which are formed by another crustaceous alga,
/Petrocelis cruenta/. The water of the pool is of crystal [pg041]
clearness, and as one gazes into it one object after another comes
into view, until one is filled with astonishment at the number of
beautiful objects the pool contains. The little green balls, one
half of an inch to one inch in diameter, which look like small green
tomatoes scattered on the stones, are /Leathesia difformis/, an
alga which cannot be mistaken for any other. Bunches of /Corallina
officinalis/, which resembles coral, as the name indicates, are
abundant. This alga should be examined with a magnifying-glass. It is
covered with calcareous matter, and its peculiar form of growth is
beautiful and interesting.
The fronds of the laminarian /Alaria esculenta/ are tiny here,
while just outside the cave they are to be seen several feet in
length, beating against the rocks in the swash of the waves. Thorny
sea-urchins (/Strongylocentrotus drobachiensis/) make green spots
which look like tufts of moss. Yellow and green sponges in little
cones are spread over small surfaces. Starfishes and ophiurans
are plentiful. The /Purpura lapillus/ and /Littorina litorea/ and
/rudis/ (periwinkles), so plentiful on this coast, are present. The
/Mytillus/ and the /Saxicava/ and the /Acmæa testudinalis/ are also
to be found. A green crab (/Carcinus mænas/) is snugly hidden in a
dark nook on the shady side of the pool, and many small crustaceans
scuttle away from under stones as they are lifted. The collector
is always anxious for uncommon, or rather less plentiful, species,
and here are found two specimens of nudibranchs, or naked mollusks,
/Æolis/ and /Dendronotus/. The /Chiton ruber/, a jointed mollusk, was
also found here, and five species of sea-anemones were counted. As
this is a favorite hunting-ground, the anemones have not been left
to attain full growth; but there are very many small ones which at
first are not distinguishable, as they retract their tentacles at the
slightest disturbance of the water and are then quite inconspicuous.
After a little time of quiet watching they will be seen putting out
their tentacles and expanding their beautiful flower-like forms.
It is useless to try to capture them uninjured, so tightly do they
adhere to the rocks, and the difficulty of preserving them in an
expanded form is so great that amateur collectors had better leave
them undisturbed to beautify the pool. [pg042]
It was hard to resist robbing this rock pool, where the author in
half an hour counted twenty different species, and finally left,
feeling that its treasures were not half discovered; but collecting
should be done elsewhere, and this pool be guarded as a gem to be
admired and not to be despoiled.
This pool in Anemone Cave, although so very attractive, is surpassed
in beauty and interest by pools on Porcupine Island, at the base
of the cliff. This place is somewhat difficult of access, and the
timid will not undertake the descent to it; but the enthusiastic
collector, who overlooks small obstacles, will be repaid by a visit
to this spot, where all the treasures of Anemone Cave are multiplied
many times over. These pools are resplendent with large anemones,
hydroids, nudibranchs, mollusks, echinoderms, crustaceans, and
algæ. /Alaria esculenta/, several feet in length, is beaten to a
fringe against the rocks, and /Agarum Turneri/, the sea-colander, is
also found here, together with beautiful specimens of /Rhodymenia
palmata/, which is so plentiful that it reddens the rocks.
A /Metridium marginatum/, the most common sea-anemone of this coast,
was taken here which measured six inches in diameter. This creature
threw out so many of the processes used for defense that it seemed at
first as though it were covered with some seaweed; but the worm-like
movements of these threads, which measured six inches or more in
length, soon disclosed their nature.
On the more accessible shores of Porcupine Island are found the naked
mollusks (nudibranchs) /Æolis/ and /Dendronotus/. Clinging sideways
to the rocks just above high-water mark are many shells of /Littorina
rudis/. They are fastened to the rocks by a glutinous deposit along
the outer lip, and the peculiar exposure of the open end, as well
as the position above tide-mark, indicates that this animal is
undergoing transformation into a land species. /Littorina palliata/
is abundant on the rockweeds (/Fucus/); some of the specimens are
banded with yellow, and all closely simulate the seaweed on which
they cling. Beautifully banded specimens of /Littorina litorea/ are
also plentiful. Among other shells which are abundant here as well as
elsewhere on this coast are /Purpura lapillus/, /Acmæa testudinalis/,
/Buccinum undatum/, /Mya arenaria/, and /Mytillus edulis/. [pg043]
Under the rockweeds in small pools and crevices are the polyzoans
/Bugula turrita/ and /Membranipora pilosa/, and the hydroids
/Sertularia pumila/ and /S. argentea/.
The seaweeds /Rhodymenia palmata/ (dulse) and /Desmarestia/ are
plentiful; also beautiful worms, crustaceans, and starfishes.
A very interesting beach is found a few hundred feet south of Otter
Cliffs, to which an easy descent is made if one follows a pathway
leading to it through a grove adjacent to the drive. Here one will be
interested in the study of numerous and beautiful rock pools.
Sea-urchins (/Strongylocentrotus drobachiensis/) seem to carpet some
of them, having the appearance of mossy tufts. Beautiful pink and
purple starfishes (/Asterias vulgaris/), brittle-stars (/Ophiopholis
aculeata/), sea-cucumbers (/Pentacta frondosa/), sea-anemones, and
crabs are abundant. If one lifts a stone the little crustaceans
/Orchestia/ and /Gammarus/ will hurry away, and very likely an
interesting worm or a nudibranch will be found. It is also most
interesting to watch the barnacles, which are below the surface,
reaching out their curled, feather-like feet in regular rhythmic
grasping motions. The common mussels (/Mytillus edulis/), which in
places blacken the shore, are beautiful under examination, and the
silky network or byssus which forms the anchorage should be observed.
The rocks are hung so plentifully with /Ascophyllum nodosum/
(rockweed) that its beauty is likely to be passed over unnoticed.
On the /Ascophyllum/ is growing in tufts /Polysiphonia fastigiata/;
other seaweeds, /Rhodymenia palmata/, /Chordaria flagelliformis/,
/Desmarestia aculeata/, /Corallina officinalis/, and /Ceramium/, are
so abundant that one forgets to value them at the moment. Higher up
on the beach the rocks are spotted with papery sheets, which, floated
out in water, prove to be the beautiful purple /Porphyra/. A fine,
dark colored, hairy scum on the rocks is /Bangia fusco-purpurea/.
Sometimes one finds here fronds of /Laminaria/ which have been washed
ashore. Various green algæ are abundant. Even if not collecting, it
is well to carry a small tin pail to the beach and float out pieces
of the algæ in order to observe carefully, if but for a moment, the
beautiful forms they have in their natural state. Watched for a few
minutes in a pail of water animals disclose curious [pg044] and
surprising forms and habits which are difficult to watch leaning over
a pool.
Most of the various species mentioned above are common along the
whole shore, and may be looked for at almost any point where the
water is free from contamination.
At the sand-beach are found species which do not inhabit the rocky
shore, as the sand-dollar (/Echinarachnius parma/), /Polynices/
(/Lunatia/) /heros/, /Mya arenaria/, and others. After a storm
various deep-water forms are washed upon this beach. /Laminaria
digitata/, six feet long, is found here sometimes under these
circumstances. /Chordaria flagelliformis/, resembling long switches
of hair, floats from the rocks near the shore. To the left, on the
rock under the overhanging ledge, is a tide-pool which one would
hesitate to deface by touching a single specimen. So crystal-clear
is the water, so brilliant the /Hildenbrandtia/, so lovely the
/Corallina/, that all seem placed there to excite admiration.
But most of all one should obtain the permission of the owner to
visit Rodicks Weir. Here is an immense natural aquarium, full of
living wonders. On a clear day, sunlight penetrates to the bottom,
and at low tide the whole contents of the weir are clearly seen as
one floats through the inclosed water-spaces. On the bottom are
sea-urchins, many of them with sticks or stones on their backs, which
the animals have placed there in the endeavor to conceal themselves;
starfishes feeding; and great numbers of whelks (/Buccinum undatum/).
Cuttlefishes dart rapidly about, and skates, sculpins, and other
fishes display their curious forms. Very likely a giant jellyfish
(/Cyanea arctica/) is entangled in the brush, so that one can examine
at short range its wonderful and beautiful parts. Other jellyfishes
may be closely scrutinized.
The alga /Polysiphonia violacea/ floats in long feathery tufts from
the stakes.
On the eel-grass are to be found /Lacuna vincta/ and the delicate
iridescent little shells of /Margarita helicina/.
Every tide brings different species of the ocean fauna to temporary
imprisonment in this inclosure, so that it is difficult to say what
one may not chance to find in this interesting place.
PART I
MARINE ALGÆ
SEAWEED
When descends on the Atlantic
The gigantic
Storm-wind of the equinox,
Landward in his wrath he scourges
The toiling surges,
Laden with seaweed from the rocks;
From Bermuda's reefs; from edges
Of sunken ledges
In some far-off, bright Azore;
From Bahama and the dashing,
Silver-flashing
Surges of San Salvador;
* * * * *
Ever drifting, drifting, drifting
On the shifting
Currents of the restless main;
Till in sheltered coves, and reaches
Of sandy beaches,
All have found repose again.
LONGFELLOW.
I
BLUE-GREEN SEAWEEDS (CYANOPHYCEÆ)
GRASS-GREEN SEAWEEDS (CHLOROPHYCEÆ)
TABLE SHOWING THE CLASSIFICATION OF THE BLUE-GREEN SEAWEEDS DESCRIBED
IN THIS CHAPTER
Class =ALGÆ=
Subclass =Cyanophyceæ= (/Blue-Green Seaweeds/)
Order =NOSTOCACEÆ=
Genera Species
^Spirulina^
^Oscillaria^
^Calothrix^
^Lyngbya^ ^L. majuscula^
^L. ferruginea^
[pg049]
BLUE-GREEN SEAWEEDS
The minute algæ, which form patches of purple color on rocks, slimy
layers or spots on wharves, bluish-green slime on mud, emerald-green
films on decaying algæ, blue-green slime on brackish ditches, and so
on, are various species of the subclass =Cyanophyceæ=. The prevailing
color of these plants is blue-green, but some are purple, brown, or
pink. Some of them are gelatinous in texture and shapeless, others
have more definite forms; but all are too small to classify without
the aid of a powerful glass, and are not of special interest except
to the botanist.
GENERA ^Oscillaria^ and ^Spirulina^
The genus ^Oscillaria^ is so named from an oscillating movement which
these filamentous plants show when viewed under the microscope. They
are very delicate blue-green threads occurring singly, or in loose or
felt-like floating masses, or like slime or scum, on mud or woodwork.
In ^Spirulina^ the filaments are spirally twisted like a corkscrew
and also have a vibrating movement. /Spirulina/ is often found
growing with /Oscillaria/, and forms purple patches on wharves.
GENUS ^Calothrix^
("/Beautiful hair/")
Filaments one tenth of an inch long, terminating in transparent
hair-like points, occasionally branching. The plant grows in fine
tufts or like a fringe on algæ or in patches on rocks. Sometimes it
forms a spongy layer, again a velvety stratum. The color varies in
different species; it may be bright green, brownish-green, [pg050]
or dark bluish-purple. The genus is very common, and the plants are
often found on the bottoms of boats.
GENUS ^Lyngbya^
(/Named for Hans Christian Lyngbye, a Danish botanist/)
^L. majuscula^, mermaid's-hair. The filaments are curled or
crisped, long, thick, and tenacious, matted together at the base,
and blackish-green. The species grows in tufts on eel-grass and
algæ, and is often found floating free. It is common in summer
everywhere south of Cape Cod and on the Pacific coast.
^L. ferruginea^ or ^æstuarii^. In this species the filaments are
thin, soft, and without stability (flaccid), so that they lie flat
like a thin stratum. They are verdigris-green in color, and are
found in brackish pools and ditches and on muddy shores near the
sea. [pg051]
TABLE SHOWING THE CLASSIFICATION OF THE GRASS-GREEN SEAWEEDS
DESCRIBED IN THIS CHAPTER
Class =ALGÆ=
Subclass =Chlorophyceæ= (/Grass-Green Seaweeds/)
Order Genus Species
=CONFERVACEÆ= ^Ulothrix^
^Chætomorpha^ ^C. melagonium^
^C. ærea^
^C. linum^
^Cladophora^ ^C. arcta^
^C. rupestris^
^C. gracilis^
=ULVACEÆ= ^Ulva^ ^U. lactuca^
^U. latissima^
^Enteromorpha^ ^E. clathrata^
^E. compressa^
^E. intestinalis^
^E. lanceolata^
^Monostroma^
Group =Siphoneæ=
=VALONIACEÆ= ^Chamædoris^ ^C. annulata^
^Anadyomene^ ^A. flabellata^
=DASYCLADACEÆ= ^Acetabularia^ ^A. crenulata^
^Dasycladus^ ^D. occidentalis^
^Cymopolia^ ^C. barbata^
=UDOTEACEÆ= ^Penicillus^ ^P. dumentosus^
^P. capitatus^
^P. Phœnix^
^Udotea^ ^U. flabellata^
^U. conglutinata^
^Halimeda^ ^H. tuna^
^H. tridens^
^H. opuntia^
=CODIACEÆ= ^Bryopsis^ ^B. plumosa^
^Codium^ ^C. tomentosum^
=CAULERPACEÆ= ^Caulerpa^ ^C. prolifera^
^C. Mexicana^
^C. plumosa^
^C. Wurdemanii^
[pg052]
GRASS-GREEN SEAWEEDS
"There can hardly be a more fascinating group of plants than this,
whether to the strictly scientific botanist or to the more catholic
lover of nature. The green algæ are among the most widely diffused
of plant forms. They grow practically in every place where enough
moisture, together with light and air, is to be had. Between
tide-marks on almost every coast, floating on the surface of the deep
sea, covering damp earth, walls, palings, and tree-trunks, sticking
to the surface of leaves in the moist atmosphere of tropical forests
and jungles, and inhabiting almost every river, brook, pond, ditch,
or casual pool of rain-water in all quarters of the globe, are
members of this ubiquitous group to be found."[3]
[Footnote 3: Kerner.]
The grass-green seaweeds are more simple in structure, and therefore
are lower in order, than the red or brown algæ. They are among the
lowest of all plants, many of them being minute single cells. They
abound in fresh as well as in salt water, and in this respect differ
from the other groups, the red and the brown algæ being almost
exclusively marine plants.
As one approaches the shore, the attention is often attracted by the
green mantle which covers everything overflowed by the tides. This
consists largely of the confervoid algæ, which are very abundant and
are found almost everywhere. They are dense tufts of fine thread-like
plants, often matted at the base; sometimes they are sponge-like,
floating masses.
The =Ulvaceæ=, the plants next higher in order, are the first which
assume ribbon- and leaf-like expansions, and usually first engage the
attention of the collector. [pg053]
In the green algæ are found the extreme forms of one-celled plants.
In ^Pleurococcus^ the cell is microscopic in size. In the =Siphoneæ=
the plant still consists of a single cell, but it attains large
dimensions and develops into forms resembling, in outward appearance,
leaf, stem, and root (see /Caulerpa/).
Other plants consist of single rows of cells, called filaments
(=Confervaceæ=), or of cells arranged in layers or flat surfaces,
called membranes (=Ulvaceæ=).
ORDER =CONFERVACEÆ=
The silkweeds. This order is characterized by cylindrical cells
strung end to end, forming threads or filaments, branched and
unbranched. The plants inhabit both fresh and salt water, and are
very abundant and widely distributed. They grow in dense tufts, often
matted at the base.
GENUS ^Ulothrix^
A yellow-green, unbranched, decumbent, soft, hair-like fleece on the
surface of rocks, extending indefinitely. This genus differs from
/Chætomorpha/ in the character of its filaments, which are soft and
gelatinous in ^Ulothrix^, but bristle-like and wiry in /Chætomorpha/.
GENUS ^Chætomorpha^
The frond is filiform; the filaments are coarse, rigid, and
unbranched. In some species the filaments grow straight and in
tufts from a definite base; in others they are twisted together
and are prostrate. Often they are found floating in masses. In ^C.
tortuosa^ the filaments are as fine as human hair, but rigid, and so
closely interwoven as to resemble a layer of wool on the rocks. The
cell-divisions give a striped appearance to the filaments when dry.
^C. melagonium.^ This species is dark green, with filaments erect,
coarse as a double bristle, and wiry; five to twelve inches long.
It is found in rock pools from Boston northward. It does not adhere
to paper in drying, and loses its color if immersed in fresh water.
(Plate III.)
^C. ærea.^ Yellowish-green, with filaments erect and less rigid
than [pg054] in /C. melagonium/, which it otherwise resembles;
tufts three to twelve inches long; cell-divisions very marked. This
species is found in rock pools from Cape Cod to New York Bay.
^C. linum.^ Bright green; filaments coarse, rigid, twisted
together, and prostrate. It is found floating in masses and forming
strata on rocks and gravel from New York northward. It is thought
by some that this, as well as ^C. picquotiana^, which it closely
resembles, is not a true species, but consists of the mature plants
of the species /C. melagonium/ and /C. ærea/, which have become
detached from their holdfasts and have continued to grow. (Plate
III.)
GENUS ^Cladophora^
("/Branch-bearing/")
Frond filiform, branched. There are many species of ^Cladophora^,
which differ from one another in their branching, color, and size.
They abound on rocks at low-water mark, in tide-pools, in muddy
ditches, and on wharves. They are especially characterized by being
so profusely branched as to form tufts or spherical masses, by which
the collector can easily distinguish the genus.
^C. arcta.^ Bright, glossy green; filaments fine, erect, much
branched, two to eight inches long; tufts dense, more or less
entangled, and in bunches, giving a starry effect. The species is
common on rocks near low-water mark from New York northward. The
plants vary slightly in appearance with the season. (Plate III.)
^C. rupestris.^ Dark green; filaments straight, rigid, tufted;
branches crowded; many branchlets flattened against the filaments,
so that the alga somewhat resembles grass; five to ten inches long.
The cell-divisions show plainly. Plants of this species do not
adhere to paper in drying. They are found on rocks at low-water
mark, and are common on the northern New England coast. (Plate III.)
^C. gracilis.^ Bright yellow-green; filaments very fine, loosely
tufted, three to twelve inches long, soft, silky, much branched;
branches rather short, and branchlets more or less curved and
arranged in a comb-like manner. It grows on wharves, in muddy
pools, and on eel-grass. (Plate IV.)
[Illustration: PLATE III. Chætomorpha melagonium. Chætomorpha linum.
Cladophora arcta. Cladophora rupestris.]
[Illustration: PLATE IV. Cladophora gracilis. Ulva lanceolata. Ulva
lactuca, var. rigida. Enteromorpha clathrata.]
ORDER =ULVACEÆ=
The plants of this order are, with few exceptions, formed of celled
surfaces and show the earliest type of an expanded leaf. The cells
form thin membranes, which sometimes are broad surfaces of no
definite shape, sometimes are narrow and ribbon-like, or they may be
simple or branched tubes. When the membrane [pg055] consists of
a single layer of cells it is ^Monostroma^ ("one layer"); when it
consists of a double layer it is ^Ulva^; when the layers separate,
the thallus becomes hollow, and it is then ^Enteromorpha^. These
plants are mostly a brilliant grass-green in color, are silky in
texture, and are attached by a small disk to rocks and stones. They
abound everywhere, and are commonly known as /green laver/.
GENUS ^Ulva^
Frond a thin, silky, flat membrane, sometimes leaf-like, again an
extended surface of no definite shape. These are the largest green
algæ. They are common everywhere.
^U. lactuca^, the sea-lettuce. Frond a flat membrane of various
shapes, sometimes orbicular, again deeply incised, often
ribbon-like; margin always much waved or ruffled. In the variety
^rigida^ the frond is oval in outline, not very large, and quite
firm or rigid. The species is found on rocks exposed to the action
of the waves. (Plate IV.)
^U. latissima.^ Frond a flat, expanded membrane of indefinite
shape, but general outline oval, never ribbon-like; attains a
size of twelve to twenty-four inches; often deeply lobed, very
waved, often perforated with holes; membrane brilliant green,
thin, smooth, glossy. It grows apart or in tufts, and is found
everywhere, in all stages of growth. It is the largest species of
/Ulva/, and is very common on muddy shores.
GENUS ^Enteromorpha^
Fronds tubular, simple or branched, sometimes inflated. The tubes
vary in size in different species and also in the same species, some
being fine like a hair, others large, and flat or inflated. The genus
is widely distributed and very abundant. Species of ^Enteromorpha^
grow on the bottoms of ships, and in nautical language are called
/grass/.
^E. clathrata.^ Fronds thread-like, tubular, branched, and branches
beset with numerous fine branchlets; densely tufted, soft. Common
everywhere. (Plate IV.)
^E. compressa.^ Fronds long, slender, branched, tufted; branches
simple, compressed, extending from main central branch, obtuse
at ends, but attenuated at base. The species is very abundant
everywhere, and is a useful plant for the aquarium. (Plate V.)
^E. intestinalis.^ Single, long, inflated tubes or sacs, obtuse at
the apex, very attenuated at the base; fronds often crimped and
twisted, resembling an intestine, whence the name. (Plate V.)
[pg056]
^E. lanceolata.^ Formerly called /Ulva Linza/. Frond narrow,
ribbon-like, six to twelve inches long, one inch to two inches
wide; blunt or pointed at apex, tapering at base; attached by a
disk; edges much ruffled; bright green, soft, thin.
GENUS ^Monostroma^
This genus resembles /Ulva/, but is more delicate since it
has but one layer of cells, as its name implies. The frond is
usually sac-like at first, then breaks apart, leaving a thin,
semi-transparent membrane of no definite shape.
GROUP =SIPHONEÆ=
The distinct and peculiar character of this group is that in each
individual the whole plant consists of but one cell. There are many
genera, some of which are plants of elaborate form and considerable
size, but always the one cell expands and branches without dividing
the elongated cavity with septa, or plates of division. In ^Caulerpa^
the stability of the plant is secured by numerous fibrils which
emanate from the interior of the cell, forming a spongy network of
interlacing filaments. In other orders the branches gain support from
incrustation, from interlacing, and from cohering on the edges.
ORDER =VALONIACEÆ=
The algæ of this order are found only in tropical or subtropical
waters. Their holdfasts resemble fibrous roots and penetrate the sand
or coral on which they grow.
GENUS ^Chamædoris^
^C. annulata.^ When young this alga consists of an annulated tube
formed of a single cell. The annular constrictions occur at short
intervals, giving it the appearance of being jointed. It grows to
the height of two to three inches, when it ceases to lengthen and
produces a dense mass of filaments, forming a head or spherical
tuft one inch or more in diameter. It is bright grass-green in
color, rather rigid and tough, and when mature is thinly coated
with carbonate of lime. The holdfast is a tuft of fibers. The
species is found at Key West and is a native of the West Indies.
[Illustration: PLATE V. Enteromorpha compressa. Enteromorpha
intestinalis. Enteromorpha intestinalis. Anadyomene flabellata.]
[Illustration: PLATE VI. Acetabularia crenulata. Dasycladus
occidentalis. Penicillus dumentosus. Udotea conglutinata.]
GENUS ^Anadyomene^
^A. flabellata.^ Frond composed entirely of branching filaments,
which unite and form an undulating, rigid membranaceous surface,
which seems like a network of veins. The species grows in bunches
on short stems in the fissures of tidal rocks, and at first view
resembles young /Ulva/. It is a very curious and beautiful alga,
and should be examined with a glass. It is one inch to four inches
in diameter when full-grown. (Plate V.)
ORDER =DASYCLADACEÆ=
This order also inhabits only tropical or subtropical seas. It is
placed in this group, although only the main axis is unicellular.
The one-celled axis is surmounted or encircled by whorls of minute
filaments or branchlets (/ramuli/), which protrude through small
holes and are either persistent or deciduous. In the latter case the
fallen filaments leave disk-like scars on the stem.
GENUS ^Acetabularia^
^A. crenulata.^ This little alga resembles a mushroom of the
/Agaricus/ variety or gilled species, and so is easily identified.
It is thinly incrusted with lime and is found on rocks and coral,
within tide-marks, on the Florida reefs. When full-grown the stipe
is two to three inches long and the cap one half of an inch in
diameter. (Plate VI.)
GENUS ^Dasycladus^
Fronds destitute of calcareous matter, soft, cylindrical or
club-shaped; single unicellular axis, beset with fine filaments or
ramuli.
^D. occidentalis.^ Frond club-shaped, one to two inches high, one
half of an inch or less in diameter; covered with whorls of fine
filaments, making the fronds almost spongy; substance soft but
tough; dark green. These plants have been compared to foxes' tails.
They grow in bunches on rocks between tide-marks. (Plate VI.)
GENUS ^Cymopolia^
^C. barbata.^ Frond branched, dividing regularly in pairs; thickly
incrusted with lime. Annular constrictions at short intervals give
the branches the appearance of strings of beads. Each section
is covered with pores or scars of fallen ramuli. The branches
terminate in tufts of fine filaments. [pg058]
ORDER =UDOTEACEÆ=
GENUS ^Penicillus^
The merman's shaving-brush, characteristic of coral reefs.
^P. dumentosus.^ Holdfast much branched, like a fibrous root, and
penetrating deep into the coral or sand; stem short, thick, more
or less flattened, sometimes hollow, covered with velvety scurf;
top covered with loosely spreading tuft of soft filaments three to
six inches long, which branch repeatedly in pairs (dichotomous);
color deep green. When old, these plants are incrusted with a thin,
porous layer of carbonate of lime. (Plate VI.)
^P. capitatus.^ Holdfast a dense mass of fibers two or more inches
long; stipe one to five inches long, one fourth to one third of an
inch in diameter, usually cylindrical, sometimes wider at top than
at base, sometimes flattened; thickly incrusted with lime, which is
smooth and often polished; top a dense, spherical mass of filaments
one to two inches in diameter; filaments branching dichotomously,
and rigid from incrustation of lime.
^P. Phœnix.^ Stipe cylindrical, one to three inches long,
one fourth of an inch in diameter, thickly incrusted with lime,
smooth; capitulum or head ovoid, and composed of filaments which
are incrusted with lime and coherent, forming many distinct, flat,
wedge-shaped, level-topped, spreading laminæ. This species is found
at Key West.
GENUS ^Udotea^
^U. flabellata.^ Short, flattened stem, expanding into a broad,
fan-shaped, smooth frond, concentrically zoned; margin wavy;
thickly incrusted with lime. Abundant at Key West.
^U. conglutinata.^ Deeply descending root; stem expanding into
fan-shaped frond; entire, lobed, or irregularly torn; slightly
incrusted with lime. The frond is composed of longitudinally
parallel, adherent filaments, which are visible, giving a striated,
rough surface. (Plate VI.)
GENUS ^Halimeda^
This genus resembles the corallines externally, and is abundant on
coral reefs. It appears as if formed of separate parts, resembling
a series of heart- or kidney-shaped segments strung together. The
plants are more or less incrusted with lime. The branching holdfast
grasps particles of sand, and with them forms a solid ball.
^H. tuna.^ Articulations roundish or half kidney-shaped, one half
to three quarters of an inch broad; frond flat, smooth, and thinner
than most species; bright green; somewhat flexible. (Plate VII.)
[Illustration: PLATE VII. Halimeda tuna. Halimeda tridens. Bryopsis
plumosa. Codium tomentosum.]
[Illustration: PLATE VIII. Caulerpa Mexicana. Caulerpa Wurdemanii.
Caulerpa plumaris. Caulerpa paspaloides.]
^H. tridens.^ Fronds solitary, erect; base composed of
confluent articulations; above divided into numerous branches
of articulations, which are all flat, and in one plane giving a
fan-shaped outline; middle joints wedge-shaped; upper ones divided
into three lobes, frequently bearing articulations at the summit of
each lobe; thinly incrusted with lime; color bright green. (Plate
VII.)
^H. opuntia.^ Articulations kidney-shaped, flat, rather thin;
margins scalloped; irregularly branched and spreading; dense tufts.
ORDER =CODIACEÆ=
GENUS ^Bryopsis^
("/Moss-like/")
There are said to be about twenty species of this genus. They are
distinguished by the manner of branching, but are not very definitely
marked. All are erect, one-celled, branching stalks, and are
feather-like in appearance.
^B. plumosa.^ Fronds branched twice or more; branchlets or pinnules
tapering as they rise on the stalk, giving a triangular outline;
stalk naked below; plants a vivid dark green in color, two to six
inches long, growing in tufts on wharves and stones at low-water
mark and in tide-pools. It is common along the whole Atlantic and
Pacific coasts. It is well to use salt water for mounting this
alga, since the green coloring-matter or granular endochrome with
which it is filled easily escapes. (Plate VII.)
GENUS ^Codium^
^C. tomentosum.^ This is called the commonest seaweed in the world.
It is abundant in every latitude, yet it does not appear on the
eastern coast of North America. It is found on the gulf coast of
Florida and is plentiful on the Pacific coast. The fronds are often
a foot long, composed of closely packed, club-shaped branches
dividing in a forking manner, and densely covered with fine
filaments which give them a soft, sponge-like texture. (Plate VII.)
ORDER =CAULERPACEÆ=
GENUS ^Caulerpa^
(/From two Greek words meaning "stem" and "creep"/)
/Caulerpa/ is the only genus of its order, but it contains about a
hundred species, many of which resemble mosses, ferns, or cacti. Each
plant is composed of a single cell, however much it may be [pg060]
ramified. The frond consists of a prostrate stem, from the lower side
of which root-like fibers or holdfasts descend into the hard sand or
coral, and from the upper side leaf- and branch-like secondary fronds
arise. These plants grow luxuriantly in tropical waters, extending
over large surfaces, and are the chief food of turtles. (Plate VIII.)
^C. prolifera.^ Frond or lamina flat and leaf-like, two to four
inches long, one half to three quarters of an inch wide, either
simple or once forked; margin entire. Similar laminæ spring from
the surface or from the edge or base of the different leaf-like
portions. Laminæ rise from the upper side of the creeping, rooting
stem. Its substance is somewhat horny and translucent.
^C. Mexicana.^ Prostrate, creeping stem, with rootlets or holdfasts
below, and leaf-like fronds above; fronds simple or with one or
two branches deeply cut in narrow lobes nearly to the center. The
species abounds at Key West. (Plate VIII.)
II
OLIVE-GREEN AND BROWN SEAWEEDS (PHÆOPHYCEÆ)
TABLE SHOWING THE CLASSIFICATION OF THE OLIVE-GREEN AND BROWN
SEAWEEDS DESCRIBED IN THIS CHAPTER
Class =ALGÆ=
Subclass =Phæophyceæ= (/Olive-Green and Brown Seaweeds/)
Orders Genera Species
=ECTOCARPACEÆ= ^Ectocarpus^ ^E. littoralis^
^E. siliculosus^
^E. viridis^
^E. tomentosus^
=SPHACELARIACEÆ= ^Sphacelaria^ ^S. cirrhosa^
^S. radicans^
^Cladostephus^ ^C. verticillatus^
=RALFSIACEÆ= ^Ralfsia^
=ENCŒLIACEÆ= ^Punctaria^ ^P. latifolia^
^P. tenuissima^
^P. plantaginea^
^Asperococcus^ ^A. echinatus^
^Phyllitis^ ^P. fascia^
=DESMARESTIACEÆ= ^Desmarestia^ ^D. viridis^
^D. aculeata^
^D. ligulata^
^Arthrocladia^ ^A. villosa^
=DICTYOSIPHONACEÆ= ^Dictyosiphon^ ^D. fœniculaceus^
=ELACHISTACEÆ= ^Elachista^
=CHORDARIACEÆ= ^Chordaria^ ^C. flagelliformis^
^Mesoglœa^ ^M. virescens^
^M. divaricata^
^Leathesia^
^Myrionema^
=LAMINARIACEÆ= ^Chorda^ ^C. filum^
^Alaria^ ^A. esculenta^
^Agarum^ ^A. Turneri^
^Laminaria^ ^L. longicruris^
^L. saccharina^
^L. digitata^
^Macrocystis^
^Nereocystis^
^Lessonia^
^Thalassiophyllum^
=DICTYOTACEÆ= ^Dictyota^ ^D. fasciola^
^D. dichotoma^
^Zonaria^ ^Z. lobata^
^Taonia^ ^T. atomaria^
^Padina^ ^P. pavonia^
^Haliseris^ ^H. polypodioides^
=CUTLERIACEÆ= ^Cutleria^ ^C. multifida^
=FUCACEÆ= ^Himanthalia^ ^H. lorea^
^Fucus^ ^F. vesiculosus^
^F. serratus^
^F. furcatus^
^F. ceranoides^
^Ascophyllum^ ^A. nodosum^
^Phyllospora^ ^P. Menziesii^
^Cystoseira^ ^C. expansa^
^Halidrys^ ^H. osmunda^
^Sargassum^ ^S. vulgare^
^S. Montagnei^
^S. bacciferum^
[pg064]
OLIVE-GREEN AND BROWN SEAWEEDS
This subclass contains some of the most remarkable of the seaweeds.
It is especially notable for the diversity of its plant forms, which
range from filaments to plants which appear to have stems and leaves
(/Sargassum/). The species vary in size from very small fronds to
those of immense size (the /Laminariaceæ/). It includes /Fucus/
(the rockweeds), a very conspicuous genus, which furnishes fully
three fourths of the vegetable covering of the tidal rocks in the
localities in which it grows.
ORDER =ECTOCARPACEÆ=
This order comprises many species of branched, filamentous plants,
some of which are of hair-like fineness and form beautiful feathery
tufts of brownish or olive-green color. They resemble, except in
their tawny color, the green alga /Cladophora/.
The name is derived from Greek words meaning "outside" and "fruit,"
the spores of the plants being borne on the branches.
The species are determined by the arrangement of the spores,
according as they are in the pod-like branches, in groups, or in
cases on stalks. Since these differences are not perceptible to the
naked eye, it is impracticable to describe many species, or for the
amateur collector to try to separate them.
GENUS ^Ectocarpus^
^E. littoralis.^ Filaments fine, in dense tufts, interwoven, six to
twelve inches long; pod linear in the substance of the branches;
color olive-green. This is the most common species of /Ectocarpus/,
and grows abundantly everywhere, appearing like large, fine,
dull-green plumes. (Plate IX.) [pg065]
^E. siliculosus.^ Tufts loosely entangled at the base, free and
feathery above, of indefinite length; spores in pod-like forms at
the ends of the branches. Common on the larger algæ and on wharves.
^E. viridis.^ Tufts a little more loose and expanding than in /E.
siliculosus/; spores in pods at the base of the branches. (Plate
IX.)
^E. tomentosus.^ Fine filaments, densely interwoven into rope-like,
spongy masses, two to four inches long; yellowish-brown; pods on
stalks. Found in summer growing on /Fucus/.
ORDER =SPHACELARIACEÆ=
GENUS ^Sphacelaria^
^S. cirrhosa.^ Olive-brown; branched, feathery filaments, one
half of an inch to two inches long. Each branch ends with an
oblong, swollen cell containing a dark granular mass which gives
it a withered appearance. These cells can be seen with a strong
pocket-lens. It forms dense, globe-like tufts on /Fucus/.
^S. radicans.^ Filaments one half of an inch to one inch high;
branches few and hairy. It forms a dense, grass-like covering, of
indefinite extent, on the under side of muddy rocks. Found on the
New England coast.
GENUS ^Cladostephus^
^C. verticillatus.^ Fronds bristle-like, dividing regularly;
covered with whorls of branchlets set close to the stems, each
whorl overlapping the previous one, giving the plant a spongy
appearance. (Plate IX.)
ORDER =RALFSIACEÆ=
GENUS ^Ralfsia^
The species of this genus are brown, leathery, crustaceous expansions
of indefinite form, one inch to six inches in diameter, resembling
lichens. They appear on rocks in shallow, exposed pools.
ORDER =ENCŒLIACEÆ=
GENUS ^Punctaria^
Dotted-weeds. Fronds pale olive-green, membranaceous, leaf-like, with
short stem; covered with spores which appear like dots.
^P. latifolia.^ Frond pale green, four to twelve inches long, one
inch to five inches wide, leaf-like, and tapering suddenly to a
short stalk; much [pg066] waved on margin; substance soft and
thin; dotted with spores. In the young plants fine hairs emerge
from the dots, but disappear later, and the fronds become darker
and more rigid. Found in summer on rocks and on other algæ on the
Long Island and New England coasts.
^P. tenuissima.^ Fronds smaller and more slender than in /P.
latifolia/; thin and delicate. Found on eel-grass and /Chorda
filum/.
^P. plantaginea.^ Fronds dark brown, leathery, leaf-like, blunt or
wedge-shaped on top; dense clusters of hairs on the dots; six to
twelve inches long, one inch to one and a half inches wide.
GENUS ^Asperococcus^
This genus differs from /Punctaria/ in having a tubular instead of a
flat frond. (Plate IX.)
^A. echinatus.^ Resembles /Enteromorpha/ in being tubular;
compressed or inflated; obtuse at the apex; attenuated at the
base. It differs from /Enteromorpha/ in being olive in color, and
in being covered with small oblong dots of darker shade. When the
plant is young the dots are hairy. It grows in clusters, two to
eighteen inches long, one half of an inch to one inch wide. Common
along the New England coast.
GENUS ^Phyllitis^
^P. fascia.^ Fronds light olive-green, leaf-like, three to six
inches long, one fourth to one half of an inch wide; margin entire,
slightly waved; contracted at base to short stalk; attached
by disk. This species grows in bunches on rocks and stones at
low-water mark, and is very common everywhere. (Plate X.)
ORDER =DESMARESTIACEÆ=
(/Named for M. Desmarest, a French naturalist/)
GENUS ^Desmarestia^
^D. viridis.^ Filaments cylindrical, about as thick as a bristle;
branches opposite, in pairs, at intervals on the main stem. The
branches branch again and continue to be disposed in the same
manner. All are long and ultimately become very fine. The color is
olive-green, becoming verdigris-green when exposed to the air for
a short time or placed in fresh water. The species grows in deep
tide-pools and below low-water mark, forming fine, feathery plumes,
often a yard long, which give submerged rocks the appearance of a
luxuriant garden. (Plate X.)
[Illustration: PLATE IX. Ectocarpus littoralis. Ectocarpus viridis.
Cladostephus verticillatus. Asperococcus bullosus.]
[Illustration: PLATE X. Phyllitis fascia. Desmarestia viridis.
Desmarestia aculeata. Desmarestia ligulata.]
^D. aculeata^ ("spiny"). Fronds cylindrical at base, flattened
above; branches long and straight, arranged alternately, when young
beset with pencils of fine hairs, often one half of an inch long,
which, later, fall off, leaving alternate spines along the edges of
the flattened branches. It [pg067] grows from one foot to six
feet in length, below low-water mark, and is found washed ashore.
It is an attractive plant in the spring, but is brown and coarse
when old. Common everywhere. (Plate X.)
^D. ligulata.^ Fronds two to six feet long, pinnate, having a
flat main stem one half of an inch or more wide, with opposite
flat branches; leaflets arranged along the edges of the branches,
pointed at each end, and bordered with forward-pointing spines. It
is found washed ashore, in abundance, in California, but is not
found on the Atlantic coast. (Plate X.)
GENUS ^Arthrocladia^
^A. villosa.^ Olive-brown filaments, resembling fine, knotted
threads, each knob having a whorl of delicate filaments. It grows
from six inches to three feet long, in deep water. It is rare, but
is occasionally found on the New England coast.
ORDER =DICTYOSIPHONACEÆ=
GENUS ^Dictyosiphon^
^D. fœniculaceus.^ Fronds filiform, bristle-like, branching
into delicate, hair-like branches; yellowish-brown. It resembles
/Chordaria flagelliformis/, but is much finer. (Plate XI.)
ORDER =ELACHISTACEÆ=
GENUS ^Elachista^
The plants of this genus are small, olive-colored, unbranched,
hair-like filaments, growing in dense, radiating tufts, one half
of an inch in height, on /Fucus/. They are interesting to the
microscopist, but not to the collector.
ORDER =CHORDARIACEÆ=
("/Cord-like/")
GENUS ^Chordaria^
^C. flagelliformis^ ("whip-like"). Firm, leathery, somewhat
elastic, slimy strings, six to twenty-four inches long, and twice
as thick as a bristle; branches mostly undivided, short or long,
irregularly placed on the main axis, and curving inward at the
top of the frond; main axis not extending as far as the branches;
blackish in color; attached by a disk to stones and shells;
solitary or in bunches. It is common along the New England coast.
(Plate XI.) [pg068]
GENUS ^Mesoglœa^
^M. virescens.^ Soft, slimy filaments, with branches and
branchlets; olive-green. (Plate XI.)
^M. divaricata.^ Fronds two to twenty-four inches high; branching
irregularly, and generally without definite main axis; branches
flexuous, solid at first, later hollow; branchlets short and
wide-spreading. Common from Cape Cod southward; abundant in Long
Island Sound. (Plate XI.)
GENUS ^Leathesia^
This singular alga resembles a tuber and cannot be mistaken for any
other plant. Its fronds are gelatinous, fleshy balls, one half of an
inch to two inches in diameter, at first solid, afterward lobed and
hollow. It grows singly or in bunches on algæ and on sand-covered
rocks, and is found in summer on every coast. The common species is
known as /L. difformis/ or /L. tuberiformis/.
GENUS ^Myrionema^
Minute algæ which grow on other plants and which appear like dark
spots, or, at first, like stains, on /Ulva/, /Enteromorpha/, and
small red algæ. These spots, which to the naked eye appear like
decay, show, under the microscope, a jelly-like substance full of
beaded filaments.
ORDER =LAMINARIACEÆ=
The plants of this order have large and coarse fronds (some
attaining an immense size), with stems, branching root-like
holdfasts, and expanded leaf-like laminæ. They are leather-like, not
articulated, olive-green or brown in color, and sometimes yellow
and semi-transparent. They grow in deep water and are found washed
ashore. Sometimes small plants are found in deep tide-pools at
low-water mark. Some species are perennial. In these instances the
stems only survive, and the laminæ are reproduced annually. The new
growth takes place at the apex of the stem. The old lamina is pushed
off, but is held on the summit of the new growth until the latter has
matured.
[Illustration: PLATE XI. Dictyosiphon fœniculaceus. Chordaria
flagelliformis. Mesoglœa virescens. Mesoglœa divaricata.]
[Illustration: PLATE XII. Chorda filum. Agarum Turneri. Alaria
esculenta. Laminaria saccharina.]
In the genus /Chorda/ the fronds are cylindrical; in /Agarum/
[pg069] the laminæ are perforated; in /Alaria/ there are wing-like
leaflets below the laminæ.
The /Laminariaceæ/ and /Fucaceæ/ are the seaweeds used in making
kelp. For this the algæ are burned, and the ash is then separated
into its different mineral constituents and used for various
manufacturing purposes.
GENUS ^Chorda^
^C. filum.^ Entire frond cylindrical, divided internally by
transverse septa; one fourth to one half of an inch in diameter,
tapering at each end; ordinarily one to twelve feet long, but
sometimes attaining a length of forty feet. When young the frond
is covered with fine, transparent hairs; later it is brown and
leather-like. The growth takes place at the base, just above the
disk-like holdfast, and at the apex it is constantly dying off. The
species is common on Northern shores, at and below low-water mark.
Often it is in masses which seem like meadows of waving grass under
water. Various small algæ and many zoöphytes are to be found on the
fronds. (Plate XII.)
GENUS ^Alaria^
This genus is readily distinguishable by the fact that it has
leaflets below the lamina. It is found north of Cape Cod.
^A. esculenta.^ Stem compressed, four to twelve inches long, one
fourth to one half of an inch wide, and running like a midrib
through the lamina; lamina one to ten feet long, two to ten inches
wide, frequently torn and ragged; margin wavy; leaflets three to
eight inches long and without midrib, growing on both sides of the
stem, below the lamina. The spores are produced in the leaflets in
the autumn. This is an edible alga and is used as food in Scotland
and Ireland, where it is called henware, badderlocks, murlins, and
so on. (Plate XII.)
GENUS ^Agarum^
The sea-colanders.
^A. Turneri.^ Stem two to twelve inches long, round below,
flattened above, and extending like a midrib through the lamina;
lamina one foot to four feet long, with holes over the whole
surface; margin wavy. The perforations in the lamina are produced
by conical hollow papillæ which cover the young frond and which at
length burst, leaving a hole which enlarges as the plant expands.
This species is found from Cape Cod to Greenland.
There are other species, which differ from this one in the size of
the perforations, the shape of the lamina, and the prominence of
the midrib. Harvey describes the plant as an arctic genus growing
ten to twelve feet long. (Plate XII.) [pg070]
GENUS ^Laminaria^
The plants of this genus are all large, varying from one foot to
twelve feet or more in length. They are of wide geographical range,
and are more numerous in species than any others of the order. They
are commonly known as oarweeds, tangle, devil's-aprons, sole-leather,
kelp, sea-furbelows, and so on.
^L. longicruris^ ("long-stalked"). Stem six to twelve feet long,
one to two inches thick, slender and solid at base, hollow and
inflated at the middle, contracted at the top; attached by a
strong, branching, root-like holdfast; color light brown. The
large, single, leaf-like lamina, usually shorter than the stem, is
five to twenty feet long, two to three feet broad, with much waved
and folded margin, outlined with two rows of depressed spots. The
spores form a band in the center of the blade. Found from Cape Cod
northward and on the Pacific coast.
^L. saccharina^, the sea-tangle. This species differs from /L.
longicruris/ in having a short, solid stem and narrow, ribbon-like
lamina. Stem three inches to four feet long; lamina three to
thirty feet long, six to eighteen inches wide, with central
band of depressed spots; margin much waved; color olive-green,
semi-transparent. It is named from the saccharine matter, called
/mannite/, which it contains. Found on northern shores of the
Atlantic and the Pacific oceans. (Plate XII.)
^L. digitata^ ("fingered"). Stem one to five feet long, thick,
round, and solid; lamina oval at base, leathery, smooth, brown,
deeply cleft into segments of unequal breadth. It is named from the
hand-like form of the lamina. This species is found in Long Island
Sound, but is not common south of Cape Cod. The stem is used by
fishermen for knife-handles. Pieces of it, placed on the blades
while green, contract in drying and become solid. (Plate XIII.)
For the genera ^Macrocystis^, ^Nereocystis^, ^Lessonia^, and
^Thalassiophyllum^, see the Introduction, pages 35, 36.
ORDER =DICTYOTACEÆ=
GENUS ^Dictyota^
^D. fasciola.^ Fronds olive-brown, expanded, membranaceous, erect,
flat; many times forked narrow branches; grows in tufts six to ten
inches long, matted at the base.
^D. dichotoma.^ Same as /D. fasciola/, except that the divisions of
the forked frond are one eighth to one half of an inch wide. Found
in tide-pools in Southern waters. (Plate XIII.)
[Illustration: PLATE XIII. Laminaria digitata. Dictyota dichotoma.
Taonia atomaria. Padina pavonia.]
[Illustration: PLATE XIV. Haliseris polypodioides. Cutleria
multifida. Fucus vesiculosus.]
GENUS ^Zonaria^
^Z. lobata.^ Thallus flat, fan-shaped, but not so rounded as
in /Padina pavonia/, twelve or more inches in height, cleft
irregularly into many [pg071] narrow lobes, the clefts
extending nearly or quite to the base; olive-green, with concentric
zones of darker color; edges thin and bordered with a dark line.
Found in southern California and in tropical and subtropical seas.
GENUS ^Taonia^
^T. atomaria.^ Spreading, fan-shaped frond; clefts irregular and
not extending to the basal stem; spores arranged in dark wavy
lines and spots on the frond, giving it a mottled appearance and
beautiful gradation of color. Found in tropical seas. (Plate XIII.)
GENUS ^Padina^
^P. pavonia^, the peacock's-tail. Frond broadly fan-shaped;
substance between membranaceous and leathery; powdery on the
outer surface; deeply and variously cleft or entire; several
laminæ emanating from a stalk-like base; each lamina fan-shaped;
concentric lines numerous; variegated in zones. This beautiful alga
is always regarded as a prize. It is found on stones at low-water
mark, and is not uncommon south of Charleston, South Carolina, but
is more luxuriant in tropical seas. (Plate XIII.)
GENUS ^Haliseris^
The sea-endive.
^H. polypodioides.^ Fronds flat, forked, notched on lower part;
divisions about one quarter of an inch wide; distinct midrib;
olive-green; grows in tufts. It is found in North and South
Carolina, and is abundant on the Florida Keys. (Plate XIV.)
ORDER =CUTLERIACEÆ=
GENUS ^Cutleria^
^C. multifida.^ Frond erect, flat; branches in a forking manner;
ultimate branches fine and short, and with branchlets on the tips.
This species resembles /Taonia/. It is found in Southern waters.
(Plate XIV.)
ORDER =FUCACEÆ=
GENUS ^Himanthalia^
^H. lorea^, the sea-thong. A cup-shaped base, from the center of
which arises a flat, strap-like frond one fourth to one half of an
inch wide and two to twenty feet long, branching dichotomously (or
by forking), and dotted with pits, or conceptacles, in which the
spores are formed. Found in the extreme North. [pg072]
GENUS ^Fucus^
The rockweeds. The plants of this genus grow in thick bunches, and
are found in great abundance between tide-marks. The plants are
attached by sucker-like disks to the rocks, from which they hang like
fringe when the tide recedes; when it rises they float and sway in
the water in beautiful bouquet-like forms. In color they are brown or
olive-green, in texture thick and leathery, but they sometimes expand
into thin membranes. They are many times forked in the same plane,
which produces a flat thallus. They often have a distinct midrib. The
air-vessels, whose function it is to float the plant, are disposed
along the midrib, usually in pairs.
The species are named according to the divisions of the frond,
and the disposition, or presence, of the air-bladders and the
/conceptacles/, or spore-chambers.
The conceptacles congregate in particular portions of the frond and
give its surface a roughness which is very perceptible; such portions
are then known as the /receptacles/. In /Fucus/ this usually occurs
on the bulbous extremities of the branches. Under the microscope a
section of one of these little pointed spots shows a spherical cavity
filled with a beautiful arrangement of /paraphyses/, or threads,
some of which hold spores, while others protrude through a small
opening in the outer membrane. Conceptacles are peculiar to the
order =Fucaceæ=. In them spore-production is carried on in a manner
as complicated as is the formation of seeds in flowering plants.
Although rockweeds are such a conspicuous feature of sea-shore
vegetation, two species only, /Fucus vesiculosus/ and /Ascophyllum
nodosum/ (formerly called /Fucus nodosus/), are common on the
Atlantic coast, and these do not occur south of New York, owing to
the fact that a long stretch of sand-beach extends beyond that point.
^F. vesiculosus.^ Midrib distinct through all the forked branches;
margin entire, often wavy; air-vessels spherical or oblong, usually
in pairs along the midrib; receptacles on terminal branches, which
are swollen and filled with gelatinous matter, heart-shaped or
forked, in oblong or pointed divisions; frond tough and leathery,
often two feet long. (Plate XIV.)
[Illustration: PLATE XV. Fucus serratus. Fucus ceranoides.
Ascophyllum nodosum.]
[Illustration: PLATE XVI. Phyllospora Menziesii. Halidrys osmunda.
Sargassum vulgare.]
^F. serratus.^ Frond distinctly toothed or serrated along the
margin; midrib conspicuous through the main axis and forked
branchings; no air-vessels. This species is rare on the Atlantic
coast. (Plate XV.)
^F. furcatus.^ Frond narrow, tough, without air-vessels; regular
forked branching; midrib distinct below, inconspicuous above;
receptacles long, narrow, not inflated. Found from Boston northward.
^F. ceranoides.^ Frond flat, rather membranaceous, or less leathery
than in the preceding species; repeatedly forked; midrib not
running through every division; no air-vessels. (Plate XV.)
GENUS ^Ascophyllum^
^A. nodosum.^ This species, formerly called /Fucus nodosus/, is
next to /Fucus vesiculosus/ the most common rockweed. Frond one to
five feet long, dark brown, strap-like, leathery; width of main
stems one fourth of an inch or more, and uniform throughout; large,
single, oblong air-vessels distend the frond at intervals. Branches
of various length emerge from the sides of the main stem. Ovoid or
ellipsoidal branchlets or receptacles, single or in groups, occur
at intervals along the sides of both stem and branches. These fall
off after a time and are found in quantities in tide-pools. (Plate
XV.)
GENUS ^Phyllospora^
^P. Menziesii.^ Branching holdfast; short stem which immediately
divides into strap-like branches; branches edged with leaves
varying in length, rounded at top, narrow, stalked at base; leaves
placed at intervals, or crowded together, and interspersed with
air-vessels which are often tipped with leaflets; stems expand at
summit into leaf-like laminæ and are edged with leaflets at the
base; plant often one hundred and twenty feet or more in length;
tough and leathery in substance. Very common on the California
coast. (Plate XVI.)
GENUS ^Cystoseira^
^C. expansa.^ Frond long, slender, repeatedly branched; air-vessels
ellipsoidal and "chained" together in the lower half of the
branches. The plant grows in deep water, ad shows iridescent colors
when seen through the water. It is found on the California coast.
GENUS ^Halidrys^
^H. osmunda^, the sea-oak. Frond flat, alternately toothed
or indented below; branched apex, bearing air-vessels like
long-stalked pods; substance leathery. Found on the coast of
southern California. (Plate XVI.)
GENUS ^Sargassum^
^Sargassum^ is distinguished by its differentiation into stem and
leaf, resembling in outward appearance the higher plants. It [pg074]
is a tropical and subtropical genus, and has one hundred and fifty
species. Two of these, /S. vulgare/ and /S. Montagnei/, are found as
far north as Cape Cod. See Introduction, page 34.
^S. vulgare.^ Stems cylindrical; branches alternate; leaves long,
narrow, toothed, with short stalk and midrib; minute dark spots
on its surface; air-vessels small balls resembling berries set on
stalks and usually tipped with a long point; receptacles small,
twig-like forms in the axils of the leaves; color olive-brown;
plant one foot to three or more feet long. Common in Long Island
Sound. (Plate XVI.)
^S. Montagnei.^ This species resembles /S. vulgare/, but is more
slender in all its parts, and the receptacles are more elongated.
From south of Cape Cod.
^S. bacciferum.^ Particular interest attaches to this species from
the fact that it is the one which forms the floating vegetation
of the Sargasso Sea. It grows attached on the Florida Keys and in
the West Indies. Specimens are sometimes carried by the currents
northward, and are found washed ashore. It differs from /S.
vulgare/ in the leaves, which are thicker, more attenuated, and
sharply toothed, and in having a greater number of air-vessels.
A branch of this species brought from the Sargasso Sea had
air-vessels so numerous and closely set that it resembled a bunch
of small grapes.
III
RED SEAWEEDS
(RHODOPHYCEÆ OR FLORIDEÆ)
TABLE SHOWING THE CLASSIFICATION OF THE RED SEAWEEDS DESCRIBED IN
THIS CHAPTER
Class =ALGÆ=
Subclass =Rhodophyceæ or Florideæ= (/Red Seaweeds/)
Order =NEMALIONACEÆ=
Suborders Genera Species
~HELMINTHOCLADIEÆ~ ^Nemalion^ ^N. multifidum^
^Liagora^
~CHÆTANGIEÆ~ ^Scinaia^ ^S. furcellata^
~GELIDIEÆ~ ^Gelidium^ ^G. corneum^
Order =GIGARTINACEÆ=
^Chondrus^ ^C. crispus^
^Gigartina^ ^G. mamillosa^
^G. radula^
^G. spinosa^
^G. microphylla^
^Phyllophora^ ^P. membranifolia^
^P. Brodiæi^
^Sternogramme^ ^S. interrupta^
^Gymnogongrus^ ^G. Norvegicus^
^Ahnfeldtia^ ^A. plicata^
^Callophyllis^ ^C. variegata^
^C. laciniata^
^Iridæa^
Suborders Genera Species
~RHODOPHYLLIDEÆ~ ^Cystoclonium^ ^C. purpurascens^
^C. cirrhosa^
^Euthora^ ^E. cristata^
^Rhodophyllis^ ^R. veprecula^
^Rhabdonia^ ^R. tenera^
^R. Coulteri^
^Eucheuma^ ^E. isiforme^
Order =RHODYMENIACEÆ=
~SPHÆROCOCCEÆ~ ^Gracilaria^ ^G. multipartita^
^Hypnea^ ^H. musciformis^
~RHODYMENIEÆ~ ^Rhodymenia^ ^R. palmata^
^Lomentaria^ ^L. Baileyana^
^Champia^ ^C. parvula^
^Chylocladia^ ^C. articulata^
^Plocamium^ ^P. coccineum^
~DELESSERIEÆ~ ^Nitophyllum^ ^N. laceratum^
^N. Ruprechteanum^
^N. punctatum^
^Grinnellia^ ^G. Americana^
^Delesseria^ ^D. sinuosa^
^D. alata^
^D. Leprieurii^
~RHODOMELEÆ~ ^Polysiphonia^ ^P. fastigiata^
^P. nigrescens^
^P. parasitica^
^P. dendroidea^
^P. Baileyi^
^P. Harveyi^
^P. Olneyi^
^P. fibrillosa^
^P. violacea^
^P. urceolata^
Var. ^formosa^
^P. variegata^
^P. Woodii^
^Laurencia^ ^L. pinnatifida^
^Dasya^ ^D. elegans^
^D. plumosa^
^Bostrychia^ ^B. rivularis^
^Rhodomela^ ^R. subfusca^
^R. Rochei^
^R. larix^
^R. floccosa^
^Chondria^ ^C. dasyphylla^
^C. tenuissima^
^C. striolata^
Suborders Genera Species
~CERAMIEÆ~ ^Callithamnion^ ^C. americanum^
^C. Pylaisæi^
^C. Baileyi^
^C. seirospermum^
^C. byssoideum^
^C. floccosum^
^Griffithsia^ ^G. Bornetiana^
^Ptilota^ ^P. serrata^
^P. elegans^
^P. densa^
^P. hypnoides^
^Spyridia^ ^S. filamentosa^
^Ceramium^ ^C. rubrum^
Var. ^proliferum^
Var. ^secundatum^
^C. strictum^
^C. diaphanum^
^C. fastigiatum^
^C. tenuissimum^
Var. ^patentissimum^
^Microcladia^ ^M. Coulteri^
^M. borealis^
Order =CRYPTONEMIACEÆ=
~GLOIOSIPHONIEÆ~ ^Gloiosiphonia^ ^G. capillaris^
~GRATELOUPIEÆ~ ^Halymenia^ ^H. ligulata^
^Grateloupia^ ^G. Cutleria^
^Prionitis^ ^P. lanceolata^
^P. Andersonii^
~DUMONTIEÆ~ ^Pikea^ ^P. Californica^
^Halosaccion^ ^H. ramentaceum^
~RHIZOPHYLLIDEÆ~ ^Polyides^ ^P. rotundus^
~SQUAMARIEÆ~ ^Peyssonnelia^ ^P. Dubyi^
^Petrocelis^ ^P. cruenta^
^Hildenbrandtia^ ^H. rosea^
~CORALLINEÆ~ ^Corallina^ ^C. officinalis^
^Melobesia^
Order =BANGIACEÆ=
^Bangia^ ^B. fusco-purpurea^
^Porphyra^ ^P. vulgaris^
^P. laciniata^
[pg079]
RED SEAWEEDS
In =Rhodophyceæ=, known also as =Florideæ= and =Rhodospermeæ=,
algæ attain their highest development. This is marked by the mode
of reproduction, which, more nearly than in the other subclasses,
resembles that of flowering plants. The fronds, however, are not as
large and do not as closely resemble stem and leaf as do some species
of the brown algæ.
The species of this subclass are very numerous, and the variety in
their fronds, their delicate texture, and their colors, which vary
from pink to purple, make them the most attractive of the seaweeds.
They grow mostly in deep water, but are often found washed ashore,
and many grow just below low-water mark and on the shady side of
tide-pools.
In the simplest species the frond consists of branched cell-rows.
In some of these the filaments are so fine that a pocket-lens is
required to determine the differences in branching and fully to
appreciate the beauty of the plant (/Callithamnion/). Some have a
cell-surface. In /Delesseria/ the membrane assumes the outline of a
foliage-leaf. /Dasya/, which is an abundant variety, is especially
beautiful in its feather-like appearance. The corallines are singular
in that they are incrusted with lime and resemble corals.
ORDER =NEMALIONACEÆ=
SUBORDER ~HELMINTHOCLADIEÆ~
GENUS ^Nemalion^
The threadweeds.
^N. multifidum.^ Frond six to twelve inches long, cylindrical,
solid, cord-like, elastic, tough, shiny, very gelatinous; branches
repeatedly in [pg080] a wide-forking manner; sometimes a branch
will divide into several parts at the same point; color dark brown
or purple. It is found, in summer only, from Long Island Sound
northward, growing on smooth rocks which are exposed to the action
of the waves.
GENUS ^Liagora^
Fronds filamentous; branching regularly in a forking manner to the
very top, forming thick bunches; slightly incrusted with lime, yet
somewhat viscid. It is found in Florida and California, and abounds
in tropical waters.
SUBORDER ~CHÆTANGIEÆ~
GENUS ^Scinaia^
^S. furcellata.^ Frond cylindrical, one eighth of an inch in
diameter, tapering at base, sometimes constricted at intervals,
regularly and several times forked, ending in short divisions;
branches of same length, giving a level top; two to four inches
high; lake-red. When pressed the axis is visible, giving the
appearance of a flat frond with a midrib. This species is found
in summer only, washed ashore from Cape Cod southward and on the
California coast. It is not common. (Plate XVII.)
SUBORDER ~GELIDIEÆ~
GENUS ^Gelidium^
^G. corneum.^ Frond flat and horny, one inch to four inches high,
narrow, erect, branched several times in the same plane; ultimate
branchlets club-shaped, or swollen at the tips with masses of
spores; color purple-red. It grows in tufts on mud-covered rocks,
and on algæ at low-water mark. The typical form is found in Florida
and on the Pacific coast. Smaller plants are found all along the
Atlantic shore. It is an extremely variable plant, and is often
difficult to distinguish on this account. (Plate XVII.)
[Illustration: PLATE XVII. Scinaia furcellata. Gelidium corneum.
Gelidium Coulteri. Chondrus crispus.]
ORDER =GIGARTINACEÆ=
GENUS ^Chondrus^
Carrageen or Irish moss.
^C. crispus.^ Frond begins with flattened stem, which divides and
subdivides many times in a broad-forked, fan-like manner; varies
greatly in length and breadth of divisions, also in size and color,
according to conditions of its habitation. In shallow tide-pools
it is pale and [pg081] stunted; but under the shelter of
rocks, in deep water, it grows in dense masses and is a dark
purplish-red or reddish-green. Often it appears iridescent when
seen through the water, with the sun shining on it. It is firm and
leathery in substance. It is an edible alga, and was formerly very
generally used for culinary purposes. At Hingham, Massachusetts,
large quantities are gathered as an article of commerce. It is a
beautiful and very common plant found from New York northward.
(Plate XVII.)
GENUS ^Gigartina^
Of the species of this genus but one is found on the eastern coast;
on the Pacific coast there are several, and they are large and
conspicuous.
[Illustration: PLATE XVIII. Gigartina mamillosa. Gigartina radula.
Gigartina spinosa. Gigartina microphylla.]
^G. mamillosa.^ Frond three to six inches high, one inch to two
inches broad, flat, leathery, gelatinous; forking near the base,
then dividing and subdividing in the same plane; segments more or
less wedge-shaped and with a tendency to roll inward; covered with
numerous small nipple-like protuberances which contain the spores.
These projections distinguish this genus from /Chondrus/, which it
otherwise resembles, and with which it grows. The color is dark
purple. It is found from Boston northward. (Plate XVIII.)
^G. radula.^ Frond flat and thick; rising from a short stem
and widening to several inches; sometimes tapering to the top,
sometimes blunt or divided, sometimes cleft on the sides, but
usually simple; covered with wart-like projections; color dark,
livid red. It is found on the Pacific coast at all seasons, growing
on rocks between tide-marks. Large specimens are one foot to three
feet long and six to ten inches wide. (Plate XVIII.)
^G. spinosa^ ("thorny"). Frond thick, leathery; surface rough and
spiny; form variable, the divisions sometimes emanating from a
broad, flattened base, or again branching from a main axis; all
covered with the protruding processes peculiar to the genus; color
dark red, brown, or purple. It is found on the California coast.
(Plate XVIII.)
^G. microphylla^ ("small-leaved"). Plant rises from short, flat
stem, and rapidly expands into a flat, wide, thin frond which is
simple or divided into two or three segments, each of which tapers
into a long, pointed apex; thickly covered with long, slender
spines, and on its edges bearing small, thin leaflets; color
brownish-red. It is abundant on the California coast. (Plate XVIII.)
GENUS ^Phyllophora^
Leafweed. Fronds cylindrical; branched stalks which expand into
rigid, membranaceous, simple or cleft, wedge-shaped laminæ; laminæ
bear leaflets on their edges or on their surface; spores in masses
form projections on the surface, or are on stalks at the summit;
color dark red. Found washed ashore from New York northward. [pg082]
^P. membranifolia.^ Several stems rise from same disk; branches
expand into wedge-shaped, cleft or forked laminæ; lobes bear on the
summit other laminæ or leaflets divided in the same manner.
^P. Brodiæi.^ Stem less branched and leaf-expansions broader and
larger than in /P. membranifolia/; laminæ wedge-shaped and deeply
lobed. (Plate XIX.)
GENUS ^Sternogramme^
^S. interrupta.^ Frond a thin membrane repeatedly forked, widely
spreading, divisions one fourth to one half of an inch wide;
fertile plants have the spores arranged in an interrupted line
through the center of the segments resembling a midrib; frond two
to eight inches high; bright red. It is found on the California
coast. The illustration shows a plant on which the hydroid
/Sertularia pumila/ is growing. (Plate XIX.)
GENUS ^Gymnogongrus^
^G. Norvegicus.^ Frond two to four inches high, thin but leathery
in substance, flat, narrow, divided in a regular forking manner;
spreading ends of terminal forks obtuse; axils rounded; spores form
spherical masses in the upper segments, and project on both sides
like hemispheres. It resembles a simple form of /Chondrus crispus/,
but is more delicate. The color is red or purple. This species is
found in deep tide-pools from New York northward. (Plate XIX.)
GENUS ^Ahnfeldtia^
^A. plicata.^ Frond coarse, stem-like filaments, stiff, wiry,
irregularly and profusely branched; sometimes regularly forked and
upper segments equal; entangled; six to eight inches long; tufts
several inches in diameter; dark purple or black. Specimens long
exposed on the beach are faded to white. It is very common from New
York northward. (Plate XIX.)
GENUS ^Callophyllis^
^C. variegata.^ Deeply cleft, wide-spreading, flat, membranaceous
frond; all parts notched more or less angularly; color dark to
bright red; spores form hemispherical warts on surface. Some
varieties differ from this one in having long and narrow, and
others in having short and broad segments. It is a beautiful and
common alga on the Pacific coast, resembling /Euthora/ of the
eastern coast. (Plate XX.)
^C. laciniata.^ Frond deeply cleft; segments wedge-shaped. It is
found on the Pacific coast. (Plate XX.)
[Illustration: PLATE XIX. Phyllophora Brodiæi. Sternogramme
interrupta. Gymnogongrus Norvegicus. Ahnfeldtia plicata.]
[Illustration: PLATE XX. Callophyllis variegata. Callophyllis
laciniata. Iridæa. Cystoclonium cirrhosa.]
GENUS ^Iridæa^
Frond rises from stalk and widens into a flat, thick, leathery, oval
expansion, one to two feet long, and one to three inches broad;
[pg083] simple or lobed; surface sometimes roughened by collections
of spores in dots; dark red, often glittering in the water with blue
and purple tints. It is found on the Pacific coast. (Plate XX.)
SUBORDER ~RHODOPHYLLIDEÆ~
GENUS ^Cystoclonium^
^C. purpurascens.^ The translucent, fleshy, juicy main stem, one
eighth of an inch or less in diameter, runs through the whole
plant; irregularly branched all around main stem; branches again
branch in same manner; branches attenuated at the base, and taper
to a long point; smaller branches distended in places by spores
into bladder-like swellings, hence the name; color rose-red to
dark purple; plants exposed on the beach often faded to orange
and white; six to eighteen inches long. It grows on rocks between
tide-marks as well as in deep water. With the exception of
/Ceramium rubrum/, this is the most common red alga on the eastern
coast from New York northward. It differs from /Rhabdonia/ in
having bladdery branches; otherwise it is easily mistaken for it.
^C. cirrhosa.^ Ends of branches terminate in spirals like tendrils;
otherwise identical with /C. purpurascens/. (Plate XX.)
GENUS ^Euthora^
^E. cristata.^ Frond one inch to five inches high, membranaceous,
broadly spreading; divisions wide and numerous, ultimately becoming
fine like minute branchlets, each one of which, under a glass,
shows a notch in the tip. This beautiful, bright-red alga is found
in abundance north of Cape Cod. It differs from /Delesseria alata/
in having no midrib or veins. It grows in deep water on stones,
shells, and algæ. (Plate XXI.)
GENUS ^Rhodophyllis^
("/Rosy leaf/")
^R. veprecula.^ Frond two to five inches long, one fourth of an
inch to one and one half inches broad, membranaceous, forked;
margin covered with leaflets which are in turn edged with minute
branchlets; color deep red. It is found on the northern New England
coast. (Plate XXI.)
GENUS ^Rhabdonia^
("/A wand/")
^R. tenera.^ Frond six to eighteen inches long, cylindrical,
fleshy, translucent, juicy; irregularly and profusely branched,
branches longest at the base, erect, tapering at both ends,
numerous branchlets; sometimes the main stem runs through
the plant, sometimes it is lost in the [pg084] branching;
spore-masses sometimes form knotty bunches on the side of
branches. It resembles a large /Cystoclonium purpurascens/. It is
characteristic of Long Island Sound, and is not found north of
Cape Cod, but common from there southward along the whole Atlantic
coast. (Plate XXI.)
^R. Coulteri.^ This species is common on the Pacific coast, and
differs from /R. tenera/ in having a more pronounced leading stem,
and branches shorter and crowded at the top of the frond.
GENUS ^Eucheuma^
^E. isiforme.^ Frond grows in tufts a foot or more in diameter;
stems branch in all directions from a central point, and taper
gradually to the end; secondary branches spread to all sides;
all branches swollen at intervals and armed with several spines
spreading from a conical base; color dark red, becoming on exposure
orange or yellow, and at length semi-transparent and horn-like;
substance firmly cartilaginous. Abundant at Key West.
ORDER =RHODYMENIACEÆ=
SUBORDER ~SPHÆROCOCCEÆ~
GENUS ^Gracilaria^
^G. multipartita^ ("many times divided"). Frond four to twelve
inches long; starting from a short, cylindrical stem, it flattens
and broadens as it rises, dividing in an irregular, forking manner,
or cleft into palmate segments which broaden as they rise, and
which divide in the same manner; often cleft or branched on the
edges; conical spore-masses scattered over the frond during July
and August; dingy purple in color. The plant is variable and
sometimes is difficult to determine. It is common from Cape Cod
southward. A narrow variety is most abundant in Long Island Sound.
In Florida and on the California coast there are broad varieties
which may be mistaken for /Rhodymenia/. (Plate XXI.)
GENUS ^Hypnea^
^H. musciformis^ ("moss-like"). Frond six to twelve inches long;
main stem running through, thick below and tapering to the size of
a bristle; much and irregularly branched, especially at the base;
branches wide-spreading in every direction, and longest at the
base; branches branch again in the same manner; all parts beset
with short, horizontal spines; color purplish-red. A characteristic
feature, by which the plant can easily be distinguished, is that
the ends of the long branches are naked and are turned over like a
hook, or nearly twisted. It is found washed ashore, often in large,
intricately twisted tufts, from Cape Cod southward and on the
Pacific coast.
[Illustration: PLATE XXI. Euthora cristata. Rhodophyllis veprecula.
Rhabdonia tenera. Gracilaria multipartita.]
[Illustration: PLATE XXII. Rhodymenia palmata. Rhodymenia palmata.
Lomentaria Baileyana. Chylocladia articulata.]
SUBORDER ~RHODYMENIEÆ~
GENUS ^Rhodymenia^
("/Red membrane/")
^R. palmata^ ("hand-shaped"). The plant commonly known as dulse.
Frond rises from a disk in a short cylindrical stem which spreads
into a thin, broad, fan-shaped membrane six to twelve inches long
and four to eight inches wide at the top; deeply and irregularly
cleft into many wedge-shaped segments; margin usually entire, but
often with leaflets; ends of segments indented, showing where
divisions will ultimately occur; color dark purplish-red. It grows
on rocks and on algæ below low-water mark, and is common on the New
England and California coasts. This is an edible alga, and, like
/Chondrus crispus/, is an article of food in seaports. (Plate XXII.)
GENUS ^Lomentaria^
^L. Baileyana.^ Fronds two to five inches high; grows in tufts;
filaments tubular, irregularly branched; branchlets often all on
one side; branches and branchlets curved or arched, and tapered at
both ends; color brownish-red. It is found washed ashore from Cape
Cod southward. (Plate XXII.)
GENUS ^Champia^
^C. parvula.^ Frond two to six inches long, irregularly branched;
grows in tufts; filaments hollow and constricted, so that they
appear somewhat like a string of beads; color brownish-purple. It
is found washed ashore from Cape Cod southward. (Plate XXIII.)
GENUS ^Chylocladia^
^C. articulata.^ Frond filamentous, three to twelve inches long,
hollow, constricted at intervals; branches emanate from constricted
joints; has the appearance of a series of pink, delicate, oval
sacs. (Plate XXII.)
GENUS ^Plocamium^
^P. coccineum^ ("scarlet"). Frond a flat, semi-cartilaginous main
stem one eighth of an inch, or less, wide, three to eight inches
long, with alternate branches of unequal length emanating from the
edges; branches have alternate branchlets arranged in groups of
three or four in a row; branchlets have pinnulæ on the upper side,
like the teeth of a comb (this peculiarity in branching makes the
genus easy to identify); color dark lake-red. It is not found on
the eastern coast, but is plentiful in California. (Plate XXIII.)
SUBORDER ~DELESSERIEÆ~
GENUS ^Nitophyllum^
^N. laceratum.^ Frond expands from narrow base and divides almost
at once into long, narrow, strap-shaped segments; minute leaflets,
showing [pg086] a dot or spore-cluster, occur at intervals on the
margin; plant six to eight inches long; thin and silky in texture.
Abundant on the California coast. (Plate XXIII.)
^N. Ruprechteanum.^ Frond one foot to two feet long, spreading
from narrow base and dividing by forking into deep-cut, broad,
strap-like lobes; top divisions rounded; traversed lengthwise by
parallel veins; margin of the older parts bordered with a narrow
frill of thin ruffled membrane which sometimes extends also over
parts of the surface of the frond; substance somewhat rigid; color
dark red to purple. It is found on the California coast. (Plate
XXIV.)
^N. punctatum.^ Frond six to twenty inches long and of the same
width, dividing in a forking manner; crowded at top; when in fruit,
covered with dark dots; substance thin and silky; color rose-pink.
It is found on the California coast. (Plate XXIV.)
GENUS ^Grinnellia^
(/Named for Mr. Henry Grinnell of New York/)
^G. Americana.^ Frond a delicate membrane, rose-red or purplish in
color, leaf-shaped, four to eight inches long, one inch to four
inches wide, tapering at both ends; margin entire, but much waved;
a line of darker color through the center resembles a midrib;
masses of spores form dots or specks irregularly over the whole
surface; grows from a disk and short slender stem in bunches on
shells and stones in deep water. It is found washed ashore from
Cape Cod southward, and is luxuriant in New York Bay, where it can
be found at any season, but is in perfection in August. (Plate
XXIV.)
GENUS ^Delesseria^
^D. sinuosa.^ Delicate, leaf-like membrane, with midrib and veins,
much indented and resembling in general outline an oak-leaf; four
to eight inches long, two to four inches broad; short stem; color
dark red, often flecked with green. It grows in bunches in deep
water, and is easily distinguished, since it is the only alga
having a midrib and veins, and resembling the leaf of a tree. It is
found washed ashore from Cape Cod northward. (Plate XXIV.)
^D. alata^ ("winged"). Frond rises from short stem, which flattens
and divides irregularly into many branches and appears like a
midrib, all bordered with narrow membrane one eighth of an inch to
one inch wide; frond two to four inches long; color light red or
pink. It is found on the shore from Cape Cod northward. (Plate XXV.)
^D. Leprieurii.^ Frond one inch to two inches long, very narrow,
with delicate midrib, forked, constricted at intervals; branches
start from constricted points; thin and delicate; color purple.
It is found in tidal rivers near New York, and is common on the
southern coast. (Plate XXV.)
[Illustration: PLATE XXIII. Champia parvula. Champia parvula,
magnified. Plocamium coccineum. Nitophyllum laceratum.]
[Illustration: PLATE XXIV. Nitophyllum Ruprechteanum. Nitophyllum
punctatum. Grinnellia americana. Delesseria sinuosa.]
[Illustration: PLATE XXV. Delesseria alata. Delesseria Leprieurii.
Polysiphonia fastigiata (on Ascophyllum). Polysiphonia parasitica.]
[Illustration: PLATE XXVI. Polysiphonia dendroidea. Polysiphonia
dendroidea, a piece magnified. Polysiphonia Harveyi. Polysiphonia
Harveyi, a piece magnified.]
SUBORDER ~RHODOMELEÆ~
The genera included in this suborder are easily distinguished when in
fruit by the spore-cases, or cystocarps, which appear [pg087]
like little balls, either adherent to the branches, or raised on
short stalks. It is the largest group, and contains many of the most
beautiful of the red algæ.
GENUS ^Polysiphonia^
("/Many tubes/")
A filament of ^Polysiphonia^ appears, when seen under the microscope,
like a bundle of filaments made up of a central tube, or axis,
surrounded by a number of other tubes. It is by the number of these
parts, called siphons, which vary in number from four to twenty, that
the species is determined. In some plants the siphons are surrounded
by a layer of cells, called corticating or bark cells, which give
the filaments a solid, uniform appearance. In others the siphons are
naked, and the filaments then seem striped or banded with color. It
is difficult, without a microscope, to be sure of the classification.
There are, however, other characteristics which separate many of the
species, and some of these are described below. Two hundred species
of /Polysiphonia/ have been named by algologists. The plants are
plentiful on all shores, especially in warm, shallow waters. Some
species are perennial, but most of them are annuals and disappear in
winter.
^P. fastigiata.^ This species grows on /Ascophyllum nodosum/ in
a globular tuft, and appears like a dark-brown ball, one inch
to three inches in diameter. The frond is a dense mass of rigid
filaments branching many times in a forking manner and at broad
angles. The ends are of nearly equal length, giving the plant
a spherical shape. It is common from New York northward at all
seasons, and is easily recognized by its general form and place of
growth. Egg-shaped cystocarps, or spore-cases, occur in the ends of
the terminal filaments. (Plate XXV.)
^P. nigrescens.^ Frond three to twelve inches long, rigid below,
soft above; main stem thick as a bristle, but not always easy to
distinguish; branches alternate and densely branched at the ends;
siphons twelve to sixteen in number; filaments banded; color black
or very dark brown. (Plate XXVII.)
^P. parasitica.^ Frond one inch to three inches long; branched in
a pinnate or feather-like manner; filaments flat; all branches
and branchlets emanating from the edges and on the same plane,
giving a flat frond; color reddish-brown; resembles a fine /Ptilota
plumosa/; cystocarps on short stalks. It is found on the California
coast. (Plate XXV.)
^P. dendroidea.^ This is a variety of the species /P. parasitica/.
Frond four to five inches long; main branches placed at irregular
intervals, but the secondary branches at regular intervals and
alternate; branches [pg088] set at acute angles, giving the plant
a slender appearance; color black or dark brown. It is common on
the California coast. (Plate XXVI.)
^P. Baileyi.^ Frond three to six inches high, flat; branches
emanate from edges of the flat stems; main branches wide-spreading
and irregularly placed, secondary branches regular and alternate;
branchlets one eighth to one half of an inch long, covered on the
edges and around the top with incurved ramuli; branchlets broken
off near the base of the branches in mature plants; branchlets
usually uniform in length, but occasionally one is longer and
branches like the primary stem; color black. Common on the
California coast.
^P. Harveyi.^ Frond two to six inches high; grows in globose tufts,
and has a bushy aspect; branches stiff and wide-spreading; stems
and branches beset with simple or branched spine-like branchlets;
color dark brown, or black when dry; does not collapse when taken
from the water; cystocarps on short stalks; siphons four in number.
It grows on eel-grass and algæ, and is common in Long Island Sound
and northward. Called locally /niggerhair/. (Plate XXVI.)
^P. Olneyi^ (dough-balls). Fronds two to five inches high, densely
tufted; soft filaments of hair-like fineness, much branched, and
spreading; when in fruit covered with tiny balls or cystocarps;
siphons four in number. It is common from Cape Cod to New York.
^P. fibrillosa.^ Frond four to ten inches high, rather robust
below; main stem quickly lost in a number of prominent stems and
spreading branches; irregularly and profusely branched, becoming
ultimately very fine; numerous branchlets covered with colorless
fibrils in hairy tufts, which give it a misty appearance; fibrils
so delicate that they do not show well in dried specimens, but a
distinct feature by which to recognize the species in the young
plant; color light to dark brown; cystocarps adherent to branchlets
or on short stalks; siphons four in number; main branches only
corticated. It is common in summer on stones and on eel-grass, at
low-water mark, from Cape Cod to New York. (Plate XXVII.)
^P. violacea.^ Fronds six to twenty-four inches high, pyramidal
in general outline; main axis with long, wide-spreading branches
at the base; branches rather robust and naked below, but numerous
and becoming very fine and tufted at top; cystocarps adherent or
on short stalks; siphons four in number; main stems corticated;
ultimate branchlets show articulations; color brownish-red. It is
common from New York northward. (Plate XXVII.)
^P. urceolata.^ Frond three to ten inches high; main stem
bristle-like; branches naked below, divided and subdivided above;
branches with short branchlets set at a wide angle and often
recurved; siphons four in number; shows articulations; color deep
red. Name refers to cystocarp, which resembles a pitcher. The plant
grows in loose tufts, and is common from New York northward and on
the California coast.
Variety ^formosa^. Filaments soft and finer than in /P. urceolata/;
branches long and flexuous; articulations five to ten times longer
than broad; color bright red. It grows in tufts sometimes a foot
long, and is found only in the spring.
[Illustration: PLATE XXVII. Polysiphonia nigrescens. Polysiphonia
fibrillosa. Polysiphonia violacea. Polysiphonia Woodii.]
[Illustration: PLATE XXVIII. Laurencia pinnatifida. Dasya elegans.
Dasya plumosa. Dasya plumosa, magnified.]
^P. variegata.^ Fronds four to ten inches high; filaments thick as
a bristle below, and branched in a forking manner to the very top;
divided at long intervals below, at the top becoming of hair-like
fineness [pg089] and dividing rapidly, forming a densely
tufted mass, which collapses when taken from the water; color
purple-brown; when mounted, silky in appearance; filaments banded;
siphons six in number. It forms purple tufts on woodwork and on
eel-grass from Cape Cod southward.
^P. Woodii.^ Fronds four to six inches high; branches flat, long,
wide-spreading, emanating from the edges in one plane; younger
branches show articulations; ultimate branchlets inclined to curve
inward; color light brown. Found on the California coast. (Plate
XXVII.)
GENUS ^Laurencia^
^L. pinnatifida.^ Frond flat, thick, leathery; main stem with
opposite, or alternate, branches of about the same size and
character as itself; all pinnatifid, or cut on the edges into
branchlets, some of which are again divided; color bright purple,
often unevenly faded. It is found on the Pacific coast. (Plate
XXVIII.)
GENUS ^Dasya^
Chenille-weed.
^D. elegans.^ Fronds from six inches to three yards long; main stem
and branches cylindrical, and all densely clothed with a fine,
hair-like fringe, which gives the plant the appearance of chenille;
cystocarps on stalks along the branches; color pink or lake-red.
Out of water it seems like a mass of purple jelly. It is found at
or just below low-water mark from Cape Cod southward, and is very
plentiful in New York Bay. (Plate XXVIII.)
^D. plumosa.^ A species found on the California coast. The fringe
covering the stems consists of minute leaflets instead of hairs, as
in /D. elegans/. (Plate XXVIII.)
GENUS ^Bostrychia^
^B. rivularis.^ Fronds one inch high; color dark purple; branches
fine and irregularly bent. It grows where the water is not very
salt, and is found in patches on submerged logs near New York.
Common from Charleston, South Carolina, southward. (Plate XXIX.)
GENUS ^Rhodomela^
^R. subfusca.^ Frond six to eighteen inches long; main stem
cylindrical, and branching widely on all sides; branches longest
at base and gradually shortening to the top of the stem; branches
naked below, but at the ends profusely branched, forming tufts of
branchlets. It is a perennial plant, and changes in aspect with
the season. When mature it is stiff and coarse, and when dry it is
quite black. Common from New York northward.
^R. Rochei.^ This species resembles in form /R. subfusca/, but
is much finer and more delicate. In spring it is a soft, fine,
feathery, and beautiful [pg090] alga of a red-brown color. It
is found washed ashore, or in deep tide-pools, south of Cape Cod.
(Plate XXIX.)
^R. larix.^ Frond cylindrical, robust, six to fourteen inches high;
branches of unequal length standing out horizontally all around the
main stem; clusters of branchlets growing spirally around stem and
branches. Found on the northern California coast. (Plate XXIX.)
^R. floccosa.^ Frond four to ten inches high; less robust than /R.
larix/; stem and branches flat and divided in one plane; branches
alternate; ultimate branchlets somewhat incurved; color black. In
fertile plants the terminal branchlets are gathered in a mass.
Found on the California coast. (Plate XXIX.)
GENUS ^Chondria^
Plants of this genus are distinguished by having the ultimate
branches attenuated at the base.
^C. dasyphylla.^ Frond four to eight inches high; general outline
pyramidal; branches alternate on main stem; stem and branches
covered with short, club-shaped (blunt at top, attenuated at base)
branchlets; cystocarps, or spore-cases, adherent to branchlets or
on short stalks; color light or dull brown. It grows in tufts, and
is common from New York to Cape Cod. (Plate XXX.)
^C. tenuissima.^ This species is similar to /C. dasyphylla/, but
is more slender, and the branchlets taper at both ends instead of
being club-shaped.
^C. striolata.^ A species similar to /C. tenuissima/. The
branchlets bear secondary branchlets, and the cystocarps are on
short stalks. It is plentiful in Long Island Sound.
SUBORDER ~CERAMIEÆ~
GENUS ^Callithamnion^
These are very beautiful and delicate plants, growing in small,
soft, silky tufts, bright red in color, with darker dots along the
much-branched filaments. There are many species, and they are common
on the northern shores of both oceans; but the different species are
not easy to distinguish with the naked eye, and so but a few of them
are described below. The special characteristics by which the genus
may be recognized are: fronds filamentous, of cobweb fineness, one
inch to six inches long, much branched, and closely crowded at the
top; brilliant red color.
[Illustration: PLATE XXIX. Bostrychia rivularis. Rhodomela Rochei.
Rhodomela larix. Rhodomela floccosa.]
[Illustration: PLATE XXX. Chondria dasyphylla. Callithamnion
americanum. Callithamnion Pylaisæi. Callithamnion Pylaisæi, a piece
magnified.]
^C. americanum.^ Frond three to six inches long, densely tufted;
filaments of extreme fineness; main branches alternate; much
branched; main and secondary branches have pairs of branched
ramuli along the [pg091] branches; color rose-pink. It grows
on wharves and on algæ below low-water mark, and is a common and
beautiful species. It is found (but only in the spring) from New
York northward, and is abundant in Long Island Sound. (Plates XXX,
XXXI.)
^C. Pylaisœi.^ Fronds three to six inches long, more robust
and darker in color than in /C. Americanum/; main and secondary
branches alternate, decompound, all bearing at short intervals
short opposite branchlets, which in turn are covered with ramuli.
It is found in spring on wharves and on algæ from Boston northward.
(Plate XXX.)
^C. Baileyi.^ Fronds one inch to three inches long, with main
stem as thick as a bristle, and running to the top of the frond;
branches around the main stem longer at the base than at the
apex, giving the plant a pyramidal outline; branches also have a
main stem and short branches beset with branchlets; shrub-like in
aspect; color purplish-red. Common in summer from New York to Cape
Cod.
^C. seirospermum.^ Frond two to five inches high, pyramidal in
outline; has main stem and alternate lateral branches; branches
have secondary branches beset with delicate, erect branchlets;
hair-like in fineness. It is common from Cape Cod southward, and is
plentiful in Long Island Sound. (Plate XXXI.)
^C. byssoideum.^ Fronds one inch to three inches long; filaments
very delicate; main branches many times divided; secondary branches
long; many branchlets; rose-colored. It grows in globose tufts, and
is common in Long Island Sound. (Plate XXXI.)
^C. floccosum.^ Fronds three to six inches long, hair-like in
fineness; flaccid; main branches sparingly branched below;
numerous alternate branches above; all clothed with short, simple
branchlets; color dark brownish-red. The plant is so exceedingly
fine that it is difficult to distinguish the divisions. It grows on
eel-grass and on algæ below low-water mark, and is found from New
York to Cape Cod. (Plate XXXI.)
GENUS ^Griffithsia^
(/Named for Mrs. Griffiths, an English algologist/)
These are among the most beautiful of seaweeds, because of their
brilliant color and exceedingly delicate structure. They grow in deep
water, and specimens cast ashore are usually torn and imperfect, but
they may often be gathered from deep tide-pools, and sometimes are
found growing on eel-grass. If placed in fresh water they discharge
their coloring-matter and quickly decompose.
^G. Bornetiana.^ Fronds two to five inches high; filaments jointed,
the divisions being long and pear-shaped, growing shorter as they
near the top; repeatedly forked; very soft and fragile. It grows
in tufts, resembling corals; attains perfection in July, and
disappears later in the summer. Found from Cape Cod southward,
washed ashore after storms. (Plate XXXII.) [pg092]
GENUS ^Ptilota^
Feather-weed.
^P. serrata.^ Fronds three to six inches long, dark red in color,
cartilaginous; flattened main stem with opposite, flattened
branches, one of which is minute, so that it appears like alternate
branching; branches also have lateral branchlets and pinnulæ,
looking like feathers or ferns; all branching in one plane, making
a flat frond. It is found in the drift on the beach after a storm,
and is common from Cape Cod northward, and also on the California
coast. (Plate XXXII.)
^P. elegans.^ Narrower and more delicate than /P. serrata/,
otherwise it has the same essential features. It is common in
summer from New York northward, growing on cliffs, under /Fucus/,
near low-water mark, and it is also found washed upon the beach.
(Plate XXXII.)
^P. densa.^ Frond three to twelve inches high, one eighth of
an inch wide, flat, cartilaginous; has leading stem with flat
alternate branches; branches simple or branched again; edges of
whole plant beset with notched, curved pinnulæ alternating with
smaller feather-like pinnulæ, giving a dense edge to all parts of
the frond. It is found on the California coast. (Plate XXXIII.)
^P. hypnoides.^ Flat, cartilaginous main stem, much branched, and
all beset with pinnulæ. It differs from /P. densa/ in having the
alternate pinnulæ straight and club-shaped, instead of toothed and
curved, and the plant is not so dense and compact. Found on the
California coast. (Plate XXXIII.)
GENUS ^Spyridia^
^S. filamentosa.^ Fronds four to eight inches long; filaments as
thick as bristles, irregularly and repeatedly branched; young
branches show articulations and seem to be striped; all branches
clothed with short, very delicate, transparent filaments, which
give the plant a hazy appearance; color purplish-red, which becomes
brown when dried; does not collapse when taken from the water. It
grows in tufts below low-water mark, and is found in the drift on
the beach from Cape Cod southward. (Plate XXXIII.)
GENUS ^Ceramium^
The pitcher-weed. This genus is easily recognized by the ends of the
filaments, which are forked and incurved, resembling minute pincers
or claws. The filaments are also more or less distinctly banded. It
is widely distributed.
[Illustration: PLATE XXXI. Callithamnion americanum, a piece
magnified. Callithamnion seirospermum. Callithamnion byssoideum, var.
fastigiatum. Callithamnion floccosum.]
[Illustration: PLATE XXXII. Griffithsia Bornetiana. Ptilota serrata.
Ptilota serrata, magnified. Ptilota elegans.]
[Illustration: PLATE XXXIII. Ptilota densa. Ptilota hypnoides.
Ptilota hypnoides, magnified. Spyridia filamentosa.]
^C. rubrum^, red ceramium. This is a very common and robust
species, found everywhere, and growing on everything. It is
variable in appearance, becoming quite coarse when old, the
incurving, claw-like ends, which are characteristic of the genus,
being less pronounced. It branches by repeated forking, and, under
the microscope, shows a bark-like [pg093] layer of cells over
the whole surface, which make the ring-like bands on the filaments
less conspicuous.
[Illustration: PLATE XXXIV. Ceramium rubrum, var. proliferum.
Ceramium rubrum, top of frond magnified. Ceramium diaphanum.
Ceramium tenuissimum, var. patentissimum.]
Variety ^proliferum^. Fronds beset on all sides with simple or
forked branchlets. (Plate XXXIV.)
Variety ^secundatum^. Branchlets generally arranged on one side of
the filaments, or secund.
^C. strictum^ ("straight"). Brown or purplish-red filaments of
hair-like fineness, growing in tufts two to six inches high,
branching in narrow forks more and more closely as they reach the
top of the frond. There are no principal branches, the filaments
being of about the same diameter and regularly dividing in a
forking manner throughout. The filaments are banded, the red rings
being relatively very narrow. The white interstices at the base are
several times longer than broad, but shorten gradually until at the
top they are of equal length with the red bands. This species is
common from Cape Cod to New York.
^C. diaphanum.^ This species has comparatively stout leading
branches, with secondary alternate branches which are finer than
the main stems and divide in a forking manner throughout, and
ultimately become very fine. The color is brown or purplish-red,
distinctly banded. It grows on eel-grass and algæ, and is found
from Cape Cod to New York. (Plate XXXIV.)
^C. fastigiatum.^ Filaments of hair-like fineness and of about same
size throughout; branched in regular forking manner throughout,
the divisions being wide and distant at the base, but gradually
becoming closer and narrower as they reach the top; the upper
segments about equal, giving a level top and regular outline in
mounted specimens; the terminal forks erect, or less incurved than
in other species; small points or branchlets emanate from some of
the nodes or joints between the bands of color; tufts globe-shaped,
two to five inches high; color lake-red. This species grows on
mud-flats and mud-covered rocks as well as on algæ and eel-grass.
^C. tenuissimum.^ Fronds two to four inches high, densely tufted;
the forked divisions very wide or open; color rose-pink.
Variety ^patentissimum^. Fronds small; the forked divisions distant
and very wide open. A mounted specimen appears somewhat like
network. The species is common in Long Island Sound. (Plate XXXIV.)
GENUS ^Microcladia^
^M. Coulteri.^ Cylindrical, slightly flattened main stem; branches
set uniformly and alternately, short at the base, gradually
lengthening as far as the center, and from there diminishing to
the apex of the stem, giving a leaf-like outline. The same mode
of branching and the same outline are repeated in the branches.
The ultimate divisions are like forked divisions, and are somewhat
incurved. The plant is six to eight inches high, and in color is
of many shades of red and pink. It is found in abundance on the
Pacific coast at all seasons. (Plate XXXV.)
^M. borealis.^ Branches and branchlets placed on one side of arched
main stems; secondary branches curved in opposite direction and
bearing branchlets, also divided on one side only; color dark
brown. It is found on the northern Pacific coast. (Plate XXXV.)
[pg094]
ORDER =CRYPTONEMIACEÆ=
SUBORDER ~GLOIOSIPHONIEÆ~
GENUS ^Gloiosiphonia^
("/Viscid tube/")
^G. capillaris.^ Frond six to ten inches high, solitary or in
tufts; main stem cylindrical, solid above, hollow below; from about
an inch above the base densely beset with short, wide-spreading
branches arranged evenly and all around the stem; branches again
branched in the same way; branches and branchlets attenuated at
base and apex; soft, tender, juicy; shrinks much in drying. The
species is easily recognized by its delicate gelatinous substance,
tapering branchlets, and brilliant red color. It is found in early
summer in tide-pools on the New England coast.
SUBORDER ~GRATELOUPIEÆ~
GENUS ^Halymenia^
^H. ligulata.^ Frond membranaceous, repeatedly and regularly
divided in a forking manner; the larger divisions one half of an
inch wide and growing very narrow at the top; four to five inches
high, spreading in a fan-shape; color rose-red. It is found at Key
West.
GENUS ^Grateloupia^
^G. Cutleria.^ Frond coarse, flat, variable; either simple,
long, and narrow, or short and broad, tapering at both ends, or
blunt at the apex, or deeply cleft into many segments; sometimes
with leaflets along the edges; height two to three feet; color
reddish-brown; in fading, changes to purple and green, and may be
variegated. When simple, the plant resembles /Iridæa/. Found on the
northern California coast.
GENUS ^Prionitis^
^P. lanceolata.^ Frond narrow, flat, smooth; leathery stems, which
branch irregularly and sparingly from the edges; branches bordered
with lance-shaped leaflets; color dark brownish-red; plant ten or
more inches high, and varies considerably. (Plate XXXV.)
There are other species, among them ^P. Andersonii^ (Plate XXXVI.);
all are easily distinguished by the lance-shaped leaflets. Common
on the Pacific coast.
[Illustration: PLATE XXXV. Microcladia Coulteri. Microcladia
Coulteri, magnified. Microcladia borealis. Prionitis lanceolata.]
[Illustration: PLATE XXXVI. Prionitis Andersonii. Pikea Californica.
Halosaccion ramentaceum. Polyides rotundus.]
SUBORDER ~DUMONTIEÆ~
GENUS ^Pikea^
^P. Californica.^ Divisions of frond thick, narrow, cartilaginous;
central axis one eighth of an inch to one inch wide, three to four
inches high, thickly set with similar branches irregularly placed;
all bordered [pg095] with numerous forward-pointing branchlets,
which in turn have spine-like ramuli of various lengths; frond
flat, broadly spreading; dark red. It is common at all seasons on
the California coast. (Plate XXXVI.)
GENUS ^Halosaccion^
^H. ramentaceum.^ Fronds brownish-purple, six to fourteen inches
long, coarse and cartilaginous, cylindrical, hollow, compressed,
attenuated at the base; more or less covered with simple or forked
hollow branches half the size of the main stem. In exposed pools
the plants are short and densely branched; in sheltered places they
are larger and more delicate in texture. They are common on the
northern New England and northern California coasts. (Plate XXXVI.)
SUBORDER ~RHIZOPHYLLIDEÆ~
GENUS ^Polyides^
^P. rotundus.^ Frond three to six inches high, cylindrical,
cartilaginous, repeatedly forked, ends obtuse; spore-masses form
numerous lighter-colored excrescences on the upper divisions of the
frond; dark red. Common from New York northward, in deep pools and
washed ashore. (Plate XXXVI.)
SUBORDER ~SQUAMARIEÆ~
GENUS ^Peyssonnelia^
^P. Dubyi.^ Frond completely adherent to the rock or stone on
which it grows; color dark purple; somewhat calcareous; redder and
thicker than next species. It is found at low-water mark or in deep
water on the northern New England and northern California coasts.
GENUS ^Petrocelis^
^P. cruenta.^ Frond closely adherent, forming dark-purple velvety
patches of indefinite outline on rocks and stones. Common north of
Cape Cod.
GENUS ^Hildenbrandtia^
^H. rosea.^ Forms continuous pink incrustations of considerable
extent on stones and rocks at low-water mark. Common everywhere.
SUBORDER ~CORALLINEÆ~
The genera of this suborder are characterized by a calcareous or
stony incrustation of the fronds, which gives them the appearance of
corals. Most of the species are tropical. [pg096]
GENUS ^Corallina^
("/Coral-like/")
^C. officinalis^, common coralline. Frond grows from a disk in
tufts more or less dense. The plant is rigid, and seems like
jointed, branched coral. The articulations are cylindrical at the
base, wedge-shaped and flattened above. Branches emanate from the
top of the articulations. The color varies from reddish-purple to
gray-green, and is often bleached white when exposed to the sun.
Common in tide-pools and on rocks at low-water mark from New York
northward. (Plate XXXVII.)
GENUS ^Melobesia^
This genus will attract attention, although it cannot be gathered. It
is a thin, brittle, scaly substance of indefinite form, which expands
horizontally and resembles a lichen. It forms brown and pink crusts
on other algæ and on rocks, stones, and shells.
ORDER =BANGIACEÆ=
GENUS ^Bangia^
^B. fusco-purpurea^ ("brown-purple"). Fine, hair-like, unbranched,
dark-purple filaments, one inch to six inches long. It grows in
large patches on rocks and woodwork, floating free, but falling
into soft, silky, fleece-like masses when left by the tide. Common
on northern shores. (Plate XXXVII.)
GENUS ^Porphyra^
("/Purple dye/")
This plant, except in color, is like the green alga /Ulva/. In
color it is purple of various shades. The species are named from
variations in the outline of the frond. They are found everywhere,
and throughout the year. The plants are edible, being the laver of
commerce, eaten principally by the Chinese, who make them into soup.
^P. vulgaris.^ Frond a broad, thin membrane of purple color, three
to twelve inches across; margin much waved; sometimes attached at
the center, often widely expanded and folded, sometimes deeply
lobed. (Plate XXXVII.)
^P. laciniata.^ Differs from /P. vulgaris/ in being divided into
narrow segments or into wavy, ribbon-like forms. (Plate XXXVII.)
[Illustration: PLATE XXXVII. Corallina officinalis. Bangia
fusco-purpurea. Porphyra vulgaris. Porphyra laciniata.]
PART II
MARINE INVERTEBRATES
I
PORIFERA
(SPONGES)
TABLE SHOWING THE CLASSIFICATION OF THE SPONGES DESCRIBED IN THIS
CHAPTER
Phylum and Class =PORIFERA=
Subclass =Calcarea=
Order =HETEROCŒLA=
Family ~SYCONIDÆ~
Genera Species
^Grantia^ ^G. ciliata^
^Leucosolenia^ ^L. botryoides^
Subclass =Non-Calcarea=
Order =CHONDROSPONGIÆ=
Family ~SUBERITIDÆ~
^Suberites^ ^S. compacta^
^Polymastia^ ^P. robusta^
^Cliona^ ^C. sulphurea^
Order =CORNACUSPONGIÆ=
Family ~DESMACIDONIDÆ~
^Esperiopsis^ ^E. quatsinoensis^
^Microciona^ ^M. prolifera^
Family ~HETERORRHAPHIDÆ~
^Tedania^
Family ~HOMORRHAPHIDÆ~
Genera Species
^Halichondria^ ^H. panicea^
Family ~SPONGIDÆ~ Subfamily ~EUSPONGINÆ~
^Chalinopsilla^ ^C. oculata^
^C. arbuscula^
^Euspongia^ ^E. officinalis^
Var. ^adriatica^
Var. ^mollissima^
Var. ^rotunda^
Var. ^dura^
^Hippospongia^ ^H. equina^
Var. ^cerebriformis^
Var. ^meandriformis^
Var. ^elastica^
^H. canaliculata^
Var. ^gossypina^
Var. ^flabellum^
Family ~SPONGIDÆ~ Subfamily ~STELOSPONGINÆ~
^Hircinia^ ^H. campana^
[pg101]
SPONGES
There are many animals which consist of but one cell. These are
called /Protozoa/, and comprise the /Infusoria/ and other microscopic
organisms. The animals next higher in the scale are /Metazoa/, or
multicellular animals, and the first group of this subdivision is
=Porifera=, the sponges, the lowest of the many-celled animals.
For a long time sponges occupied a disputed ground between the animal
and vegetable kingdoms. Aristotle was the first to point out that a
sponge is not a plant. The assertion was doubted and combated, but at
last the animal nature of the sponge was established. Sponges were
then believed to be colonies of one-celled animals, but finally it
was decided that they were individuals with cells of different kinds
that performed functions analogous to those of higher organisms.
The sponge, as commonly seen, is only the skeleton or framework, so
to speak, of the living animal. In its natural state it is a very
different-looking object. Its entire surface is covered with a thin
slimy skin, usually of a dark color, which is perforated with holes
corresponding to the apertures of the canals. The organic portion
of the sponge is a soft, jelly-like substance composed of three
layers—the external (/ectoderm/), the internal (/endoderm/), and
the middle (/mesoderm/). The external layer is composed of flat
cells. The endoderm has cylindrical cells, each one of which has a
flagellate hair. The main mass of the body, the mesoderm or middle
layer, is made up of cells having various functions, some being
concerned in the formation of framework, some in digestion, and some
in reproduction.
The framework is secreted in the mesoderm, and in different
[pg102] genera consists respectively of a horny or silicious or
calcareous substance, or of the first two of these substances
combined. The sponge of commerce has the first kind and is composed
entirely of exceedingly fine flexible fibers of a horny substance
called /spongin/. In other species the spongin is intermixed with
spicules of silica, or of carbonate of lime, in various shapes.
In the sponges, so much valued as curiosities, called "Venus's
flower-basket" and "glass-rope sponge," the framework is composed of
silicious spicules alone.
[Illustration: Various forms of sponge-spicules.]
The spicules have a great variety of shapes, being rod-like, knobbed,
three-pointed, six-pointed, anchor-like, etc., and are a feature in
the classification of sponges.
[Illustration: To illustrate choanocytes (/Ch/): section of a
calcareous sponge. /Ect/, ectoderm; /Mes/, mesoderm; /N/, calcareous
spicule; /Eiz/, ovum.]
The sponge is traversed throughout by a canal system, consisting of a
series of tubes through which water circulates, carrying air and food
to the animal. The exterior of the sponge has numerous small pores
and a comparatively few large openings. The fine pores are inhalent,
taking in and straining the water of its coarser floating material,
and then passing it through perforations in their sides into sacs
lined with peculiar cylindrical cells having flagellate hairs, each
hair having a collar at its base. These cells, called /choanocytes/,
resemble independent animals of the /Protozoa/, known as /flagellate
Infusoria/ or /Choanoflagellata/. [pg103] They take in and digest
food and eject excrement from the area inclosed by the collar. The
cilia (hairs) by their constant movement create currents which keep
the water in motion. Water, then, is taken through the pores into
the first or incurrent canals; thence it is passed into the ciliated
chambers, and thence into the excurrent canals, and out through large
passages terminating in large openings called /oscula/, or craters.
The canal systems vary. In some species they become quite complex.
[Illustration: Canal system of /Sycon gelatinosum/. Transverse
section through the wall of a cylinder (parallel with the course of
the canals), showing one incurrent canal (/IC/) and one radial (/R/)
throughout their length; /sp/, triradiate spicules; /sp´/, oxeate
spicules of dermal cortex (/dc/); /sp´´/, tetraradiate spicules
of gastral cortex (/gc/); /ec/, ectoderm; /en/, endoderm; /pm/,
pore-membrane; /pp/, prosopyle; /ap/, apopyle; /di/, diaphragm;
/exc/, excurrent passage; /PG/, paragastric cavity; /em/, early
embryo; /em´/, late embryo. (The arrows indicate the course of the
water through the sponge.)]
Sponges vary greatly in shape, size, color, surface, rigidity,
canal systems, and skeleton. They are cake-shaped, tubular,
digitate, palmate, cup-shaped, vase-shaped, cone-shaped, spherical,
hemispherical, pedunculate, etc., their shapes depending upon whether
their growth is uniform or is excessive in a horizontal or in a
vertical direction. When they grow evenly in both directions massive
uniform shapes arise. If lateral growth predominates, broad, low,
and incrusting shapes result. When there is an excess of vertical
growth the forms are digitate; [pg104] but if vertical growth is not
greatly in excess and is restricted to the marginal part, cup-shaped
forms result, and tubular forms when lateral growth is particularly
restricted. In some varieties tubular masses coalesce; sometimes flat
forms unite in intricate compressed folds. Differences in rapidity of
vertical growth make undulations more or less marked, producing lobes
and protuberances. Sometimes narrow vertical growth is retarded and
horizontal growth predominates, forming various shapes on apparent
stems.
Many of the horny sponges are colored, in shades of yellow, brown,
red, and violet; some are black.
Sponges are divided into two classes, the =Calcarea= and
=Non-Calcarea=. The former have calcareous skeletons, which make them
hard and rigid; the latter have skeletons of spongin-fiber or of
silicious spicules, or of the two combined.
All sponges, with the exception of one family (the /Spongillidæ/,
which live in fresh water), are inhabitants of the sea, and live at
various depths. The sponges of commerce belong to the /Non-Calcarea/
and are all confined to the genus /Spongia/. In this genus the
skeleton is more or less flexible, being composed of spongin. They
are shallow-water species, are confined to seas where the waters are
of comparatively uniform high temperature, and flourish best when
protected by reefs and islands.
There are fisheries for sponges in the waters of the West Indies, the
Bahamas, on the southern and western coasts of Florida, and in the
Mediterranean and Red seas. Those of the Mediterranean surpass in
quality the sponges of our coasts.
Five species of commercial sponges are taken from Florida waters.
They are graded by the trade in the order of their importance, as the
"sheepswool," "yellow," "grass," "velvet," and "glove." The fishing
for sponges is done from small boats, two persons manning each boat.
One man sculls, while the other, using a water-glass, scans the
bottom. The water-glass is a box with a pane of glass on the bottom.
If the glass is held below the surface and the face is placed in
the box, the observer is enabled to see with some distinctness the
bottom at a considerable depth [pg105] in these clear waters. The
sponges are dragged up by hooks—a primitive method which restricts
the fishing to shallow water, the fishing here being in water not
deeper than thirty feet, but usually three to twenty feet. The
sponges are "killed" by being exposed on the beach for several days;
they are then placed in "crawls," or pens, where they are washed by
the action of the waves for about a week; then, if clean, they are
dried, assorted, strung on cords, pressed and baled for shipment. The
sponge-fisheries are of considerable value, and much attention is
being given to the subject of artificial propagation. It is thought
that such beds could be subjected to the regulations which govern
oyster-beds. Already the planting of sponges has been shown to be
practicable. The living sponge is cut to pieces, and the cuttings
are placed in favorable localities. Pieces planted in Florida waters
attain a marketable size in one year.
Sponges reproduce by eggs formed in the mesoderm. The eggs escape as
ciliated spheres and swim about until they find a place on which to
attach themselves. As soon as they become fixed they grow with much
rapidity into mature individuals.
Some species seem to prefer association with other animals and live
as commensals with crabs. The crab /Dromia/ is always concealed under
a sponge, which grows upon its back. Spider-crabs are often overgrown
with sponges as well as seaweeds. In this case, however, the crab
finds and plants the sponge himself. /Aplysella violacea/ overgrows
worm-tubes. Many sponges afford shelter to numerous small animals
which bore into their bodies for protection, no animal seeming to
feed upon the sponge.
Sponges may be found in tide-pools, on the under side of stones,
on seaweeds, and so on. A small bright-red incrusting sponge with
irregular lobe-like branches is common on the New England coast; a
thin yellow incrusting sponge also is found on the under side of
stones. /Grantia ciliata/, a small urn-shaped species, having a large
aperture at the summit, is found in tide-pools.
Perhaps the most singular in habit of any sponge is /Cliona
sulphurea/, the boring-sponge, a common species found from Cape
Cod to South Carolina and abundant in Long Island Sound. It
[pg106] is bright sulphur-yellow in color, grows in irregular
masses of considerable size and fine texture, and has low wart-like
prominences. It lives on shells spreading over both surfaces, at
first forming little burrows, but eventually penetrating the shell in
every direction, honeycombing and at last completely destroying it
by absorption. Sometimes it settles upon living shells and greatly
irritates the animal, which constantly secretes new lime to cover the
perforations in its shell.
These sponges are an important factor in the economy of the sea, as
they disintegrate dead shells, which would otherwise accumulate in
vast quantities.
SUBCLASS =CALCAREA=
GENUS ^Grantia^
^G. ciliata.^ Small, urn-shaped or oval, with large aperture at the
summit, surrounded by a circle of projecting spicules. It is found
in tide-pools and on piles of wharves from Rhode Island northward.
GENUS ^Leucosolenia^
^L. botryoides.^ Tubular, branched. Occurs in the same places as
/Grantia ciliata/.
SUBCLASS =NON-CALCAREA=
GENUS ^Suberites^
^S. compacta.^ Elongated, compressed masses, sometimes in several
lobes; attached by one edge; texture fine, firm, compact; surface
smooth; color bright yellow. It grows on sandy bottoms, and is
common in shallow water south of Cape Cod. (Plate XXXVIII.)
GENUS ^Polymastia^
^P. robusta.^ When young it forms yellowish-white incrustations
over shells and stones; later it grows into long, slender, round,
tapering, finger-like projections. Found on the northern New
England coasts in deep water.
GENUS ^Cliona^
^C. sulphurea^, the boring-sponge. Irregular massive form of firm
texture; surface covered with scattered low wart-like prominences
about one eighth of an inch in diameter; bright sulphur-yellow. It
destroys, by absorption, vast quantities of dead shells.
[Illustration: PLATE XXXVIII. Halichondria panicea. Suberites
compacta. Hircinia campana. Esperiopsis quatsinoensis (found on the
sea-beaches of Alaska).]
[Illustration: PLATE XXXIX. Microciona prolifera. Chalinopsilla
arbuscula. Chalinopsilla imitans. Euspongia officinalis, var. tuba.
Chalinopsilla oculata.]
GENUS ^Microciona^
^M. prolifera.^ When young this species forms bright-red
incrustations over shells and stones; later it rises into irregular
lobes and tubular prominences. When fully developed it is profusely
branched in a forking manner. The branches are more or less
flattened, and often are palmate at the ends. It grows in clusters
six inches in diameter, of a dark orange-red color. When dry it is
grayish-brown, brittle, and bristly. It is found from Cape Cod to
South Carolina, and is abundant in Long Island Sound. (Plate XXXIX.)
GENUS ^Tedania^
Irregular, uneven, pale-yellow masses spreading over seaweeds; oscula
scattered irregularly over the surface; texture close.
GENUS ^Halichondria^
^H. panicea^, crumb-of-bread sponge. It resembles the crumb of
bread, and is found cast up on all beaches. (Plate XXXVIII.)
GENUS ^Chalinopsilla^
^C. oculata^, the finger-sponge. Stem stout, more or less
flattened, dividing at the upper end into branches which vary in
form and thickness, being finger-like or more or less compressed
lobes; oscula scattered over the smooth, undulating surface;
texture rather hard, but delicate; color, when living, dull
orange-red; when the animal matter is removed, white. The species
is found in shallow and deep water from New York to Labrador.
Common in Massachusetts Bay. (Plate XXXIX.)
^C. arbuscula.^ Profusely branched in a forking manner from close
to the base; branches slender; clusters six to eight inches high
and about the same in breadth; color buff or gray when living,
yellowish-white when free from animal matter; texture finer and
more delicate than that of /C. oculata/. It is found in shallow
water from Cape Cod to North Carolina, and is abundant in Long
Island Sound. (Plate XXXIX.)
GENUS ^Euspongia^
^E. officinalis.^ This is one of the commercial sponges and is
known as the "glove-sponge." It is the one of least marketable
value, having inferior elasticity and becoming brittle with
age; yet a Mediterranean sponge of the same species, variety
/adriatica/, is of the finest quality and greatest value. This
singular fact demonstrates that the quality of sponges depends
largely upon physical conditions. /E. officinalis/ has an average
height of five to six inches. It grows on rocky bottoms in shallow
water on the east coast of Florida. This species has a number of
varieties of various forms; some are dome-shaped, others tubular,
rotund, flabellate, etc. The surface is covered with fine tufts
and is generally free from ridges. On the sides are numerous small
apertures, [pg108] and one or more large oscula occur on top. The
color of the living sponge is black. (Plates XXXIX, XL.)
^E. officinalis^, variety ^adriatica^. More or less globose;
sometimes attached by a broad base, sometimes by a short stem;
latter form more or less club-shaped; oscula scattered over upper
surface. Found in the West Indies and the Mediterranean. (Plate XL.)
^E. officinalis^, variety ^mollissima^, the Levant toilet-sponge.
Generally cup-shaped; oscula on inner side of cup or on upper flat
surface; very soft and elastic.
^E. officinalis^, variety ^rotunda^. Usually massive; attached by a
broad base; sides vertical; oscula large and conspicuous on top, or
small in longitudinal rows on the sides. In the young this variety
may have a conical form with only one orifice, but later it has
several oscula. Its rotundity of form increases with the number of
large orifices, but in the adult stages the form varies, some being
conical, while others have the top divided into radiating ridges.
^E. officinalis^, variety ^dura^. Irregular, massive, horizontally
expanded, with conical process on upper surface.
GENUS ^Hippospongia^
^H. equina.^ Some of the sponges of this species are massive,
spherical, and attached by a small base; others are horizontally
expanded or cake-shaped; some have a depression in the upper
surface and become cup-shaped.
^H. equina^, variety ^cerebriformis^. Massive, circular,
cake-shaped, often depressed in the center, producing a cup-shape,
attached by broad base; surface broken up by parallel longitudinal
ridges having many tufts. Cup-shaped forms predominate, and have
a more or less rough surface. This is one of the species known as
grass-sponges.
^H. equina^, variety ^meandriformis^, the velvet sponge. The
surface of this variety has a protruding flattened cushion of fiber
which slightly resembles the convolutions of the brain-coral.
Sometimes these cushions are extended into long pencils. The oscula
are large and ragged on the edges; the shape is irregular. The
average size is seven to eight inches in diameter. (Plate XL.)
^H. equina^, variety ^elastica^ (variety ^agaricina^, Hyatt), the
yellow sponge. This is the second grade of commercial sponge,
corresponding to the Zimocca sponge of the Mediterranean. It is
found growing with the "sheepswool" in a depth of two to twenty
feet, and is abundant. It is massive and cake-shaped. The whole
surface is a network covered with numerous small, fine cones.
(Plate XL.)
The variety ^dura^ is classed with this species, which it resembles
in appearance, though it is harder in texture.
^H. canaliculata.^ Massive, frondose; more or less horizontally
expanded; bears finger-like processes of varying development on the
upper surface.
^H. canaliculata^, variety ^gossypina^, the sheepswool sponge. This
is the highest grade of the commercial bath-sponge. It is called
"sheepswool" because, perhaps, of its irregular shaggy surface. It
is covered with tufts, the larger oscula occupying the intervening
depressions.
[Illustration: PLATE XL. Euspongia officinalis, var. adriatica.
Hippospongia equina, var. meandriformis. Hippospongia canaliculata,
var. gossypina. Hippospongia equina, var. elastica. Euspongia
officinalis.]
Sometimes these are very numerous, the whole interior being
cavernous; again, the structure is more dense, with fewer large
openings and more of the small ones between the tufts; again, the
depressions are filled up so that the surface has fewer tufts.
When living, the color is shining black. This is the best sponge
found on the American coast, and although of coarser texture than
the best Mediterranean sponges, it is more durable and quite as
elastic. (Plate XL.)
^H. canaliculata^, variety ^flabellum^ (^Spongia graminea^, Hyatt).
This is one of the species of sponges of the third commercial
grade, which bear the trade-name of "grass-sponge." The shape is
cone-like, with either a flat or a funnel-shaped top. The oscula
are on the upper surface. The sides are fluted with deep furrows
which contain the small incurrent apertures.
GENUS ^Hircinia^
^H. campana.^ The normal variety is vase-shaped, but the species
varies greatly in form. Some varieties have branches. When living,
its color is black. It is found at Key West in four to forty feet
depth. (Plate XXXVIII.)
II
CŒLENTERATA
(POLYPS)
Phylum
=CŒLENTERATA=
Classes
=HYDROZOA=
(/Zoöphytes, small Jellyfishes, and a few Corals/)
=SCYPHOZOA=
(/Large Jellyfishes/)
=ACTINOZOA=
(/Sea-anemones and most of the Stony Corals/)
=CTENOPHORA=
(/Comb-jellies/)
CŒLENTERATA
The animals included in the phylum =Cœlenterata= were once all
called /zoöphytes/, or animal plants, because of their resemblance
to vegetable forms. The name /Cœlenterata/ is derived from two
Greek words meaning "hollow" and "intestine," and it describes the
anatomical structure of each member of the group. They are commonly
known as polyps. In the simplest forms the parts which perform the
different functions cannot be distinguished one from the other, and
even in higher forms there is but little differentiation. Shakspere's
description of old age applies to them: "Sans teeth, sans eyes, sans
taste, sans everything."
Nevertheless, this very low order of animals has, like the
higher orders, such a diversity of form and habit as to require
classification. Some of them are stationary, and of these some branch
like plants; some move about by the aid of tentacles, some move by
means of vibrating cilia, and others move by the contraction and
expansion of the soft body.
Cuvier included them in his /Radiata/, a class comprising all the
animals whose parts diverge or radiate from a central axis. Recent
classification has divided the radiate animals into several classes.
This arrangement of parts is obviously quite different from that
of bilateral symmetry, or the disposal of parts on each side of a
longitudinal axis. The type of radiate structure is shown in polyps.
The body is a sac, in the center of which is another sac or axis.
This is the digestive cavity. Vertical partitions extend from the
central to the outer sac, forming distinct [pg114] divisions or
chambers. The number of divisions varies with the different species
and also with the age of the animal. Other partitions start from the
outer sac, and extend toward the central axis, but do not unite with
it. These partitions, called /mesenteries/, are always in definite
multiples, varying in different species, new divisions growing
between the first partitions in regular order. On the inner edge
of these partitions the eggs of the animal are formed, which, when
mature, drop into the chambers and pass through openings into the
inner sac, or digestive cavity, and out of the mouth into the water.
[Illustration: Diagram of radiate structure.]
The animals are classed according as the eggs are formed on all
or on special partitions, those being of the highest order where
a limitation and constancy of function is maintained. The upper
surface of the body has hollow tentacles, each one of which opens
into one of the chambers and extends outward. All parts of the animal
communicate, and whatever enters the mouth circulates through the
whole structure; and when assimilation is completed the residue
returns by the same road and is expelled through the mouth. This
structure is common to all polyps; but there are great differences
in their texture, some being soft and some horny, while others
deposit a calcareous skeleton (corals). Some grow in colonies, like
the hydroids and corals, and are stationary, others are free and
independent; some have but few, others have many tentacles; and they
differ widely in size, form, and color.
Hydroids, sea-anemones, corals, sea-fans, starfishes, and sea-urchins
are different examples of the radiate structure. They are not,
however, all of them polyps.
The /Cœlenterata/ are divided into four classes: =Hydrozoa=, which
include the colonies of zoöphytes which resemble seaweeds, the small
jellyfishes which are born of these colonies, and the /millepores/,
which are colonies of zoöphytes which secrete a stony instead of a
horny skeleton, yet differ in some respects from other [pg115] stony
corals; =Scyphozoa=, large jellyfishes, many of which do not have the
double form of development; =Actinozoa=, the sea-anemones and the
different forms of stony corals, including sea-fans, sea-pens, etc.;
=Ctenophora=, the jellyfishes commonly known as comb-jellies. [pg116]
TABLE SHOWING THE CLASSIFICATION OF THE HYDROZOA DESCRIBED IN THIS
CHAPTER
Class =HYDROZOA=
Order =LEPTOLINIÆ= (/Branched colonies or shrub-like communities of
hydroids; some permanently fixed, others liberate swimming-bells/)
Suborder =ANTHOMEDUSÆ= (/Zoöids not covered by protective sheath;
umbrella of medusæ strongly arched; egg-sacs in manubrium/)
Division TUBULARIANS (/Without polyp-cups/)
Genera and Species
^Clava leptostyla^
^Hydractinia polyclina^
^Coryne mirabilis^
^Sarsia^
^Eudendrium ramosum^
^Tubularia indivisa^
^T. Couthouyi^
^Parypha crocea^
^Corymorpha pendula^
^Hybocodon prolifer^
^Pennaria tiarella^
^P. gibbosa^
^Bougainvillea superciliaris^
Suborder =LEPTOMEDUSÆ= (/Zoöids covered with cup-like sheaths;
umbrella of medusæ thin and not very convex; egg-sacs in line
of radial canals/)
Division CAMPANULARIANS (/Polyp-cups stalked/)
Genera and Species
^Obelia commissuralis^
^Eucope diaphana^
^Oceania languida^
^Clytia poterium^
^C. bicophora^
Division SERTULARIANS (/Polyp-cups sessile/)
^Sertularia pumila^
^S. argentea^
^S. cupressina^
Division PLUMULARIANS (/Polyp-cups on one side of branches
only/)
^Aglaophemia struthioides^
^Plumularia falcata^
Family =GERYONOPSIDÆ=
^Tima formosa^
Family =ÆQUOREIDÆ=
^Zygodactyla groenlandica^
Order =TRACHYLINÆ= (/No fixed zoöphyte stage; always
free-swimming medusæ/)
Suborder =TRACHYMEDUSÆ= (/Tentacles spring from margin of
umbrella; manubrium long; gonads in connection with radial
canals/)
Genera and Species
^Trachynema digitale^
Suborder =NARCOMEDUSÆ= (/Tentacles spring from midway between
summit and margin of umbrella; manubrium short; gonads in
connection with manubrium/)
Order =HYDROCORALLINA= (/Skeleton of carbonate of lime/)
^Millepora alcicornis^
Order =SIPHONOPHORA= (/Pelagic free-swimming colonies; exhibit
extreme polymorphism of zoöids/)
^Nanomia cara^
^Physalia arethusa^
^Vellela limbosa^
TERMS USED IN DESCRIBING HYDROIDS
^Cœnosarc^ ("common flesh"): The fleshy axis, or organized living
bond, by which the zoöids are organically united to one another. It
consists of three layers: ectoderm, endoderm, and mesoderm.
^Ectoderm^ ("outside skin"): The outside one of the three organized
layers of which every hydroid is composed.
^Endoderm^ ("inside skin"): The innermost layer.
^Gonangium^ ("seed-vessel"): The external horny receptacle within
which the gonophores are developed.
^Gonophore^ ("seed-bearing"): A generative zoöid.
^Hydranth^ ("water flower"): A nutritive zoöid.
^Hydrorhiza^ ("water-root"): The part of the colony which fixes it to
other bodies, like a root.
^Hydrosoma^ ("water-body"): The entire hydroid colony.
^Hydrotheca^ ("water-receptacle"): The cup-like, horny receptacle
which protects the hydranth.
^Mesoderm^ ("middle skin"): A layer which lies between the ectoderm
and the endoderm.
^Nematophore^ ("thread-bearing"): The name of peculiar bodies
developed in certain genera from definite points; characteristic of
plumularians.
^Perisarc^ ("around flesh"): The transparent, chitinous shell, or
unorganized outer membrane of horny consistency, which covers to a
greater or less extent the soft parts of the colony.
^Zoöid^ ("animal form"): One of the animals which form the colony.
[pg119]
CLASS =HYDROZOA=
SEAWEED-LIKE ZOÖPHYTES AND SMALL JELLYFISHES
The hydroids have been called the nurses of jellyfishes. From casual
observation these two forms would not be associated together, for the
shrub-like organisms, which so much resemble plants that they are
often collected and preserved as seaweeds, suggest only vegetable
life. Examined with a glass, however, they disclose their animal
nature. Along the stems, arranged in various ways, are small cups,
from which protrude the numerous moving tentacles of the little
polyps living within them.
/Hydroids are colonies of associated animals living a communal life./
The multitude of individuals composing the colony are invested with
a horny covering, the /perisarc/, which in some genera assumes a
tree-like form. Through these stems and branches runs a fleshy tube,
a thread of animal substance, which connects in one living whole
the zoöids, or individuals of the community. There is division of
labor, as in other communities: some of the zoöids obtain the food
for the colony, and have tentacles around their open mouths; others
have no mouths, but reproduce the species, and at certain stages of
development liberate swimming-bells, or small jellyfishes (medusæ).
The typical hydroid colony is attached by a kind of creeping stem
from which arises a vertical axis, which gives off short lateral,
alternate branches bearing zoöids at their ends. There is often more
complex branching. The zoöids in certain genera (tubularians) are
uncovered; in others (sertularians) they are incased in a glassy,
cup-like, horny sheath.
Three kinds of zoöids, polyps, or hydranths—as they are
indiscriminately called—are attached to the stem. Those having
an [pg120] open end and a crown of tentacles are the nutritive
individuals. Small, club-like dilations are immature zoöids. The
/blastostyles/, or reproductive zoöids, are long, cylindrical,
mouthless, and covered. At maturity the cover is ruptured, and the
medusæ have the appearance of a pile of thin saucers attached by the
middle of the convex side. When at length these saucers are set free
as little medusæ, or jellyfishes, the convex side of each saucer,
or swimming-bell, is called the /ex-umbrella/; the concave, under
side, the /subumbrella/. From the center of the subumbrella projects
the /manubrium/, or stomach of the animal. At the free end of the
manubrium is a four-cornered mouth. From the attached end of the
/manubrium/ four tubes or canals diverge, and, extending through the
animal, open into a circular canal which runs around the margin of
the umbrella. When the medusa is as above described, it has reached
the highest point in its development.
When the medusa has matured, it lays eggs, known as /planulæ/. These
are spherical bodies covered with cilia (hairs), by means of which
they swim about for a time; but they finally attach themselves
to some object, there to grow and develop into hydroid colonies.
The cycle of life is thus completed. This process is known as
/alternation of generation/, or /metagenesis/, one life-history
containing two quite different forms of being. The term of life of an
individual is one year, the zoöphyte stage beginning in the autumn
and the medusa stage in the spring.
Some medusæ, besides reproducing by means of eggs, multiply by
budding, small medusæ growing on the manubrium or on the margin of
the umbrella. /Sarsia/ and /Lizzia/ sometimes increase by budding.
The /Hydrozoa/ are not all of the above type. In the sertularians the
zoöids perish on the stem and have no medusa life, their reproductive
element giving rise to the hydroid form without metamorphosis. The
/Trachylinæ/ have no hydroid life, being always free-swimming medusæ;
others, the /Siphonophora/, live a hydroid life which is unattached,
the colony floating on the ocean; the millepores secrete calcareous
skeletons and always remain fixed, reproducing by budding. [pg121]
Hydroids are very abundant, but are comprised in the few groups
mentioned: namely, those which live only in the fixed colonial state;
those which have alternation of generation, being first hydroids
and then swimming-bells, or medusæ; those which live always in the
medusa state, the eggs of the jellyfish developing at once into
other medusæ; and the /Siphonophora/, or those which have a floating
colonial state, the hydroid never being attached, but floating at
large and capable of locomotion, some of the colony having the
function of propulsion.
Hydroids are particularly interesting as exemplifying the close
resemblance that may exist in outward appearance between animal and
vegetable life and as illustrations of communal life and of the
alternation of generation. A few examples of different types are
given below.
ORDER =LEPTOLINIÆ=
The members of this order agree in all essential particulars being
branched colonies having two principal forms of zoöids, the nutritive
and the reproductive. Some genera attain the length of several
inches, or even feet; others are very small tufts growing on shells
and seaweeds. The cup may completely inclose the zoöid and be close
to the stem (sessile), as in sertularians; it may be on the end of
a short stalk, as in campanularians; or it may not reach above the
base of the zoöid, as in tubularians. The genera are based upon these
differences in the perisarc.
The hydroids, like all other classes, exist in such great variety
that it would be impracticable to describe here the many named
species; but to recognize the genera is simple. A long tubular
pedicel without a cup is characteristic of the tubularians; the
campanularians have an arborescent form and bell-shaped cups on
stalks; the sertularians have sessile cups; and the plumularians have
a feather-like form, with zoöid-cups on one side only of the branches.
The beautiful and varied structure of these "animal plants" is most
interesting, and to be fully appreciated they should be seen [pg122]
in life and examined with a glass. Some species are confined to deep
water, but many are littoral and to be found in tide-pools, in the
chinks and crannies of rocks, under stones, and under the hanging
/Fucus/. The horny skeletons of large varieties are frequently washed
ashore, and in their tangled masses smaller living species often may
be found.
THE TUBULARIANS
This division is characterized by zoöids borne on long, slender stems
which are sometimes simple and small, sometimes branching and eight
to ten inches long. The zoöid has two rows of tentacles, the central
one being sometimes on a kind of proboscis. The reproductive zoöids
are in bunches, sometimes below the outer row of tentacles, sometimes
between the two rows. The perisarc does not cover the zoöid. In color
they are commonly red or yellow.
GENUS ^Clava^
^C. leptostyla.^ This species is found growing on /Fucus/, on the
under side of stones at low-water mark, and in tide-pools, where
it often covers several feet of the surface of the rock with a
delicate velvet-like carpet. It is red in color and is, apparently,
a soft and tender species, but it thrives on the most exposed
beaches. The colonies are cylindrical tubes about one quarter of an
inch in height, rising from a creeping stem (/hydrorhiza/). Each
tube is surmounted by a zoöid with fifteen to thirty tentacles,
which is constantly changing form by its contractions. Below the
tentacles are reproductive buds arranged in clusters. Common from
Long Island Sound northward. (Plate XLI.)
[Illustration: PLATE XLI. Clava leptostyla. Tubularia indivisa.
Hybocodon prolifer. Coryne mirabilis. Eudendrium ramosum. Tubularia
Couthouyi.]
GENUS ^Hydractinia^
^H. polyclina.^ The soft, pinkish covering often seen on shells
inhabited by hermit-crabs. This association of two different
kinds of animals is known as /commensalism/, and is a partnership
formed for the benefit of one or both the individuals. In this
case the mossy appearance of the hydroid conceals the shell,
while the stinging-cells with which it is invested are weapons of
defense against the enemies of the crab and also help to paralyze
its prey. In return for these favors the colony is moved about,
thereby obtaining perhaps better oxygenation. Originally it was
thought that /Hydractinia/ lived only on the shells occupied by
hermit-crabs, and that the nomadic life was essential to its
existence; but this is not the case, for it is also found growing
on rocks in tide-pools. These colonies arise from a creeping stem,
which forms a horny, root-like [pg123] network over a surface
and develops at intervals projecting points on which the zoöids
live. Each colony consists of feeding members, of reproductive
members, and of a third kind which seems to have a protective
function. These last are more slender than the others, and are
without tentacles, but are armed with lasso- or stinging-cells. The
colonies are of different sexes, the male being lighter in color
than the female colonies. The eggs develop into planulæ, which swim
about for a while and then give rise to other colonies. It is found
from New Jersey northward, and is very abundant in Long Island
Sound.
GENUS ^Coryne^
^C. mirabilis.^ A hydroid about one inch high, growing in patches
and appearing like tufts of moss on rocks between tide-marks.
When highly magnified it shows club-shaped tubes with pedicels,
terminating in zoöids, scattered over the swollen ends. The
medusa-bud is larger than the others and is lower on the tube. It
liberates a swimming-bell, which is called /Sarsia/. (Plate XLI.)
[Illustration: Colony of /Coryne/, natural size.]
^Sarsia^
^S. mirabilis.^ This medusa of /Coryne/ is from one quarter to
three quarters of an inch in diameter when full-grown. Its umbrella
is nearly hemispherical, and from the center hangs a manubrium.
From the margin of the umbrella hang four very long tentacles. The
shape of its body and the length of its tentacles and proboscis are
constantly changing as it moves in the water. These little medusæ
are very plentiful in the spring and summer, and swim rapidly in
all directions near the surface of the water.
[Illustration: /Sarsia/, the free medusa of /Coryne/.]
GENUS ^Tubularia^
^T. Couthouyi.^ This species is found in the same places as
/Parypha crocea/. The stem is three to six inches long, and is
inclosed in a horny sheath, which is more or less ringed or
jointed, or it may be smooth throughout. The head, when the
tentacles are expanded, measures one and a half inches in diameter.
It has a proboscis covered with tentacles, disposed in series,
which grow successively shorter, the last being merely papillæ. The
medusa-buds hang in clusters between the outer tentacles and the
proboscis. The animal grows in bunches of five to ten tubes, which
spring from a creeping, tangled stem. (Plate XLI.)
GENUS ^Parypha^
^P. crocea.^ This is one of the most beautiful of the tubularians.
It has a large, drooping head on a stem three to [pg124] four
inches long. It is bright red in color, and from the center of the
circle of tentacles the reproductive zoöids hang in a cluster, like
a bunch of grapes. It does not liberate swimming-bells. It is found
in bunches on piles of wharves and bridges, in brackish water, on
the eastern coast as far south as Charleston, South Carolina.
^Corymorpha pendula.^ See Plate XLII.
GENUS ^Hybocodon^
^H. prolifer.^ One of the largest tubularians, somewhat resembling
/Parypha crocea/. It is deep orange in color, and the head is
erect on a long stem. The reproductive zoöids are in a cluster in
the center of a double row of tentacles, and resemble a basket of
fruit. It grows singly, or in groups of two or three, in shaded
tide-pools, which are protected from the surf, and in which the
water is very pure. It is found on the Massachusetts coast, but is
not common. This species liberates swimming-bells. (Plate XLI.)
GENUS ^Pennaria^
^P. tiarella.^ The branches are arranged alternately and at right
angles to a central stem or axis; they taper, being shortest at
the top and bottom of the stem. The zoöids are red in color, and
are arranged along the upper side of branches at considerable
intervals. The stems are black and beaded, being constricted at
intervals. The zoöids have two rows of tentacles, the upper ones
on a small proboscis. From the lower part of the proboscis deep,
bell-shaped bodies, which eventually become swimming-bells, are
developed. The species is found on rocks and eel-grass along the
whole eastern coast.
[Illustration: /Pennaria tiarella/; a branch, natural size.]
^P. gibbosa.^ A species similar to /P. tiarella/, found on the
coast of Florida.
[Illustration: PLATE XLII. Corymorpha pendula. Clytia bicophora.]
[Illustration: PLATE XLII, A. Obelia longissima. Clytia poterium.
Sertularia pumila.]
GENUS ^Bougainvillea^
^B. superciliaris.^ This hydroid is found in tide-pools on the
New England coast, growing in clusters, about two inches high,
attached to rocks or to mussel-shells. The stem is very slender,
and branches. It is red in color. The medusæ which it liberates
are found in great numbers in the spring. The tiny swimming-bells
are nearly globular. The tentacles are long, are arranged in
four clusters on the margin, and extend in every direction. The
manubrium is yellow and short, and the mouth is concealed by four
clusters of short tentacles. On these oral tentacles [pg125]
the eggs of the animal are produced. In its habits it is sluggish,
often remaining in one position for several days.
THE CAMPANULARIANS
The hydroids which have an open, bell-shaped cup at the termination
of a short, stalk-like stem, or branchlet, are mostly campanularians.
This division embraces jellyfishes of different families. Many medusæ
cannot be referred with certainty to the hydroids from which they
sprang, and the medusa-buds of many of the hydroids have not been
noted.
GENUS ^Obelia^ (Plate XLII, A)
^O. commissuralis.^ This is a delicate, much-branched hydroid, five
to six inches long, found at low-water mark in tide-pools, attached
to stones and seaweeds, along the rocky shores from Nova Scotia
to South Carolina. Its branches are arranged spirally and spread
nearly at right angles to the main stem, and the main branches
subdivide in a similar manner. Every interval of the stem has a
slight curve, and at the base of every branch there are four or
five rings. The ultimate branches, or pedicels, bear at their ends
bell-shaped cups which have even edges, but are twelve-sided and
slightly incurved. The pedicels are ringed for the whole length.
The reproductive cups on short ringed pedicels are larger than
the others, and occupy the angles of the branches. These cups are
constricted and again expanded at the apex, forming an urn-like top.
GENUS ^Eucope^
^E. diaphana.^ This species is often abundant on the fronds of
/Laminaria/ washed ashore, and also on /Rhodymenia/ and /Fucus/.
It has a creeping base, zigzag in form, but keeping a straight
course, and in its branching often forming a network over the
surface of the flat fronds. At each angle of the creeping stems
rises a pedicel about an inch high, which inclines in the direction
of the stem and terminates in a zoöid-cup similar in form to that
of /Obelia/. The medusa which this hydroid liberates is called
/Thaumatias diaphana/. The swimming-bell is very shallow and thin,
turning inside out at almost every pulsation. The tentacles are
numerous and rigid like stiff hairs. This little medusa is very
active and is abundant. The species is found from Long Island Sound
northward.
GENUS ^Oceania^
^O. languida.^ This medusa is one inch in diameter and one half of
an inch high, and is so delicate and transparent that it is hardly
visible except in its outlines. In its early stages it is nearly
spherical and has no tentacles; later the disk flattens and has
from thirty-two to thirty-six [pg126] tentacles and numerous
eye-spots. When disturbed it flattens its disk and folds together,
leaving its tentacles sprawled in every direction. It is very
languid in its movements, and often remains in one position for
hours. These medusæ are found only in the hottest hours of the day,
but are very plentiful then, shoals of them often stretching for
miles, and so thick as to touch one another. Their habitat is the
New England coast.
GENUS ^Clytia^
^C. poterium.^ This hydroid is found creeping over seaweeds in
tide-pools from Long Island Sound northward. The main stem is
prostrate, or root-like, running over the body to which it is
attached. The stems rise as do the tubularians. The sterile zoöids
are on single stems about one quarter of an inch high. The stems
are faintly ringed for their entire length, and at the top have
a distinct ring, on which rests an open, bell-shaped cup, which
is smooth around the rim. The reproductive zoöids are on very
short pedicels, and the cups are long and cylindrical, with a wavy
outline. (Plate XLII, A.)
^C. bicophora.^ This species is found in the same places as the
preceding, and is of about the same size. The long stems are more
or less ringed and sometimes branched. The edges of the cups are
notched. The medusa-buds are urn-shaped and ringed, and are on very
short pedicels. (Plate XLII.)
THE SERTULARIANS
The sertularians are distinguished by the horny cup, which is
sessile—that is, set directly against the stem instead of being
raised upon a stalk. They are among the most common objects of the
beach, and, like the plumularians, are often mistaken for plants by
the amateur collector and are gathered and pressed as seaweeds. They
are found everywhere along the coast. They zigzag over the fronds of
seaweeds or hang in fringes upon them, as well as upon rocks, stones,
and shells. They well repay close examination with a glass. Every
open cup bears a wreath of tentacles, which makes the branch a spray
of stars. This is not an inappropriate comparison, for besides their
starry shape some species emit a phosphorescent light.
[Illustration: PLATE XLII, B. Sertularia argentea. Sertularia
cupressina.]
[Illustration: PLATE XLIII. Plumularian hydroid. Aglaophemia
struthioides. Aglaophemia struthioides, magnified. Plumularia
falcata.]
GENUS ^Sertularia^
^S. pumila.^ The most abundant of all the hydroids on the northeast
coast is this species, which is found in profusion upon /Fucus/
and other seaweeds, and mingled with them upon the rocks. It
is easily distinguished from the campanularians because its
zoöid-cups are close against the stems (sessile) instead of on
stalks or pedicels. The stem creeps [pg127] over the fronds
of seaweeds, often crossing and recrossing in a tangled mass. At
short intervals the upright, straight branches rise to one inch or
one and a half inches in height, and are more or less branched.
All except the creeping stems are close set on each side, with
cylindrical zoöid-cups which turn outward at the ends. The cups of
the reproductive zoöids are not sessile; they are much larger than
those of the nutritive ones and are urn-shaped. (Plate XLII, A.)
^S. argentea.^ This is a beautiful species, common from New Jersey
northward. It has a profusion of silvery branches on a dark stem.
The colonies are often a foot or more long, and the branches at
the top and bottom of the stem are shorter and fewer than those in
the middle of the colony. The zoöid-cups are nearly cylindrical,
pressed closely to the stem, nearly opposite or subalternate to one
another, and end in pointed tips. The medusa-bud is urn-shaped,
with two horns at the top. (Plate XLII, B.)
^S. cupressina^, the sea-cypress. This species is similar to
/S. argentea/, but the main stem is thicker and longer, and the
branches less crowded and less subdivided. The branches are arched
or drooping, instead of straight, and gradually decrease in length
at some distance from the lower and upper parts of the stem,
giving a spire-like apex, the stem often continuing into a bare,
branchless extremity. The zoöid-cups are tubular, not much narrowed
or divergent above, and two-lipped on the margin. It is found from
New Jersey northward. (Plate XLII, B.)
THE PLUMULARIANS
These hydroids are feather-like in the manner of branching, short
lateral branches being arranged on each side of a long central stem.
In some species the stems are naked below and resemble quills. The
zoöid-cups are only on one side of the short branches. (Plate XLIII.)
GENUS ^Aglaophemia^
^A. struthioides^, the ostrich-plume. This species, which is
found on the Pacific coast, is perhaps the most beautiful of the
hydroids. It varies in size and color, but always suggests a small
ostrich-plume. The zoöid-cups are arranged in a single row on one
side of each short branch, and the main stem has a joint between
each of the branches, which are placed quite close together. The
rims of the cups have sharp-pointed teeth, and from the top emerge
three tubular projections, which are called /nematophores/, and are
supposed to be degenerate zoöids. At intervals a branch is replaced
by a cylindrical body covered with nematophores, and in these the
generative zoöids are developed. (Plate XLIII.)
GENUS ^Plumularia^
^P. falcata^ (Johnston), or ^Hydrallmania falcata^ (Hincks). This
species is found on shells and rocks near low-water mark from Long
[pg128] Island Sound northward. It is from four to twelve inches
high. The main stem is in long spiral turns, and at intervals has
spreading plumose branches. The zoöid-cups are tubular and closely
pressed against one another, and are ranged in rows on one side of
the branchlets; the apertures of the cups are plain and oblique.
(Plate XLIII.)
FAMILY ~GERYONOPSIDÆ~
GENUS ^Tima^
^T. formosa.^ A very delicate and transparent medusa; size one to
two inches in diameter; bell conical; radial tubes four in number;
manubrium long, hanging far below the disk; four frilled appendages
diverging from the corners of the mouth; tentacles thirty-two;
egg-sacs white and following the line of the radial tubes in
undulating folds. This species is not very common; it is found on
the New England coast.
FAMILY ~ÆQUOREIDÆ~
GENUS ^Zygodactyla^
[Illustration: /Zygodactyla groenlandica./]
^Z. groenlandica.^ Medusa seven to eleven inches in diameter; disk
violet-colored and transparent; margin fringed with long, fine,
contractile tentacles of a darker violet color; numerous radiating
tubes; egg-sacs in slightly waved plates; manubrium hanging below
the line of the disk and with a thin frilled membrane depending
from it. Found north of Cape Cod in July.
ORDER =TRACHYLINÆ=
The /Trachymedusæ/ are characterized by their direct development, the
egg of the jellyfish producing a medusa and not a hydroid colony.
GENUS ^Trachynema^
^T. digitale.^ Size one inch to one and a half inches in height;
rose-colored; the bell thin and hard, and conical at the top. The
swimming is effected by contractions of the muscular velum (the
band around the inner margin of the umbrella) instead of wholly by
the bell. The tentacles are long and numerous, and are curled up
when moving. The manubrium is long and has four expansions at the
mouth. Eight egg-cases [pg129] hang in long pendent sacs from the
upper part of the radial canals and reach nearly to the velum. Four
garnet-colored eyes in club-shaped processes are prominent on the
margin. The animal moves by jerks in straight lines.
ORDER =HYDROCORALLINA=
CALCAREOUS HYDROIDS
[Illustration: /Trachynema digitale./]
The genus ^Millepora^ ("thousand pores"), which is the type of this
order, is a colony of animals, like other hydroids, which secrete
calcareous instead of horny coverings. It differs from true corals
in that the members of a colony perform different functions, whereas
in true corals each member of a community is a complete individual.
It differs also in the arrangement of the stony partitions, which in
=Hydrocorallina= are the outside coverings and connecting canals, but
in true corals are vertical partitions inside the animal, between the
inner and outer sacs, as explained on page 114.
GENUS ^Millepora^
^M. alcicornis^, elk-horn coral. This beautiful coral, which is
abundant in Florida and contributes to the building of the reefs,
rises in broad expansions, more or less lobed, and suggests by its
shape the object for which it is named. The whole mass is porous,
being traversed by innumerable canals. Its surface, although
smooth compared with that of other corals, is covered with very
minute pores, which are of two sizes. The larger ones are the
/gastropores/, or stomach-pores, in which the nutritive animal
lives; it has a cylindrical body, with four knob-like tentacles and
a mouth. Placed more or less irregularly around the gastropores are
smaller pores, the /dactylopores/ (finger-pores), from which emerge
slender mouthless processes, or /dactylozoöids/, with tentacles and
stinging-cells. These seem to be the guard-polyps of the community.
The cups occupied by the zoöids are shallow. As one animal dies,
another succeeds it and builds a horizontal partition separating
the new cup from the old one. Thus the stony mass increases in size
by the progress of succeeding generations of zoöids. The living
animal occupies only the outer, open space. (Plate XLIV.) [pg130]
ORDER =SIPHONOPHORA=
FREE-SWIMMING COLONIES
This order of hydroids consists of free-floating communities and
is one of peculiar interest, since it shows in a clear manner the
special function of each individual member of the colony, and
illustrates better than the foregoing, perhaps, the curious forms of
animal life which this class presents.
GENUS ^Nanomia^
[Illustration: Adult /Nanomia cara/.]
^N. cara.^ This species is found on the New England coast. The
members of the community are arranged along a hollow stem about
three inches long which opens into every individual. At the top
of the stem is a sac, or float; just below this is a group of
swimming-bells which have no manubrium or mouth, and whose sole
function is to provide locomotion for the community; and below
these are three sets of zoöids, each having a triangular shield
and tentacles. The tentacles are longer than the main stem. One of
these last groups consists of the nutritive members, the mouths
of the community, resembling manubriums of swimming-bells out of
place. Each one has at the point of attachment a bunch of long,
delicate tentacles having pendent knobs of lasso-cells. A second
group, also with mouths, has shorter tentacles which are carried in
spiral coils. The members of the third group have but one tentacle
each and resemble the float at the end of the stem; presumably
these drop off and produce new colonies. There are also on the
lower part of the stem other reproductive members, which resemble
the clusters of buds seen on [pg131] tubularian hydroids. These
animals are pink in color and move through the water with a
graceful swaying motion.
GENUS ^Physalia^
[Illustration: /Physalia arethusa/; Portuguese man-of-war, one fifth
natural size.]
^P. arethusa^, the Portuguese man-of-war. This colony is perhaps
the best-known one of the group, since it attracts much attention
in Southern waters, and is also one of the most remarkable
examples of an animal community. The most prominent part of the
compound body is the float, an oblong pear-shaped bag, full of
air, which floats on the surface of the water. Its color is bright
blue, varying to rose. On the upper side of this air-vessel is a
crest, or sail, and from the under side depend long tentacles, or
streamers. Some of these tentacles are covered with stinging- or
lasso-cells; some are the feeding zoöids, with flask-shaped
bodies, and some, which look like bunches of grapes, are the
reproductive zoöids. The tentacles in this curious cluster are
all close together and hang from one side of the float, near the
broader end. The longest are on the outside, which may be called
the windward side, since they serve to keep the crest, or sail,
before the wind; and when the wind is strong they stretch out to
a remarkable length,—forty to fifty feet,—acting as anchors to
keep the colony from being driven ashore. They also change its
course by raising the pointed end of the float, thus forcing it to
"come about." These long tentacles, ordinarily carried more or less
curled up, are in bunches of two to four, and emerge from a common
stem. Clusters of similar, but smaller, tentacles alternate with
the larger ones, but grow somewhat nearer the pointed end of the
float; these are purely locomotive organs. Next come two smaller
sets of appendages, also of unequal size, which are the nutritive
organs of the community. They are clustered together on a stem like
the others. The appendages of the third kind are small, resemble
bunches of grapes, and are scattered among the nutritive hydræ.
These last are the reproductive zoöids of the community.
GENUS ^Vellela^
^V. limbosa.^ This hydroid is abundant on the Florida coast. It
has a bright-blue, flattened, oblong, bladder-like float, four to
five inches [pg132] long, which, is divided into a number of
concentric, communicating compartments. The margin of the float is
entire, and a triangular sail extends diagonally across the top. On
the under side is a single mouth on a manubrium, and surrounding it
are a large number of short thread-like appendages having different
functions. Some of them are feelers, others bear reproductive buds,
and others have stinging-cells. Associated with /Vellela/ is an
allied hydroid called /Porpita/, which has no sail, and in company
with these two is a jellyfish called /Rataria/, which is supposed
to be the offspring of one or the other of them.
[Illustration: /Vellela limbosa./]
TABLE SHOWING THE CLASSIFICATION OF THE SCYPHOZOA DESCRIBED IN THIS
CHAPTER
Class =SCYPHOZOA= (/Velum usually absent and tentaculocysts
present; the eggs are discharged into a gastric cavity. The type
of this class is Aurelia/)
Order =STAUROMEDUSÆ= (/Umbrella conical or vase-shaped; no
tentaculocysts/)
Genera Species
^Lucernaria^ ^L. auricula^
Order =PEROMEDUSÆ= (/Umbrella conical and divided by transverse
constrictions; four interradial tentaculocysts/)
^Pericolpa^ ^P. quadrigata^
Order =CUBOMEDUSÆ= (/Umbrella four-sided, cup-shaped; four
perradial tentaculocysts/)
^Charybdæa^ ^C. marsupialis^
Order =DISCOMEDUSÆ= (/Flattened, saucer-like or disk-shaped
umbrella; radial tubes branched; eight tentaculocysts/)
Suborder ~CONNOSTOMÆ~ (/Very small; marginal tentacles; short
and solid; mouth square without arms/)
Suborder ~SEMOSTOMÆ~ (/Square mouth with four long arms;
tentacles long and hollow/)
^Aurelia^ ^A. flavidula^
^Cyanea^ ^C. arctica^
^C. fulva^
^C. versicolor^
^Linerges^ ^L. mercurius^
^Pelagia^ ^P. cyanella^
Suborder ~RHIZOSTOMÆ~ ("/Root-mouth/") (/Mouth obliterated by
growth of oral arms across it; tentacles absent/)
^Cassiopeia^ ^C. frondosa^
[pg134]
CLASS =SCYPHOZOA=
THE LARGE JELLYFISHES
There is perhaps no marine animal which excites more wonder than
the jellyfish. Its transparency, its graceful rhythmical movements,
its long streaming tentacles, the variety and eccentricity of its
form, and often of its color, attract attention, and one naturally
desires to know something of its life-history. Jellyfishes are also
called /medusæ/, because their long appendages suggest the locks of
the Gorgon; /acalephs/, on account of their stinging or nettle-like
properties; and sun-jellies, sea-blubbers, etc., because they float
upon the surface during the warmest part of the day, when the sun is
high. The name /jellyfish/ is inappropriate, since the animal in no
way resembles a fish except in the fact that it swims; but it is,
nevertheless, the commonest name.
Jellyfishes vary in size from that of a pinhead to six or seven
feet in diameter. They differ in the number, size, and position of
the tentacles, the number of the radial canals, the form of the
manubrium, the position of the egg-sacs, etc.; but the general plan
of the internal structure is the same in all species. In shape they
are compared to a mushroom. From the center of an umbrella-like top
falls a central organ like the stalk of a mushroom. It is called the
/manubrium/ and is the mouth and stomach of the animal.
From the top of the manubrium radiate straight or branched tubes,
which are connected with a canal which runs around the whole margin
of the umbrella. Extending around the inner circumference of the
disk in certain species (usually the hydroid medusæ), there is a
horizontal shelf, called the /velum/, or veil, because it sometimes
falls like a veil. [pg135]
From the margin of the umbrella depend the tentacles. There are
little mineral deposits, like crystals, called /lithocysts/, disposed
at intervals on the margin, and known also as /marginal bodies/,
which are supposed to be eyes. In some species these lithocysts
are inclosed in club-shaped bodies, and they are then called
/tentaculocysts/, because they are like small tentacles. These,
together with the nerve-fibers, are called the sense-organs; but to
what extent jellyfishes can see and feel is undetermined. This is
the first appearance of sense-organs in animals. Around the concave
surface of the umbrella is a muscular zone, or zone of contractile
tissue, by which the animal opens and shuts the umbrella and gets its
locomotive power. The /gonads/, which are conspicuous from being more
opaque than the rest of the body, are the egg- or sperm-sacs. They
vary in form and in position.
The jellyfish is carnivorous, feeding on small organisms such
as crustaceans and even fishes. The tentacles are invested with
stinging-cells, as are also the frills about the mouth, when such
occur. With these stinging-cells, which are in some species so
powerful as to have been compared with an electric battery, the
jellyfish benumbs its prey. The stinging properties are due to
nettle-like threads contained in poison-cells. When these penetrate
the flesh they produce a pain similar to that of an electric shock.
The food is taken into the manubrium by the square mouth at its
free end, and is there digested. It is then sent as nutritive fluid
through the canal system of the body, and ejected through small pores
in the canal which surrounds the margin of the umbrella.
There are two sexes. The gonads of the female contain eggs; those of
the male, sperms. The contents of the gonads drop into the central
cavity and pass out through the mouth. The fertilized ovum is called
a /planula/, and is a transparent sphere covered with cilia, by
means of which it swims about for a time. At length it attaches
itself to some object, and becomes in some species a branching colony
(hydroid), in other species a /strobila/. The latter, as it grows,
is constricted at intervals, and at maturity resembles a pile of
inverted saucers with lobed edges. Each of [pg136] these saucers
is finally detached, and when liberated is called an /ephyrula/,
and becomes a jellyfish. Thus its cycle of life is complete. There
are some species which, having no hydroid or strobila state, mature
without alternation of generation (/metagenesis/).
The term of life of the jellyfish does not exceed one year. Even the
giant /Cyanea/ attains its immense growth in six months. It starts
in the spring as an ephyrula, not more than one half of an inch in
diameter, and when it dies in the autumn is often six to eight feet
in diameter. The bodies of jellyfishes are ninety-nine per cent.
water, and the dead ones thrown upon the beaches by the autumn storms
rapidly disappear, leaving no traces behind.
The powerful stinging-cells with which the large medusæ are armed
make them formidable enemies, and it is probable that some deaths
by drowning are caused by swimmers encountering them and becoming
paralyzed by them.
ORDER =STAUROMEDUSÆ=
("/Cross-medusæ/")
GENUS ^Lucernaria^
^L. auricula.^ This little iridescent jellyfish, which measures
about one and a half inches in diameter, is commonly found attached
to eel-grass by a stalk-like projection of the top of the umbrella.
Short, globe-tipped tentacles are arranged in eight clusters, each
cluster on a raised prolongation of the margin of the umbrella, and
in the center of each space between them is a dark kidney-shaped
organ called the /anchor/. These anchors are used for holding,
either for suspension or when moving from place to place. The
mouth forms a slight quadrangular projection in the center of the
bell-like expansion. The arm-like projections are mottled with
two rows of spots, which are the ova. Although a free form and
capable of moving about, /Lucernaria/ is sedentary in habit. It is
sometimes found free, but generally attached by its extremity to
eel-grass or /Fucus/, seldom to rocks. It is constantly changing
its shape. The one it most frequently assumes is that of a cup or
inverted bell. It is found on the New England coast. (Plate XLIV.)
ORDER =PEROMEDUSÆ=
("/Maimed medusæ/")
GENUS ^Pericolpa^
^P. quadrigata.^ Umbrella conical and divided by a horizontal
constriction into two parts, the lower one being again divided into
lobes. There are four long tentacles and four tentaculocysts. It is
not found on the coasts of the United States. [pg137]
ORDER =CUBOMEDUSÆ=
("/Cube-medusæ/")
GENUS ^Charybdæa^
^C. marsupialis.^ Umbrella square, flattened on top, and of firm
consistency. Four tentacles fall from lobes on the umbrella, and
four club-shaped eyes are in marginal notches. Plate-like egg-sacs
follow each side of the four radial canals. The bell is one inch
in diameter and about two inches in height. It is not found on the
coasts of the United States.
ORDER =DISCOMEDUSÆ=
("/Disk-medusæ/")
SUBORDER ~SEMOSTOMÆ~
GENUS ^Aurelia^
[Illustration: /Aurelia flavidula/, about one fourth natural size.]
^A. flavidula.^ Size eight to ten inches in diameter; disk
gelatinous, transparent bluish-white, broad and comparatively flat,
with a fringe of short tentacles of even length around the margin;
margin broken by eight notches, in each one of which is a club-like
organ (/tentaculocyst/) containing calcareous spots or eyes, which
are hidden by lappets or hood-like coverings; groups of nerve-cells
also lie in the marginal notches; radial canals branched; manubrium
very short, with square mouth, which is surrounded by delicate
membranes, or oral arms, each arm being a folded membrane tapering
to a point. The edges of the membranes are covered with lasso- or
stinging-cells. Four egg-sacs, or gonads, are conspicuous in
horseshoe shape around the center of the disk. The gonads are
pink in the males, and yellow in the females. These medusæ swim
in shoals, and are common everywhere in summer. They may be said
to be annual animals, for they make their appearance regularly as
free-swimming medusæ in the latter part of April, when they may be
seen in immense numbers near the surface when the water is smooth
and the sky clear. At this time they are about an inch in diameter.
They grow rapidly, and by the end of June have attained their full
size. At [pg138] the end of July they are fully developed, and
begin to discharge their eggs, which go into the folds around the
mouth and remain there until they attain the planula stage. After
the spawning period the medusæ, reduced in strength, are unable
to resist the storms of the autumn, and many of them are cast
ashore; many others, in a more or less wasted condition, float
near the surface, but the body is less transparent, its tissues
are thickened, its tentacles gone, and general dissolution has
commenced. In this condition the medusæ are frequently capsized by
the air which accumulates in the empty egg-cavities, and, floating
helplessly on the surface, are attacked and destroyed by swarms of
small crustaceans; thus their cycle of life is terminated. It has
been suggested that the destruction of the mothers, by being cast
upon the beaches in the autumnal gales, is a provision to set free
the planulæ in a position favorable to their existence; for when
liberated they fasten upon the rocks and seaweeds of the shore,
where, during the winter months, they develop into strobilæ, which
in turn free their saucer-like disks early in April.
[Illustration: Strobila of /Aurelia flavidula/.]
GENUS ^Cyanea^
[Illustration: /Cyanea arctica/, greatly reduced in size.]
^C. arctica^, the sun-jelly or sea-blubber. This is the largest
jellyfish known. Some individuals measure seven and a half feet
across the disk and have tentacles more than one hundred feet long.
Usually they are three to five feet in diameter, with tentacles
thirty to forty feet long. The disk is red, the margin white and
scalloped. The tentacles, of different colors, are covered with
lasso- or stinging-cells, and are arranged in eight distinct,
thick clusters on the margin. From the mouth hang four long and
very broad, thin curtains, much folded and ruffled, whose edges at
times look as if they were embroidered, because great numbers of
discharged eggs are attached to them. Four egg-sacs hang from the
disk near the manubrium, and eight sense-organs (tentaculocysts),
in hardened coverings, lie in some of the deep incisions of the
margin. /Cyanea/ [pg139] is usually solitary, seldom being seen
in company with others. It is common on the New England coast,
and is frequently found stranded on the beach, where it in no way
suggests the beautiful appearance it presents when floating in
the water. Like /Aurelia/, /Cyanea/ has a strobila stage. It is
supposed that the young remain near the bottom, for they are seldom
seen, while adults are plentiful. They begin to appear in numbers
at the end of summer from Cape Cod northward.
^C. fulva.^ This species is found in midsummer south of Cape Cod
and is common in Long Island Sound. Its general color is light
yellowish-brown, the flowing curtains being the darkest part of
the animal. It is not as large as C. arctica, and the lobes of the
margin are deeper and more rounded.
^C. versicolor.^ The whole disk is bluish milky-white, the flowing
curtains are light brown, and the tentacles are pink. It is not so
large as /C. arctica/. Found in the spring on the southern coast.
[Illustration: /Linerges mercurius/, thimble-fish.]
GENUS ^Linerges^
^L. mercurius^, the thimble-fish. The English name indicates the
form as well as the size of this little brownish jellyfish, which
is found near the Florida Keys, extending in lines for considerable
distances.
GENUS ^Pelagia^
^P. cyanella.^ Umbrella spherical, margin scalloped, tentacles
eight in number; four long appendages ruffled on the edges hang
from the mouth; size about two inches in diameter; appendages four
inches long; color pink. (See next page.)
SUBORDER ~RHIZOSTOMÆ~
The =Rhizostomæ=, or root-mouth jellyfishes, are very remarkable.
They have no tentacles, but covering the end of the manubrium and
hanging from it like tentacles are oval appendages with numerous
minute funnel-like apertures, called suctorial mouths. As the manner
of locomotion of jellyfishes is peculiar to themselves, so also is
this many-mouthed development unique in the animal kingdom. The
type of this group, described below, is found on the Florida Keys.
The different species vary in diameter from three to eight inches.
[pg140]
GENUS ^Cassiopeia^
[Illustration: /Pelagia cyanella./]
^C. frondosa.^ This species has a circular disk, on the margin of
which are sixteen sense-organs (tentaculocysts), but no tentacles.
The lower end of the manubrium, which in other jellyfishes is
an open mouth, is closed by eight arms which emanate from it
and are usually extended laterally, lying parallel to the disk.
These arms are much branched, and the branches, in turn, have
numerous appendages. Some of these appendages look like little
polyps and have mouths surrounded by crowns of tentacles; others
are ovoid bodies without external openings, but with a central
cavity connected with vessels leading to the arms. The former are
mouths, but the function of the ovoid bodies is not known. Although
able to swim freely, /Cassiopeia/ lies usually on its back, as if
attached, and languidly opens and closes its disk, rarely changing
its position. Its arms, extending upward, appear like the fronds of
algæ. These jellyfishes are common on the Florida coast, huddled
together on the sands of the coral reefs. (Plate XLIV.) [pg141]
TABLE SHOWING THE CLASSIFICATION OF THE ACTINOZOA DESCRIBED IN THIS
CHAPTER
Class =ACTINOZOA=
Subclass =Zoantharia= (/Mesenteries numerous, usually in
multiples of six; tentacles unbranched hollow cones/)
Order =ACTINIARIA= (/The sea-anemones. Single; no skeleton/)
Genera Species
^Metridium^ ^M. marginatum^
^Rhodactinia^ ^R. davidsii^
^Holocampa^ ^H. producta^
^Sagartia^ ^S. leucolena^
Order =MADREPORARIA= (/The stone- or reef-corals. Colonies;
skeleton calcareous/)
^Oculina^
^Astræa^
^Meandrina^
^Diploria^ ^D. cerebriformis^
^Madrepora^ ^M. cervicornis^
^M. palmata^
^Astrangia^ ^A. danaë^
Order =ANTIPATHARIA= (/The black corals/)
Subclass =Alcyonaria or Halcyonoida= (/Tentacles and mesenteries
eight in number; tentacles feathered, that is, with uniform
branches/)
Order =ALCYONACEA=
^Alcyonium^ ^A. palmatum^
^Tubipora^
Order =GORGONACEA= (/The sea-fans and sea-whips. Compound,
tree-like colonies, with horny axis, branching throughout/)
Order =PENNATULACEA= (/Free, phosphorescent; colonies, with
horny axis; polyps in lateral branches/)
^Pennatula^
[pg142]
CLASS =ACTINOZOA=
SEA-ANEMONES, REEF-CORALS, SEA-FANS, SEA-WHIPS, AND SEA-PENS
The animals of this class are divided into two subclasses, based on
the following anatomical differences: In the first subdivision, which
includes the sea-anemones and the reef-building corals, the polyps
have numerous simple, hollow tentacles and radial partitions of the
same number, both being some multiple of six. The polyps of a colony
are all alike, and the hard matter they secrete is carbonate of lime.
In the second subdivision, the /Alcyonaria/,—or halcyonoids, as they
are commonly called,—the tentacles and radial partitions are always
eight in number, and the tentacles have small symmetrical appendages
or branches. The polyps of this group are often accompanied by
small zoöids having no tentacles. The hard secretions are horny
and elastic, as in sea-fans, sea-whips, and sea-pens, or they are
extremely hard, as in /Corallina rubrum/.
SUBCLASS =ZOANTHARIA=
("/Animal-flowers/")
ORDER =ACTINIARIA=
SEA-ANEMONES
These curious and, at times, beautiful creatures are polyps, and are
constructed on the radial system. They have a cylindrical body with
a broad base and rows of hollow tentacles around the upper disk.
They have a central sac, and a space between the outer and inner
sacs which is divided vertically by walls called /mesenteries/, as
explained on page 114. Each tentacle, however many there [pg143] may
be, has a corresponding chamber. The inner sac has a mouth, like a
slit, at the top of the disk, opening to the outside, and it also has
openings into the chambered spaces which surround it. These chambers
also open into the hollow tentacles; thus a continuous circulation
throughout the whole animal is established.
The food taken in at the mouth is digested in the inner sac, passes
through all the chambers of the cavity as nutritive fluid, and is
then expelled at the mouth again. The inner sac, or gullet, has
longitudinal grooves; two of these are broad and deep, and correspond
to the corners of the mouth. These are called /siphonoglyphs/. The
sea-anemone is soft and contractile, and belongs to the only order
of this class which does not secrete a skeleton. It has two sets of
muscles, one of which extends from the base to the summit of the body
and is placed on the dividing partitions. Sea-anemones are classified
by the arrangement of the septa and the manner in which the muscles
are placed upon them. The other set of muscles is arranged around
the circumference of the column or body. Each tentacle is furnished
with similar sets of muscles. The animal is sensitive, and at the
least alarm contracts its body by means of these muscles, and
quickly transforms itself from a beautiful, flower-like form into a
shapeless, unattractive, inconspicuous mass.
The /Actiniaria/ are developed from the egg. The eggs form on the
edges of the inner walls (mesenteries), and when mature drop into
the outer sac (gullet), and out of the mouth as ciliated spheres
(planulæ). After swimming about for a time these attach themselves to
rocks, and, conforming to the irregularities of the surface, secure a
tight hold. The upper surface of the planula then becomes depressed
and forms a gullet, and in time a complete animal is formed. The
/Actiniaria/ reproduce also by budding. A small protuberance or
simple elevation of the body-wall appears on the side at the base,
or in some species on the disk of the animal, which generally
develops into a complete animal and at maturity falls away from the
parent. Sometimes several anemones bud simultaneously from the same
individual, and a third generation commences to bud at the same
time from the immature young of the parent stock. The sea-anemones
increase [pg144] also by self-division. In this case a constriction
is formed, which gradually deepens and forms a complete partition of
the body, and two individuals exist where originally there was but
one.
The /Actiniaria/ are carnivorous and very voracious. They feed
on small organisms and on shell-fish and crustaceans, which they
suck out of their shells. To secure their prey they are armed with
an abundant supply of stinging-cells on the tentacles, and also
with fine stinging-threads which are ejected from pores which are
distributed over the whole body.
Sea-anemones vary greatly in color and form, and when expanded
suggest flowers, but do not resemble the one for which they are
named. They abound on every shore, the same genus often being found
in widely separated regions. They are larger and more highly colored
in tropical waters. Many of the species are littoral, and are found
in the tide-pools of rocky caverns, on the under side of rocks, and
on the piles of wharves and bridges at low-water mark. The majority
of them are attached, but are able to change their location; others,
/Edwardsia/ and /Cerianthus/, swim about when young, and in the
adult state burrow in the sand or mud, leaving only their tentacles
exposed. /Bucidium parasiticum/ is parasitic on the folds of the
membrane which hangs from the mouth of the large jellyfish /Cyanea
arctica/. /Fenja/ and /Peachia/ lie on the sea-bottom, with their
bodies horizontal like a worm, the mouth-end and tentacles erect.
/Adamsia palliata/ furnishes another example of commensalism; it
lives on the back of shells, commonly the whelk, inhabited by
hermit-crabs. /Minyas/ is pelagic; it has a float at one end, and by
means of its tentacles swims about freely.
A very few species only are described below, since these polyps are
unmistakable, being always columnar bodies, with the upper disk more
or less crowded with tentacles, and so brilliant in coloring and
beautiful in form as to attract attention if found in the expanded
state; otherwise they are easily overlooked.
GENUS ^Metridium^
^M. marginatum.^ This is the most conspicuous and abundant
sea-anemone of the northeastern coast. It is common from New York
[pg145] northward, and is found near low-water mark in tide-pools,
on the under side of large stones, in sheltered crevices of rocks,
and on the piles of wharves and bridges. In contraction it is a
broad, low cone, but when expanded is sometimes ten inches across
the disk. Allied species found in Florida are eighteen inches in
diameter. The column is smooth, cylindrical, and broader than
long. At the top is a slightly elevated, thickened fold, and
above this a deeply folded and frilled margin, with numerous
fine, short tentacles, appearing like a fringe, which cover the
upper side of the disk half-way to the oval mouth. The color is
exceedingly variable; commonly the column is yellowish-brown, but
it may be pink, white, salmon, orange, or dark brown, or striped
or mottled with different colors. The disk and folds are lighter
or flesh-colored, and the tentacles are of varying colors, usually
grayish with tips of brighter colors. When irritated this species
throws out from the column numbers of long, slender white threads
(/acontia/), which are covered with minute stinging-cells. These
organs of defense protect the animal from the attacks of many
enemies.
GENUS ^Rhodactinia^
^R. davidsii^ (Agassiz), ^Tealia crassiformis^ (Gosse), the
thick-petaled rose-anemone. The color varies, being often
bluish-green mottled with crimson, often bright cherry-red, with
the thick tentacles somewhat lighter in shade, or flesh-colored.
The animal is found in shallow water. It assumes various shapes,
changing every few minutes. The tentacles are short, conical, and
uniform in size; the column, the breadth of which is greater than
its height, often has wart-like processes in longitudinal lines.
The diameter of the disk is about three inches. Found from Cape Cod
northward in tide-pools and on ledges covered with /Fucus/.
GENUS ^Holocampa^
^H. producta.^ Its column, stretched to its full extent, is a foot
in length and about an inch in diameter, but when contracted is
much shorter and thicker. It has but twenty tentacles, and these
have swollen tips. Rows of suckers extend the length of the column.
It ranges from Cape Cod to South Carolina, and is found under rocks
at low-tide mark, and also on sandy beaches, buried in the sand,
with its tentacles only above the surface.
GENUS ^Sagartia^
^S. leucolena^, the white-armed anemone. It ranges from Cape Cod
to North Carolina, and is common in Long Island Sound, being found
at low-water mark on the under side of stones. The column is
elongated, cylindrical, translucent, flesh-colored, with simple
plain disk and long, slender, whitish tentacles crowded together
near the margin. [pg146]
ORDER =MADREPORARIA=
STONE- OR REEF-CORALS
The coral resembles the sea-anemone and is a polyp constructed on the
radial plan (page 113). It lives in colonies, but, unlike the hydroid
colonies, each polyp of the community is a complete organism, and
in the reef-building corals all the individual polyps of a colony
are alike. The home of each animal is called a /corallite/, and the
aggregation of many corallites is a /corallum/.
The corallite is composed of carbonate of lime secreted by the polyp,
and, broadly speaking, may be called a skeleton. The secretion forms
a basal plate and radiating partitions between the mesenteries in
the cavity of the animal, and also surrounds the polyp like a cup.
In some species this is a solid substance; in others it is like a
network through which the animal substance (cœnosarc) of the
zoöids of the colony is connected, as in /Madrepora/.
The polyps reproduce by budding and by self-division (fission),
in a manner similar to that of sea-anemones. The way in which the
budding or the fission takes place determines the shape of the
colony, or corallum, which has a great variety of forms. In some
species the budding is confined to certain individuals of the colony.
In this case the branched forms result. When growth takes place by
fission, hemispherical masses are formed, which are often perfectly
symmetrical, as in the so-called brain-corals. In /Astræa/ the polyps
are inclosed separately, but in /Meandrina/ fission is confined to
the upper half of the polyps, so that a complex polyp is formed, with
several mouths opening into a common stomach, making long serpentine
furrows on the corallum.
Some of the genera of the second subdivision, the alcyonarians,
differ materially from the ordinary idea of corals, as their
framework is of a horny and more or less flexible material (chitin).
Of these are the sea-fans, sea-whips, and sea-pens. The organ-pipe
coral of the same subdivision is an example of an exceedingly
fragile lime structure, while the red coral, /Corallina rubrum/,
[pg147] the species so much used for ornamental purposes, has an
exceedingly hard and stony character. The madrepore corals are called
reef-builders, but not in the sense of constructors of reefs. They do
not erect definite structures as bees do. It is the aggregation of
the skeletons of the dead polyps, together with other agencies, which
forms a reef. The coral polyps, though so minute individually, are
almost infinite in numbers. It is estimated that the colonies rise
one half of an inch in ten years.
Corals live at different depths in the sea. Those which form the base
of the reef are the astræans, which do not live above a depth of six
fathoms. They are characterized by little star-shaped spots on the
corallum, the radial partitions meeting in the center of the spots,
or corallites. Next above the astræans come the mæandrinas and the
porites. The former have elongated openings which extend in waving
furrows over the surface. The porites resemble astræans, but the pits
are smaller, with fewer partitions, and the substance is more porous.
Above these and capping the reefs are the beautiful branching and
palmate madreporians, together with millepores, numerous varieties of
sea-fans (/Gorgonacea/), and the calcareous seaweeds (nullipores),
making a garden of beautiful branching forms of every shape and color.
The coral reef is as thickly inhabited by other living organisms
as is the forest by birds and insects. Mollusks, worms, crabs,
starfishes, and sea-urchins find resting-places there and work
destruction to the coral masses, as they bore and penetrate the reef
in various ways until large fragments of it are detached and either
washed by the waves to places far from their foundation, or ground
to sand, which, filling the interstices of the reef, adds to its
solidity.
The living coral is quite different in appearance from the bleached
skeletons commonly seen. The surface of the corallum is often soft
and downy, from the numerous waving tentacles, and its coloring is
vivid and varied. The madrepores are pink, yellow, green, brown, and
purple. /Tubipora/, the organ-pipe coral, has green polyps emanating
from its red tubes. White polyps in star-like form dot the branches
of the red coral of commerce, /Corallina rubrum/. The whole mass
of /Helipora/ is bright blue, [pg148] and the beautiful sea-pens
are both highly colored and phosphorescent. Owing to the fact that
these brilliantly colored polyps were mistaken for blossoms, the
recognition of their true character was long delayed, they having
been ranked as vegetables until comparatively recent times.
With few exceptions, corals do not grow in water below the
temperature of 68°, hence they are inhabitants of tropical and
subtropical waters. The Florida Keys are coral reefs, and the species
described below are to be found there.
GENUS ^Oculina^
Arborescent; corallites arranged somewhat spirally on branches and
widely separated; branches compact between corallites. Each bud is
for a time at the apex of the branch, but finally becomes lateral,
and then gives off another bud from its upper surface, and so the
stem lengthens. (Plate XLIV.)
GENUS ^Astræa^
The star-corals. The corals of this genus are hemispherical masses
covered with small star-shaped pits, or corallites. Although the
diameter of an astræa-dome may be twelve feet or more, it has only
one half or three quarters of an inch of living coral on its surface,
the rest being solid matter left behind as the polyps rose in growth.
The colony increases by self-division. The septa meet in the center
of the corallite, making star-like pits; the surface is comparatively
smooth. (Plate XLIV.)
Genera ^Meandrina^, ^Diploria^
Corallum massive, hemispherical in shape, with furrows running in
irregular lines over the whole surface. The peculiar serpentine form
of the corallite is produced by the animal growing in one direction,
fission being incomplete, and new mouths being successively opened
until a line of them extends along a common stomach.
^D. cerebriformis.^ This species is commonly known as brain-coral
or brain-stone. The hemispherical shape, together with the peculiar
serpentine corallites, makes its resemblance to the human brain
very noticeable and the name unusually appropriate. This species,
when living, is bright yellow. (Plate XLV.)
[Illustration: PLATE XLIV. Millepora alcicornis. Lucernaria auricula.
Cassiopeia frondosa. Astræa argus. Oculina.]
[Illustration: PLATE XLV. Porites furcata and P. astræaoides. Diplora
cerebriformis. Madrepora cervicornis. Madrepora palmata. Mycedium
fragile.]
GENUS ^Madrepora^
Some species of these corals appear like branches, while others
have flat, low surfaces or fronds; all of them are covered with
innumerable small cylindrical cups. Each cup is the home of a polyp,
which secretes calcareous matter around its column, and septa between
its radial partitions. The corallum, when examined with a glass,
looks like meshwork. Through the fine openings of the porous surface,
the polyps of the colony are connected by interlacing tubes of animal
substance (cœnosarc). The polyps of the madrepore colonies are
small in comparison with the connecting structure, which becomes very
massive; but, although large, the corallum is fragile, on account of
its perforated character and the exceeding delicacy of its parts.
In species which form incrustations, new polyps arise from tissue
which spreads beyond the corallites. In some species certain polyps
and corallites increase in length, growing longitudinally, and
continually form buds around the base. This manner of growth leads
to the formation of branches, while the former manner gives lateral
extension. Both of these forms of budding may take place at the same
time in the same colony. The madrepores are among the most common of
the reef-builders. They form reefs which extend for miles around the
Florida Keys.
^M. cervicornis^, the stag-horn coral. This is a branching species
which attains large size. Its manner of growth is as follows: At
the tip of each branch is an individual polyp, which is larger
than those which surround the branch. This is the original animal
which started the branch, and is the parent from which all the
others on the branch have budded. The large terminal polyp buds
around the base; a surplus of lime also collects at the base and
clogs its tissues, so that it no longer can perform the functions
of life, and after a certain period the base becomes dead matter.
The polyp on the upper end continues to live and rises above the
excess of solid matter. At the same time it continues to form new
buds. The buds become independent corallites and secrete an excess
of calcareous matter at their bases, which cements them to the
parent stock and increases the thickness of the branch. Thus, as
the original polyp constantly rises and buds, the colony assumes a
stem-like form, covered with numerous individuals. Certain polyps
on the main stem have the attributes of the parent animal. These
start branches, and so the process goes on, and in time the colony
becomes much branched and arborescent in form. In the living coral
each little polyp is like a minute sea-anemone, having a colored
cylindrical body surrounded on its upper disk with numerous
tentacles. (Plate XLV.) [pg150]
^M. palmata.^ This madrepore grows like the one described above,
except that the branches do not remain separated, but unite or grow
together, giving broad, flat surfaces which resemble fronds. When
carefully examined these surfaces show striations which indicate
the course of the branches. The structures forming the lobes are
caused by the failure of the branches to unite. On the Carysfort
Reef of the Florida Keys this species covers the top of the reef
for several miles, nearly reaching the surface, and appears like a
vast bed of low yellow shrubbery. (Plate XLV.)
GENUS ^Astrangia^
^A. danaë.^ A small coral found on the New England coast. It lives
in the clefts of rocks in small patches, sometimes two to three
inches across and one quarter of an inch or more high. Frequently
it is like a thin crust of lime covered with star-like divisions.
Sometimes it forms branches. The living animals are white, and
when expanded rise above the cells and resemble a cluster of small
sea-anemones.
SUBCLASS =ALCYONARIA= or =HALCYONOIDA=
[Illustration: /Alcyonium palmatum/: /A/, entire colony; /B/,
spicules.]
In this subclass—the actinoid corals—the polyps are of two kinds.
The smaller are without tentacles and are called /siphonozoöids/. The
larger have but eight radial partitions and eight tentacles. This
limitation of parts places them in a higher rank than the corals of
the first subclass. Another characteristic of these polyps is the
presence of symmetrical branchlets on the tentacles, which give them
a feather-like appearance. These corals are called halcyonoids.
[pg151]
Some of them may easily be fancied to have been selected for
halcyons' nests, as the name suggests—the sea-fans, for example.
ORDER =ALCYONACEA=
GENUS ^Alcyonium^
^A. palmatum.^ This coral community is found sometimes at low-water
mark, but usually in deeper water, attached to shells and stones.
It is commonly known as dead-men's-fingers, an unpleasant name
given it by fishermen because of a fancied resemblance to a human
hand with only the stumps of the fingers. The substance of the
coral is semi-cartilaginous, with scattered spicules of lime which
give it stability. When the polyps are fully extended the colony
is rather attractive in appearance, but not so when contracted.
It is found in abundance on the New England coast. An immense
/Alcyonium/, /Paragorgia arborea/, grows on the fishing-banks off
Newfoundland, and is sometimes brought up on the fishing-lines. It
is tree-like in form, and measures six feet or more in length.
GENUS ^Tubipora^
[Illustration: /Tubipora/, organ-pipe coral, natural size.]
The organ-pipe coral. This genus, which is deep red in color and very
fragile, consists of many tubes slightly separated from [pg152] one
another, but connected by horizontal platforms at short intervals.
The form of reproduction, by budding, in this colony is peculiar to
itself. The spicules of lime secreted in the polyp unite or fuse into
a tube or cylindrical skeleton. At certain stages of development
the polyp sends out a horizontal expansion, which unites with the
expansions of other polyps and becomes calcified, forming a shelf
which binds the tubes together. From the top of the platforms other
corallites are formed, and thus a colony is made, which broadens as
it rises in its growth. The body of the polyp is green, the skeleton
red. It belongs to the East Indian seas and is given here only as an
example of a peculiar manner of growth.
ORDER =GORGONACEA=
SEA-FANS, SEA-WHIPS, AND SEA-FEATHERS
These are compound, tree-like /Alcyonaria/, with a calcareous or
horny skeleton which forms a branched axis and is covered with a
layer of united polyps having spicules of lime distributed through
the mass, which give some firmness to the bark-like covering.
Gorgonias, in great variety, grow in abundance on the coral reefs and
mud-flats of Florida, forming masses of low shrubbery, pink, yellow,
brown, or purple in color.
The sea-whips and sea-feathers are varieties of gorgonias, which are
named from their forms. Some have shapes which resemble branching
shrubs; others are long unbranched rods, either straight or spiral.
They attain a height of several feet and are of various colors. The
colony has a horny axis surrounded by a living mass which resembles a
sheet of animal matter. This mass consists of polyps closely united,
and has throughout its substance spicules of carbonate of lime,
making it a kind of calcareous crust or bark. In dried specimens
this becomes very brittle, and is easily broken from the horny axis.
(Plates XLVI, XLVII.)
[Illustration: PLATE XLVI. GORGONIAS.
Eugorgia aurantica. Muricea specifera. Pterogorgia acerosa. Gorgonia
anceps.]
[Illustration: PLATE XLVII. Leptogorgia rigida (a gorgonia). Eunicea
lugubris (a gorgonia). Gorgonia flabellum (a gorgonia). Leptogorgia
Agassizii (a gorgonia). Pennatula borealis and P. aculeata
(sea-pens).]
The sea-fans are colonies with a central, horny, flexible, and
much-branched axis, covered, as in the sea-whips, with a layer of
united polyps containing spicules of lime, which make a somewhat
[pg153] firm crust. This, in dried specimens, breaks off readily.
The colony branches profusely, or rather separates by fission, in
one plane, the large and small branches making a network of fan-like
shape and often of great fineness and intricacy. These fans attain a
length of several feet and a corresponding breadth, and are abundant
in semi-tropical as well as in more southern waters. In color they
are red, yellow, brown, or purple.
ORDER =PENNATULACEA=
SEA-PENS
These singular colonies resemble quill-feathers, such as are used for
pens, and are named for this reason. The long, horny central axis is
naked below, and is partly buried in the sand, but is not permanently
attached. The upper portion of the axis has two rows of short,
opposite, lateral branches; on the upper side of the branches the
polyps live in separate inclosures. Spicules of lime are present in
the substance of the branches, which gives them stability. Sea-pens
are found at moderate depths and are widely distributed. They are
highly colored and phosphorescent. [pg154]
TABLE SHOWING THE CLASSIFICATION OF THE CTENOPHORA DESCRIBED IN THIS
CHAPTER
Class =CTENOPHORA=
Order =CYDIPPIDA= (/Two tentacles, retractile into sheaths/)
Genera Species
^Pleurobrachia^ ^P. rhododactyla^
Order =LOBATA= (/Numerous lateral tentacles contained in a groove;
body compressed; two large oral lobes/)
^Bolina^ ^B. alata^
^B. septentrionalis^
^B. vitrea^
^Mnemiopsis^ ^M. Leidyii^
Order =CESTIDA= (/Ribbon-like form, from body being extremely
compressed in the vertical plane/)
^Cestum^ ^C. veneris^
Order =BEROÏDA= (/No tentacles; mouth very wide; gullet occupies
greater part of body/)
^Idyia^ ^I. roseola^
^I. cyanthina^
[pg155]
CLASS =CTENOPHORA=
COMB-JELLIES
These are delicate, free-swimming, generally spherical bodies,
resembling jellyfishes in outline, transparency, and gelatinous
consistency, but differing from them widely in the manner of
locomotion. They are called "comb-jellies" from the rows of flat
cilia, arranged like the teeth of a comb, which run in eight
meridional lines over the surface. It is by means of these cilia
that the animal moves through the water. The little paddles are
worked in unison, in single lines, or each one of them can be
moved independently, and they give the animal varying and peculiar
motions. The /Ctenophora/ are nearly transparent, but have a
prismatic coloring, caused by the waving cilia, and at night they are
phosphorescent. They are widely distributed, being found in all seas.
The mouth of the animal opens into a gullet which extends two thirds
through the length of the body. On each side of the gullet is a
vertical tube. The two tubes unite at the base of the gullet, and
from there run as a single canal to the end opposite the mouth, and
open to the outside through two excretory pores. From the base of
the gullet, where the tubes unite, two other tubes extend laterally,
which divide and subdivide in a horizontal plane, becoming eight in
number, and connect at the surface with the lines of cilia; then,
dividing, run in opposite directions to the poles of the spherical
body. The animal derives its nourishment and air through this
circulatory system. A nervous system is situated at the pole opposite
the mouth, in a small area surrounded by cilia, in the center is an
eye-speck, or lithocyst. [pg156]
ORDER =CYDIPPIDA=
GENUS ^Pleurobrachia^
[Illustration: /Pleurobrachia rhododactyla/, in motion.]
^P. rhododactyla.^ A transparent spherical body, one inch to one
and a half inches in diameter, with eight combs or plates of flat
cilia extending from pole to pole. At one pole is the mouth, like
a slit, at the other a small area in the center of which is an
eye-spot. From the body hang two tentacles, half a yard or more
in length, fringed with cilia. The tentacles are very contractile
and can be rolled up or expanded with great rapidity; they take
graceful curves as the animal moves rapidly through the water.
/Pleurobrachia/ has a pink tint, and prismatic colors play over
it from the vibrating cilia. It is a beautiful and interesting
creature to watch. Found along the shores of Massachusetts and
Maine.
ORDER =LOBATA=
GENUS ^Bolina^
[Illustration: /Bolina alata/, seen from the broad side: /o/,
eye-speck; /m/, mouth; /r/, auricles; /v/, digestive cavity; /g/,
/h/, short rows of flappers; /a/, /f/, long rows of flappers; /b/,
/n/, /x/, /t/, /z/, tubes winding in the larger lobes; /i/, base of
gullet. About half natural size.]
^B. alata.^ Slightly oval in form; lower part of the body divided
into two large lobes which hang below the mouth. Four of the
swimming-plates are shorter than the other four and terminate in
curious processes or short appendages called auricles. /Bolina/
is about two inches in length, and is very delicate, transparent,
and phosphorescent. Its contractile power enables it to vary in
outline to a considerable extent. It has a slow undulating motion,
and sometimes carries its lobes uppermost and open. Usually found
associated with /Pleurobrachia/ from Massachusetts northward.
^B. septentrionalis.^ Found on the northern Pacific coast.
^B. vitrea.^ A species found in Florida. [pg157]
GENUS ^Mnemiopsis^
^M. Leidyii.^ Resembles /Bolina/ in general form; often six to
eight inches in length; gregarious, thousands often being collected
together; exceedingly phosphorescent.
ORDER =CESTIDA=
GENUS ^Cestum^
^C. veneris^, Venus's girdle. This singular animal, although not
an inhabitant of our seas, has its place in this group, and is
shown here because of its very curious shape. In form it is flat
and ribbon-like. Sometimes it attains a length of five feet, while
in breadth it is but one or two inches. The mouth is midway in its
length and is opposite the sense-organ or eye-spot. On each side of
the mouth is a short tentacle which protrudes from a sac. Four of
the swimming-plates are small; the other four extend along the edge
of the body. /Cestum/ moves by contractions of the body more than
by the combs which fringe its edges. It is very transparent, with
a violet hue, and is so delicate that it is difficult to capture
it uninjured. Its habitat is the Mediterranean Sea. It may be seen
among the zoölogical specimens in almost any museum.
[Illustration: /Cestum veneris./]
ORDER =BEROÏDA=
GENUS ^Idyia^
^I. roseola.^ This species has an ovate body three to four inches
in height and about half as broad. Some individuals are larger.
It has [pg158] an eye-spot on the upper rounded side, and at
the other end a very large mouth opening into a digestive cavity,
which occupies the greater part of the body. A delicate fringe
surrounds the area about the eye-spot, and eight rows of cilia
run from there to the oral end. It has no tentacles. /Idyia/ is
pink and especially highly colored at the spawning-time. Like
other jellyfishes, their part in life is finished when they have
discharged their spawn, and the first September storms break them
to pieces. In July and August they are plentiful on the New England
coast. They appear at the surface of the water in the hottest part
of the day, but disappear entirely when the water is in the least
rough or the weather is cold or the sun overcast. Their movements
are slow and graceful, the long axis being carried in a nearly
horizontal position. They are exceedingly voracious, feeding
chiefly on other /Ctenophora/, and often swallowing animals as
large as themselves.
[Illustration: /Idyia roseola/, half natural size: /d/, /e/, /f/,
/g/, /h/, rows of locomotive flappers.]
^I. cyanthina.^ This species, found on the northern Pacific coast,
broadens near the center, making it somewhat vase-shaped. /Idyopsis
Clarkii/, a similar genus, found in Florida, is globular. All these
species are very beautiful, the rapid movement of the cilia giving
them a brilliant iridescence.
III
WORMS
(PLATYHELMINTHES
NEMATHELMINTHES
ANNULATA)
TABLE SHOWING THE CLASSIFICATION OF THE WORMS DESCRIBED IN THIS
CHAPTER
Phylum =PLATYHELMINTHES=
Class =TURBELLARIA=
Order ~POLYCLADIDA~
Genera Species
^Planocera^ ^P. nebulosa^
^Stylochopsis^ ^S. littoralis^
^Leptoplana^ ^L. folium^
Order ~TRICLADIDA~
^Planaria^ ^P. grisea^
^Procerodes^ ^P. frequens^
^Bdelloura^ ^B. rustica^
^B. candida^
^Fovia^ ^F. Warrenii^
Order ~RHABDOCŒLIDA~
Class =TREMATODA= (/External and internal parasites/)
Class =CESTODA= (/Internal parasites/)
Class =NEMERTINEA=
^Tetrastemma^ ^T. arenicola^
^Nemertes^ ^N. socialis^
^N. viridis^
^Meckelia^ ^M. ingens^
^M. rosea^
^Cerebratulus^ ^C. angulatus^
^Cosmocephala^ ^C. ochracea^
^Polina^ ^P. glutinosa^
Phylum =NEMATHELMINTHES=
Class =NEMATODA=
^Pontonema^ ^P. marinum^
Phylum =ANNULATA=
Class =CHÆTOPODA=
Subclass =Polychæta=
Order ~ERRANTIA~
Families Genera Species
~SYLLIDÆ~
~APHRODITIDÆ~ ^Polynoë^ ^P. squamata^
^P. sublevis^
^Harmothoë^ ^H. imbricata^
^Aphrodite^ ^A. aculeata^
~PHYLLODOCIDÆ~ ^Phyllodoce^ ^P. gracilis^
~NEREIDÆ~ ^Nereis^ ^N. virens^
^N. pelagica^
^N. limbata^
~NEPHTHYDIDÆ~ ^Nephthys^ ^N. ingens^
^N. picta^
~EUNICIDÆ~ ^Marphysa^ ^M. sanguinea^
^Diopatra^ ^D. cuprea^
^Arabella^ ^A. opalina^
^Lumbriconereis^ ^L. tenuis^
~GLYCERIDÆ~ ^Glycera^ ^G. americana^
^G. dibranchiata^
Order ~SEDENTARIA~ or ~TUBICOLA~
Families Genera Species
~SPIONIDÆ~ ^Nerine^ ^N. agilis^
^N. coniocephala^
~CIRRATULIDÆ~ ^Cirratulus^ ^C. grandis^
~TEREBELLIDÆ~ ^Thelepsus^ ^T. cincinnatus^
^Amphitrite^ ^A. ornata^
^Polycirrus^ ^P. eximius^
^Chœtobranchus^ ^C. sanguineus^
~AMPHICTENIDÆ~ ^Cistenides^ ^C. Gouldii^
~MALDANIDÆ~ ^Clymenella^ ^C. torquata^
^Maldane^ ^M. elongata^
~ARENICOLIDÆ~ ^Arenicola^ ^A. marina^
~SABELLIDÆ~ ^Sabella^ ^S. microphthalma^
~SERPULIDÆ~ ^Serpula^ ^S. dianthus^
^Spirorbis^ ^S. borealis^
Subclass =Oligochæta= (/Mostly terrestrial or fresh-water
forms/)
Class =GEPHYREA=
Order =SIPUNCULOIDEA=
Genera Species
^Sipunculus^ ^S. nudus^
^Phascolosoma^ ^P. Gouldii^
Class =HIRUDINEA= (/Leeches/)
[pg163]
WORMS
Burrowing in sand and mud, lying under stones and in crevices of
rocks, concealed in various kinds of tubular cases which are free or
attached to stones or shells, crawling over the ground or seaweeds,
swimming free or attached to other animals, is found in abundance a
class of animals commonly known as "worms," and generally regarded as
repulsive creatures unworthy of attention.
To the biologist, however, worms are among the most interesting forms
of lower animal life. The amateur collector, if he stops to give
them careful consideration, will probably find them unexpectedly
interesting, and will be surprised to find how many varieties of them
there are, and how different they are from his preconceived notion of
them. Worms are varied in structure, their habits are strange, and
their form and color often beautiful. Although plentiful, they are
not conspicuous, but are easily found if search is made for them, and
so large a class of shore animals should not be passed by unnoticed.
Unusual biological interest is attached to this group because, in the
different types, affinities with other classes of animals are found,
suggesting, perhaps, connecting-links with higher organizations.
They are the first animals to show definite bilateral symmetry, or
two similar sides, and to carry the same part of the body always in
front. Formerly one division, called /Vermes/, comprised all the
worms. To-day they are separated into four divisions, or phyla. The
most careless observer easily recognizes the basis of separation, for
the flatworms, the round- or threadworms, the wheel-like animalcules,
and the jointed worms have very obvious differences. The names given
the phyla express these distinctions, the termination [pg164]
meaning "worm"; the prefixes /Platy-/, /Nemat-/, /Troc-/, meaning
"flat," "thread," "wheel," respectively; while /Annulata/, meaning
"ringed," describes the segmented forms belonging to that phylum.
There are vast numbers of parasitic worms, which live internally or
externally on their hosts, there being no animal of land or sea, of
high or low degree, which is not subject to the affliction of these
visitors. The parasitic worms are degenerate, some being without
digestive organs, or without eyes, or without locomotor organs, and
so on, as the case may be, the host supplying the missing function.
The life-history of these low forms is interesting; but parasitic
worms do not come within the scope of this book, and are mentioned
only to mark their place in the series.
PHYLUM =PLATYHELMINTHES=
FLATWORMS
The flatworms have a flattened body, more or less compressed in the
different classes. Ordinarily the body is very thin, and, when short,
has a leaf-like form; when long it is ribbon-like. Some species are
thick in the middle and thin at the edges. They have a dorsal, or
upper, and a ventral, or under, surface; a right and a left side; an
anterior and a posterior end. The anterior end is carried forward and
has some of the characteristics of a head, though a distinct head is
not apparent. The mouth is on the ventral surface. In some species it
is in the middle of the length of the body; in others it is before or
behind this point.
The flatworms are the first animals to assume pronounced bilateral
symmetry. They are soft-bodied, having no supporting skeleton, and
they have no segments, or divisions, such as are found in higher
types, as in /Annulata/. They have no body-cavity, the space
between the organs and the body-wall being filled with tissue. The
alimentary canal has no anal aperture, the excretions being carried
off by a water-vascular system consisting of branching vessels which
end in minute bundles of vibrating cilia, called ciliary flames.
These flames communicate with the exterior through small pores or
flame-cells. Their sense-organs are eyes [pg165] and otocysts. The
latter are sacs containing crystals of carbonate of lime, and their
function is supposed to be that of hearing.
The flatworms are hermaphroditic, and their propagation is by means
of eggs. They are numerous and very generally distributed, occurring
in fresh and salt water, on land and shore, on the surface and in
the depths of the sea. A vast number also are parasites and infest,
internally or externally, nearly every living creature. The parasitic
forms differ anatomically from the free-living worms. The internal
parasites, living by absorption of the digested food of their hosts,
have no digestive organs; they are also devoid of organs of sense
and of defense. The external parasites, being carried about by their
hosts, are without organs of locomotion.
CLASS =TURBELLARIA=
The turbellarians are the simplest group of bilateral animals and
occupy the lowest place among worms. They owe their name to the fact
that they are covered with cilia, which are constantly in motion and
cause a slight turbulence in the water around them.
ORDER =POLYCLADIDA=
("/Many-branched/")
The polyclads are found below half-tide mark on the under side of
stones and on seaweeds. Sometimes they are found swimming about
at night. They are leaf-like in form, one inch to two inches in
length, and are very thin and delicate. They adapt themselves to the
inequalities of the surfaces to which they attach themselves, and
often are of the same color, and therefore are so inconspicuous that
they are apt to escape notice. They move with a gliding motion over
surfaces, and often swim when in search of food.
The intestine is much branched and has no anal aperture. From the
mouth, which is placed in the center of the ventral surface, a
pharynx, or muscular fold, is protruded in some species, which
enables the worm to attach itself to and consume prey of considerable
size. After digestion has taken place, the fecal [pg166] matter
collects in the main intestine and is forcibly ejected by the
pharynx. Numerous eyes are collected in groups on the anterior dorsal
surface, or arranged around the margin of the body. The eggs are laid
in shell-like cases, and cemented together in plate-like masses or in
spirals, and attached to shells or stones. (Plate XLVIII.)
GENUS ^Planocera^
^P. nebulosa.^ One half of an inch wide and three quarters of an
inch long, circular or elliptical in shape; very flat and thin;
olive-green on the dorsal surface, with a line of darker color on
the posterior end, and whitish retractile tentacles on the back.
Found creeping on under side of stones in tide-pools.
GENUS ^Stylochopsis^
^S. littoralis.^ About one half of an inch long; changeable in
form, from broad oval to elliptical; color pale green, veined with
a lighter shade on the dorsal side, flesh-colored on the ventral
surface; numerous eyes arranged in irregular rows near the margin
and in groups in front of the tentacles, also clusters of eyes on
the tentacles. Found under stones between tide-marks.
GENUS ^Leptoplana^
^L. folium.^ Body flat; margin thin and undulated; shape leaf-like,
but changeable; about one inch long and one half of an inch wide;
color pale yellow, veined with a deeper shade; eyes in four groups
near the anterior end.
ORDER =TRICLADIDA=
("/Three-branched/")
The triclads are divided into three groups: those of the fresh-water
ponds and streams, those of the land and sea, known as planarians,
and those of the sea. The planarians are the most interesting worms
in the order. The triclads differ from the polyclads in being
elongate in form and in having the intestine in three branches
instead of in many. The mouth is midway in the length of the body,
on the ventral side, and from it protrudes a pharynx, which is
cylindrical or bell-shaped, and is capable of great dilatation. With
the pharynx the worm, which is wholly carnivorous, envelops other
worms, crustaceans, or any animal food. Several species are found on
the under side of stones in tide-pools.
[Illustration: PLATE XLVIII. Polyclad worm. Worm-tubes of Diopatra.]
GENUS ^Planaria^
^P. grisea.^ Oval or elliptical in form; anterior end truncate;
posterior end rounded; color yellow or gray, with a light stripe;
two black eyes surrounded with white; length one half to three
quarters of an inch; width about one eighth of an inch. Found under
stones between tide-marks.
GENUS ^Procerodes^
^P. frequens.^ One eighth of an inch long; brown or black above,
gray below; has two kidney-shaped eyes; active and abundant. Found
under stones near high-water mark.
GENUS ^Bdelloura^
^B. rustica.^ Body milk-white, smooth, thin. Found on /Ulva
latissima/ (sea-lettuce).
^B. candida.^ Parasitic on the gills of the horseshoe-crab.
GENUS ^Fovia^
^F. Warrenii.^ Bright red, narrow, oblong. Found on eel-grass.
ORDER =RHABDOCŒLIDA=
Minute, active worms found among the red seaweeds. They are brown in
color, and are marked by one or more transverse white bars.
CLASS =NEMERTINEA=
The nemerteans are long, narrow, flat, smooth worms, and vary from
one half of an inch to many feet in length. They are exceedingly
contractile, and when alarmed can shrink to less than half their
normal length. They are very generally distributed, and are to be
found between tide-marks, in loose coils like a string, under stones
on sandy and muddy shores. The very long species, like /Lineus
marinus/, are solitary, but other smaller species are gregarious,
many worms being coiled together in tangled masses. Some species are
to be found in empty shells, and others live among the seaweeds. They
are very slimy, the epidermis secreting an abundance of mucus, and
they can often be tracked by the trail of slime they leave behind
them. This mucus sometimes hardens, forming for some species a
tubular [pg168] covering; others remain naked. All are covered with
vibrating cilia, which is a universal feature of flatworms. In color
they may be white, yellow, green, red, purple, etc., and sometimes
they are banded or striped with a contrasting color. The ventral is
usually lighter than the dorsal surface.
The principal characteristic of the nemertean worms is a long
thread-like organ, known as the /proboscis/. This lies in a sheath
along the center of the dorsal surface, and is quickly thrown out
to a great length, and as quickly completely withdrawn within the
body. The proboscis is slender, hollow, muscular, and full of nerves.
It reaches the outside through a pore at the anterior end of the
body, and has no connection with the alimentary system. It is used
as a feeler and as a weapon. Some species have a sharp spine at the
end of the proboscis, others have stinging-cells. The proboscis is
sometimes so forcibly ejected that it breaks off, in which case it
retains its vitality for some time, and seems as if it were itself a
worm. A new proboscis is quickly grown by the worm to take the place
of a lost one. The head is a little broader than the body, and has
eyes arranged in one or several pairs on each side. The mouth is on
the ventral surface, near the anterior end, has thick lips, and is
very dilatable. Through the mouth the animal ejects a part of the
esophagus and envelops its prey, which is often of considerable size.
Chætopod worms they often swallow whole; the soft parts, after being
digested, are carried off through the regular passages, ending in the
ciliary flames (page 164), while the indigestible parts are ejected
at the anus. Often the spines and bristles find their way out by
perforating the intestine and the body-wall, without apparently doing
the worm any injury. The perforated parts quickly heal.
These worms have the strange power of regenerating lost parts;
mutilated portions are soon repaired. The anterior end, when severed
from the rest of the body, grows again into a complete individual,
while the posterior end continues to perform part of its functions
and retains its vitality for a considerable time before dying. One
species, /Lineus sanguineus/, is capable, after being broken in
pieces, of regenerating each section into a perfect worm. [pg169]
The nemerteans are carnivorous, voracious, and often cannibalistic.
They will live for some time in confinement, losing, however, their
bright color, and the smaller worms will gradually disappear, as they
are devoured by the larger ones. The mode of locomotion varies with
the order. Some species attach their long proboscis to a distant
object, then drag the body to it; some glide rapidly along by means
of the muscles of the body and the cilia which cover it; others swim.
The swimming forms have thin edges which have a wave-like motion,
and this, together with a lateral movement of the tail, propels them
through the water. In some species the worm develops directly from
the egg; others pass through a larval stage before reaching maturity.
GENUS ^Tetrastemma^
^T. arenicola.^ Dark flesh-color or purplish; slender, cylindrical,
four to five inches long when extended; head changeable in form and
partly distinct from body because of slight constriction at the
neck. It lives in sand at low-water mark.
GENUS ^Nemertes^
^N. socialis.^ Individuals very slender, five to six inches long
when extended; color brown or black, a little lighter underneath;
three or four eyes in lines on each side the head. It is abundant
under stones on rocky shores, many coiled together, forming large
masses.
^N. viridis.^ Color olive-green or brown, crossed by faint pale
lines; body changeable in form; when extended, six to eight inches
long, one eighth of an inch or less in breadth; row of dark eyes on
each side of flat head. Common under stones between tide-marks on
northern rocky shores.
GENUS ^Meckelia^
^M. ingens.^ One of the largest nemertean worms; found on sandy and
muddy shores near low-water mark. The young, from several inches to
a foot long, are common. When full-grown some attain the length of
twelve or thirteen feet, and are an inch in breadth and quite flat
when extended, but can contract to two or three feet in length,
and are then nearly cylindrical. This worm, although so soft,
penetrates the sand with great rapidity. Its head changes shape
constantly and assists the proboscis when burrowing. It is also
able to swim. Its color is yellowish or flesh-color, with whitish
edges and a central band.
^M. rosea.^ The largest specimens are six to eight inches long and
one quarter of an inch broad; lives in burrows on sandy beaches;
color red or pink; often covered with sand, which adheres to the
mucus which the worm secretes. [pg170]
GENUS ^Cerebratulus^
^C. angulatus.^ Olive-green, with light dorsal stripe.
GENUS ^Cosmocephala^
^C. ochracea.^ Two to three inches long when extended; gray or
yellowish-white, and mottled by the internal organs showing through
the translucent body; line of lighter color down the back; anterior
end often orange-colored. It is common near low-water mark under
stones and in the dead tubes of /Serpula/.
GENUS ^Polina^
^P. glutinosa.^ One to two inches long; color orange or light
yellow, with a faint line of deeper color down the center of the
dorsal surface; very slimy; eyes numerous, in oblique lines on the
head. Found in tide-pools on algæ.
PHYLUM =NEMATHELMINTHES=
ROUNDWORMS
The worms of this phylum have the general name of roundworms, which
distinguishes them from the flatworms of the preceding division and
from the segmented worms of the /Annulata/. The body is elongated,
cylindrical, smooth, and pointed at both ends. With few exceptions,
they are parasitic.
A few of the nematode species are free, living under stones and among
seaweeds at about low-water mark.
CLASS =NEMATODA=
GENUS ^Pontonema^
^P. marinum.^ Slender, white, smooth, active, cylindrical;
constantly coiling and uncoiling itself.
PHYLUM =ANNULATA=
SEGMENTED WORMS
The name of this phylum expresses the principal characteristic of
the group of worms which have elongated bodies composed of series
of short parts, or ring-like divisions. Each one of these segments
contains a separate and similar set of internal organs. [pg171]
The annelids are divided into four classes, one of which, the
/Gephyrea/, has not the characteristics which distinguish the group.
The classes are easily recognized by conspicuous features. Some have
bristles; others have scales; others have tentacles around the head
and inclose themselves in tubes. Many are highly colored, and all
are of great interest to the naturalist from the diversity of their
habits, form, and structure, and from the analogies they bear to
other and higher types of animals.
The annelids are the highest type of worms, their organs having
attained more special functions. The sense-organs of eye and ear
are more developed, and the nervous system has distinct centers,
or ganglia, the first and largest ganglion being a part of the
head. They are found in abundance everywhere. Some species grow to
the length of one foot or two feet. Some are carnivorous, others
vegetarian, and many are mud-eaters, swallowing sand and mud for the
sake of the organisms they contain. They themselves are food for
fishes, which devour them in vast quantities, rooting them out of
their burrows or capturing them at night, at which time they swim
about.
CLASS =CHÆTOPODA=
("/Bristle-footed/")
[Illustration: A magnified parapodium of /Nereis dumerilii/: /dors.
cirr./, dorsal cirrus; /vent. cirr./, ventral cirrus; /s/, setæ.]
The bristle-worms. This class of worms has bunches of bristles on
both sides of each segment of the body, which serve as organs of
locomotion, or bristle-feet. The bristles emanate from outgrowths
of the body known as /parapodia/, which are practically limbs. The
parapodia are sometimes divided into distinct lobes or branches. The
bristles are of various shapes and often of brilliant color. They
are usually horny, sometimes simple, sometimes divided into joints,
and vary in shape in different genera. The parapodia have, besides
the bristles, a second set of [pg172] hair-like appendages, called
/cirri/. These are sense-organs and also have a respiratory function.
The cirri too vary in shape in different genera. Generally they are
hair-like, but sometimes conical; again they are broadened into
scales, as in the /Aphroditidæ/.
The body-cavity in chætopod worms is divided into a series of
chambers or segments. These divisions seem on the exterior like
constrictions, and give the body the appearance of a series of rings.
The internal organs are repeated in each segment, so that each of
the latter contains a portion of the alimentary canal, a pair of
/nephridia/, a pair of nerve-ganglia, and blood-vessels which connect
the main blood-vessels running along the dorsal and ventral surfaces.
The alimentary canal runs through the body, but is constricted at
each joint. The nephridia are curved tubes, which are excretory
organs, opening to the outside and carrying off the waste products
which have passed into the fluid of the body-cavity.
The chætopod worms have a well-developed nervous system, beginning
with a two-lobed ganglion forming a brain and head, then extending
through the worm in a double ventral chain and series of ganglia.
They have also a blood-vascular system. The blood is either colored
or colorless. Sometimes it is a bright red or green, and is often
visible through the body-wall. The circulation is effected, not
by means of a heart, but by wave-like (peristaltic) contractions
of the dorsal blood-vessel. The body is cylindrical, but in many
cases is somewhat flattened. There are two layers of muscles, one
of which encircles the body, while the other extends parallel with
its length. Respiration is effected by /gills/, which may be simple,
hair-like appendages to the parapodia, or branched, or comb-like
in form. Sometimes they are confined to the middle segments, as
in /Arenicola/; sometimes to the segments near the head, as in
/Tubicola/; or they may be extended over the whole dorsal surface.
SUBCLASS =POLYCHÆTA=
("/Many-bristled/")
The polychæte worms have one or two well-developed parapodia, or
limbs, on each side of every segment of the body, and on each
[pg173] parapodium is a bunch of bristles, or /chætæ/. There are
hundreds of species of this class of worms, the species being based
on the shape and the lobes of the parapodia, the relative length of
the cirri, the form and arrangement of the chætæ, and so on. They
are abundant on the shore everywhere, but abound where rocks and
stones afford them some shelter. Many burrow in the sand and mud.
In doing this the worm eats his way into the hole, swallowing the
mud and sand. He assimilates the organic or vegetable matter the
mud contains, and ejects the rest in cylindrical coils, known as
castings, which lie in heaps at the mouth of the burrow. By these
castings they may be traced. Others secrete tubes.
The polychæte worms are divided into /Errantia/, which are wandering,
free-swimming forms, and /Sedentaria/ or /Tubicola/, which live in
tubes permanently. These distinctions are not strictly correct, since
some species of errant polychætes form tubes (/Eunicidæ/), and some
/Sedentaria/ form no tubes.
Many polychætes are beautifully colored, some in vivid reds and
greens, with various markings; some are iridescent; some are
phosphorescent.
ORDER =ERRANTIA=
Carnivorous, free /Polychæta/, with protrusible pharynx armed with a
horny jaw. "They are active, fierce beasts of prey."
FAMILY ~SYLLIDÆ~
This family is the highest in organization of the worms. They are
small, the majority being less than an inch in length, and many are
minute. They are often highly colored. Many have long cirri on the
feet; some have alternation of generation. They are common everywhere
along the coast, but are not seen unless searched for. Sponges
sometimes are alive with them. They are interesting subjects for
microscopic study.
FAMILY ~APHRODITIDÆ~
The scale-bearing annelids. This family of worms is distinguished
from all others by having scales on the back. The scales, called
/elytra/, are flattened dorsal cirri carried on the upper parapodia,
[pg174] and generally on alternate segments and in a double row down
the back. The elytra are the breathing-organs, and, although of a
horny texture, are richly supplied with nerves. The worms are short
and have a large protrusible pharynx armed with a double pair of
horny jaws.
GENUS ^Polynoë^
The species of /Polynoë/ are determined by the number of scales they
bear. They have a flattened short body with nearly parallel sides.
The bristles are of a bright golden color. The proboscis is large and
has four powerful jaws at the end and a circle of papillæ at the top.
They are sluggish in movement and are found under stones and in the
crevices of rocks. When disturbed they roll themselves into a ball.
^P. squamata.^ Twelve pairs of rough scales; color sandy-brown,
speckled; one inch to one and a half inches long; the broad, oval
scales overlap and entirely cover the body and head. Some /Polynoë/
when disturbed throw off every scale. Very common north of Cape Cod.
^P. sublevis.^ Twelve pairs of smooth scales; usually grayish-brown
in color, speckled with dark spots; iridescent; last pair of scales
more slender than the others; length one and a quarter inches,
breadth about one quarter of an inch.
[Illustration: /Polynoë squamata./]
GENUS ^Harmothoë^
^H. imbricata.^ Sixteen pairs of smooth scales; variable in color;
usually gray, speckled, or striped.
GENUS ^Aphrodite^
^A. aculeata.^ This polychæte, sometimes called the sea-mouse, is
one of the most beautiful of worms. It is brightly iridescent in
color, from its setæ, which form a fur-like coating over the dorsal
surface. It has fifteen pairs of scales, but they are hidden by
the numerous setæ. These bristles cover its sides and back. Some
are coarse and nearly an inch long, with sharp points, and are
barbed near the ends. They curve over the back like the quills of a
porcupine. The body is three to six inches long. It is broadest in
the middle and tapers to a point. They live in mud below tide-mark,
and may be found washed upon the beach after storms. [pg175]
FAMILY ~PHYLLODOCIDÆ~
[Illustration: /Aphrodite aculeata/, natural size: /c/, neuropodial
chætæ; /p/, palps; 1, iridescent bristles; 2, stiff chætæ; 3, felting
bristles of notopodium.]
These animals are commonly known as "paddle-worms," on account of
having leaf-like cirri, which they use in locomotion. The head is
long and bears four pairs of short and four pairs of long tentacles.
The body is long and depressed, sometimes two feet in length, usually
eight to twelve inches long. The general color is bright green and
iridescent. Found in tide-pools. Specimens are often found by digging
in sandy mud, or they may be obtained by placing old shells and other
material in a dish of sea-water. When the water becomes a little
stale, the worms of this and other families make their way to the
sides of the dish, where they secrete a colorless slime which holds
mud or any light matter that it may come in contact with. In this
condition, when lifted or disturbed, they crawl rapidly out of the
slime, and show to good advantage their elongate body, which is often
beautifully colored.
GENUS ^Phyllodoce^
[Illustration: /Phyllodoce paretii./]
^P. gracilis.^ Three inches or more long and one sixteenth of
an inch wide; large proboscis, with twelve longitudinal rows of
prominent [pg176] projections on the swollen base, its terminal
end smooth, with a circle of round projections at the orifice;
color green, with a row of dark spots down the center of the dorsal
surface and a fainter line of spots on each side at the base of the
parapodia. Found on the New England coast.
FAMILY ~NEREIDÆ~
GENUS ^Nereis^
[Illustration: Head of /Nereis pelagica/.]
Among the most common of the polychæte worms is the genus ^Nereis^,
various species of which are found in all parts of the world. They
are abundant under stones, among seaweeds, and living in burrows
between tide-marks. They are active, fierce, and voracious. Some
attain a length of eighteen or more inches. They are commonly known
as "clam-worms," and are used by fishermen for bait. /Nereis/ has a
distinct head, consisting of two parts. One, the /prostomium/, bears
on its upper side four eyes and a pair of short, conical tentacles,
and on the lateral sides a second pair of processes called /palps/.
The palps are more conspicuous than the tentacles, and consist of two
parts, a large base and a small terminal point, the latter capable
of being withdrawn. The palps are sense-organs and perhaps test the
food. The second part of the head, or /peristomium/, bears on the
sides four pairs of long tentacles which are used as feelers. The
mouth is on the ventral side, and through it /Nereis/ throws out
its pharynx, which contains a horny, notched jaw. It seizes its
prey with this jaw, which, with the pharynx, is then withdrawn and
tears the food apart, acting like a gizzard. The body of /Nereis/
is rounded above and nearly flat below. Each of the segments has a
pair of parapodia, bearing a bundle of bristles and cirri. The last
segment of the body is elongated, cylindrical, and without parapodia,
but has on the end a pair of long cirri, which give the appearance
of a divided tail. Each segment of the body, except the head- and
tail-segments, contains a pair of excretory tubes (/nephridia/),
ganglia of nerves, and a portion of the intestine and of the vascular
system. There are circular muscles by which the worm can diminish its
diameter, longitudinal [pg177] muscles in four bands, and muscles to
move the parapodia. Breathing is carried on over the whole surface
of the body, and especially in parts of the lobes of the parapodia
called gills. Its sense-organs are eyes, palps, tentacles, and cirri.
^N. virens.^ This species is found from New York northward in
muddy and shelly sand, and under rocks between tide-marks, living
in burrows, which it lines with a mucous secretion. It is very
active, and voracious, feeding on other worms, /Crustacea/, etc.,
which it captures with its horny, protruded jaw. At night it
leaves its burrow and swims freely about like an eel, frequently
falling a prey to fishes. In color it is dull bluish-green, with
some iridescence. The gills, which are leaf-like appendages on the
parapodia, are green on the anterior end of the body and become
bright red farther back. This species, and /N. branti/ of Alaska,
are the giants of polychæte worms, often measuring eighteen inches
or more in length.
[Illustration: /Nereis pelagica./ 1, male; 2, female.]
^N. pelagica.^ Found in abundance on the New England shore and
northern coasts under stones and on shelly bottoms. The female is
four to five inches long, while the male is only two inches in
length. In this species the body is widest in the middle, while in
other species it is widest at the anterior end. The palps are long,
and the second head-piece (peristomium) is twice as long as the
next segment. The color is reddish-brown and iridescent.
[Illustration: /Nereis limbata./ Male, anterior part of body, head
and extended proboscis.]
^N. limbata.^ Five to six inches long; jaws light yellow, sharp,
and slender; parapodia and bristles smaller on the anterior than on
the posterior end; color dark brown, with light lines on the sides
and appendages, pale red on the posterior end; dorsal blood-vessel
apparent, and the heart-like pulsations can be distinctly seen.
The male worm is red in the middle section. Found along the middle
Atlantic coast on sandy shores.
FAMILY ~NEPHTHYDIDÆ~
In this family the worms have a long, thick, flattish body, a section
of which has a quadrangular form. The lobes of the parapodia are
widely separated and fringed [pg178] with membrane, appearing like
double parapodia. The pharynx is very large and projected as in
/Nereis/.
GENUS ^Nephthys^
^N. ingens.^ Sometimes six inches long and one quarter of an inch
broad; usually smaller; color whitish, with red blood-vessel
showing on dorsal side; appendages dark blown; moves actively
and burrows quickly into the mud; when captured often breaks off
a portion of the posterior end, which it is able to reproduce;
proboscis large; branchiæ between the dorsal and ventral parapodia.
Found burrowing in all kinds of mud on the New England coast.
[Illustration: /Nephthys ingens./ Anterior part of body and extended
proboscis; ventral view. Enlarged.]
^N. picta.^ More slender than /N. ingens/; color whitish, mottled
with brown on the dorsal anterior end; often a dark line down the
back; head square in front and triangular in the back. Found in
sandy mud at low-water mark.
FAMILY ~EUNICIDÆ~
These are beautiful worms, having a reddish-brown iridescent body,
with bright-red branching gills, which look like feathers, along the
back. They form parchment-like tubes.
GENUS ^Marphysa^
^M. sanguinea.^ Length six inches or more; color bronze or
brownish-red and iridescent; has bright-red branched gills and six
caudal cirri of different lengths; body flattened, except at the
anterior end, where it becomes narrow and cylindrical; has powerful
jaws. It is found under stones and in clefts of rocks at low-water
mark, or more commonly in parchment-like tubes on shelly beaches,
from Cape Cod to New Jersey.
GENUS ^Diopatra^
^D. cuprea.^ This is one of the largest and most beautiful
annelids. It is found from Cape Cod to South Carolina at low-water
mark, in sandy mud-flats, living in long tubes which project above
the surface two or three inches and are hung with seaweeds and bits
of foreign matter. /Diopatra/ is twelve inches or more in length
and one half of an inch in breadth. In color it is reddish-brown,
specked with gray, and has a brilliant whitish or opal-like
iridescence. The appendages are yellowish-brown, specked with
green. The body is flattened. From the fifth segment long, dull
to bright red, much-branched gills, resembling plumes, [pg179]
extend nearly to the end of the worm. On the ventral side of the
parapodia are whitish tubercles with a dark spot in the middle.
These papillæ secrete the long, broad tube in which the worm lives.
The worm is difficult to capture, for when pursued it retreats
quickly into its tube, which is so large that it can easily turn
around within it. (Plate XLVIII.)
[Illustration: /Diopatra cuprea./ Head and anterior part of body,
showing part of the branchiæ; side view.]
GENUS ^Arabella^
^A. opalina.^ Body cylindrical, twelve to eighteen inches long,
one quarter of an inch wide in the middle, and tapers to the ends,
which are comparatively small; lateral appendages short; color
bronze, with brilliant, opal-like iridescence; head small, conical,
but blunt and without tentacles; four eyes in transverse row at the
base of the head; segments well marked; coils into spirals when
outside of its burrow. Found in compact sandy mud at low-water mark
on the New England coast.
GENUS ^Lumbriconereis^
^L. tenuis.^ Twelve inches or more long, and slender, like a fine
cord; bright red and somewhat iridescent; very fragile. Abundant
in sandy mud on the northern New England coast, and found from New
Jersey northward.
FAMILY ~GLYCERIDÆ~
These worms are long and smooth, with numerous segments. They taper
at both ends. The head is small, conical, sharply pointed, and has
four very small tentacles. The proboscis, or [pg180] pharynx, when
protruded, is very large and long, and appears too large for the
worm. The proboscis has four hook-like jaws. These worms burrow
rapidly and disappear almost instantly into the mud or sand.
[Illustration: /Glycera meckelii/, with pharynx everted.]
GENUS ^Glycera^
^G. americana.^ Color red or purple; has branched gills on upper
side of parapodia. Found from South Carolina to Cape Cod on sandy
and muddy shores and flats near low-water mark.
^G. dibranchiata.^ Has a simple gill on both sides of the
parapodia; about eight inches long and one quarter of an inch wide
in the middle; proboscis one inch long and wider than the body on
the upper end. Abundant from New Jersey to Cape Cod.
ORDER =SEDENTARIA=
THE TUBICOLOUS WORMS
Many of this order construct tubes in which they live permanently.
Some species of both /Sedentaria/ and /Errantia/ have habits
pertaining to the other. These worms are without a protrusible
pharynx and without jaws. The body is usually divided into two or
three sections by segments and appendages of different forms. They
have hair-setæ on a limited number of segments only, varying with the
species; the remaining segments have /uncini/, or hooked comb-like
rows of setæ, which are very small, but often crowded in bunches.
Uncini exist also on segments having hair-setæ. Parapodia are often
lacking on the posterior parts and are usually without cirri. The
gills are usually confined to the anterior end and are sometimes
represented by tentacles around the head. The different species have
characteristic tubes, formed by mucus secreted by epidermal glands.
Sometimes the mucus hardens, making a parchment-like tube; again it
cements together grains of sand, or bits of shell, seaweeds, etc.
Some species secrete [pg181] calcareous tubes; these are often found
on rocks, in coral, and in the shells of mollusks. The anterior end
of the body is more highly developed than the posterior end.
FAMILY ~SPIONIDÆ~
GENUS ^Nerine^
^N. agilis.^ Two to three inches long; slender; somewhat flattened
at the anterior end; head conical and sharp; the two tentacles
about one half of an inch long; four eyes; color reddish-brown,
light green on the sides; gills red; tentacles greenish-white. It
burrows with extreme rapidity and lives on exposed beaches near
low-water mark.
^N. coniocephala.^ Two and a half inches long, one sixteenth of an
inch in diameter; head conical; body flattened on the dorsal side,
round on the ventral side; has two long tentacles turned backward
and a membrane on the gills of the anterior segments; gills red;
bristles long and numerous.
FAMILY ~CIRRATULIDÆ~
Worms of this family have a cylindrical body, more or less attenuated
at each end; segments similar throughout; many segments with long,
filamentous cirri which act as gills; and a conical head. They live
in burrows.
GENUS ^Cirratulus^
[Illustration: /Cirratulus grandis./]
^C. grandis.^ Four to six inches long; head acute; segments
numerous, short, and distinct; color dull yellow, or orange,
to brown, often iridescent beneath; ventral surface somewhat
flattened. Numerous long, filamentous, red to orange-colored cirri
extend nearly the whole length of the body and act as gills. It is
common in sand and gravel at low-water mark from Cape Cod to New
Jersey. [pg182]
FAMILY ~TEREBELLIDÆ~
The body is cylindrical and largest on the anterior end; there are
one to three pairs of more or less branched gills on the anterior
end, and the ventral surface of the anterior segments is thickened by
glands which secrete mucus for tube-building. These gland-spaces are
called /shields/.
GENUS ^Thelepsus^
^T. cincinnatus.^ Two to four inches long; pale red; marked like
lacework on the back; gills have numerous unbranched filaments
arising separately in two transverse rows; tubes thin, transparent,
flexible, and hung with foreign substances; attached along the
whole length.
GENUS ^Amphitrite^
[Illustration: /Amphitrite ornata./]
^A. ornata.^ Twelve to fifteen inches long; flesh-color, reddish,
or brown; three pairs of red plume-like gills and numerous
flesh-colored tentacles around the anterior end; tentacles
constantly in motion and sometimes extended eight or ten inches;
tubes a quarter of an inch or more in diameter, and firm, being
composed of sand and mud. It is found under stones in mud, gravel,
and sand at low-water mark from Cape Cod to New Jersey, often
associated with /Cirratulus grandis/.
GENERA ^Polycirrus^, ^Chætobranchus^
[Illustration: /Polycirrus eximius./]
^P. eximius^, ^C. sanguineus^. These are two species of bright-red,
fragile worms, found under stones, in mud. They do not form
tubes. The first is a small worm, the second twelve to fifteen
inches long. Both have long, crowded tentacles extending in
every direction and distended as the blood flows into them. /C.
sanguineus/ has [pg183] tentacles sixteen inches in extent, and
branched gills on short pedicels on the back. They are common in
mud at low-water mark from Cape Cod to New Jersey.
FAMILY ~AMPHICTENIDÆ~
GENUS ^Cistenides^
[Illustration: /Cistenides Gouldii./ ]
^C. Gouldii^ constructs conical free tubes of grains of sand in
a single layer; body short and a little curved; head obliquely
flattened; two broad groups of golden bristles turned upward on
each side of the anterior end; one to two inches long; color
light red or flesh-color, mottled with red or blue. This is a
common worm, and its horn-shaped tubes are so plentiful as to
attract attention on sandy shores. They will repay examination
with a glass, so beautifully are they built. The worm has
bunches of golden bristles arranged in two rows close to the
flattened anterior end, which make a kind of operculum to the
tube. This feature makes the species easy to identify. The worm
is transparent; the internal organs showing through give it the
various bright colors. It is found on sandy and muddy shores from
New Jersey northward.
FAMILY ~MALDANIDÆ~
The tubes of these animals are formed of sand, a short portion
projecting, and are very abundant in certain places. There is a horny
plate on the upper surface of the head, and the skin on the sides of
the head is raised in folds. There is a funnel-like process at the
posterior extremity; gills are lacking. Some of the segments in the
middle of the body are longer than the rest.
GENUS ^Clymenella^
[Illustration: /Clymenella torquata./ /a/, head and extended
proboscis, front view; /b/, posterior end; /c/, entire animal, side
view, natural size.]
^C. torquata.^ Body long, composed of twenty-two segments; the
fifth segment has a collar-like fold; the caudal extremity is
funnel-shaped and edged with papillæ; both [pg184] the first and
the last three segments are bare, the rest have short bristles
above and hooks below; head has a prominent convex plate with a
raised border; worm pale red, with bright-red bands around the
segments, sometimes brownish. It constructs nearly straight tubes
of pure sand close to low-water mark in sheltered coves, and ranges
from New Jersey northward.
GENUS ^Maldane^
^M. elongata.^ Six to eight inches long, one eighth to one quarter
of an inch in diameter; body cylindrical, cut obliquely at both
ends; head bordered by a slight fold; color brown, with red blood
showing through. Found in sandy mud at low-water mark, in firm,
deep tubes of fine mud, on the New England coast.
FAMILY ~ARENICOLIDÆ~
GENUS ^Arenicola^
^A. marina.^ Five to ten inches long; brownish-green; body
cylindrical, thickest on the anterior end; anterior and posterior
ends without chætæ; twelve to thirteen pairs of branched red gills
on the central segments. It makes burrows eighteen to twenty-four
inches deep on sandy southern shores, and can be traced by castings
at the mouth of the burrow. Commonly known as "lugworm," and used
by fishermen for bait.
FAMILY ~SABELLIDÆ~
In this family the gills arise from two semicircular bases forming
the crown; the second lobe of the anterior extremity is reversed like
a collar; the gill-filaments have secondary processes, and the tubes
are flexible, composed of cemented mud or sand. Found under stones,
the tube passing around the stone and opening upward.
GENUS ^Sabella^
^S. microphthalma.^ Length of tube one and a quarter inches,
diameter one eighth of an inch; body olive-green, specked with
white; wreath of tentacles half as long as the body; tentacles pale
yellowish or flesh-colored, with transverse lines of darker color.
It is found on the southern New England coast.
FAMILY ~SERPULIDÆ~
This family forms white calcareous tubes. One of the dorsal
gill-filaments is flattened, forming an operculum, or cover, with
[pg185] which the tube is closed when the worm has withdrawn itself
inside. The tubes are commonly found attached to shells and rocks,
usually solitary, but sometimes in clusters, crossing and recrossing
each other on the surface of the shell or rock. Plume-like gills
are attached to the anterior end of the body. The color differs
in different species. These worms may easily be mistaken for the
mollusks /Vermetus/, which live in similar tubes of larger size,
growing in masses.
GENUS ^Serpula^
^S. dianthus.^ Tubes often three inches long and one eighth of
an inch wide, the fixed end coiled and contorted, free end with
circular opening; tubes often show circular ridges, marking periods
of growth; operculum funnel-shaped, the exterior striated and the
edge bordered with short processes; wreath of gills nearly circular
and divided into two symmetrical parts; color variable. It is found
in tide-pools, also on the under side of rocks at low-water mark,
either solitary or congregated in masses, and ranges from Cape Cod
to New Jersey.
GENUS ^Spirorbis^
^S. borealis.^ A minute calcareous tube, in a close, flat coil
attached on one side; easily mistaken for a minute gasteropod
shell; worm has an operculum and wreath of gills. Found on the
fronds of seaweeds, on shells, etc.
CLASS =GEPHYREA=
This class of animals, once placed near the holothurians, belongs
with the annelid worms on account of their mode of development,
their structure being entirely dissimilar. They are without segments
and without parapodia. The body-cavity is filled with fluid and is
traversed by connective tissue and fine muscular fibers. They are
subcylindrical animals which can retract the anterior end of the
body. The mouth is surrounded by tentacles, or by tentacular folds,
and is at the base of the proboscis. They live in fissures of rocks,
in sand, mud, rock, or coral, and in deep gasteropod shells. Their
distribution is general.
ORDER =SIPUNCULOIDEA=
GENUS ^Sipunculus^
^S. nudus.^ The body is cylindrical, a foot or more in length
when extended. It is divided into two portions. The anterior end,
to the [pg186] extent of one sixth of the entire length of the
worm, is capable of being withdrawn into the remainder of the body.
This portion is called the /introvert/. The introvert is retracted
by means of special muscles forming a sheath around the gullet
and connected at the other end to the body-wall about half-way
down the body. It is narrower than the rest of the body and is
covered more or less closely with small horny papillæ which turn
backward and overlap like scales. The rest of the body is divided
into longitudinal furrows and circular markings, giving it the
appearance of being divided into squares. These markings correspond
to muscles which lie beneath. The introvert, when retracted, leaves
at the opening a lobed and plaited fold of the integument, giving
the appearance of tentacles. When the introvert is expanded there
is a fringe-like funnel around the mouth. The body is covered with
a horny cuticle and has an iridescent luster. The animal lives
buried in the sand and feeds upon sand, deriving its nourishment
from the organisms contained therein. The sipunculoids pass so much
sand and mud through their bodies that they are said to modify the
mineral substances on the bottom of the sea, as earthworms do the
soil of the land.
GENUS ^Phascolosoma^
^P. Gouldii.^ Body cylindrical, a foot or more in length, a
quarter or half of an inch in diameter when expanded; but the
body constantly changes in size and shape as it is contracted or
expanded; surface of body parchment-like in texture and marked off
in small squares; color dull white to light brown. It is found on
the New England coast in sand and gravel at low-water mark.
IV
MOLLUSCOIDA
TABLE SHOWING THE CLASSIFICATION OF THE MOLLUSCOIDA DESCRIBED IN THIS
CHAPTER
Class =POLYZOA=
Subclass =Ectoprocta= (/Excretory opening outside lophophore;
mouth in center of circle of tentacles; tentacles retractile/)
Order =GYMNOLÆMATA= (/Circular lophophore/)
Suborder ~CYCLOSTOMATA~ (/Tubular calcareous zoœcia,
with circular apertures devoid of closing apparatus/)
Set ARTICULATA (/Erect branches divided at intervals by
chitinous joints/)
Genera Species
^Crisia^ ^C. eburnea^
Set INARTICULATA (/Erect or adherent zoarium; unjointed/)
^Tubulipora^ ^T. flabellaris^
^Diastopora^ ^D. patina^
Suborder ~CHEILOSTOMATA~ (/Calcareous or chitinous
zoœcia, usually with opercula; avicularia, vibracula,
and ovicells often present/)
Set CELLULARINA (/Flexible erect forms/)
^Ætea^ ^Æ. anguinea^
^Eucratea^ ^E. chelata^
^Cellularia^ ^C. ternata^
^Caberea^ ^C. Ellisii^
^Bugula^ ^B. turrita^
^B. Murrayana^
^B. flabellata^
Set FLUSTRINA (/Cells quadrate; front wall of zoœcium
membranous or depressed, and has ridge-like margin/)
^Flustra^ ^F. membranacea^
^Membranipora^ ^M. pilosa^
^M. lineata^
^M. tenuis^
Set ESCHARINA (/Zoœcium wholly calcified/)
^Escharella^ ^E. variabilis^
^Mollia^ ^M. hyalina^
^Cellepora^ ^C. scabra^
^C. ramulosa^
^C. pumicosa^
Suborder ~CTENOSTOMATA~ (/Horny or gelatinous zoœcia,
having tooth-like processes which close the apertures when
the tentacles are retracted/)
^Alcyonidium^ ^A. ramosum^
^A. hirsutum^
^A. hispidum^
^A. parasiticum^
^Vesicularia^ ^V. dichotoma^
^V. custata^
Subclass =Entoprocta= (/Excretory opening within lophophore;
mouth near margin of area, which is surrounded by tentacles;
tentacles roll up instead of being retracted/)
^Pedicellina^ ^P. americana^
[pg190]
TERMS USED IN DESCRIBING POLYZOA
^Avicula´ria^: Specifically modified zoœcia, resembling a bird's
head, found only in the /Cheilostomata/.
^Brown bodies^: Brown pigment-masses contained in the zoœcia and
derived from the breaking down of the polypides.
^Lo´phophore^: The disk bearing the mouth and circlet of ciliated
tentacles.
^Orifice^: The open end of the zoœcium.
^Ovicell^: The receptacle in which the eggs develop.
^Pe´ristome^: The ridge around the orifice of cell.
^Po´lypide^: The parts of the animal within the zoœcium.
^Vibra´cula^: A lashing filament, or specifically modified zoœcia,
found only in the /Cheilostomata/.
^Zoa´rium^: The whole colony.
^Zoϫcium^: The body-wall of a single individual. [pg191]
POLYZOA
Among the numerous objects to be found on the beach at low tide
are the /Polyzoa/, of which there are said to be seventeen hundred
named species of the marine forms. These little animals, although
so plentiful, are inconspicuous, and it may be said that their very
existence is not known to those who are not professed naturalists;
yet they are easy to see, incrusting with a delicate calcareous
lacework the surface of stones and shells and seaweeds in the
tide-pools, and hanging from the rocks like branches of delicate
seaweeds. There is hardly a frond of even the fine red algæ on which
cannot be found the little tube holding shelly saucers, or the
creeping stems or branches of polyzoans. Any one of these little
masses, when examined with a pocket-glass, will surprise one with its
delicate and beautiful structure.
This class of animals is also called /Bryozoa/, and certain species
have the common names of sea-mats and corallines. They are broadly
divided into two groups, namely, the erect and the incrusting forms.
Those having tree- or plant-like shapes resemble seaweeds, while the
colonies which spread over stones, shells, and algæ resemble moss,
hence the name /Bryozoa/ (moss-animals). Both groups have the general
appearance of hydroids, because, like them, they are colonies having
plant forms and having their organisms inclosed in cup-like sheaths.
The resemblance, however, is but a superficial one, for the /Polyzoa/
have a much higher organization, each animal of the colony being a
separate and distinct individual. They can easily be distinguished by
the hair-like processes on the tentacles. The ciliated tentacles and
complete alimentary system are the conspicuous differences between
these colonies and those of the hydroids.
The /Polyzoa/ are very numerous and form a most attractive [pg192]
group. They are plentiful everywhere, occurring between tide-marks
and at great depths on the floor of the sea. Rocks protected from the
sun are often incrusted with the calcareous forms, while branching
species hang from the rocks and adorn rock pools. /Membranipora/,
in lace-like sheets, will be found on the larger seaweeds as well
as on various submerged objects. The beautiful little /Crisia/ may
be looked for on the fronds of red algæ, and /Alcyonidium/, in soft
moss-like patches, on /Fucus/. On some beaches are scattered the
sea-mats, /Flustra foliacea/, looking like bits of brown paper. A
pocket-lens will reveal the marvelous and orderly arrangement of the
two layers of cells, or zoœcia, placed back to back. There is not
a more surprising object in the animal kingdom than a living branch
of /Bugula/. The cells on its spiral, profusely branched clusters
have appendages resembling a bird's head, with its bill constantly
opening and shutting. Of the erect polyzoans some are entirely
calcareous and rigid; such species live in deep water, and their
colonies are called corallines, as are also the calcareous algæ. They
have existed in vast numbers since early geologic times, and are
plentiful in the Tertiary deposits, known as Coralline Crags. Other
erect forms have a calcareous framework, which is not continuous,
but has horny intervals, so that the colonies are flexible and can
be swayed by the tides in shallow water where they live. Others
have complete horny exoskeletons. The same differences occur in the
incrusting forms, those on the seaweeds being either flexible, so
that they bend with the plant, or if entirely calcareous are so small
that they do not break when the plant sways to and fro. Still others
are gelatinous and resemble bits of sponge. The calcareous forms are
usually ornamented with ridges which form beautiful patterns.
The individuals of the polyzoan colonies are small polyp-like
organisms which have a cup-like inclosure of horny or of calcareous
substance, or of the two combined, as mentioned above. This inclosing
sheath is the exterior or cuticle of the animal and is called the
/zoœcium/, the whole colony being called the /zoarium/. The animal
substance within the zoœcium is the /polypide/, and consists of
the mouth, tentacles, and alimentary system. A disk at the anterior
end of the body, bearing the circle of tentacles, is [pg193] the
/lophophore/; it is a contractile body, being, with the tentacles,
protruded from the zoœcium or drawn within it at will. In some
species the orifices of the zoœcia are surrounded with spines;
others have lids, called /opercula/, which shut down when the
polypides are retracted. A singular modification of the zoœcia is
seen in the genus /Bugula/, where peculiar shapes like birds' heads,
called /avicularia/, occur. In these singular appendages the upper
beak is hooked, while the lower one, or mandible, is the operculum of
the zoœcium. These constantly open and shut by means of muscles,
and although their function is not certainly known, it is thought
that they capture prey. Other modifications are whip-like processes,
or flagellate filaments, called /vibracula/, which constantly
beat the water. In many of the zoœcia of the colony there are
dark-colored masses, called /brown bodies/. These are formed by the
degeneration of the polypides, which at certain periods break down,
their tentacles and alimentary system ceasing to act and becoming
brown masses. The body-wall then puts out a bud internally and forms
a new polypide, which absorbs, or passes out, the brown body. The
term of life of a single polypide is not known, but in every colony
many such transformations are constantly taking place.
The colonies originally start from larvæ produced in the /ovicells/
of the zoaria. The ovicells are sometimes very large and pear-shaped,
occurring at intervals on the stems; or there may be one at the top
of each zoœcium. They look like pearls. A larva, when liberated,
swims about for a time, then attaches itself to a fixed object, and
increases, by budding, into some one of the various forms which the
colonies take.
SUBCLASS =ECTOPROCTA=
ORDER =GYMNOLÆMATA=
SUBORDER ~CYCLOSTOMATA~
ERECT OR CREEPING POLYZOA
The zoœcia are more or less cylindrical; the upper ends are
sometimes completely free and sometimes closely adherent. The
[pg194] opening of the cell has no operculum. Ovicells, containing
the embryos, appear like pear-shaped swellings.
GENUS ^Crisia^
[Illustration: /Crisia eburnea/; a branch bearing ovicells, highly
magnified.]
^C. eburnea.^ This species is found in tide-pools on algæ,
especially on the red seaweeds, growing in bushy tufts from one
half of an inch to an inch high. Calcareous, with horny joints;
cells in two rows, semi-alternate, cylindrical, free at one end,
bent; no operculum; ivory-white; ovicells large and pear-shaped.
Common from Long Island Sound northward and on the Pacific coast.
GENUS ^Tubulipora^
^T. flabellaris.^ This species is found attached to slender
branched algæ, in coral-like masses of long, crooked, tubular
cells united at the base and spreading into fan-shapes placed flat
against the fronds. It is sometimes one quarter of an inch in
diameter. On the same alga may often be found /Crisia/, /Mollia/,
and /Cellepora/. (Plate XLIX.)
GENUS ^Diastopora^
^D. patina.^ Tubular cells rise from a saucer-shaped disk about a
quarter of an inch in diameter; cells lie obliquely or stand erect,
and are crowded toward the center; margin of disk without cells;
colony white and calcareous. Found on algæ and eel-grass from Long
Island Sound northward.
SUBORDER ~CHEILOSTOMATA~
In this suborder the zoœcia are either horny or calcareous, and
the orifices are usually surrounded with spines and have opercula.
The orifices generally have raised margins, or peristomes. Ovicells
form helmet-like coverings overhanging the orifices.
GENUS ^Ætea^
^Æ. anguinea.^ Delicate, white, creeping, calcareous stems, from
which rise numerous club-shaped cells, about one eighth of an inch
high, each one with an aperture in the end. This species creeps in
wavy lines along the fronds of algæ, and is frequently found on
/Dasya/, /Griffithsia/, /Plocamium/, and eel-grass.
[Illustration: PLATE XLIX. Tubulipora flabellaris. 1, Tubulipora
flabellaris, natural size. Eucratea chelata. Cellularia ternata. 1,
Cellularia ternata, natural size.]
[Illustration: PLATE L. Caberea Ellisii. Bugula turrita. 1, Bugula
Murrayana; 2, B. Murrayana, magnified; 3, B. Murrayana, a few cells,
more highly magnified; 4, B. flabellata; 5, B. flabellata, magnified.]
GENUS ^Eucratea^
^E. chelata.^ A small, delicate species rising from a creeping
stem. It has branches composed of single rows of horn-shaped cells
having an oblique aperture on the side. Found at extreme low-water
mark on hydroids, shells, stones, and /Fucus/. (Plate XLIX.)
GENUS ^Cellularia^
^C. ternata.^ Zoarium filamentous, spreading, about one inch high,
white, calcareous, branched in a forking manner; cells long,
narrowest at base, arranged in series of three and on the same
plane, apertures oblique and facing one way; horny joint between
each cluster of cells. This species grows in deep water from Cape
Cod northward, and is found on objects washed upon the beach.
(Plate XLIX.)
GENUS ^Caberea^
^C. Ellisii.^ Zoarium erect, with fibrous base, leaf-like, branches
in a forking manner; branches straight, stiff, narrow, spreading;
cells arranged in rows of three, adherent throughout; long bristles
emanate from near base of many cells; egg-capsules globular,
smooth, pearly. Common from Cape Cod northward in deep water.
(Plate L.)
GENUS ^Bugula^
[Illustration: 1, /Bugula turrita/, enlarged; 2, the same, a
branchlet, highly magnified; 3, the same, a branchlet, bearing
ovicells.]
^B. turrita.^ This is a very abundant species, found everywhere
along the coast from Maine to North Carolina. Large quantities of
it are [pg196] sometimes thrown upon the beach by storms. It
grows in erect tufts, sometimes a foot long, and is much branched;
the branches grow around the stem in a spiral manner, forming
dense clusters. The lower part of the stem is often naked (having
lost the branches) and bright orange in color, while the tufts of
branches at the top are pearly-white or yellowish. The cells are
long, with a long, pointed spine on the upper outer angle. Like all
species of /Bugula/, it has bird-head appendages, which can be seen
under a powerful glass. (Plate L.)
^B. Murrayana.^ Clusters of broad, thin, flexible fronds, one
to two inches high, attached by a slender base and spreading in
entangled masses; fronds wedge-shaped, flat, dividing in a forking
manner; outer cells have bristle-like filaments, which constantly
beat the water; all cells have avicularia, or bird-head appendages.
(Plate L.)
^B. flabellata.^ Fan-shaped fronds of flat branches, divided in a
forking manner; the cells are arranged in four or five longitudinal
rows, are oblong, with a spine at each side of the circular
aperture, and are capped with pearl-like ovicells. This species,
like others of the genus, bears the very singular structures known
as avicularia, or bird-head appendages. They show, under a strong
glass, a hooked beak, like that of the hawk or parrot. These beaks
are attached by flexible stems and are provided internally with
powerful muscles by which they are constantly opened and closed;
the beak can bite with considerable force. In this species they are
attached to the sides of the cells. (Plate L.)
GENUS ^Flustra^
^F. membranacea.^ This species forms gauze-like incrustations on
the fronds of seaweeds, and is common on /Fucus/ and /Laminaria/,
spreading irregularly over several inches of space. The cells are
oblong, quadrangular, with a blunt, hollow spine at each angle.
Many specimens have simple horny tubes, closed on top, rising from
some of the cells to the height of half an inch. (Plate LI.)
[Illustration: PLATE LI. Flustra foliacea. 1, 2, Cellepora pumicosa,
natural size; 3, C. pumicosa, magnified; 4, C. ramulosa. 1, Flustra
membranacea; 2, 3, F. membranacea, magnified. Vesicularia dichotoma.]
GENUS ^Membranipora^
^M. pilosa.^ An incrusting variety, composed of a single layer of
cells spreading irregularly over the surfaces of stones, shells,
and seaweeds, sometimes completely covering the fronds of /Chondrus
crispus/, /Phyllophora/, /Rhodymenia/, and other algæ. The cells
are membranaceous, with a calcareous rim, and have one long hair
and several small ones surrounding the large roundish apertures. It
is found in abundance on the shores from Long Island Sound to the
Arctic Ocean.
[Illustration: 1, /Membranipora pilosa/; a few of the cells seen
from above, magnified. 2, /Membranipora pilosa/; a single cell,
seen in profile.]
^M. lineata.^ Cells oblong, crowded, closely adherent; slender
spines on edge of aperture, which bend over and meet across it;
incrusts rocks and shells in broad, thin, radiating patches; cells
[pg197] much smaller and narrower than those of /M. pilosa/;
easily distinguished from that species by its manner of spreading
and the absence of the one long hair. Common from New Jersey
northward.
^M. tenuis.^ Common on pebbles, often covering their whole surface
with a lace-like incrustation of very small oblong cells having a
three-lobed aperture. Found in Long Island Sound and north to Cape
Cod.
GENUS ^Escharella^
^E. variabilis.^ This species forms calcareous incrustations on
shells or pebbles. The layers are thin, but eventually overlap one
another, and the incrustation sometimes becomes an inch thick and
resembles coral. The color of the living animal is dull red. The
species ranges from Cape Cod to South Carolina, and is abundant in
Long Island Sound.
GENUS ^Mollia^
^M. hyalina.^ Cells subcylindrical, irregular, transparent, smooth,
and more or less oblique. The species forms small circular disks on
algæ in tide-pools.
GENUS ^Cellepora^
^C. scabra.^ It forms branching, coral-like masses on slender red
algæ.
^C. ramulosa.^ Branches cylindrical, rough, dividing in a forking
manner, spreading, two to three inches high, calcareous; cells
urn-shaped, irregularly arranged, apertures contracted, long spine
on the outer edge. It is found in deep water attached to shells,
and in tide-pools, where it grows chiefly on /Sertularia/ and other
hydroids and on slender red algæ. It ranges from Long Island Sound
to Greenland. (Plate LI.)
^C. pumicosa.^ Cells urn-shaped, irregularly crowded together,
forming a conglomeration of porous, brittle masses, not exceeding
an inch in breadth, usually round when small, oblong and knobbed
when large; spine on outer margin of aperture. It incrusts stones
and the stems of /Fucus/. (Plate LI.)
SUBORDER ~CTENOSTOMATA~
GENUS ^Alcyonidium^
^A. ramosum.^ Twelve to fifteen inches high; much branched;
branches smooth, cylindrical, one third of an inch in diameter,
usually crooked; branches in a forking manner; color rusty-brown.
Abundant in shallow water, attached to rocks, from New Jersey to
Cape Cod.
^A. hirsutum.^ A species common on seaweeds, sometimes completely
covering them, forming dirty, straw-colored, thick, cartilaginous
crusts covered with numerous conical papillæ. These are the
cells, or zoœcia; they are surrounded with spines. Circular
yellow spots occur over the surface, which are clusters of eggs.
A good pocket-lens will show the cells, laid in beautiful order,
and perhaps the extended tentacles. Found from Long Island Sound
northward. [pg198]
^A. hispidum.^ One of the most common species found incrusting
the fronds of /Ascophyllum/ at low-water mark. It forms fleshy,
brown, soft crusts of moderate thickness, and has spines scattered
over the otherwise smooth and glistening surface. The cells are
inconspicuous, and each one has five long rigid bristles. Habitat,
Long Island Sound to Greenland.
^A. parasiticum.^ It forms thin, earthy crusts on algæ and
hydroids. The surface is porous; the cells are distant and arranged
irregularly, and seem as if composed of sand cemented with mud.
GENUS ^Vesicularia^
^V. dichotoma^ (^Valkeria pustulosa^). This species grows in
clusters of crowded slender stems, which branch in a forking
manner, the branches dividing in different planes, making a
tree-like form one to three inches high. At the points where the
branches divide is a dark, opaque substance, and at these points
also the cells are crowded in clusters of spiral rows and are
greenish-brown in color. The dark spots are in marked contrast to
the white translucent substance of the rest of the stem, giving a
spotted aspect to the whole. (Plate LI.)
^V. custata.^ Delicate, thread-like, jointed stems, with slender
opposite branches; cells small and elliptical, arranged mostly
in clusters. Found creeping like a small dodder-plant over other
polyzoans, hydroids, and seaweeds.
SUBCLASS =ENTOPROCTA=
GENUS ^Pedicellina^
^P. americana.^ A very small species. Club-like zoœcia rise
from slender, white, creeping stems; tentacles roll up instead of
retracting into the cups. Found on hydroids, other polyzoans, and
algæ.
V
ECHINODERMATA
Phylum
=ECHINODERMATA=
Classes
=ASTEROIDEA=
(/Starfishes/)
=OPHIUROIDEA=
(/Brittle-stars/)
=ECHINOIDEA=
(/Sea-urchins/)
=HOLOTHUROIDEA=
(/Sea-cucumbers/)
=CRINOIDEA=
(/Feather-stars and Sea-lilies/)
[pg201]
TERMS USED IN DESCRIBING THE STRUCTURE OF ECHINODERMS
^Abo´ral surface^: The side opposite the mouth.
^Ambula´cra^: Tubular feet used in moving.
^Ambulacral zones^: The five areas containing the rows of tube-feet.
^Ampul´læ^: Reservoirs or vesicles at the base of the tube-feet.
^Auricula´ta^: The larval stage of holothurians.
^Bipinna´ria^ or ^Branchiolaria^: The larval stage of starfishes.
^Dorsal surface^: The back of the animal, generally, but not
necessarily, the upper side.
^Exoskeleton^: Outside framework or support, differing from a true
skeleton which lies inside the body.
^Interambulacral areas^: The five areas between the ambulacral
zones.
^Larva^: The animal in a stage of development from the time it
leaves the egg until it reaches the complete form of the species.
^Madreporic plate^: A sieve-like plate of carbonate of lime.
^Oral surface^: The side on which the mouth is placed.
^Ossicles^: Calcareous plates which cover the body and form the
exoskeleton.
^Pedicella´riæ^: Small spines which have divided ends, like
scissors or forceps.
^Plu´teus^: The larval stage of sea-urchins.
^Po´lian vessels^: One to ten sacs arising from the ring-canal.
^Ring-canal^: The canal around the mouth.
^Spines^: Processes which rise from the surface of the animal.
^Stone-canal^: A calcareous tube leading from the madreporic plate
to the ring-canal.
^Suckers^: Sucking-disks on the ends of the tube-feet.
^Ventral surface^: The side opposite the dorsal surface.
^Water-vascular system^: A series of canals which conduct water
through the animal. [pg202]
ECHINODERMATA
The echinoderms, although their shapes are very unlike in the
different classes, have the same general internal structure, and
also other features which place them together in one group. They are
radiates (page 113) of the highest type; they have an exoskeleton;
and many of them are beset with spines, from which the name is given.
They have locomotor organs, the /ambulacra/, and a /water-vascular
system/ peculiar to themselves. Some have the very strange power of
casting off, and developing again, parts of the body.
The development from the egg to the adult is remarkable, and of
unusual interest to naturalists. The larval stage of echinoderms
is so unlike the mature animal that for a long time the larvæ were
thought to be another class of animals, and therefore were given the
names which they still retain.
In observing echinoderms it will be seen that the dorsal part is
carried uppermost by some, such as the starfishes and sea-urchins.
In the former the back is broad and extended; in the latter it is
curved and contracted. But in crinoids the back is carried downward
and is extended like a stalk; in the sea-cucumbers (holothurians)
the dorsal and ventral surfaces are parallel with the long axis of
the cylindrical body, instead of being on a plane with the mouth and
excretory opening. Owing to the unusual positions of the dorsal and
ventral surfaces, the terms /oral/ (mouth side) and /aboral/ (side
opposite the mouth) are generally used in describing these species.
The surface of the body is divided definitely by the ambulacra, the
/ambulacral zones/, and the /interambulacral spaces/, but differently
in the different classes. The movement of the animals is [pg203]
effected by means of the tube-feet, or ambulacra. These have suckers,
which are attached or released by the power of the water-vascular
system. The /madreporic plate/, which can be distinctly seen in
starfishes at the angle of two of the arms, is a calcareous porous
plate which opens into the /stone-canal/. This canal passes through
the body and opens into a circular tube which runs around the
mouth. A system of canals extends from this circumoral tube, or
/ring-canal/, and eventually one canal opens into each tube-foot.
Water, entering by the madreporic plate, passes through the various
canals and into the tube-feet, which it distends. When the feet are
pressed against a substance and the water is withdrawn, a vacuum is
formed, which causes the disk-ends of the feet to act like suckers.
When the feet are again flooded the hold is relaxed. Thus the animal
drags its body along with a slow, gliding motion. The madreporic
plate, being calcareous, is said to act as a filter, purifying the
water as it passes into the body, which it furnishes with oxygen as
well as with locomotive power.
[Illustration: Aristotle's lantern.]
A curious organ found in the /Echinoidea/ (sea-urchins) is called
/Aristotle's lantern/. It is a complicated arrangement, not fully
understood, having forty parts, and is connected with the alimentary
system. One of the parts is the mouth, over which five teeth project.
These teeth grasp and grind the food. The exoskeleton is composed
of plates of carbonate of lime, called /ossicles/, which cover the
surface of the body. The ossicles are of various sizes and shapes,
and are one of the determining features in classification. They may
be scattered spicules of lime, separated plates joined by connecting
rods, or overlapping plates; or they may be fitted together so as to
form a continuous shell. The starfishes are usually carnivorous, the
sea-urchins usually vegetarian, while the holothurians, after the
manner of worms, take in sand and mud, deriving their nourishment
from the organic particles contained in them. All echinoderms live in
the sea. [pg204]
TABLE SHOWING THE CLASSIFICATION OF THE STARFISHES DESCRIBED IN THIS
CHAPTER.
Class =ASTEROIDEA= (/Starfishes/)
Order =PHANEROZONIA= (/Ossicles not crowded; large marginal
ossicles; spines only on dorsal surface; pedicellariæ sessile/)
Families Genera Species
~PORCELLANASTERIDÆ~ ^Ctenodiscus^ ^C. corniculatus^
~ASTROPECTINIDÆ~ ^Astropecten^ ^A. articularis^
^Psilaster^ ^P. floræ^
^Luidia^ ^L. senegalensis^
^L. clathrata^
^L. alternata^
~PENTAGONASTERIDÆ~ ^Mediaster^ ^M. æqualis^
~ANTHENEIDÆ~ ^Hippasteria^ ^H. phrygiana^
~PENTACEROTIDÆ~ ^Pentaceros^ ^P. occidentalis^
^P. reticularis^
^Nidorella^ ^N. armata^
~ASTERINIDÆ~ ^Asterina^ ^A. folium^
^A. miniata^
Order =CRYPTOZONIA= (/Ossicles crowded; pedicellariæ stalked/)
~SOLASTERIDÆ~ ^Solaster^ ^S. endeca^
^S. decemradiata^
^Crossaster^ ^C. papposus^
~ECHINASTERIDÆ~ ^Cribrella^ ^C. sanguinolenta^
^Echinaster^ ^E. sentus^
~HELIASTERIDÆ~ ^Heliaster^ ^H. multiradiata^
~ASTERIIDÆ~ ^Asterias^ ^A. vulgaris^
^A. Forbesii^
^A. ochracea^
^A. gigantea^
[pg205]
CLASS =ASTEROIDEA=
THE STARFISHES
These animals are named from their star-shaped outline. Some have
five long, spreading arms diverging from a small disk, which is
hardly more than their point of union; others have a large body with
short arms, which are like angular projections of the body, giving
a pentagonal shape. Some genera have a greater number of arms than
others; /Solaster/ has eleven to thirteen, and /Heliaster/ (the
sun-stars, found on the west tropical coast) has thirty to forty.
[Illustration: Diagram of water-vascular system of a starfish: /a/,
madreporite; /b/, stone-canal; /c/, ring-canal; /d/, radial canals;
/e/, ampullæ; /f/, ambulacra.]
The mouth of the starfish is in the center of the ventral side. A
ventral or /ambulacral groove/ extends through each arm. In these
grooves the ambulacra, or tube-feet, are arranged in rows. The
/ambulacra/ are hollow, cylindrical bodies, each of which has a
sucker at one end, and is connected at the other end with a little
globular body, the /ampulla/. The ventral groove forms a ridge in the
body-cavity. It is called the /ambulacral zone/, and is formed by a
double row of elongated plates, which meet and form a raised line
along the middle of the inside of the arms, and appear like ribs;
between them lie the ampullæ. These plates are called the /ambulacral
ossicles/. Numerous other ossicles extend over the surface, buried
in the integument of the body, making a calcareous network, or
/exoskeleton/. The ossicles are connected by muscles so that the
animal is not rigid, but is able to bend the body and even creep
through comparatively small places. The ossicles are covered with
/spines/ of two kinds. The very minute ones are the /pedicellariæ/,
and have a jointed end which opens and shuts like a pincers. Their
principal use seems to be to remove waste matter or other substances
from the body, keeping it free and clean. The pedicellariæ are
arranged, in some species, in circles around the [pg206] bases
of the spines, and form groups over the dorsal surface. Examining
the backs of different starfishes with a strong magnifying-glass,
one will be surprised to see the varied grouping of the spines and
pedicellariæ. At the extremity of each arm is a red eye-spot, which
is sensitive to light, and a tube-foot, which has no sucker and which
is believed to act both as an olfactory and as a feeling organ. The
madreporic plate lies at the angle of two of the arms or rays. Water
filters through the madreporic plate and passes by the stone-canal to
the ring-canal around the mouth, and thence to the radial tubes, one
of which extends through each arm and is connected by a branch with
each tube-foot. At the base of each tube-foot there is a globular
reservoir, or ampulla. A valve connects the tube-foot and ampulla.
When the ampulla is contracted, water is forced into and distends
the tube-foot; when the ampulla is distended, it withdraws the water
from the tube-foot, thus acting like a suction-bulb. When water
is sent into the tube-feet they are greatly extended and are then
placed against an object. The water being then withdrawn through the
ampullæ, a vacuum is formed, and the suckers are tightly attached.
By the alternating movements of the ambulacra the animal is dragged
slowly along and moves with a gliding motion. It does not deviate
from a straight path, going over elevations or through depressions
without turning aside; its body conforms to the irregularities of
the road and never bridges over spaces. The stomach extends a little
way into the arms, and a short intestine leads to the excretory
opening in the center of the back. Starfishes are carnivorous and
voracious, and are particularly [pg207] destructive to oyster-beds.
The animal fastens itself to a bivalve, and protrudes a part of its
stomach, with which it envelops its prey and slowly sucks it out of
its shell. When feeding on small mollusks they take them into the
stomach directly. Starfishes regain by natural growth parts of the
body which may be lost. Sometimes the animal throws off an arm to
escape capture, and self-mutilation also occurs where unfavorable
conditions exist. Oystermen formerly were ignorant of the starfish's
wonderful powers of regeneration, and were in the habit of cutting
up those captured in their forks and throwing them overboard, thus
increasing the number instead of destroying their enemies, as each
arm with a piece of the body attached to it will, it is said, become
a new individual. This tenacity of life makes starfishes difficult
to destroy, and they are exceedingly plentiful in all seas. One
naturalist speaks of seeing on the coast of Maine a bed of starfishes
which extended several miles and covered the bottom so closely that
he picked sixty individuals off a small stone. On the northern
shores of the Pacific coast they abound in great variety, and some
are of unusual size. /Asterias gigantea/ of this region measures
two feet across. Another species, /Phyncopodia helianthoides/,
measures a yard in diameter, and has twenty or more arms. The most
common species of the Atlantic coast are /Asterias vulgaris/ and /A.
Forbesii/; the former ranges from Long Island northward, the latter
from Massachusetts to Florida. These are the species particularly
destructive to oyster-beds. /Asterias vulgaris/ sometimes grows to be
fifteen inches in diameter; from this, which is perhaps the largest,
are found starfishes of all sizes down to the very small /Cribrella/.
They inhabit all varieties of bottoms, from low-water mark to deep
water. They are not always abundant in the same place, but seem to
move about.
Some oystermen believe that the starfishes get into masses like a
ball and are rolled along by the tide. This idea comes from the fact
that an oyster-bed may be free from them one day and the next be
covered by these pests. To get rid of them the beds are swept over
with a tangle, which is an iron bar holding swabs of raveled rope.
The spines of the starfish are caught in the [pg208] tangle, and
often hundreds are brought up in one haul and are then killed by
steaming.
The anatomical system of the starfish is easily traced by cutting
off, with scissors, the skin from the dorsal surface of the disk, and
also cutting a slit down one of the arms. In the center of the body
will be seen the upper part of the stomach, a small star-like spot,
from which radiate five branches, which divide and lead into the
much-ramified, plume-like organs which extend through the arms. These
are the pyloric cæca, whose function is to secrete the digestive
fluids. The much-folded stomach occupies the greater part of the
central space, its large convolutions showing on top. The mouth
connects with the stomach on the ventral side. By turning back the
skin from the arm, small filiform processes can in some large species
be seen; these are the dermal branchiæ, or breathing-organs, which
may either project through pores in the skin between the ossicles or
be entirely retracted. If the pyloric cæca be laid back, one can see
the rib-like arrangement of the ambulacral ossicles, and also the
ampullæ, which lie between the ossicles on each side of the ridge. If
an ampulla be inflated and then pressed, the corresponding tube-foot
will be seen to extend. To follow successfully the water-vascular
system, beginning in the madreporic plate and extending through the
stone-canal to the ring-canal around the mouth and thence through the
arms, requires a strong glass and more skilful manipulation.
ORDER =PHANEROZONIA=
FAMILY ~PORCELLANASTERIDÆ~
GENUS ^Ctenodiscus^ (Plate LII.)
^C. corniculatus.^ Pentagonal; about two and a half inches in
diameter; the body flat, with wide marginal plates, giving a
flat edge to the rather long, pointed arms; madreporic plate
large; color greenish; ambulacra without suckers, seeming to be
adapted to pushing through soft mud rather than dragging over hard
surfaces. It lives in deep water on muddy bottoms and ranges from
Massachusetts to Greenland. When dredged the animal is usually
found to be filled with soft mud.
FAMILY ~ASTROPECTINIDÆ~
In this family there are only two rows of tube-feet; the rays end in
sharp points and have large ossicles on the margins. [pg209]
GENUS ^Astropecten^
^A. articularis.^ The body is flat and smooth; the rays sharply
pointed and conspicuously bordered with marginal ossicles and
fringed with short spines; two rows of ambulacral feet; color rich
purple. Found in shallow waters of South Atlantic coast on sandy
bottoms. (Plate LII.)
GENUS ^Psilaster^
^P. floræ.^ Diameter four to five inches; arms sharply pointed
and conspicuously bordered with large ossicles; body flat, with
smooth surface, the ossicles seeming like mosaic; bright pinkish
flesh-color. It occurs in deep water off the eastern coast as far
south as New Jersey.
GENUS ^Luidia^
This genus of starfishes is celebrated for its peculiar habit of
breaking in pieces when taken from the water, and therefore good
specimens are almost impossible to obtain.
^L. senegalensis.^ Twelve to fourteen inches across; arms long and
narrow, tapering to a point and fringed on the edges with spines;
surface rather smooth, showing the separation of the ossicles;
color almost white, with dark line running through the center of
each arm; usually nine arms. Found in shallow water on the coasts
of Florida and the Gulf of Mexico.
^L. clathrata.^ Four to five inches across; light-colored; with
a fringe of spines on the margins of the arms, which taper to
a point; two rows of ambulacra. It is found from New Jersey
southward, and is one of the most common starfishes on the sandy
beaches of North and South Carolina. (Plate LII.)
^L. alternata.^ Upper surface purplish, with irregular yellowish
bands on the arms; under surface yellow. Found in shallow water on
the Florida coast.
FAMILY ~PENTAGONASTERIDÆ~
GENUS ^Mediaster^
^M. æqualis.^ Body flat; the five rays equal or exceed in length
the diameter of the disk; margins have double row of large plates;
surface covered with granules, which are easily rubbed off; bright
red above, pale orange below; diameter four inches. Common on the
coasts of Oregon and California.
FAMILY ~ANTHENEIDÆ~
GENUS ^Hippasteria^
^H. phrygiana.^ This beautiful starfish lives in deep water, but
is sometimes thrown up on the beach, and ranges from Cape Cod
northward. [pg210] It has a large, pentagonal, bright-scarlet
disk, five to six inches in diameter, with arms rather long and
pointed. The upper side is raised and cushion-like, and is covered
with blunt spines; the margins have larger spines of the same
shape. The pedicellariæ are sessile and so long and large as to be
easily seen with the naked eye. (Plate LII.)
FAMILY ~PENTACEROTIDÆ~
GENUS ^Pentaceros^
^P. occidentalis.^ Pentagonal; eight to twelve inches in diameter;
ossicles a network of rod-like plates, with prominent spines at
the points of union; body inflated in the center and running in
wedge-like form to the ends of the rather long and narrow arms; the
upper lines of the ridges have spines more prominent than those
on the rest of the body; the spines of the larger specimens are
more like large warts or small hemispheres. Found on the Lower
California coast.
^P. reticularis.^ This starfish is the largest species on our
coasts. It is common in southern Florida close to the shore. The
body is three to four inches thick, flat on the oral surface, but
raised on the upper side, and tapers down in wedge-like form to the
points of the short arms. The prominent blunt spines which cover
its surface are arranged in a somewhat regular net-like order, and
the sharp-edged margins have an even row of larger spines of the
same form. The madreporic plate is nearly in the center of the
disk, and is quite conspicuous, being bordered with a circle of
small spines. Its color is dull yellow, and its size often a foot
or more in diameter. It is the large starfish so often seen in
curiosity-shops. (Plate LII.)
GENUS ^Nidorella^
^N. armata.^ This very curious pentagonal species, found on the
California coast, is five to six inches in diameter and red in
color. The upper surface is raised and covered with thick, pointed
spines one half of an inch to one inch long, arranged in lines, but
not crowded. The ossicles on the margins are large; some of them
are hemispherical and bear large spines. Smaller spines border the
under edge of the margins. (Plate LIII.)
FAMILY ~ASTERINIDÆ~
The starfishes of this family are pentagonal, with a large body and
short arms. The disk is more or less elevated in the center, and the
edges are sharp. There are two rows of ambulacra. The ossicles are
notched and overlapping. The family is confined to temperate and
tropical waters.
GENUS ^Asterina^
^A. folium.^ Small, pentagonal, swollen (gibbous). Found on the
Florida coast.
[Illustration: PLATE LII. Ctenodiscus crispatus. Astropecten
articularis. Luidia clathrata. Hippasteria phrygiana. Pentaceros
reticularis.]
[Illustration: PLATE LIII. Nidorella armata. Asterina miniata.
Solaster decemradiata. Crossaster papposus.]
^A. miniata.^ Pentagonal; somewhat raised in center; about one and
a half inches across; edges sharp. Found on the California coast
close to shore. (Plate LIII.)
ORDER =CRYPTOZONIA=
FAMILY ~SOLASTERIDÆ~
GENUS ^Solaster^
^S. endeca.^ Dark red in color; nine to eleven arms, which are
shorter than the breadth of the disk; diameter of disk about five
inches; two rows of ambulacra; surface rather smooth. Common on
the coast of Maine, and found from Cape Cod to Newfoundland below
low-water mark.
^S. decemradiata.^ This species is common on the North Pacific
coast. It has ten arms, which are about twice the length of the
diameter of the body, the whole body being about a foot across.
(Plate LIII.)
GENUS ^Crossaster^
^C. papposus.^ Twelve to fifteen arms, half as long as the breadth
of the body; upper surface an open network of calcareous rods,
or ossicles; at their points of union are club-shaped tubercles
bearing tufts of smaller spines; concentric lines and spots of red
and purple over the spiny upper surface; color light underneath.
Common on the New England coast. (Plate LIII.)
FAMILY ~ECHINASTERIDÆ~
GENUS ^Cribrella^
^C. sanguinolenta.^ This species is abundant north of Cape Cod and
is found of all sizes from half an inch to two inches in diameter
and of various colors—purple, orange, red, yellow, flesh-color,
etc. It has five round arms, generally about four times as long as
the breadth of the disk. The ends are often turned upward. It is
covered with crowded short spines, like little warts, which give
it a nearly smooth surface. It has two rows of ambulacra. It moves
with two of its arms turned forward, as if they were dragging the
other three behind them. Unlike most species, the young are not
free-swimming, but the eggs are carried around the mouth of the
mother, and the young are retained there until they are capable of
taking care or themselves. (Plate LIV.)
GENUS ^Echinaster^
^E. sentus.^ This species occurs close to shore in the waters of
Florida and is perhaps the most commonly observed species on the
beach. It extends as far north as New Jersey. It is purplish in
color, and about four and a half inches in diameter, with two rows
of ambulacra, five arms, and a surface rough with spines. [pg212]
FAMILY ~HELIASTERIDÆ~
GENUS ^Heliaster^
^H. multiradiata.^ Spines on the upper surface of rays in five
rows, but close to the disk proper become reduced to one row. Found
on the coasts of Lower California and Mexico. (Plate LIV.)
FAMILY ~ASTERIIDÆ~
The /Asteriidæ/ have the following characteristics: four rows
of tube-feet; ossicles small and unequal; spines isolated or
grouped; pedicellariæ of two forms, forceps-like and scissors-like
respectively. They include the very common forms found on all beaches.
GENUS ^Asterias^
^A. vulgaris.^ The common starfish of the Atlantic coast, from
Long Island Sound to Labrador. It occurs at low-water mark and
extends into deep water. It has five arms, which taper to a point.
Large specimens measure fifteen inches across. The upper surface
is rough, being covered with short spines, which are largest and
thickest at the edges of the rays, and surrounding them are the
pedicellariæ. The color varies from pink, yellow, and brown to
purple.
^A. Forbesii.^ The common starfish of the Atlantic coast, from
Massachusetts Bay to the Gulf of Mexico. This species resembles
very closely /A. vulgaris/, but can be distinguished from it by
the madreporic plate, which is bright orange, while in the former
it has the same color as the animal; also the arms are a little
swollen at the base and terminate more bluntly. These two species
are very destructive to oyster-beds, especially where their ranges
overlap. It is computed that they destroy annually two hundred
thousand dollars' worth of oysters. Vast numbers congregate where
the feeding-ground is good, and move in long lines from place
to place. The oystermen dredge over the beds and bring them up
in thousands, then steam them or throw them on the shore above
high-water mark. (Plate LIV.)
^A. ochracea.^ The common starfish of the Pacific coast, from
Sitka to San Diego. Five rays, each hardly twice as long as the
diameter of the body; spines running irregularly over the surface,
but forming a pentagon at the middle of the disk and inclosing the
madreporic plate; diameter eight inches. It is very common near San
Francisco on rocks at low-water mark. (Plate LIV.)
^A. gigantea.^ Body very large and swollen; six rays, somewhat
less in length than twice the diameter of the disk; aboral surface
covered with numerous short, blunt, equidistant spines of uniform
size and regularly distributed; spines contracted at the base and
striated; diameter two feet. Found on the California coast.
[Illustration: PLATE LIV. Cribrella sanguinolenta. Heliaster
multiradiata. Asterias Forbesii. Asterias ochracea.]
TABLE SHOWING THE CLASSIFICATION OF THE BRITTLE-STARS DESCRIBED IN
THIS CHAPTER.
Class =OPHIUROIDEA= (/Brittle-stars/)
Order =EURYALIDA= (/Skin without plates; arms simple or branched,
and capable of being rolled up/)
Genera Species
^Astrophyton^ ^A. Agassizii^
Order =OPHIURIDA= (/Skin with plates/)
^Ophiopholis^ ^O. aculeata^
^Amphiura^ ^A. squamata^
^Ophiocoma^ ^O. riisei^
^O. æthiops^
^O. Alexandri^
^Ophiothrix^ ^O. angulata^
[pg214]
CLASS =OPHIUROIDEA=
BRITTLE-STARS
The ophiurans, or brittle-stars, differ from the starfishes in having
the arms quite distinct from the body. In starfishes the arms are
extensions of the body, and the viscera extend partway into them,
while in ophiurans the body is a central disk, with the five narrow
arms attached to its margin. In form they suggest a spider, and
sometimes are called sea-spiders. The name brittle-star is also
descriptive, since they break off their limbs readily. The arms are
narrow, taper to a point, usually curl at the ends, and have no
ambulacral grooves, but are completely covered with bare calcareous
plates (except in the first order, where they have a skin and no
plates). The ambulacra are small spines without suckers, which
emanate from the sides or margins of the arms and do not serve for
walking. The madreporic plate is on the ventral surface, in one of
the circular shields which surround the mouth. The alimentary canal
ends blindly. The egg-sacs lie between the arms and open by slits on
the under side, close to the arms, where they join the disk. Water
flows in and out of these pouches, which are thought to have also
respiratory and excretory functions. No eye-specks have been found,
but they must exist, since the animal is sensible to approaching
danger and quickly retreats. The ophiurans are more active than
starfishes, moving by wriggling, and clambering with their arms. They
are shy and hard to find, and it is difficult to capture a whole one,
since they throw off pieces of their arms at the least alarm. Often
they completely dismember themselves, an action which does them no
permanent injury, since they reproduce lost parts. They are more
commonly inhabitants of deep than of shallow waters, and are brought
up from the bottom in dredges in great numbers. [pg215] Some species
may be found near low-water mark under stones and in clusters of
mussels, and often in seaweeds, thrown up from deep water, on the
shore.
ORDER =EURYALIDA=
GENUS ^Astrophyton^ (Plate LV.)
^A. Agassizii.^ This very singular ophiuran is commonly called the
basket-fish, from its resemblance to a basket when the tentacles
are rolled up. Its body is covered with skin instead of calcareous
plates. The body is thick and somewhat circular in form, with
elevated radiating ridges on the upper side, and the skin is marked
off in star-like divisions. From the margin of the body extend
five arms, which at once divide in a forking manner; each section
again divides, and this division in pairs (dichotomous division)
continues until the ends of the arms have become very numerous and
attenuated. The arms are carried curled up or straight at will. In
moving, the animal seems to walk on these branches as if on tiptoe,
and in this position it forms a kind of net which entraps prey. The
arms and prominent parts of the disk are yellow, and the depressed
or membranous parts brown. /Astrophyton/ is six to eighteen inches
in diameter. It is found off the northern New England coast.
ORDER =OPHIURIDA=
GENUS ^Ophiopholis^
^O. aculeata.^ This is a common species, found in shallow water
on the North Atlantic coast. A similar or perhaps identical
species occurs on the North Pacific coast. It is spotted purple or
variegated in color. The upper surface of the body is covered with
plates variously arranged, sometimes in the shape of a star, and
each one is surrounded with small spines. The under side of the
egg-sacs is covered with small spines. These sacs open by slits on
each side next the arms, and have a rounded appearance, bulging
out between the arms. The arms, which are long and attenuated at
the ends, have on the upper side transverse oval plates surrounded
by a border of flat, roundish granules. Sometimes the plates are
divided into two or three pieces, when they are similarly bordered
with granules. The arms are fringed with rows of thick, compressed,
obtuse spines, generally six in each row. The under sides of the
arms have large quadrangular plates slightly separated from one
another and extending across the whole surface in regular, even
rows. (Plate LV.)
GENUS ^Amphiura^
^A. squamata.^ This very delicate species, found on shelly bottoms
below low-water mark from New Jersey northward, has a body less
than one quarter of an inch in diameter, with arms two inches or
more [pg216] in length and thread-like in size. These long,
slender arms have, on both the upper and under surfaces, a row of
overlapping plates, and are fringed with small spines, three in a
row. The color is gray or whitish, sometimes marked with darker
gray or brown. (Plate LV.)
GENUS ^Ophiocoma^
^O. riisei^, ^O. æthiops^, ^O. Alexandri^. These animals have
long spines on the sides of the arms, which give them a bushy
appearance. The surface of the body is granulated, but the arms
are covered with wide plates. Their color is brown above and light
beneath. /O. riisei/ is found at Key West, the other two species on
the coast of Lower California. (Plate LV.)
GENUS ^Ophiothrix^
^O. angulata.^ Body covered with short, rough spines; egg-sacs
conspicuous and extend like lobes between the arms; rays narrow and
thickly beset with long spines, which are serrated on the edges and
ends. Found on the Florida coast. (Plate LV.)
[Illustration: PLATE LV. Astrophyton. Ophiocoma æthiops Ophiothrix
angulata. Ophiopholis aculeata. Ophiocoma Alexandri. Amphiura
squamata.]
[pg217]
TABLE SHOWING THE CLASSIFICATION OF THE ECHINOIDEA DESCRIBED IN THIS
CHAPTER
=Class= =ECHINOIDEA=
Order =DESMOSTICHA= or =REGULARIA= (/Shell usually globular; mouth
and anus polar; lantern of Aristotle present/)
Families Genera Species
~CIDARIDÆ~ ^Cidaris^ ^C. tribuloides^
^Dorocidaris^ ^D. papillota^
^D. Blakei^
^Porocidaris^ ^P. sharreri^
~ARBACIADÆ~ ^Arbacia^ ^A. punctulata^
^Cœlopleurus^ ^C. floridanus^
~DIADEMATIDÆ~ ^Diadema^ ^D. setosum^
~ECHINOMETRIDÆ~ ^Echinometra^ ^E. subangularis^
^Strongylocentrotus^ ^S. drobachiensis^
^S. purpuratus^
^S. franciscanus^
~ECHINIDÆ~ ^Echinus^ ^E. gracilis^
^Toxopneustes^ ^T. variegatus^
Order =CLYPEASTROIDEA= (/Corona or shell a more or less flattened
disk; anus excentric; lantern of Aristotle present/)
~ECHINANTHIDÆ~ ^Clypeaster^ ^C. ravenellii^
^Echinanthus^ ^E. rosaceus^
~SCUTELLIDÆ~ ^Echinarachnius^ ^E. parma^
^E. excentricus^
^Mellita^ ^M. testudinata^
^Encope^ ^E. michelini^
Order =SPATANGOIDEA= or =PETALOSTICHA= (/Heart-shaped; mouth and
excretory opening excentric; no lantern of Aristotle/)
~SPATANGOIDÆ~ ^Moira^ ^M. atropos^
^Lovenia^ ^L. cordiformis^
^Schizaster^ ^S. fragilis^
^Metalia^ ^M. pectoralis^
^Brissopsis^ ^B. lyrifera^
[pg218]
CLASS =ECHINOIDEA=
SEA-URCHINS, CAKE-URCHINS, HEART-URCHINS
ORDER =DESMOSTICHA=
SEA-URCHINS
The shell of a sea-urchin consists of many calcareous plates,
or /ossicles/, fitted closely together and forming a continuous
exoskeleton. The plates are so united that externally the marks of
juncture are not perceptible, but on the interior the shape of these
plates is well defined. In examining such a shell, or test (they
abound on the beach), it will be seen that its surface is covered
with numerous hemispherical projections or knobs, which are grouped
in double rows and run in meridional lines from one pole to the
other of the more or less spherical body, separating it into ten
divisions. Five of these divisions have perforations, or small pores
in the plates of the shell, and are called the /ambulacral zones/
or areas, because through these pores pass the small tubes, in the
living animal, which connect the tube-feet, or /ambulacra/, with the
radial water-canals and the /ampullæ/ (see page 206). The wide spaces
between these double rows of pores are called the /interambulacral
zones/ or areas. The ten spaces diverge from the /peristome/, or
soft part around the mouth, in the center of the lower surface, and
converge in the small area at the top or aboral side. In the center
of this small circular dorsal space is the excretory opening, and
surrounding it are ten plates, five of which have openings into the
egg-sacs. One of them is larger than the others, and is modified to
form the /madreporic plate/. The other five plates have eye-specks.
The ambulacral zones terminate at these ocular plates.
The numerous spines which cover the animal are of three [pg219]
kinds, and proceed from the knobs on the exoskeleton, over which they
fit, forming ball-and-socket joints, which enable them to move in
any direction. The long spines are ribbed, and seem to have no other
function than that of protection. The second set, the /pedicellariæ/,
are very peculiar small organs scattered over the surface in great
numbers, and consisting of a head bearing three bill-like blades
mounted on a long, flexible stalk. The office of some of the
pedicellariæ is to remove waste from the excretory opening; this is
passed down regular lines and dropped into the water, thus keeping
the body clean. Others are constantly opening and shutting their
forks, reaching in all directions and grasping and removing anything
which may have become entangled in the spines. They also capture
floating bits of seaweed, which they drag over the body to conceal
it. A third set of projections are the /sphæridia/, small globular
bodies said to be connected with perception.
[Illustration: Test of sea-urchin, with the spines removed to show
the arrangement of the plates, lateral view: /Amb/, ambulacral zone
with its perforated plates; /Ap/, apical (aboral) pole; /Int. amb./,
interambulacral zones. (From Bronn's "Thierreich.")]
The spines vary greatly in size, number, and form in different
species, and are such conspicuous features as to make the
identification of species easy. In some the spines are solid and
fluted; [pg220] in others they are hollow, sharp, and brittle; again
in others they are short and silky, or very long and serrated, and so
on. In one species they are so broad and flat as to resemble little
sails. (See /Dorocidaris/.) (Plate LVI.)
The mouth, over which five long teeth project, is a part of
Aristotle's lantern, which forms a curious and prominent feature in
the center of the lower surface. Ten tentacles, like large tube-feet
without suckers, lie around the mouth. The alimentary canal, starting
in Aristotle's lantern, winds in two and a half coils around the
inside of the shell, supported by mesenteries, and terminates in the
excretory opening on the aboral surface. The sea-urchin has also
a water-vascular system similar to that of starfishes (page 206).
When the tube-feet are distended they project beyond the spines, and
enable the animal to move slowly about; but sea-urchins are less
active than starfishes, and although they are so well protected by
spines and have few enemies after maturity, they lie in sluggish
idleness in secluded places, and for further concealment often cover
themselves with seaweeds or stones.
The sea-urchin has a nervous system, which starts in a ring around
the mouth, ramifies through the body, and terminates in the
eye-plates. The tube-feet and all the spines are under nervous as
well as muscular control. Egg-sacs lie under the apex of the shell
and open by separate ducts into the five plates on the small upper
disk. Through these the eggs are discharged into the water, where
they become free-swimming larvæ, called /Pluteus/. This immature
sea-urchin (Pluteus) undergoes several curious transformations in
the course of its development, and does not in any way resemble the
mature animal. In spring the apical disk of the females will often
be found covered with orange-colored ova, and that of the males with
white sperms. In the growth of the animal, in its mature form, the
shell enlarges by accretions of lime on the individual plates, or
ossicles, of the exoskeleton, and by new plates formed around the
apical disk. Sea-urchins are compared to starfishes folded over, the
eye-specks on the ends of the rays meeting in a small area around
the excretory opening, the ambulacra following spherical lines and
leaving the mouth, as before, on the ventral side. [pg221]
The /Echinoidea/ present great differences in shape, being more or
less spherical, oval, discoid, and heart-shaped. These variations are
associated with the differences of internal structure, the openings
of the digestive tract being at the opposite poles in the spherical
and oval forms, but excentric in the disk- and heart-shaped species.
The sea-urchins are grouped in three orders in accordance with these
variations. All are characterized by the absence of arms, by having
the calcareous plates immovably united to form a firm test, and by
the great development of the movable spines upon the plates.
Sea-urchins are sometimes called /sea-eggs/, perhaps from their
shape, but possibly from the edible quality of some species, which
are eaten by the natives of the shore, who take them at the spawning
season, when the egg-sacs are distended. They are gregarious, and
frequently are so crowded together as literally to pave the surface
of rocks and the bottoms of tide-pools in sheltered places. The
following is quoted from A. Agassiz: "Many of the /Desmosticha/
along coasts exposed to the action of the waves live in cavities
which they hollow out of the solid rock. This they do, not by means
of any solvent, but by mere mechanical action. They chisel out with
their teeth the solid rock by incessant turning round and round, and
keep their cave, where they are frequently prisoners for the rest
of their existence, up to the size required by the growth of their
test and spines, by constant gnawing. On the coast of California the
common /Strongylocentrotus purpuratus/ occurs in this way. We find
long tracts of shore, where this sea-urchin is common, completely
honeycombed and pitted by cavities and depressions in which they seek
shelter against the powerful surf continually beating against the
rocks. The same species does not excavate in sheltered places, where
the sea-urchins can find protection between the interstices of large
fragments of rock or ledges more or less sheltered from the more
direct action of the open sea."
Sea-urchins in cavities of granite rock, where the openings are too
small for the animal to get out, are to be seen in thousands on the
coast of France at Croisic, Lower Loire. Spines of large sea-urchins
are used as slate-pencils by the missionaries in the Pacific
Islands. [pg222]
FAMILY ~CIDARIDÆ~
GENUS ^Cidaris^
^C. tribuloides.^ Similar to /Porocidaris sharreri/, but with
thicker and stouter spines. Found from South Carolina to Brazil.
GENUS ^Dorocidaris^
^D. papillota.^ A deep-water species which occurs off Chesapeake
Bay and southward. It has slender spines with distinct longitudinal
rows of serrations, and the spines are grouped in rosette-like
forms over the small spherical body.
^D. Blakei.^ This species is very peculiar in having broad,
fan-shaped spines; vermilion in color. Found in deep water in the
Bahamas and West Indies. (Plate LVII.)
GENUS ^Porocidaris^
^P. sharreri.^ This species occurs, in deep water, off the coast of
North Carolina and thence southward to the West Indies. The shell
is light greenish-pink. The spines are white, with brownish-pink
at the base, pointed, three and a half inches long, and surrounded
at the base with small, flat, triangular, secondary spines. (Plate
LVII.)
FAMILY ~ARBACIADÆ~
GENUS ^Arbacia^
^A. punctulata.^ A small species found in shallow water on shelly
and gravelly bottoms from Massachusetts to Mexico, and common
in Long Island Sound. The shell is about one inch in diameter;
the spines are rather thick and one half to three quarters of an
inch long. The color varies from deep violet—almost black—to
straw-color, and the spines are tipped with brown. The South
Carolina species are usually brick-red in the bare interambulacral
spaces, with darker sutures, and spines tipped with same color. The
animal walks by means of its spines, with a tilting motion, and
advances quite rapidly. (Plate LVII.)
GENUS ^Cœlopleurus^
^C. floridanus.^ This beautiful sea-urchin is taken on the Florida
reefs. The very brittle spines are one to four inches long, and
are banded with carmine and white. The shell has zones of light
chocolate-color alternating with orange and yellow.
FAMILY ~DIADEMATIDÆ~
GENUS ^Diadema^
^D. setosum.^ Spines very brittle, and from one to two and a half
inches long; jet-black. Found on the Florida reefs. (Plate LVII.)
[Illustration: PLATE LVI. Pedicellariæ of sea-urchins. Spines of
sea-urchins.]
[Illustration: PLATE LVII. Porocidaris sharreri. Dorocidaris
Blakei. Arbacia punctulata. Diadema setosum. Strongylocentrotus
franciscanus.]
FAMILY ~ECHINOMETRIDÆ~
In this family the ambulacral plates have several pairs of pores.
GENUS ^Echinometra^
^E. subangularis.^ This species, which ranges from South Carolina
to Brazil, and is also found in Bermuda, is common on mud-flats
and is easily distinguished by its oblong or elliptical shape.
Its shell is about three inches long in its widest portion. The
spines are one half of an inch to one inch long, thick at the base
and tapering to a point. The color is dark purplish-green to deep
violet—almost black.
GENUS ^Strongylocentrotus^
^S. drobachiensis.^ This sea-urchin (which bears, perhaps, the
longest name in technical nomenclature and has no other, unless
that of "sea-egg," which is applied indiscriminately to all
sea-urchins) is a very common species in shallow waters of the
northern temperate zones. It extends as far as New Jersey on the
Atlantic and to the State of Washington on the Pacific coast.
Although it is found as far south as New Jersey, it is there rare
and small; but farther north, especially on the coast of Maine,
it is exceedingly abundant. It is green or greenish-purple in
color, and resembles somewhat a large chestnut-bur. The body is
circular, somewhat depressed (but of variable thickness), and
about two inches in diameter. The spines are moderately slender
and longitudinally striated. It feeds partly on diatoms and other
small algæ, which it cuts from the rocks with its sharp teeth. It
also devours dead fishes, bones and all, and in return is swallowed
whole by the wolffish and other large fishes. It moves by means
of the tube-feet on its oral surface, slowly dragging itself
along, and frequently is seen with seaweed, a stone, or some other
substance on its back, which it places there with its pedicellariæ
for the purpose of concealment.
^S. purpuratus.^ The common purple sea-urchin of the west coast,
from Sitka to Lower California, found in abundance on the rocks
just beyond low-water mark. It is about one and a half inches in
diameter, with rather thick, pointed, and fluted spines.
^S. franciscanus.^ This is the largest species of the west coast,
the shell measuring sometimes five inches across, and the thick
spines one and a half inches in length. The tubercles on the naked
shells are very prominent, and the zones are very clearly marked.
It is purple in color and is often found in great quantities at
low-water mark. It ranges from Alaska to Lower California. (Plate
LVII.)
FAMILY ~ECHINIDÆ~
In this family the ambulacral plates have but three pairs of pores.
[pg224]
GENUS ^Echinus^
^E. gracilis.^ This is a deep-water species, which occurs from
Cape Cod southward. The shell is nearly spherical, but is a
little depressed on the oral side, and has twenty bands of color,
alternately green and white. The spines are short and thin.
GENUS ^Toxopneustes^
^T. variegatus.^ This is the common species of the Southern States,
from North Carolina southward, and is found in shallow water in
protected places. The shell is nearly globular; the spines vary in
thickness and color, some being long, slender, and greenish, while
others have stout and blunt spines of a yellowish or violet tint.
ORDER =CLYPEASTROIDEA=
CAKE-URCHINS
The animals of this order, commonly known as sand-cakes or
sand-dollars, are flat and circular like disks. Sometimes they are
cut at intervals on the margin; again they have slits through the
body (/lunules/). They have a well-marked star-shaped figure on the
dorsal surface. This figure is formed by the ambulacra, or tube-feet,
which run in five rounded or petal-shaped lines on the under surface.
The mouth, in Aristotle's lantern, is in the center of the somewhat
concave ventral surface, the petal-like ambulacral zones meeting at
the central space. The excretory opening is on the margin of the
disk, at a point between two of the sections of the star-like figure.
This marks the posterior part of the body, while the opposite arm
of the star marks the front or anterior end. The spines are very
fine and silky, and are spread abundantly over the whole animal.
Clypeasteroids are mainly found in sand considerably below low-water
mark, though some species thrive where they are exposed to the surf
on open sandy beaches.
FAMILY ~ECHINANTHIDÆ~
GENUS ^Clypeaster^
^C. ravenellii.^ This species occurs in deep water from South
Carolina southward. The disk is about four inches in diameter,
and is raised [pg225] in the center into a large cone. The
ambulacra run down the sides of the cone in straight lines, and
around the base is a depressed area which emphasizes a thick border
which extends around the scalloped margin. The color is light
yellowish-brown. (Plate LVIII.)
GENUS ^Echinanthus^
^E. rosaceus.^ This is a large species, oblong in shape, about
four to five inches across and much rounded on top, the body being
about two inches thick. The ambulacral zones are depressed, leaving
prominent elevations which make a very conspicuous figure on the
top. The color is light chocolate-brown. Found close to the shore
off the coasts of Florida, South Carolina, and the West Indies.
FAMILY ~SCUTELLIDÆ~
GENUS ^Echinarachnius^
THE SAND-DOLLARS
^E. parma.^ This species, the shells of which are very common
objects on sand-beaches from New Jersey northward, is generally
known as the sand-dollar. The animals have flat circular disks
about three inches in diameter. The ambulacral zones, in five
petal-like lines, form a distinct figure on the upper surface. The
mouth is in the center of the ventral surface, and the excretory
opening is on the edge of the disk. In life they are covered
with short, fine, silky spines, which seem like hair, and are
purplish-brown in color, but turn green when taken from the water.
The sand-dollars are exceedingly abundant off Nantucket Shoals,
where the bottom seems paved with them. They are eaten in great
numbers by flounders, cod, and haddock. When put in alcohol they
stain it a dark color. Fishermen prepare an indelible ink by
grinding to powder these animals and mixing it with some liquid.
This species is also found on the northern Pacific coast.
[Illustration: /Echinarachnius parma/, the sand-dollar. Much
smaller than natural size.]
^E. excentricus.^ This is the common sand-dollar of the Pacific
coast. The disk, instead of being circular as in /E. parma/, is
somewhat straight across the posterior end, and the posterior
ambulacral zones are shorter than the other three. The upper side
of the disk is raised, forming a cone-like elevation, the apex
being the center of the figure.
GENUS ^Mellita^
^M. testudinata.^ The disk is rounded in front and straight in the
back. Four long, narrow lunules, or cuts, occur on the sides in
line with the ambulacral, petal-shaped zones, but do not extend
quite to the edge of the disk; and a wide lunule occurs in the
interambulacral space [pg226] of the posterior end. The three
anterior zones are shorter than the posterior pair. On the upper
side of the disk the spines all turn toward the periphery. The
color of the living animal is greenish-blue. It is very abundant
from Cape Hatteras southward in shallow water, and the shells are
sometimes found as far north as Cape Cod. (Plate LVIII.)
GENUS ^Encope^
^E. michelini.^ Ambulacral zones unequal in size, the posterior
pair usually longer than the others; lunules like notches in the
margin, with a large one opening between the posterior ambulacral
zones nearly in the center of the disk; disk rounded in front and
square at the back. Common on the coasts of southern Florida and
the Gulf of Mexico in shallow water. (Plate LVIII.)
ORDER =SPATANGOIDEA=
HEART-URCHINS
The /Spatangoidea/, or heart-urchins, have heart-shaped or thick
elliptical bodies. The mouth and excretory opening are both away from
the center and on the ventral side. These animals seem deformed, so
much are they out of symmetry and so different in outline from the
other orders of the class. The ambulacral zones are in circles, or
petaloid in outline, as in cake-urchins, but are not continuous, and
the anterior one is usually unlike the others and frequently without
pores. The entire body is covered with spines, and these are the
chief organs of locomotion; the greater part of them turn backward,
giving the living animal the semblance of a porcupine. The mouth is
protected by a projecting plate, but Aristotle's lantern is absent
in this order. The anatomy is in general the same as in the other
orders, but the organs are turned in conformity with the inclosing
shell. Most of these animals bury themselves in sand or mud and live
in deep water; a few only are littoral species.
FAMILY ~SPATANGOIDÆ~
GENUS =Moira=
^M. atropos.^ Size about one inch by one and a half inches, and one
inch thick; color yellowish-white, with brown spines. Found from
North Carolina to Florida, from the shore to deep water.
[Illustration: PLATE LVIII. Clypeaster ravenellii. Mellita
testudinata. Encope michelini. Test of Metalia pectoralis. Lovenia
cordiformis.]
[pg227]
GENUS ^Lovenia^
^L. cordiformis.^ About one inch by one and a half inches thick;
reddish in color; resembles a little porcupine. Found on the
southern California coast. (Plate LVIII.)
GENUS ^Schizaster^
^S. fragilis.^ One and a half by two inches in size, and one inch
thick; color brownish. Lives in deep water off the eastern coast.
GENUS =Metalia=
^M. pectoralis.^ A very large heart-urchin, found on the southern
coast of Florida and in the West Indies in shallow water. It is,
perhaps, the largest species found, being six to eight inches long
and proportionately wide and thick. The shell is thin, more or less
elliptical, and densely clothed with long reddish-gray spines.
(Plate LVIII.)
GENUS ^Brissopsis^
^B. lyrifera.^ A beautiful deep-water species, found off the
coasts of Florida and the Gulf of Mexico. It has a red body with
pale-yellowish spines. In size it is about two by two and a half
inches, and is thickest on the posterior end. It is thickly clothed
with long curved spines, some of which form two long tufts in the
back. [pg228]
TABLE SHOWING THE CLASSIFICATION OF THE HOLOTHUROIDEA DESCRIBED IN
THIS CHAPTER
Class =HOLOTHUROIDEA=
Order =ELASIPODA= (/Deep-sea forms; tube-feet in zones near
together/)
Order =PEDATA= (/Well-developed tube-feet and false ambulacra/)
Genera Species
^Thyone^ ^T. briareus^
^Pentacta^ ^P. frondosa^
^Lophothuria^ ^L. fabricii^
Order =APODA= (/Without radial canals, tube-feet, or respiratory
trees/)
^Synapta^ ^S. tenuis^
^S. roseola^
^S. rotifera^
^Caudina^ ^C. arenata^
[pg229]
CLASS =HOLOTHUROIDEA=
SEA-CUCUMBERS
The holothurians, or sea-cucumbers, although in appearance quite
unlike starfishes and sea-urchins, have the characteristic ambulacral
zones and other features of the group. In form they are cylindrical,
and, when the tentacles and tube-feet are retracted, resemble fat
worms; when fully expanded they are somewhat like sea-anemones, the
tentacles forming a rosette-like top. The walls of the body are tough
and muscular, with small calcareous deposits or spicules of various
shapes in the skin. The mouth is at one end, the excretory opening
at the other, and along the body are double rows of tube-feet. Often
instead of tube-feet, or together with them, are conical processes
without suckers. The ambulacra, when arranged in regular zones, are
used for locomotion only in the lines running from the madreporic
plate. In some species three of the zones are near together, and form
a kind of sole on which the animal creeps; again the tube-feet are
wholly suppressed, as in /Synapta/. Besides progressing by means of
these suckers, the holothurians move, as do worms, by the extension
and contraction of the body. The inner surface of the tough membrane
inclosing the body is lined with powerful longitudinal and transverse
muscles, by means of which the creature contracts and lengthens its
body and changes its form in a wonderful manner. Around the mouth
are tentacles, which are often much branched and are used as organs
of touch and smell, and sometimes have an ear-sac at the base. From
the mouth the food-canal, making one long coil, extends to a chamber
[pg231] (/cloaca/) at the other pole. The cloaca gives off a pair
of much-branched respiratory trees, which are constantly supplied
with water by the contractions of the cloaca. At the base of one of
the respiratory trees are singular structures known as /Cuvierian
organs/. They are numerous, viscid, glandular tubes, which the animal
can throw out, and which will adhere closely to almost anything. The
holothurian has a water-vascular system, the madreporic plate being
near the mouth, but not opening to the outside, and a nervous system
which starts from a ring which lies around the mouth. The egg-sacs
are branched tubes, often highly colored, which open to the outside,
close to the wreath of tentacles surrounding the mouth.
[Illustration: Internal organs of a /Holothurian/, as seen when
the body-wall is divided along the middle of the dorsal surface:
/b.w./, body-wall; /circ. mus./, circular layer of muscle; /cl./,
cloaca; /cl. op./, cloacal opening with five teeth; /cuv. org./,
Cuvierian organs; /gen. ap./, genital aperture; /gen. du./, genital
duct; /gen. gl./, genital gland; /int./, intestine; /inter. oss./,
interambulacral ossicles; /int. ves./, intestinal vessels; /long.
mus./, longitudinal band of muscle; /mad. can./, madreporic canals;
/mes./, mesentery; /pol. ves./, Polian vesicles; /rad. amb./, radial
ambulacral vessel; /ri. bl. ves./, ring blood-vessel; /resp./,
respiratory trees; /ring-ves./, ring-vessel of the ambulacral system;
/stom./, stomach.]
The larvæ, when free-swimming, are called /Auricula/. In the
deep-water species, /Cucumaria crocea/ and /Psolus ephippiger/, the
eggs, when discharged, and the young are carried on the back of the
mother. In /Cucumaria lævigata/ there is a brood-pouch, while in
/Synapta viviparia/ the young develop in the body-cavity.
The holothurians have the singular power of ejecting the whole of
their internal organs and of growing them again in case they escape
the enemy they have endeavored to elude by this strange method. They
also turn themselves inside out, as it were, as if from /nausea/,
when confined in water too stale for their uses. Often the viscera
are ejected through holes in the sides of the body broken by violent
muscular contractions.
Holothurians are generally distributed through all seas, but are
congregated in greatest numbers in Eastern seas. Their habitat
extends from shallow to very deep water. They are found in
tide-pools, on rocks, and in sand or mud. Like worms, they live on
organic particles contained in mud and sand, which they take into the
gullet and pass through the alimentary canal.
ORDER =PEDATA=
GENUS ^Thyone^
^T. briareus.^ This is a large purple holothurian, found in shallow
water from Texas to Cape Cod. It is four to five inches long and
one inch or more thick, purple in color, and thickly covered over
its whole surface with prominent papillæ. [pg232]
GENUS ^Pentacta^
[Illustration: /Pentacta frondosa/, the sea-cucumber.]
^P. frondosa.^ This animal is commonly called the sea-cucumber,
and the popular name somewhat expresses its form, but it has the
power of changing its shape in a most surprising manner. Sometimes
it will be nearly globular, again long and thin, or it may be
constricted like an hourglass. When at rest the body is ovate and
somewhat pentagonal. On the angles are double lines of suckers, and
in the interambulacral zones are a few scattered false ambulacra.
The surface is nearly smooth, very dark purple on one side, and
inclined to whitish on the other. Ten much-branched tentacles
surround the mouth. The animal, when grown and expanded, measures
fifteen to eighteen inches in length. This species is found
throughout the whole length of both the east and the west coasts.
It is very plentiful on the Maine coast in tide-pools and on the
rocks at low-water mark. The genus ranges over the greater part of
the globe. The tough muscular body is said to be edible, tasting
somewhat like lobster, or trepang (/Holothuria edulis/), which is
found on coral reefs in Eastern seas and is much valued as food
by the Chinese. The internal organs of /P. frondosa/ are highly
colored, making its anatomy easy to trace. The muscular system is
plainly defined.
GENUS ^Lophothuria^
[Illustration: /Lophothuria fabricii/, showing under surface with
three rows of ambulacra.]
^L. fabricii^ (Verrill), ^Psolus fabricii^ (Düben), ^Cuvieria
squamata^ (D. and K.: Agassiz). The body in this species is covered
with rounded overlapping scales and numerous granulations, and
when it is retracted is about two and a half to three inches long
and about one inch thick. [pg233] Rows of tube-feet lie near
together, on a flat under surface, and form a kind of sole on which
the animal creeps. The oral end of the body is a little raised
and bears ten tentacles; these tentacles are profusely and finely
branched, and when expanded are about as long as the body. The
aboral end is obtuse and a little raised. Around the oral and anal
openings the scales are grouped, forming circles in those regions.
This holothurian is bright red in color, and when expanded is a
beautiful object, perhaps the most attractive in appearance of any
in the class. When retracted it has the aspect of an ascidian, and
for a time was supposed to belong to that group. It is found on the
New England coast on the under side of large shelving rocks.
ORDER =APODA=
GENUS ^Synapta^
^S. tenuis.^ This curious animal is long and slender, and so
transparent that its internal organs are clearly visible. Around
the mouth are a circular tube and a wreath of twelve branching
tentacles. There are no ambulacra. Little spots scattered
irregularly over the surface show, when highly magnified, small
warts, each one of which has a calcareous projection shaped like a
little anchor. By means of these anchors and by the contractions
of its body the animal moves through the mud or sand in which it
lives, near low-water mark. The sand is collected into rings at the
oral end and pushed downward until the whole animal is inclosed in
a sand-tube. When empty /Synapta/ is white and transparent, and
the digestive canal may be seen wound in a spiral throughout its
length; but when gorged with food, sand, pebbles, and shells can
be distinctly seen filling the food-canal, and the body then has a
dark-gray color. /Synapta/ grows to a length of eighteen inches or
more, but is constantly breaking pieces off its posterior end by
muscular contractions. When kept in confinement it soon commences
to constrict its body at various points, and after a few hours
there is nothing left but a mass of fragments. It is viviparous,
that is, it carries its young in the body-cavity; the eggs are
hatched, and the young approach maturity before they are expelled.
This species ranges from Cape Cod to North Carolina, and can be
found in the upper part of its burrows when the tide is out.
^S. roseola.^ This species occurs in the same localities as /S.
tenuis/, and differs from it mainly in color, which is pale red,
due to minute red spots scattered through the skin.
^S. rotifera.^ A species found in Florida. It is light purplish
in color, and has eight or ten branches on each of the twelve
tentacles. In this species the spicules of lime in the skin are
shaped like wheels instead of anchors.
GENUS ^Caudina^
^C. arenata.^ About four inches long and tapers to the ends; the
posterior end sometimes narrowed to a long, slender, tail-like
extremity; tentacles around the mouth resemble cloves. It lives in
sand and may be found on the New England coast, washed ashore after
a storm. [pg234]
Class =CRINOIDEA=
Genera ^Pentacrinus^ ^Comatula^
CLASS =CRINOIDEA=
FEATHER-STARS AND SEA-LILIES
[Illustration: The feather-star (/Antedon/), illustrating the
/Comatula/ form of crinoid.]
The crinoids are inhabitants of deep water, where they grow in great
numbers, forming beds of sea-lilies. Their general form, which
suggests the lily, and their feather-like manner of branching, give
them the two common names of sea-lilies and sea-feathers. They have
a long, jointed stalk, one end of which is attached, while the other
bears the disk of the animal. From the disk emanate five arms, which
divide near the base, making [pg235] ten arms in all. The arms
have short branches along the sides. Ambulacral grooves follow the
center of all the arms and branches. The mouth is in the center of
the upper side, which in this case is the ventral surface. The genus
^Pentacrinus^ remains permanently attached, but ^Comatula^, at a
certain stage of development, separates from the stalk and swims
freely about by means of its arms. It can attach itself temporarily
by tubular processes, which are developed on the dorsal surface at
the point where the stem was attached. The ossicles, or plates which
cover the dorsal surface, are free, making the crinoid an animal of
innumerable joints.
[Illustration: /Pentacrinus asteria./]
The crinoids are particularly interesting from the fact that they
have existed from early geologic times, and their history is written
in stone. In the early ages they were the only class of echinoderms,
and their evolution into other forms can be traced through successive
geologic periods. They existed in such vast numbers that the fossil
forms are plentiful and are familiar to every student of geology, and
are known as stone-lilies and encrinites. To-day they are decadent,
there now remaining only twelve of the two hundred genera which
existed formerly. A fine bed of crinoids is found off Cuba, on the
slope of the coast where the water rapidly deepens from one hundred
to two hundred fathoms. [pg236]
Although the crinoids are deep-water forms, and are never found on
the beach, they are given here because they follow in the system of
classification and illustrate another curious class of echinoderms.
The brief description given may add interest to the fossil forms to
be seen in museums.
VI
ARTHROPODA
TABLE SHOWING THE CLASSIFICATION OF THE ARTHROPODS DESCRIBED IN THIS
CHAPTER
Phylum =ARTHROPODA=
Class =CRUSTACEA=
Subclass =Entomostraca= (/Crustacea of small, often of almost
microscopic minuteness, and of comparatively simple
organization; appendages have little differentiation/)
Order =PHYLLOPODA= (/Appendages resemble leaves; mostly
fresh-water species/)
Suborder ~EUPHYLLOPODA~ (/Phyllopoda of considerable
size, bearing ten to sixty pairs of leaf-like
swimming-feet/)
Suborder ~CLADOCERA~ (/Small phyllopoda; body laterally
compressed; carapace like a bivalve shell; four to five
pairs of swimming-feet; chief organs of locomotion are
the biramous antennæ; abdomen devoid of appendages. They
abound in fresh water, are very prolific, and afford a
large amount of food to fresh-water fishes/)
Genera Species
^Daphnia^
^Leptodora^
^Moina^
^Polyphemus^
Order =OSTRACODA= (/Resemble minute bivalve shells; swim by
antennæ; body unsegmented; appendages seven pairs only/)
^Cypris^ (fresh-water)
^Cypridina^ (marine)
Order =COPEPODA= (/Small size; body long, segmented; four to
five pairs of once-branched appendages on thorax; abdomen
without appendages; abundant in fresh and salt water; many
forms parasitic/)
^Cyclops^
^Cetochilus^
^Sapphirina^
^Siphonostomata^
^Nicothoë^
Order =CIRRIPEDIA= (/Imperfectly segmented; fixed or
parasitic during adult life; inclosed in skin strengthened
by calcareous plates; abdomen rudimentary; appendages
biramous, usually six pairs/)
Genera Species
^Lepas^ ^L. anatifera^
^L. striata^
^L. pectinata^
^Balanus^ ^B. balanoides^
^B. eburneus^
^B. rugosus^
^B. geniculatus^
^B. tintinnabulum^
Suborder ~RHIZOCEPHALA~ (/Parasitic/.)
^Sacculina^ (parasitic on crabs)
^Peltogaster^ (parasitic on hermit-crabs)
Subclass =Malacostraca= (/Highly organized Crustacea, usually
of considerable size; appendages much differentiated/)
Order =PHYLLOCARIDA= (/Small; covered with bivalved carapace;
thoracic feet leaf-like; abdominal feet biramous; posterior
segment terminates in two long spines; mostly fresh-water
species/)
Order =SCHIZOPODA= (/Small; transparent; shrimp-like; thorax
more or less completely covered with soft carapace;
thoracic appendages biramous; eyes on stalks/. /Mysis/ are
/Without gills or thoracic legs/; /Euphausia/ are /With
gills or thoracic legs/.)
^Mysis^ ^M. sternolepis^
^Euphausia^
Order =DECAPODA= (/Thoracic segments unite with head and form
cephalothorax, which is covered by carapace; eyes stalked;
maxillipeds have exopodites; five pairs of walking-feet
without exopodites/)
Suborder ~MACRURA~ (/Abdomen usually longer than
cephalothorax and commonly extended; rostrum usually
prominent; eyes not inclosed in orbits; antennæ and
antennules large; antennæ have exopodites/)
Set Free-swimming Forms: Shrimps and Prawns
^Penæus^ ^P. setiferus^
^P. brasiliensis^
^Palæmonetes^ ^P. vulgaris^
^Crangon^ ^C. vulgaris^
^C. franciscorum^
Families Genera Species
Set Creeping Forms: Lobsters and Crawfish
ASTACOIDÆ ^Homarus^ ^H. americanus^
^Panulirus^ ^P. interruptus^
^P. argus^
^Scyllarus^
Set Anomalous Forms: Approaching the Brachyura
Suborder ~ANOMURA~ (Of these Families, the Lithodidæ have
/Fifth pair of feet folded under the carapace/)
DROMIDÆ ^Hippoconcha^ ^H. arcuata^
PAGURIDÆ ^Pagurus^ ^P. bernhardus^
^P. pollicaris^
^P. longicarpus^
^Clibanarius^ ^C. vittatus^
^Pylopagurus^
CENOBITIDÆ ^Cenobita^ ^C. diogenes^
HIPPIDÆ ^Hippa^ ^H. talpoida^
^H. analoga^
^Albunæa^ ^A. gibbesii^
PORCELLANIDÆ ^Porcellana^ ^P. sayana^
^P. sexspinosus^
^Petrolisthes^ ^P. armatus^
LITHODIDÆ ^Lithodes^ ^L. maia^
^Echidnocerus^ ^E. cibarius^
^E. foriminatus^
^Acantholithodes^ ^A. hispidus^
^Cryptolithodes^ ^C. sitchensis^
^Phyllolithodes^ ^P. papillosus^
Suborder =BRACHYURA= (/Abdomen shorter than cephalothorax,
and permanently folded under it; eyes inclosed in orbits;
antennules and antennæ small/. Of these Families, the
PORTUNIDÆ are called /Swimming crabs/; the OCYPODIDÆ are
called /Sand- and fiddler-crabs/; and the MAIIDÆ are the
so-called /Spider-crabs/.)
Families Genera Species
PORTUNIDÆ ^Carcinides^ ^C. mænas^
^Callinectes^ ^C. sapidus^
^Ovalipes^ ^O. ocellatus^
Set WALKING CRABS
CANCROIDÆ ^Cancer^ ^C. irroratus^
^C. borealis^
^C. magister^
^C. productus^
^C. antennarius^
^Menippe^ ^M. mercenaria^
^Eupanopeus^ ^E. herbstii^
^Eurypanopeus^ ^E. depressus^
^Neopanopeus^ ^N. texana^
^Rhithropanopeus^ ^R. harrisii^
GRAPSIDÆ ^Hemigrapsus^ ^H. nudus^
^H. oregonensis^
^Pacygrapsus^ ^P. crassipes^
OCYPODIDÆ ^Ocypoda^ ^O. arenaria^
^Uca^ ^U. minax^
^U. pugnax^
^U. pugilator^
MAIIDÆ ^Libinia^ ^L. dubia^
^L. emarginata^
^Hyas^ ^H. coarctatus^
^H. lyratus^
^H. araneus^
^Loxorhynchus^ ^L. crispatus^
^Pugettia^ ^P. gracilis^
^Sternorhynchus^ ^S. sagittarius^
^Epialtus^ ^E. productus^
^Pitho^ ^P. aculeata^
^Lambrus^ ^L. pourtalesii^
CALAPPIDÆ ^Calappa^ ^C. flamma^
PINNOTHERIIDÆ ^Pinnotheres^ ^P. ostreum^
Order =STOMATOPODA= (/Abdomen very large; second pair
of thoracic legs very large; gills borne on abdominal
segments/)
^Squilla^ ^S. empusa^
Order =CUMACEA= (/Small, shrimp-like/)
^Diastylis^ ^D. quadrispinosus^
Order =ARTHROSTRACA= (/No carapace, as a rule; six to seven
pairs of walking-legs; eyes sessile/)
Suborder ~AMPHIPODA~ (/Body usually compressed laterally/)
^Orchestia^ ^O. agilis^
^Talorchestia^ ^T. longicornis^
^Gammarus^ ^G. locusta^
^Chelura^ ^C. terebrans^
^Caprella^ ^C. geometrica^
Suborder ~ISOPODA~ (/Body depressed or flattened/)
^Cirolana^ ^C. concharum^
^Limnoria^ ^L. lignorum^
^Sphæroma^ ^S. quadridentatum^
^Idotea^ ^I. marina^
^I. ochotensis^
^I. metallica^
^I. wosnesenskii^
^Chiridotea^ ^C. cæca^
^C. entomon^
Class =MERISTOMES=
Order =XIPHOSURA=
^Limulus^ ^L. polyphemus^
Class =PANTOPODA= (Lang)
Order =PYCNOGONIDA=
^Phoxichilidium^ ^P. maxillare^
[pg243]
TERMS USED IN DESCRIBING CRUSTACEA
^Abdomen^: The posterior part of the body.
^Antennæ^: Articulated appendages which immediately precede the mouth.
^Anten´nules^: The anterior of the two pairs of feelers of the head.
^Bira´mous^: Having two branches.
^Carapace^: A thin chitinous shell covering the cephalothorax.
^Cephalic^: Pertaining to the head.
^Cephalotho´rax^: The united head and thorax.
^Chela^: The pair of pincers, or claw, which terminates some of the
appendages.
^Che´liped^: A leg with chela, or claw, at the end.
^Endop´odite^: The inner one of the two main divisions of the limb.
^Epime´ra^: Divisions on the ends of the segments of amphipods and
isopods, and belonging to the legs.
^Epip´odite^: A third branch of a limb.
^Epis´toma^: A triangular area in front of the mouth.
^Exop´odite^: The outer one of the two main branches into which the
typical limb of any segment is divided.
^Gastric mill^: The first half of the stomach, where food is ground.
^Mandibles^: The pair of appendages next behind the antennæ.
^Maxil´læ^: The first pair of appendages after the mandibles.
^Maxillipeds^: The three pairs of appendages after the maxillæ.
^Metame´res^: Segments.
^Orbits^: Eye-cavities, peculiar to the higher /Crustacea/.
^Prosto´mium^: The region in front of the mouth; the preoral part of
the head.
^Rostrum^: The beak in front of the head.
^Segment^: A part cut off or marked as separate from others.
^Somite^: A segment of the body.
^Squame^: A scale.
^Telson^: The last segment of the abdomen.
^Thorax^: The middle part of the body.
[pg244]
ARTHROPODA
This subdivision of the animal kingdom includes insects, centipedes,
spiders, and crustaceans, which together constitute more than
half the known species of animals. Although these animals are so
unlike in general appearance, it is easy to recognize the common
characteristics which place them together in one group. The name
/Arthropoda/, meaning "jointed-footed," suggests perhaps one of the
most obvious points of resemblance. The /Arthropoda/ have bilateral
symmetry, one side of the body being like the other; they are covered
with a horn-like material (chitin); they are divided into segments;
the segments have appendages; and the appendages are jointed so as
to admit freedom of motion. Their manner of growth is peculiar; they
cast off their rigid external coverings and secrete larger coats of
mail, and at these periods increase in size or undergo metamorphosis.
There are such modifications of these general features as the habits
of the different species demand. For instance, the appendages may be
constructed for walking, swimming, boring, sucking, or the seizure
and preparation of food. In some animals the appendages form a part
of the breathing-organs, in others are used as organs of sense. Every
detail of the organism, down to the hairs, has its special use and
function.
CLASS =CRUSTACEA=
The crustaceans vary in size from microscopic minuteness to two feet
or more in length. The giant crab of Japan (/Kaempferia kaempferi/)
exceeds this, being commonly from eight to twelve feet [pg245]
across the arms, and is said to reach even greater proportions.
Crustaceans live on land and sea, and in both fresh and salt water;
they may be parasitic, sedentary, or free and active. There are said
to be over ten thousand species, which include crabs, lobsters,
shrimps, beach-fleas, wood-lice, barnacles, and water-fleas. Nine
tenths of the species are marine; of these some are pelagic, and
their transparent forms constitute a part of the plankton. Others
live on the bottom in deep water and attain a large size. A vast
number live in the littoral zone and form a considerable part of that
crowded community. They are scavengers and freebooters, being great
fighters, as well as predatory in their habits. As a rule, they feed
on dead organic matter, which they consume in surprising quantities;
some have also a vegetarian diet. They have, like starfishes, the
singular power of throwing off their limbs and growing new ones.
The /Crustacea/ derive their name from the nature of their crust or
covering. This is earthy and brittle, not stony, like the shells
of mollusks. This crust, or exoskeleton, has various degrees of
firmness, from that of a delicate polished cuticle, seen in small
forms, to the heavy armor of some crabs and the shell-like character
of the covering of barnacles.
The lobster and crab are perhaps the most comprehensive examples as
well as the largest in size of the class, the vast majority of the
species being minute forms. The ocean swarms with varieties too small
to be noticeable to the naked eye.
It is the province of /Crustacea/ to consume decaying organic matter,
both animal and vegetable, and in doing this they perform a great
service in purifying the waters of the pool, the shore, and even the
sea. Not only in this are they serviceable, but to a great extent
they serve as food for other animals, their flesh being palatable
and preferred to that of other animals whose diet would seem to make
them more wholesome. The small forms exist in such myriads, and
increase so rapidly, that, although extremely small, they furnish an
inexhaustible supply of food. Even some whales subsist upon these
minute animals, and for man the larger species are articles of diet
that are counted among the luxuries. The crustaceans are remarkable
for their varied forms and for their [pg246] perfect adaptation to
many different conditions of life. There is no class in the animal
kingdom which presents so wide a range of organization, or whose
structure deviates so widely from the type form. These differences
lie chiefly in the external characters and in the structure of the
appendages.
Some species are solitary, like lobsters and crabs; others, like
shrimps, are gregarious and live in immense shoals. In the habits of
these animals there is much which excites wonder and interest.
ANATOMY OF THE HIGHER CRUSTACEA
The body of a crustacean is divided into segments, which are
sometimes distinctly separated, like joints, and sometimes fused
into one piece. The head part is called the /cephalic/ portion,
the middle section is the /thorax/, and the posterior part is the
/abdomen/. The horn-like covering of the thorax is the /carapace/;
where it projects over the head it is the /rostrum/. When the head
and thorax are united, as in most /Crustacea/, the anterior or front
portion of the animal is called the /cephalothorax/. Each segment
has a pair of appendages. Each appendage has a joint attached to the
body; from this arise two jointed branches, the /endopodite/ and
the /exopodite/, the inner and the outer foot. The appendages are
modified to perform special functions. In front of the mouth are two
pairs: the smaller ones are the /antennules/ and have ears at the
base; the larger ones are /antennæ/ and are feelers. At the base of
the antennæ are the /green glands/, said to have renal functions.
Both the antennules and the antennæ are fringed with hairs, which aid
in the sense of touch and perhaps of smell. On each side of the mouth
are the /mandibles/. Then come the /maxillæ/ and the /maxillipeds/,
used in capturing and tearing the food and conveying it to the mouth.
Thus it will be seen that some of the appendages around the head
are connected with the senses, and others are used in eating. Those
of the thorax are for walking; those of the abdomen for swimming,
guarding the eggs, etc. The food taken into the mouth passes into
the stomach through a short passage. The stomach is divided into two
parts. The front [pg247] one contains three long teeth which meet
laterally and grind the food; this is known as the /gastric mill/.
When sufficiently fine, the food passes through a strainer of stiff
bristles into the smaller portion of the stomach, where it is
partially digested, and from there enters a long, straight intestine
which reaches the length of the body and opens to the outside on
the under side of the /telson/, or last segment. A large liver also
pours its secretions into the intestine. The green substance commonly
called "fat" in lobsters is the liver.
The heart consists of an elongated tube, or a short sac, which lies
directly under the integument of the back. From this heart-sac,
blood, which is colorless, is sent by arteries to all parts of the
body; it then collects in spaces called /venous sinuses/, from which
it goes to the gills, and thence back to the heart.
The nervous system begins in a large ganglion in front of the mouth,
called the brain; from this two branches arise, which pass on each
side of the digestive organs, meeting in ganglia in each segment
and extending the whole length of the body. The gills, by which the
animal breathes, are upon the limbs, or on the walls of the body
immediately adjacent to them, and are generally inclosed in special
chambers. In lobsters and crabs two such chambers are found under
the flaps of the carapace, above the walking-legs. Gills are divided
so as to present much surface to the water, from which they absorb
oxygen. They are like a dense mass of little tubes arranged along a
central tube. The class has two kinds of eyes, simple and compound;
the latter are composed of a number of eyes. In some species the eyes
are placed on the ends of movable stalks, which enable the creature
to see in all directions and from a higher plane than the body
occupies. As a rule, the eyes occur in the head region, but in the
shrimp /Euphausia/ they are on the thorax and abdomen. In barnacles
simple eyes exist in the young stage, but in adult forms there are
no apparent visual organs. The ear (so called) consists of a sac
containing small silicious particles suspended in fluid. Numerous
fine hairs on the inner surface of the sac connect with nerve-fibrils.
The organs of hearing are in various places. In decapods, or the
larger /Crustacea/, they are at the base of the antennules. [pg248]
The muscles are white bundles of fibers, and are in strips, which is
an indication of power and activity. There are four important sets:
twisted ventral muscles which bend the tail and are particularly
large and strong, those which straighten the tail, those moving the
appendages, and those which work the gastric mill.
[Illustration: Zoëa of /Cancer irroratus/. Last stage before it
changes to the megalops condition.]
The eggs, after being discharged, are attached to the abdominal legs
of the mother by a kind of cement, or they are carried in pouches
attached to the thorax. In these positions they mature, and hatch at
different stages of development in different species. Some emerge
with three pairs of legs, and are known as /Nauplius/; some are
/Zoëa/, having a carapace and abdominal segments, but no abdominal
appendages. Another stage is /Megalops/, with large stalked eyes.
Others are hatched as miniature adults. These names were given when
the embryo stage was not recognized and the larvæ were thought to be
distinct species.
[Illustration: Megalops stage of /Cancer irroratus/, just after
change from zoëa stage.]
The growth of the animal is effected by moulting. The /Crustacea/
are named from the crust-like covering which envelops them. It is
a horny material, called chitin, in which are deposited particles
of carbonate of lime, making a rigid envelop which would prevent
all freedom of motion, were it not that there are spaces free from
lime, and thus flexible joints are left. When the animal expands it
throws off this hard covering and secretes a new and larger one. As
the time of moulting approaches, the old covering becomes loosened,
and a delicate new one is formed beneath it. The old shell splits
open across the back just behind the carapace, and the soft animal
withdraws first its cephalothorax and then its abdomen, leaving the
cover complete, including even the covering of the eyes and the
lining of the stomach. The [pg249] new shell is rapidly hardened,
being already formed when the old one is cast, and the animal
regains its normal condition in about a week; in the meantime it
is defenseless, and lies quiet in some secluded place. Moulting is
an exhausting process, and is attended with great dangers. A great
mortality occurs at this time from accidents, from weakness, and also
from helplessness in case of attack.
The hair-like processes scattered over the shell, often like fringes,
are said to be organs of feeling.
SUBCLASS =ENTOMOSTRACA=
These are /Crustacea/ of small, often microscopic size, of
comparatively simple organization, and with appendages adapted
to serve the purpose of respiration. These minute animals may be
obtained by skimming the surface of the water with a muslin net,
preferably at night, then washing off the inside of the net with a
small quantity of water into a glass dish. Place the dish on a dark
surface before a light, and the little creatures will gather toward
the light, and may be satisfactorily observed with a glass.
ORDER =COPEPODA=
This order, though composed of minute forms, is one of great economic
importance, from the fact that the little crustaceans exist in
vast numbers and furnish a very considerable part of the food of
many fishes. ^Cyclops^ is the most common of the fresh-water, and
^Cetochilus^ of the marine genera. These, together with other genera,
swarm in water wherever life exists, from the smallest pools and
ditches to the broad surface of the ocean. Without having drawn
a surface-net on some sheltered bay, it is difficult to have an
idea of the myriads of /Entomostraca/ in the sea. Although nearly
transparent and of such delicate texture as to be almost jelly-like,
they sometimes color the sea with a reddish tint for miles. Whales
which have baleen, or fringes of whalebone, in the mouth subsist
on these small organisms, which are called "brit" by the whalemen.
The whales, sometimes in schools, rush through the water with open
mouths, engulfing these little [pg250] crustaceans, the baleen
straining them from the water. Although devoured in such immense
quantities, and sometimes lying dead in sheets of scum on the surface
of the water, they maintain their numbers by the exceeding rapidity
with which they reproduce. It has been computed that the descendants
of one /Cyclops/ may number in one year 4,500,000,000, provided all
the young reach maturity and produce a full number of offspring.
One of the free marine forms, ^Sapphirina^, is of especial interest,
as it surpasses all animals in phosphorescence and sparkles by day as
well as by night. It is one quarter of an inch long, and is broad and
flat.
Besides the myriads of free-swimming copepods, there are parasitic
forms in great number. The marine parasitic forms are commonly known
as fish-lice. They have various habits, some living as commensals,
others attaching themselves to animals only to be carried about; the
true parasites live upon the blood and tissues of their hosts, and
may fasten themselves to the external parts of the body or to the
internal organs. Whales, fishes of all kinds, mollusks, starfishes,
jellyfishes, and corals, all have some form of parasite, and many
have several different kinds of guests. It is said that the haddock
has more than a dozen which infest its external and internal
membranes.
^Nicothoë^ is found on the gills of lobsters. The truly parasitic
forms are usually very degenerate and lose the characteristics of
their order.
ORDER =CIRRIPEDIA=
("/Curled feet/")
THE BARNACLES
Barnacles of the genus /Balanus/ (acorn-shells) (Plate LIX.) are
familiar objects on rocky shores, which they often whiten with their
shells, and those of the genus /Lepas/ are also widely known. The
name of the order is descriptive of their curled appendages. The
appendages are fringed like feathers and are drawn into or protruded
from the shell at will. When extended they are constantly in motion,
and create currents which carry food to the [pg251] mouth of the
animal, which is dependent upon such food as comes within range of
its tentacles.
[Illustration: /Balanus./ A, external view: /s/, scutum; /t/, tergum.]
[Illustration: /Balanus./ B, anatomy: /a/, antennules; /ad/, adductor
muscle; /m/, muscles of scuta and terga; /o/, edge of parapet; /ov/,
ovary; /ovi/, oviduct; /sc/, scutum; /sk/, parapet; /t/, tergum;
/wo/, female aperture.]
Their life-history is interesting. The young barnacle, called a
/nauplius/, in no way resembles the adult. When it emerges from the
egg it is a free and independent animal, with one eye, three pairs
of legs, and a single shell. It swims about for a while and moults
several times. It then has two eyes, two shells, and six pairs of
legs. At this period it seeks a permanent home, and attaches its
anterior end to the object it selects by means of its antennæ,
which have become suckers. It makes its hold secure by secreting a
cement which permanently fastens it to the spot. It then undergoes
metamorphosis, loses its bivalve shell and its eyes, and attains its
characteristic /cirripeds/, or curled feathery legs, and a new shell
covering. During these transformations, from the time it becomes
fixed until it attains its adult form, the barnacle fasts, living by
the absorption of its own animal fat. Its food subsequently consists
of the minute animal forms which abound in the sea. Its further
growth is by moulting, but parts only of its covering are disengaged;
the shell is permanent, and its successive stages of growth are
marked upon it by lines, as in mollusks. The lining of the shell, or
enveloping skin of the animal, and also the cuticle of the legs are
[pg252] shed, and in the spring of the year these thin, glossy casts
are found in abundance floating on the surface of the water near the
shore.
There are but three orders of barnacles, namely, those in which the
shell is directly attached to the rocks, those which are attached to
floating objects by a long stalk, and those which are parasitic on
animals. A species of the third order infests the whale.
The older zoölogists classed barnacles with the /Mollusca/, but in
1829 Vaughan Thompson, in the study of their embryology, found that
they should be classed with crustaceans, in company with crabs,
shrimps, and water-fleas, with which their immature forms show direct
relationship.
GENUS ^Lepas^
This genus is commonly known as the ship-barnacle, also as the
goose-barnacle. It attaches itself to floating logs as well as to
ships, but the latter form its principal home; consequently it
is a great voyager, and, though common everywhere, is everywhere
considered a stranger. The same species are found on ships coming
from the most remote and widely separated regions, and so they cannot
be considered native to any one locality. They are wanderers on the
deep, and grow in such numbers on the bottoms of ships, especially
of those which sail in warm seas, that they seriously impede the
progress of the vessels. Aside from diminishing its speed, they do a
ship no injury.
There was a tradition, which lasted several centuries, that geese
were hatched from these shells, which somewhat resemble eggs. Gerard,
in the appendix to his "Herball or Generale Historie of Plants"
(1597), gives a picture of shells of /Lepas/ growing on a tree, with
geese falling from them and swimming about in the water below. His
description is as follows: "There are founde in the North parts of
Scotland and the islands adjacent called Orchades certaine trees
whereon do growe certaine shell fishes of a white color, tending to
russet, wherein are conteined little living creatures; which shells
in time of maturitie do open, and out of them grow those little
living foules whom we call barnakles, in the North of England brant
geise, and in Lancashire tree geise; but [pg253] the other that do
fall upon the land do perish and come to nothing." He then describes
in detail the various transformations, and ends with: "But what our
eies have seen and hands have touched we shall declare."
The long, flexible stalk of /Lepas/ is its anterior end. Generally
this stalk is only half an inch long, but in some species it attains
the length of a foot.
Huxley describes the barnacle as a crustacean fixed by its head and
kicking food into its mouth with its legs. The mouth has a pair of
small mandibles and two pairs of maxillæ, the last pair uniting to
form a lower lip. The thorax has six pairs of branched appendages.
The body is enveloped in a fold of skin, to which are attached five
shell-like plates. One of these plates is long and narrow, and
extends along the dorsal side; two are large and triangular (the
terga); two are small and triangular (the scuta), the long point
extending downward. These shells are on the free or posterior end.
Barnacles have a nervous system, consisting of a brain and a chain
of five or more ganglia, but no special respiratory or circulatory
organs are known; the cirripeds, or feet, are supposed to perform
these functions. They have also a food-canal, a digestive gland, and
excretory tubes. The eggs are carried under the external fold of the
skin in flat cakes.
^L. anatifera.^ The shell is bluish-white, showing lines of growth
and faint radiating lines emanating from the anterior basal angle.
The upper valves are narrow; the long tips point downward, and
the top is blunted, leaving a space which is occupied only by a
membrane. Near the apex of the shell, at the back, is a distinct
angle. The dorsal valve is broad, not much compressed, and is
sometimes grooved lengthwise. The cartilage of the shell and
the stalk adjoining the shell are orange-colored. The stalk is
grayish-brown and the cirri flesh-colored. The stalk is from one
inch to six inches long. The shell is one inch long.
^L. striata.^ Shells bluish-white; valves sharply triangular;
dorsal valve compressed, forming a ridge; lines radiate from the
basal angle of the lower valves and from the upper angle of the
terminal valves, starting from the extreme end; the margins have a
narrow edge of yellow cartilage; the stalk and cirri are of a dark
slate-color; shell and stalk are each about an inch long.
^L. pectinata.^ Shell shorter and less compressed than in the
preceding species; lines of growth and radiating lines distinct; a
decided line [pg254] runs from anterior base to summit, a little
back of the margin; terminal end broadly obtuse (truncated); dorsal
valve much compressed, forming a sharp edge serrated with ten to
twelve teeth and distinctly striated or furrowed.
[Illustration: /Lepas anatifera./ A, the entire animal; B, anatomy.
/a/, antennule; /c/, carina; /cd/, cement-gland; /l/, digestive
gland; /m/, adductor muscle; /od/, oviduct; /ov/, ovary; /p/,
peduncle; /s/, scutum; /t/, tergum and testis; /vd/, vas deferens;
/h/, tentacles.]
[Illustration: PLATE LIX. Different forms of Balanus. (After Darwin.)
Cenobita diogenes.]
GENUS ^Balanus^
/Balanus/ is known as the "acorn-shell," or "sea-acorn," and is found
in vast numbers and of all sizes between tide-marks, incrusting rocks
and the piles of piers. It also may be found attached to floating
objects or to shells, or even to living animals, but its usual
habitat is stationary. Unlike /Lepas/, it has no stalk, the shell
being directly attached to some object. The body is surrounded by a
fold of skin, to which are attached a shell consisting of six or more
plates and a fourfold lid, or /operculum/, consisting of two /scuta/
and two /terga/. The operculum may be called the door, as the animal
opens and shuts it at will and has complete protection when it is
closed. If one taps a rock [pg255] incrusted with barnacles, and
holds the ear near, the closing of the many doors may be distinctly
heard.
The development of /Balanus/ from the larval stage, as also the
anatomy of the adult, is similar to that of /Lepas/. When covered
with water and unmolested, there may be seen over a bed of barnacles
thousands of tiny fringed feet waving to and fro. The motions look
like gestures; they are perfectly regular and rapid, numbering
eighty to a hundred a minute. The shell covering formed by barnacles
on piles of wharves and bridges is said to be a protective agent;
otherwise the barnacles seem to have no economic value in nature,
as, unlike other animals, they do not serve, except in very small
measure, as food to other classes. The tautog and perhaps some other
fishes feed partly upon them. They are sometimes an obstacle to
oyster-culture, as they fasten upon the objects intended for oyster
embryos, and, growing faster than the latter, soon crowd them off.
One species, /Coronula diadema/, fastens to the skin of whales. It
attains the size of two inches in diameter. The shell is half an
inch thick and full of cavities, into which the skin of the whale is
drawn, giving the barnacle a secure hold. (Plate LIX.)
^B. balanoides^ (Stimp.), ^B. ovularis^ (Gould), the rock-barnacle.
This is perhaps the most conspicuous of the barnacles. It inhabits
the whole northern Atlantic coast, and is so abundant that it not
only whitens the rocks with a complete incrustation of shells, but
the animals are so crowded that many of them lose their normal
shapes and become greatly elongated. When the rocks are covered
with water they seem alive, on account of the thousands of waving
tentacles. This species also incrusts woodwork between tide-marks.
The shell is small, white, and variable in shape; sometimes its
height is less than the diameter of its base; again the height is
several times greater and the summit broader than the base. In its
early stages the valves are smooth, but later the base is scalloped
by four or five grooves. The summit of the plates is even and
blunt. The aperture is diamond-shaped. Two valves of the operculum
are pointed at the tips; two are blunt, making a deep notch in
the summit. These valves are the distinctive feature by which to
recognize this species, which varies so much in outward form; the
species is also distinguished by its membranous base, which does
not form a solid plate like that of other species.
^B. eburneus^, the ivory barnacle. This species, like /B.
balanoides/, is a very common barnacle, and is found on all kinds
of submerged woodwork, whether fixed or floating. It is also found
on the carapace of [pg256] crabs and /Limulus/, and on mollusks.
It is chiefly found on objects below low-water mark. It ranges
from Massachusetts Bay to Florida. It is easily distinguished from
the preceding by its low, broad form and shelly base. The shell is
smooth and circular at the base, and inclines backward, forming an
oblique cone with a triangular opening; the plates terminate in
points at the summit and incline backward, the last one forming a
kind of beak. The operculum is pyramidal; two of its valves have
both transverse and longitudinal lines well defined at the base,
and are coarsely toothed at the edges; the posterior valves are
slightly grooved across.
^B. rugosus^ (Gould), ^B. crenatus^. Shell white, cylindrical,
somewhat conical, rugged, the summit usually as broad as the base;
height often greater than diameter; aperture diamond-shaped, plates
ending at the summit in acute spreading points, the posterior plate
folded and curved like a beak; plates rough, with coarse, irregular
ribs; valves of the operculum at the summit acute, with diverging
points; the points striated. Found on shells and stones in deep
water and also on bottoms of ships.
^B. geniculatus.^ Shell dirty greenish-white, cone-shaped; aperture
about the size of base; shell-plates triangular, unequal in
breadth, and with alternate large and small ribs; the smaller ribs
compressed and roughened on the edges by the conspicuous lines of
growth which run across them; depressed areas between the plates
marked with fine cross-lines; front valves of the operculum have
coarse plated ridges, which incline over one another and are
crossed by fine radiating lines; diameter at base one to one and
a half inches; height two thirds the diameter. Found on pecten
shells, and abundant off the coast of Maine.
^B. tintinnabulum.^ Shell pink to purplish, conical, with six
triangular plates, which are grooved, forming unequal ribs, and
crossed by distinct lines of growth; spaces between plates crossed
by lateral lines; posterior valves of the operculum longer than the
others and curved forward, resembling the beak of a bird of prey;
diameter at the base one inch; height one and a half inches. Found
in warm waters and on vessels from the South.
SUBORDER ~RHIZOCEPHALA~
These are parasitic forms and very degenerate. ^Sacculina^ lives on
crabs, and its term of life is about three years, during which period
the afflicted crab does not moult. Its shape is that of an ovoid sac
on a stalk, which it attaches between two segments of the ventral
surface of its host. The stalk divides and ramifies in a root-like
manner within the body of the crab, from whose vital elements it
absorbs its nourishment. The roots spread like a mycelium through the
whole crab, even to the claws.
^Peltogaster^ lives on hermit-crabs. [pg257]
SUBCLASS =MALACOSTRACA=
This subclass comprises highly organized /Crustacea/, usually of
considerable size, having the appendages much differentiated, the
thorax with eight segments, and the abdomen with seven segments.
ORDER =SCHIZOPODA=
The name, meaning "cleft-footed," applies to the appendages of the
thorax, which are once-branched (/biramous/). Gills, when present,
are attached to these feet, and hang freely in the water. A delicate
carapace covers the thorax; the abdomen is proportionately very
large, often twice the length of the cephalothorax. In /Mysis/ the
eggs are carried in pouches under the thorax, giving the common
name of "opossum-shrimp" to this small, transparent, phosphorescent
crustacean.
[Illustration: /Mysis sternolepis./]
GENUS ^Mysis^
^M. sternolepis.^ About one inch in length; translucent; antennæ
very long; segments marked at joints with dark spots; the last two
segments terminate in a stout spine; telson longer than the sixth
segment; the sides are nearly straight and are armed with spines;
the extremity is cleft; eyes large and prominent. Found abundantly
in winter on the shores of still, muddy bays and sounds, especially
among eel-grass.
ORDER =DECAPODA=
("/Ten-footed/")
The /Decapoda/ are named from their ten walking-legs. The higher
forms of crustaceans belong to this order. All the /Decapoda/
have a similar anatomy, but are placed in two subdivisions
[pg258] according to their external form. In /Macrura/, the first
subdivision, belong the lobsters, crawfish, shrimps, prawns, and
hermit-crabs, animals having a long and more or less cylindrical
body, with the abdomen extended; in /Brachyura/, the second
subdivision, are placed the crabs, animals having the thorax broad
and flat, and the abdomen bent under the thorax. The /Decapoda/
have twenty segments, all of which, except the last one, have, at
some period of life, a pair of appendages. The first two pairs of
appendages, or, in the stalk-eyed forms, the first three pairs,
are especially connected with the senses, and are often fringed
with hairs, which are also considered to have a sense-function. The
/antennules/, or first pair of appendages after the eye-stalks, are
sometimes divided into two or three branches. At the base of the
antennules are the ears. The /antennæ/, or second pair of appendages,
are undivided, but are larger than the first pair, and are often
very long. At the base of the antennæ are the renal glands. Both
the antennules and the antennæ are slender, elongated, movable, and
full of joints. In some species they are greatly modified, as in
/Scyllarus/, where they are developed into broad swimming-plates and,
perhaps, as shovels for burrowing; in some amphipods they are used as
swimming-organs. (Plate LX.)
[Illustration: PLATE LX. External Anatomy of a Lobster. /C/,
carapace; /e/, eye; /g/, gill; /m/, metastoma; /n/, endopodite; /p/,
epipodite; /x/, exopodite; I-VII, abdominal segments; 1, antennula;
2, antenna; 3, mandibles; 4, 5, maxillæ; 6, 7, 8, maxillipeds; 9, big
pincer; 10-13, walking-feet.]
The next six pairs of appendages are grouped about the mouth. They
are the /mandibles/, the /maxillæ/, and the /maxillipeds/. The
mandibles are at the mouth-opening, and, being heavy and hard, are
adapted to tearing and grinding; they have a jointed attachment,
the /palpus/, whose office is to keep the mandibles clean. The two
pairs of maxillæ are delicate and leaf-like. The three pairs of
maxillipeds grow gradually larger, the last pair being very prominent
and extending over the other mouth-parts. Next come five pairs of
walking-feet. One or more pairs of these feet have pincer-like ends,
or claws. Some species have the claws immensely developed, as in
lobsters. The claws are the /chelæ/, and the feet which bear the
/chelæ/ are termed the /chelipeds/. The rest of the walking-feet
have generally single, hook-like ends, but are variously modified
in different species. The abdominal segments have six pairs of
appendages, also variously modified. The last segment is without
appendages, but often is extended into a tail, [pg259] or
fin-like expansion. The next to the last segment, in many forms, has
appendages modified into swimming-plates, which extend on each side
of the telson, forming a broad, fan-like caudal extremity.
They have, then, to correspond to the twenty segments of the body,
two pairs of sensory, six pairs of mouth-, and five pairs of
walking-appendages attached to the cephalothorax, and six pairs on
the abdomen. The terminal segment, or telson, is without appendages.
The exopodite is present on the maxillipeds, but disappears from the
walking-feet in the higher forms.
In moulting the /Macrura/ split in the longitudinal line down the
back; in the /Brachyura/ the split occurs across the body at the
point between the thorax and the abdomen.
SUBORDER ~MACRURA~
SHRIMPS, PRAWNS, LOBSTERS, CRAWFISH, AND HERMIT-CRABS
The characteristic features of the /Macrura/ are an elongated body
with the abdomen usually extended; a carapace, somewhat cylindrical;
and the last pair of appendages of the abdomen (which are attached to
the next to last segment) united with the last segment, or telson, to
form a powerful caudal fin, used for swimming backward. The creeping
forms in moving walk forward, but swim backward.
FREE-SWIMMING FORMS: SHRIMPS AND PRAWNS
In these animals the body is compressed and the carapace is not hard.
The abdomen is very large in proportion to the cephalothorax, and has
a peculiar bend. The rostrum is often longer than the thorax. The
eye-stalks, antennæ, and legs sometimes attain extraordinary length,
and the chelæ (claws) are not always on the first pair of legs. In
some species chelæ are on two or three pairs of the legs. Above the
antennæ are expanded antennal scales, which, together with the long
bases of the antennules and very prominent eye-stalks, make the head
a broad and conspicuous feature. The difference between shrimps and
prawns is not very well defined, the small individuals seeming to
be generally called shrimps, the larger full-grown ones prawns.
[pg260] Prawns are known as /crevettes/ in France and as /Garnelen/
in Germany, where they are largely used as food. In the United States
the shrimp-fishery is an industry of the South. On the California
coast the fisheries are very extensive and are monopolized by the
Chinese.
GENUS ^Penæus^
^P. setiferus.^ This species is about six inches in length when
full-grown. A ridge or crest extends along the center of the
carapace, and terminates in a long, pointed, toothed rostrum,
the teeth being fringed with hair on the inner side. The antennæ
are a foot or more in length; there are chelæ on the first three
pairs of thoracic feet; the swimming-feet and lateral margins of
the segments of the abdomen are fringed with hair; and the caudal
appendages are longer than the telson. It ranges from Virginia
southward, and is very abundant on the shores of the Southern
States, where it is gathered for the markets. The large ones are
known as prawns and the small ones as shrimps.
^P. brasiliensis.^ This species is associated with /P. setiferus/,
and, although not so abundant, forms a part of the shrimp-supply
in the fisheries. It differs from the former in having a groove
on each side of the ridge which runs through the center and whole
length of the carapace. The first three pairs of feet are chelated.
This shrimp is found as far north as Long Island, and often in
brackish water, or even where the water is quite fresh.
GENUS =Palæmonetes=
^P. vulgaris (Palæmon vulgaris).^ Average size one half of an inch
in length; body translucent, almost colorless, irregularly spotted;
rostrum as long as carapace and toothed on the upper edge. It is
found among eel-grass in brackish water, and also in pools and
ditches on muddy shores from Massachusetts Bay to Florida. Commonly
known as prawns.
[Illustration: /Palæmonetes vulgaris/; male.]
GENUS ^Crangon^
^C. vulgaris^, the common sand-shrimp. It ranges from Labrador to
North Carolina on the Atlantic coast and from Alaska to southern
California on the Pacific coast. It is found in abundance on sandy
shores at low-water mark, and in shallow water below tide-mark;
also among rocks and seaweeds. When left by the tide it buries
itself in the sand. Its color varies with its location, rendering
it inconspicuous. Upon the [pg261] sandy shores it is translucent,
pale in color, and often specked, closely resembling the sand,
while on dark, muddy bottoms it is much darker. This is an edible
shrimp, eagerly devoured by fishes; it is also gathered for the
markets. The body of /C. vulgaris/ is broad at the anterior end
and tapers to a sharp point at the posterior extremity. A pair of
broad, divided appendages on the cylindrical segment, which is next
to the last on the abdomen, together with the sharp telson, form a
fan-like swimming-tail. As in all shrimps, the antennæ are long and
have plate-like antennal scales at the base, which are fringed with
hairs. The mandibles are long. The movable finger of the chela is
folded across the extremity of the claw.
^C. franciscorum^, the California shrimp. This species is about
three inches in length. It is distinguished from /C. vulgaris/ by
its larger size and by the greater length of the movable finger of
the chela, which folds parallel to the side of the claw instead of
across its extremity. Its color is light or dark yellowish-gray,
mottled. This is the shrimp extensively gathered by the Chinese for
commercial purposes. The shrimp-meat is dried and cured, and then
separated by blowers very much as wheat is cleaned. It is exported
to Eastern countries in great quantities, the value of the export
being estimated at one hundred thousand dollars per annum.
[Illustration: /Crangon vulgaris/, the common sand-shrimp; male,
natural size.]
CREEPING FORMS: LOBSTERS AND CRAWFISH
FAMILY ~ASTACOIDÆ~
GENUS ^Homarus^
There are but three species of this genus, which is the most
important one of all the /Crustacea/. They are /H. vulgaris/ of
Europe, /H. capensis/ of the Cape of Good Hope, and /H. americanus/,
which occurs on the eastern coast of the United States from Labrador
to New Jersey. The lobster-fishery is one of great importance, and of
such value that it is governed by stringent laws. The [pg262] annual
catch on the Atlantic coast of North America amounts to many millions
of lobsters, the money value of which is very large.
^H. americanus^, the common lobster of the Atlantic coast.
The characteristic feature of the lobster is its enormously
developed chelæ, or pincer-claws, which are on the first pair of
walking-feet. Small claws occur on the next two pairs, and simple
hooks on the remaining two pairs. The appendages on the abdomen are
divided (biramous). In the female they are used, excepting the last
pair, for holding the eggs; in the male they are greatly abridged.
The appendages on the next to last segment are divided and broadly
flattened, forming with the telson a powerful swimming-paddle. The
rostrum is very prominent, and has a long, pointed end, slightly
upturned, and several spines.
The lobster belongs to the creeping forms of the order; it walks
forward by means of the ten feet, but swims backward by using its
caudal fin. It lives in deep water on rocky bottoms, hiding among
stones, etc., but frequents sandy shores as well. It lives on
dead and decaying animal matter, and it would seem strange that
its flesh is so palatable, were it not that we know that chemical
combinations which take place in the assimilation of food make one
kind as clean, when transformed, as another. All the crustaceans
have a similar dietary, being scavengers of the sea; yet fishes
find them more acceptable than other animal food, and fishes
capable of capturing larger prey subsist largely on the minute
entomostracans described elsewhere.
[Illustration: /Homarus americanus/, American lobster; male.]
The lobster is so large that it can easily be dissected, and will
serve as a type of the structure of /Crustacea/. In dissecting one
can follow the descriptions given of the anatomy of /Crustacea/
on page 246, and will be interested in observing the beautiful
arrangement of the parts and their adaptation to the uses they
serve. [pg263]
The female lobster carries her eggs on the abdominal legs, to which
they are glued by a kind of cement. After the young emerge from
the egg, the zoëæ still cling to the mother for a little time.
The lobster moults eight times the first year, five times the
second, and three times the third year, after which the male moults
twice and the female once a year. It retires to some secluded
spot for this operation, which is attended with many dangers. The
back splits open longitudinally and the animal slowly withdraws,
leaving the shell complete. In preparation for moulting, the lime
around the contracted joints of the chelæ is absorbed, so that the
soft flesh can pass through. Any injury to a limb at the time of
moulting, or which results from fighting or from any accident, is
repaired at successive moultings, and a lost member is replaced by
a new, but not always a perfect, one.
GENUS ^Panulirus^
^P. interruptus.^ This is the California spiny lobster,
rock-lobster, or salt-water crawfish. It differs from the common
lobster /Homarus/ of the Atlantic coast in having no large claws,
the first pair of feet being simple like the rest, also in having
antennæ which are enormously long and very large at the base. The
carapace is beset with spines, and the lateral margins of the
abdominal segments end in spines. This species lives among the
rocks on the southern California coast.
[Illustration: /Panulirus interruptus/, the spiny or rock-lobster.]
^P. argus^ or ^americanus^ resembles /P. interruptus/, and is found
on the coast of Florida.
GENUS ^Scyllarus^
/Scyllarus/ has a broad, almost square carapace, which is uneven and
coarsely granulated; the anterior corners are sharp, the posterior
ones rounded. The antennæ are curiously modified into broad, flat,
double plates reaching quite across the straight anterior end of the
carapace. The under scales of these modified antennæ are rounded and
leaf-like, the upper ones are pointed. The margins of the abdominal
plates on the ventral side are toothed, and on the upper side the
first three sections have [pg264] knobs, the third one being the
most prominent, and forming the posterior extremity when the abdomen
is folded in. The walking-feet are all simple and end in points;
the first pair are the longest, and the following ones gradually
diminish in size. The ventral surface is rough and spiny. The abdomen
is of about the same length as the carapace. These animals are found
off the Florida coast and are caught in the fish-traps. They are
uncommon. The very peculiar development of the antennæ makes them
worthy of examination when opportunity offers.
ANOMALOUS FORMS: ANOMURA
The anomalous forms which are intermediate between the suborders
/Macrura/ and /Brachyura/ were, until recently, placed in a suborder,
/Anomura/. The members of this group differ from one another, and
some of them resemble in external features members of the other
divisions of the suborders, but there is a difference in anatomical
structure which separates them in the classification.
FAMILY ~DROMIDÆ~
GENUS ^Hippoconcha^
^H. arcuata.^ This curious little crab, found on the Florida coast,
carries the half of a bivalve shell over its back. Its fifth pair
of thoracic legs are bent over the back, and these, together with
the fourth pair of legs and the spiny front edge of the carapace,
enable the crab to hold the shell in position. This crab was
formerly classed with the hermits, all of which were originally
called /Bernhardus/, after the monk of that name.
FAMILY ~PAGURIDÆ~
THE HERMIT-CRABS
In these curious animals the posterior part of the body is not
protected by a crustaceous covering, and therefore the animal seeks
protection by inserting its soft and defenseless abdomen into some
hollow object, usually the shell of a gasteropod mollusk, as the
whelk or the periwinkle (/Buccinum/, /Littorina/). The hermit-crabs
do not always use a shell for this purpose, as they are sometimes
found in the tubes of plant-stems or in sponges. Like other
organisms in the animal world, they seem [pg265] well fitted to
make the best of their surroundings, the body becoming modified to
suit the peculiar conditions under which they live. In those which
inhabit shells the abdomen becomes spiral, in conformity to the
convolutions of the shell. All the abdominal appendages are more or
less atrophied; the sixth pair become like hooks, and these fasten
to the columella of the shell, keeping the crab securely attached
to it. In the female some of the abdominal appendages are hair-like
and are adapted to carrying the eggs. The thorax, being protected,
is protruded from the shell at will. The first pair of feet are much
larger than the others, and are provided with claws (chelæ). The
first right foot is usually much larger than the left, and, besides
the usual functions of capturing and crushing prey, the claw, or
hand, serves as an operculum to close the mouth of the shell when the
crab retires completely within it. The small left hand is shaped to
fill out the parts of the opening not covered by the right one, thus
making a close fit. The next two pairs of feet end in simple hooks,
and are used for walking and dragging the crab along when he travels.
These crabs move about very fast, and the houses upon their backs
seem no encumbrance. [pg266]
[Illustration: /Pagurus bernhardus/: /ch/, chela of first right leg;
/l./4, /l./5, fourth and fifth legs; /t/, abdominal terga; /up/, last
pair of appendages, modified to fasten to the columella of the shell
in which the hermit lives.]
In some genera both hands are alike; in others the left one is the
larger. In the case of hermits which live in tooth-shells, the
right hand is cylindrical in form, fitting the circular opening of
the shell. The other extreme is found in the genus /Cancellus/,
where both the chelipeds and the first pair of ambulatory feet are
ingeniously shaped, so that when closed they form a round operculum,
or door, which closes the way into the compact sponge which this crab
has for its carcinœcium, or house. It is interesting to note these
differences and observe the perfection with which the feet are formed
and jointed to suit the openings of different shells. Some genera
show other adaptations to their twisted houses, the eye-stalks being
uneven in length and the ambulatory feet unequal on the opposite
sides. Besides this, some species are hairy and cover themselves with
dirt for further protection. The exposed claws of some hermits have a
special armature of spines, which make a fringe of points around the
opening of the shell when the crab is withdrawn.
As the hermit grows he is occasionally obliged to find a new or
larger shell, and there are amusing anecdotes of the troubles he
experiences at these times while house-hunting. Very often he tries
several shells before he finds one to fit. There is a tradition,
not, however, well authenticated, that if the shell chosen happens
to be occupied by its natural owner, the crab tears out and devours
the unfortunate occupant. If the desired shell is occupied by
another hermit inferior in strength to himself, he proceeds to take
possession by violence. He then examines carefully the empty shell,
inserting his legs and feelers, and if he decides to occupy it he
withdraws his abdomen from the old shell and darts it so quickly into
the new one that the act of transference is difficult to follow.
After walking about with the new shell it sometimes proves to be
unsatisfactory and further search becomes necessary. After it is
well domiciled the crab never ventures outside the shell until it
is obliged to change again on account of growth, or because some
stronger crab dispossesses him. The shells of hermit-crabs serve
frequently as the home of other animals which live with them a
commensal life. The hydroid /Hydractinia polyclina/ often covers
the exterior of such shells with a brown, velvety growth. Some
sea-anemones also are commensals [pg267] with hermits. /Adamsia
palliata/ is always found on the shell occupied by /Eupagurus
prideaux/, and never on any other. This is a European form. On
our own coast a red anemone, the /Epizoanthus americanus/, found
in deep water off the entire eastern shore, fastens on the shell
occupied by the hermits /Eupagurus pubescens/ and /E. kroyeri/. This
anemone in time absorbs the shell of its host and itself becomes its
protector—an advantage to the hermit, who finds room in the yielding
polyp-mass for its increasing size, and feels no longer the necessity
for change of domicile. The female hermit holds its eggs in the
posterior feet until they are hatched; the young are then released,
pass into the water, and soon find shells for themselves.
[Illustration: A colony of sea-anemones (/Epizoanthus americanus/)
which had completely covered and absorbed a shell occupied by a
hermit-crab (/Eupagurus pubescens/), which still lived within the
cavity. The polyps are not expanded.]
GENUS ^Pagurus^
^P. bernhardus.^ This is a large species, bright red in color,
rough and hairy. It inhabits the shells of /Fulgur carica/ or
of /Polynices heros/. It ranges from Cape Cod northward, and is
replaced on the northern California coast by /P. alaskensis/ and
/P. aleuticus/.
[Illustration: /Pagurus bernhardus/, the hermit-crab.]
^P. pollicaris.^ This hermit inhabits shells similar to those
occupied by the last, but is pale red in color, and its surface
is granulated and not hairy. The short joint of the chela has a
broad angle. It ranges from Massachusetts to Florida, and occurs at
low-water mark on rocky and shelly bottoms of bays and sounds.
^P. longicarpus.^ A quick-moving little hermit with long chelipeds,
found in small shells at the water's edge in quiet places. They
exist in great numbers and are eaten, shell and all, by fish. This
species can be distinguished from all others by its very light
color and metallic luster.
GENUS ^Clibanarius^
^C. vittatus.^ This hermit is found from North Carolina southward
along the edge of the water and in tide-pools. It cannot be
mistaken [pg268] for any other hermit common on our coast, since
it has the very distinctive feature of white longitudinal stripes
on the ambulatory feet. The chelipeds are about equal, rough with
tubercles, and the tips have smooth black edges. Body and feet are
quite hairy. The color is brown and white.
GENUS ^Pylopagurus^
This genus is represented in Southern waters by several species.
One of the most characteristic of them lives in /Dentalium/, the
tooth-shell. The outer surface of the right hand is formed to close
the shell. All the ambulatory feet and the very small left hand fold
beneath, leaving only the flat surface of one hand exposed to view.
Another species lives in a shell covered with polyzoans.
FAMILY ~CENOBITIDÆ~
GENUS ^Cenobita^
^C. diogenes.^ This large hermit-crab, found in Florida and in more
southern waters, inhabits the beautiful pearly shell of /Livona
pica/. It lives on land a part of the year, but spends the breeding
season in the water. It can be distinguished by its land-roaming
habits, its large left cheliped, very stout walking-legs, and
compressed eye-stalks. This species climbs the hills, but is more
frequently met with in low, shaded, marshy places. (Plate LIX.)
FAMILY ~HIPPIDÆ~
GENUS ^Hippa^
[Illustration: /Hippa talpoida/, the sand-bug.]
^H. talpoida.^ This animal, commonly known as the "sand-bug,"
differs greatly in appearance from a crab. When the appendages are
folded under the carapace it somewhat resembles an egg, the body
being ovate, about half as broad as long, and the sides forming a
nearly regular curve. The carapace is about one and a half inches
long, convex, yellowish-white, and nearly smooth. The abdomen is
long and pressed under the body, reaching nearly to the front.
The eyes are minute and on the ends of long, slender stalks. The
antennæ are plume-like and about as long as the carapace. /Hippa/
lives on sandy beaches at or near low-water mark, exposed to the
action of the waves. It burrows with great rapidity into the loose
and shifting sands, using the short and stout second, third, and
fourth thoracic legs and the appendages of the sixth abdominal
segment [pg269] for pushing and digging. Crabs of this species
are gregarious and may be seen in great numbers, though but few
will be captured together by digging, as they rapidly disappear
beneath the sand. Sometimes they are found swimming about in the
tide-pools. They seem to live upon the organic particles contained
in the sand, which they swallow, the mouth not being adapted for
mastication. This species ranges from Cape Cod to Florida. (Plate
LXI.)
^H. analoga.^ Similar to /H. talpoida/, but broader and flatter. It
is bluish above, yellowish-white below, and the fringing hairs are
black. Found on the California coast.
GENUS ^Albunæa^
^A. gibbesii.^ This animal is found with /Hippa/, and, like it,
burrows rapidly in the sand. Its general outline is square. The
surface of the carapace is marked off with denticulated lines,
which make the back appear as if composed of plates. The front edge
of the carapace has a row of teeth and a prominent spine at the
anterior angles. The abdomen is doubled under itself (not fitting
into a groove of the thorax, as in ordinary crabs), this animal
being intermediate between the long- and the short-tailed forms.
The eyes are on triangular, plate-like stalks. The antennules are
very long and are fringed with hair. The chelipeds have claw-like
joints, which close across the straight, broad end of the hand.
The first two pairs of walking-feet have curious sickle-like
terminal joints. The animal is about one and a quarter inches long.
/Albunæa/ does not extend as far north as /Hippa/, its range being
from Georgia southward. (Plate LXI.)
FAMILY ~PORCELLANIDÆ~
The crabs of this family are little more than one quarter to one half
of an inch across the back. The chelipeds are broad and flattened.
The first three pairs of walking-legs are well developed, and the
fifth pair are very small and are doubled over the base of the
carapace. The sixth segment of the abdomen has a pair of biramous
appendages, which, with the telson, form a swimming-fan.
GENUS ^Porcellana^
^P. sayana.^ Carapace little longer than broad; breadth about one
quarter of an inch; smooth; has three acute denticulations between
the eyes, the middle one the largest and depressed in the center;
two denticulations on each anterior side; chelæ fringed with hair
on the edges; walking-legs somewhat hairy; fifth pair of legs
folded over base of carapace; color reddish, with white spots.
This species was once called /occulata/, because of the eye-like
spots over its entire surface. The posterior part and abdomen have
longitudinal bands of color. The claws are marked like the shell.
Found from South Carolina southward, often in the shells inhabited
by hermit-crabs. (Plate LXI.) [pg270]
GENUS ^Petrolisthes^
^P. sexspinosus.^ Carapace longer than broad; breadth about one
half of an inch; space between the eyes broad, but not divided into
three teeth as in /Porcellana sayana/; second joint of the cheliped
has five broad teeth on its front edge and five or six small
spines on its outer edge; fifth pair of legs doubled over base of
carapace; whole body traversed with broken red lines. Found from
South Carolina southward. (Plate LXI.)
^P. armatus.^ Carapace longer than broad; breadth about one
quarter of an inch; prominent and wide between the eyes; a small
sharp spine on each anterior side; chelipeds long; second joint
of cheliped twice as long as broad, with three teeth on the front
edge and four or five small spines on the outer edge. Found on the
Florida coast. (Plate LXI.)
FAMILY ~LITHODIDÆ~
The species of this family have a broad, ovate, uneven body and
a prominent rostrum. The fifth pair of legs are rudimentary and
are folded under the carapace in the branchial chambers, so that
the crabs appear to have but four legs on each side. This is
the distinguishing feature of the family, and makes them easily
recognized.
GENUS ^Lithodes^
^L. maia.^ The carapace is cordate (heart-shaped), and longer than
broad, exclusive of the rostrum. The margin is recurved all around,
and is beset with numerous very long spines. Six spines on each
anterior side margin are regular and longer than the others. The
surface of the carapace is covered with tubercles and spines and
elevated in places. The rostrum is spiny, a third as long as the
carapace, and has two spines at the base, one above the other,
a spine at each side, two lateral spines near the middle, and
two terminal divergent spines. The chelipeds are unequal and are
covered with spines, those on the inner margin being the longer.
The color is yellowish-red, lighter underneath; the spines are
darker. Found on the fishing-banks off the coast of Maine. (Plate
LXI.)
[Illustration: PLATE LXI. 1, Hippa talpoida. 2, Albunæa gibbesii.
3. 1, Porcellana sayana; 2, Petrolisthes armatus; 3, Petrolisthes
sexspinosus. 4, Lithodes maia.]
[Illustration: Plate LXII. Echidnocerus cibarius. Cryptolithodes
sitchensis. Echidnocerus foriminatus. Phyllolithodes papillosus.]
GENUS ^Echidnocerus^
^E. cibarius.^ This curious crab has the carapace raised in front
into a large cone-like elevation terminating in a long point. Three
prominent but smaller cones extend across the center of the back,
and two still smaller ones occur on the posterior sides and in the
middle of the posterior margin. The whole surface of the carapace
is covered with coarse granulations arranged in rosette-like
groups. The chelipeds and legs are beset with large tubercles and
fold together in such a manner that when retracted the crab is a
close, compact, box-like mass, with a very rough, [pg271] spiny
armature. The antennæ are broad at the base and covered with small
spines on the sides and upper surface, and the eye-stalks are also
spiny. This crab sometimes attains the size of ten inches across
the carapace and a weight of seven pounds, being among the largest
crabs known. It is found at the mouth of the Columbia River and
along the northwest coast. (Plate LXII.)
^E. foriminatus.^ This species resembles /E. cibarius/ in the
manner of closing the feet, forming a compact, box-like, spiny
armature. The body is more depressed than that of the latter,
and the cone-like elevations on the back are less prominent. The
spines are hairy. The characteristic feature of this species is a
semicircular cut in the second joints of the chelipeds, directly
opposite to similar depressions in the first walking-legs, so that
when the feet are folded a round hole is left, through which water
flows freely to the gill-openings, which might, without these open
holes, be obstructed by the close folding of the legs against the
carapace. Found off the California coast near San Francisco. (Plate
LXII.)
GENUS ^Acantholithodes^
^A. hispidus.^ The whole body in this species, including the legs,
is covered with hairy spines. The abdomen is broad, and covers
about the whole under surface of the body, and is also beset with
hairy spines, but they are less prominent than those on the upper
side. The rostrum, terminating in spines, reaches to the tips of
the eye-stalks, which are also spiny. The chelipeds are larger and
longer than the walking-feet; the latter taper to a point, ending
in a sharp nail. The shape of the body resembles somewhat that of
a toad. This is a deep-water species, but it is sometimes brought
ashore at Monterey, California, by fishermen who find it in the
stomachs of fishes.
GENUS ^Cryptolithodes^
^C. sitchensis.^ The most striking characteristic of this singular
species is the great development of the carapace, which forms
a broad, thin shield extending beyond the body and legs, and
completely hiding the animal beneath it. The carapace is smooth
and uneven, has a high ridge through the center of the anterior
part, and the sides are broadly expanded and bluntly pointed at the
extremity. The rostrum appears like a small rectangular piece cut
out of the anterior side of the carapace. This species is found in
the Strait of Fuca. A similar species, /C. typicus/, is found near
low-water mark on the surf-washed rocks of the beach at Monterey,
California. (Plate LXII.)
GENUS ^Phyllolithodes^
^P. papillosus.^ The carapace is triangular, about two inches
wide at the base, and narrowing to a long, pointed rostrum which
terminates in a forked spine. The surface of the carapace is deeply
depressed in parts, and forms a heart-shaped figure in the center.
The lateral margins have four prominent spines on each side, the
two at the posterior ends being [pg272] thicker than the other
two. The abdomen is broad, covering the whole under side of the
body, and is marked off with prominent raised ridges diverging from
the center line. The legs are all beset with long, rough spines.
Habitat, the northwest coast. Taken from the stomachs of fishes off
Monterey, California. (Plate LXII.)
SUBORDER ~BRACHYURA~
THE CRABS
This group contains the true crabs, which are the highest of the
/Crustacea/. In form they are quite the reverse of the first group.
In the /Macrura/—except in the anomalous forms—the body is long
and cylindrical and the abdomen extended, but in the /Brachyura/ the
body is flat and broad and the abdomen short and reflexed. Crabs of
this suborder inhabit all seas of the globe, and are found from the
shore to great depths. Some species live on land, some on the shore,
some in deep water. Some forms burrow in the sand; others live under
stones and boulders, or conceal themselves in crevices of rocks or
in the cavities of sponges. They are divided into many families,
and creep, climb, swim, or burrow, their structure being modified
to their respective modes of life. There is also great variation in
their shapes as well as in their color and markings. This diversity
is so great and peculiar that it seems as though each one were more
curious than the others.
In crabs the cephalothorax is depressed and often broader than long.
The abdomen is relatively small and is folded under the thorax, lying
in a groove which it fits so perfectly as to be quite hidden from
above. The appendages of the abdomen are much reduced in number. The
male has two pairs; the female has four pairs, which it uses for
carrying its eggs. The first pair of walking-legs are comparatively
large, and end in chelæ, or pinching-claws. The other eight legs
terminate in simple points, except in the swimming varieties, when
the fifth pair is flattened to form fins, or swimming-paddles. The
eye-stalks are long and fit into sockets on the carapace. Both pairs
of feelers are small. The antennules are frequently folded into small
grooves. The external or third pair of maxillipeds are broad and
flat, and cover the mouth-parts like a lid, or operculum. [pg273]
Crabs, like other crustaceans, are scavengers, living on dead animal
matter; but the land species are also vegetarian in diet. They are
great fighters, but are also wily, often averting danger by resorting
to stratagem. They are an interesting and curious group, as they
possess a good degree of intelligence and have amusing habits.
From the time they leave the egg until they attain the adult form
they pass through several complete and singular metamorphoses. The
most marked forms are called the /Zoëa/ and the /Megalops/. So little
do these resemble the adult that originally they were classed as
distinct genera far removed from the one to which they really belong.
After the larva has moulted several times it appears as in the
illustration on page 248—the last zoëa stage. From this it changes
directly to /Megalops/; the /Zoëa/, seeming to be attacked with
violent convulsions, wriggles out of its skin a full /Megalops/ (page
248). The animal then has enormous eyes, an extended abdomen, an
elongated carapace, and swimming-legs. This stage is a short one, and
at the first moulting changes to a form nearly approaching the adult.
From this time they grow by shedding the shell at certain periods.
This shedding is supposed to occur twice each summer until they have
reached full growth, after which it is probable that they do not
again moult; for often they are found with extraneous organisms,
such as barnacles and sponges, upon them, of a size that must have
required a considerable period of time for growth. The sexes of
the same species sometimes differ so much that it is difficult to
classify them. Even naturalists have been led into the error of
assigning the male and female to separate species.
The front side margins of the carapace in many crabs are edged with
a row of teeth or with spines, which vary in number and character
in different species. In the spider-crabs the whole surface of the
carapace is generally studded with tubercles, spines, and stiff hairs
of a peculiar character. This armature is for protective purposes,
and is often used to secure foreign bodies, such as algæ, hydroids,
and polyzoans, which the crabs place upon their backs to disguise
themselves. The burrowing crabs are usually smooth. When in motion
the crab moves sideways, using the legs [pg274] of one side to pull
with and those of the other side to push with. As all the legs do
not move at the same time, a continuous and uniform motion is kept
up. Some species move with great rapidity, notably the sand-crab,
/Ocypoda arenaria/. Often when pursued they will run into the surf
instead of to their holes. The common edible crab, /Callinectes
sapidus/, of the Atlantic coast, the fiddler-crabs, and the
spider-crabs are among the well-known representatives of /Brachyura/.
FAMILY ~PORTUNIDÆ~
SWIMMING CRABS
GENUS ^Carcinides^
[Illustration: /Carcinides mænas/, the green crab.]
^C. mænas^ (M. J. Rathbun), ^Carcinus mænas^ (Leach), the green
crab. This is one of the most common species on the Atlantic coast
from Cape Cod to New Jersey, and is very abundant in Vineyard
Sound, Buzzard's Bay, and Long Island Sound. It is found between
tide-marks, frequently well up on the beach, hiding under loose
stones, also in tide-pools and in holes and cavernous places on
the shore. It is from one and a half to two inches long, and a
little more in breadth. It has five acute teeth on each side of the
anterior part of the carapace. Its color is green, spotted with
yellow, making it quite conspicuous. The surface of the carapace
and limbs is more or less granulated. The posterior feet are
flattened to form swimming-paddles. It is a very lively creature
and has reckless audacity when brought to bay, which justifies its
specific name (which implies frenzy). The French call it /crabe
enragé/. [pg275]
GENUS ^Callinectes^
[Illustration: /Callinectes sapidus/, the blue crab.]
^C. sapidus^ (Mary J. Rathbun), ^C. hastatus^ (Stimpson), the blue
crab. This is the common edible crab of the Atlantic coast. It is
known at the North as the "blue crab," and at the South as the
"sea-crab." It is found from Cape Cod to Florida, and after the
lobster is the crustacean which has the greatest commercial value,
being taken in immense quantities for the markets, not only when
the shell is hard, but immediately after moulting, before the new
shell has hardened, when it is known as the "soft-shelled crab."
It inhabits muddy shores, and is common in bays and at the mouths
of estuaries. The carapace is about twice as broad as it is long,
and has a long, sharp spine on each side which projects outward.
This is a distinguishing feature. There are eight short spines on
each side between the long spines and the eyes; then come recesses
for the eyes, and between the eyes are four unequal teeth and a
small spine underneath. The chelæ are large and somewhat unequal
in size; then come three pairs of simple feet and a fifth pair,
which are flattened, forming swimming-organs. The margins of the
carapace and abdomen are fringed with fine hairs, as are also most
of the joints of the limbs. The upper surface of the body and claws
is dark green in color, the lower surface is dingy white, the feet
blue, and the tips of the spines reddish. The body is compressed,
the carapace being moderately convex above, and is covered with
minute granulations, which are more numerous over some portions
than over others. The abdomen of the female is very broad and fills
the entire space between the bases of the posterior pair of feet.
During the spawning season it is so charged with eggs that often
it projects out almost at right angles with the carapace. The
[pg276] crabs of this species are very active and can swim rapidly.
They also have the habit of pushing themselves backward into the
mud for concealment. They are predaceous and pugnacious, and have
great strength in their claws, which they use with dexterity.
They not only fight their own kind, but show a bold front to all
enemies, including man. The average size is six inches across the
carapace.
GENUS ^Ovalipes^
[Illustration: /Ovalipes ocellatus/, the lady-crab.]
^O. ocellatus^ (Rathbun), ^Platyonichus ocellatus^ (Latreille),
the lady-crab or sand-crab. A species common on sandy shores from
Cape Cod to Florida. It is found among the loose sands at low-water
mark, even on the most exposed beaches, and also is abundant on
sandy bottoms offshore. At low-water mark it buries itself up
to the eyes and antennæ in the sand, where it watches for prey
and foes, and quickly disappears beneath the sand when danger
approaches. It possesses the power of burrowing in common with
other marine animals which inhabit exposed beaches of loose sand.
By burying itself deep in the sand it is protected from the action
of the breakers. This species is easily distinguished by the color
and shape of its carapace, taken in connection with its posterior
swimming-feet. The body is nearly as long as it is broad, with
five prominent spines on each side. The front margin is indented
on each side of a three-spined rostrum, to form cavities for the
eyes. The first limbs are large and have claws; the posterior ones
are flattened into swimming-feet, and the intermediate three pairs
are simple in structure, ending in points. In color it is white,
covered with spotted rings of red and purple. [pg277]
WALKING CRABS
FAMILY ~CANCROIDÆ~
GENUS ^Cancer^
[Illustration: /Cancer irroratus/, the rock-crab; male.]
^C. irroratus^, the rock-crab. This is the common crab of the New
England coast. It ranges from Labrador to South Carolina, but is
rare south of New Jersey. It is found on sandy as well as on rocky
shores at and below low-water mark and also between tide-marks,
hiding among rocks, nearly buried in sand or gravel, and in
tide-pools, where sometimes amusing combats between the males may
be seen. The carapace is suboval, one third broader than long,
the breadth being often from three to four inches. The surface is
granulated but smooth; the color is yellowish, closely dotted with
brown. The eyes are on short stalks in deep, circular holes, and
between the eyes are small teeth. There are nine blunt teeth along
each side of the front edge of the carapace. The first pair of legs
are short and stout, and terminate in claws. The four posterior
pairs are slender and end in pointed tips. This is an edible crab,
and it is devoured by the larger fishes, but does not—although
there seems to be no reason for it—share to any extent a place in
the markets with the blue crab, /Callinectes sapidus/.
[Illustration: /Cancer borealis/, the Jonah crab; male.]
^C. borealis^, the Jonah crab. This crab resembles, and is
frequently taken for, /C. irroratus/. It is larger than the latter
in full growth, and is heavier and more massive. The carapace and
claws are rougher, the granules being irregular in size. The legs
are proportionately shorter and heavier. The teeth on the anterior
margins are rounded in front, but the posterior ones are sharply
pointed. In color [pg278] it is brick-red above and yellowish
beneath. It inhabits rocky shores only and is found at low tide on
the surface of the rocks, where it is exposed to the action of the
waves and also to the attacks of birds of prey, which feed upon
it, while /C. irroratus/, concealed under the rocks in the same
locality, escapes their depredations. This species is supplied to
the Newport market, where it is considered preferable to the blue
crab. Its range is from the eastern end of Long Island to Nova
Scotia.
[Illustration: /Cancer magister/, the common crab of the Pacific
coast; male.]
^C. magister.^ This species inhabits the Pacific coast and ranges
from Alaska to Lower California. The adult male is from seven to
nine inches broad and from four to five inches long. The anterior
margin of the carapace is an almost regular elliptical curve with
nine small teeth on each side. At the end of the curve a large,
pointed tooth projects directly outward, and from this the carapace
slopes abruptly backward, giving a narrow posterior end. The
surface of the carapace is undulated and covered with papillæ, and
is light reddish-brown, shading to lighter color in the back. The
color of the legs and under surface of the animal is yellowish.
The claws are toothed above and ribbed at the sides. It inhabits
sandy bottoms below tide-mark and is the largest and most important
edible crab of the western coast.
^C. productus^, the red crab. This species, like the preceding one,
is of large size and inhabits the western coast from Alaska to
the Gulf of California. The carapace is four and a half inches in
length, from five to seven in breadth, and somewhat elliptical in
outline. The teeth on the anterior margin are distinctly separate
in the adult, but in the young appear as wrinklings of the edge
of the carapace. The posterior margins are concave. In color the
animal is dark red above and yellowish beneath in the adults, but
variable in the young, sometimes being yellow spotted with red,
or banded with red and yellow. It inhabits rocky shores. This is
an edible crab, but is not taken for the markets, /C. magister/
supplying all demands. [pg279]
[Illustration: /Cancer productus/, the red crab; male.]
[Illustration: /Cancer antennarius/, the California rock-crab.]
[pg280]
^C. antennarius^, the rock-crab of the Pacific coast. This
species of the California coast inhabits rocky bottoms below
low-water mark. The carapace is three and a half inches long by
five or six inches wide, and dark purplish-brown in color. The
chelæ are marbled with purplish spots and are nearly smooth. The
distinguishing features of this crab are its large and hairy
antennæ, the hirsute margins of its abdomen and walking-feet, and
the numerous hairs on the under side of its body.
GENUS ^Menippe^
[Illustration: /Menippe mercenaria/, the stone-crab; male.]
^M. mercenaria^, the stone-crab. This species lives in deep holes
in the mud along the borders of creeks and estuaries, and also
in crevices between fragments of rock, in stone-heaps and other
debris, and is found from South Carolina to Texas. These crabs are
edible, and in some localities are hunted for food, one manner
of capturing them being to thrust the hand and arm into their
holes and drag them out, an operation attended with danger to the
inexperienced hunter, who is likely to be badly pinched. They are
withdrawn with difficulty, as they offer a strong resistance,
bracing themselves with their claws against the sides of their
holes, and often hold so firmly to the rocks that they are torn
[pg281] apart. They are also taken by a hooked iron which is thrust
into the hole; the crab seizes it and is then suddenly jerked from
its hole. The adult measures about three by four and a half inches,
and the body is from one inch to two inches thick. One of the chelæ
is larger than the other, and both are proportionately enormously
large, and are tipped with black. The terminal joints of the other
four pairs of legs are thickly fringed with hairs and end in points
which seem like nails.
FORMER GENUS ^Panopeus^
[Illustration: /Eurypanopeus depressus/, the mud-crab; male, natural
size.]
^Eupanopeus herbstii^, ^Eurypanopeus depressus^, ^Neopanopeus
texana^, ^Rhithropanopeus harrisii^ (Mary J. Rathbun). These four
species, formerly all called /Panopeus/, are small crabs which live
in the mud and are commonly known as mud-crabs. They are abundant
under stones in muddy places, and occur on the Atlantic coast from
Massachusetts Bay to Florida, though they are not commonly met with
north of New Jersey. /Eupanopeus herbstii/ is the largest one of
the group, some of the Southern ones measuring two inches across.
It is found living in mud at low-water mark, or burrowing in banks
near high-tide mark. It is dark olive-brown, the claws broadly
tipped with black. /Eurypanopeus depressus/ is flattened above,
and is smaller than /Neopanopeus texana/, which is somewhat convex
above. The last two are commonly found together and have similar
habits. /Rhithropanopeus harrisii/ lives near high-water mark and
also in salt-marshes, and is comparatively rare. The claws lack the
dark tips of /E. herbstii/, and a distinct groove follows the edge
of the carapace.
FAMILY ~GRAPSIDÆ~
GENUS ^Hemigrapsus^
^H. nudus^ (Mary J. Rathbun), ^Heterograpsus nudus^ (Stimpson);
^H. oregonensis^ (Mary J. Rathbun), ^Heterograpsus oregonensis^
(Stimpson). These two species, commonly called respectively the
/purple shore-crab/ and the /yellow shore-crab/, are the most
abundant species of the California coast. Hundreds may be found
congregated under a single rock. They range from Sitka to Lower
California. /H. oregonensis/ literally swarms in sloughs of salt
or brackish water, and hundreds of uplifted threatening claws
confront the intruder who ventures on these mud-flats when the tide
is out. This species, the yellow shore-crab, has a nearly square
body. The anterior half of the side margins has two rather deep
indentations, [pg282] making two spine-like projections which bend
forward. The four posterior pairs of legs are more or less hairy;
the chelæ are rather large in proportion. The male is about one
inch across and the female is one third less in size. The general
color is yellow. /H. nudus/ is found in the same localities, and
differs from /H. oregonensis/ in being purple in color, with
mottled claws, and in having the denticulations less pronounced
and the walking-feet devoid of hairs. It is also a little larger.
(Plate LXIII.)
GENUS ^Pacygrapsus^
^P. crassipes.^ A species very common on the California coast south
of San Francisco. This crab is similar in general features to the
purple and yellow ones described above, but is considerably larger,
and the carapace is banded with color.
FAMILY ~OCYPODIDÆ~
GENUS ^Ocypoda^
^O. arenaria^, the sand- or ghost-crab. The name /Ocypoda/ means
"swift-footed," and, as it implies, this species is especially
noted for its rapidity of movement. These crabs are the opposite
of the strong-armed, thick-shelled, slow-moving /Cancroidæ/. An
instance is told of a collector having great difficulty to keep up
at full run with one which he chased for a considerable distance
over the sand. They are also dexterous in burrowing, and live in
holes, often three feet deep, dug perpendicularly into the sand.
They wander far from their burrows when the tide is out, and
every little while raise their stalked eyes and stand on tiptoe
to look about. If alarmed, they run with great rapidity to the
nearest burrow, or, if danger is close, press themselves on the
sand until an attempt is made to touch them, when they again dart
away rapidly, and in running hold their bodies high, and double
and dodge so that it is difficult to catch them. /Ocypoda/ is
colored almost exactly like the sand, and this mimicry, together
with its fleetness, makes it interesting to note and difficult
to capture. It inhabits sandy beaches above tide-mark from Long
Island to Brazil, and subsists largely upon the beach-fleas, which
inhabit the same localities. It springs upon them, very much as a
cat catches a mouse. The carapace of this species is almost square
in outline, and on the anterior corners ends in a spine. A small
portion of the carapace folds down like a band between the eyes. On
each side of this band, and extending across the front, are large
grooves for the eye-stalks. The body is about an inch thick; the
first joints of the chelæ are toothed; one chela is a little longer
than the other, and both are coarsely granulated. The other four
pairs of legs are thickly fringed with hairs. (Plate LXIII.)
[Illustration: PLATE LXIII. Hemigrapsus nudus. Hyas araneus. Ocypoda
arenaria. Pugettia gracilis. Libinia dubia. Pitho aculeata.]
[Illustration: /Uca/ (/Gelasimus/) /pugilator/, the fiddler-crab;
male.]
GENUS ^Uca^
^U. minax^ (^Gelasimus minax^), ^U. pugnax^ (^Gelasimus pugnax^),
^U. pugilator^ (^Gelasimus pugilator^), the fiddler-crabs. These
species [pg283] of fiddler-crabs occur on the Atlantic
coast. They congregate in immense numbers, and excavate their
holes in convenient localities above the reach of the tides—on
salt-marshes, far up the estuaries, and along the mouths of rivers,
even where the water is quite fresh. The males have one claw very
largely developed; the other chela is small. The former is likened
to a fiddle, the latter to a bow, and this, together with the
waving motion of the large claw, gives them their popular name.
This comparatively enormous claw is a distinguishing feature by
which they are easily recognized without other description. The
female has claws of small and equal size. These crabs burrow holes
in the mud or sand half an inch to two inches in diameter and a
foot or more in depth. The upper part is nearly perpendicular,
becoming horizontal below, with a chamber at the end. One species,
/U. minax/, constructs an archway over the mouth of its burrow, in
which it sits and surveys the surroundings, but quickly retreats
when danger approaches. The crab makes its burrow by scraping up
the mud or sand and forming it into pellets, which it carries under
the three anterior walking-feet on the under side, using the legs
on the side moving forward, and the fourth one on the other side,
to climb out of the hole. After peering cautiously about, the
crab emerges, and carries its load four or five feet away before
dropping it; then again looks about before quickly running back;
and, finally, turning its stalked eyes, looks in all directions
and suddenly disappears, soon to return with another load. The
burrows cover considerable areas, and the crabs are so abundant
that the marshes and shores sometimes seem to be alive with them.
When alarmed, they lift the large claw and run sideways, after
the manner of all crabs, to their holes, and, as many are likely
to retreat into the most convenient one, the owner often finds
his burrow occupied by other tenants, whom he unceremoniously
proceeds to pull out. /U. minax/ ranges from southern New England
to Florida, and lives on salt-marshes farther away from the sea
than the others, and often where the water is quite fresh. It
is larger than the other species, and can be distinguished by a
red patch at the joints of the legs. It is a vegetarian in diet,
living on small algæ. This is the species which constructs a little
observation-house over the mouth of its burrow. It can live out of
water, and without food, for several days. /U. pugilator/ lives
on sandy and muddy flats and beaches near high-water mark, where
the sand is compact and somewhat sheltered, and ranges from Cape
Cod to Florida. This species, like /U. minax/, is a vegetarian.
/U. pugnax/ is exceedingly abundant on muddy banks and ditches of
salt-marshes, the banks being sometimes completely honeycombed and
undermined by them. It ranges from Cape Cod to Florida. [pg284]
FAMILY ~MAIIDÆ~
The members of this family are known as "spider-crabs." Their bodies
are thick and more or less round in form, narrowing in front to
a long, beak-like projection. The surface is generally rough and
irregular, having tubercles, spines, prickles, and hairs. The legs
are long. These crabs are often covered with seaweeds, hydroids,
and other organisms, which they gather with their long and flexible
chelipeds and place upon their backs, presumably to conceal
themselves from their enemies. They seem to select, instinctively or
with reason, such things as will bear transplanting, sometimes using
sponges and polyps which are not destroyed by being torn apart, and
they also select their dress with reference to its masking uses. A
/Hyas/ covered with bright-colored algæ was seen to remove them and
replace them with sponges, when transferred to the locality of the
latter, where the former did not grow. The animal takes in his claw
the object he has gathered, and first holds it to his mouth, where it
is moistened with a secretion of mucus or cement, and then places it
on his back. If it does not hold, the operation is repeated, often
several times, a new spot on the shell being selected each time. It
has also been found that the coats of these crabs are covered with
hairs which are differently arranged in different genera, some being
hooked, others serrated, etc., and that these aid in holding the
transplanted organisms in place. The crab is sometimes so covered
with these growths as to be entirely concealed beneath them. It is a
sluggish animal, and inhabits shallow water along the whole of the
Atlantic and Pacific coasts.
GENUS ^Libinia^
^L. dubia^, ^L. emarginata^. These two species inhabit the
Atlantic coast, and are found on muddy shores and flats, among
decaying seaweed, in eel-grass, and even beneath the surface of
the mud. They are covered with hairs, and sometimes have planted
on their backs algæ, hydroids, and even barnacles. The legs of /L.
emarginata/ often spread a foot or more. The males are much larger
than the females. The species ranges from Maine to Florida. /L.
dubia/ does not extend north of Cape Cod. It is found more commonly
than /L. emarginata/ in very shallow water [pg285] near shore. It
is not so thickly covered with spines, and has a longer rostrum,
which is also more deeply divided at the end. (Plate LXIII.)
GENUS ^Hyas^
^H. coarctatus^, the toad-crab. This species of spider-crab is
found from Greenland to New Jersey, in shallow as well as in deep
water. Its body resembles strongly, both in form and size, that of
a toad, hence its common name. It forms an important part of the
food of the cod.
^H. lyratus.^ A toad-crab of the Pacific coast, ranging from Bering
Sea to Puget Sound; named from the lyre-shape of its carapace.
^H. araneus.^ A species which especially resembles a toad in its
form. Found off the northern New England coast. (Plate LXIII.)
GENUS ^Loxorhynchus^
^L. crispatus^, the sheep-crab. This crab occurs on the coast of
southern California. The body is thick and about three inches
across the widest portion, and tapers to a long, prominent rostrum.
It is covered with long tubercles and spines and with short,
bristly hairs; the legs are long, the chelipeds stretching fully
two feet.
GENUS ^Pugettia^
^P. gracilis.^ A small spider-crab found on the Pacific coast from
Alaska to Puget Sound. Its body is one half of an inch wide and
[pg286] one inch long, with prominent spines on the sides of the
carapace, which narrows in front into a long beak ending in two
spines. It is red and green above, red beneath. (Plate LXIII.)
GENUS ^Sternorhynchus^
^S. sagittarius.^ This is one of the most delicately formed of the
spider-crabs. The body has narrow longitudinal stripes of light and
dark color. It lives offshore from Cape Hatteras southward.
[Illustration: /Epialtus productus/, the kelp-crab; female.]
GENUS ^Epialtus^
^E. productus^, the kelp-crab. This crab inhabits the coasts of
California and Oregon, and is found among seaweeds on rocks just
below low-water mark. The carapace is smooth, is quadrate in form,
is about two inches long and broad, has two spines on each side,
and has a prominent denticulated rostrum. This is the most common
spider-crab of the Pacific (California) coast. It is olive-green,
thus simulating in color the kelp among which it lives. (See page
285.)
GENUS ^Pitho^
^P. aculeata.^ The carapace has six spines on each side, the
middle two being sometimes partly united; the general outline is
pentagonal; the length about one inch. Quite common on the Florida
coast. (Plate LXIII.)
GENUS ^Lambrus^
[Illustration: /Lambrus pourtalesii./]
^L. pourtalesii^, the long-armed spider-crab. The carapace is
broader than it is long and has three elevations all covered with
spines. The general surface is pitted and granulated; the rostrum
points downward; the chelipeds are very long, the margins armed
with spines; the breadth of the carapace is about one and a half
inches; and the length of the chelipeds is about three and a half
inches. Its range is from Cape Cod to Florida, and it lives among
the rocks. (Plate LXIV.) [pg287]
FAMILY ~CALAPPIDÆ~
GENUS ^Calappa^
^C. flamma^, the box-crab. This singular animal lives on sandy and
muddy bottoms offshore, from North Carolina southward. The carapace
is broad and straight on the posterior side, and is curved on the
anterior side, narrowing to the front. The posterior side has
prominent denticulations. The body is one and a half inches thick,
about four to five inches wide, and two to three inches long.
The chelæ are large, broad, and flattened, and are so arranged
that when flexed they fit closely together across the front. When
folded, and the small legs are withdrawn under the carapace, the
animal is shut up as if in a box, and resembles a shell. When in
danger it closes its doors, as it were, and abandons itself to the
waves, which often carry it ashore. The crested claws resemble the
head of a cock. (Plate LXIV.)
FAMILY ~PINNOTHERIIDÆ~
GENUS ^Pinnotheres^
[Illustration: /Pinnotheres ostreum/, the oyster-crab; male, enlarged
four diameters.]
^P. ostreum^, the oyster-crab. The female of this species lives
in the gill-cavity of the oyster, and is particularly abundant in
oysters from the Chesapeake. The males are seldom seen, and rarely
occur in the oyster, but swim freely about. They are smaller than
the female, have a firmer shell, and are dark brown above, with a
dorsal stripe and two conspicuous spots. The under side of the legs
is whitish. The female is commensal, at least in the adult form,
and its thin, whitish, transparent carapace is tinged with pink.
The species ^P. maculatum^ lives in /Mytilus edulis/ (mussel) and
in the smooth scallop, /Pecten magellanicus/. The oyster-crab is a
true messmate, and its presence in the oyster may be advantageous
in helping to provide food for its host. This crab, like the rest,
holds its eggs in the posterior feet until hatched, when the larvæ
leave the parent and swim about for a while. The females, at the
megalops stage, enter oysters—sometimes two enter the same oyster,
but seldom more than one; there it remains permanently, growing to
the size of an inch or more in diameter, and becomes a degenerate.
The eyes become smaller; the shell never hardens, like its allies
which live in open water; its limbs and chelæ are weak; and it has
no pugnacity, the protection afforded by the oyster doing away with
the need for the common protective features of its kind. /Pinnixa
cylindrica/, a related species, lives in the tubes of large annelid
worms as a commensal. [pg288]
ORDER =STOMATOPODA=
GENUS ^Squilla^
[Illustration: /Squilla empusa/, the mantis-shrimp.]
^S. empusa.^ This animal suggests somewhat the lobster, though very
unlike it. The carapace is much smaller and softer, and leaves
the last three segments of the thorax uncovered. The abdomen is
larger and longer in proportion, while the legs and organs are
quite different. The whole body is depressed, instead of laterally
compressed. It measures from eight to ten inches in length and two
inches in breadth. Instead of chelæ, the last joint of the great
claw has six sharp curved spines, which fit into sockets in a
groove on the second joint. By this singular organ they hold their
prey securely. The abdominal feet carry the gills. The antennal
scales are oblong and fringed with hair. The antennules terminate
in three flagella. The caudal appendages and telson are long,
strong, and armed with spines. This animal lives in burrows in the
mud below low-water mark, forming large, irregular holes, but is
frequently washed ashore. In color it is pale yellowish-green, each
segment being bordered with darker green and edged with yellow. It
is found from Cape Cod to Florida.
ORDER =CUMACEA=
GENUS ^Diastylis^
^D. quadrispinosus.^ Among the minute /Crustacea/ which swim on the
surface of the water, this species, with other small forms, may be
captured by using a muslin net. It is a quarter of an inch or less
in length. It is easily distinguished by its large carapace, the
posterior portion of which is marked off in transverse ridges, the
anterior end running into a sharp-pointed rostrum. It has a long,
slender abdomen, the sections of which [pg289] are distinctly
marked, and it terminates in long, forked spines, which are longer
than the telson. It is found from New Jersey northward.
ORDER =ARTHROSTRACA=
SUBORDER ~AMPHIPODA~
The /Amphipoda/ have a laterally compressed body, with gills on the
thoracic feet and an elongated abdomen. The segments of the thorax
are not united, nor covered by a carapace, but the whole body is
covered with a segmented, polished, flexible cuticle. The three
anterior legs of the abdomen are for swimming-feet, and the posterior
ones are adapted for springing. The antennæ are long and hairy. The
amphipods comprise the beach-fleas and many other small crustaceans
which abound between tide-marks on all beaches. Besides serving in no
small measure as food for fishes, they are scavengers of the beach,
and consume large quantities of waste matter. They are sometimes
used in preparing skeletons for anatomical specimens. Animals to be
skeletonized, being fastened to boards and anchored just below the
surface of the water in sheltered places, are divested of all flesh
in a few hours, and the bones are more completely cleaned than if
prepared by a naturalist.
GENUS ^Orchestia^
[Illustration: /Orchestia agilis/; male.]
^O. agilis^, the beach-flea. These little crustaceans exist in
countless numbers under the masses of sea-wrack on the beach. When
disturbed they jump about with great agility by means of the last
three pairs of abdominal feet, which are adapted to this purpose.
In color the animal is brown and much resembles the decaying
seaweeds among which it lives and upon which it probably feeds. The
antennules are short, the antennæ long, on two long, jointed bases.
The second pair of feet in the males terminate in chelæ. The last
abdominal appendages are stiff and pointed backward. The abdomen is
curved under. The length of /Orchestia/ is half an inch or less.
Some species occur on all beaches. /O. agilis/ ranges from New
Jersey to Greenland.
GENUS ^Talorchestia^
^T. longicornis^ (^Talitrus longicornis^). This species is similar
to Orchestia agilis, but is about an inch long when mature and
of a paler [pg290] color. It jumps like the latter, but not so
strongly. It is found among the weeds and burrowing in the sand
a little below high-water mark. The wet sand is often completely
filled with its holes. It can be distinguished by its very long
antennæ. Another species, ^T. megalophthalma,^ is distinguished by
its shorter antennæ and very large eyes. Both of these species are
grayish in color and closely resemble the sand. Found from Cape Cod
to New Jersey.
GENUS ^Gammarus^
[Illustration: /Gammarus locusta/, the scud.]
^G. locusta.^ The animals of this genus are among the largest of
the amphipods. The males are larger than the females, sometimes
being one and a half inches long. They are abundant under stones
and /Fucus/ at and near low-water mark. Although much larger than
the beach-fleas, they otherwise resemble them. They do not jump
like the former, but move rapidly, lying on the side, and in water
swim with the back downward. Two pairs of the thoracic feet are
chelate, and three pairs are longer than the others. The feet
on the last segments of the abdomen are stiff and turn sharply
back, forming a part of the tail, which is used most effectively
in locomotion. The antennules and antennæ are of about the same
length. Several species of /Gammarus/ occur in the same range, all
having the same general characteristics; some have but one pair of
chelate feet; the antennules are usually shorter than the antennæ;
the females of all the species have no chelate feet. /G. locusta/
ranges from New Jersey to Greenland. The color is generally
reddish- or olive-brown. ^G. annulatus^ is found in the same
places, but usually a little higher up on the beach; it is lighter
in color, and has dark bands with red spots on the sides of the
abdomen. ^G. mucronatus^ occurs from Cape Cod to Florida. ^Melita
nitida^ is a smaller slate-colored amphipod found in some places;
another is ^Mœra levis^, which is whitish, with black eyes.
[Illustration: /Chelura terebrans/, the boring amphipod.]
GENUS ^Chelura^
^C. terebrans^, the boring amphipod. This little crustacean
is associated in its work on submerged timber with the isopod
/Limnoria lignorum/. The excavations of the latter are narrow and
cylindrical, running down into the wood, while /Chelura/ makes
larger burrows in oblique lines near the surface, which give the
wood the appearance of having been plowed. It is very active and
destructive. It feeds upon the wood into which it burrows. Its
color is semi-translucent, thickly mottled above with pink. [pg291]
GENUS ^Caprella^
[Illustration: /Caprella geometrica./]
^C. geometrica.^ These very curious little animals, which are so
slender as to seem like skeletons, are found in abundance clinging
to hydroids, /Polyzoa/, delicate algæ, or eel-grass, or under
stones in tide-pools. They resemble in color, and often in form,
the objects on which they live. Holding on by the posterior feet,
they extend the body out rigidly or sway it about, so that they
resemble little sticks or branches, and often escape detection. In
walking, they bring the hind feet up to the front ones, doubling
the body into a loop like the canker- or measuring-worm. The
appendages on the anterior and posterior ends are furnished with
chelæ and hooks; those of the middle section are rudimentary. This
animal cannot be mistaken for any other. /C. geometrica/ is found
from Cape Cod to North Carolina. Some of the species of this genus
may be found on every coast.
SUBORDER ~ISOPODA~
The isopods have an elongate, flattened, but more or less arched
body, composed of seven thoracic segments and a short abdomen of
six segments. The six segments of the abdomen are smaller than
those of the thorax, and are often more or less united, sometimes
into a single piece with scarcely any trace of division above; but
the number of pairs of appendages is generally six, showing the
composite nature of the apparently simple organ. The last segment,
or telson, is broad and has a pair of modified appendages. The seven
thoracic legs are not all equal, as the name would imply, but vary
greatly in different species. As a rule, they are adapted to walking
or attachment, and in the female some have delicate plates which
form brood-pouches. The swimming-feet fold under the abdomen, and
in some species are inclosed by the first pair, which are large and
plate-like, and form a complete cover for the others. The isopods
are a large and widely distributed order, varying in size, and
are inconspicuous because they cling closely to objects. They are
retiring in habit, though extremely ferocious.
The sow-bugs or pill-bugs, common in gardens, under leaves in the
woods, and under almost any pile of rubbish among decaying vegetable
matter, are a land species of isopods. Other species inhabit [pg292]
ponds and streams of fresh water, and still others are found along
the shores of all oceans, abounding among the marine vegetation
of the shallow waters. Some swim free in the open sea; others are
brought up from the greatest depths. Others, again, are parasites,
and live in the internal organs of fishes and prawns. Sometimes
a prawn is found having what appears like a very swollen throat,
which actually is a little parasitic isopod of the family /Bopyridæ/
attached to its gills.
GENUS ^Cirolana^
[Illustration: /Cirolana concharum./]
^C. concharum.^ The body consists of fourteen segments, the first
being the head, the next seven the thorax, and the last six the
abdomen. On the head are the triangular eyes, the antennules, and
the antennæ, and underneath is the mouth, which is covered by the
maxillipeds. The dorsal surface is more or less rounded. At the
bases of all the segmental thoracic rings excepting the first one
are sutures marking off square, scale-like pieces (/epimera/). The
epimera form a border to the side margins. The legs are attached to
the epimera, which are, in fact, the upper segments of the legs.
The first three pairs of legs have a general resemblance to one
another, and are directed forward. The last four pairs are much
longer and flatter, and are directed backward. The telson, or last
segment, is triangular, and the square or blunt apex is fringed
with hairs. On the ventral surface of the thorax in the adult
females there is a long pouch for the reception and development
of the eggs. This species is usually about one and a half inches
in length, but sometimes is longer. Its color is yellowish, with
a brown edge on the posterior margins of the segments, somewhat
translucent in the thinner parts. It is found from Cape Cod to
South Carolina, swimming about in shallow water, and is especially
abundant in winter.
GENUS ^Limnoria^
[Illustration: /Limnoria lignorum/, the gribble.]
^L. lignorum^, the gribble. This little isopod is very destructive
in its habits, boring into submerged woodwork, like the ship-worm
(Teredo), and doing great damage to the piles of wharves, etc. It
burrows to the depth of half an inch, and completely honeycombs
the surface of the wood, which then scales off or rapidly decays,
and is washed away by the waves. The animal then begins anew,
and in a short time, or at the rate of about an inch a year,
piles diminish in diameter where /Limnoria/ is plentiful, and are
finally destroyed unless protected from these little crustaceans
by a sheathing of metal. Although considered as pests, they have
an economic value not so often recognized, as they attack all
driftwood, and in time entirely destroy floating and water-logged
[pg293] timber, which without their destructive agency might become
serious obstructions to navigation. /Limnoria/ is only the fifth
of an inch in length, and its back is covered with minute hairs,
to which dirt usually adheres. It burrows with its mandibles, or
jaws, which are chisel-like at the ends. Its habitat extends from
a little above to a little below tide-marks throughout the whole
Atlantic coast.
GENUS ^Sphæroma^
^S. quadridentatum.^ The name of the genus to which this species
belongs is derived from the peculiar habit of many of the species
of rolling themselves into a ball when alarmed. The body is so
constructed as to admit of this singular change of shape. The
abdomen turns under, and the last abdominal appendages, together
with the narrow epimera, shut in the legs and cover the ventral
portions with armor. The body, when extended, is an ellipse a
little over a quarter of an inch in length and half that in
breadth. The legs are hairy and adapted to walking. The anterior
abdominal segments are fused into one, but are marked at the sides
with depressed lines. The abdominal feet are plate-like and fringed
with hairs. A slight elevation runs around the margins of the
animal like a border. The color is variable. Some are a uniform
slaty gray; others are marked with a longitudinal patch of color
on the back. It is found from Cape Cod to Florida among algæ or
rocks, and is easily recognized by its habit of rolling itself
into a ball. ^Sphæroma destructor^ is a boring isopod, larger than
/Limnoria/, and is even more destructive, since its holes are
larger; but its range is limited, or, at least, it has so far been
found only in the St. Johns River, Florida.
[Illustration: /Sphæroma quadridentatum./]
GENUS ^Idotea^
[Illustration: /Idotea marina./]
^I. marina^ (Linnæus), ^I. irrorata^ (Edwards). This species is
about one inch long, and is easily recognized by the abdomen, the
first three segments of which are narrow and terminate in acute
teeth, while the other three are fused into one with straight sides
and ending in three teeth, of which the middle one is the longest.
The first pair of abdominal feet are large, long, and plate-like,
covering the other feet and whole under surface of the abdomen like
an operculum. The head is nearly square, the eyes are small, and
the antennæ have long peduncles. The articulations of the thoracic
feet are fringed with hair. The color of this species varies:
sometimes it is light or dark green, or brown with black spots;
again [pg294] it is striped longitudinally with light color.
Sometimes the stripes run transversely in bands or spots. It is
found from New Jersey northward on rocky shores of bays and sounds,
or in eel-grass on sandy shores.
^I. ochotensis.^ A species very similar to the preceding, but a
little larger, found on the Pacific coast.
^I. metallica.^ This species is a little smaller than /I. marina/,
and differs from it in having the end of the telson truncated, or
straight, instead of dentate. The head is nearly square. The body
is broadest in the middle of the thorax; the projecting epimera
give a serrate appearance to the sides. The abdominal feet are
inclosed in the operculum-like scales of the first pair of feet.
Its color is bright blue or green, often with a metallic luster
when seen in the water. It is found swimming free or floating in
masses of seaweeds from Long Island northward and also on the
Pacific coast.
^I. wosnesenskii.^ A common species on the California coast,
about one inch long and dark in color. The abdominal segments are
united and bluntly rounded, and each has a small median tooth. The
abdominal feet are inclosed by the opercular feet. Eggs and young
are carried in a pouch.
GENUS ^Chiridotea^
[Illustration: /Chiridotea cæca./]
^C. cæca.^ This species burrows beneath the surface of the sand,
raising it up into a little ridge, and makes a mound at the end of
the burrow, where it may be found. These trails are common on the
wet sand. It imitates the sand in color, and is about half an inch
in length, with a broad thorax and narrow abdomen terminating in a
point. It is found on the New England coast.
^C. entomon^ (Linnæus). This species of the northern Pacific coast
is from one to three inches long. The head has the appearance of
two lobes, the sides having two rounded ends. The body is broad,
the abdomen narrowing to a pointed end. The last segments of the
abdomen are united, and the abdominal feet are inclosed by the
first pair, which extend over them like an operculum. The epimera
are broad, with acute lateral angles.
CLASS =MERISTOMES=
ORDER =XIPHOSURA=
GENUS ^Limulus^
[Illustration: Under surface of horseshoe-crab, /Limulus polyphemus/:
/a/, abdomen; /c/, cephalothorax; /g/, the first gill-bearing
abdominal appendage; /m/, mouth; /o/, operculum; /p/, telson; /s/,
metastoma; 1-6, cephalothoracic limbs.]
^L. polyphemus^, the horseshoe- or king-crab. This well-known
and curious animal ranges along the Atlantic coast from Maine
to Mexico. [pg295] It lives on sandy and muddy shores below
low-water mark, where it burrows beneath the surface. At the
breeding season—May, June, and July—it comes ashore to deposit
its eggs near high-water mark. The crabs come up the beach in
pairs, the male being the smaller and riding on the back of the
female, holding on by short feet provided with nippers, which
are peculiar to the males. Sometimes the female is accompanied
by several males, each one holding on to the tail of another and
forming a string of animals. After the female has deposited her
eggs in a hole excavated by her for the purpose, the male covers
them with milt, and they then return to the water, leaving the
eggs to be buried in the sand by the action of the waves. The eggs
hatch in July and August, and sometimes the beach is literally
alive with the young crabs, which, however, soon disappear, and
are not seen again until they are well grown. After the spawning
season the adults are not very often seen, but usually their empty
shells, abandoned in moulting, may be found on the shore. The
horseshoe-crab, also called king-crab, is especially interesting
from the fact that it is the last survivor of an otherwise extinct
group of animals. Its relationships with classes which have become
extinct, its nearest relatives being fossils, make it difficult
to classify definitely with existing forms. Formerly it was
regarded as a crustacean; now it is classed by some authors with
the /Arachnida/, along with scorpions and spiders. It has the
characteristics of both groups. There are only two known species of
/Limulus/ in the world; the other, ^Limulus moluccanus^, lives on
the eastern coast of Asia. /L. polyphemus/ often measures a foot in
diameter. The body is composed of three parts. The front portion,
or cephalothorax, is broad and semicircular, with posterior angles
ending in points. Near each side of its dorsal surface is a pair of
large compound eyes covered with thickened cuticle, and near the
center line of the shell, at the base of the first spine, a pair
of small, simple eyes. The second portion is the abdomen, and the
third a long, movable spine attached to the last segment of the
abdomen and between two terminal points of the horn-like covering.
[pg296] On the cephalothorax are seven pairs of appendages. The
first pair are small and lie in front of the mouth; these and
the four following pairs have chelæ, or claws. The sixth pair
have no chelæ, but at the base have a peculiar process termed the
flabellum. These six pairs of appendages surround the mouth, and
have bristles at the base which serve as jaws. The seventh pair of
thoracic appendages are broad plates called the operculum, which
meet and cover the abdominal appendages to a certain extent. The
abdomen has five pairs of appendages, which are plate-like and
resemble the operculum in form and have an upper and an under
piece. On the posterior surfaces of the abdominal feet are large,
leaf-like folds, which are the gills. In front of the first pair
of thoracic legs is a small tubercle supposed to have an olfactory
function. /Limulus/ has a blood-vascular system (the blood being
bluish in color), a nervous and a digestive system. It walks with
the thoracic feet and swims with the abdominal ones. It enters
the sand by pushing in the rounded, anterior end. In moulting the
carapace opens on the front edge. /Limulus/ is edible, its meat
being, it is said, as good as that of the lobster. (Plate LXIV.)
CLASS =PANTOPODA= (Lang)
ORDER =PYCNOGONIDA=
This order of animals, like /Limulus/, has no definitely determined
position in the classification of marine organisms. About one hundred
and fifty species of /Pycnogonida/ have been described, of which
thirty are found on our coast and are commonly known as sea-spiders.
They are found crawling slowly over seaweeds, hydroids, and sponges,
and appear to be all legs, but, like other animals, have a digestive,
a circulatory, and a nervous system. They are devoid of organs of
respiration. The body has a cephalothorax, which bears a conical
suctorial proboscis on the anterior end, and on top a prominence
containing four eyes. It has three pairs of appendages, two pairs
of which are sometimes lacking; then come three free segments and
a rudimentary abdomen. There is a pair of short appendages bearing
claws (chelæ) and four pairs of long walking-legs. The walking-legs
contain a tubular outgrowth of the body, into which the stomach
extends. The egg-sacs are in the legs, and open at the basal joints.
The male is provided with an extra pair of legs, for the purpose of
carrying the eggs after they are deposited by the female. The
[pg297] ovigerous legs are run through sac-like pockets and bent
under the body, and thus the eggs are carried until hatched.
[Illustration: PLATE LXIV. Calappa flamma. Calappa flamma, claws
open, showing form of cockscomb. Lambrus pourtalesii. Limulus
polyphemus.]
GENUS ^Phoxichilidium^
^P. maxillare.^ This species is found on the New England coast
creeping over hydroids and ascidians. It is purple, gray, or brown
in color. Its young take shelter in the cavities of hydroids,
forming galls.
[Illustration: /Phoxichilidium maxillare/, enlarged.]
VII
MOLLUSCA
TABLE SHOWING THE CLASSIFICATION OF THE MOLLUSKS DESCRIBED IN THIS
CHAPTER
Phylum =MOLLUSCA=
Class =AMPHINEURA= (/Bilaterally symmetrical mollusks, having
shell composed of eight plates, or devoid of shell. Including
chitons and their allies/)
Order =POLYPLACOPHORA= (/Shell composed of eight plates/)
Order =APLACOPHORA= (/Devoid of shell/)
Class =GASTEROPODA= (/Unsymmetrical univalve mollusks, usually
spirally coiled. Periwinkles, whelks, snails, etc./)
Order =OPISTHOBRANCHIATA= (/Branchiæ, when present, behind
the heart/)
Suborder =TECTIBRANCHIATA= (/Branchiæ more or less covered
by mantle; shell delicate and often rudimentary/)
Suborder =NUDIBRANCHIATA= (/Devoid of shell and mantle, and
without true branchiæ/)
Order =PROSOBRANCHIATA= (/Branchiæ situated in front of the
heart/)
Suborder =DIATOCARDIA= (/Usually two auricles, two
branchiæ, and two nephridia/)
Suborder =MONOTOCARDIA= (/One auricle, one branchia, one
nephridium/)
Order =PULMONATA= (/Air-breathing mollusks/)
Class =SCAPHOPODA= (/Mollusks without head, eyes, or heart,
with trilobed foot and tubular shell open at both ends. The
tooth-shells/)
Class =PELECYPODA= (/Bilaterally symmetrical, headless, bivalved
mollusks. Mussels, cockles, oysters, etc./)
Order =PROTOBRANCHIATA= (/Gills form a single pair of
plume-like organs, each with two rows of flattened
gill-filaments/)
Order =FILIBRANCHIATA= (/Two pairs of plate-like gills formed
of V-shaped filaments/)
Order =PSEUDOLAMELLIBRANCHIATA= (/Gills plaited so as to form
vertical folds/)
Order =EULAMELLIBRANCHIATA= (/Firm, basket-work gills, the
filaments united by vascular connections/)
Class =CEPHALOPODA= (/Mollusks of high organization, having
a definitely formed head surrounded by tentacles; shell,
when present, usually internal; shell, external in nautili.
Cuttlefishes, squids, octopi, and nautili/)
Subclass =Tetrabranchiata=
Subclass =Dibranchiata=
Order =OCTOPODA=
Order =DECAPODA=
[pg302]
TERMS USED IN DESCRIBING MOLLUSKS
^Abductor muscles^: Muscles which move parts away from the axis.
^Adductor muscles^: Muscles which draw parts together; opposite of
/abductor/.
^Aperture^: Opening of the spiral shell.
^Bilateral symmetry^: Having two equal sides, divided by a central
axis.
^Branchiæ^: Gills, or breathing-organs; organs subservient to
respiration through water. Same as /ctenidia/.
^Buccal mass^: The mouth-parts as a whole; the organ of prehension
and mastication of food; the pharynx: present in all mollusks except
lamellibranchs.
^Canal^: A narrow prolongation of the aperture of a spiral shell.
^Carinated^: Ridged as if keeled; having a keel.
^Cinereous^: Ash-gray; having the color of wood-ashes.
^Cirri^, plural of ^Cirrus^: Filamentous appendages.
^Columella^: An upright pillar in the center of most of the univalve
shells, round which the whorls are convoluted.
^Concrescent^: Growing together; uniting.
^Cordate^: Heart-shaped.
^Costæ^, plural of ^Costa^: Ridges of a shell.
^Crenulated^: Having a series of notches; marked as with notches, as
the indented margin of a shell.
^Crystalline style^: A transparent gelatinous substance of unknown
function, which fills, at times, the stomach-parts of certain
mollusks.
^Ctenidia^, plural of ^Ctenidium^: Gills, or breathing-organs,
adapted to water-respiration. [pg303]
^Decussated^: Crossed; intersected.
^Dextral^: Having the aperture on the right side of the shell when
the apex is upward.
^Epidermis^: The horny coating or outer skin of some shells.
^Foot^: The ventral surface of the body on which the animal rests or
moves.
^Fossette^: A little hollow or pit.
^Fuscous^: Brown tinged with gray; swarthy.
^Fusiform^: Tapering both ways from the middle.
^Lamelliform^: Lamellate in structure; disposed in leaf-like layers.
^Lingual ribbon^: The chitinous band of teeth, or rasp, borne upon
the odontophore; the radula.
^Lunule^: An impressed area just below the beaks of bivalve shells.
^Mantle^: A fleshy or membranous outgrowth of the outer body-wall;
also called /pallium/.
^Mantle cavity^: The space between the mantle and the body.
^Monomyarian^: Having one adductor muscle, as an oyster.
^Nephridium^: The renal organ of mollusks, corresponding to kidneys
in vertebrates.
^Node^: A knob or protuberance; also a notch in the margin.
^Odon´tophore^: The lingual ribbon bearing chitinous teeth.
^Oper´culum^: A horny or shelly plate which serves to close the
aperture of the shell when the animal is retracted.
^Osphra´dia^, plural of ^Osphradium^: Olfactory or water-testing
organs.
^Otocyst^: The cavity, or cyst, which contains the essential parts of
an organ of hearing.
^Pallial line^: The impression or mark made by the mantle, or
pallium, on the inner surface of a bivalve shell.
^Pallial sinus^: A notch or recess of the pallial line; the scar of
the siphon.
^Papillaceous^: Warty; studded with bosses; having excrescences.
^Perios´tracum^: Same as /epidermis/.
^Per´istome^: In zoölogy, mouth-parts in general; in conchology, the
margin of the aperture of the shell. [pg304]
^Porcelanous^: Resembling porcelain.
^Rad´ula^: Same as /lingual ribbon/.
^Reticulated^: Having distinct lines or veins crossing like a
network; covered with netted lines.
^Sculpture^: Elevated or impressed marks on the surface; markings
resulting from irregularity of surface; tracery.
^Sinistral^: Having the aperture of the shell at the left; opposite
of /dextral/.
^Sinuate^: Curved in and out; wavy.
^Siphon^: A tubular fold, or prolongation of the mantle forming a
tube.
^Spire^: All the whorls of a spiral univalve, above the first large
body-whorl.
^Suture^: The line of junction of the successive whorls of a univalve
shell, or the line of closure of the opposite valves of a bivalve
shell.
^Teeth^: Tooth-like projections on the hinge of a bivalve shell.
^Testaceous^: Having a hard shell, as distinguished from crustaceous,
or soft-shelled.
^Turbinate^: Shaped like a whipping-top; whorled from a broad base to
an apex.
^Umbilicus^: A central, navel-like depression in the body-whorl; a
circular, more or less central pit or hollow.
^Umbo^: The beak of a bivalve shell; the protuberance of each valve
above the hinge.
^Varices^, plural of ^Varix^: Raised marks on the shell denoting a
former position of the lip of the aperture, and indicating periods of
rest.
^Varicose^: Having prominent and tortuous formations on the shell.
^Ventricose^: Having the whorls of the shell swollen or strongly
convex.
^Whorl^: One of the turns of a spiral shell. /Body-whorl/, the last
whorl.
[pg305]
MOLLUSKS
We now come to another large and important group of animals, with
characters so peculiar to itself and differing so radically from
those which distinguish any other class of living creatures, that
it may be said to occupy almost a unique position in the animal
kingdom. Recent investigations have demonstrated that the larval
form of mollusks presents some remarkable points of similarity to
the embryonic forms of the /Annelida/ and to the larvæ of some other
classes of lower organisms. This discovery is one of the triumphs
of embryology in its patient search for that connecting-thread that
weaves together all the varying forms of animal life. Aside from
these subtle evidences of relationship revealed by the microscope,
the mollusks appear to occupy a position of considerable isolation in
the biological world.
As accepted by zoölogists to-day, this phylum is but the remnant of
its former self. Aristotle considered all creatures with a testaceous
covering to belong to a single family, and those later patriarchs of
biology, Linnæus, Cuvier, and Lamarck, extended the group to include
the greater part of all the marine invertebrate animals. Little by
little the phylum has been shorn of orders and classes. First, the
worms and the /Echinodermata/ were separated into distinct phyla;
then the barnacles were discovered to be crustaceans, and were
accordingly removed from their position as "multivalves" under the
/Mollusca/; then the tunicates, or ascidians, were found, through the
critical examination of their larval stage, to be merely masquerading
as mollusks; and lastly, the brachiopods have been somewhat
reluctantly removed from their old position with the mollusks and
given the [pg306] distinction of a phylum almost exclusively to
themselves: they retain their old associations only in the name of
/Molluscoida/.
With some exceptions, all mollusks secrete from their outer skin, or
mantle fold, a calcareous protective covering, or shell. This may be
either "univalve" or "bivalve" according as it consists of one or two
pieces. This phylum includes all the sea-shells which are so commonly
found along every ocean beach, in the tide-pools, on rocks at low
tide, in estuaries, and, indeed, wherever sea-water is present. The
phylum also includes, as one of its large suborders, all the snails
and slugs that are to be found crawling upon the land. These are true
mollusks, which differ essentially from their marine brethren only in
that they breathe by means of a pulmonary sac or lung instead of by
gills. There are also many genera and species of mollusks that find
their habitat only in the fresh water of rivers, lakes, or ponds;
curiously enough, many of these fresh-water forms, like the purely
terrestrial snails and slugs, are air-breathers, possessing no gills
whatever, and are consequently obliged to make periodic visits to
the surface of the water to obtain their necessary supply of oxygen.
There are also numerous forms of mollusks that are entirely deprived
of a shell covering; and, again, there are intermediate types
between these two extremes that produce only more or less developed
rudimentary shells. Notwithstanding these variations in the matter
of a shell covering,—an important consideration in this phylum,—by
reason of their anatomical features these "naked" forms are mollusks
quite as much as are those that secrete the most highly developed
tests.
The marvelous beauty of sea-shells and tropical land-shells,
their almost infinite variety in form and coloring, has given to
them an interest among collectors that is very great. There are
many wonderful conchological collections in public museums and in
private cabinets. It would well repay the lover of beauty as well
as the more serious student of nature to examine carefully such
collections when opportunity offers, for nowhere in the realm of
nature can more exquisite coloring and modeling be found. The fact
that shells may be preserved for all time without the expense and the
vexations of preservative fluids has no doubt induced many [pg307]
to choose this field of natural history for special study. But the
true student of zoölogy does not confine his investigations in this
phylum to considerations of the shell only, for the protective
armor constitutes only a portion, although an important portion, of
the anatomy of the mollusk. On the same principle, it would hardly
suffice to examine only the skeleton of vertebrate animals in order
to become acquainted with the fishes or mammals. In a sense, the
testaceous covering of a mollusk may be likened to an outer skeleton.
The older zoölogists were inclined to ignore almost entirely the
animal or "soft parts" of mollusks, and their classification of
the phylum into "univalve," "bivalve," and "multivalve," based
upon shell-characters alone, has since been proved to be wholly
artificial. The terms "univalve" and "bivalve" are, of course, often
and correctly used to-day to designate mollusks possessing a single
or a double shell, such as the common garden-snail, which carries
upon its back a single spiral shell, and, on the other hand, the
oyster or clam, which is inclosed within two valves which fit closely
together. But these terms are not /technically/ used, although
they do indicate in a general way the more modern classification.
Even among some comparatively recent conchologists a tendency to
belittle the value of the "slimy creature" within the shell has led
to some curious errors of grouping—mistakes which more thorough
and scientific investigation has brought to light. In general, the
higher classification into classes, orders, suborders, and families
is exclusively based upon anatomical features, and to a large extent,
also, is that of the genera; but species are always determined by
their shell or conchological characteristics.
When a certain familiarity with the forms and general appearance of
shells is gained, a glance at the shell alone will almost always
suffice to place it at once in its true generic position, for, along
with modifications of the animal itself, corresponding modifications
of the shell are quite certain to take place. Hence a fairly expert
zoölogist should be able to determine with considerable accuracy from
an empty and dead shell the anatomical features of the animal that at
one time inhabited it. [pg308]
One of the main reasons for the special interest that seems to have
attached to the study of conchology is derived from the fact that the
durability of shells has caused their almost perfect preservation
as fossils from the very earliest periods of geological time, thus
furnishing the key to the solution of many problems of evolution.
Upon this page of the earth's history the letters are sharp and
clear, and geologists possessing a knowledge of recent forms of
mollusks as well as of their geographical distribution have been
enabled to read some wonderful stories of the cosmic history of
islands and continents.
GEOGRAPHICAL DISTRIBUTION
Mollusks are found in every part of the world. The arctic seas
possess their own characteristic faunæ, the more temperate waters of
Europe and of America contain their own peculiar genera and species,
and the warm waters of the tropic seas furnish the conditions
favorable to the life of an immense number of characteristic forms.
Again, there are the littoral species, that live only between
tide-marks and are therefore exposed to the air for a number of
hours each day; some of these live just about high-tide mark and
have become almost terrestrial in their habits, while others must be
sought at the point of lowest tide, where for only a short time each
day they are deprived of their natural element. Then there are the
shallow-water forms, which never appear above low-tide mark save when
a neap tide surprises them; their range in depth extends to about
the hundred-fathom line, more or less. Beyond this depth to several
hundred fathoms other characteristic forms appear, and from the more
profound depths of mid-ocean the dredge has brought to light a host
of curious and interesting species.
It is the temperature of the water rather than the depth that appears
to influence the distribution of marine mollusks. Thus, certain
species whose natural home is in the shallow waters of the Arctic
Ocean have been taken in very deep waters off the southern coast of
the United States, the temperature conditions in both stations being
substantially the same. This fact, however, must not be too freely
accepted as establishing a principle. Some [pg309] shallow-water
forms have been taken at great depths, but in general the abyssal
fauna is a peculiar one that cannot well be marked off into
geographical provinces.
THE ARCTIC PROVINCE
The east coast of America is divided into several molluscan
faunal regions. A series of very-cold-water forms belonging to a
circumpolar region, called the "arctic province," are found as far
south as Newfoundland. On the New England coast a number of these
arctic species are also found, urged south by the influence of the
cold Labrador current. The most characteristic genera belonging to
this arctic fauna which are found upon the Maine and Massachusetts
coasts are /Buccinum/, /Chrysodomus/, /Sipho/, /Trophon/, /Bela/,
/Velutina/, /Trichotropis/, /Lacuna/, /Margarita/, /Pecten/, /Leda/,
/Yoldia/, /Astarte/, and /Mya/. Examples of all these genera are
encountered as far south as Cape Cod.
THE BOREAL PROVINCE
A "boreal province" corresponds with a similar faunal region upon
the European shore. The mollusks which compose this fauna are about
three hundred in number, and range along the New England coast from
the Gulf of St. Lawrence to Cape Cod. It is a somewhat remarkable
fact that many of these species are identical with English and French
forms. The striking genera upon the American side are /Purpura/,
/Littorina/, /Polynices/ (/Lunatia/ and /Neverita/), /Acmæa/,
/Margarita/, /Chiton/, /Doris/, /Æolis/, /Mytilus/, /Modiola/,
/Thracia/, and /Nucula/.
THE TRANSATLANTIC PROVINCE
Cape Cod has been regarded, until very recently, as a sharp
divisional point between the boreal and the transatlantic provinces,
the latter faunal area extending down the Atlantic coast of the
United States to southern Florida. At Cape Cod the Labrador current
is deflected from the coast, and the warmer shore waters south of
that point are unfitted for the development of the boreal forms,
though some of them, as we shall see, have passed the [pg310]
barrier and maintain themselves very successfully at Martha's
Vineyard and in Long Island Sound. Some of the species whose natural
habitat is south of Cape Cod are also to be found north of that
point, but they do not reach their full development in the colder
waters of Massachusetts Bay.
The long stretch of coast-line from Cape Cod to Florida is easily
susceptible of faunal subdivision at Hatteras, below which locality a
decided mixture of Antillean species is apparent. Between Long Island
Sound and Hatteras the littoral molluscan fauna is disappointing
to the collector, for the number of species is relatively small,
and few even of these are entitled to any claims to beauty of
shell. The nature of this coast, virtually a great sweep of exposed
sand-beach, is not conducive to a varied or rich fauna. But if this
portion of the transatlantic province is lacking in interest to
the shell-collector, it is anything but disappointing to the army
of men employed in the oyster- and clam-fishery. It is only within
this faunal area that the American oyster, /Ostrea virginica/, the
best of the edible shell-fish, finds its natural home, and here the
oyster-culture is most extensively carried on.
After storms the Jersey beaches are frequently strewn with /Mactra/,
/Tagelus/, /Arca/, and /Ensis/; in more sheltered places /Fulgur/ and
/Polynices/ (/Lunatia/) are commonly met. These may be accepted as
the most characteristic genera of this province.
Just south of Cape Hatteras an observer is struck with the sudden
change in the appearance of the shells on the beach. /Cardium/,
/Cassis/, /Dolium/, /Arca/, and /Cancellaria/ at once suggest
the West Indies. About the vicinity of Hatteras the Gulf Stream
approaches very near the land, bringing with its warm waters many
wanderers from tropical homes. From Beaufort to Florida there is
another long stretch of exposed and shifting sand-beach, which offers
a scant return to the collector of mollusks.
THE CARIBBEAN PROVINCE
When Florida is reached a new world is opened to the naturalist,
for there a better acquaintance is made with the great Caribbean
province, which, extending from Florida to the northern shores of
South America, embraces all the Bahamas, the West [pg311] Indies,
the Gulf of Mexico, and the coast of Central America. Strangely
enough, the mollusks of the west coast of Florida are more nearly
related to those of the transatlantic province than are the shells
of the east Florida coast. This remarkable fact in geographical
distribution can only be explained by assuming that an open waterway
once existed across the northern part of the Florida peninsula,
connecting the Atlantic and the Gulf, through which a mingling of the
shallow-water forms from Georgia, the Carolinas, West Florida, and
the Gulf coast took place. Thus it would appear that when Florida
was an island the fauna of its east coast, originally largely
Antillean, was less disturbed by the southern migration of American
species. The Florida Keys are essentially Antillean. The Caribbean
or Antillean fauna is an exceedingly rich and varied one. Among the
most prominent genera which may be encountered upon the Florida coast
are /Strombus/, /Fasciolaria/, /Oliva/, /Marginella/, /Natica/,
/Sigaretus/, /Littorina/, /Tectarius/, /Neritina/, /Melongena/,
/Cardium/, /Callista/, /Tellina/, /Lucina/, and /Cyrena/. In such an
extensive and rich faunal province one must not expect to find in any
given locality a representation of all the characteristic genera. For
instance, collections made at Havana, at Nassau, and at Vera Cruz
would each contain forms more or less peculiar and local, but certain
species would be found in each collection.
* * * * *
On the west coast of America quite the same faunal division into more
or less well-marked provinces is to be found. Bering Sea belongs to
the arctic province, and contains, with Labrador and Greenland, many
identical forms.
THE ALEUTIAN PROVINCE
The shore waters from the southern peninsula of Alaska down to about
Vancouver comprise the Aleutian province. Within this area occur
some arctic species, notably the soft-shell clam, /Mya arenaria/,
which the fishermen gather in such large quantities for bait along
the Maine coast. An increasing number of species common to this
west-coast faunal region and to the boreal province of the east coast
are being recorded. Some of [pg312] these have been introduced from
the East by the agency of man, but others no doubt have a natural
range through the icy waters north of America and down through the
Bering Sea into the Pacific.
THE CALIFORNIAN PROVINCE
The Californian province extends from the neighborhood of Vancouver
to Cape St. Lucas and has about five hundred species. The northern
portion of this area contains some very characteristic forms,
together with a good mixture of species of more northern habitat;
it might properly be regarded as a subprovince. From San Diego
south to the cape the character of the fauna gradually changes;
this coast-line of southern California has also been considered a
subregion. The main characteristic of the Californian province is a
large development of /Haliotis/, of the patelliform mollusks, and
of the chitons. A very few minutes on any good collecting-beach
of California would convince the Eastern conchologist that he had
entered upon an entirely new field of research. The most notable
genera are /Calliostoma/, /Chlorostoma/, /Scurria/, /Acmæa/, various
genera of the /Chitonidæ/, /Purpura/, /Monoceras/, /Amphissa/,
/Norrisia/, /Olivella/, /Chorus/, and /Haliotis/.
THE PANAMIC PROVINCE
The warmer waters of the Gulf of California belong to the Panamic
province, which extends down to South America. This is one of the
richest and most interesting faunas in the world. At Panama alone,
Mr. C. B. Adams, a noted collector and student of conchology, took
upward of four hundred species. About eight hundred species are known
in the Gulf of California alone.
* * * * *
It must be borne in mind that these faunal provinces relate to
littoral and shallow-water species, for the present knowledge of
deep-water forms is not sufficient to permit of generalization upon
their distribution.
We review here only the conspicuous forms along our own coasts. It
may be well to note, however, that in some other parts of the world
the development of molluscan life is far [pg313] in excess of
anything to be found upon our shores. The veritable paradise of the
naturalist is the East Indies. There the "aristocratic" genera, so
called on account of their marvelous beauty, occur in their highest
development—/Voluta/, /Mitra/, /Oliva/, /Conus/, and the various
murices. There also are to be found the pearl-oysters, /Meleagrina
margaritifera/, that yield their valuable harvest, and the giant
clam, /Tridacna gigas/, which measures sometimes five feet in
length. Over eight thousand species of mollusks are described from
this surpassingly rich region, yet this vast province, as compared
with the American and European shores, has been but superficially
exploited by the naturalist. In whatever part of the world a
naturalist may find himself, there is always a tempting array of
molluscan life to attract him. Each fauna possesses features peculiar
to itself, and from the point of view of the true naturalist, the
more somber-hued and conventionally formed mollusks of Northern
shores are no less interesting than the gorgeously tinted and
fantastically shaped species of the tropics. From any faunal province
of our own country one may readily gather all forms necessary to
furnish ample material for study from which one may acquire an
excellent idea of the biological features of the entire phylum.
STATION AND HABITS OF THE MOLLUSCA
The word "station" is used to indicate the nature of the surroundings
which an animal chooses as most suited to his well-being. Some groups
of mollusks, like the littorinas, the trochids, the purpuras, and the
majority of those having patelliform shells, generally live on rocks
above low-tide mark; other genera, like /Buccinum/, /Sipho/, and
/Chrysodomus/, prefer rocky or gravelly ground below low-tide mark.
Other mollusks burrow deep in the mud, many prefer sandy bottoms,
while a host of other species seek homes upon the tangled masses of
seaweed, living like arboreal creatures in the submarine forests.
Nearly every conceivable character of sea-bottom or shore-line
between tides harbors its own peculiar types of molluscan life. There
are some very curious genera of bivalves that bore their way into the
hardest rock and [pg314] there find a comfortable shelter for life.
A numerous class of pelagic or free-swimming mollusks supposedly
never go to the bottom at all, but spend the whole of their existence
on or near the surface of the sea, always in open water, where
their fragile shells may not be injured by rough contact with solid
substances.
The food of some is vegetable, of others, animal. The bivalves, like
the clams, oysters, cockles, and mussels, feed only on microscopic
organisms. They create a current of water through their siphons, or
mantle openings, and then, by a process best known to themselves,
catch and swallow all the animalculæ thus brought to their mouths.
The univalves which possess a siphon are, for the most part,
carnivorous, and are often most voracious creatures. They feed upon
any animal matter they can find, while some of them are enabled by
means of a sharply toothed tongue to bore through the solid shells
of other mollusks and extract the succulent vitals from within. One
energetic little mollusk in particular, /Urosalpinx cinerea/, is
for this reason a great pest upon the oyster-beds. Univalves not
possessed of a siphon may generally be considered herbivorous; they
pass most of their time peacefully browsing upon algæ.
Mollusks are all oviparous or ovoviviparous; that is, they lay eggs,
or, laying eggs, they retain them within their shells until the
young are hatched out. As a rule, each species of mollusk has its
own particular method of protecting its eggs from external injury.
Some construct tough, leathery capsules which are strung together in
various patterns. The egg-capsules of /Purpura lapillus/, resembling
little pinkish or yellowish club-shaped stalks, may frequently
be found in the crevices of rocks and under the rockweeds. The
egg-cases of /Polynices/ (/Lunatia/) are most peculiar, resembling
inverted gelatine-bowls with the bottom knocked out; when wet they
are semi-elastic translucent masses in which may be seen myriads of
eggs. /Buccinum undatum/ arranges its hemispherical egg-capsules
in layers one above the other. The number of eggs so deposited is
often very great, running well into the thousands. Egg-capsules of
/Fulgur/ are leathery coils of angular disks adhering by one edge to
a connecting-band of a similar texture. (See Plate I.) [pg315]
In bivalves the eggs are retained within the parent shell until
hatched, and the young, which then escape into the water, are very
different-looking creatures from the parent. Generally the young
bivalve is free-swimming and exceedingly lively in its movements;
sometimes by means of cilia it is enabled to attach itself to any
passing host, and thus the species is widely disseminated. The fry
soon lose their embryonic form and take on the characteristics of the
adult.
The longevity of mollusks varies greatly with the species. Some
attain an age of from ten to fifteen years, while some are only
annuals. Oysters continue to grow for four or five years, after
which they may survive many years more. In truth, little is known
concerning the duration of life even of our better-known shore
species.
In point of intelligence, mollusks must be relegated to a very
low position. They give evidence of possessing no more than
the most primary instincts, those of self-preservation and of
reproduction. There are some forms that exercise a high degree of
protective mimicry. The highest class of mollusks, the /Cephalopoda/
(cuttlefishes, octopi, etc.), is widely separated from the other
classes in the development of faculties that appear to correspond
with intelligence. They are exceedingly crafty in the pursuit of
their prey as well as in eluding capture.
STRUCTURE OF MOLLUSKS
Among the invertebrate animals, especially in the lower orders, wide
physiological departures from central or typical forms are frequent.
It often happens that a whole group or even suborder will differ
so materially in its general characteristics from another group
or suborder belonging to the same phylum that the student will be
puzzled at first to understand how the two can be nearly related. In
many such cases it is only when the essential features of the phylum
are thoroughly understood that the relationships of its suborders
can be appreciated. An example of widely divergent groups within the
same phylum has already been shown in the /Echinodermata/. Who would
at first suppose that the graceful /Astrophyton/ could bear kinship
to the inert [pg316] holothurian, or that both of these have the
closest family ties with the sea-urchins?
The probable reason for these startling departures from a typical
form is that in the lower orders of life, where the organs and their
functions are comparatively simple, the laws of evolution operate
far more quickly in the adaptation of an organism to environment and
changed conditions of life. A decided tendency to this departure from
the type is a feature of the mollusks. It would be difficult, if
not impossible, to give a general description that would fit both a
common garden-snail and the common oyster, yet both are mollusks. A
concise definition of the phylum is therefore practically impossible,
and it seems here as if nature resented all attempts to circumscribe
her living forms by rigid rules.
The most persistent characteristic of the /Mollusca/ is the
possession of the "mantle," a sort of outer skin which, like a bag or
sack, envelops the creature above and about the sides, but is open
below, permitting the animal at will to protrude or withdraw its
foot. From the outer surface of this sheath-like mantle, or fold, a
calcareous shell is secreted. The modifications of this mantle are
infinite; indeed, in some well-marked groups it seems to have wholly
disappeared, having in reality become fused to the sides of the
animal, and having become therefore a mere outer skin, and no longer
a tunic or cloak, as originally intended. As already noted, the
mantle does not always secrete a shell, a fact which again reminds us
that we cannot give a good comprehensive description of the phylum
that always holds true throughout its subdivisions. The best that can
be done is to give in general terms the characters which appear in
a majority of the forms. A convenient method of going about this is
to create, for the sake of clearness, an ideal, model, or fanciful
mollusk and clothe it with all the most salient molluscan features,
and from such a basis to develop, as we go on, the various types of
the actual orders and suborders. There is one class of mollusks,
the /Amphineura/, which conforms reasonably well in most of its
features to our comprehension of the schematic mollusk. This class is
sometimes referred to by biologists as the "primitive" or "original"
mollusks, from which all the other classes have since been derived;
but the [pg317] evolutionary history of the development of the
various molluscan orders through geological time does not seem to
bear out the fact that an "ideal" mollusk, as we shall construct him,
ever actually existed, or that his prototype, the /Amphineura/, was
the first and consequently the ancestral type of the phylum. We must
therefore only accept this ideal mollusk theoretically, to serve as
a guide for the time being. We may profitably use it only as a lay
figure—a sort of manikin, which will introduce us to the phylum.
After our introduction we must forget our imaginary type and abandon
any notion we may have conceived of the parental position of the
/Amphineura/, its closest imitator in actual life.
THE IDEAL MOLLUSK
The ideal mollusk has a compact, somewhat elongated body, the under
or ventral portion of which is thickened into a muscular disk, upon
which it creeps along. This disk is called the /foot/. (Note a snail
thus crawling upon his "foot.") The foot is rounded or obtusely
pointed posteriorly. Forward, the body is slightly narrowed into
a neck, and then expanded again into a head. Upon this head are
carried two projecting, mobile, fleshy tentacles, one upon each
side, that superficially resemble two horns. At the base of each
tentacle, upon the inner side, is an eye. Just below and between the
tentacles is a small horizontal slit,—the mouth,—the lips being
slightly thickened. The visceral portion of the animal is above the
foot, or /dorsal/ to it, and extends the whole length of the animal
from the mouth to the excretory opening, the latter being situated
posteriorly. The visceral cavity is inclosed above by a thin skin;
indeed, it is but the great thickening of this skin below that
constitutes the foot.
[Illustration: Ideal or schematic mollusk.
1, dorsal view: /h/, head; /t/, cephalic tentacle; /sh./, shell
covering visceral mass; /b.m./, outline of body-mass; /r.m.e./,
edge of mantle; /c.t./, ctenidia, or gills; /q.a./, generative
apertures; /r.e./, renal openings; /e.o./, excretory opening; /f/,
posterior portion of foot; /o.e.m./, edge of shell.
2, ventral view: /h/, head; /t/, tentacle; /m/, mouth; /b/, outline
of body; /e.m./, edge of mantle; /s.f./, lower surface of foot;
/c.t./, ctenidia, or gills; /f/, posterior portion of foot.
3, horizontal section, showing heart, nephridia, and gonads:
/m/, mouth; /o/, esophagus; /g/, gonad; /p/, pericardium; /n/,
nephridium, or renal organ; /v/, ventricle; /a/, auricles; /g´/,
gonad aperture; /n´/, renal opening; /e/, excretory opening; /f/,
posterior portion of foot.
4, vertical median section: /m/, mouth; /b.m./, buccal mass; /l/,
liver; /d.a./, digestive tract; /q/, gonad; /f/, foot; /q.o./,
gonad aperture, or opening of oviduct; /r.o./, renal opening;
/e.o./, end of digestive tract, excretory opening; /n/, mantle;
/r/, nephridium, or renal organ; /o.f./, recurved portion of
mantle; /sh./, shell; /v/, ventricle; /p/, pericardium.]
The digestive tract, beginning at the mouth, opens immediately into a
muscular throat, which is called the /buccal mass/. Within the buccal
mass there is a long, fleshy ribbon that bears upon its upper surface
numerous rows of sharp teeth; these rows of teeth run crossways on
the ribbon, each row containing more or less prominent median teeth,
with several laterals upon each side, and with marginal teeth on each
side of the laterals. This is called the /radula/, and is used for
tearing or rasping the food. When [pg319] not in use it lies coiled
up within the buccal mass. Beyond the buccal mass, food passes into
the esophagus, which widens out into a muscular pouch or stomach;
this may also be provided with chitinous teeth or hard knobs or
plates for the purpose of further triturating the food. Above and
partially surrounding the stomach is a large reddish or brownish
liver, which furnishes to the alimentary canal the digestive juices.
From the stomach the intestine leads to the terminal anal opening.
There are two organs, serving the function of kidneys, placed
dorsally one upon each side of the body (/nephridia/). A heart lies
within the median line of the body, and consists of a ventricle and
two lateral auricles. The vascular system is almost entirely closed;
only in so far as it is partially open does it essentially differ
from that of higher groups; the blood is whitish or light bluish,
and receives its oxygenation in the gills or along the free mantle
surface, through which it courses in exceedingly thin capillaries. In
this manner respiration is carried on to some extent throughout the
whole outer surface of the body. There are two /branchiæ/ (gills).
These have the appearance of small feathers and are placed upon
each side of the animal posteriorly; they project slightly. Spread
over the top of this animal, fitting it perfectly, is a thin fleshy
covering attached to its dorsal portion like a skin, but hanging
free, like a flap, over the sides, the head, and the posterior end
of the animal. Upon the sides it may just cover the tips of the
branchiæ, but in front the head is seen to project from under it.
The loose-hanging portion of this sac-like covering is somewhat
thickened, and perhaps recurved upward upon itself. Upon the edge of
this flap all the way around may occur a row of cilia, or tentacular
processes. This cloak-like covering is called the mantle, and, as
already noted, is the most peculiar and persistent characteristic
of the /Mollusca/. The "cavity" formed between the loose-hanging
portion of the mantle and the sides of the foot is called the /mantle
cavity/, and contains posteriorly the gills, or branchiæ. From the
outer surface of this mantle a calcareous secretion takes place,
forming a shell, which, in our ideal mollusk, will be shaped in
conformity with the surface outlines of the mantle, oblong and convex
above. Over the lower portion of the shell the edge of [pg320] the
mantle recurves. When the creature is disturbed or is at complete
rest it may withdraw that portion of the mantle which protrudes from
below the shell entirely within the edge of the shell, so that the
"soft parts" may be wholly covered, and thus protected from harm. In
such a state of rest nothing may be seen from above but a shell. The
entire upper surface of the mantle is firmly attached to the under or
inner side of the shell, except the mantle margin, this being free.
The nervous system consists of a circumesophageal ring of
nerve-cells, with two cords passing along the digestive tract to the
posterior end of the animal. In the head and above the buccal mass
are several series of nerve-ganglia. These also communicate with the
posterior portion of the animal through two parallel cords which pass
along its ventral side. From these four principal branches, which
traverse the entire length of the creature, minor nerve-cords are
thrown off to the tentacles, the foot, the branchiæ, and the various
organs of the viscera. The sexes are separate.
Reviewing our "typical mollusk," we find that it is bilaterally
symmetrical—that is, uniform upon both sides of a median line from
mouth to excretory opening; is unsegmented; has the ventral surface
thickened into a creeping foot or disk; and is possessed of a head
with tentacular processes, a radula, lateral branchiæ, a heart with a
ventricle and two auricles, a well-developed mantle, and a shell.
If the reader can learn these few details of organization he knows
the structure of a mollusk. In turning to the actual living forms he
will find merely modifications (though sometimes confusing ones) of
these various parts.
CLASSIFICATION
The /Mollusca/ are divided into five great classes: /Amphineura/,
/Gasteropoda/, /Scaphopoda/, /Pelecypoda/, and /Cephalopoda/. These
names, it will be noticed, with the exception of the first, all refer
to the /foot/, the modifications of the foot being selected as the
basis of the first great divisions of the phylum. The /Gasteropoda/
crawl upon the thickened ventral surface of their bodies (already
[pg321] referred to as the foot), as the common garden-snail, the
periwinkles, and in general all those mollusks which have a spirally
coiled shell. The /Scaphopoda/ have a long, worm-like foot, with
which they burrow in the sand or mud. Their shells are like miniature
elephant-tusks, but are open at both ends. The /Pelecypoda/ have a
more or less club-shaped foot, utilized, in the many families, for
a great variety of purposes. They are always inclosed in a bivalve
shell. Familiar examples are the oysters, the clams, mussels, etc.
The /Cephalopoda/ have the /foot/ modified into a number of /arms/,
which encircle the head or the mouth. They are the cuttlefishes, the
octopi, squids, etc.
CLASS =AMPHINEURA=
ORDER =POLYPLACOPHORA=
The /Amphineura/, as already observed, approach most closely to the
ideal mollusk just described. They are bilaterally symmetrical.
This fact is so important that it constitutes them a class,
notwithstanding the fact that in respect to the foot (the basis of
division into classes) they would be included with the /Gasteropoda/,
for (barring some exceptional instances) they creep along upon a foot
quite as our ideal mollusk would, and as the /Gasteropoda/ do. The
head carries no tentacles, thus essentially differing in this respect
from the ideal form. The mantle is extended down in front, completely
covering the head. The branchiæ are confined to a few pairs of
/ctenidia/, or plume-like gills, within the mantle groove or cavity,
and are arranged upon each side of the excretory opening like small
feathers.
There are two orders of the /Amphineura/, the /Polyplacophora/ and
the /Aplacophora/ (or /Solenogastres/), the one name meaning "bearing
many plates," and the other "without plates," the word "plate" in
this sense being synonymous with "shell." The shell of the first
order consists of eight calcareous disks arranged in a longitudinal
row along the back or dorsal side of the animal, which overlap like
shingles on a roof and admit of great variation of form in the
various families. [pg322]
It will be observed from the examples given that the shell plates do
not entirely cover the mantle, but that a considerable portion of the
upper mantle surface is left exposed along the side of the animal.
This exposed portion of the mantle is called the /girdle/. It is
always very much thickened and is often exceedingly tough. In some
species it is covered by a great number of calcareous spicules or
granules which are embedded in the leathery mantle tissue. Strangely
enough, the /Chitonidæ/ (a large family of the /Polyplacophora/)
possess a great number of eyes scattered over the shell plates like
minute dots.
[Illustration: /Chiton spinosus/, dorsal view.]
The members of this order are to be found in all parts of the world,
but their greatest development is upon the west coast of America.
In California the student of marine life has a splendid opportunity
to examine the chitons. They are generally to be found adhering
to the under surface of stones about low-tide mark. They are very
sluggish in their movements and may readily be removed from their
resting-places by suddenly thrusting a knife-blade under the foot
and prying them off. When thus detached they have a habit of rolling
up into a ball and so remaining indefinitely; to prevent this they
should be placed at once in a jar of sea-water, where they will
resume their natural position. For preservation as cabinet specimens,
chitons should be tied down between two boards or flat substances,
to hold them firmly extended until dried; otherwise they are apt to
contract out of shape.
[Illustration:/Chiton/, ventral view: /an/, anus; /cten/, ctenidia;
/ft/, foot; /mant/, mantle-edge; /mo/, mouth.]
Six or eight species are exceedingly common upon the west [pg323]
coast. The collector who has successfully taken a number of these
will not fail to note the varying degrees of width of the girdle in
the different species. In some cases the girdle partially covers the
overlapping shell plates. The largest of all the chitons inhabits
the California shores and is known as ^Cryptochiton stelleri^.
It measures fully six inches in length and three in width. In
/Cryptochiton/ the girdle is continued over the shell plates as a
tough, gritty, brownish covering. The shell plates are white, and,
as detached pieces, are frequently to be found cast up upon the
California beaches, where, from their curious shape, they are often
referred to as "butterfly-shells."
[Illustration: /Chiton ruber./ /Chiton apiculatus./]
On the east coast of America there are comparatively few species, and
these are all small and inconspicuous. The three commonest ones are
^Chiton ruber^, ^C. albus^, and ^C. apiculatus^. They may readily be
found on stones or dead shells fished up from below low-tide mark, or
in rock-pools left by the receding tide.
ORDER =APLACOPHORA=
This second order of the /Amphineura/ is entirely destitute of the
shell plates characteristic of the first. The outer mantle surface,
however, develops a number of calcareous granules which correspond to
a shell. The /Aplacophora/ are symmetrical, having the mouth and the
excretory opening at the anterior and posterior ends respectively.
The foot is greatly modified, being narrowed at times to a mere slit
along the ventral surface. Some of them have long, worm-like bodies.
This is no doubt a very primitive form of mollusk, or, if not a
primitive form, it has greatly degenerated from some higher type.
They are supposed to be commensal in habit and live in the deeper
water offshore.
The /Aplacophora/ are not littoral animals, and it is extremely
unlikely that one will ever encounter them upon the beach, unless,
possibly, after the severest of storms. We may therefore leave them
with this mere mention and proceed to the second class of mollusks,
the /Gasteropoda/. [pg324]
TABLE SHOWING THE CLASSIFICATION OF THE GASTEROPODS AND SCAPHOPODS
DESCRIBED IN THIS CHAPTER
Phylum =MOLLUSCA=
Class =GASTEROPODA=
Order =OPISTHOBRANCHIATA=
Suborder =TECTIBRANCHIATA=
Families Genera Species
BULLIDÆ ^Bulla^ ^B. (Haminea) solitaria^
^B. occidentalis^
^B. nebulosa^
APLYSIIDÆ ^Aplysia^ ^A. Wilcoxii^
Suborder =NUDIBRANCHIATA=
DENDRONOTIDÆ ^Dendronotus^ ^D. arborescens^
ÆOLIDIDÆ ^Æolis^ ^Æ. papillosa^
DORIDIDÆ ^Doris^ ^D. bilamellata^
Order =PROSOBRANCHIATA=
Suborder =DIATOCARDIA=
Families Genera Species
ACMÆIDÆ ^Acmæa^ ^A. testudinalis^
^A. testudinalis,^
Var. ^alveus^
^A. mitra^
^A. patina^
^Lottia^ ^L. gigantea^
FISSURELLIDÆ ^Fissurella^ ^F. alternata^
^F. barbadensis^
^F. (Glyphis) aspersa^
^Lucapina^ ^L. crenulata^
HALIOTIDÆ ^Haliotis^ ^H. splendens^
^H. rufescens^
^H. cracherodii^
TROCHIDÆ ^Margarita^ ^M. cinerea^
^M. helicina^
^M. undulata^
^Calliostoma^ ^C. occidentale^
^C. jujubinum^
^C. annulatum^
^C. canaliculatum^
^C. costatum^
^Chlorostoma^ ^C. funebrale^
^C. brunneum^
^Trochiscus^ ^T. norrisi^
^Livona^ ^L. pica^
TURBINIDÆ ^Turbo^ ^T. castaneus^
Var. ^crenulatus^
NERITIDÆ ^Nerita^ ^N. peleronta^
^N. tessellata^
^N. versicolor^
^Neritina^ ^N. reclivata^
^N. viridis^
Suborder =MONOTOCARDIA=
JANTHINIDÆ ^Janthina^ ^J. fragilis^
SCALIDÆ ^Scala^ ^S. lineata^
^S. multistriata^
^S. groenlandica^
^S. angulata^
NATICIDÆ ^Polynices^ ^P. (Lunatia) heros^
^P. (Lunatia) triseriata^
^P. (Lunatia) lewisii^
^P. (Neverita) duplicata^
^P. (Neverita) recluziana^
^Natica^ ^N. clausa^
^N. canrena^
^Sigaretus^ ^S. perspectivus^
CAPULIDÆ ^Crepidula^ ^C. fornicata^
^C. plana^
^C. aculeata^
^Crucibulum^ ^C. striatum^
^C. spinosum^
LITTORINIDÆ ^Littorina^ ^L. litorea^
^L. rudis^
^L. palliata^
^L. irrorata^
^L. angulifera^
^L. scutulata^
^L. planaxis^
^Lacuna^ ^L. vincta^
^Tectarius^ ^T. muricatus^
^T. nodulosus^
CERITHIIDÆ ^Cerithium^ ^C. floridanum^
^C. muscarum^
^C. minimum^
^Bittium^ ^B. nigrum^
^Cerithidea^ ^C. scalariformis^
^C. sacrata^
VERMETIDÆ ^Vermicularia^ ^V. spirata^
STROMBIDÆ ^Strombus^ ^S. pugilis^
^S. gigas^
CYPRÆIDÆ ^Cypræa^ ^C. exanthema^
^C. spurca^
^C. spadacea^
^Trivia^ ^T. pediculus^
^T. quadripunctata^
^T. californica^
^T. solandri^
DOLIIDÆ ^Dolium^ ^D. galea^
^D. perdix^
^Pyrula^ ^P. papyratia^
CASSIDIDÆ ^Cassis^ ^C. tuberosa^
^C. cameo^
^C. testiculus^
^C. inflata^
Families Genera Species
MURICIDÆ Subfamily Muricinæ
^Murex^ ^M. rufus^
^M. pomum^
^Trophon^ ^T. clathratus^
^Urosalpinx^ ^U. cinerea^
^Eupleura^ ^E. caudata^
^Pteronotus^ ^P. festivus^
^Ocinebra^ ^O. poulsoni^
^O. lurida^
^O. interfossa^
^Cerostoma^ ^C. nuttallii^
^C. foliatum^
MURICIDÆ Subfamily Purpurinæ
^Purpura^ ^P. lapillus^
^P. patula^
^P. hæmastoma^
^P. crispata^
^P. lima^
^P. saxicola^
^Monoceras^ ^M. lapilloides^
^M. engonatum^
^Chorus^ ^C. belcheri^
COLUMBELLIDÆ ^Columbella^ ^C. mercatoria^
^C. (Anachis) avara^
^C. similis^
^C. (Astyris) lunata^
^C. (Amphissa) corrugata^
^C. (Astyris) gausapata^
NASSIDÆ ^Nassa^ ^N. trivittata^
^N. obsoleta^
^N. vibex^
^N. fossata^
^N. perpinguis^
^N. tegula^
^N. mendica^
BUCCINIDÆ ^Buccinum^ ^B. undatum^
^Chrysodomus^ ^C. decemcostatus^
^Sipho^ ^S. Stimpsoni^
^S. pygmæus^
^Siphonalia^ ^S. kellettii^
^Tritonidea^ ^T. tincta^
TURBINELLIDÆ ^Fulgur^ ^F. carica^
^F. canaliculata^
^F. perversa^
^F. pyrum^
^Melongena^ ^M. corona^
FASCIOLARIIDÆ ^Fasciolaria^ ^F. gigantea^
^F. tulipa^
^F. distans^
VOLUTIDÆ ^Voluta^ ^V. junonia^
MARGINELLIDÆ ^Marginella^ ^M. apicina^
OLIVIDÆ ^Oliva^ ^O. literata^
^O. mutica^
^Olivella^ ^O. biplicata^
^O. boetica^
CONIDÆ ^Conus^ ^C. floridanus^
^C. pealii^
CANCELLARIIDÆ ^Cancellaria^ ^C. reticulata^
Class =SCAPHOPODA=
DENTALIDÆ ^Dentalium^ ^D. dentale^
^D. pretiosum^
^D. hexagonum^
^Entalis^ ^E. striolata^
[pg328]
CLASS =GASTEROPODA=
The class /Gasteropoda/ is the largest and most comprehensive
subdivision of the /Mollusca/, and within its wide range of families
many differing details of organization are to be found. As a class it
possesses all the most characteristic features of the phylum, though
it is frequently modified in a high degree. This class includes
all the univalve mollusks (except /Nautilus/ and /Dentalia/), such
as the snails, the whelks, and the host of spirally coiled land,
fresh-water, and marine shells.
The gasteropod foot is, as has been remarked, primarily the same
as in our schematic mollusk—a flat, muscular disk caused by
the thickening of the ventral body-surface. The neck, head, and
tentacles are also quite the same, but considerable modification
of these organs will be found when we come to examine some
specimens. The mantle is always present, except in the nudibranch
or non-shell-bearing forms; but in few of the /Gasteropoda/ is the
mantle so regularly simple as in our ideal mollusk.
Perhaps the most striking feature of the /Gasteropoda/, and
one that will at first surprise him who has in mind the simple
structure of the ideal mollusk, is the fact that they are always
asymmetrical—that is to say, a median line drawn longitudinally
through a gasteropod will not divide it into halves of similar
anatomical structure.
The quality of symmetry is an important one throughout the lower
orders of animal life. In nearly all phyletic or class descriptions
the word "symmetry" occurs, and its exact meaning must be understood.
Take, for example, a human being; a median line drawn vertically
would divide him into two similar halves—upon each side would be
an eye, an arm, a leg, etc., of similar shape and construction. So
far at least as the external features [pg329] go, man is then a
symmetrical creature; likewise the vertebrates in general. Cases
of actual symmetry are found in the lobsters and crabs and in the
segmented worms. It is usual in describing mollusks broadly and in
general terms to call them symmetrical animals, yet here is the
largest class within the phylum, whose representatives are none of
them symmetrical. In the /Gasteropoda/ the mouth is anteriorly placed
in the head, just as in the ideal form, but the digestive tract,
after traversing the visceral cavity in the usual fashion, suddenly
turns forward and terminates in an excretory opening either on the
right or on the left side of the animal, just back of the head. The
various other orifices for the genital and renal glands are also
placed in this unexpected anterior position. The gills, or branchiæ,
are to be found upon one side only, forward of the heart, and
differ somewhat in appearance from the plume-like processes of the
/Amphineura/.
What, then, has become of the corresponding gill we should expect to
find on the other side? The symmetrical shape of the foot is not in
the least altered, but what has happened to cause this distortion of
the visceral portion of the animal? And, finally, will this torsion
of the body of the snail perhaps account for the spiral nature of the
shell?
An evolutionary process is supposed to have taken place in mollusks,
which, if real, would no doubt account for these curious conditions
of torsion in the /Gasteropoda/; but the theory upon which this
process is based is altogether speculative, and is not fully
sustained by the facts in the case. Originally all mollusks are
presumed to have been symmetrical, and are assumed to have resembled
very much in form the schematic creature we have already described.
Now, for some reason, certain of the primitive mollusks, but not all
of them, began to develop a larger visceral mass, which, continuing
to enlarge throughout many generations, began finally to protrude
above and form a hump on the dorsal side of the animal. This hump,
containing the liver, a portion of the intestines, and the generative
glands, as it increased in bulk became so much elevated that it could
no longer maintain itself in an erect position over the body, but,
impelled by its own [pg330] weight, began to sag over to one side.
Such a process would of course tend to twist the digestive tract and
bring the excretory opening constantly farther forward on one side.
At the same time, this process would necessarily interfere, by the
weight of the overhanging viscera and the shell covering the mass,
with the development of the branchiæ lying upon that side and now
crowded under the visceral mass. Thus, according to this theory, this
process has continued until, in the modern gasteropod, the digestive
tract has been bent upon itself and twisted from a straight course
into a curve of almost 180°, bringing the excretory opening near or
just over the head, where it empties into the mantle cavity; while
the original right gill, by the same movement, has been brought to a
position on the /left/ side of the head, forward of the heart, the
original left gill having been crowded out, eventually to atrophy and
disappear. The same torsion is found in the nerve-cords; the heart,
situated at about the pivotal position of this twisting process,
has turned about upon itself, leaving an auricle in front of the
ventricle, one auricle, like one of the gills, having been lost. The
mantle portion covering the visceral hump naturally continued to
secrete its shell, though always in conformity with the change, the
result being the familiar spiral form of the usual gasteropod shell.
This theory may not be satisfactory, but the asymmetry of gasteropods
is a problem to be solved, and a more interesting line of biological
investigation could not be found.
Let us now take a good example of a gasteropod and locate its various
organs; at the same time we may use the occasion to refer to more
important modifications of these organs which will be encountered
later in the various genera. The most available gasteropod on the
east coast of the United States for this purpose, is /Fulgur/, both
on account of its large size and its abundance. /Buccinum/ may be
used if the student is north of Cape Cod and therefore unable to
secure a good living specimen of /Fulgur/; the anatomical differences
between the two are slight.
Note the siphon protruding forward from a notch in the shell. This
consists merely in an elongation of a fold of the mantle, which is
held in a manner to constitute a tube, through which [pg331] the
animal draws in water to supply the gills, lying just back of the
siphon and concealed under the mantle in the cavity already spoken
of as the mantle cavity. With the exception of that portion of the
mantle which constitutes the siphon, no part of its margin, it will
be observed, can be seen, the edge of the shell completely hiding it
from view.
In some genera the siphon is exceedingly long—in fact, longer than
the body of the animal. In these cases the mollusk is generally fond
of burying itself in the sand and maintaining communication with
the world above only by means of this long, fleshy tube. In some
genera the siphon is protected by an elongation of the shell, as in
/Fasciolaria/ (Plate LXXVI). An extreme example of this is given in
the figure on page 343, which represents a species of /Murex/, where
the siphon is not only protected by the shell, but the shell itself
is further protected by the double row of sharp spines with which it
is beset.
[Illustration: /Buccinum undatum/: /si/, siphon.]
There are some genera which possess no siphons at all, in all of
which cases there is no notch in the shell opening, the aperture
being round, as in /Natica/ and in /Littorina/ (pages 368, 371). The
mollusks of this type make a fold in the forward part of the mantle
which serves as a siphon. Such a muscular folding in the mantle would
be technically called a /functional siphon/.
On the posterior dorsal side of the foot is attached a horny plate,
of concentric structure about a central or subcentral point or
nucleus. This is called the /operculum/, and serves to close the
entrance of the shell when the animal is withdrawn, the object no
doubt being protective. The opercula vary to a great extent in the
different genera; in some cases they are calcareous, in others
cartilaginous. When the aperture of the shell is very large it often
happens that the operculum does not entirely close the opening, as
in /Fulgur/, but in /Buccinum/ it is a close fit. The operculum is
entirely wanting in the /Pulmonata/, one of the [pg332] large orders
of the /Gasteropoda/. The figures represent some of the commoner
types of opercula.
[Illustration: Various forms of opercula. /Turbo/ (/Sarmaticus/).
/Turbo/ (/Callopoma/). /Livona./ /Ampullaria./ /Natica./ ]
The opercula have been utilized a great deal in the classification
of the /Gasteropoda/, and especially in some groups that have become
terrestrial in habit. Often, when shell-characters utterly fail to
give a clue to the proper generic position of a new or rare mollusk,
the operculum may be relied upon to indicate it.
[Illustration: Various forms of opercula. /Pyrula./ /Purpura./
/Littorina./ /Aulopoma./ /Torinia./ /Neritopsis./ /Strombus./
/Conus./]
TENTACLES
Two tentacles project like fleshy horns from the sides of the head.
These are not retractile, as in the land-snails, and their office
appears to be that of sensory organs. In both /Fulgur/ and /Buccinum/
the tentacles are comparatively short and stout, and have expanded
bases; in many other genera they are long and slender. Almost without
exception the /Gasteropoda/ possess tentacles. [pg333]
EYES
In /Fulgur/ the eyes are situated near the bases and upon the outer
sides of the tentacles; in /Buccinum/ they are extremely small and
are mounted about midway between the bases and the tips of the
tentacles. This is the usual position for the eyes in the marine
/Gasteropoda/. Only in the pulmonates, or land-snails, are the eyes
placed at the summit of the tentacles. Sight does not appear to be
a very important sense in the gasteropods, although the eye in some
instances becomes a highly developed organ. A number of forms that
have the habit of burrowing deep into the sand or mud are quite
destitute of visual organs, and certain cave-dwelling land-shells
have entirely lost the sense of vision.
MOUTH AND PROBOSCIS
The mouth will easily be seen in both /Fulgur/ and /Buccinum/. It is
a small slit with slightly thickened, fleshy lips, and is placed on
the lower forward portion of the head. In the case of both of these
genera the mouth is situated at the end of a proboscis. It will be
noted that /Fulgur/ has a comparatively long and stout proboscis, or
snout, which is not retractile. /Buccinum/ has a smaller one. It is
fairly safe to assume that all gasteropods that possess a proboscis
are carnivorous. This organ is greatly developed in some genera,
where it actually exceeds in length the rest of the animal. In such
instances, no doubt, the creature is enabled to reach the interior
portions of the shells of its victims and to devour every vestige
of their flesh, for the mouth is most conveniently placed just at
the end of this long, trunk-like organ. The genera which have no
proboscis are, almost without exception, vegetable feeders.
We must now remove the animal from its shell. It is well to boil
it first, for this does away with the annoying mucous secretion
that is freely exuded by glands in the foot when the creature is
roughly handled. Alcoholic specimens are apt to be much contracted
and hardened, and are therefore less satisfactory as subjects for
anatomical study. If it is not convenient to boil the [pg334]
specimen, break away the shell with a hammer, using care not to
lacerate the soft, fleshy portion within; when this is accomplished,
wash the animal carefully to remove the slimy exudation. Note the
"visceral hump," which is spiral, and which formerly occupied the
upper-whorl portion of the shell. The thin skin covering it is the
mantle, which below is greatly thickened and free, lying about the
foot like a heavy fleshy flap.
MANTLE
The mantle-edge in both of these examples is simple; that is to say,
it possesses no fringe of tentacles, nor is it supplemented by extra
processes, characters which mark many genera of marine /Gasteropoda/.
In /Fulgur/ and /Buccinum/ the mantle-edge does not protrude below
the edge of the shell; but in many genera, especially those which
possess smooth, glossy shells, like the cowries (/Cypræa/) and the
graceful /Oliva/, the mantle is proportionately very much larger. In
these two genera, when the animal is extended, as in crawling about
the sand, the mantle curves upward and incloses a large portion of
the shell itself. Indeed, in some genera the shell is almost entirely
concealed by this extension of the mantle (/Sigaretus/, /Natica/,
etc.).
When the shell is removed, the folding of the mantle which
constitutes the siphon can be plainly seen. The office of the siphon
has already been referred to, also the fact that the presence of a
siphon in the gasteropod mollusk may always be determined by merely
glancing at the shell alone, for a notch at the base of the aperture
indicates the place through which the siphon passed. In /Buccinum/
this is merely a notch, but in /Fulgur/ the siphonal canal of the
shell is much longer. Just why the long siphons of some mollusks
should be naked and exposed to danger, while others are so carefully
protected by elongated, portions of the shell, is a mystery, but
nature is full of such contradictions.
THE GASTEROPOD FOOT
The foot is long, broad, and flat on the under side, like a disk.
The variations in the gasteropod foot are almost infinite. [pg335]
In some of the species it is amazingly large and powerful, as
in /Polynices/ (/Natica/), and in most of the forms which live
along sandy beaches. These are sometimes provided in front with a
wedge-shaped process called the /propodium/, which serves admirably
as a plow to push aside the heavy wet sand through which the animal
forces its way. In /Nassa/, which is so common all along our coasts,
the foot has two terminal appendages or points behind.
[Illustration: /Sigaretus lœvigatus/, showing excessive
development of the propodium (/pr./) and metapodium (/met./) in a
mollusk living in sand (the shell, which covers only the liver and
adjacent parts, has been removed): /l/, liver; /s. ap./, aperture of
proboscis, here deflected from the median line; /t/, /t/, tentacles;
/f/, foot.]
[Illustration: /Oliva textilina/ showing how the front part of the
foot (/f/) is developed into a sort of fender, the propodium (/pr./):
/e/, /e/, eyes; /m. ap./, front appendage of mantle; /m. ap.´/,
hinder appendage of mantle, folded into the suture when the animal is
at rest; /si./, siphon; /t/, /t/, tentacles.]
There is no single feature of mollusks more important than the foot,
for upon the many modifications of this organ the various molluscan
classes are founded. The name /Gasteropoda/ means "stomach-foot,"
the latter organ being merely a thickening of [pg336] the ventral
surface of the animal, giving to the creature, when active, the
appearance of crawling upon its stomach.
If a living gasteropod is placed in a jar of sea-water and left
undisturbed it will soon crawl up the side of the glass and thus
afford an excellent view of the extended under surface of its foot.
The majority of the gasteropods are lethargic and slow in movement,
but others will be found to be exceedingly lively and able to creep
up the sides of the jar and make their escape in a surprisingly short
time. Further modifications of the foot will be mentioned later.
THE MANTLE CAVITY
Now let us place the animal with the foot below and the head facing
us. The spiral visceral hump will point back and away from the
observer. The mantle covering the visceral portion is thin and
translucent like an ordinary skin, but at the base of the visceral
mass the mantle suddenly thickens very greatly, and spreads over
the dorsal portion of the foot or the body like a cloak. The space
between the body and the loose-lying mantle is called the /mantle
cavity/, and within this area are to be found several important
external organs. To find these it is well to cut the mantle flap in
a straight line, beginning just back of the head and ending at the
point where the mantle is attached to the body. This will most easily
be done with scissors. Having thus divided the mantle in front, throw
back the two flaps. On the right-hand side (left of the animal), and
attached to the inner side of the mantle thus exposed, will be seen
the branchiæ, or gills.
THE BRANCHIÆ, OR GILLS
They consist of a row of flattened filaments bound together at the
base like the leaves of a book. The blood is conveyed to these
gills by a large vein, and is then forced through the thinly walled
filaments, being thus brought into close contact with the water, to
which it releases its carbon dioxide, and from which it receives the
life-giving oxygen. In certain gasteropods there are two sets of
gills, one placed upon each side of the body [pg338] (as in the
ideal mollusk); but the presence of two sets of gills only indicates,
in these gasteropods, that the twisting process of the viscera,
already alluded to as so remarkable a feature of this class, has not
proceeded far enough to destroy the functional activity of one of the
gills.
[Illustration: Anatomy of the internal organs of a female gasteropod,
viewed from the dorsal side. The roof of the mantle cavity has been
divided by a longitudinal incision and the flaps laid out, that on
the left bearing the ctenidium and osphradium, and that on the right
the rectum and terminal part of the oviduct. The muscular dorsal wall
of the body and the introvert have been divided so as to bring into
view the anterior part of the alimentary canal and a portion of the
nervous system. The buccal cavity has been tilted up and opened so
as to show the odontophore, and the esophagus has been cut through
near the anterior end. A portion of the ventral wall of the crop
has been removed so as to bring the internal folds into view, and
the interior of the nephridium with the contained portion of the
intestine has been exposed. The stomach is not seen, being hidden by
the nephridium, and the ovary is not represented. /an./, anus; /ant.
aort./, anterior aorta; /aur./, auricle; /buc./, buccal cavity; /cer.
buc. con./, cerebro-buccal connective; /cer. g./, cerebral ganglia;
/crop/, crop; /cten./, ctenidium; /int./, intestine; /jaw/, jaw;
/l. buc. g./, left buccal ganglion; /l. sal. gl./, left salivary
gland; /neph./, nephridium; /neph. ap./, nephridial aperture; /od./,
odontophore; /oes./, esophagus; /oes'./, anterior end of same, cut
and turned aside; /osph./, osphradium; /ovid./, oviduct; /ovid'./,
terminal thick-walled portion of oviduct; /pleur. g./, pleural
ganglion; /post. aort./, posterior aorta; /post. oes./, posterior
esophagus; /rad. s./, radula sac; /r. sal. gl./, right salivary
gland; /rect./, rectum; /sal. du./, salivary duct; /siph./, siphon;
/supra. g./, supra-esophageal visceral ganglion; /tent./, tentacle;
/vent./, ventricle.]
In general, it may be said that the breathing process of mollusks
does not markedly differ from the respiratory methods of higher
forms of animals. Whether the breathing is effected by gills or by
a pulmonary sac, the essential features of the system are the same
as in fishes or mammals. There are, however, some rather peculiar
developments in the breathing system of gasteropods that are worthy
of notice. The gills themselves differ throughout the various orders
of this class both as to their structure and their relative position;
in one of the orders (the /Pulmonata/) the gills have entirely
disappeared, and are replaced by a pulmonary sac which fulfils the
purpose of a lung.
It is a generally accepted theory that all land or air-breathing
mollusks were originally marine, but by a gradual change in their
habits have developed into terrestrial forms, losing their gills
and acquiring in their place organs which correspond to lungs. The
theory is supported by the fact that many species of marine mollusks
live between tide-marks, and for several hours daily are obliged to
maintain life outside of their native element. The /Littorinidæ/,
which may always be found in abundance on both the east and the west
American coasts, usually live high above low-tide line, and some
tropical species of this genus actually live in the trees above
the reach of high tide. They have gills just as in /Buccinum/ or
/Fulgur/, but the /Littorina/ shell is strongly suggestive of certain
land forms, and there is reason to believe that the genus is in
course of evolution into a pulmonate. On the other hand, there are to
be found in fresh water numerous genera which are true pulmonates,
and which are obliged to come to the surface every few minutes to
obtain air. One notable genus of marine gasteropods possesses both
lungs and gills, and one marine form has entirely lost its gills
and breathes only by means of lungs. It is quite likely that all
mollusks are able to breathe more or less all along the exposed
mantle surface, which is usually [pg339] crowded with capillaries
with exceedingly thin walls. This very remarkable method of surface
respiration is proved to exist in the nudibranch or shell-less marine
/Gasteropoda/, for they possess neither gills nor lungs.
OSPHRADIUM
Lying just under the gills, and side by side with them, is a smaller,
plume-like organ having the appearance of a smaller gill; it is
called the /osphradium/. The office of this organ is not definitely
known, but the supposition is that it is the seat of the olfactory
nerves. The osphradia are not always present, but whenever found they
are placed in close conjunction with the gills, in order, probably,
that the animal may best determine the quality of the water brought
by the siphon to the breathing-organs. In /Buccinum/ the osphradium
is especially prominent. In all mollusks the sense of smell is highly
developed. A dead animal anchored to the bottom will very soon
attract the carnivorous /Mollusca/ from every direction. This is not
a bad way to trap certain species that live upon rocky stations and
are otherwise difficult to secure by the dredge.
On the left-hand side (right of the animal), and adhering to the
under side of the mantle flap, which has been thrown back, a somewhat
inflated and convoluted tube, the rectum, will be seen. It terminates
in an opening just within the mantle-edge. By the side of this are
the renal and genital openings.
* * * * *
Having now examined the external organs, we may investigate the
internal anatomy of our subject. To do this thoroughly requires
considerable skill, but for the purpose of merely discovering the
relative positions of the principal internal organs a little care
only is necessary. The work will be greatly facilitated by boiling
the animal for a few minutes, for this serves to harden the tissues
and to separate the various organs in a most satisfactory manner.
To begin, open the proboscis from the mouth, cutting back so as to
expose the esophagus. It will be seen that the throat is long and
very muscular. [pg340]
RADULA
Hidden among the red stripes of muscular fiber which line the inner
surface of the throat will be found a fleshy strip covered upon
one side with many transverse rows of chitinous teeth. This is the
/lingual ribbon/, or /radula/. Remove as much of it as possible, and
examine it with a hand-glass. The radula is a most important organ,
and is a unique possession of /Mollusca/, except the pelecypods, or
bivalves. Usually it lies coiled up like a spiral when not in use;
its purpose is to tear and rasp food.
[Illustration: Three rows of teeth from the radula of /Fasciolaria
trapezium/.]
[Illustration: Portion of the radula of /Imbricaria marmorata/.]
The radula has been the subject of much study by conchologists, and
has furnished the basis for an arrangement of the numerous sections
of gasteropods into somewhat well-defined groups. If the observer has
a strong glass he will notice that each transverse row of teeth on
the ribbon consists of a median or central tooth with several points
or "cusps." /Fulgur/ has a median tooth with three cusps; /Buccinum/
one with six. On each side of the median tooth is a lateral tooth,
which in /Fulgur/ will be seen to have six cusps, and in /Buccinum/
five. In many patterns of radulæ there is, besides the median and
lateral teeth, still another paired row, called the marginals. In
the accompanying figures are given some examples which show small
sections of lingual ribbons. While all the radulæ of mollusks are
capable of being grouped by their general characteristics, yet in no
two species of mollusks are the radulæ quite identical. [pg341]
VITAL ORGANS, STOMACH, LIVER, RENAL GLANDS, ETC.
The digestive tract will be found to widen out a short distance back
into a crop or stomach, and, continuing still further, to lose itself
in a soft, brownish mass within the coiled spire, which is the liver.
The very large size of the liver leads one to suspect that /Fulgur/
and /Buccinum/ must be voracious creatures to need so large an organ
for the secretion of bile. In many species of mollusks the stomach
and intestines are filled quite solidly, at times, with a gelatinous
transparent substance called the /crystalline stylet/. Just why the
digestive tract should be clogged with this substance no one has
yet been able to explain, so here again is a chance for original
investigation. The intestine curves about after reaching the liver,
and comes forward again to appear once more as the rectum, clinging
to the inner surface of the free portion of the mantle.
Closely associated with the liver, but differing slightly in color,
is the gonad, or organ in which the genital products are formed.
Situated dorsally and forward of the liver and gonad is a large renal
gland, which may readily be detected by its peculiar structure. In
some forms the kidney is closely associated with the gonad, and seems
to coöperate with the latter in the generative functions.
HEART AND VASCULAR SYSTEM
To find the heart, make an incision into the body just at the
posterior end of the gills. The heart is white and round, and
is inclosed within a cavity known as the /pericardium/; it has
a ventricle and one or two auricles, although in /Buccinum/ and
/Fulgur/ there is but one auricle.
There is nothing remarkable about the vascular system to distinguish
it from that of many higher forms of animals. It is, however, not
completely closed—by which is meant that the blood is not always
contained within arteries or veins, and that it does sometimes flow
into other organs and floods certain other body-cavities, although
the vascular system of mollusks is by no means so completely open as
is that of insects and crustaceans. [pg342]
Having examined the animal which inhabits the shell and gained an
idea of its anatomy, we may now turn to an inspection of the house
which it has built for itself, and here we shall find a delightful
subject for study.
THE GASTEROPOD SHELL
An industrious hour of collecting upon almost any beach will provide
the student with an abundance of interesting shells. Putting aside
the bivalves, the univalve or gasteropod shells remaining should be
closely examined for the purpose of becoming acquainted with their
various conchological features. The collector will see at once that
he has a number of species that differ more or less widely in their
general form, size, texture, and sculpture. Some shells will be long
in proportion to their width, with many turns of the spire which
probably terminates in a sharply pointed apex; others will be almost
round, with comparatively few spiral turns which end in a blunt apex,
giving to the specimen outlines suggestive of a dome. A wide range of
characters will be found in the mouths or apertures of the shells,
some being almost if not quite round, others oblong and with a notch
cut into the lower portion of the opening, and others possibly with
this notch extended into a sort of semi-inclosed channel. A first
lesson in classification of the /Mollusca/ may be taken by dividing
the results of the first day's collecting of univalve shells into
groups according to these prominent shell-characters.
[Illustration: Parts of a gasteropod shell: /a/, anterior canal; /b/,
body-whorl; /c/, columella; /l/, outer lip; /m/, mouth or aperture;
/p/, posterior canal; /s/, sutures; /sp/, spire; /u/, umbilicus.]
A good knowledge of the parts of a gasteropod shell is essential to
the student, and it can readily be acquired. Four specimens are given
in the accompanying figures, representing highly divergent [pg343]
types of marine gasteropods, and their respective characteristics may
be noted by comparing them one with another: /Fasciolaria tulipa/
(Plate LXXVI.), a Floridian shell; /Polynices heros/, a common
species found on all the sandy shores of the American Atlantic
coast; /Murex tenuispina/, an Indo-Pacific species much prized by
collectors; and /Acmæa testudinalis/, commonly found in Maine and
Massachusetts at low tide clinging to rocks.
[Illustration: /Polynices heros/; /Acmæa testudinalis/, from below;
/Acmæa testudinalis/, profile; /Murex tenuispina/.]
The extreme top of the shell is called the /apex/, and it may be
either sharply pointed or obtuse. Each turn is called a /whorl/; the
last one, and always the largest, is called the /body-whorl/, the
others collectively forming the /spire/ of the shell. When the animal
first emerges from the egg it is always provided with one or two
whorls, which generally may be distinguished at the apex as smoother
than the rest of the spire, and a faint line may be discovered where
the shell began its growth after birth. These [pg344] first whorls
of embryonic growth are usually referred to as the /nepionic whorls/.
The interstices between the successive whorls are called /sutures/,
and these lines of juncture may be shallow or deep according to the
convexity of the whorls. The sculpturing of the whorls is often
of great complexity, and exhibits /nodules/, /varices/, /ribs/,
/revolving striæ/, /spinous processes/, and /lines of growth/.
It frequently happens that there is a complete absence of any
sculpturing whatever, the whole surface of the shell being perfectly
smooth, save for the faint lines of growth to be detected only under
a magnifying-glass. The outer edge of the mouth or aperture of the
shell is called the /outer lip/. This may be more or less thickened,
expanded, or simple. The inner lip is called the /columella/, and may
be greatly extended anteriorly. When the mouth of the shell is round,
and there is no notch or indentation either above or below, it is
said to be /continuous/.
The /anterior canal/ is for the accommodation of the siphon of the
animal, which, as noted above, may be very long or almost entirely
absent; therefore the character of the shell generally indicates
whether or not the animal itself possesses a long siphon. There is in
some forms a notch at the upper extremity of the mouth, which is for
the accommodation of the anal discharges. When present it is called
the /posterior canal/.
It will be noted that all the specimens figured as examples, save
one, are spiral, the coils revolving about an imaginary axis. When
the whorls are not too closely coiled there is left open to the view
a hollow space throughout the entire length of the shell, which is
called the /umbilicus/. When the coils of the shell are very compact
there is no umbilicus to be seen. The umbilical opening may be very
large, giving a clear view of the inner surfaces of all the whorls
right through to the apex. The usual gasteropod shell is in reality a
hollow tube wound about an imaginary axis. Since the tube increases
in size as it progresses, the base of the shell is necessarily
wider and larger than the apex. Thus all gasteropod shells may be
reduced in shape to the single type of a cone or top, modified by
the excessive length or shortness of the spire, or otherwise altered
by special peculiarities. In /Polynices duplicata/ (page 368), it
will be observed that while the [pg345] umbilicus is fairly large,
its external opening, in the adult shell, has been almost completely
closed by a callous process thrown off from the inner or columellar
lip.
Gasteropod shells may be /sinistral/ or /dextral/, according as
the whorls turn to the left or right. The great majority of marine
species are dextral, having the opening on the right, although a
few species exhibit the curious property of being constructed upon
either the one or the other plan without apparent reason. Sinistral
specimens of many normally dextral species have been discovered, but
they are so rare as to warrant the belief that such specimens are
merely deformities or monstrosities resulting from some accident of
birth.
The collector will soon learn to distinguish between young and adult
specimens, for those finishing touches of wonder and beauty which
the mollusk gives to his protective covering are made only by the
adult. The outer lip of young gasteropod shells is usually thin and
fragile; even if slightly thickened, it has an unformed or unfinished
appearance.
Shells differ greatly in their /structure/, many species being
porcelanous like china, others glassy, and many more are of a softer
chalky composition. In the latter case the shell is usually covered
with a thick membranous skin, which, when removed, leaves a dull,
lusterless, white body beneath. Shells of this texture, when cast
upon the beach, soon yield to the weathering action of sun and air.
The porcelanous shells are composed of successive layers of carbonate
of lime, throughout which is a filmy membranous framework of a
substance similar to that of which the covering of the /Crustacea/ is
formed. The mode of deposition of the various layers of crystalline
calcic carbonate and the peculiar lineation of their outer surfaces
give rise to the iridescent or nacreous appearance of some shells.
With the exception of those species in which the mantle of the
animal is extended over the edge of the aperture and more or less
envelops the entire test, there is an outer skin of membranous or
organic matter which overlies the surface of the shell. This skin
is sometimes quite thick, often hairy, and is usually of a dull
greenish- or brownish-yellow color. In many genera this [pg346]
outer covering of the shell is excessively thin. In old specimens
the epidermis is usually worn away from the apical whorls. It often
happens that the shells of the most exquisite colors and markings are
thus rendered somber and unattractive by their tenants during life;
when the animal dies, or when such specimens are kept in a cabinet
for a period of time, the epidermis dries, cracks, and falls off,
revealing the wealth of color and design beneath.
The growth of the gasteropod shell is accomplished by the exudation
from the margin of the animal's mantle of a liquid containing the
shelly matter in solution. The mantle-edge is provided with a
complicated system of glands and pores, from which is secreted this
"stony liquor." This more or less viscous liquid, containing the
carbonate of lime and the other inorganic materials of which the
shell is composed, hardens upon exposure, and the shelly matter is
then deposited in crystalline form around the edges or lip of the
shell aperture. The gasteropod shell therefore grows by the continual
building out of its aperture through successive depositions of shelly
matter at the extreme edge of the lip. At the extreme edge of the
mantle margin are situated those glands which secrete the materials
for the epidermis of the shell, and as one would therefore expect,
this outermost layer of epidermis is first produced in the advancing
growth of the shell. There also are situated the pigment-glands,
which produce the color-secretions. The various layers of the shelly
substance are successively deposited inside the mouth of the shell by
glands situated just back of the extreme edge of the mantle margin.
Thus in the growth stage, if one could examine closely the aperture
of a gasteropod shell, one would observe at the extreme tip of the
lip this projecting epidermis, just beneath it and just inside the
aperture a thin deposit of shelly matter, just beneath this, and
farther in, another layer, and still farther in a third layer.
The growth of nearly all gasteropod shells is marked by periods of
rest. During the inactive seasons the creature may thicken the edge
of the aperture to a greater or less extent by an extra deposit of
shelly matter, for otherwise the thin lip might soon be [pg347]
injured or broken. These places where the lip was thickened, as a
temporary protection until the young animal decided to continue
building, appear on the surface of adult shells, and persist as
/varices/, "raised lines of growth," "longitudinal ribs," etc. Such
forms of sculptural markings generally occur at equidistant points
and preserve a scheme of regularity which would indicate that the
periods of rest were of seasonal occurrence. All irregularities and
all surface features of the external shell simply reflect certain
peculiarities of the mantle margin of the animal; all spinous
processes, for instance, as in the marvelous /Murex tenuispina/,
indicate the existence of finger-like processes extending from the
mantle margin, which once occupied the hollow thorns projecting
from the shell. When the outer surface of a shell is devoid of
any sculpturing and is perfectly smooth, one may assume that the
mantle margin of the animal was simple. If the edge of the lip has
a crenulated appearance and the surface of the whorls is decorated
with revolving ribs, the mantle margin was probably folded or wavy.
There can be no doubt but that the entire mantle surface is provided
to some extent with glands for the secretion of shelly matter, for
if any portion of the shell is accidentally injured the animal soon
repairs the break with a calcareous deposit. But such repairs are
never homogeneous in texture with the other parts of the shell of
normal growth; the patches are never covered externally with an
epidermis, and they are always devoid of color. The function of the
epidermis is to protect the calcareous shell from the corroding
agents contained in sea-water. Hence it is that, when the epidermis
is removed, "dead shells" exposed to the influence of the water
or the weather soon lose their brilliancy and luster, and become
undesirable for specimens either for the cabinet or for study. It
often happens that living shells, inhabiting a region where, for one
cause or another, the water is highly charged with impurities of an
acid nature, are discovered to be badly corroded about the apex,
where the epidermis is thin and likely to be rubbed off. For this
reason specimens collected in harbors near large cities or near the
mouths of rivers are apt to be poor and defective.
The inner surface of all shells, if not actually nacreous, is
[pg348] always perfectly smooth. When foreign substances, such as
grains of sand, enter the shell and cannot be removed by the animal,
the irritation caused thereby to the soft, fleshy creature induces
discharges of a liquid from the glandular surface of the mantle,
which hardens about the offending substance and glazes it over with a
smooth, pearly deposit.
/Acmæa testudinalis/ (page 343) presents a special type of gasteropod
shell which is found in several families. Here the spire seems to
be wholly absent, and the entire shell consists of but one large
body-whorl. There are very many of these patelliform species,
inhabiting many seas and belonging to many different genera, and
in nearly all cases their embryonic shells display a spiral form.
After birth the animal does not build his house upon the spiral
plan, but expands the shell into one large shield-like covering.
The student, however, must not presume that /Acmæa/ is an ancestral
type just because the simple character of the shell is suggestive
of the model chosen to represent a schematic mollusk; anatomically
/Acmæa/ presents the complications of body-torsion which show a very
considerable evolutionary change, and indicate that its simple shell
is probably a degenerate form of a once more highly developed and
convoluted one.
The forms, the architecture, and the painting of gasteropod shells
are so infinite in variety that it would be unwise to attempt a
description of their marvels. A close observer of nature's works
soon becomes prepared for every surprise, but he never ceases to be
charmed and fascinated by his new discoveries. The careful student
alone can learn really to see and appreciate the wonders of nature,
and this is especially true in the study of the /Mollusca/.
CLASSIFICATION OF GASTEROPODS
The /Gasteropoda/ far exceed all the other divisions of the
/Mollusca/ in the number of their genera and species. Apparently
this has not always been the case. There is evidence tending to show
that in past geological epochs the pelecypods (the bivalve shells)
outnumbered the gasteropods, but that in the course of time the
increase in the genera of gasteropods has been more [pg349] rapid.
To judge also from the very large number of extinct families among
the cephalopods, which once flourished in astonishing abundance, it
would appear that they are a dying race.
The classification of the /Gasteropoda/ is primarily a division into
three great orders: the /Opisthobranchiata/, the /Prosobranchiata/,
and the /Pulmonata/. The /Pulmonata/, which include the land and
fresh-water gasteropod shells, are characterized by the presence of
a breathing-sac, or lung, instead of gills. They are, therefore,
essentially air-breathers, and would perish if kept too long under
water. The /Opisthobranchiata/ and /Prosobranchiata/ are marine,
and, like all animals which breathe by means of gills, soon die
when removed from the water. We have already noted, however, how
some genera of marine gasteropods that find their station about
high-tide mark are able to live for considerable periods out of the
water, notwithstanding the fact that they are fully equipped with
gills and not possessed of lungs. Indeed, there is one large family
of prosobranchs (the /Cyclostomatidæ/) that has become entirely
terrestrial in habit, its members having lost their gills and
acquired lungs, but their organization otherwise is so essentially
that of the prosobranchs that they have never been considered as
pulmonates.
The main difference between these two orders of marine gasteropods
is that in the prosobranchs the breathing-organs (the gills) are
placed in a position forward of the heart, and the degree of torsion
(page 330) characteristic of this molluscan class has been continued
until the auricle of the heart is in front of the ventricle. There
is always a shell, usually spiral, and, with few exceptions, an
operculum. In the opisthobranchs, on the other hand, the relative
position of the heart and gills is reversed, and they further differ
from the prosobranchs in that the sexes are always united in each
individual. The opisthobranchs are not always provided with a shell.
One division of the order, known as the "nudibranchs," are entirely
naked. These are commonly called the "sea-slugs," and are to be
found crawling about the marine vegetation in shallow water, in
tide-pools, and on the piling of old docks. Curiously enough, the
sea-slugs (see page 354) have no gills at all, but, having lost these
apparently essential organs, are [pg350] enabled to "breathe water"
through their skin. They are wonderfully beautiful creatures, and the
collector must not fail to secure some specimens, put them into a jar
of sea-water, and watch them expand.
There are other more superficial differences between the prosobranchs
and the opisthobranchs, which will enable even a beginner to
distinguish them at a glance. When the latter are possessed of an
external shell, it is bulbous, generally glassy, and with a simple
lip, the aperture extending the entire length of the shell. Again,
the mantle or the propodium of the foot is greatly extended and
usually covers the shell almost wholly.
With the exception of the nudibranchs, which are common all along
the Atlantic shore, especially north of Cape Cod, there are very few
opisthobranchs to be found in American waters. Their shells are not
very abundantly found anywhere, though in Florida there are two or
three species which an untrained collector might discover.
Practically all the gasteropod or univalve shells that will be taken
by the ordinarily expert collector along the shore are prosobranchs.
This order includes the great majority of marine gasteropods, and
is entitled to the distinction of claiming, in the great number of
its genera and species, the most startling eccentricities of form
and color to be found among the /Mollusca/, if not among all marine
invertebrates.
Only those species which are actually abundant on the Atlantic and
Pacific shores of the United States, and which are likely to be found
by the untrained collector, are selected from the long list of forms
which belong to the three faunal regions involved.
ORDER =OPISTHOBRANCHIATA=
SUBORDER ~TECTIBRANCHIATA~
To avoid confusion, it is well to keep the systematic table in view:
Class Orders Suborders
=GASTEROPODA= =OPISTHOBRANCHIATA= =TECTIBRANCHIATA=
=NUDIBRANCHIATA=
=PROSOBRANCHIATA=
=PULMONATA=
[Illustration: PLATE LXV. Bulla occidentalis, enlarged. Bulla
nebulosa. Lottia gigantea, inside view. Fissurella alternata.]
As has already been remarked, shell-bearing opisthobranchs are not
abundantly represented in number of species in North American waters.
South of Cape Cod, in muddy bays and well-sheltered places, the
little shell, /Haminea solitaria/, may, however, often be found in
considerable numbers.
GENUS ^Haminea^
^H. solitaria.^ Like all external opisthobranch tests, the shell of
this species is thin and fragile, and would appear to be of small
importance to the creature it only partially protects. It is devoid
of spire, is shining bluish-white, sometimes brownish in color,
and is marked with revolving grooves, which, being cut across by
irregular growth-lines, give its surface a faintly decussated
appearance. The aperture is as long as the shell; the columella is
incurved. This little species is especially abundant in shallow
water about Vineyard Sound and in Peconic Bay.
[Illustration: /Haminea solitaria./]
GENUS ^Bulla^
^B. occidentalis.^ This species, which is found in the waters
of Florida on all sandy beaches, is a relative of the Northern
species just described. The shell is larger than that of /Haminea
solitaria/, and has a color-pattern of mottled or clouded
reddish-brown on a white foundation. There is no spire; there
is a pit in place of an apex; and the aperture extends the full
length of the shell. To the naked eye the surface appears smooth
and shining. It is an exceedingly variable species, occurring all
through the West Indies, but not north of Florida. The shores of
the keys along the west coast of Florida are often strewn with
these shells after storms. The animal, like all the shell-bearing
opisthobranchs, is very large as compared with the shell, and the
large mantle folds recurve upward, almost completely hiding the
shell from view. (Plate LXV.)
^B. nebulosa.^ This is one of the largest and finest species of
the family /Bullidæ/. It is found on the coast of California south
of San Francisco. The shell is much larger than that of either of
the Atlantic species mentioned above, but very closely resembles
them in outline, although it is built upon a more generous plan
and is more richly painted. It is brownish, mottled with white and
yellow patches, and is very suggestive of certain kinds of birds'
eggs. The animals have a greatly extended mantle which almost
completely envelops the shell. The foot is extremely large, with
great wing-like developments upon each side, called parapodia. Some
species of /Bulla/ have been seen to swim by means of the lazy
flapping of the parapodia. (Plate LXV.)
SEA-HARES
Closely allied to these outer-shell-bearing opisthobranchs is a large
and important group of tectibranchs, known as [pg351] "sea-hares."
They have a mantle so greatly developed that it actually covers the
shell, and its edges unite and fuse over the top. The shell, in
consequence, having almost ceased to be of use as a protection, has
degenerated into a mere horny plate, and has lost all resemblance to
the ordinary gasteropod shell. Having practically lost its protective
office and become a mere internal plate, it is quite probable that
it will in time wholly disappear. The gills of the sea-hares are
concealed under a flap of the mantle, their position being posterior
to the heart. The most conspicuous representative of this type of
tectibranchs in the United States is the following:
GENUS ^Aplysia^
^A. Wilcoxii.^ This species appears at times in vast numbers in
the waters of Florida, until the sea may truly be said to be
fairly alive with them. They swim lazily with a waving motion of
the parapodia. They disappear as mysteriously as they come, and
for months not a specimen will be seen. There is a variety of this
Floridian /Aplysia/ which occurs at Cape May, but no sea-hares are
to be found north of that point. The tropical Pacific furnishes an
astonishing wealth of these creatures, belonging to many genera
and species, and among them are some of the most beautiful of the
invertebrate animals.
SUBORDER ~NUDIBRANCHIATA~
The opisthobranchs are divided into two suborders, the second of
which is called /Nudibranchiata/. The name is well chosen and
very suggestive, for it means "naked or exposed gills"; but this
anatomical feature is only one of the peculiarities of this suborder.
The nudibranchs are commonly known as "sea-slugs"; for, like the
land-slugs, which are also true mollusks, they possess no shell at
all. That they at one time carried a shell is evident from the fact
that they are born with a rudimentary testaceous covering, which soon
afterward disappears.
A striking peculiarity of the nudibranchs is that the conventional
molluscan mantle is not usually apparent. Instead of seeing the usual
flaps or folds of the mantle which more or less encircle mollusks,
and which one seems to have a right to expect, [pg352] they are
entirely absent, and the body of the sea-slug assumes in consequence
a worm-like appearance. Other notable features of the nudibranchs
are the great number of tentacular processes that usually project
from the dorsal region of the animal, and, in many of the genera, an
entire absence of gills. When the gills are present, as is the case
in several of the nudibranch families, they are not placed along the
side of the animal, where one would naturally look for them, but are
arranged in the form of a rosette of plume-like processes situated in
the posterior dorsal region, or, in other words, on the animal's back.
Nudibranchs are commonly to be found all along the Atlantic and
Pacific coasts of North America, and more especially in the colder
waters north of Cape Cod. They are essentially littoral, and live
upon algæ in shallow water, upon eel-grass in sheltered places,
and in tide-pools, where there is more or less vegetation. They
crawl about the fronds of algæ, or swim, foot upward, with a gentle
and undulating motion, or, when caught between tides, may be seen
clinging to the under surface of rocks. Protective resemblances
have been so remarkably developed in the nudibranchs that they are
not always easy to discover; indeed, one may actually be looking at
one for some time without suspecting it to be other than some torn
fragment of seaweed.
* * * * *
There are many species belonging to several genera which frequent
the Maine and Massachusetts coasts, but those most likely to be
encountered are the following:
GENUS ^Dendronotus^
^D. arborescens.^ This species is about one inch long and variable
in color, but is usually reddish-brown or rose. There are no
tentacles, but in their place are two antler-like appendages
pointing forward and branched like a tree. All along the back are
two rows of these curiously branched processes, which give to
the animal the appearance of a plant. These /cerata/, or dorsal
papillæ, are delicately transparent, contractile, and richly
colored. The function of these papillæ is not fully known. As
the animal has no specialized breathing-organs, it is reasonable
to suppose that respiration is carried on through the outer skin
and perhaps all over the surface of these branched papillæ. The
liver, which [pg354] in most nudibranchs is extremely large and
completely surrounds the stomach, in /Dendronotus/ also extends
into these dorsal cerata, so that they may have some sort of
digestive function.
[Illustration: /Dendronotus arborescens./]
GENUS ^Æolis^
^Æ. papillosa.^ This is probably the commonest nudibranch upon
the North Atlantic coast, and it occurs as frequently in European
waters. It may readily be found clinging to stones, algæ, the
piling of wharves, eel-grass, etc., in bays or in rocky tide-pools.
The color is yellowish-gray to orange, with purplish or olive
spots. The cerata are very numerous, and cover the dorsal portion
of the animal save for an open space along the middle of the back.
There are two sets of tentacles, the two dorsal and the two simple
labial tentacles. The foot tapers behind to a sharp point, and is
truncate in front. As in /Dendronotus/, the liver is diffused into
the cerata, which in /Æolis/ are simple tubular processes without
the branching character of those of the former. Both species lay
their eggs in a gelatinous, bobbin-like cord, which is hung in
festoons over rocks or upon zoöphytes, or at times they wind the
cord in a coil upon the surfaces of stones. When the young first
hatch out, they are provided with a glassy nautiloid shell, a fact
which would indicate that at some remote period they were, like
most mollusks, provided with a shell. /Æolis/ swims in an inverted
position, and is at times exceedingly active. It is very variable
in coloring and in the number of cerata.
[Illustration: /Æolis papillosa./]
GENUS ^Doris^
^D. bilamellata.^ In /Doris/ we find a quite different type of
nudibranch from that presented by the two genera /Dendronotus/
and /Æolis/. In one there were numerous branched cerata or dorsal
papillæ, in the other many plain cerata, and in neither case were
there any specialized [pg355] breathing-organs. In /Doris/,
however, there are no dorsal papillæ at all, the back being covered
with calcareous spicules, which form a sort of secondary shell.
There is a circlet, or rosette, of retractile plume-like gills, or
branchiæ, placed in the middle of the back posteriorly. There are
various species of /Doris/, and of closely allied genera belonging
to the family /Dorididæ/, which are to be found along the New
England coast in tide-pools and among rocks. Those seen by the
writer never appeared to be other than very sluggish creatures, and
proved to be rather unsatisfactory tenants of the aquarium.
[Illustration: /Doris bilamellata./]
When discovered at low tide upon moist seaweed or stones, or when
disturbed in the water, nudibranchs often appear like small lumps of
jelly-like tissue, without a single attractive feature. It is only
when they are placed in a jar of sea-water and left unmolested for
a few moments that they unfold their beauties to the view. On the
Pacific coast there are numerous species of nudibranchs, occupying
corresponding shore stations and exhibiting the same degree of high
coloration. There are over a thousand species of sea-slugs scattered
about the various seas. They find their greatest development in
tropical waters, and for brilliancy of tint and variation in form
are unequaled by any other class of animal life, save perhaps the
butterflies.
ORDER =PROSOBRANCHIATA=
To this exceedingly large and comprehensive order of gasteropods
belong the great majority of univalve mollusks. In point of number of
genera and species and in abundance of individuals, the prosobranchs
probably exceed all the other orders of mollusks combined. They may
be called the typical gasteropods, the shell being univalvular and
generally spiral, and the animal exhibiting the singular torsion
of the visceral mass which has placed the breathing-organs forward
of the heart. They are provided with an operculum (placed upon the
posterior dorsal portion of the foot), which is used to close the
aperture of the shell against [pg356] enemies when the animal
retires within its fortress. They are all marine except a very
few families, which, supposedly of marine derivation, have become
terrestrial in habit.
The prosobranchs are further subdivided into suborders according to
certain peculiarities of the heart and breathing-organs. There is
a group of these prosobranchs which gives evidence of an inferior
degree of that visceral torsion which is always found in the
gasteropods. In this group, or suborder, the heart has two auricles,
and there is a pair of gills instead of only a single one. Other
internal organs are paired just as they were represented to be in
the schematic mollusk. This group also seems to show its primitive
character in the want of a proboscis and a siphon, or, in some
families, by having the ventricle of the heart traversed by the
intestinal canal, just as in the lower class of mollusks, which
includes the clams and oysters. For the most part the shells of this
group are not typically spiral, but are patelliform, shield-like
coverings, with only a suggestion of a spiral form at the very tip
of the apex. This group of primitive prosobranchs is included in the
following suborder:
SUBORDER ~DIATOCARDIA~
This suborder is named from the presence of two auricles in the heart.
FAMILY ~ACMÆIDÆ~
The first family to be noted is the /Acmæidæ/. Its principal genus,
/Acmæa/, is well represented on both the east and the west coast of
the United States.
GENUS ^Acmæa^
^A. testudinalis.^ This species is found in vast numbers all along
the New England shore, clinging to the rocks between tides. They
are usually called limpets. The shell is solid, conical, with an
oval outline, and with no trace of a spiral form in the adult. When
the shell is thoroughly cleaned, it generally presents a mottled
coloration of pale green, brown, and white. Inside it is white
and nacreous, with a large brown [pg357] area under the apex.
The animal has a powerful foot, by means of which it is enabled
to cling to a rock with great strength. In order to dislodge it,
it is necessary to approach carefully, and, taking the creature
unawares, quickly slip a broad knife-blade under the foot,
otherwise it is quite impossible to tear it from its resting-place.
/A. testudinalis/ lives entirely between tides, and ranges from the
northernmost waters to New York. It feeds upon algæ and is a very
sluggish animal. It has been said to leave its resting-place and
wander about in search of food, returning to its original and usual
spot when the tide begins to ebb. (Page 343.)
^A. testudinalis,^ variety ^alveus.^ This variety is smaller, more
fragile, and oblong. It lives upon eel-grass, its oblong shell
being adapted to the narrow leaves of the grass. The coloration is
brighter—reddish-brown spots on a white surface. It is exceedingly
common on the New England coast.
[Illustration: /Acmæa testudinalis/, var. /alveus./]
^A. mitra.^ On the Pacific coast there are a number of acmæas. /A.
mitra/ is often found dead upon the beaches. It is conical in form
and pure creamy-white in color. It looks very much like a clown's
pointed cap.
^A. patina.^ This is also very abundant in California. Outside it
is dark in color and is often incrusted with mineral deposits.
Within there is a dark ring around the edge, then a zone of
bluish-white, and a patch of brown just beneath the apex.
GENUS ^Lottia^
^L. gigantea.^ This is the largest of the California limpets.
Specimens three inches long have been found. The outer surface
of the shell is rough and brownish in color. The apex is near
one end. Within it is almost black, shining, lustrous, with a
horseshoe-shaped muscle-scar under the apex. The color is bluish
and brown. (Plate LXV.)
FAMILY ~FISSURELLIDÆ~
This is an extensive family, including several genera and a number
of species, commonly known as keyhole-limpets. In the general form
of the shell they closely resemble the true limpets, the /Acmæidæ/,
except that they have a hole, or rather a slit, in the shell just
back of the apex. Often this slit is so long that it has entirely
removed the apex of the conical shell.
GENUS ^Fissurella^
^F. alternata^, ^F. barbadensis^. These species occur upon the
southern shores of the United States, the latter, however, being
confined to [pg358] extreme southern Florida. /F. barbadensis/
has heavy longitudinal ribs and is light green within, with a rosy
circle about the apical perforation. (Plate LXV.)
GENUS ^Glyphis^
^G. aspersa.^ One of the numerous species belonging to this family
which are found on the west coast of the United States. It is about
one and a half inches long, grayish-white, with sharply raised
longitudinal ridges, slightly rayed, crossed by revolving ribs,
which give to the outer surface a decussated appearance. The apex
is forward of the center, and is entirely replaced by a round
perforation. The edge is wrinkled, and within smooth and white.
GENUS ^Lucapina^
^L. crenulata.^ The largest of the keyhole-limpets; the shell
is often four inches in length, while the animal, with its huge
yellowish foot and dark-colored mantle, which is thrown back,
almost concealing the shell upon its back, is much larger. The
apical perforation is very large. Shell flattened, with radiating,
rounded, crowded ribs; brownish-white in color; edge crenulated;
within pure white. It is found at Monterey, but live specimens are
not very frequently seen near the beach. (Plate LXVI.)
FAMILY ~HALIOTIDÆ~
GENUS ^Haliotis^
This family is closely allied to the /Fissurellidæ/. The species are
known on the Pacific coast by the name of abalone shells, and in
England and the Channel Islands as ormers or sea-ears. There are no
species of /Haliotis/ on the east coast of the United States, but
one has recently been dredged at a considerable depth in West Indian
waters. This family, with the last, possesses the striking anatomical
feature of having the heart traversed by the digestive tract. It
also has two gills, the degree of torsion in the visceral mass not
being sufficient to have crowded out and destroyed the original
right gill. The shell is spiral, but is so greatly flattened, and
the body-whorl is so greatly extended, that the shell quite loses
the spiral appearance. Along the dorsal side of the shell is a row
of holes, through which project numerous tentacular processes from
the mantle. The outer surface of the shell, before it is polished,
is usually rough and unattractive, but within, when the [pg359]
animal is removed, it displays a most beautiful and highly colored
nacreous surface. The spot near the center of the inner shell
surface where the muscles of the foot were attached is usually
most brilliantly colored. The shell of the abalone is susceptible
of taking a very high degree of polish, and is extensively used in
commerce for colored mother-of-pearl and for inlaid work. /Haliotis/
is a vegetable-feeding genus. They cling with great tenacity to rocks
about low tide, and it requires skill to remove them without breaking
the shell. There are several species in California. The Chinese use
the abalone for food, and have waged a persistent war upon the family
along the Pacific coast until the specimens are not nearly as common
as formerly. They are also eaten in France and in Japan.
^H. splendens.^ The largest and perhaps the most attractive in
appearance of the Californian species. Speaking of this beautiful
shell, Professor Keep says: "Within, a whole rainbow is condensed
in one of the magnificent shells, though the shades of green are
most conspicuous. The coloring in the center is particularly fine,
resembling a peacock's tail. There are about six open holes near
one side of the shell, and its length is about the same number of
inches." (Plate LXVI.)
^H. rufescens.^ A large abalone, which sometimes attains a length
of eight or nine inches. It is red in color, with three open holes
in the body-whorl. The outer portion of the shell is usually
incrusted with mineral deposit and overgrown with vegetation.
^H. cracherodii.^ Very dark green without, with five to nine holes;
length from one to six inches; spire exceedingly short. Common on
the Californian coast in crevices of rocks at low tide.
FAMILY ~TROCHIDÆ~
This is one of the largest and most interesting families of the
/Mollusca/. It contains many apparently widely separated genera
and a host of species, which for the most part are littoral, the
majority actually living between tide-marks. The typical trochid
shell is top-shaped or pyramidal, having a broad base and many
closely wound flat whorls terminating in a sharp apex. All the
trochids are nacreous within the aperture—a character which is
constant throughout the family. The animal has but one gill (the
left), a short snout, and often frontal lobes on the head. The
edge of the mantle or the epipodial line of the foot is usually
ornamented with from three to five cirri. The tentacles are [pg360]
long and slender, with short peduncles for the eyes; the operculum
is corneous, with a central nucleus. The animals are herbivorous,
feeding upon algæ. The trochids are essentially tropical shells, and
the most of the genera which are comprised in the family are only to
be encountered in the warm waters of the Pacific and Indian oceans.
Some forms are very beautiful, and frequently are used as mantel
ornaments, and the shells of one little species, which is opalescent
in its coloring, are still extensively gathered in the East Indies,
to be polished and strung like pearls in necklaces.
GENUS ^Margarita^
On the Atlantic coast north of Cape Cod the trochids are represented
by the genus /Margarita/, with five or six species. The shells are
small, thin, and globosely depressed, with smooth or transversely
striated whorls. The aperture is nearly circular, with a simple lip.
[Illustration: /Margarita cinerea./]
^M. cinerea.^ This species has several prominent revolving ridges
upon the upper side of the whorls, with finer ones on the base.
Very fine growth-lines cover the entire shell. It ranges all along
the coast north of Cape Cod, but is not usually found between
tides. The writer has dredged many specimens in shallow water at
Eastport and Bar Harbor.
[Illustration: /Margarita helicina./]
^M. helicina.^ A thinner and more globose species than the last,
with a translucent, shining, smooth surface of a yellowish or olive
color. /M. helicina/ is very fond of the leaves of /Laminaria/, and
is often found clinging to them when storms have torn these great
algæ from the bottom and cast them upon the shore. At Bar Harbor
they are common upon the eel-grass in Rodicks Weir. This species
can generally be distinguished by its iridescent, metallic luster.
[Illustration: /Margarita undulata./]
^M. undulata.^ A commoner species, perhaps, than either of the
preceding, sometimes found on the rocks of sheltered coves at
exceptionally low tides. Judging from the number often to be found
in the stomachs of fishes, they must be considered excellent food
by the cod and its allied species which thrive along the Maine
coast. No doubt millions of /M. undulata/ are yearly destroyed
in this way. The shell is depressed, with four rounded whorls, a
flattish base, and a large umbilical opening. In color it varies
from rose-red to brown. The surface is decorated with numerous
revolving raised lines placed at uniform distances. Just below
the suture the body-whorl is somewhat undulated with short folds.
Height three tenths of an inch, base four tenths of an inch.
[pg361]
GENUS ^Calliostoma^
This genus is better represented on the Pacific coast of the United
States than upon the Atlantic. It comprises a series of marvelously
beautiful shells, often exquisitely colored. They are regularly
conical or pyramidal in shape, with flattened bases. One never tires
in the search for calliostomas. They are not common enough to cause
one to lose interest, and whenever a good specimen is captured it
seems as though one had found some gem cut and polished by nature's
skilful hand and prepared for a place of honor in the cabinet.
^C. occidentale.^ The only species of this genus found on the
northeast coast. It is larger than /Margarita cinerea/, but
somewhat resembles it. It is shining nacreous within and without,
and has strong revolving ribs, the upper one on each whorl often
being broken into a circular row of white dots. The lip is
crenulated. This very pretty species is not likely to be met with
upon the shore, but may be dredged in shallow water on gravelly
bottoms along the Maine coast. Height about one half of an inch.
[Illustration: /Calliostoma occidentale./]
^C. jujubinum.^ A species which occurs in the waters of Florida.
Its form is almost that of a true pyramid. The sutures can scarcely
be distinguished. The shell is marked by brown and purplish-red
spots on a white background, and has numerous revolving ribs broken
into rows of white dots like little glazed beads. The umbilicus
is funnel-shaped and wide. In Tampa Bay this shell is frequently
found on sponges, and may sometimes be gathered on the beach after
storms, even as far north as Hatteras. There are as many as twenty
species of this genus in American Atlantic waters, but they are
either rare or have deep-water stations.
^C. annulatum.^ A remarkable species of /Calliostoma/, found in
California. The whorls are adorned with revolving rows of raised
dots, and the sutures are frescoed in exquisite purple. This
beautiful species lives upon seaweed, and on pleasant days comes
to the surface of the water. It can then be collected from a boat
by drawing in quantities of seaweed. It is very unlikely that the
collector will ever find a specimen upon the beach, for the shell
is too fragile to withstand the rough handling of the waves. Length
one inch.
^C. canaliculatum.^ The largest member of this genus to be found
in American waters. It resembles the last species in form, but
lacks the purple sutures. The revolving ribs are very numerous and
prominent. There is no umbilicus. Length one to one and a half
inches. Found on the Pacific coast.
^C. costatum.^ A heavier shell than the preceding, with somewhat
more rounded whorls. Reddish-brown in color; numerous revolving
ridges; no umbilicus; about three quarters of an inch in length. It
is found in rocky places, and sometimes in considerable numbers,
just at low-tide mark. Found in California. [pg362]
GENUS ^Chlorostoma^
This genus is represented in California by several species, the
commonest of which is probably /C. funebrale/—a doleful name, no
doubt given on account of the jet-black color.
^C. funebrale.^ The shell is thick and strong, like most
between-tide species, which are constantly exposed to the buffeting
of the waves. It is to be found in countless thousands upon rocks
exposed at low tide, and may be gathered at any time except full
flood-tide, like the littorinas and purpuras of the east coast.
Within the aperture the surface is nacreous and greenish in tint;
the last whorl is drawn in, like gathers, at the suture. The
umbilicus is closed. There is a white nodule at the base of the lip
of the columella. Length one half of an inch to one inch. (Plate
LXVII.)
^C. brunneum.^ This species is brown, as its name would indicate,
and there is greenish nacre within the aperture. It lives upon
kelp, or upon rocks at very low tide. Length about an inch. (Plate
LXVI.)
GENUS ^Trochiscus^
^T. norrisi.^ A flattened shell with rounded, dome-like spire and
obtuse apex; a fairly common species. It has a wide, deep umbilicus
and a sharp lip. It is of a rich brown color, with dark chestnut
about the umbilical region and greenish-white within the umbilicus;
there is a band of dark olive-green about the inner margin of the
lip. The shell is about two inches in diameter and of a somewhat
greater height. The operculum is multispiral, with a central
nucleus, and is shaggy and rough. Like all other trochids, it feeds
upon algæ. It is often found upon the beach after violent storms.
Found in California, south of San Francisco. (Plate LXVI.)
GENUS ^Livona^
^L. pica.^ This large and interesting trochid is a West Indian
species which sometimes occurs in Florida. It lives about coral
reefs and rocky shores, attaching itself in vast numbers to the
rocks. This shell is a favorite refuge for large hermit-crabs. It
is a curious sight in certain of the West India islands to see a
/Livona pica/ shell scrambling up a tree, looking very much out of
place upon the back of some terrestrially inclined crustacean. When
well cleaned it is a beautiful shell, with black wavy lines over a
greenish-white nacreous foundation. The animal has a row of waving
cirri upon each side of the mantle, and long, slender tentacles.
It is largely used as an article of diet in the West Indies and
Central America. (Plate LXVII.)
FAMILY ~TURBINIDÆ~
This family is very closely allied to the trochids, the most striking
difference being in the operculum, which in the /Turbinidæ/ is
calcareous and usually smooth and very convex on the outside.
[pg363] The shells are nacreous within, and the animal, with its rows
of waving cirri upon each side, is very suggestive of /Trochus/. They
are, for the most part, shallow-water or littoral forms.
[Illustration: PLATE LXVI. 1, Lucapina crenulata. 3, Chlorostoma
brunneum. 2, Haliotis splendens. 4, Neritina reclivata, enlarged. 5,
Trochiscus norrisi.]
[Illustration: PLATE LXVII. Livona pica, reduced. Turbo castaneus,
enlarged. Nerita peleronta. Chlorostoma funebrale. Nerita tessellata.]
GENUS ^Turbo^
^T. castaneus.^ This species has a range as far north as Cape
Hatteras, and is especially abundant at Tampa, on the west coast of
Florida. The peculiar operculum is sufficient to identify the genus
at once. One variety of this species has a crenulated shoulder upon
the body-whorl and is referred to as ^Turbo crenulatus^, A series
of intermediate forms establishes the specific identity of the two
varieties. (Plate LXVII.)
FAMILY ~NERITIDÆ~
The /Neritidæ/ are strictly littoral forms, almost entirely confined
to the warmer waters of tropical seas. The animal preserves the usual
diatocardian features—has a short snout and long tentacles. Unlike
the trochids and /Turbo/, it has no cirri along the epipodial margin.
The shells are peculiarly shaped, the spire being greatly flattened
and scarcely noticeable on account of the unduly large development
of the body-whorl; thus the shell takes on a decidedly patelliform
appearance. It is without an umbilicus. In the principal genus
/Nerita/ the outer lip is sharp on the edge, but greatly thickened
just within.
GENUS ^Nerita^
^N. peleronta.^ This shell has two teeth on the wide, flat
columellar lip, and about them is a blotch of red, suggesting
blood. The common name of this shell, "bleeding-tooth," is very
appropriate. Found in southern Florida. (Plate LXVII.)
^N. tessellata^ is a smaller species, with heavy revolving ribs,
and is further decorated with transverse oblique black lines. The
operculum is calcareous. Both of these species have the habit of
absorbing the entire inner portion of their shells. They belong
to the West Indian fauna, and occur in great numbers on rocky or
coral shore stations. They also may be found on the east Florida
coast, well to the south. A third species, ^N. versicolor^, often
occurs, associated with the other two. It is somewhat smaller than
the others and can easily be distinguished by the four teeth on
the columellar lip, the edge of the columella being convex. (Plate
LXVII.)
GENUS ^Neritina^
The genus /Neritina/ is very closely allied to the last, having quite
the same form of shell; but it is usually more globular and [pg364]
variously ornamented by bright spots or zigzag lines of coloration.
The neritinas have acquired the habit of ascending rivers, until
they have become almost wholly a brackish- or fresh-water genus.
The metropolis of this genus is in the South Sea Islands, where it
attains a wonderful development in the clear running streams of the
volcanic islands.
^N. reclivata.^ A very pretty olive-green species, with very
fine, wavy, longitudinal lines of coloration, found in almost
all Floridian streams above the action of the tide. The nacre of
the columella and within the aperture is bluish-green, and the
operculum is rich olive. (Plate LXVI.)
^N. viridis.^ A small, intensely green species, which, unlike most
neritinas, is strictly marine. It belongs to the great West Indian
faunal province, but is occasionally found upon the shores of
Florida and of Texas.
The prosobranch gasteropods thus far considered (belonging to the
suborder /Diatocardia/) all show by their anatomical structure that
the process of visceral torsion, though carried very far within them,
has not been complete enough to crowd out and finally destroy one
of each of the paired organs. Both auricles of the heart (with some
exceptions) were left intact.
SUBORDER ~MONOTOCARDIA~
In this the second suborder of the prosobranch gasteropods, the
twisting visceral process has been carried to the extreme. The
heart has but one auricle. There is but one gill (on the left
side), and this is attached to the inner side of the mantle flap.
In other respects the presence of certain specialized organs would
probably indicate that gasteropods belonging to this suborder are
a step higher in the scale of life than those which belong to the
/Diatocardia/.
FAMILY ~JANTHINIDÆ~
GENUS ^Janthina^
The genus /Janthina/ has an exceedingly thin and semi-transparent
shell, deep violet in color on the base and lighter blue on the
spire. An interesting feature of this genus is the mode of depositing
the ova. The female exudes from a gland in the foot a [pg365]
glutinous secretion which hardens in water, and, being filled with
air-bubbles, constitutes a float. On the under side of this are
deposited the eggs in rows of little capsules. While attached to this
float it is impossible for a /Janthina/ to sink, and hence it is that
so many of these creatures are sacrificed in onshore gales of wind.
^J. fragilis.^ The shell of this species is so brittle and fragile
that it is very clearly not adapted to a life near shore. It is in
reality a pelagic species which is occasionally blown ashore during
easterly gales along the Atlantic coast of the United States. Vast
numbers of these pretty creatures are sometimes encountered far out
at sea, floating quietly on the surface. When storms drive them
upon the beach, they become utterly helpless; since their foot
is not adapted for crawling upon the sand, they soon perish, and
their brittle shells are demolished by the surf. In Florida the
beaches are sometimes fairly lined with /Janthina/ shells, which
make a band of purple along the high-tide mark as far as the eye
can reach; then it may be years before they again appear. (Plate
LXVIII.)
[Illustration: /Janthina fragilis/: /FL/, float; /O/, ova; /Pr/,
proboscis; /Br/, branchiæ; /F/, foot.]
FAMILY ~SCALIDÆ~
GENUS ^Scala^
The shells of /Scala/ have such a peculiar scheme of decoration
that once seen they can never be mistaken. They are generally
pure white, with well-rounded whorls, all of which are crossed
at even distances by greatly elevated and smooth ribs. Each rib
represents a rest-period, when the creature thickened the rim
of the shell-aperture. The aperture is generally round, with a
continuous lip. The animal has a retractile proboscis and long,
slender tentacles with eyes at the outer bases, and is a predaceous,
[pg366] carnivorous creature. Some Asiatic species of this genus,
remarkable for their beauty and rarity, have been greatly prized by
collectors. A single specimen of the now well-known ^S. pretiosa^ of
China has been sold for two hundred dollars—a fancy price, indeed,
for a shell which can now be bought for a dollar! There are over
fifty species of /Scala/ on the Atlantic coast, but most of them are
either rare or belong to a zone of deeper water; there are, however,
four or five species which are exceedingly common.
^S. lineata.^ A species which ranges from Hatteras to New England.
It has about eight whorls, and is slightly brownish in color. The
ribs are robust and not greatly elevated; there are from seventeen
to nineteen on the body-whorl. The shell is sometimes painted with
a few revolving brownish lines.
[Illustration: /Scala lineata./]
^S. multistriata.^ The transverse ribs are much smaller but very
numerous; the small spaces between them are marked with many fine
revolving lines. Found from Cape Cod southward.
[Illustration: /Scala multistriata./]
^S. groenlandica.^ Essentially an arctic species, which has found
its way down to the New England coast. It is readily distinguished
by the flattened, coarsely rounded, revolving ribs, which follow
the volutions of the spire. Over them are the usual transverse
heavy ribs peculiar to this genus.
[Illustration: /Scala groenlandica./]
^S. angulata.^ The whorls touch one another only by the ribs,
of which there are nine to each volution. This species has a
remarkably wide range, occurring from Cape Cod to southern Florida.
(Plate LXVIII.)
These four species vary from one half of an inch to one inch in
length. All of them are found on the beach after storms or may be
dredged in shallow water near the shore.
FAMILY ~NATICIDÆ~
This large and interesting family is well represented in the Atlantic
waters of the United States, but its more beautiful members live
in the tropics. The New England and New Jersey species are dull in
color, but offer much of interest to the collector and student. The
foot is enormously large, and carries in front a great shield-like
fleshy process, which curves back over the head of the animal and
serves as a plow in pushing its way through the heavy wet sand of
the beach. When the creature is thus seen extended in the act of
crawling, one wonders how it is possible for it to withdraw so great
an amount of body into its shell; but if it is suddenly seized or
irritated, it will quickly [pg367] demonstrate its ability
to hide itself completely within its house and to close the door
very effectively by means of its operculum. The eyes seem to be
wanting, or they are concealed under the skin of the head. The shell
is usually quite large, with a depressed spire and well-rounded
whorls—especially the body-whorl, which appears to be greatly
swollen. The umbilicus is usually open and moderately large, the lip
simple.
[Illustration: PLATE LXVIII. Janthina fragilis. Sigaretus
perspectivus, upper side. Scala angulata, enlarged. Sigaretus
perspectivus, under side. Natica canrena. Crepidula aculeata.]
GENUS ^Polynices^ (^Lunatia^, ^Natica^).
^P. heros^ (generally referred to as ^Lunatia^ or ^Natica
heros^). One of the commonest large shells and one of the most
characteristic species of the New England and New Jersey littoral
fauna. It is exceedingly common along the Long Island shore, where
it may be found on the open beach, in pools with a sandy bottom
left by the receding tide. It is usually partially and frequently
wholly buried in the sand. The umbilicus is open and large, the
operculum corneous, and the shell heavy and ashy-white to brownish,
with (when young) a yellowish epidermis. Its length is from two to
four inches. It has no ornamentation whatever. /P. heros/ is a most
voracious creature and spends its time in hunting for flesh—either
alive or dead—to devour. It feeds upon dead fish, or upon other
mollusks whose shell it is able to pierce by means of its radula,
making a little round hole through which it sucks out the flesh
from within. The curious egg-cases of this species have already
been referred to. (See Plate I.) It glues together particles of
sand into the form of a basin with the bottom knocked out and
broken on one side. In the gelatinous substance of this basin it
deposits its eggs in a regular order. These hatch out in midsummer.
Egg-cases of this kind can always be found wherever /Polynices/
lives. For a long time naturalists were greatly puzzled by these
curious things, and their blunders are recorded in earlier works,
where these egg-cases have been elaborately described as living
animals belonging to various invertebrate orders. The largest and
best specimens of /P. heros/ are to be found south of Cape Cod.
(Page 343.)
^P. triseriata.^ A small shell of exactly the same shape as /P.
heros/, but decorated with three revolving series of bluish or
chestnut spots. It is pretty well determined that this so-called
species is only the young of /P. heros/. It is very abundant all
along the coast.
[Illustration: /Polynices triseriata/, young; /Polynices
triseriata/, older specimen.]
^P. duplicata.^ This is even more abundant than /P. heros/. It
has a flatter shell, with an obtuse apex and dome-like spire.
The umbilicus is partly or wholly closed by a thick, callous,
shelly process thrown off from the columellar lip, and is chestnut
in color. The surface of the shell is smooth, often polished,
ashy-white below and light chestnut above. The operculum is
corneous. The length of the shell varies in different localities
from one half of an inch to about two [pg368] inches; the breadth
slightly exceeds the length. /P. duplicata/ has a very extensive
range, from the Gulf of Mexico to Newfoundland. The largest and
finest specimens are found in the vicinity of New York and at
Hatteras. In Florida they are usually smaller. This species cannot
be confounded with any other upon our coast on account of the heavy
callous deposit over the umbilicus. Its habits are similar to those
of /P. heros/.
[Illustration: /Polynices duplicata./]
[Illustration: /Natica clausa./]
^Natica clausa.^ A Northern species which is fairly abundant on the
Maine coast. It has a shelly operculum, and the umbilicus is neatly
closed by a pure white, shining callosity. Its length is about one
half an inch, its color livid white to light brown, white within.
The calcareous operculum at once determines this shell. This
species (as well as the following one) has retained the generic
name of /Natica/ because of the shelly operculum, as explained
below.
^N. canrena.^ One of the handsomer species of /Natica/, which
occurs in Florida. Sometimes it is seen as far north as Hatteras.
The shell is white, with bars of light chestnut circling the
whorls, and with zigzag lines of darker purplish hue crossing them.
The base of the shell is white. The aperture is large and flaring,
and is purplish within. The umbilicus is partially closed by an
entering callous plug. The operculum is calcareous, with eccentric,
deeply cut grooves. Found in sandy stations just about low-water
mark. (Plate LXVIII.)
^P. lewisii.^ A species which occurs on the west coast of the
United States. It resembles its New England relative /P. heros/
very closely. /P. lewisii/ is a Northern species, and does not
range south of Oregon. Professor Keep mentions one specimen of the
size of a six-inch globe, but such dimensions are very unusual. A
good-sized specimen need not exceed four inches in height.
^P. recluziana.^ A species well known on the southern coast of
California. The umbilicus is closed by a thick, highly polished
white callosity, and the general shape of the shell is strongly
suggestive of the common east-coast species /P. duplicata/. A large
specimen is about two inches in diameter.
[There has been much confusion in the generic nomenclature of
this family. The old name /Natica/ once did service for all the
species; then the names /Lunatia/, /Neverita/, and /Polynices/ were
applied to certain special forms; but it has been wisely proposed
by conchologists to use the name /Natica/ for those forms having
a shelly operculum, and to adopt the name /Polynices/ for those
having a corneous operculum. /Lunatia/ and /Neverita/ have become
subgenera of /Polynices/.] [pg369]
GENUS ^Sigaretus^
A very interesting species of this genus occurs on the east coast,
sparingly in New Jersey, but very abundantly south of Hatteras.
/Sigaretus/ is a modified /Natica/. The spire is flattened and
minute. The body-whorl, being greatly expanded, gives a wide,
flaring, oblique aperture. The shell is ear-shaped and white, with
fine revolving lines. There is no umbilicus. The operculum is small
and rudimentary. The animal is large, with an enormous foot and
greatly developed propodium, and is a sand-dweller. The common
east-coast form is ^S. perspectivus^. (Plate LXVIII.)
FAMILY ~CAPULIDÆ~
GENUS ^Crepidula^
[Illustration: /Crepidula fornicata./]
^C. fornicata.^ All collectors of mollusks on the Atlantic coast
sooner or later encounter this exceedingly common species adhering
to oyster-shells or scallops, and often to other large live shells.
It is cast upon the beach along the entire length of the Atlantic
coast. The shell is obliquely oval, dull whitish in color, and
either smooth or rough or even ribbed, according to the nature
of the surface to which it clings. The spire is almost entirely
suppressed, the little inconspicuous apex being turned to one
side and closely pressed down against the body of the shell. When
looking into the interior of the shell one is reminded of a boat,
for the upper portion of the aperture is covered by a horizontal
shelly partition, called the diaphragm, a space being left below
which would correspond to the forecastle of a ship. The "stern" is
round, and the "bow" is suggestively pointed.
[Illustration: /Crepidula plana./]
^C. plana.^ In this species the shell is white and flat, or
slightly concave. Although it is pointed at the "bow" end and
square at the "stern," the nautical resemblance stops there,
because, being flat, there are no swelling sides and bow. The
diaphragm is about one half the length of the shell, convex,
shining, white, and translucent. /C. plana/ lives generally within
the aperture of large dead shells. It has a wide range, from Maine
to Florida.
^C. aculeata.^ A common Floridian species which has a remarkable
range, being found in nearly all the tropical and semi-tropical
waters of the world. It is smaller than /C. fornicata/, is
reddish-brown with a white diaphragm, and has several radiating
ribs on the back, which are inclined to be nodulous. (Plate
LXVIII.) [pg370]
On the Pacific coast the following species are found: ^C. adunca^,
with a strongly recurved apex, and less than one inch long; ^C.
rugosa^, rough, brown, with the apex lying on the edge of the
shell, and one inch in length; ^C. navicelloides^, almost identical
with the east-coast /C. plana/. /C. aculeata/ also appears.
GENUS ^Crucibulum^
/Crucibulum/ has a peculiar rounded shield-like form, with a very
small apex on one side. Within there is a cup-shaped appendage
attached by one side to the inner margin of the shell. This latter
feature at once determines the genus.
[Illustration: /Crucibulum striatum/, from above.]
[Illustration: /Crucibulum striatum/, from below.]
^C. striatum.^ This species has radiating riblets, cut by circular
lines of growth. No dimension would quite reach an inch. It is a
common shell on the Atlantic coast, and will be found adhering
to stones and other shells, but it is not, strictly speaking, a
littoral species.
^C. spinosum.^ The shell exhibits a strong tendency to spinous
processes on its back. Found along the southern part of the
California shore.
FAMILY ~LITTORINIDÆ~
GENUS ^Littorina^
/Littorina/ is probably the most characteristic genus of Northern
littoral regions. Together with some of its allied genera it is also,
probably, equally characteristic of various tropical littoral faunas
all over the world. The family comprises strictly between-the-tides
genera and species. Indeed, it is suspected that some species of
/Littorina/ are making very fair progress toward a terrestrial
condition, for they actually live above high-tide mark,—even in
the branches of overhanging trees,—and must certainly pass days at
a time out of their natural element. That such a transformation is
possible need not for a moment be doubted, for there are many land
mollusks to-day that give abundant evidence of having been at some
past time aquatic or marine species. These changes in nature are
constantly going on, and the gradual substitution of a lung for a
gill is no very startling metamorphosis. [pg371]
The littorinas fairly swarm in favorable localities upon all shore
stations. In Maine and Massachusetts the bold, rocky coast furnishes
a home for several species. Often the rocks at low tide are black
with them; the algæ that cling in wet masses to the exposed rocks
are alive with them. One cannot walk about in such localities
without crushing hundreds of specimens. Sometimes they will be found
clinging in clusters upon the piling of old wharves, or crawling
about the bottom at or about the low-tide mark. The best specimens
of /Littorina/ are found in stations where they are bathed twice a
day by pure, uncontaminated sea-water; those living near the mouths
of streams, or where the water is brackish or impure, are usually
small and degenerate. They are vegetable feeders, and have received
the common name of "periwinkles." In Great Britain they are used
among the poorer classes for food. The animal has a short, broad
muzzle, and eyes at the outer bases of the tentacles. The foot is
longitudinally grooved, and there is a rudimentary siphonal fold in
the mantle. The shells are turbinated, usually heavy, few-whorled,
and with a round aperture.
[Illustration: /Littorina litorea./]
^L. litorea.^ This is supposed to be an importation from the Old
World—to have come over by way of Iceland and Greenland, and
then to have migrated down the Labrador coast. For many years
Cape Cod formed a barrier to its advance, but now the species is
abundant at Newport, and is reported at New York. It occurs on
the Maine coast in astonishing numbers, living in vast colonies
on the rocks exposed at low tide. The shell is thick, imperforate
(no umbilicus), and usually has flat, spiral ribs. The columella
is broad and white; the lip thin and black. The general color
varies from black to olive or to dingy gray—sometimes reddish.
The operculum is corneous, with the nucleus near the outer edge.
Despite the variableness of this very common shell (the variations
being chiefly in the height of the spire), it has certain
unmistakable characteristics which, once seen, will enable the
collector to determine it at once.
[Illustration: /Littorina rudis./]
^L. rudis.^ A smaller species than the last. It is strong
and coarse, with revolving grooves and ribs, or smooth, with
interrupted whitish bands and spots. A very common variety of
this species is much smaller than the typical form, being about
one sixth to one fourth of an inch long, smooth, with white and
yellowish spots on olive. It clings to the rocks near high-tide
mark, and is usually found attached to its resting-place by a
bit of hardened mucus. While the typical /L. rudis/ is heavy and
banded, with a moderately high spire and no color, this [pg372]
variety is thinner, with a higher spire and smoother surface,
and has a color-scheme of decoration. It would be impossible
to disconnect the two, for a large series of specimens will
demonstrate beyond doubt, through every minute degree of variation,
that the two forms belong to one and the same species. The station
of /L. rudis/ is much the same as that of /L. litorea/, but the
smaller colored variety of /rudis/ prefers quieter and more
sheltered spots. It is occasionally found on reeds and grasses,
on the piling of wharves, on large boulders above the line of
algæ, and on algæ. It has been the writer's experience not to find
/rudis/ and /litorea/ associated together.
[Illustration: /Littorina palliata./]
^L. palliata.^ A low-spired, globular shell with a large, tumid,
smooth body-whorl. The columella is flattened, curved below, and
imperforate. The color is exceedingly variable, but is usually
bright, shining olive, and this is especially the case with those
individuals that find their station in the dense masses of algæ
that form so conspicuous a feature of a low-tide scene on a rocky
New England coast. From pure olive-green to yellow or bright red,
with revolving black bands, seems a long chromatic leap, but it
is not too great for the Designer of these pretty little globular
shells. As a rule, the color of the shell simulates pretty closely
that of the seaweed upon which it lives, and inexperienced eyes
may easily overlook hundreds of specimens, all within close reach.
The banded varieties are less common. The head of the animal is
somewhat orange in color, the foot slate. The distinguishing
features of this species are the smooth, globular shell, the low
spire, the broadly flattened columella, and the orange-colored head
of the animal. It is found on /Fucus/ between tides, and often
associated with /L. rudis/, on the whole coast north of New Jersey.
The three preceding species are distinctly boreal in their range,
but their place is taken in southern Atlantic waters of the United
States by the following exceedingly common species:
[Illustration: /Littorina irrorata./]
^L. irrorata.^ A solid, robust shell, which attains a length of
about one inch. It is in many respects suggestive of /L. litorea/,
its Northern relative, but the spire is higher, with straighter
outlines, and the apex is acute. The surface is ornamented with
closely set, revolving ribs; the sutures are indistinct; the lip
is thin, though thickened just within; and the color is whitish to
pale cinereous greenish, sometimes spotted with broken brownish
lines. Within it is white, with a reddish tinge on the columella,
and brownish spots on the edge of the lip. This species ranges from
Maryland to Texas; its station is between tides.
^L. angulifera.^ As the last species resembles /L. litorea/, so
this other common Southern form resembles a greatly developed and
large /L. rudis/ of the smoother variety. It has a high-spired
shell, with an acute black tip. It has about six whorls, which are
variously decorated by wavy, oblique black lines and revolving
black lines broken into series of dots and larger spots near the
suture. The ground-color varies from yellow to purple. None of
the colors are very vivid. Within it is yellowish-white. This
species has a much thinner and more delicate shell than any of
the littorinas thus far considered. It is common on the piling of
wharves and in sheltered nooks everywhere [pg373] between tides.
It is essentially a tropical species of very wide and extended
range, but it does not occur north of St. Augustine. At Tampa it
has been found in vast numbers. (Plate LXIX.)
The California coast furnishes two more species of /Littorina/.
Their station is among the rocks between tides, and their habits
are quite the same as those of the east-coast species.
^L. scutulata.^ In this species the color is of various shades,
generally dark gray, mottled with white spots. A good-sized
specimen measures one half of an inch in length. The spire is high;
the columella flattened, broad; the shell is purplish-white within
the aperture. (Plate LXIX.)
^L. planaxis.^ Somewhat larger than the last; wider; with a lower
spire; grayish in color, sometimes speckled with white; chest
nut-brown within. The columella is remarkably flattened, and a
portion of the whorl next bordering the columella is excavated as
though eaten away by the animal. These two species are often found
associated on the rocks. (Plate LXIX.)
GENUS ^Lacuna^
[Illustration: /Lacuna vincta./]
Closely allied to /Littorina/ is the genus /Lacuna/, one species of
which, ^L. vincta^, is very abundant on the New England coast. A
curious and distinguishing feature of this genus is the umbilicus,
which forms a lengthened groove along the columella. /L. vincta/
rarely exceeds one half of an inch in length, and is thin, with a
pointed spire of five whorls. It is either of a uniform horn-color,
or purplish, or banded with chestnut. It may best be found upon
marine plants in sheltered places, or may sometimes be gathered in
quantity from the roots of /Laminaria/ washed in by storms.
GENUS ^Tectarius^
The specific representatives of this genus are mostly tropical. ^T.
nodulosus^ is abundant in Florida. It is about one half of an inch
long, and has the flattened columella and round mouth characteristic
of /Littorina/. It is decorated somewhat elaborately by revolving
rows of nodules which cover the entire shell. Its station and habits
are the same as those of /Littorina/.
FAMILY ~CERITHIIDÆ~
In this family we meet with a somewhat new type of shell—the long,
turriculate shell, with many whorls and with a channeled [pg374]
aperture. The /Cerithiidæ/ include a large number of genera, mostly
tropical in distribution. Their shells are usually highly ornamented
in various schemes of sculpture, but they lack beauty in color. The
animal is provided with a siphon, as is indicated by the anterior
canal of the shell. The operculum is corneous, with a nearly central
nucleus.
GENUS ^Cerithium^
^C. floridanum.^ A very common species on the west coast of
Florida, also sparingly found at Hatteras. It has eight or ten
whorls, a gradually tapering spire, and a sharp apex; the aperture
is oblong, with a deeply cut anterior canal projected to the left
and backward (when the specimen is held apex up, with the aperture
toward the observer). The sculpture is elaborate, consisting of
many rows of revolving ribs, and close to the suture there are
circling rows of nodes. There is a curious hump just to the left
of the aperture, which is quite characteristic of the genus. The
color is whitish-gray; the length one and a quarter to one and a
half inches. Station, shallow water in lagoons and sheltered spots.
(Plate LXIX.)
^C. muscarum.^ Another Floridian species, somewhat smaller than the
last (one inch in length). It has heavy, prominent, transverse ribs
crossed by circling rows of chestnut spots, one heavy revolving
rib around the base; eight or nine whorls; a high-tapering spire;
and a sharp apex. The aperture is oblong, with the anterior canal
projecting to the left. The columella is arched; the color shining
gray to very light purplish. This very pretty little shell may be
gathered literally by the shovelful all along the west Florida
coast in sheltered spots, on sandy and shallow bottoms. (Plate
LXIX.)
^C. minimum.^ A still smaller Floridian shell, with jet-black
aperture and anterior canal projecting horizontally to the left.
The sculpture-plan is of revolving ribs and a series of white
granules just below the sutures. Its station is the same as that of
the last. Often the bottom of a lagoon will seem to be literally
paved with these somber-hued little shells. From Tampa Bay to
Charlotte Harbor they are very abundant.
GENERA ^Bittium^, ^Triforis^
These are allied genera, having numerous species upon our coasts, but
the shells are so small that the inexpert collector is not likely to
notice them. Hosts of these minute, turreted, decussated, blackish
shells are to be found on the wiry grasses of salt-marshes. They are
also found on algæ at low-water mark. In /Triforis/ the whorls turn
to the left. Range from Cape Cod to South Carolina. [pg375]
GENUS ^Cerithidea^
^C. scalariformis.^ This species has the suggestive outlines of the
family, but the aperture is simpler. The outer lip is considerably
thickened, sinuous, and yellow; there is a very slight notch at the
angle of the columella, and the lip serves for an anterior canal.
The apex is wanting by reason of the usual truncation of two or
three whorls of the spire. There are revolving ribs on the base;
longitudinal ribs elsewhere. The color is a dingy drab; within,
brownish-yellow. It is found in brackish water in Georgia and
Florida. This species is said to suspend itself from overhanging
vegetation by means of glutinous filaments. It may remain out of
water for an almost indefinite time. (Plate LXIX.)
^C. sacrata.^ A species very common on the mud-flats of San
Francisco Bay. It is a high-spired shell of ten heavily ribbed
whorls, with a series of revolving ribs on the body-whorl. The
outer lip is sinuous, and the columella is slightly twisted. It is
nacreous and brown within, dingy blue-black without. Length one
inch to an inch and a quarter. (Plate LXIX.)
FAMILY ~VERMETIDÆ~
GENUS ^Vermicularia^
[Illustration: /Vermicularia spirata./]
^V. spirata.^ This is a very curious creature when considered from
the point of view of the gasteropod mollusk. It seems at first as
though it would be better to regard it as a worm which had created
for itself a calcareous covering. But it is a true prosobranch
notwithstanding the fact that it has departed widely from the
conventional design in the fashioning of its shell. At first the
shell starts out in a regular form, and then the whorls become
separated, finally wandering about in a seemingly aimless manner.
The irregular prolongation sometimes measures ten inches in length.
The animal is in no way remarkable except in having the viscera
greatly elongated and the foot very short and broad. The color of
the animal is light brown with black spots; the shell-color is
rufous or ashy-white. Shells of this genus are often found grouped
together in an inextricable mass. It is found in shallow water from
New England to Florida.
FAMILY ~STROMBIDÆ~
This is a particularly interesting family, but it is tropical, and is
represented on the shores of the United States by only one [pg376]
genus, /Strombus/, of which we have but a few species. /Strombus/
is a scavenger,—a buzzard among mollusks,—and its sense of smell
is evidently very acute. Its eyes are much more highly developed
than the usual gasteropod visual organs, and they are placed at
the tip-ends of two very substantial eye-stalks or-pedicels. The
tentacles are slender and project from the eye-pedicels. The foot
is curiously developed; that portion of it which would naturally
constitute the creeping-disk is exceedingly small, but the metapodium
(the hinder part of the foot, upon which the operculum is situated)
is very large. The corneous operculum upon its end, which is far too
small to close the entrance of the shell when the creature retires
within it, looks like a claw. Instead of creeping along the sand,
/Strombus/ proceeds by jumps or awkward leaps, turning its heavy
shell first to one side, then to the other. The shell is usually
heavy, with the outer lip greatly thickened.
GENUS ^Strombus^
^S. pugilis.^ The very common Floridian species, often three to
four inches in height, with a short spire covered with nodes or
short, obtuse spines, which are also found upon the shoulder of the
body-whorl (sometimes smooth). The aperture is long, with a wide
notch in the outer lip and a posterior canal. Living specimens have
a tough, leathery epidermis covering at least the body-whorl. The
color is brownish. The columella is covered with a fairly thick
callous deposit, and, as within the aperture, is highly polished,
and deep purple, blackish-chestnut, or vivid carnation-red in
color. The smoother varieties have gone under the name of ^S.
alatus^, but the identity of the two species is assured. This
pugilistic /Strombus/ is a very active mollusk, and when placed in
a boat will sometimes effect its escape over the side in a most
surprising manner. The species is very abundant in all the shallow
waters of Florida. A piece of meat on a string, left overnight in
some sheltered sandy spot where there are from six to eight feet of
water, will surely attract them. In Florida, where the waters teem
with life, unless the bait is protected in a wire cage, the chances
are that the hosts of crustaceans and fish will make away with it
long before the strombs can arrive on the scene. (Plate LXX.)
^S. gigas.^ One of the largest of gasteropods, very common on the
Florida Keys and also occurring in southern Florida. Hundreds of
thousands of these shells have been sent to Europe from the Bahamas
to be cut into cameos. This familiar shell is to be seen everywhere
in the South, placed about flower-gardens and lining the paths
and walks in yards. It is generally known in Florida and the West
Indies as the "conch-shell." The animal is used as food in Key
West, and is very generally eaten throughout the Bahamas. From
their habit of eating [pg377] these animals the natives of some
of the Bahama Islands are themselves called "Conchs." The rich pink
color of the shell is very striking.
There are perhaps seventy-five or eighty species of /Strombus/
inhabiting the tropical seas, and many of them are highly prized by
collectors on account of their great beauty.
[Illustration: PLATE LXIX. 1, Littorina angulifera, twice natural
size. 2, Littorina scutulata, much enlarged. 3, Littorina planaxis,
enlarged. 4, Cerithium floridanum. 5, Cerithium muscarum. 6,
Cerithidea scalariformis, enlarged. 7, Cerithidea sacrata.]
[Illustration: PLATE LXX. 1, Strombus pugilis. 2, Cypræa exanthema.
3, Trivia pediculus. 4, Trivia californica. 5, Trivia quadripunctata.]
FAMILY ~CYPRÆIDÆ~
GENUS ^Cypræa^
/Cypræa/ is one of the "aristocratic" genera. Whether the shell
or the animal itself is considered, there is probably no genus of
mollusks which offers so much of beauty and interest to the collector
and student. The genus is a tropical one, and finds its metropolis
among the coral-fringed islands of the equatorial Pacific. Despite
their brilliant colors and general attractiveness, the cowries—for
such is their popular name—are very modest and shy; they prefer to
hide among rocks, where they may be secure from molestation, for
probably their conspicuous appearance is a real source of danger
to them. In the animal of /Cypræa/ the mantle is provided with two
large lateral lobes, which are reflexed and meet over the top of the
shell; thus, when the mantle is fully extended, the shell is entirely
concealed. These mantle lobes are often furnished with numerous
forked, tufted, or ramified filaments. The foot is long; there is
no operculum. The color of the animal is often very striking in its
intensity. A description of the cowry-shell is hardly necessary, so
familiar is every one with it. A deposit of enamel is made all over
the shell, and its painting and decoration, usually very elaborate,
is reserved for the adult as a final process in the artistic
completion of its home. The aperture is as long as the shell, is
channeled at both ends, and is toothed along both margins. The spire
is insignificant and is concealed by layers of enamel. In the young
the shell has a very different appearance, resembling a sharp-lipped
/Oliva/, and its scheme of coloration may be entirely different from
that employed by the adult.
Among the /Cypræidæ/ are many remarkable species. The splendid
^Cypræa aurantia^, a native of the Fiji Islands, is one of the
shells most sought after by enthusiastic collectors. The natives
[pg378] learned its value long ago, and hold specimens of it at very
substantial prices. It is worn as an ornament by chiefs and as a mark
of distinction. The well-known ^C. moneta^, also a native of the
Pacific Islands, has been very extensively used as money throughout
the South Seas and in Africa. There are many collectors of shells who
confine their efforts almost exclusively to this and to one or two of
the other "aristocratic" genera. From an esthetic point of view this
is very natural, but biologically the less pretentious mollusks are
quite as interesting.
Of the one hundred and fifty or more species in existence only three
are to be found upon the Atlantic coast of the United States, and the
chances are decidedly against the finding of any of them north of
extreme southern Florida.
^C. exanthema.^ A species not uncommon at Key West, where it may
be seen slowly crawling about the mangrove roots near the water's
edge. It attains a length of from four to six inches, and is so
highly polished that a good specimen could be used as a mirror. In
color it is shining, light chestnut, clouded with purple; the lips
are a dark, very rich chestnut; over all are whitish spots which
appear to shine forth from beneath the enamel. Lengthwise along
the middle of the back is a zone of lighter color which reflects a
purplish sheen. (Plate LXX.)
^C. spurca.^ Another Floridian species, properly belonging to the
West Indian fauna. It is not more than one half an inch long, and
is white in color, but it is so thickly dotted with yellow spots
upon the back that it would pass for a yellow shell. The base is
pure white. The surface of the shell glistens in the light.
GENUS ^Trivia^
In the genus /Trivia/ the shell is shaped in every way like that
of /Cypræa/, but its surface is never smooth. In the middle of the
back is a longitudinal groove, from which run transverse ribs, which
continue around to and enter into the aperture. The shells are always
small, never exceeding one half of an inch in length, and their color
is generally reddish or brownish, passing to pink.
^T. pediculus.^ A Floridian species, first described by the great
naturalist Linnæus. Like most of the descriptions of the earlier
naturalists, this is very short and inadequate, and would apply
equally well to almost any /Trivia/. The color is rose-pink, with
several large brownish splashes on the back. The spire is entirely
hidden. It is found in shallow water in pools, and on the beach
after storms. (Plate LXX.) [pg379]
^T. quadripunctata.^ Much smaller than the preceding; rose-red,
with four conspicuous reddish-brown dots on the back, two on each
side of the median dorsal groove. Found in Florida. (Plate LXX.)
On the California coast are also several species of /Trivia/ and
one /Cypræa/, but they belong to the Southern California peninsula,
and are not commonly found farther north than Santa Barbara. The
cowry is called ^C. spadacea^; it grows to a length of about two
inches, is highly polished, with white base and sides, and is
bright chestnut above. As is usual in the cypræas, the spire is
covered with enamel.
^T. californica.^ A species found at Monterey and thence south.
It lacks the median dorsal groove, and has a whitish color-streak
instead. The ribs are white, and the ground-color of the shell
is dark brownish-red. These little shells, when found upon the
beach, are called "coffee-shells," from their somewhat striking
resemblance to the coffee-bean, being flat on one side and rounded
upon the other, and otherwise resembling it in size and color.
(Plate LXX.)
^T. solandri.^ This species may be found at Santa Barbara and San
Diego. It is twice as large as the last species, and has a very
deep groove in the back and widely separated ribs. Color rose to
brown. The groove on the back penetrates into the white portion of
the shell.
FAMILY ~DOLIIDÆ~
This small family furnishes two conspicuously handsome species
belonging to the genus /Dolium/, which range from Hatteras southward
into the West Indies.
GENUS ^Dolium^
^D. galea^ and ^D. perdix^. The animal in both of these species
has a relatively large foot, which spreads out while in the act
of creeping and seems far too bulky ever to be withdrawn into the
shell. It is square in front, and, bulging out far to each side,
tapers to a blunt point behind. The most noticeable feature of the
animal, however, is the great development of its proboscis, which
is quite as long as the shell itself. The siphon is also long and
is curved over the back of the shell. The operculum is wanting in
adult specimens. The shell of /D. galea/ sometimes attains a length
of eight inches, with a diameter of about six inches; the other
species is not quite so large. They are both ventricose, thin,
inflated shells, with large body-whorls and crenulated lips. Both
are slightly umbilicated and ornamented with revolving, regularly
spaced ribs. The ribs of /D. perdix/ are not so highly raised,
but they are painted with light reddish-brown spots. /D. galea/
is white, with a lower spire and deeply channeled sutures. (Plate
LXXI.)
GENUS ^Pyrula^
^P. papyratia.^ One of the commonest as well as one of the
handsomest of American shells. It is a Floridian species, found in
shallow water and on sandy bottoms. The animal greatly resembles
that [pg380] of /Dolium/, except that it has two side-flaps,
which, when extended, partially inclose the shell. The shell is
thin, with an almost flat spire and a greatly enlarged body-whorl.
The aperture is flaring, and is drawn out anteriorly into a
tapering canal, which gives to the shell the outlines of a pear.
The ornamentation is revolving, but not highly raised, and there
are ribs with very distinct longitudinal lines of growth between.
The color is pure white, or sometimes yellowish, with rufous spots;
within it is golden. This attractive shell is usually from three to
four inches in length, but is sometimes found considerably larger.
(Plate LXXI.)
FAMILY ~CASSIDIDÆ~
GENUS ^Cassis^
The cassides, commonly known as the "helmet-shells," are carnivorous
mollusks, which lead an active life in sandy stations, prowling
about in search of bivalves, upon which they prey. They have a large
siphon and a fairly large and extensible proboscis. The foot is
broad and strong, being well adapted for plowing through the sand.
The shell of /Cassis/ is large, generally heavy and inflated, with
a short spire and a short, recurved anterior canal. The lip is much
thickened. Upon the Atlantic coast of North America there are four
species of /Cassis/. They are all properly West Indian in their
faunal relations, but have found lodgment on the American shore at
various points. All of them have been taken in the neighborhood of
Cape Hatteras, two of them in West Florida, and two in Texas.
^C. tuberosa.^ A large, heavy shell, often from six to eight inches
in length, with a flattened spire. The aperture is long and narrow,
with large white teeth upon the outer lip, which is also greatly
thickened. The columellar lip is ribbed. A heavy deposit of enamel
to the left of the columellar lip gives the shell a triangular
outline. A row of very large nodes upon the shoulder of the
body-whorl and two rows of obsolete nodes below are characteristic
features of this species. The color is light yellowish-brown
suffused with pink. The aperture and the columellar callosity are
flesh-tinted, with chestnut trimmings. The anterior canal is deep
and recurved.
^C. cameo.^ A species of about the same size as the last, but
more ovate or ventricose in form. It is coarsely striated, with
elevated growth-lines, and has circling rows of large, rib-like
elevations, having sometimes nodes upon the body-whorl. The
columella is conspicuously ribbed and greatly expanded. The outer
lip is thickened, and has lamelliform teeth within. Flesh-colored;
teeth white; purple-brown trimmings. A great many of these shells
are sent yearly from Nassau [pg381] to Italy, where they are used
in cameo-cutting. It is owing to the fact that the substance of
these shells is deposited in layers of different colors that they
are available for this purpose. There are about fifty species of
helmet-shells, the one most valued for cameo-cutting being known as
the black helmet, /C. Madagascarensis/.
^C. testiculus.^ A species found outside of the West Indies only
at Key West and at Hatteras, where the Gulf Stream has brought so
many West Indian forms, and left them at the point where it takes
its oblique course away from the shore. This pretty species is
smaller than the others just described. It has a low, depressed
spire; longitudinal ribs crossing wide, flat revolving ribs; a
long, narrow aperture; and a reflexed and thickened outer lip,
also toothed. The columella is thickened and ribbed. The anterior
canal is recurved over the back of the shell, as is usual in the
genus. The color is bluish, with dark spots. There are square black
spots on the reflexed lip; the aperture is pink, and the teeth
and columellar ribs white. This species is exceedingly common at
Nassau, and plays havoc with the more slowly moving bivalves, which
it devours. (Plate LXXI.)
^C. inflata.^ Perhaps the commonest species of /Cassis/ on our
coast. It is reported to be common at Beaufort, South Carolina, yet
it is not so frequently met with out of the West Indies as some
earlier collectors would have us believe. Beach-worn specimens,
however, are not unusual all along the Florida coast. It attains
a size of from three to four inches, and is a rounded, globose,
ventricose shell, with a higher spire than is usual in this
genus. The surface is almost smooth, the series of revolving ribs
being scarcely raised on the body-whorl. The lip is thickened
and reflexed, with prominent lamelliform teeth which continue as
internal ribs. The lower portion of the columella is calloused and
roughly granulated. The color is bluish-white, glazed, with large
square brown spots. The region of the aperture is pure white.
The collector should not remain content with a specimen or two
of the poor beach-worn shells of this species. In general, this
advice applies to the collection of all specimens. One can get
no idea of the sculpturing and painting of shells from dead and
worn specimens. It is quality rather than quantity that makes an
interesting cabinet. (Plate LXXI.)
FAMILY ~MURICIDÆ~
SUBFAMILY ~MURICINÆ~
It seems like making a long leap to pass suddenly from the
/Cassididæ/ to the /Muricidæ/. In the natural biological order, as
it appears in our present state of knowledge, a host of families and
genera intervene between these two. But they are omitted here, either
because they do not conspicuously occur upon our own shores, or
because they are free-swimming pelagic mollusks, which live only far
out at sea and rarely are found on the beaches. The family /Muricidæ/
is an exceedingly large one, including a [pg382] bewildering number
of well-characterized genera. It has many representatives in every
sea, but, as is apt to be the case, the finest and most striking
species are tropical. The animal is not peculiar in any way, being
altogether a conventional prosobranch gasteropod, with moderately
long foot, and the usual tentacles placed upon a small head. There is
a retractile proboscis, which suggests carnivorous habits. In reality
the /Muricidæ/ are perfect pirates among the /Mollusca/, attacking
nearly every species they encounter, piercing its shell and devouring
the unfortunate inhabitant. They live in rocky and gravelly places or
about coral reefs. Their shells are seldom colored, except about the
aperture. What the shells lack in color, however, they fully gain in
oddness of form and in sculpturing. The anterior canal varies from a
mere notch to an astonishingly long channel. The tendency to nodes,
varices, spires, and varicose processes in general is a prominent
feature of the family.
There are several genera, with numerous species, upon the east and
west coasts of the United States, but we can do no more here than
mention those which are very common.
GENUS ^Murex^
Of this tropical genus there are two Floridian species—/M. rufus/
and /M. pomum/. The genus has been very extensively divided into
subgenera, based upon shell-characters alone. Some of these subgenera
are usually accepted at full generic value, and their substitution
for the old, well-established name /Murex/ is to be expected. These
two Floridian species fall within different subgeneric lines, and the
student who goes to a museum to compare his catch with the labeled
specimens on exhibition will probably be puzzled to find his two
murices named /Chicoreus rufus/ and /Phyllonotus pomum/ respectively.
But for our purposes the name /Murex/ will do well enough.
^M. rufus.^ This species scarcely ever exceeds three inches
in length. Its spire is moderately high, and the aperture is
oblong-ovate, with a long, slightly curved, and almost completely
inclosed anterior canal. Through the end of this the fleshy siphon
projects in life. The shell is most extravagantly sculptured—so
intricately that it is difficult to [pg383] describe it. Its
most conspicuous feature is the large foliaceous varices which
cross the whorls, projecting almost one fourth of an inch from the
body of the shell. Between each of these varices is a large node.
There is, besides all this, a system of pronounced revolving ribs
which cross the varices and nodes, giving to the shell a greatly
roughened appearance. The interior is bluish-white. The operculum
is corneous, with a subterminal nucleus. Unfortunately, this really
handsome shell is usually incrusted with coralline or calcareous
matter, which must be removed with acid before a good idea of
its appearance can be had. In color it is reddish-brown to dark
chestnut on the varices. It is very common on the west coast of
Florida, but rarer elsewhere. (Plate LXXII.)
[Illustration: PLATE LXXI. Dolium galea. Dolium perdix.
Pyrula papyratia.
Cassis testiculus. Cassis inflata.]
[Illustration: PLATE LXXII. Murex rufus. Murex pomum. Ocinebra
poulsoni, enlarged. Pteronotus festivus. Cerostoma foliatum.
Cerostoma nuttallii.]
^M. pomum.^ A more abundant species, found all along the coast
from Hatteras to Texas. It is not so elongated as the last, and
its sculptural design is much less exaggerated. Between each of
the varices are two nodules. The aperture is oblong-ovate, and
the anterior canal is nearly closed and recurved toward the back.
Revolving ribs cross the varices and nodules. The color is ashen,
with chestnut tips upon the nodes and varices, and chestnut-colored
patches about the aperture. The varices are simple and not
foliaceous as in /M. rufus/; the shell is more globose. Length two
to three inches. (Plate LXXII.)
^M. (Phyllonotus) fulvescens.^ The largest of the American murices.
It is not commonly found except in Texas.
GENUS ^Trophon^
[Illustration: /Trophon clathratus./]
^T. clathratus.^ A fairly common shell of the Maine coast;
although it belongs to a deeper zone than that of the tides, it
is occasionally found after storms upon the shore. It is a small
fusiform shell, with many prominent longitudinal ribs and a
produced anterior canal. /Trophon/ is a boreal genus, which finds
the best conditions for life in the icy waters of Labrador and
Greenland.
GENUS ^Urosalpinx^
The genus /Urosalpinx/ is closely allied to /Murex/ and /Trophon/.
Several of its species are found on the east coast of the United
States.
[Illustration: /Urosalpinx cinerea./]
^U. cinerea.^ This well-known species is regarded by Chesapeake and
Long Island Sound oystermen much in the light of a plague. These
active predaceous mollusks live upon bivalves, and preferably upon
oysters. They bore a small round hole through the shell of their
helpless victims, and then proceed to extract the succulent, fleshy
animal from within. The oystermen call them by the suggestive
name of "drill," and wage incessant warfare upon them. In some
years these mollusks appear to go into partnership with the large
starfish, /Asterias/, and the combination of the two can soon
destroy any oyster-bed. The original home of this destructive
little creature is presumed to be in Chesapeake [pg384] Bay, but
the transplanting of oyster-spat thence to Long Island Sound has
introduced the enemy at the same time. The species has a wide range
from Florida to Cape Cod, and locally north of that point; in fact,
it may be counted upon to appear wherever there are oyster-beds.
The shell is dingy gray in color, and its whorls are crossed by a
dozen or more rib-like undulations, and numerous revolving striæ.
The anterior canal is produced, and is yellowish-brown within.
Length under an inch.
GENUS ^Eupleura^
^E. caudata.^ A curiously flattened shell which has close family
connections with that last described. The peculiarly flat
appearance is due to the fact that there is a rather wide varix
upon each side of the shell. It is a small species, never more than
an inch in length, dingy gray, with longitudinal undulations upon
the whorls, and a long, narrow anterior canal and crenulated lip.
The animal is white and yellow, and is notable for its activity.
Found from Maine to Florida, about low-tide mark.
[Illustration: /Eupleura caudata./]
On the west coast of the United States occurs a striking development
of a group of the /Muricidæ/ of a curious foliaceous appearance,
belonging to the genera /Pteronotus/, /Ocinebra/, and /Cerostoma/.
GENUS ^Pteronotus^
^P. festivus.^ The shell is marked by three well-raised varices
upon each whorl, which are reflexed backward; between each varix
is a rounded knob. All is covered with numerous spiral lines
of sculpture, which upon crossing the varices are frilled. The
aperture is oval and white within; the anterior canal is entirely
closed and is reflexed slightly over the back. Length two inches;
color dingy white. Found on the southern coast of California.
(Plate LXXII.)
GENUS ^Ocinebra^
^O. poulsoni.^ This has the same dingy white color as the species
last described. Its plan of sculpturing is somewhat different and
consists of a series of rounded varices, about nine to a whorl,
crossed by spiral lines. The anterior canal is open, and just
within the white aperture, upon the inner side of the lip, is a
series of five or six little round teeth. This species frequents
the waters near San Diego, and sometimes grows to be two inches in
length. (Plate LXXII.)
^O. lurida.^ A much smaller species than the last, being not more
than one half to three fourths of an inch in length. Very common
at Monterey and in San Francisco Bay. It is strongly marked with
spiral lines covering the longitudinal undulations usually found in
this genus, but which are less prominently developed in this case.
There are several species of small ocinebras upon the California
coast, but they are not easily determined without a more critical
examination [pg385] than we are giving our specimens. They are
^O. interfossa^, a small shell with deep spiral grooves, sharp
varices, and deep sutures; and ^O. circumtexta^, also small, but
heavy, short-spired, with scalloped or crenulated outer lip.
GENUS ^Cerostoma^
^C. nuttallii.^ A species belonging to the southern coast of
California. It may be recognized at once by two prominent
characters: first, a horn-like projection from near the base of the
outer lip, and, second, the tumid varices alternating with rounded
knobs. It has no spiral series of lines like those in /Pteronotus
festivus/; and it has a row of five or six little teeth upon the
inner side of the aperture, like those in /Ocinebra poulsoni/.
The anterior canal is closed. It is about two inches long. (Plate
LXXII.)
^C. foliatum.^ A shell somewhat like the last, but almost twice as
large, with heavy wing-like varices (three upon each whorl), made
up of overlapping plaits. The knobs between the varices are much
smaller, while the revolving ribs, though fewer in number than in
most of these west-coast murices, are heavy and large. The aperture
is oblong, the anterior canal closed. There is a "horn" near the
base of the aperture, as in /C. nuttallii/, but no row of teeth
upon the under side of the lip. The color is dingy white. (Plate
LXXII.)
In the waters of Oregon and Washington there are a few trophons and
other forms similar to the east-coast genera. These no doubt belong
to the boreal and arctic faunal provinces, and have spread over
both the Atlantic and Pacific northern regions.
SUBFAMILY ~PURPURINÆ~
This is considered a subfamily of the /Muricidæ/, and the group
therefore bears the subfamily termination /-inæ/. There is no vital
difference between it and the subfamily /Muricinæ/. The operculum in
the /Purpurinæ/ has a lateral nucleus instead of a subterminal one,
but beyond this there are no essential differences. The shell of the
purpuras is generally heavy and solid, being adapted to a life among
rocks which are exposed to the beating of the surf. There is a lack
of that extravagant sculptural design so characteristic of the true
murices, most of the purpuras being comparatively smooth, in order,
no doubt, that they may offer as little resistance as possible to the
rushing, seething waters of exposed rocky shores.
The /Purpurinæ/, like some of the murices, when mutilated, exude a
reddish-purple fluid. On account of this, the ancient Romans used to
gather great quantities of certain Mediterranean forms belonging to
these families, place them in large mortars, [pg386] and grind them
up, shell and all. A garment dipped in the mixture and then exposed
to the sun would receive a rich purple dye. This was the basis of the
famous "Tyrian purple." The process was lost, and was rediscovered
many centuries later, but it was long ago abandoned in favor of the
far superior modern chemical dyes.
GENUS ^Purpura^
[Illustration: /Purpura lapillus./]
[Illustration: The same; a younger specimen.]
^P. lapillus.^ No one who has ever spent an observant hour among
the rocks at low tide, on the shores of Massachusetts or Maine,
has failed to notice the myriads of /P. lapillus/ clinging to
the barnacle-covered boulders, or slowly creeping about in the
tide-pools. This rather pretty little mollusk is a native of Great
Britain, and there attains its greatest development and exhibits
best its marvelous range of variation. It is presumed to be an
immigrant in American waters, having found its way across the sea
by Iceland and Greenland, and thence down the coast. As it is a
cold-water animal, and can only survive in open, rocky stations,
it will probably never pass south of New York. It is difficult
to describe this well-known species because it is so extremely
variable. There is an individuality about the species which causes
it to be recognized at once, yet its details are elusive. It is
never more than one and a half inches long (in the United States),
and varies in color from white through yellow to chocolate. Often
it is banded in yellow or brown. Near the only sand-beach of Bar
Harbor is a colony with vermilion bands. The shell varies from a
smooth to an exceedingly rough exterior, the latter being caused by
raised scales along the lines of growth, which make the shell even
prickly to the touch. Of this latter form there is a large colony
on Campobello Island. Numerous coarse revolving ridges are common.
The columella is flattened and smooth, and its lower portion is
a little twisted. The anterior canal is short. /P. lapillus/ has
been accused of attacking clams and boring their shells, as does
the predaceous /Urosalpinx cinerea/, but the accusation is not well
founded. /Purpura/ is carnivorous, and no doubt destroys many young
barnacles; but with its short and small foot it would find great
difficulty in digging in the sand for clams.
In Florida waters there are several purpuras, which properly belong
to the West Indian fauna, but enjoy an extensive range.
^P. patula.^ This species has a rounded body-whorl, and sometimes a
low spire, which give it much the appearance of a large limpet. Its
back is decorated with rows of nodules in regular order, forming
a spiral series. The chief point of distinction is the deeply
excavated, broadened, and flattened columella-lip of salmon-color.
A portion of the whorl itself is worn down and made smooth by being
dragged over sharp coral rocks, revealing underneath the rough,
incrusted exterior, a transparent colorless shelly substance. Dark
and chestnut-colored [pg387] patches and spots adorn the outer
lip. The shell is from two to two and a half inches long. (Plate
LXXIII.)
^P. hæmastoma.^ Like its relative, /P. lapillus/ of Northern
waters, this species is so variable as almost to defy description.
The form that usually occurs from Hatteras to Florida is of a
bluish-gray color, and is indistinctly encircled with narrow yellow
zones, which are crossed by somewhat vague longitudinal waves of
black. The columella and outer lip and interior are orange-yellow.
The spire is moderately high, with a sharp apex. The whorls are
noduled upon the shoulder. There are revolving grooves throughout,
even within the aperture. A Texan variety of this species has
a much more elevated spire, with channeled sutures, and small
aperture of bright salmon-color.
Upon the Californian coast there are three species of /Purpura/,
which markedly resemble the /P. lapillus/ of the Maine shores.
Their extreme variability has given rise to much confusion in their
nomenclature; the multitude of names given by numerous authors to
the varietal forms of these three species constitute a list of
synonyms which is appalling to the systematic student.
^P. crispata.^ With very few modifications, a description of /P.
lapillus/ would apply to this species, which occurs commonly at San
Francisco and ranges north. /Crispata/ is possibly heavier, with a
smaller aperture, and with four or five round teeth upon the inner
white surface of the thickened outer lip. It ranges in color from
pure white to dark brown and is sometimes banded. The surface may
be smooth or rough, and is sometimes ruffled all over with wrinkled
frills. Length one and a half inches. Its habits and station are
much the same as those of /P. lapillus/, of which it is possibly
a descendant, somewhat modified by changed environment. (Plate
LXXIII.)
^P. lima.^ A less common species, with rounded whorls and channeled
suture, and about fifteen spiral grooves upon the whorls. The color
is light brown; the length from one quarter of an inch to one inch.
^P. saxicola.^ A shell exceedingly abundant along the whole
Californian coast, living under quite the same conditions as the
purpuras already described. It is smaller than the last two, being
always less than an inch in length. It also runs through the gamut
of variations as to color-scheme and sculpturing, but always
preserves a certain individuality. There is a tendency to a small
umbilicus; the outer lip is sharp; the columella is flattened and
slightly twisted; and anterior canal is short, and bears to the
left. A smaller aperture, with relatively thicker shell, seems to
be all that distinguishes it from the smaller varieties of the
east-coast species. (Plate LXXIII.)
GENUS ^Monoceras^
This genus, which is very closely allied to /Purpura/, is almost
wholly confined to the west coast of the United States. The name is
given on account of a peculiarity, which has, however, already been
noticed in /Cerostoma/, namely, a horn-like projection from the basal
portion of the outer lip. In all other respects this genus is nothing
but a true /Purpura/. [pg388]
^M. lapilloides.^ The shell in this species is about an inch in
length, and has markings which give it a striking resemblance to
granite. A row of small round denticles upon the inner surface
of the lip is a characteristic already noticed in some of the
west-coast murices. Their station is the same as that of the
purpuras—between the tides on rocky, exposed shores. (Plate
LXXIII.)
^M. engonatum.^ This species has sharply ridged whorls, and
revolving ribs with wavy growth-lines between them. In other
respects it is almost identical with the last described. It is
often found mingled with the seaweed which covers rocks between
tides, and, when moist, simulates the color of its surroundings.
(Plate LXXIII.)
GENUS ^Chorus^
^C. belcheri.^ This family cannot well be left without at least
a mention of this large and rather handsome species. /Chorus/ is
a genus of but few species, confined to the Pacific shores of
North and South America. This particular species does not reach as
far north as San Francisco, but may be taken at low tide in the
vicinity of San Diego. The prominent feature of the shell is the
posterior canal, which, being abandoned as the growth of the shell
continues, leaves a series of hollow, folded spiny processes upon
the shoulder of the body-whorl, which appear like jagged points
upon the spire. (Plate LXXIII.)
FAMILY ~COLUMBELLIDÆ~
This is a large family of small but often exceedingly beautiful
shells. Their distribution is mostly tropical, but the list of
North American species is a very generous one indeed if the
deeper-water forms are included. The animal is quite the same as in
the /Buccinidæ/, to be described later. (See also description of
/Buccinum undatum/ on page 330.) The shells are usually quite solid,
with a long, narrow slit for an aperture; the outer lip is thickened
on the inside, especially about the middle portion, and is deeply
toothed; and the lower portion of the columellar lip is also ribbed
or toothed.
GENUS ^Columbella^
^C. mercatoria.^ This Antillean species is found in Florida, and
is one of the gems among the American shallow-water shells. Its
height is about one half of an inch. It is decorated with revolving
grooves and with a variously patterned color-scheme of broken
yellow or reddish [pg389] lines on a white background, or of
white splotches on a brownish background. (Plate LXXIV.)
[Illustration: PLATE LXXIII. 1, Purpura patula. 4, Monoceras
lapilloides. 2, Purpura crispata. 5, Monoceras engonatum. 3,
Purpura saxicola, enlarged. 6, Chorus belcheri.]
[Illustration: PLATE LXXIV. 1, Columbella mercatoria, enlarged.
4, Nassa fossata, about natural size. 2, Columbella (Amphissa)
corrugata, enlarged. 5, Nassa mendica, enlarged. 3, Columbella
(Astyris) gausapata, much enlarged. 6, Nassa perpinguis, enlarged.
7, Nassa tegula, enlarged. 8, Siphonalia kellettii, reduced. 9,
Tritonidea tincta.]
^C. (Anachis) avara^, and the variety ^C. similis^. These rather
slender shells, about one half to three fifths of an inch long,
occur from Florida northward to Cape Cod. The upper whorls are
smooth, the lower ones are undulated with vertical costæ (ten
to thirteen), and the body-whorl is encircled below the middle
by a series of revolving, closely set grooves. The aperture is
typical of the genus, though less strongly marked by internal
callosity on the outer lip and with less prominent teeth than in
/C. mercatoria/. The greater development of the revolving grooves,
which spread over the entire surface of the body-whorl and cross
the costæ, producing a granulated surface, constitutes the variety
/C. similis/. The color is brownish, with white reticulations.
This species is to be found in considerable abundance in sandy mud
and among stones and algæ about low-water mark. At New Bedford and
Martha's Vineyard, and on Cape Cod, it may always be taken. It is
also common at Norfolk and along the Virginia and Georgia coasts.
^C. (Astyris) lunata.^ One of the characteristic eastern-coast
shells, which, like the last species, ranges from Cape Ann in
Massachusetts to the West Indies. It occurs about low-tide mark
and just below, upon stones and algæ, or crawling about on a soft
bottom. On account of its generic features, combined with the
peculiar coloration, the species cannot be mistaken. The latter is
a ground of reddish-brown or fawn, with encircling rows of large
white or yellowish spots. The whorls are quite smooth. Length not
over one fifth of an inch.
The collector soon learns to recognize the variable forms of
these northern-range columbellas. They are not a difficult group,
for once their generic position is established by the characters
of the aperture (which are constant) the species can readily be
determined, notwithstanding their tendencies to vary from the type.
Californian waters also have several columbellas. The conchologists
of the west coast have preferred to apply to their shells, and
indeed to employ in general use, a large number of subgeneric names
in place of the ordinarily accepted generic ones. The result of
this is to confuse at first the student of conchology, who, though
fairly familiar with the molluscan genera, finds himself perplexed
when he confronts a list of west-coast shells. Thus the two common
Californian columbellas are /"Amphissa" corrugata/ and /"Astyris"
gausapata/, these two species belonging to different subgenera of
the genus /Columbella/.
^C. corrugata.^ This shell finds its metropolis in Puget Sound,
but occurs also along the Californian shore. The aperture is wider
than is usual in this genus. The surface is deeply wrinkled by
longitudinal costæ and is encircled by revolving grooves. Length
one half of an inch; color red, or orange to light brown. It is
found in shallow protected waters. (Plate LXXIV.)
^C. gausapata.^ This species lives in great numbers about the roots
of eel-grass. It is very small and smooth, with a rather high
spire. The color of the spire is deep brown; the body-whorl is
lighter in color. Occasionally the body-whorl is obtusely carinated
just below the suture. This little shell is very common upon many
beaches after heavy winds, but it should be sought for at very low
tides and gathered alive. (Plate LXXIV.) [pg390]
FAMILY ~NASSIDÆ~
These are familiar, and often very characteristic, littoral shells in
all parts of the world. Where they exist at all they are generally
to be found in astonishingly large numbers, sometimes even crowding
out all other mollusks. They are exceedingly active and predaceous,
feeding upon other mollusks, whose shells they bore through by means
of the sharp teeth upon their lingual ribbon. The /Nassidæ/ of the
east coast find a relentless enemy in the small hermit-crabs, which
attack them, drag them from their coverings, and then proceed to
occupy the empty shells themselves; the torn and lacerated /Nassa/
animal is thereupon leisurely eaten, a retribution probably well
deserved. The animal of /Nassa/ (the principal genus of /Nassidæ/)
is peculiar in having frequently a bifurcated tail; or, to speak
more correctly, the posterior end of the foot is terminated by two
appendices. It has a long siphon, and eyes placed upon the outer
sides and near the base of the tentacles. The operculum has serrated
edges.
GENUS ^Nassa^
[Illustration:/Nassa trivittata/, showing the animal as if crawling.]
[Illustration: /Nassa trivittata./]
^N. trivittata^, ^N. obsoleta^. These are the two nassas of the
New England and New Jersey coasts. The first has a more northerly
range, extending to the Gulf of St. Lawrence; the other is not
usually found north of Cape Cod, but below that point as far as
Hatteras it is probably the commonest shell of the coast. It fairly
swarms in sheltered muddy reaches about low tide. Little pools left
by the tide on the Jersey flats are sometimes so crowded with /N.
obsoleta/ that for lack of room the animals crawl over one another.
/N. trivittata/ is more commonly taken at small depths in the
harbors, where it seems to live well upon all kinds of sea-bottom.
Probably they exist in great numbers along the southern shore of
Long Island, for the beaches are often lined with their dead and
worn shells. Over half the specimens thus found will have a little
round perforation upon some whorl, showing that they were victims
of some cannibalistic brother. The shells of the /Nassidæ/ have a
short, ovate aperture, with a short anterior canal. The inner lip
is smooth, and is usually coated over with a more or less heavy
[pg391] deposit of enamel. /N. trivittata/ is about one half to
seven tenths of an inch long, and is yellowish-white. A series of
revolving grooves cutting across a series of longitudinal lines
gives the shell a decussated or granulated appearance. The whorls
are somewhat shouldered at the sutures, and are white inside.
/N. obsoleta/ cannot be called a handsome shell by the most
enthusiastic collector. Its spire is usually eroded or completely
dissolved away. The color is blackish to olive, with the aperture
purplish-black. The columellar lip is arched, with a twist or
fold in its lower portion. It is decussated by crossing lines and
grooves, though not so conspicuously as /N. trivittata/; sutures
simple; length one half of an inch to one inch. Old specimens not
only become eroded, but are usually covered with vegetable mould,
and are not over-inspiring to the collector. They often live in
brackish water, and frequent all the inlets and marine flats
between Cape Cod and Hatteras. Below Hatteras both this and the
last-named species occur, though not so plentifully.
[Illustration: /Nassa obsoleta./]
^N. vibex.^ This ubiquitous little mollusk seems content in any
station, and swarms in all the sandy bays of Florida. It is a
busybody, always on the move, and its long siphon is constantly
vibrating. The shell is about one half an inch long and shining
white, with brown or reddish spots. There are prominent
longitudinal undulations and revolving lines upon the lower part of
the body-whorl. The anterior canal is deeply cut and very short;
the columellar lip arched, richly calloused, and often granulated
at its base. This is probably the first live shell the collector in
Florida will encounter. The animal is very graceful and prettily
marked in color. The terminal cirri on the foot form a notable
feature—a character belonging to the entire family.
[Illustration: /Nassa vibex./]
^N. fossata^, ^N. perpinguis^. On the California coast there are
the huge (for this genus) /N. fossata/ and the smaller but no less
interesting /N. perpinguis/, also ^N. tegula^ and ^N. mendica^.
/N. fossata/ grows to a length of one and a half to two inches.
When adult the lip is somewhat thickened, and the entire aperture
is bright orange. The color of the shell is ashen-gray, and it
is marked with spiral and transverse riblets which produce a
granulated surface, especially upon the upper whorls. The shell is
ribbed inside the mouth. A deep groove circles the anterior canal
at the base of the body-whorl. /N. perpinguis/ is an especially
graceful shell, smaller than the last-named and more finely
decussated and darker (brown) in color. It also has a deeply
channeled groove encircling the base of the body-whorl. It is
often banded in chestnut. Both these species occur in the southern
part of California only; /N. tegula/ and /N. mendica/ are of more
northern range. The former resembles the Floridian /N. vibex/. /N.
mendica/ is a slender shell three quarters of an inch long, with
prominent longitudinal ridges, and light brown in color, with a
white aperture. (Plate LXXIV.)
FAMILY ~BUCCINIDÆ~
From the number of subfamilies and genera included in this
exceedingly large and comprehensive family, it would almost [pg392]
seem that it has served as a sort of dumping-ground for various
groups of mollusks of uncertain biological affinities. Although the
family has recently been reduced by the removal of several large
families, it still remains a bulky one.
GENUS ^Buccinum^
The animal is described at some length on page 330. It has no
striking peculiarities. The siphon in /Buccinum/ is fairly long; the
eyes are placed about midway between the base and the end of the
tentacles. It is in general a conventional prosobranch animal. The
great majority of the members of this family have a boreal range and
are found widely distributed within the colder waters of the world.
^B. undatum.^ This is the most prominent representative of the
/Buccinidæ/ upon the North Atlantic shores of the United States.
It is an exceedingly common shell, ranging from Cape Cod to
Greenland. It is also found in England and Scotland, where it is
extensively used as food under the familiar name of "whelk." It
affects every kind of station and seems to be as much at home in
very considerable depths as about the low-tide mark. Upon the Maine
coast it may be found almost everywhere, just below low tide. If
none are in sight they may be attracted by putting a dead fish
in a basket and anchoring it near shore. The American whelk is
somewhat smaller than the British variety, although it attains a
length of full three inches. It has revolving ribs and longitudinal
oblique folds. A yellowish-brown, velvety epidermis covers the
entire shell. The lip is simple, and the shell is white or golden
yellow within. The columella is somewhat twisted; the operculum
is corneous, with a lateral nucleus. The variations in this shell
are so great as to have caused naturalists no little perplexity.
Specimens taken near large cities are apt to be defective. (Plate
I.)
[Illustration: /Buccinum undatum./]
GENUS ^Chrysodomus^
^C. decemcostatus.^ One of the most striking shells of our
northeast coast. As its name indicates, it is decorated with
(normally) ten costæ. [pg393] These are prominent revolving ribs
or keels upon the body-whorl, the upper one being the largest, the
others diminishing in size toward the base of the shell. Upon the
upper whorls but two of these circling keels appear. The lip is
plain, but somewhat modified by the termination of the ribs. The
columella is arched above; the canal produced (sometimes to the
left). The color without is dull ashen-white to horn; within, pure
white. The operculum is small, with a terminal nucleus. The animal
is the same as /Buccinum/. This species is not quite so common as
/B. undatum/, but it is often found associated with it. At Eastport
and Bar Harbor it is abundant just below low-water mark.
[Illustration: /Chrysodomus decemcostatus./]
GENUS ^Sipho^
[Illustration: /Sipho Stimpsoni./]
^S. Stimpsoni.^ One of the most graceful of the larger shells of
our eastern coast. It is almost identical with the /S. islandicus/
of northern European waters, and for a long time was considered to
be the same species. /S. Stimpsoni/ is not found south of Cape Cod,
except possibly in deep offshore stations. North of that point it
ranges to Newfoundland, but it has enjoyed the reputation of being
a rare shell and has been greatly prized by local collectors in
consequence. It is, in fact, not rare to any one who is provided
with a dredge and rope enough to enable him to use [pg394] it
effectively in from twenty to one hundred feet of water. The spire
is high and regular, with seven to eight slightly rounded whorls.
The suture is simple, and there are faint revolving grooves. The
epidermis is thick, horn-colored, and sometimes velvety; the lip
simple; and the anterior canal produced. The shell is pure white
within. The operculum is corneous, with a subterminal nucleus. The
animal is the same as /Buccinum/, but with small irregular specks
of black. This shell is found from three to five inches long.
[Illustration: /Sipho pygmæus./]
^S. pygmæus.^ This species has the same range as that of the
species just described, and often occurs associated with the young
of the latter. It may be distinguished from /S. Stimpsoni/ by the
greater number of whorls, the more prominent revolving ridges, and
the smaller aperture. The epidermis is drab-colored and strongly
corrugated, inclined to hirsute. The color of the shell is pure
white. Length one inch to one and a half inches. It is found from
low-tide mark to very considerable depths.
GENUS ^Siphonalia^
^S. kellettii.^ /Siphonalia/ is one of the Pacific genera of the
/Buccinidæ/, which finds its greatest development in Japanese
waters. One of these Japanese species, /S. kellettii/, is also
found in California. It has the typical animal of the /Buccinidæ/,
and a fusiform shell white to brownish in color, and three to five
inches in length. It is conspicuously marked upon the whorls by a
revolving series of large rounded knobs and indistinct revolving
grooves. The operculum is corneous, the nucleus subterminal. It is
found in shallow water to low-tide mark. (Plate LXXIV.)
GENUS ^Tritonidea^
^T. tincta.^ A Floridian species which ranges from Hatteras to
the West Indies, and finds its station near low-tide mark, upon
coralline rock or rough, stony bottom. It is about one inch in
length, is of a brownish horn-color, and has an oval aperture with
a crenulated outer lip and a deep anterior canal. An entering ridge
of white enamel at the top of the columellar lip forms, with one of
the teeth of the outer lip, a posterior canal. It is sculptured,
with revolving ridges and crossing longitudinal folds. The color
is bluish-white within the shell, touched with yellow about the
anterior canal and along the edge of the outer lip. (Plate LXXIV.)
FAMILY ~TURBINELLIDÆ~
GENUS /Fulgur/
Of the two genera of this family which occur in American waters,
/Fulgur/ may be taken as the most characteristic mollusk of the
American Atlantic fauna; that is to say, /Fulgur/ occurs only on
the American east coast. Its range is from Cape Cod to the West
Indies. The two Northern species are /F. carica/ and [pg395] /F.
canaliculata/, both of which are exceedingly common in sandy shore
stations from Cape Cod southward.
[Illustration: /Fulgur carica./]
^F. carica.^ The largest univalve north of Hatteras, most easily
recognized by its pear-shaped shell, with simple suture and
brilliant vermilion aperture. The anterior canal is long and
open; the columellar lip is twisted and arched, and the outer
lip is simple. There is a revolving row of nodes or spines of
various degrees of prominence upon the shoulder of the body-whorl,
continued on the spiral whorls just above the suture. The color
varies from ashen-gray to a dirty brown. In young specimens there
are stripes and bands of violaceous brown, and the shells are
striate within the aperture. The length of this shell is sometimes
nine inches.
^F. carica^ frequents almost any sort of bottom. In Long Island
Sound they are common on stony ground, but they do not attain
the maximum size and the high degree of aperture-coloration
characteristic of those taken along the New Jersey shore, on sandy
stations exposed to the surf. The string of curiously shaped
capsules containing the eggs of /Fulgur/ is shown in Plate I.
[Illustration: /Fulgur canaliculata./]
^F. canaliculata^ often occurs associated with the last. It does
not attain quite the same size, but specimens of both species
are, on the [pg396] average, about equal in cubic capacity. It
is pear-shaped, like /F. carica/, and has a long anterior canal;
but its distinguishing features are the flattened shoulder of the
whorls and the deeply channeled sutures. The epidermis is brown,
thick, and heavy. The color of the shell is whitish-gray, yellowish
within. It is found in the same places as /F. carica/, and is very
abundant at Atlantic City and along the entire New Jersey coast.
^F. perversa.^ A Floridian species, immediately recognizable by the
fact that it is sinistral; otherwise a description of the shell
would almost fit that of /F. carica/, except in the matter of the
color of the aperture, which in /F. perversa/ is brownish-white.
The brownish streaks upon the whorls, in young specimens, are
a very noticeable feature of this shell. The shoulders of the
whorls are rather flatter than in /F. carica/, but, unlike /F.
canaliculata/, the sutures are simple. The row of nodes or rounded
spines which encircles the body-whorl appears in the spire as nodes
just above the sutures. The animal is jet-black, and frequents
sandy flats, where, at low tide, it may be gathered in considerable
numbers, as it plows its way along, almost wholly concealed beneath
the sand. Large specimens measure quite a foot in length. In old
shells the color-markings are not so brilliant, the shells being a
dull, lusterless white. (Plate LXXV.)
^F. pyrum.^ Another Floridian species, much smaller than the last
(three to four inches), with a regular, pear-shaped outline, a long
anterior canal, a low spire, deeply channeled sutures, flattened
shoulders, and no spinous or nodose processes. It is ornamented
with revolving inconspicuous ribs or striæ, alternately larger,
and has a somewhat hirsute epidermis. The color is white, with
transverse broad yellowish or rusty lines; the color within the
aperture resembles that of the exterior color-lines. It is found on
sandy stations, in shallow water. (Plate LXXV.)
GENUS ^Melongena^
^M. corona.^ A Floridian species, named from the single or double
row of spinous processes upon the shoulder of the body-whorl and
the crenulated appearance of the spire caused by the continuations
of the triangular spines. The three apical whorls are not spinous.
There is also a row of hollow triangular spines obliquely
encircling the base of the shell. The epidermis is heavy, rough,
and brown; the aperture oval and large; the outer lip notched at
points where the spines commence; the anterior canal wide and
short; and the columella white and twisted, and banded within with
purplish-chestnut and white. The color without is drab in older
specimens, in young specimens chestnut banded with revolving striæ.
Length four inches. Found in shallow water. This active predaceous
animal must be the terror of the mollusks in Florida. With his
sharply toothed radula he is able to pierce even the ponderous
clam-shell, /Venus mercenaria/, variety /mortoni/, and devour the
soft fleshy parts within. No mollusk, save, perhaps, the vigorous
/Strombus pugilis/, can escape the attack of this highwayman.
(Plate LXXV.)
[Illustration: PLATE LXXV. Fulgur perversa. Melongena corona. Fulgur
pyrum.]
[Illustration: PLATE LXXVI. Fasciolaria gigantea, very much reduced.
Fasciolaria distans. Fasciolaria tulipa.]
[pg397]
FAMILY ~FASCIOLARIIDÆ~
This family comprises a number of genera of mollusks which have a
fusiform shell, with a long-drawn-out spire and a long anterior
canal. The animal is in no manner remarkable; no essential
differences are to be noted from the usual conventional type of
gasteropod mollusk, represented in the two families last described.
GENUS ^Fasciolaria^
This genus is of tropical range, and contains many species of shells
which are more or less conspicuous for their large size or their
beauty of form. Three species occur in Floridian waters, and all
of them may be taken about low-tide mark on the sandy flats which
are so characteristic of Florida bays and harbors. All of them are
sluggish animals which crawl very slowly along the bottom or bury
themselves almost wholly in the sand, leaving only the tip of the
spire projecting slightly above.
^F. gigantea.^ This is said to be the largest gasteropod shell
known. It often attains a length of sixteen inches, and specimens
are reported to have been found measuring no less than two feet.
This huge mollusk has a symmetrically fusiform shell, with whorls
obtusely ridged and armed with large rounded nodes. The aperture
is reddish-brown within. The anterior canal is long and open, and
there are three "plaits," or folds, about the columella. The outer
lip is more or less sinuate, the color is fleshy-white, and the
shell is covered with a thick yellowish or chestnut epidermis. The
animal is of a brilliant scarlet color. (Plate LXXVI.)
^F. tulipa.^ An exceedingly common species of Floridian waters,
which may justly be classed among the "show shells" of the American
Atlantic fauna. It has a typically symmetrical, fusiform shape,
with gracefully rounded whorls, and is spirally but not deeply
grooved. The sutures are crenulated; the anterior canal is long;
there are three entering folds upon the columella; and the outer
lip is simple. The scheme of coloration is variable, but there are
two chief patterns, which are usually followed, though they often
are considerably modified. One is a light-bluish body, variegated
with chestnut or olive blotches, which are more extensive upon
the spire than upon the body-whorl; the other is a pinkish body,
encircled with revolving black lines. The specimens of /F. tulipa/,
which are found so abundantly in the shallow bays and estuaries of
the Florida coast, are, for some reason, never brightly colored, as
are those taken in the open sea. The length is about four to six
inches. (Plate LXXVI.)
^F. distans.^ A form almost identical with that last described. It
is much smaller, varying from two to three inches in length, lacks
the crenulations of the sutures, and is perfectly smooth, save for
a few spiral ridges about the base. The color is bluish-white, with
clouded longitudinal [pg398] streaks of olive. Encircling the
shell are from four to seven black lines. (Plate LXXVI.)
These three species of /Fasciolaria/ often occur associated upon
sand-banks which are exposed at unusually low tides. It requires
some force to dislodge the large /F. gigantea/ from its bed of
sand. When the apex is discovered projecting an inch or less from
the bottom, the collector must scrape away the sand down to the
body-whorl, and then secure a good hold upon the spire and pull
hard. The stupid animal will not at once withdraw into his shell,
but will hang protruded from the aperture like a great piece of
vividly red meat. To extract any of these larger fasciolarias from
its shell, it is necessary to boil it for ten or fifteen minutes.
Large specimens of /F. gigantea/ should remain in the pot half an
hour. The heavy corneous epidermis of /F. gigantea/ will dry and
crumble away unless it is rubbed with vaseline about once a year.
FAMILY ~VOLUTIDÆ~
GENUS ^Voluta^
[Illustration: /Voluta junonia./]
The =Volutidæ=, like the cowries, are "aristocratic" shells. As was
stated above, there are many collectors who have become so fascinated
by the shells of a few of these "first families of the /Mollusca/"
that they make great efforts and spend no small sums in seeking to
complete their cabinet series of the rare and more beautiful forms.
The /Volutidæ/ certainly have very beautiful shells, and they are for
the most part exceedingly rare. The reason of their rarity has no
doubt something to do with their habits. They are probably largely
dwellers upon rocky ground, where the dredge cannot reach them.
There is but one species of /Voluta/ upon the American coasts which
is available to the shore-collector, and this is the well-known and
much-sought-after ^V. junonia^. The animal of /Voluta/ has a very
broad foot, and a head curiously divided into two lobes, upon which
are placed sessile eyes. A remarkable feature of the genus is the
lack of an operculum. [pg399]
^V. junonia.^ This volute has never been taken alive in shallow
water near the shore, but is occasionally found cast upon the
beach after violent storms. Sanibel Island is the best locality.
/V. junonia/ has an obtuse apex, a long aperture, and a shell
from three to three and a half inches in length. The color is
cream-white, painted with rows of large deep-red spots. In his
"American Marine Shells," published nearly thirty years ago, Mr.
Tryon says: "This is the most rare and valuable American marine
shell; specimens in good condition sell for from fifty to one
hundred dollars." A good specimen is probably not worth so much
to-day as when Mr. Tryon wrote, but it is at least worth a careful
survey of a Floridian beach after a storm.
FAMILY ~MARGINELLIDÆ~
GENUS ^Marginella^
This is a family of exquisite little shells. In point of beauty they
would rival the volutes were they not so much handicapped by their
small size. The largest /Marginella/ is not more than an inch and a
half in length, while the great majority of its two hundred tropical
species do not exceed one half an inch. The animal is very similar
to that of /Voluta/; indeed, the marginellas were until recently
included in the /Volutidæ/. The shell is also suggestive of /Voluta/.
It is porcelanous, highly polished, and shining like all shells
which are covered by a portion of the mantle when the animal is
extended. Forty-seven species of /Marginella/ are recorded from the
Atlantic coast of the United States. The marginellas frequent sandy
or muddy sheltered spots, and may be collected between tide-marks.
In California there are several species, which are so minute that it
seems hardly worth while to attempt a description of them. They are
white and very inconspicuous little shells. One is tempted, however,
to speak of some of the fine marginellas of the Bahamas. The animals
are quite as beautifully marked as the shells themselves, while the
shell of one species is used in jewelry on account of its pearly
luster suffused with the most delicate pink.
^M. apicina.^ The most abundant Floridian species of this genus. It
is not more than one third of an inch long, with a depressed spire,
a large body-whorl, a long aperture nearly equaling the entire
length of the shell, a thickened outer lip, and four very prominent
plaits on the columella. The surface is smooth. The white, enlarged
outer lip is glazed or highly polished, and bluish or brown in
color, with red spots. (Plate LXXVII.) [pg400]
FAMILY ~OLIVIDÆ~
GENUS ^Oliva^
The genus /Oliva/ is one of the favorites among collectors. It
comprises smooth, highly polished, porcelanous, and oval shells
with a deeply notched, long, narrow aperture. The columellar lip is
usually heavily calloused and ornamented with oblique folds. The
animal's foot is very large, and extends laterally into lobes which
curve back over the shell. In front the propodium is very large,
forming, as in /Natica/ and /Polynices/, a sort of plow. The mantle
lobes almost cover the shell when extended.
^O. literata.^ The only American example out of some sixty known
species. It is found in great abundance in sandy tide-pools along
the west Florida shores. It ranges from Hatteras to the West
Indies, and may be looked for in stations similar to those of the
naticas. It is exceedingly active, crawling rapidly over the sand
or burying itself very quickly out of sight, and is carnivorous.
The shell is highly polished, about two inches long, and pale
yellowish-white in color, covered with longitudinal, angulated,
or zigzag lines of chestnut. The spire is short, the sutures
channeled, and the columella calloused with white enamel, and
obliquely striated. (Plate LXXVII.)
GENUS ^Olivella^
The genus /Olivella/ resembles /Oliva/ very closely in conchological
characters, but the shells are, with few exceptions, exceedingly
small, and usually have a somewhat more elongated spire than is the
case in the genus /Oliva/ proper. The animal of /Olivella/ seems to
be a degenerate, for it possesses neither tentacles nor eyes. In
habit and station it resembles /Oliva/.
^O. mutica.^ In Floridian waters this species is exceedingly
common. It is not more than one fifth of an inch long, is highly
polished and shining, and yellowish-white in color, with revolving
pale rufous bands. It has the typical oliva-shape.
[Illustration: PLATE LXXVII. 1, Marginella apicina, enlarged.
3, Olivella biplicata, enlarged. 2, Oliva literata. 4, Conus
floridanus. 5, Cancellaria reticulata.]
^O. biplicata.^ A Californian species of considerable interest, the
largest of the olivellas. It was evidently used by the aborigines
as wampum or as ornaments, for a great many specimens are found
among buried Indian relics. This species is about the size and
shape of an olive. The spire is short, though longer than the
typical /Oliva/ spire, the shell is smooth and highly polished, and
the columella is thickly calloused, and has two entering folds near
the base. The color is creamy-white to dove-color, with a purple
sheen over all, and purple markings [pg401] about the base.
Professor Keep speaks of the vast numbers of these olivellas on
sandy stations along the Pacific coast. Having found a place where
a "little stream of water was oozing out from the bank of sand,"
he proceeded to dig with a hoe. "I found them [/O. biplicata/] by
the hundreds," he continues, "and I had gathered about a thousand
before the tide came in. They seemed to lie in groups just under
the surface of the sand, yet wholly concealed from sight." (Plate
LXXVII.)
^O. boetica.^ A much smaller Pacific form, with a higher tapering
spire. It is brown to bluish in color, and often has yellowish
stripes. It is polished and shining. Found in sandy stations.
FAMILY ~CONIDÆ~
GENUS ^Conus^
This is a comprehensive family of several highly diversified genera.
Its most prominent genus is /Conus/, a name which indicates the
principal feature of the shell, for it is almost an exact cone in
shape. /Conus/, along with /Voluta/ and /Cypræa/, is entitled to the
honor of being considered an aristocrat among mollusks. There are
about three hundred and fifty species known, mostly tropical and
Indo-Pacific in distribution. The shells have many points of beauty
and are often of very high coloration and eccentric markings. Some of
the rarer forms are famous in conchological annals for the enormous
prices which they have commanded. The rare and beautiful /Conus
gloria-maris/ once brought £43 ($215) at an auction sale in London.
In all shells of /Conus/ there is a notch at the upper edge of the
aperture for the accommodation of a posterior canal. In some other
genera of this family this notch becomes a more prominent feature.
The animal has a well-developed foot, a retractile proboscis, eyes
situated upon the tentacles, and a fairly long siphon. Upon the
under surface of the foot is a conspicuous pore, which opens into a
water-vascular system of the foot. /Conus/ is accused of having a
poison-gland connected with the radula and of having shown vicious
traits when captured. The animals are shy, and remain most of the
time in hiding, while their pretty shells during life are generally
rendered obscure by a dull, colorless epidermis. There are but few
species of /Conus/ upon the Atlantic shores of the United States, and
these are confined to the warmer waters of Florida and the Gulf of
Mexico. [pg402]
^C. floridanus.^ A not unusual shell in shallow-water stations
throughout the Florida coast. It has almost the exact outlines of
a cone. The flattened shoulder is marked off by an acute carina;
the spire is low, but many-whorled and pagoda-like; the aperture is
long and narrow, and the lip is simple. The coloring is yellowish,
banded on a creamy-white background, or dotted in circular rows.
Length two inches. (Plate LXXVII.)
^C. pealii.^ One of the smallest species of this genus, its length
never exceeding one half of an inch, whereas the majority of the
cones are over two inches in length, and many of them rank as large
shells. This little Floridian species is regularly cone-shaped,
with carinated whorls, thin outer lip, and pagoda-like, low spire.
The color is reddish-brown with sky-blue spots, or bluish-brown
with lighter spots. There are encircling grooves about the base of
the shell.
FAMILY ~CANCELLARIIDÆ~
GENUS ^Cancellaria^
The last family of the /Gasteropoda/ to be considered is the
/Cancellariidæ/, which has but one genus, ^Cancellaria^. There are
several species upon the east coast belonging to deeper-water zones,
but one well-known species, ^C. reticulata^, is very common on shore
stations from Hatteras south. The shell is oblong and solid, with a
moderate spire, and whorls slightly flattened below the sutures, and
is very roughly granulated or reticulated. The aperture is narrowly
ovate, and is ribbed inside. The columella has two very strong and
prominent plaits. The color is white, banded and variegated with
reddish-brown. Length an inch or more. (Plate LXXVII.)
CLASS =SCAPHOPODA=
FAMILY ~DENTALIDÆ~
[Illustration: /Entalis striolata./]
In nearly all collections of shells from the northeast coast of the
United States are certain specimens about one to one and a half
inches long, pure white, and shaped very much like an elephant's
tusk. They are round, hollow tubes, slightly curved, of larger
diameter at one end than at the other, and with an opening at either
end. There are two very common species of these tooth shells upon
the New England coast, [pg403] ^Dentalium dentale^ and ^Entalis
striolata^. The first has a simple round hole at the smaller end of
the shell, and is faintly marked by longitudinal striæ; the other is
a smooth shell which has a notch-like fissure on the margin of the
apical perforation. Neither of these species is, strictly speaking, a
littoral form, for all the /Dentalidæ/ range into deep water, many of
them living only in the profounder depths of the ocean. But these two
species are exceedingly common in the New England coastal waters, at
very moderate depths, and may sometimes be found upon the beach cast
up by storms. They live buried in the mud, and feed upon infusorians
and all manner of microscopic organisms.
Upon the west coast ^Dentalium pretiosum^ is very abundant north of
California. It is almost like the east-coast /Dentalium/, but is more
slender. The Indians used to gather these shells and string them
together upon long threads to be carried about and used as money.
In California occurs ^Dentalium hexagonum^, a very delicate little
species with a slightly angulated shell.
[Illustration: /Dentalium/, as seen in longitudinal section (except
the foot): /S/, shell; /Mt/, mantle; /Sm/, shell muscle; /Mh/,
mantle-cavity; /F/, foot; /Mk/, cephalic prominence or oral cone;
/T/, captacula; /R/, radula; /D/, intestine; /L/, liver; /Af/, anus;
/G/, cerebral ganglion; /N/, kidney; /Ge/, generative gland.]
The animal of the /Dentalidæ/ is remarkable, and easily merits the
rank of a separate molluscan class. It has no head, no tentacles,
no eyes, no heart, and no gills. It is a mollusk because it has a
mantle, a foot, and a radula. Its position, therefore, is between the
/Gasteropoda/, which it resembles in its univalve shell and radula,
and the /Pelecypoda/, to which it is related by the pointed foot and
the absence of head and tentacles, and also by the symmetry which
pervades its organization.
Upon either side of the mouth, just beneath the flap of the mantle,
are bunches of ciliated, contractile filaments (/captacula/),
flattened at the end, which are supposed to be breathing-organs, and
are perhaps exserted for the purpose of catching food. [pg404]
The entire absence of such important organs as the heart and gills,
together with the fact that they are undoubted mollusks, would
indicate that the /Scaphopoda/ are very degenerate animals. The
circulatory and respiratory system of mollusks is typically of a high
order.
A great many specimens of the /Dentalidæ/ dredged in New England
waters are dead shells, occupied by a worm which seals up the larger
opening, leaving only a small aperture through which it protrudes its
long white body. These must not mislead the collector into a vain
search for a mantle and other molluscan characteristics of anatomy.
Some of the larger species of /Dentalium/ from deep-sea stations are
four to five inches in length. [pg405]
TABLE OF THE COMMONER NORTH AMERICAN PELECYPODS DESCRIBED IN THIS
CHAPTER
Class =PELECYPODA=
Order =PROTOBRANCHIATA=
Families Genera Species
NUCULIDÆ ^Nucula^ ^N. proxima^
^Leda^ ^L. tenuisulcata^
^Yoldia^ ^Y. limatula^
^Y. thraciæformis^
^Y. sapotilla^
SOLENOMYIDÆ ^Solenomya^ ^S. velum^
^S. borealis^
Order =FILIBRANCHIATA=
ANOMIIDÆ ^Anomia^ ^A. simplex^
^A. aculeata^
^A. lampe^
^Placunanomia^ ^P. macrochisma^
ARCIDÆ ^Arca^ ^A. ponderosa^
^A. noæ^
^A. pexata^
MYTILIDÆ ^Mytilus^ ^M. edulis^
^M. hamatus^
^M. californicus^
^Modiola^ ^M. modiolus^
^M. plicatula^
^M. tulipa^
^M. recta^
Order =PSEUDOLAMELLIBRANCHIATA=
AVICULIDÆ ^Avicula^ ^A. atlantica^
^Pinna^ ^P. muricata^
^P. seminuda^
^Perna^ ^P. ephippium^
OSTREIDÆ ^Ostrea^ ^O. virginica^
^O. frons^
^O. lurida^
PECTINIDÆ ^Pecten^ ^P. magellanicus^
^P. irradians^
^P. dislocatus^
^P. islandicus^
^P. æquisulcatus^
^P. hastatus^
Order =EULAMELLIBRANCHIATA=
CARDITIDÆ ^Cardita^ ^C. borealis^
^C. floridana^
ASTARTIDÆ ^Astarte^ ^A. castanea^
^A. undata^
CYPRINIDÆ ^Arctica^ ^A. islandica^
LUCINIDÆ ^Lucina^ ^L. tigrina^
^L. floridana^
^L. pennsylvanica^
^L. dentata^
^L. californica^
^L. nuttallii^
^Loripes^ ^L. edentula^
TELLINIDÆ ^Tellina^ ^T. radiata^
^T. alternata^
^T. bodegensis^
^T. tenera^
^Macoma^ ^M. secta^
^M. nasuta^
^M. baltica^
^M. proxima^
^M. tenta^
DONACIDÆ ^Donax^ ^D. variabilis^
^D. californicus^
MACTRIDÆ ^Mactra^ ^M. solidissima^
^M. similis^
^M. ovalis^
^M. lateralis^
^Rœta^ ^R. canaliculata^
VENERIDÆ ^Venus^ ^V. mercenaria^
Var. ^mortoni^
^V. cancellata^
^Cytherea^ ^C. (Callista) gigantea^
^C. (Callista) maculata^
^Dosinia^ ^D. discus^
^D. elegans^
^Tivela^ ^T. crassatelloides^
^Tapes^ ^T. staminea^
^T. laciniata^
^Chione^ ^C. succincta^
^C. fluctifraga^
^C. simillima^
^Saxidomus^ ^S. nuttallii^
PETRICOLIDÆ ^Petricola^ ^P. pholadiformis^
^P. carditoides^
CARDIIDÆ ^Cardium^ ^C. magnum^
^C. isocardia^
^C. lævigatum^
^C. serratum^
^C. mortoni^
^C. substriatum^
^C. corbis^
^C. quadrigenarium^
^C. elatum^
^C. islandicum^
^C. pinnulatum^
MYIDÆ ^Mya^ ^M. arenaria^
SOLENIDÆ ^Ensis^ ^E. directus^
^Solen^ ^S. viridis^
^S. sicarius^
^S. rosaceus^
^Tagelus^ ^T. gibbus^
GLYCIMERIDÆ ^Glycimeris^ ^G. generosa^
PHOLADIDÆ ^Pholas^ ^P. costata^
^P. truncata^
^P. californica^
^Zirphœa^ ^Z. crispata^
TEREDINIDÆ ^Teredo^ ^T. navalis^
PANDORIDÆ ^Pandora^ ^P. trilineata^
[pg408]
[Illustration: Anatomy of a pelecypod, /Anodonta cygnea/. The animal
with most of the left mantle lobe removed. /a/, excretory opening;
/a. ad./, anterior adductor muscle; /a. r./, anterior retractor
muscle; /au./, left auricle; /d. p. a./, dorsal pallial aperture;
/ex. sph./, exhalant siphon; /ft./, foot; /in. sph./, inhalant
siphon; /kd./, kidney; /l. ext. gl./, left external gill; /l. ext.
plp./, left external labial palp; /l. int. gl./, left internal gill;
/l. int. plp./, left internal labial palp; /l. m./, cut edge of left
mantle lobe; /mth./, mouth; /p. ad./, posterior adductor muscle;
/pc./, pericardium; /p. r./, posterior retractor muscle; /prc./,
protractor muscle; /rct./, rectum; /r. m./, right mantle lobe; /v/,
ventricle; /v. m./, visceral mass.]
[Illustration: Anatomy of a pelecypod, /Anodonta cygnea/.
Dissection from the left side. /a/, excretory opening; /a. ad./,
anterior adductor muscle; /a. ao./, anterior aorta; /a. v. ap./,
auriculo-ventricular aperture; /bl./, urinary bladder; /c. pl. gn./,
cerebropleural ganglion; /d. d./, duct of digestive gland; /d.
gl./, digestive gland; /d. p. a./, dorsal pallial aperture; /ex.
sph./, exhalant siphon; /ft./, foot; /g. ap./, genital aperture;
/gon./, gonad; /gul./, gullet; /i. l. j./, interlamellar junction;
/in. sph./, inhalant siphon; /int./, intestine; /kd./, kidney; /m/,
mantle; /mth./, mouth; /p. ao./, posterior aorta; /p. ad./, posterior
adductor muscle; /pc./, pericardium; /pd. gn./, pedal ganglion; /r.
ap./, renal aperture; /r. au./, right auricle; /rct./, rectum; /r. p.
a./, reno-pericardial aperture; /st./, stomach; /ty./, typhlosole;
/v./, ventricle; /v. gn./, visceral ganglion; /w. t./, water-tubes.]
[pg409]
CLASS =PELECYPODA=
This is a large and important class of the /Mollusca/, comprising an
extensive group of animals, which vary widely in structure. Next to
the /Gasteropoda/, it is the largest class of the phylum in number
of genera and species. The name indicates a "hatchet-shaped" foot,
but in many cases it is a misnomer. /Acephala/, meaning "without a
head," is also employed for this class, and is, perhaps, a better
term. /Lamellibranchiata/, referring to the type of gills prevalent
throughout the division, is another name often used. The popular
name "bivalves" is an altogether correct one, for all the animals
of this class have two shells. To the /Pelecypoda/ belong the
oysters, clams, scallops, mussels, and, in short, all the /bivalve/
mollusks (the word "valve" meaning "shell"). The organization of a
pelecypod is entirely similar to that of a gasteropod or a chiton
in its fundamental or essential plan, but it differs widely from
both in matters of detail. If the student will keep in mind the
general principles of gasteropod or the amphineuran structure when
he dissects his first pelecypod, he will quickly see that the latter
is about the same as a chiton would be were it folded over from a
longitudinal median line as axis along its back, so that the opposite
mantle-edges would meet, and its various shell-plates would unite
upon either side into a single valve; or it is very like a gasteropod
made symmetrical, and covered upon its two sides by separate shells
instead of covered over its top by one shell. The loss of head,
eyes, and tentacles, the substitution of labial palps, the extension
and greater development of the gills, the modification of the foot
and mantle, and the presence of certain special glands in the
/Pelecypoda/ become mere matters of anatomical detail. [pg410]
Any large clam will serve for dissection. In the neighborhood of
New York the edible species known as the "Little Neck" clam (/Venus
mercenaria/), or the larger /Mactra/ of the sandy shores, will
answer the purpose very well. In Florida, /Callista/, /Venus/, and
/Cardium/ are all available. On the west coast the large, heavy
/Tivela crassatelloides/ is probably the best subject. The oyster
(/Ostrea/) is a degenerate type; and the scallops (/Pecten/) and the
mussels (/Mytilus/ and /Modiola/) have certain special modifications
of their organs which might prove confusing, so these genera are not
recommended for dissection and study at first.
Boiling is apt to shrivel and distort the soft, fleshy animal of
the bivalves, and it is far better to examine a fresh specimen. The
surest way of opening a clam without injuring the animal is to break
one of the shells by sharp taps of a hammer, using great care not
to lacerate the body within by a too vigorous assault. Pick off the
broken pieces after having separated them carefully with a knife from
the mantle margin, to which they cling, and after having cut through
the tough adductor muscles as close to the shell as possible. The
subject for anatomical study is then prepared "upon the half-shell."
THE MANTLE
The mantle is generally very thin, often a fleshy film of the finest
tissue, and adheres to the inner side of each valve. The outer rim
of the mantle is thickened and free, i.e., is not attached to the
shell. This free portion is capable of slight extension beyond the
margin of the shell when the valves are opened and the animal is off
guard. In many genera the mantle edge is highly ornate, being waved,
crenulated, or fluted, or is beset with several rows of papillæ, and
is often richly colored. Mr. Hickson, a naturalist, who traveled in
Celebes, says that the brilliant coloring of the mantle margins of
mollusks contributed largely to the extraordinary color-effects upon
the coral reefs.
It will be seen that the mantle entirely incloses the animal at the
back and sides, just as the cover of a book incloses the pages or
printed portion. At the posterior end of the animal there is usually
a point—or perhaps two points—at which the flaps of [pg411] the
mantle lobes unite in order to form two openings. These openings are
called the siphons.
[Illustration: 1, /Solecurtus strigillatus/, showing partly united
siphons covered with leathery integument: /s. af./, incurrent siphon;
/s. ef./, excurrent siphon; /SS/, the two uniting. 2, /Cardium
edule/, showing partly united siphons with papillaceous orifices:
/A/, excurrent; /B/, incurrent siphon; /F/, foot. 3, /Scrobicularia
piperata/, in its natural position in the sand, showing very long
tubular siphons: /A/, excurrent siphon; /B/, incurrent siphon.]
SIPHONS
In some cases the mantle lobes do not actually unite to form regular
siphonal openings, but in life the free mantle-edges have a way
of adjusting themselves posteriorly to form /functional siphons/
without actually coalescing. Usually, however, the mantle flaps
not only unite posteriorly to form true siphons, but are capable
at that point of varying degrees of protrusion from the shell, and
when extended the siphons appear as two tubes. In some genera these
siphonal tubes are very long; in others they are fastened together
and surrounded by a tough, leathery integument, [pg412] which, like
the siphons proper, is only an extended portion of the mantle-edge.
The orifices of the siphons are generally papillaceous. These two
siphons (for there are always two if there are any at all) are the
/anal/ or excurrent (upper) and the /branchial/ or incurrent siphon.
The function of the latter is to draw in the pure water to bathe the
gills and to furnish food, while the office of the former is to eject
waste materials and the water which has already passed over the gills.
[Illustration: Diagram illustrating the various degrees of union of
the mantle lobes: A, mantle completely open; B, rudiments of siphons,
mantle still completely open; C, mantle closed at one point; D,
mantle closed at two points, with complete formation of siphonal
apertures; E, development of siphons, ventral closure more extended;
F, mantle closed at three points, with fourth orifice; /f/, foot; /s.
a./, /s. b./, anal and branchial siphons; 1, 2, 3, first, second, and
third points of closure of mantle; /b. o./, byssal aperture.]
MANTLE FUSION
Besides the points of juncture where the mantle-edges unite to form
the siphons, the coalescence of the two mantle lobes may be extended,
and they may become further united and fused together at other
points. Indeed, the fusion of the mantle-edges may become almost
complete; but it always leaves the siphonal openings and a third
opening through which the foot may be extended. This opening for
the foot is called the /pedal opening/, or orifice. In such cases,
therefore, the mantle becomes much like a bag or sac. The degree of
fusion of the mantle-edges appears to correspond closely with certain
changes in the organization of the animal, and this feature must be
regarded as a very important character. [pg413]
The figures on pages 411, 412, and 413 show the degrees of mantle
fusion in various groups from the open to the almost wholly closed
types. One (A, page 413) gives an example of very large siphons
united together and protected by the tough, leathery integument. To
the right of this cut may be seen the foot projecting from the pedal
opening in the mantle. Another gives the two siphons of /Cardium/,
the lower or branchial one being the longer. The mantle-edges below
are fluted, and a large foot projects forward. Another shows two
siphons of /Scrobicularia/, of the free and greatly extended type.
Fig. B (page 413) illustrates the ventral portion of a pelecypod,
which shows very well the most advanced type of mantle fusion.
Besides the siphonal openings at the end of the long projection to
the left, the only other opening is the very small orifice marked
"2," for the accommodation of a small, insignificant foot. In the
other figures different degrees of mantle fusion are indicated.
[Illustration: A: 1, incurrent siphon; 2, excurrent siphon; 3, foot.
B: 1, siphons; 2, pedal opening.]
Before removing the mantle from one side of the specimen to be
examined, note the two strong muscles which are at either end of the
body. These are the /anterior/ and /posterior adductor/ muscles,
their office being to hold the valves tightly shut. They are of great
strength, as any one may prove to his satisfaction by attempting
to open a clam. Through a long series of forms these two muscles
approach each other in position, and in the scallops and the oysters
there is but one adductor muscle, occupying a central position.
Morphologically it is the survival of the posterior adductor.
THE BRANCHIÆ OR GILLS
Removing carefully the thin, fleshy mantle, the gills are exposed
to view—that is, of course, the gills of that side of the [pg414]
animal, for there are two sets, one upon each side of the body, or
visceral mass, and lying between the body proper and the mantle
folds. Each set consists of two plate-like bodies with a texture of
reticulated or basketwork appearance. Thus there are the inner and
outer right gills and the inner and outer left gills. If one gill is
removed and carefully examined it will itself probably be found to
be double, consisting of many filaments placed side by side and then
doubled back like a row of hairpins, the filaments being united by
interciliary processes, or by vascular channels together with more or
less dense connective tissue.
The modifications of the pelecypod gills are difficult to follow,
but the principle upon which they perform their duties is the same
in all cases. The gill-filaments are all connected with a long vein,
and, being hollow, admit the blood, which is aërated by close contact
with the water and is then returned to another vein in immediate
connection with the auricles of the heart. There is another function
accomplished by the gills, which in some families seems to be quite
as important as their respiratory one, namely, the office of giving
lodgment to the ova while in process of development before hatching.
At certain seasons the gills of a number of pelecypod genera become
literally filled with eggs; sometimes this curious phenomenon extends
to the mantle itself, and more or less to the entire surface of the
animal. The eggs are first regularly ejected from the genital ducts
and find lodgment upon the body-surface, but usually only upon the
gills, where they remain as in a brood-pouch between the lamellæ of
the inner and outer gills. When the eggs hatch, the free-swimming
young escape from the mantle cavity. Probably not more than one
individual in a million ever reaches maturity.
The figure on page 408 shows the mantle removed, exhibiting the
gills, the foot, the labial palps, and the pericardium, inside of
which is the heart. Removing the gills, we find exposed the body, or
visceral mass, which, as in the /Gasteropoda/, is thickened below
into the foot. A longitudinal section is shown on page 408, the
visceral mass being sliced almost through the middle; a portion of
the gills of the farther side shows below. [pg415]
THE FOOT
The foot undergoes great variation, from a strong, powerful organ
capable of forcing its way through heavy gravelly bottom or burrowing
deeply into the sand or mud, to the merest trace of a pedal organ.
In the oyster the foot has become almost entirely atrophied; the
stationary life led by the animal renders such an organ quite
unnecessary. Excepting in a few families, the pelecypod foot is
well developed. In a number of genera the foot contains a gland
for the secretion of long silk-like or horn-like fibers, which
are collectively called a /byssus/. The use of a byssus is for
attachment to any object to effect a temporary or permanent lodgment.
The accompanying cut shows /Mytilus edulis/, a common east-coast
pelecypod, attached by its byssus to a piece of wood. Most bivalves
having a strong byssus exhibit a feeble development of the foot;
nearly all bivalves, however, show traces, sometimes only in the
embryo, of a byssal gland.
[Illustration: /Mytilus edulis/, attached by its byssus (/By/) to a
piece of wood: /F/, foot; /S/, excurrent siphon, the branchial siphon
being below it and not closed.]
[Illustration: /Pecten opercularis/, showing the ocelli, or eyes, on
the two edges of the mantle.]
The visceral mass contains the liver, the exceedingly large
generative glands, the kidneys, etc., and through all this soft
whitish or reddish mass the alimentary canal wanders about in a
tortuous fashion, finally passing through the pericardium and the
ventricle of the heart, and terminating just over and back of the
posterior adductor muscle. [pg416]
The pelecypods have no head or tentacles, but the place of the latter
is taken by two pairs of triangular flaps upon either side of the
mouth. These are called the /labial palps/, and they no doubt operate
by means of their ciliated surface to keep in motion the current of
water over the gills and to the mouth.
As a rule, pelecypods have no eyes, but when eyes are present they
are situated upon the edge of the mantle. The eyes are not highly
developed organs, but they nevertheless appear to be very sensitive
to light, for the bivalves which are so endowed will, when kept in
aquaria, instantly close their shells when the shadow of a fish
passes over them.
The heart lies in the pericardium and is situated dorsally, just in
front of the posterior adductor muscle. It has a median ventricle
and two lateral auricles, each connected with the branchiæ upon
its respective side. It seems a curious economy that passes the
intestine through the ventricle, but this is the case in the great
majority of pelecypod genera. The vascular system is closed and
is of a high order. It is probable that "breathing" takes place
upon the inner mantle surfaces as well as in the gills themselves;
for these surfaces are crowded with excessively fine and delicate
capillaries, which bring the blood very near to the water. This power
of "breathing by the skin" is quite characteristic of the /Mollusca/
in general.
Having once familiarized one's self with the more prominent features
of pelecypod organization, it becomes very interesting to examine
anatomically every new form that is captured. Surprises are always in
store, and sometimes the peculiar juxtaposition and relative sizes of
the organs are a trifle confusing; but, upon the whole, the bivalve
organization is simple and lends itself far more readily than does
that of the gasteropods to satisfactory examination. Some of the more
striking anatomical peculiarities are reserved for mention in the
notes upon the various genera and species common upon our shores.
THE PELECYPOD SHELL
As has been seen, the testaceous covering of the /Pelecypoda/
consists of two valves or shells which fit more or less closely
and [pg417] firmly together and are placed one upon either side of
the animal. The two valves are always held together tightly along a
dorsal margin by a "hinge ligament," an exceedingly tough, leathery
substance, and they are usually secured the more firmly by a system
of interlocking teeth, which project from the hinge. The opening and
shutting of the valves is controlled by the adductor muscles of the
animal, by the /ligament/ which binds the valves together, and by
the /cartilage/, an elastic pad of rubber-like appearance which is
lodged just within the hinge, and is compressed when the valves are
closed together. Thus, when the valves are closed, there is always a
strain upon the adductor to overcome the elastic resistance of the
cartilage. When a pelecypod dies and the pull of the adductor muscles
is released, the valves gape open.
[Illustration: The interior characteristics of a pelecypod shell.
Left valve of /Venus gnidia/: /A/, anterior, /B/, posterior, /C/,
dorsal, /D/, ventral margin; /AB/, length, /CD/, breadth of shell;
/a. m./, anterior, /p. m./, posterior impressions of adductor muscle;
/p/, pallial line; /p. s./, pallial sinus; /l/, ligament; /lu./,
lunule; /u/, umbo; /c/, cardinal teeth; /a. l./, anterior lateral
tooth; /p. l./, posterior lateral tooth.]
The summit or apex of the valve is called the /umbo/, or /beak/. It
is usually twisted to some extent, and in certain forms develops a
suggestive spiral figure. The beaks of the valves are the points
where the shell-growth begins, the secretion of calcareous matter
being made by the mantle margin and deposited about the edges of the
valves; the growth is therefore constantly away from the umbones.
The umbones usually point forward. In many species they touch each
other over the hinge-margin or approximate very closely; in other
species the hinge-margin is very wide and the beaks are comparatively
far apart. The hinge-margin, lying adjacent to the umbones, is known
as the /dorsal margin/ of the shell, in contradistinction to the
/ventral margin/, opposite the umbones. The /anterior margin/ is the
front edge and the /posterior margin/ the hinder edge of the shells,
through which the siphons may project.
When the umbones are about central in respect to the posterior
[pg418] and anterior margins, the shells are said to be
/equilateral/. When the two valves are almost exactly alike in size
and shape they are called /equivalve/.
In many forms there is a heart-shaped space upon the dorsal margin
of the closed valves forward of the umbones, called the /lunule/.
Similarly placed back of the umbones is sometimes a more or less
clearly defined space called the /escutcheon/. The outer surface
of bivalve shells admits of infinite variety of sculpturing and
ornamentation, ranging from a perfectly smooth to a heavily ribbed,
nodose, spinous, or deeply decussated surface. The color-markings are
often brilliant and eccentric.
The right and left valves may be distinguished by remembering that
the siphons are always posterior, and that the umbones usually point
forward.
The hinge of bivalve shells undergoes many variations in the
different genera. The simplest type is a smooth edentate surface
where the two valves meet and are held together only by the strong
ligament. Generally, however, there is a system of interlocking
teeth, those in the center of the hinge being the /cardinals/ and
those upon either side the /laterals/. In some forms there are rows
of fine comb-like teeth along the hinge-margin, with no distinction
between cardinals and laterals.
The object of these hinge-teeth is at once obvious, for they give a
rigidity and increased strength to the entire mechanism, especially
when closed. There is occasionally a saucer-shaped plate or platform
just under the cardinal teeth and within the shell, called the
/fossette/. Upon this rests the internal elastic cartilage.
Upon the smooth interior surfaces of the valves are always certain
markings, which correspond to anatomical features of the animal and
are consequently of considerable importance in the determination
of the systematic position of the specimen. First, the well-marked
impressions left by the adductor muscles will be noted; then a more
or less distinct line which, describing roughly a circle, connects
the two muscle scars. This line represents the points at which the
mantle became detached from the shell. In other words, all the space
within this /pallial line/ (barring the [pg419] muscle scars) was,
in life, covered by the mantle, which adhered tightly to it. The
space between this pallial line and the outer edge of the valve was
occupied in life by the free portion of the mantle. Frequently a
depression in the pallial line toward the center of the valve is
seen in the posterior end. This is called the /pallial sinus/, and
marks the space occupied by the siphons. The pallial sinus is absent,
moderate, or deep, according as the animal possessed no siphons, or
small or large ones.
The length of bivalve shells is measured from their anterior to their
posterior ends, while the height indicates the greatest diameter
between the umbones and the ventral margin.
The greatest possible degree of variation exists in the structure of
the pelecypod shell. Every degree of thickness from the most fragile,
tissue-like structure to the very heavy and ponderous tests of some
of the /Veneridæ/ is to be found. There is also a range in size
from the very minute /Spheria/ to the giant /Tridacna/ of Eastern
seas, which weighs several hundred pounds. As in the /Gasteropoda/,
there is fortunately a very close parallelism between shell and
anatomical variations. One very quickly learns to place a bivalve in
its systematic position by a mere glance at the shell alone. While
the higher classification into orders, suborders, etc., is based upon
anatomical features, the genera often and the species always are
founded upon conchological or shell characters.
The /Pelecypoda/ offer one of the most interesting fields for
investigation and study among the invertebrates. Although by no means
neglected, they have not received as much attention on the part of
biologists as has been given to other phyla, or indeed to the other
classes of this same phylum.
CLASSIFICATION OF THE PELECYPODA
Nearly every systematic writer upon the mollusks has attempted to
give a good classification of the bivalves, yet none of the results
is wholly satisfactory. The scheme now generally adopted is one based
upon modifications of the gills, or branchiæ, and has practically
replaced all the older classifications, which depended [pg420] upon
the presence or absence of siphons, the degree of mantle fusion,
the arrangement of teeth upon the hinge, the number of adductor
muscles, etc. The idea of arrangement according to gill-structure is
substantially this: the development of the gill from the simplest
and most rudimentary type through successive stages to a higher,
more complex, and presumably more efficient type, marks the natural
progress or development of the pelecypod animal itself. By adopting
the gill as a guide one follows, therefore, a natural method. Upon
the other hand, the presence or absence of siphons, the shape
of the foot, the number of adductor muscles, all depend merely
upon the acquired habits of the animal, these particular features
being subject to modification according to environment and changed
conditions.
The five orders of the /Pelecypoda/ are: /Protobranchiata/,
/Filibranchiata/, /Pseudolamellibranchiata/, /Eulamellibranchiata/,
/Septibranchiata/.
[Illustration: Structure of the branchiæ or gills of pelecypods,
seen diagrammatically in section: A, /Protobranchiata/; B,
/Filibranchiata/; C, /Eulamellibranchiata/; D, /Septibranchiata/;
/e/, /e/, external row of filaments; /i/, /i/, internal row of
filaments; /e´/, external row or plate folded back; /i´/, internal
row folded back; /f/, foot; /m/, mantle; /s/, septum; /v/, visceral
mass.]
The first includes the simpler type of gill as represented in the
accompanying figure (A). Its filaments are short and not reflected.
The second, represented in Fig. B, has the filaments long, reflected,
and connected (each filament to its adjacent ones) by means of
surface cilia. The third type of gill resembles the last except that
the ends of the filaments of the outer gill are attached to the
mantle, and the ends of the filaments of the inner gill are attached
to the foot or visceral mass. The fourth type of gill is far more
highly [pg421] developed. The adjacent filaments are connected, not
by cilia, but by vascular channels, and the depending and recurved
portions of each filament are also connected in a manner presumed to
admit of the passage of blood. This gives to the organ the appearance
of basketwork or network. The ends of the filaments are attached to
the mantle and to the visceral mass, as in the last order, forming
cavities or chambers above (see Fig. C). This order includes the
great majority of the /Pelecypoda/.
The fifth and last order is confined to but two rather obscure
families, in which the gill-development is carried to the point of
substitution of muscular partitions which form a separate chamber
connected with the mantle cavity by a narrow slit, the surface of the
chamber having respiratory functions (Fig. D).
The collector of living marine objects who has become fascinated by
their beauty and who derives pleasure from examining the greater
beauty of their structures will find a rich field for research in
the pelecypod gills. But unless he has time at his disposal and some
skill with a microscope, he would do well not to venture too far into
this alluring but difficult and vexatious subject.
Our coastal waters are fairly rich in bivalves, but the most
strikingly handsome species of this class—and there are many of
them—are inhabitants of warmer seas. Of the great number of bivalves
to be found upon our own shores we can only mention briefly some of
the commonest species.
ORDER =PROTOBRANCHIATA=
FAMILY ~NUCULIDÆ~
In this family the gills are of the simplest and most primitive type.
The mantle-edges are entirely open along the ventral margin, but they
are united posteriorly in some of the /Nuculidæ/ to form two short
siphons. The palps are exceedingly large. The foot is also large,
and by its disk-like surface is adapted to creeping, much as is a
gasteropod foot; its edges are often crenulated or scalloped, and
there is no trace of a byssus. The shells are [pg422] equivalve, and
their most prominent feature is the hinge, which is beset with sharp,
comb-like teeth in two straight rows, one upon each side of a central
pit, a space reserved for the ligament.
GENUS ^Nucula^
^N. proxima.^ The commonest of several species of the genus found
along the New England coast. It is oblique, with a light-olive
epidermis, nacreous interior, and finely crenulated margins. Its
length is about one quarter of an inch. The animal has no siphons.
It lives in either muddy or pebbly stations near the shore, and
probably exists in countless thousands in all the bays and harbors
of the New England coast.
[Illustration: /Nucula proxima./]
GENUS ^Leda^
^L. tenuisulcata.^ This species has a longer shell than the
preceding; it is more produced behind, and is narrowed into a
blunt, slightly gaping point. The epidermis is light greenish, and
the shell has a pearly luster within. The outer surface of the
shell is concentrically grooved; the beaks are smooth. The foot is
disk-shaped, and the animal is provided with small siphons. The
length of this shell is about one inch. Its station is the muddy
bottom in shoal water on the New England coast.
[Illustration: /Leda tenuisulcata./]
GENUS ^Yoldia^
^Y. limatula.^ This species has the same sort of toothed hinge
exhibited in the two preceding species, but the shell is
considerably larger (two inches), with a smooth greenish glazed
epidermis. The beaks are nearly central. The interior of the shell
is light bluish and pearly. The animal has two slender, short,
united siphons and a disk-shaped foot with simple margins. This
species can make excellent use of its foot, for it crawls with
rapidity, and also can execute leaps in an astonishing manner.
Found in muddy stations in shoal water on the New England coast.
[Illustration: /Yoldia limatula./]
^Y. thraciæformis.^ A much larger species, found on the New England
coast. It may be distinguished by a rib-like wave extending
obliquely from the umbones to the ventral margin of the shell. It
measures over [pg423] two and a half inches in length and one and
a half inches in height, and is dark olive-green. The foot is like
that of /Y. limatula/. The labial palps are exceedingly large.
^Y. sapotilla.^ The shell is ovate, prolonged on one side, thin,
fragile, translucent, and covered with a thin, glossy epidermis,
greenish in color. The anterior half is semi-oval, the posterior
portion narrowed and compressed; within it is pearly-white, with a
triangular cartilage cavity, and sixteen to eighteen pointed teeth
on each side. In length it is little less than an inch. Found from
Long Island Sound northward.
[Illustration: /Yoldia thraciæformis./]
[Illustration: /Yoldia sapotilla./]
FAMILY ~SOLENOMYIDÆ~
GENUS ^Solenomya^
Two species of this genus, which are greatly prized by collectors
on account of the extraordinary development of the epidermis of the
shell, occur in New England waters. The strong corneous periostracum
of a deep chestnut-color projects considerably beyond the margins
of the valves; the shells are exceedingly thin and fragile, and are
marked with radiating lines. The two species are easily distinguished
by their difference in size. ^S. velum^ is about one inch long and
one half of an inch high. ^S. borealis^, of arctic range, is quite
twice that size. Their anatomy is similar in essentials to that of
/Yoldia/. These species live near shore in sandy bottoms, and are
occasionally found upon the beach between tides. Chelsea Beach, just
north of Boston, is an often-quoted locality.
[Illustration: /Solenomya velum./]
ORDER =FILIBRANCHIATA=
There are several families of this order which are well represented
in both the Atlantic and the Pacific waters of the United States. The
characteristic feature of this group of bivalves is the filamentous
gill, that is, a gill with the filaments long, doubled back, and
united to each other only by ciliary junctures. These [pg424]
junctures are so slight that they break readily when a specimen of a
gill is handled, leaving the filaments free. The presence of a byssal
gland in the foot, and often a well-developed byssus, is another
characteristic of this order.
FAMILY ~ANOMIIDÆ~
GENUS ^Anomia^
This is a family of peculiar and highly specialized forms. /Anomia/
has an irregularly rounded shell, with one convex and one flat
or concave valve. There is no regular hinge or well-defined
hinge-margin, but a raised fossette, or cartilage plate, occupies a
position at the top of the valves. In the flat valve there is a large
oblong hole just under the apex, through which projects a calcified
byssus, by means of which the animal secures itself to oysters, dead
shells, stones, or any solid object. The anomias, which have become
stationary in habit, have practically lost their foot. The gills are
very large and curved, while all the organs seem to be abnormally
placed on account of the huge byssus and byssal muscle. For the
byssus to pass, as it does, through a specially prepared hole in one
of the valves is an extraordinary departure from the conventional
types of byssiferous species. The heart is not traversed by the
intestine. Altogether, then, /Anomia/ is a very curious genus.
[Illustration: /Anomia simplex/, side view. /Anomia simplex/, from
below.]
^A. simplex.^ The commoner large form of New England. It varies
from one to three inches in diameter, is exceedingly irregular
in shape, and its surface is variously undulated and plaited in
accordance with the surface of the object to which it is attached.
Thousands of these valves, disjointed and separated, are cast upon
the beaches all along our Atlantic coast. They are light green to
salmon- or copper-color, generally fragile and scaly, and have a
peculiarly dulled (as though greased) nacre. [pg425]
^A. aculeata^ is much smaller than the last species, and the
surface of the convex valve is roughened by prickly scales. The
smaller valve is very thin, with an almost circular aperture for
the byssus. Its diameter is about half an inch. Found attached to
stones, etc., about the holdfasts of /Fucus/.
[Illustration: /Anomia aculeata/, from above. /Anomia aculeata/,
from below.]
^A. lampe^, a California species ranging more to the south, is
small (half an inch), and greatly resembles the east-coast /A.
aculeata/, save as regards the smooth surface of the former.
GENUS ^Placunanomia^
^P. macrochisma.^ This species occurs on the Californian coast. It
has the same sort of calcified byssus as /Anomia/, and also the
hole to accommodate it in the smaller valve. The scar formed by the
muscle which controls the byssus is curiously rayed in this genus.
The normal shape of the shell is circular; it is pearly within, and
of a greenish tinge without. Two to four inches in diameter. (Plate
LXXVIII.)
FAMILY ~ARCIDÆ~
GENUS ^Arca^
The /Arcidæ/ may always be distinguished by the long row of comb-like
teeth upon the hinge, the total want of siphons (a fact which may be
discovered in the shell alone by its lack of a pallial sinus), and
the solid trapezoidal or round shell, with its tendency to strong
ribs radiating from the umbones. The periostracum, or epidermis, is
heavy and often velvety or even hairy. The animal of /Arca/ has the
gills placed in an oblique position; the foot is large and strongly
developed. No trace of mantle fusion exists. The mantle-edges bear a
row of composite eyes. The gill-filaments are entirely free, there
being even no ciliary junctions.
[Illustration: /Arca pexata./]
^A. pexata.^ An exceedingly common species in Long Island Sound and
on the coast of New Jersey. The shell is oblong, with prominent
beaks directed forward. The hinge-teeth are arranged in a row
posterior to the beaks, while just under the beaks are a number of
irregular cartilage-pits. About thirty-two to thirty-six radiating
ribs ornament the shell. The inner margins of the shell are rather
deeply scalloped; the epidermis is thick, shaggy, and dark
[pg426] brown. Length two to two and a quarter inches; height two
inches. /A. pexata/ is one of the few pelecypods which have red
blood, a fact which accounts for its popular name of "bloody clam."
^A. ponderosa.^ The most prominent /Arca/ upon our Atlantic
coast, especially south of Virginia. The beaks of this shell are
very prominent, and do not approach each other very closely on
account of the wide dorsal margin of the shells, the large space
between the beaks being occupied by an external ligament. The
hinge-teeth are smaller in the middle. There are from twenty-five
to twenty-eight ribs; the ventral margin of the valves is somewhat
contracted in the middle. Length two and a half inches; height two
inches. Very heavy and solid. This exceedingly common species is
often cast upon the beaches south of Hatteras in numbers beyond
computation. In life it is covered with a heavy, coarse, velvety
epidermis, almost jet-black in color. (Plate LXXVIII.)
^A. noæ.^ The well-known "Noah's-ark" shell, a common species
along the shores of the Southeastern States. It also occurs in
the Mediterranean. Unlike most arcas, it spins a byssus, by means
of which it attaches itself to the under surfaces of stones at
low water. The hinge-margin is perfectly straight and regularly
toothed. The beaks are high and are situated very far forward. The
dorsal margin of the valves is strikingly large, and is marked by
lattice-like grooves; it forms a concave surface over an inch in
width between the umbones. The shell is strongly ribbed without.
The ventral margin of the valves is sinuous and gapes slightly at a
central point for the accommodation of the byssus. (Plate LXXVIII.)
FAMILY ~MYTILIDÆ~
GENERA ^Mytilus^, ^Modiola^
[Illustration: PLATE LXXVIII. Placunanomia macrochisma. Arca
ponderosa. Arca noæ. Mytilus hamatus.]
The /Mytilidæ/ are a large family, including the mussels, so
commonly found between tides upon all shores. The two ordinary
genera /Mytilus/ and /Modiola/, which often occur associated
together upon our eastern coast, may readily be distinguished one
from the other by the position of their beaks. In the former genus
the beak is terminal, that is, it is situated at the very tip-end
of the shell; in the latter genus it is not quite terminal. Aside
from this simple feature, the genera are practically the same, the
animals being identical. /Mytilus/ and /Modiola/, commonly known as
mussels, have acquired the stationary habit and are provided with a
relatively small foot (in some species amounting to no more than a
mere tubercle); but in place of a useful foot is a well-developed
byssogenous gland, which secretes an [pg427] exceedingly tough,
fibrous byssus. By means of this the animal may not only attach
itself firmly to any sort of object, but may actually move about.
Fibers of the byssus are thrown out, and, as though possessed of
life, they seize upon objects in the direction in which /Mytilus/
desires to move, and by contraction of the muscles which control
the byssus the animal is drawn forward, the operation being then
repeated. It must be a very tedious method of travel. However, the
/Mytilidæ/ are not restless creatures. They pass their lives content
to remain firmly fixed to some object, and their movements, if any,
are within a very narrow circle. The animal has very long gills
of the usual filamentous type. The mantle fuses at one point to
form an anal siphon, the lower or branchial one being, therefore,
functional. The palps are large. One curious feature of this group is
the enormous extent of the genital glands, which actually appear to
pervade the entire structure of the animal, gills, mantle, foot, and
all. At times the whole being is a veritable receptacle for myriads
of tiny yellowish eggs.
[Illustration: /Mytilus edulis/, typical form.]
The /Mytilidæ/ are of universal distribution, and are for the most
part of littoral or shallow-water range. Some species are esteemed as
an article of food, notably /Mytilus edulis/.
Mussel-culture has been profitably carried on in France for a long
time, but the genus has not been utilized to any extent as food in
this country. [pg428]
^Mytilus edulis^ is exceedingly abundant along the New England
coast. It lives in colonies, often between tides, in pebbly
stations among large rocks. It is always so fastened by its byssus
that the beaks of the valves point downward, and the ventral margin
projects above the sand or mud. The color of the epidermis in the
adult form is black or a deep blue-black; the shell proper is
violet. Hinge-teeth are wanting. Length two and a half inches. A
variety of this species, ^M. pellucidus^, is often found associated
with the typical form. It is brightly rayed in green and yellow.
/M. edulis/ occurs in Europe, where it is quite extensively used as
food. It also occurs (by importation) in San Francisco Bay.
[Illustration: /Mytilus edulis/, rayed-color variety.]
^M. hamatus^ has a more southern range than has /M. edulis/, and
is found from the Chesapeake southward. Its shell is considerably
twisted just below the umbonal region, while its whole surface is
densely striated. Its color is dark fuscous. Length one to two
inches. It is found in great numbers attached to oysters by its
byssus. In Florida it is very common. (Plate LXXVIII.)
^M. californicus.^ A common west-coast species, which finds its
station among rocks exposed to the surf. It is about the same size
as /M. edulis/, but has a lighter brownish glossy epidermis and
several conspicuous, well-rounded, radiating ribs. The animal is
orange-colored.
[Illustration: /Modiola modiolus./]
^Modiola modiolus.^ After violent storms upon the New England
coast, when a large /Laminaria/ is wrenched from its rocky bed
and washed ashore, its roots will, in many cases, be found
clinging to this large mussel. The thick glossy epidermis of deep
chestnut-color folds over the margin of the valves, and the outer
surface, especially near the ventral margin, is covered with a
tough hairy growth. Length four to five inches. The animal is
orange-red. The great size and swelling fullness of this species
at once distinguish it from all others upon our coast. It is not a
shallow-water form, but is extremely common upon all beaches north
of Hatteras. It also occurs in Alaskan waters to Puget Sound, where
it is known as the "great horse-mussel." Sometimes these large
modiolas may be found in rocky tide-pools which are washed by the
surf at high tide. They hide far back in the crevices of boulders,
and [pg429] are not easily detected. They are not uncommon in
such stations at Mount Desert, Maine.
[Illustration: /Modiola plicatula/, typical form.]
^M. plicatula.^ This species of /Modiola/ ranges from Canada to
Hatteras, and inhabits the tidal waters of streams, sheltered
muddy reaches among reeds, and tidal flats. It is a dingy-looking
shell, ornamented with numerous radiating ribs, which are very
fine upon the anterior portion of the shell. The epidermis is thin
and of a dirty yellowish-green color. Within it is silvery-white.
In the ventral margin there is an opening for the accommodation
of a byssus. Length about three inches in New England; slightly
larger at Norfolk. There is probably no muddy reach of land that
is exposed at low tide from Maine to the Carolinas that is not
inhabited by /M. plicatula/.
^M. tulipa.^ This is the "show shell" of the genus /Modiola/ in
American waters. It belongs to the Southern fauna, and, like the
others of its genus, it moors itself to wood or other solid objects
by means of its byssus. It is of about the same size as the last
species, but is perfectly smooth and of a bright-yellowish color,
with dark rays over the central portion.
[Illustration: /Modiola nigra./]
^M. recta.^ A species of /Modiola/ fairly abundant on the Pacific
coast from Vancouver to southern California. It has a long, narrow
shell with a dark-brown glossy epidermis; lighter posteriorly, and
with a short hairy growth. The interior is white. Length three to
four inches.
ORDER =PSEUDOLAMELLIBRANCHIATA=
This third order of /Pelecypoda/ is made up of a number of families
in which the gills are filamentous, but in which the filaments
[pg430] have become united at their ends to the mantle (on the outer
gills) and to the body-mass (on the inner gills). Here also the first
traces of the higher type of gill found in the next order appear;
that is, a gill in which the filaments are connected by vascular
channels instead of by cilia. This order therefore is presumed to
connect the true filamentous type of gill with the fully developed
lamellar type. As the filaments do not always fuse with the mantle
or foot, the description of the pseudolamellibranch gill becomes
somewhat vague, and there is some room for doubt whether this order
should exist at all.
Most of the genera placed in it are monomyarian; that is, they have
but one adductor muscle, or if two, the anterior one is very small
and unimportant. The mantle-edges are entirely open, there being no
regularly formed siphons. As a rule, the foot is exceedingly small or
quite aborted.
FAMILY ~AVICULIDÆ~
In this family there is an exception to the rule just stated: the
foot is long. There is a byssus, and the gills (by their outer
ascending filaments) are concrescent with the mantle.
The interior of all the /Aviculidæ/ is of a highly polished nacre,
and some of the larger species have been extensively collected
for mother-of-pearl. To the /Aviculidæ/ belong the pearl-oysters
(/Meleagrina margaritifera/).
A delightful air of romance and adventure surrounds the
pearl-fisheries, about which much has been written. The pearl
is an abnormal product formed by the deposition of nacre around
some foreign object, such as a grain of sand, or—usually, it is
said—an egg which has failed to develop properly. They are seldom
found in individuals having favorable conditions of growth, but
those which are greatly crowded together and covered with various
parasites and growths are most productive of them. The pearl is
the same in substance as the nacreous shell of the pearl-oyster,
and its iridescence is due to the fine striæ of the undulating
layers of which it is composed. The pearl as well as the shell
is produced by the shell-glands of the mantle. The value of the
[pg431] pearl is based on the brilliancy of the nacre, the size,
and the form. Luster, or "orient," is to the pearl what brilliancy
is to the diamond. The round form has the greatest value, next
the pear-shape, and lastly the oval. Pearls of inferior value are
produced by other species than /Meleagrina margaritifera/, the true
pearl-oyster. Many bivalves secrete similar bodies, but as they have
the nature of the shell, those produced by mollusks having lusterless
interiors are of no value. Beautiful pink pearls are found in the
gasteropod /Strombus gigas/, the conch-shell of the West Indies. The
shells of the pearl-oyster are themselves very valuable, being the
"mother-of-pearl" used in the manufacture of buttons, knife-handles,
inlay-work, and so on. They have three grades of commercial value; of
the first are the "silver-lipped," from the South Seas, of the second
the "black-lipped," from Manila and Ceylon, and of the third the
"bullock-shells," from Panama.
GENUS ^Avicula^
^A. atlantica.^ A Floridian species which is often found attached
by its byssus to large algæ which have been washed upon the beach.
The shell is reddish-brown, with many white radial lines. Its
obliquely oval shape, the long wing-like extension of the dorsal
margin, the inequivalve shells, and the byssal sinus placed just
below the forward extension of the hinge, are characteristics which
will enable one to recognize the species at once. The structure of
the shell is unusual in being so largely composed of organic matter
that it possesses elasticity near its thinner edges.
GENUS ^Pinna^
^P. muricata^ and ^P. seminuda^. Two species of this family which
are very abundant in Floridian waters and are often to be found
associated upon the muddy or sandy shores of bays. Like /Modiola
plicatula/, they attach themselves by means of their byssus to
shells or stones which lie under the surface. With the pointed end
of the shell directed downward, they remain almost wholly concealed
in the sand. Only about one quarter of an inch of the broad end
of the shell projects above the sand. The edges of the valves are
as sharp as knife-blades, and great caution must be used while
walking barefooted along a beach inhabited by /Pinna/. The shells
of both species are of a triangular wedge-shape and are composed
of a translucent crystalline matter. /P. muricata/ is beset with
triangular erect scales which project out like spines. Their edges
are also sharp like pieces of broken glass. /P. seminuda/ also has
these raised scales, but they are far more numerous [pg432] and
much smaller, and are arranged in closely packed radiating rows,
the scales becoming obsolete near the umbones. The mantle of the
animal is doubly fringed, and much decorated upon that portion
which may be protruded from the shell. The posterior adductor is
very large and strong; the anterior one has almost disappeared. The
foot is long and slender, but is evidently a useless appendage,
for the animal's habit is stationary. The byssus is large and very
strong. Gloves have been made from the byssal fibers of /Pinna/
mixed with silk. The gills are very long and are distinctly /not/
filamentous, the adjacent filaments being clearly united by
vascular channels. A very curious development of the osphradium
(see page 339) into an erectile process capable of projection
beyond the margin of the shell is a unique feature of /Pinna/.
Sometimes thousands of pinnas are torn loose by storms and cast
upon the beaches. They do not range north of Hatteras. (Plate
LXXIX.)
GENUS ^Perna^
^P. ephippium.^ A West Indian shell, also quite common on the
east coast of Florida, and especially upon the Keys. It attaches
itself by the byssus in great bunches to mangrove roots, sticks,
and all manner of rubbish in brackish water. It has a very flat,
irregularly shaped shell of a horn-color, and is from two to
three inches across. The distinguishing feature of /Perna/ is the
hinge. It is straight and without teeth, but is marked by a row of
transverse grooves to which the ligament is attached. These grooves
constitute a row of cartilage-pits.
FAMILY ~OSTREIDÆ~
This family probably interests more people than any other one in the
class save /Aviculidæ/. The latter furnishes the pearl-oysters, the
former the edible oysters, the two thus appealing to two very strong
human cravings—those of vanity and hunger.
[Illustration: PLATE LXXIX. Pinna muricata. Pinna seminuda. Pecten
hastatus.]
Few realize what an enormous business the oyster trade has become
in the United States. The value of it is stated to be over thirteen
million dollars annually, twenty-five million bushels of oysters
being taken from the Chesapeake alone. The edibility of the
oyster has been known from early times, for vast heaps of empty
oyster-shells, known as kitchen-middens, occur in various parts of
the world. Some of them are of such size and extent as to warrant
the belief that their formation must have required centuries.
Shell-mounds are found along the coasts of Florida and are of some
archæological value. The cultivation of oysters as recorded by Pliny
dates from the first century B.C., at which [pg433] time a Roman
named Sergius Orata first cultivated oysters at Baiæ. The acuteness
of the gastronomic sense of a Roman epicure is thus described by
Juvenal:
He could tell
At the first mouthful if his oysters fed
On the Rutupian or the Lucrine bed
Or at Circeii.
The poet Gay's opinion is expressed thus:
The man had sure a palate cover'd o'er
With brass or steel, that on the rocky shore
First broke the oozy oyster's pearly coat,
And risk'd the living morsel down his throat.
The methods employed in oyster-farming resemble those of agriculture,
in that the bed is prepared, seed is sown, superfluous and foreign
growths are weeded out, enemies are driven off, and the crop is
harvested at stated seasons. The oyster is ovoviviparous; that is,
it retains its eggs until they are partly matured. These are held in
the gills and mantle folds until the time of spawning, which begins
in May and lasts through the summer months. The larvæ are ejected as
ciliated spheres, called spat, and swim freely about for some time,
often several days, before finding a resting-spot. The oyster-grower
secures many of the larvæ by placing in their way substances to
which they can attach themselves. The American culturist strews his
carefully prepared beds with empty oyster-shells, on which the spat
settle, and the seed is thus secured; for the spat, once fastened,
lose the power of locomotion and become fixed. At the end of a year
the shells which hold the young oysters (now about an inch long
and called "fry") are taken up, and the fry are thinned out and
replanted, or are sold to other oyster-farmers.
During the period of their growth the oysters are sometimes
transplanted several times. At the end of three to five years they
have attained marketable size, and the beds are then harvested and
prepared for another crop. Some oystermen have several acres of
bottom under cultivation. These areas are obtained by purchase or
grant from the State, and their limits are as defined [pg434] as
are the fenced-off acres of upland meadows. The business of the
oyster-culturist is to plant the young oysters and watch their
development, keeping the beds thinned, that the oysters may not be
too crowded for their normal and symmetrical growth, and protecting
them from their enemies, of which there are many. The principal
enemies of the oyster are the starfish and the predaceous mollusks
/Urosalpinx/ and /Nassa/. Whole beds have been known to be destroyed
in a single night by the visitations of starfishes, hence a constant
watchfulness is required on the part of the oysterman. Policing the
oyster-farms is another of his cares, for pirates abound, and a bed
may be robbed in the night as easily as an orchard may be despoiled
of its fruit. Oyster-culture is carried on extensively in Long
Island Sound, on the coasts of New Jersey and Virginia, and in the
Chesapeake Bay. The oysters from certain localities are esteemed more
than others, the flavor of the oyster being very dependent upon the
purity of the water and on the organisms upon which it feeds. It has
been definitely shown that oysters grown in contaminated waters have
been the agents of transmitting disease, notably typhoid fever and
cholera.
Oyster-culture has reached the highest degree of perfection in
France, where miles of muddy shores left by the ebb-tide are utilized
for the purpose. The famous /parc/ at Arcachon, covering ten thousand
acres, illustrates the system generally practised. The spat is there
collected on tiles coated with cement, piled in layers crosswise, and
secured in crates. These tiles are exposed in favorable localities
and collect the swimming embryos. The rough cement holding the
spat is then chipped off the tiles and placed in wire trays. These
/ambulances/, or /caisses ostreophiles/, placed between short posts,
protect the fry from their enemies. At low tide the young oysters
are carefully examined and sorted, and at the right age they are
removed to open areas. The parc is divided into regular squares by
canals of suitable width, some of the squares having banks and gates
to retain the water of the receding tide if desired. Each man's parc
is separated from that of his neighbor by canals of greater width,
and often by stakes having a few branches on the ends. These [pg435]
/pignons/, which sway in the wind, are said to frighten away the
predaceous ray which is apt to hover about the preserves. The parcs
are finally thinned out by sending the oysters to other parcs to be
fattened. There is a celebrated /parc d'élevage/ at Marennes. It is
a collection of artificial ponds, the floors of which are covered
with algæ, which harbor vast numbers of diatoms and other microscopic
organisms on which the oysters feed. The green diatom (/Navicula
ostrearia/) gives to the oysters of Marennes the green color and
peculiar flavor which is so much esteemed by the epicures of France.
To the American, however, the green oyster is not acceptable.
GENUS ^Ostrea^
^O. virginica.^ A description of this species, our common oyster,
is hardly necessary. Every one has seen the rough, shaggy, unlovely
shell. The hinge is toothless, but has a wide depression for the
ligament. The animal, having stationary habits, has practically no
foot at all. There is but one large adductor muscle, around which
curve the gills, the latter being united to each other posteriorly.
The mantle margin is finely and doubly fringed. Although /Ostrea/
is a stationary mollusk, it has no byssus.
/O. virginica/ has been introduced at San Francisco, where it
lives well, but does not seem to multiply very rapidly. The native
species, ^O. lurida^, is about two inches long, dark in color, and
stained a purplish hue. It is not very delicately flavored.
^O. frons.^ This species has a thinner shell than /O. virginica/,
with coarsely serrated margins. It occurs in beds in the
neighborhood of mangroves all along our South Atlantic shores. It
cannot compare with its Northern relative in flavor, but, like the
European ^Ostrea edulis^, it is sometimes "not bad."
FAMILY ~PECTINIDÆ~
GENUS ^Pecten^
The scallop-shells (/Pecten/) are objects too familiar to require
any general description. The rounded valve, usually ornamented with
radiating ribs, and the wing-like projections (called "ears"), from
each side of the umbonal region, are never-failing characters. The
outline of /Pecten/ has been considerably employed in conventional
designs for mural decorations; indeed, the figure [pg436] of a
well-known Mediterranean pecten (/P. jacobius/), found commonly
in Palestine, became an emblem of religious significance during
the middle ages. Returning crusaders fastened to their garments a
specimen of "St. James's shell" as an evidence of the fact that they
had been to the Holy Land, and the design of the shell came to be
adopted upon many coats of arms and also in the insignia of various
orders of devout and adventurous knights of the middle ages.
The animal is of the highest type of monomyarian mollusks, that is,
of bivalve mollusks with only a single adductor muscle. Unlike most
pelecypods, which have a very small foot, /Pecten/ rarely has a
byssus, and is neither a stationary nor a sluggish creature. It can
propel itself through the water by spasmodically closing and opening
its valves, in an eccentric, darting sort of flight, though most of
the time it rests quietly upon the bottom. The mantle is entirely
open and highly ornate about its margin, which is, furthermore, the
seat of many eyes, capable, apparently, of no mean degree of vision.
The adductor muscle is very large and strong, and occupies a central
position, about which the gills circle; the latter are plainly
filamentous.
^P. magellanicus.^ The largest of the east-coast species of
/Pecten/. It is a Northern species, and was long known by the
name of ^P. tenuiscostatus^—a name given to it on account of
its very numerous radiating striæ; but it was later discovered
that the North Atlantic form was in reality the same as the /P.
magellanicus/ of Patagonia. The latter being the older name and
entitled to priority, our shell became /P. magellanicus/, the
other name falling within its synonymy. The length and height of
this scallop are from five to five and a half inches. One valve
is more convex and slightly larger than the other, the smaller
being lighter in color. The valves gape considerably along their
upper margin below the hinge. The cartilage-pit is deep. North of
Cape Ann this large species is of common occurrence in moderately
deep water. The deeper bays and arms of the sea which everywhere
penetrate the Maine coast are its favorite resorts. A good way
to catch pectens is to lower a fishing-line at a spot where the
fishermen report "scallop-ground," and drag it along over the
bottom. Sooner or later it will enter the open shell of some
pecten, which will instantly close its valves upon the string and
allow itself to be drawn out of the water. In Maine these large
scallops are eaten, but they have not found great favor in the city
markets. In color they vary from reddish through brown to ashen.
^P. islandicus.^ A species not so large as the last, with more
prominently raised ribs (about fifty to one hundred in number),
which are [pg437] covered with a multitude of erect scales. The
ribs persist upon the interior of the shell. The "ears" are unequal
in size. The color is light orange to reddish-brown, with zones of
darker and richer color. One valve is flatter than the other and
more lightly colored. Greatest length about three inches; height
three and a half inches. This is a Northern shell, belonging to the
waters of Newfoundland, but its valves are frequently cast upon the
New England beaches.
[Illustration: /Pecten islandicus./]
^P. irradians.^ The common shallow-water species of the Atlantic
coast. This exceedingly abundant species does not range north of
Boston, but finds an extensive habitat to the south. Its metropolis
is Cape Cod, Long Island Sound, and the Jersey coast waters. This
is the true scallop of the Boston and New York markets. Only the
adductor muscle is eaten. In this species there is not so marked
a difference in the convexity of the two valves. There are about
twenty elevated and rounded ribs, the spaces between them being
also rounded. The color is variable, from a blackish horn to ashen
gray. The "ears" are equal; the interior is shining, and grooved
to correspond with the external ribs. Length two and three fifths
inches, height two and a half inches. On clear, calm days the
immature individuals of this species may often be seen in shallow
water disporting themselves most gaily, skipping about and snapping
their valves in great glee. Their mantle margins are very ornate
in scarlet or orange, with rows of bright-blue eyes. Care must be
taken in handling scallops, especially the large /P. magellanicus/,
for a finger caught between the valves will be badly bruised.
^P. dislocatus.^ South of Hatteras this species takes the place of
its Northern relative, /P. irradians/. It is somewhat more globular
and perhaps not quite so large, but the resemblance between the two
species is very marked. It has from twenty to twenty-two rounded
ribs, with very numerous concentric wrinkles between them. In
color it is white, tinged with purple or yellow, with occasionally
a system of blood-red lines crossing the ribs transversely. The
diameter is about one and a half inches. This species has the
same playful habits as /P. irradians/, and is not at all easy to
capture. When pursued it dives into the mud, and sets up such a
commotion by the spasmodic opening and shutting of its valves that
the water at once becomes roiled, and the scallop is safely hidden
in its murky depths. [pg438]
^P. hastatus.^ There are several very beautiful pectens on the
Pacific coast of the United States, and two of these—one of
northern and the other of southern range—resemble very closely
the two Atlantic species of relatively north and south range, /P.
islandicus/ and /P. irradians/ or /dislocatus/. The first is /P.
hastatus/ of Puget Sound. Valves of this exquisite shell are even
occasionally found in California. It has very much the aspect of
/P. islandicus/—unequal ears and an ovate form. The most curious
thing about this shell is the fact that a different system of
sculpturing exists upon the two valves. Upon one the ribs are even
and the whole surface is covered with raised scales; upon the other
the ribs are alternately of large and small size. Color rose-pink,
with deeper bands; one valve lighter-colored, suffused with
delicate pink. Height two and a half inches. (Plate LXXIX.)
[Illustration: /Pecten irradians/, typical form.]
^P. æquisulcatus.^ The Southern species above referred to as
resembling /P. irradians/ or /dislocatus/. It has about twenty
stout, well-rounded ribs, with concentric wrinkles between
them. The "ears" are equal. The size and shape are as in /P.
irradians/. The coloring is whitish, varying to shades of brown,
and excentrically marked with spots or waving transverse lines of
chestnut or horn.
ORDER =EULAMELLIBRANCHIATA=
With the pectens we leave behind all pelecypods with the true
filamentous type of gill. In the order /Eulamellibranchiata/ we find
all the families to be possessed of the basketwork or crisscross
branchial structure. Each gill is fundamentally formed of filaments
which project downward, and then suddenly turn upon themselves and
ascend; the ascending and descending limbs are connected, however, by
processes of presumably vascular function, and adjacent filaments are
connected by truly vascular channels. The closer connection of the
filaments to form of each gill a sort of plate is further effected
[pg439] by connective tissue, which sometimes is dense enough (though
always porous) to obscure the reticulated appearance of the organ.
Furthermore, the edge of the outer lamella of the outer gill unites
with the mantle; likewise the edge of the inner lamella of the inner
gill unites with the body-mass, and /behind the body-mass/ with the
gills upon the other side of the animal. This union of the four gills
in a straight median line behind the foot and body-mass forms a
septum, which divides off from the mantle cavity a "suprabranchial"
cavity. Into this cavity the excreta are discharged, and with it the
anal or excurrent siphon connects. The branchial or incurrent siphon
thus pours its current of water into the /lower/ mantle cavity, to
bathe the gills and feed the mouth, while the fresh water is not
contaminated by any open and wide connection with the excretory
processes. In many of the forms where the siphons are very long and
united, this septum, formed by the union of the dorsal edges of the
inner gills back of the foot, is continued far into the siphons,
constituting the division of the two into the anal and branchial
siphons.
Another feature of this order is the marked tendency to mantle
fusion. As there are always siphons, the mantle-edges must
necessarily have fused at two points at least, in order to have
formed the siphons. The tendency, however, is for the fusion to
continue, narrowing the pedal opening more and more, as though the
mantle were endeavoring to envelop the entire animal in a bag or sac
open only at one end (siphonal opening), but yet slightly ripped
along one seam (pedal opening).
This order includes the great majority of pelecypods, and admits of
many very confusing modifications in its most essential features.
FAMILY ~CARDITIDÆ~
In this, the first family of the order, most of the characteristic
features just spoken of are present. Mantle fusion, however, has
not progressed beyond a degree which is just sufficient to form the
siphons. There is a byssiferous gland. The name /Carditidæ/ refers to
the heart-shape of the shells. [pg440]
GENUS ^Cardita^
[Illustration: /Cardita borealis/, natural size.]
^C. borealis.^ A very common species north of Cape Ann, reported
also in deeper water as far south as Hatteras. It is a solid,
obliquely heart-shaped shell, with beaks elevated and turned
forward. It has about eighteen to twenty rounded radiating ribs,
which are broader than the grooves between them. The epidermis
is rusty-brown. The hinge is strong, with two prominent teeth;
the margins of the shell are strongly crenulated within.
Length one inch; height about the same. This is not strictly a
between-the-tides species, but its valves are often cast upon the
beaches. Fine specimens may be obtained by dredging at Bar Harbor
or Eastport.
^C. floridana.^ A very common Floridian species. Its seventeen or
eighteen ribs are very heavy, and are rendered nodulous by the
numerous bluntly raised scales upon them. The shell is lengthened,
and has a well-defined lunule and an external ligament. In color
it is yellowish-white, with purple markings when young. Length one
inch; height three fourths of an inch. It lives in sheltered bays;
detached valves are often found cast upon the beach.
FAMILY ~ASTARTIDÆ~
GENUS ^Astarte^
Notwithstanding their rather small size, there is a trimness about
the shells of /Astarte/ which, taken together with their rich
chestnut epidermis, makes them very interesting and desirable
additions to the cabinet. The family is one of cold-water range, with
a few representatives on the New England coast. Live specimens are
not easily captured, for they live in deeper water than one would
care to wade in, nevertheless they are frequently cast upon the
beaches after storms. The animal has a very short efferent siphon,
large labial palps, and very obliquely placed gills. Not more than
twenty living species of /Astarte/ are known, and all of them belong
in, or are wanderers from, polar seas. Fully three hundred fossil
species of this genus have been described from Mesozoic rocks in all
parts of the world. The question naturally arises whether in these
its dying days /Astarte/ has sought colder waters in which to pass
its remaining existence, or whether climates have changed. The fact
that such strictly [pg441] tropical genera as /Voluta/ and /Conus/
are found fossil in northern Siberia seems to be evidence in proof of
great climatic variations.
^A. castanea.^ This species has a thick and heavy shell for one
so small, with round ventral margins and prominent beaks. The
surface is very slightly undulated and is covered with a thick
chestnut epidermis with pale and dark zones. The hinge is broad and
flat, with a prominent cardinal tooth upon the right valve, which
accurately fits into a pit formed by two teeth on the left valve.
Length one inch; height one inch.
[Illustration: /Astarte castanea./]
^A. undata.^ A species slightly larger than the last, with ten to
twenty prominent concentric undulations.
[Illustration: /Astarte undata./]
The identification of the many species of /Astarte/ often becomes
exceedingly difficult on account of the fact that the genus is a
remarkably uniform one in its main characters and is infinitely
variable in its minor details.
FAMILY ~CYPRINIDÆ~
GENUS ^Arctica^
This family is represented by one species upon the New England coast,
which is much sought after by collectors. It is one of the larger
clams, but is too uncommon to have received a popular name and to be
generally well known by the fishermen along the shore.
[Illustration: /Arctica/ (/Cyprina/) /islandica/.]
^A.^ (^Cyprina^) ^islandica^. This clam has a thick though not
ponderous shell, with prominent beaks and a stout, prominent
ligament. Its cardinal teeth are large, but its laterals are very
small. A striking feature of this species, which at once separates
[pg442] it from all other shells of our coast of similar size,
is the coarse, wrinkled epidermis of black to chestnut color.
The shell is very suggestive of a large, overgrown /Astarte/.
Length three and a half inches; height three inches. It is found
of all sizes, down to one fourth of an inch in diameter, upon
muddy stations in moderately deep water near the mouths of rivers;
but the surest way to get it is to search the beach after a hard
onshore gale.
FAMILY ~LUCINIDÆ~
This family finds its metropolis in warmer waters, and the best
representatives of it must be sought for upon the Floridian beaches
or in the shallow bays of that sandy coast. A long vermiform foot
is a characteristic of the animal, as is also the fact that at
times there is only a single gill upon each side of the body. In
some of the /Lucinidæ/, more so than in most other pelecypods, the
chief function of the gills is to furnish a brooding-place for the
thousands of ova which the creatures generate. Sometimes a /Lucina/
will be captured with the gills swollen out of all proportion,
and literally stuffed with tiny, microscopic eggs. At such times
the gills lose all semblance of branchial organs. The shells are
orbicular, with depressed small umbones, a distinct lunule, a
semi-external ligament, two cardinal teeth, and laterals (a variable
feature). There is no pallial sinus. The color is white, and the
outlines are rounded.
GENUS ^Lucina^
^L. tigrina.^ The largest of the group, measuring three inches
across and nearly the same in height. It is flatly convex and
radially ribbed by a great number of costæ which are crossed and
decussated throughout with concentric ridges. The color is white.
This fine shell lives only in southern Florida and is abundant in
shallow water on sandy stations. (Plate LXXX.)
^L. floridana.^ One of the most abundant bivalves in Florida, often
cast in thousands upon the beaches. It lives in shallow protected
waters and upon sand-flats which are partly exposed at low tide.
It has the usual round outlines of the genus, with exceedingly
small umbones, directed forward, and a smooth surface, save for
fine growth-lines of a light straw-color. The shell is pure white.
Diameter about one inch. (Plate LXXX.)
^L. pennsylvanica.^ A species often associated with the last,
but about twice as large. Its thin but tough epidermis clings
to the shell in raised concentric lines, giving it a circularly
ribbed appearance. The most prominent feature of this species is
a depressed line upon either valve extending obliquely from the
umbones to the posterior ventral margin, [pg443] causing, at the
margin, a pucker or break in its even continuity. The lunule is
large and ribbed; the teeth are small; the color is pure white,
with a light straw-tinted epidermis. (Plate LXXX.)
^L. dentata.^ In this species the shells are thin and white, with
well-marked concentric lines crossed by deep oblique narrow furrows
bent at nearly right angles to the lines of growth and forming
teeth around the margin. Found along the entire coast.
[Illustration: /Lucina dentata./]
^L. californica.^ The best-known California species of this genus.
It is pure white, with fine concentric lines, and varies in size
from one half of an inch to one and a half inches in diameter. The
lateral teeth are the stronger, and the lunule is upon the right
valve only. With these exceptions this species preserves the usual
characters of this genus.
^L. nuttallii^, belonging to the southern shores of California, is
decussated like fine wickerwork. The shell is flattened and ridged
along the hinge-margin. The color is white. Diameter about one inch
in large specimens. (Plate LXXX.)
GENUS ^Loripes^
^L. edentula.^ A species which is seldom captured alive. Its
home is in the open sea, but vast quantities of its valves are
occasionally thrown upon the beaches south of Hatteras, as far as
the Gulf of Mexico. On account of the weak hinge ligament, the
valves become easily separated, and it is not always easy to find
two that will exactly match. /Loripes/ preserves the same circular
outlines as /Lucina/, but is more ventricose, and the hinge and
teeth are very feeble. This species is a little over two inches in
length and slightly under two inches in height. It is pure white
without, and is finely striated with growth-lines; bright orange
within, especially about the pallial line and muscle-scars. (Plate
LXXX.)
FAMILY ~TELLINIDÆ~
GENUS ^Tellina^
If we should create an aristocracy of beauty among the bivalves, as
has been done by conchologists among the gasteropods, this family
would deserve high rank. Most of the American species of /Tellina/
are too small to impress one very greatly with their beauty, but
in the West Indies and in the tropical Pacific waters are some
wonderfully handsome shells belonging to this or to the allied genus
/Macoma/. However, we have in Florida the very striking /T. radiata/,
a truly beautiful shell, which, were it less common, would be highly
prized in collections. Rarity, no doubt, adds a wonderful luster
to shells as well as to gems. The [pg444] animal of /Tellina/ has
long, slender siphons, which are separate. The gills are small, and
the outer lamella or branchial fold is directed dorsally. Although
the foot shows evidences of a byssogenous gland, there is no actual
byssus. The shells are porcelanous and translucent, equivalve, with
an external ligament, and at least two cardinal teeth in each valve.
^T. radiata.^ This species varies from three to four inches in
length, and from one and a half to one and three fourths inches
in height. It is highly polished, shining white, and yellowish
about the umbonal region, and has three wide rays of bright pink
extending from the beaks to the ventral margin. On account of its
remarkable coloration it is called the "setting-sun shell." Its
surface is smooth. A common variety is of a uniform creamy-white
color with carnation beaks. This shell is always offered for sale
by the marine curio- and shell-dealers in Florida seaside resorts,
and at Atlantic City, Cape May, and elsewhere.
^T. alternata^ resembles the last in shape, being flattish and
oblong, but it is more pointed or angulated posteriorly. There is
also a slight twist in the posterior end of the shell. Its surface
is decorated by numerous impressed concentric lines. The color is
uniformly white or yellowish, with pink rays. Length two and a half
to three inches; height two and a half inches. Found from Hatteras
to the Gulf of Mexico, in shallow, sandy stations and on beaches
after storms. (Plate LXXXI.)
^T. bodegensis.^ The most striking species of /Tellina/ found on
the west coast, and of rather northern range. It is about two
inches in length, creamy-white in color, and ornamented with very
fine concentric lines. A very characteristic feature of the genus
is present in this species as in the last, namely, a slight twist
or bend to one side in the posterior end of the shell.
[Illustration: /Tellina tenera/, showing extended animal.]
[Illustration: /Tellina tenera./]
^T. tenera.^ A little /Tellina/ found in New England waters, which,
though very small, is worthy of mention on account of its abundance
upon all our beaches north of Hatteras. It is only about half an
inch long, and slightly over one quarter of an inch high. It may
be distinguished by its general generic characters, its iridescent
surface, and its delicately marked lines of growth; sometimes
it is rose-tinted. Its remarkably long siphons are shown in the
accompanying figure.
GENUS ^Macoma^
^M. secta.^ A very pretty thin glossy shell from two to three
inches in length and about one fourth less in height, which
occurs from Monterey southward. The posterior end of the shell is
contracted and slightly bent; the pallial sinus is deep. There is
an external ligament. (Plate LXXXI.)
[Illustration: PLATE LXXX. 1, Lucina tigrina. 3, Lucina
pennsylvanica. 2, Lucina floridana. 4, Lucina nuttallii. 5, Loripes
edentula.]
[Illustration: PLATE LXXXI. 1, Tellina alternata. 3, Donax
variabilis. 2, Macoma secta. 4, Donax californicus. 5, Ræta
canaliculata.]
^M. nasuta.^ Another Californian species, with a less shining
surface and a very thin light-brownish epidermis. The twisting of
the posterior [pg445] margin is striking. It has very fine
cardinal teeth. Length two to three inches.
^M. baltica^, ^M. proximo^, ^M. tenta^. The first two of these
species are dingy in color, and are covered with a dirty-looking,
thin epidermis. The first has a wide range to Norway and Scotland,
and is exceedingly common all along our coast from Maine to
Georgia. It occurs plentifully in the Hudson River above New York,
and in all sandy or muddy bays. It is rounded in outline, while the
next species (/M. proxima/) is more pointed posteriorly. When these
species are buried in the sand their two long, slender siphons
project above, one supplying the animal with a constant current
of fresh water, and the other ejecting that which, having passed
the gills and labial palps, is exhausted of its air and nutriment
and contaminated by waste products. /M. tenta/ is white, with very
fine lines of growth, and polished and shining within. It is warped
posteriorly. Length three fifths of an inch; height two fifths of
an inch.
[Illustration: /Macoma baltica./]
[Illustration: /Macoma tenta./]
FAMILY ~DONACIDÆ~
GENUS ^Donax^
The /Donacidæ/ are represented upon our coasts by comparatively
few species, all belonging to the genus /Donax/. The shells are
under an inch in length, and have a peculiarly shortened anterior
portion; thus they are inequilateral. Their ventral margins are
finely denticulate. The pallial sinus is deep. There are two or three
cardinal teeth and a variable number of laterals.
^D. variabilis.^ This little shell, the common Floridian form,
exhibits every imaginable scheme of color-combination, and defies
general or comprehensive description. Probably the most usual
pattern developed is a bluish-white background with purplish
radiating lines. Another is a pure-white foundation with red
lines. The surface is striated longitudinally with excessively
fine riblets. Length one half of an inch or slightly more. In
March and April these shells are thrown alive in millions upon the
Florida beaches. Each wave seems to be laden with them, and when
the foaming waters of each spent breaker recede, the little shells
lie still upon the sand for a moment, glittering like jewels in the
sunlight; then, with a sudden protrusion of the foot and a quick
turn, they all disappear like a flash, buried in the sand before
the next breaker strikes them. One must be very quick to catch
these active little mollusks. (Plate LXXXI.)
^D. californicus.^ Professor Keep very aptly describes this shell,
which is very common in California, as "short and stumpy, cut
nearly square off at one end (anterior), and tapering to a rounded
edge at the other." The same description fits both this and the
Floridian /D. variabilis/ so well that the two forms may be one
and the same species. [pg446] If they were shells of arctic
range it would be easier to connect them; but as neither is a
cold-water form, it becomes more difficult to place them under one
name. The increasing number of similar species being found upon
the Atlantic and Pacific sides of Central America points almost
conclusively to the existence of a waterway between the two oceans,
somewhere between North and South America, at no very remote
geological period. Possibly the closing of some such waterway
through the isthmus connecting the oceans has separated these forms
geographically, thus leading us to separate them specifically.
(Plate LXXXI.)
FAMILY ~MACTRIDÆ~
This is a very large family of universal distribution and with a
great number of genera and subgenera, rather confusedly gathered
into subfamilies. The dominant genus /Mactra/ comprises the largest
bivalve upon the east coast of the United States.
GENUS ^Mactra^
The mactras live in the sand near the margin of the water, often
upon the exposed open coast. The mantle is open, except where it is
fused to form the siphons. These are short and united. The outer gill
is dorsally directed; that is to say, it does not depend into the
mantle cavity as does the inner gill, but projects just the other
way; it is also smaller than the inner one. The foot is strong,
bent, and tongue-shaped, and no doubt well adapted to the rough life
in the surf and the heavy, shifting sands. The main characteristic
of the mactra shell is the prominent triangular-shaped fossette,
or cartilage plate, situated internally and just under the beaks.
The shells are equivalve, and devoid of bright colors or striking
sculptural features. Internally the pallial line is plain, and the
sinus well marked but not deep.
[Illustration: /Mactra solidissima./]
^M. solidissima^ is one of the very commonest, if not the
commonest large bivalve of the New England, Long Island, and New
Jersey [pg447] beaches. It is covered with a thin brownish or
straw-colored epidermis, usually more or less worn away in adult
specimens and wholly absent from the dead valves found upon the
beaches. There is a fragile V-shaped cardinal tooth, which is
generally broken away in forcing open the valves; the lateral teeth
are long and thin, and striated on their receiving surfaces. The
length of this "giant clam" is from four to seven inches. This is
the first shell the collector will find (north of Hatteras) when he
goes to an open, sandy beach.
^M. similis.^ A small variety of the species last described, of
similar outline, but less heavy and strong. Its range is from
Hatteras southward to Brazil. Passing from New Jersey to Hatteras,
/Mactra solidissima/ diminishes in size, and after passing that
faunal barrier the Northern form is entirely replaced by this
Southern variety. The shell is brighter, though not exactly
bright-shining. Its habits are entirely similar to those of the
Northern form. On the west coast of Florida it is the most abundant
bivalve upon the beaches.
^M. ovalis.^ A species of Northern range, which so greatly
resembles /M. solidissima/ as to suggest identity; but the lateral
teeth are smooth and not striated, while the shell itself seldom
attains a length of over four inches.
^M. lateralis.^ An exceedingly common shell, found in all the
salt-marshes and tidal estuaries of our coast. It is much smaller
than the mactras just described, being not over one half of an
inch in length. It is white, and is covered with a dirty brown
epidermis; the hinge is strong, with deep cartilage fossette and
a V-shaped marginal tooth. The laterals are long and slender. The
animal has a strong foot and two slender, long siphons which are
yellow in color.
[Illustration: /Mactra lateralis./]
GENUS ^Ræta^
^R. (Labiosa) canaliculata.^ In this species the cartilage fossette
is the same as in /Mactra/; the marginal teeth are feeble, and
there are no laterals. The shells of /Mactra/ which we have
examined are heavy or at least solid, but /Ræta/ is thin and
fragile; it is pure white in color and is gracefully ornamented by
concentric raised ribs. The shell is inflated and gapes slightly
posteriorly; it is shining white within and is deeply grooved
concentrically in accordance with the external ribs. Length two
and a half, height two inches. From Hatteras to Mexico, this is
one of the commoner beach shells, but since, as in some other
species already named, the hinge ligament and teeth are feeble, the
valves become separated by the buffeting of the waves, and are cast
disjointed and singly upon the beaches. (Plate LXXXI.)
FAMILY ~VENERIDÆ~
In many respects this is the most distinguished pelecypod family.
It is the largest in number of genera and species, is of world-wide
distribution, and supplies to hungry man a number [pg448] of
comestible species. Several of its genera have been named after
various goddesses and nymphs on account of the great beauty of
their shells. But from a purely biological point of view also the
/Veneridæ/ have claims to distinction, for they seem to represent
about the highest type of shell-development among the bivalves. The
test is extremely hard and often porcelanous. It is solid without
being ponderous and unwieldy in the sense of causing the animal to
be helplessly overburdened by the sheer weight of its shell. The
valves are equal and have three stout cardinal teeth. The foot is
strong, the animal is active, the siphons are free or partially
united, and the gills are more or less crumpled and folded. There is
a compactness and well-regulated arrangement of the organs in the
/Veneridæ/, which impress one who has examined the anatomy of many
pelecypods much as a well-built, efficient, and space-economizing
machine would impress a mechanic. None of the organs are weak or
crowded out to furnish room for the undue or awkward development
of other organs. A good balance is preserved between them all, the
result being a high type of pelecypod.
If we do not expect to find any of the more remarkable forms of the
/Veneridæ/ upon our shores we shall be the less disappointed when
returning from collecting-expeditions. Nevertheless, there are a few
species of /Cytherea/, /Dosinia/, and /Tivela/ in North American
waters which are very handsome shells; but those of our species which
are included under the generic name /Venus/ are in point of beauty
not worthy of their promising name.
GENUS ^Venus^
^V. mercenaria.^ This is the common "hard-shell clam," the "Little
Neck" of the hotels and restaurants, with which every one in New
York and New England is familiar. The species ranges from Cape
Cod to Florida, and occupies two different kinds of station: one
in shallow muddy bays near low-tide mark, in estuaries, etc.; the
other the sandy stations in open deeper bays or the open ocean.
Those coming from "outside" have thinner, more delicate shells,
with thin, concentric ribs. They burrow in the sand or mud, or
crawl quite rapidly. The siphons are short and are united almost
to their ends. The mantle is open (save for the siphons), and the
edges are delicately frilled. In the United States this species
is very extensively gathered for the markets. When the oyster
season closes in April, the hard-shell clam comes into vogue, the
season lasting until September or October. The clams are [pg449]
extensively gathered in the estuaries from Cape May to Cape Cod.
Men armed with rakes drift about in small boats and fish the
sluggish creatures up out of the mud. They will live for many days
out of water if kept in a cool place. Smaller or immature clams are
better for the table, since they are not so tough as their elders.
A few features of the shell of this species are noticeable—the
rather prominent umbones directed forward, the heart-shaped lunule,
the external ligament, the concentric sculpturing of growth-lines,
the pure-white interior (with occasionally violet zones about
the muscle-scars and margin), the three stout cardinal teeth,
the sharp-angled pallial sinus, and the ventral margin finely
crenulated within. The greatest length is about three inches and
the height two and a half inches, but these dimensions exceed those
of the clams usually served upon the half-shell. /V. mercenaria/
ranges into Florida, increasing in size and bulk as it meets the
warmer waters of the Gulf Stream. The Floridian form has received
the varietal name of /mortoni/. This massive clam sometimes weighs
five pounds, and is fully six inches in diameter. Aside from its
great size and thickness, the characters of the shell are wholly
those of the smaller Northern form. It is abundant in shallow,
muddy, brackish bays, and is gathered by men who "tread out" the
clams, feeling for them in the mud and sand with bare feet. The
flesh is tough and disagreeably strong, yet the natives appear to
relish it, especially when it is made into a chowder.
[Illustration: /Venus mercenaria/, typical form.]
^V. cancellata.^ The most abundant species of /Venus/ in Florida,
particularly near Tampa and on the west side. It preserves all the
characteristics of the genus, and is decorated with a series of
high, narrow, concentric ridges, between which are much smaller and
more numerous radiating riblets. The color is dirty white to light
yellow-brown without, and white and violet within. There are three
cardinal teeth and no laterals. The lunule is heart-shaped; the
posterior margin is broadened into a wide, concave area into which
the concentric ridges do not pass. Length one to one and a fourth
inches; height the same. Sometimes the beaches in Florida will in
places be banked up with the valves of this very abundant /Venus/.
As they live in shallow water upon sandy stations, they are easily
dislodged by the heavy storms which sometimes sweep that usually
placid coast. (Plate LXXXII.) [pg450]
GENUS ^Cytherea^
^C. (Callista) gigantea.^ One of the most beautiful Floridian
shells. It is nearly or quite six inches long and about three and
a fourth inches in height. The shell is porcelanous, is covered
with a pinkish, livid epidermis, and is decorated with numerous
longitudinal color-rays of lilac. The rays are usually broken and
interrupted. Within it is china-white, and has a deep pallial
sinus. It is very abundant on the west coast of Florida, at Sanibel
Island, Egmont Key, Lake Worth, and on beaches. (Plate LXXXII.)
^C. maculata.^ This species is more oval in outline than the last.
It is of a fawn-color, blotched or waved with violet-brown, and
is porcelanous and shining. The epidermis is also shining and
corneous. Within it is china-white in color. The pallial sinus is
very deep and wide. Length two and a half to three inches; height
one and a half to two inches. This also is a shell to be looked for
upon the beach after storms, but it will probably not be seen on
the east coast of Florida, although it occurs on the Keys and also
at Hatteras. Both of the species have been used as food, but not
very extensively. The flesh is not lacking in tenderness, but it
has a peppery taste. (Plate LXXXII.)
GENUS ^Dosinia^
There are two species of this very graceful genus of /Veneridæ/
south of Hatteras, ^D. discus^ and ^D. elegans^. These dosinias
have united siphons. The foot is very large and strong, and the
mantle margin is both papillaceous and plicated. The shells of
these two species are about three or three and a half inches in
length and of the same height, and are very flat. The ventral
margin is almost a perfect circle, and the beaks are small and
pointed. The lunule is small and cordate; the valves are very
gracefully sculptured in fine, regular, impressed, concentric
striæ, which are finer and less elevated in /D. discus/ than in
/D. elegans/; the shell is porcelanous and white, and is covered
by a straw-colored, very fine, transparent epidermis. Within, the
strong cardinal teeth are placed upon a long fossette. There is a
deep pallial sinus. /D. discus/ is characteristic of the east coast
of Florida, while /D. elegans/ is only found upon the west side of
the State. Both may be looked for upon the beach, though living
specimens must be captured with the dredge. (Plate LXXXII.)
[Illustration: PLATE LXXXII. Venus cancellata. /Cytherea/
(/Callista/) /maculata/. /Cytherea/ (/Callista/) /gigantea/. Dosinia
discus.]
GENUS ^Tivela^
The coast of California is also favored by the /Veneridæ/, a number
of large species belonging to several genera being present.
[Illustration: PLATE LXXXIII. Tivela crassatelloides, one half
natural size. Chione succincta. Tapes laciniata, one half natural
size. Chione simillima.]
^T. crassatelloides.^ Perhaps the largest and finest of the
California species. It is so common in its between-tides station
that it used to be collected by plowing a furrow through the
sand, the big shells being thrown out upon either side like
potatoes. The shells attain a length of five and a half inches,
and are porcelanous, thick, and heavy. The margins of the valves
are also thick and rounded. The exterior is perfectly smooth,
yellowish-white in color, and decorated [pg451] with purplish
rays arranged in various groupings; over all is a glossy epidermis.
The hinge-teeth are very strong, and a prominent anterior lateral
tooth on the left valve is noticeable. There is an external
ligament; the pallial sinus is well marked, but not very deep.
(Plate LXXXIII.)
GENUS ^Chione^
There are three species on the west coast. This genus is very closely
allied to /Venus/, and is considered by many to be only a subgenus of
the latter. All three species are white, solid, heavy shells which
exhibit the same scheme of sculpturing, namely, numerous longitudinal
ribs crossed by larger and less frequent concentric ridges.
^C. simillima^ is shaped almost exactly like the east-coast /Venus
cancellata/, but its concentric ridges are very numerous and sharp.
There is a strongly marked cordate lunule, and hardly any pallial
sinus. Length one and a half to two inches. (Plate LXXXIII.)
^C. succincta^ has fewer concentric ridges and has a large lunule.
There are purple zones within and touching the heavy cardinal
teeth. Length two and a half inches. (Plate LXXXIII.)
^C. fluctifraga^ has broad but flatter or well-rounded (not sharp)
concentric ridges, no lunule, a small ligament, a fairly deep
pallial sinus, and a finely crenulated margin (within) all around
the valves, except when interrupted by the hinge ligament. The
shell is solid and shining, and marked by deep-purple zones within.
Length one to two inches. Found in southern California.
GENUS ^Tapes^
This is a prominent genus of the /Veneridæ/. Its chief feature is
the total want of lateral teeth. There are several large species in
California.
^T. staminea, T. laciniata.^ These are the most noticeable
species. The former is sold in the San Francisco markets as the
"hard-shell clam." The shell of this species is from two to three
inches in length and of somewhat less height, rounded, and heavy.
The sculpturing consists of radiating ribs traversed by strongly
marked growth-lines. The teeth are strong, and the pallial sinus
is deep. /T. laciniata/ is much like the last, but its surface is
reticulated by a crisscross design that is very striking. It also
has a deep pallial sinus. These two species are of Southern range.
They burrow in gravelly places, among stones, between tide-marks,
and their presence may frequently be detected when walking along
the beach at low tide by seeing a sudden jet of water ejected from
a little hole in the mud or gravel. The animal, becoming alarmed at
the approach of something, suddenly snaps shut its valves, and thus
forces out some water through its siphons. The foot is very strong
and often byssiferous in this genus. (Plate LXXXIII.) [pg452]
GENUS ^Saxidomus^
^S. nuttallii.^ The last of the larger west-coast /Veneridæ/ which
we shall examine. The genus is very closely allied to /Tapes/, and
no doubt might better be considered as its subgenus. The shell is
brownish-white, three to four inches in length, and heavy, rough,
and coarse-looking, with irregular concentric ridges. There is
no lunule, but a large external ligament is very prominent just
back of the beaks. Within it is white, with a deep pallial sinus.
Just below the ligament area is a zone of translucent, agate-like
shell-structure. This large clam, with several others of the same
genus, lives in shallow water near shore.
FAMILY ~PETRICOLIDÆ~
GENUS ^Petricola^
^P. pholadiformis.^ Along the Jersey coast, especially about
Atlantic City, there are small patches of clay or hard tenacious
mud which lie just at the edge of the sea. As the beating of
the surf gradually encroaches upon these hard fragments of once
extensive clay-beds, many specimens of this curious bivalve mollusk
are washed out from their burrows in this clay and cast upon the
sandy beach. The animal has long siphons which are united about
one third of the way to their ends. Although this creature is
allied to the /Veneridæ/, the degree of mantle fusion present is
much greater, leaving in this case only a fairly long slit through
which the foot may protrude. The shell is very dissimilar to that
of any of the /Veneridæ/, and in many respects, judging from a
conventional standard, is a remarkable form. It is exceedingly
thin, is of a chalky texture, gapes widely posteriorly, and is
ornamented with transverse ribs, which are feeble upon the long
produced posterior portion of the shell, but strong in the anterior
part, where they are crossed by the coarse lines of growth, which
appear like vaulted scales upon the ribs. The color is a dull
white. There are two cardinals in each valve and no laterals.
Length one and a quarter to two and a half inches; height one half
to three quarters of an inch. This species passes its entire life
in the burrow it has made for itself in the clay. Its only motions
are made in climbing to the entrance of its burrow or in retreating
far out of sight within its depths. Its siphons are tipped with a
dark or drab color as a measure of protection from the predaceous
crabs which range about the mud surfaces near tidal marks, and are
always upon the lookout for succulent bits of flesh.
[Illustration: /Petricola pholadiformis./]
^P. carditoides.^ A petricola of the Californian coast, very
similar in its habits to the east-coast form. It bores, however,
not only into clay, but also into soft rocks in order to effect a
permanent lodgment. Often this species occupies a hole which it has
discovered already existing; in this case its shell grows to fit
the surroundings. The hinge-teeth, and sculpturing are frequently
reduced and sometimes are quite obsolete; but the shell has the
chalky, thin texture that is characteristic of the genus. [pg453]
There is another family of rock- and mud-boring bivalves which
superficially resemble the petricolas, but their anatomical
organization removes them to a little distance from the
/Petricolidæ/. They are considered further on, under the name of
/Pholadidæ/.
FAMILY ~CARDIIDÆ~
GENUS ^Cardium^
This is another important family of the /Pelecypoda/, which, with
the /Veneridæ/, the /Mactridæ/, and the /Tellinidæ/, is entitled to
distinction on account of its high organization, its high type of
shell, its universal geographical distribution, and its great beauty.
The dominant genus is /Cardium/—a name given on account of the fact
that the shell is shaped like a heart. The animal has a very long,
recurved, and surprisingly strong foot. The mantle-edges are quite
freely open to the siphonal region and are highly papillate and
waved. The siphons are usually very short, but have wide exterior
openings and are also strongly papillate about their margins. The
gills are obliquely situated, and seem to be thicker and heavier
than is usual in pelecypods; they are much folded, the outer lamella
being the smaller. With such a pointed foot and such short siphons
/Cardium/ is obviously not a deep-burrowing genus; but it does
partially bury itself in soft semi-liquid sand. Its progression is
effected by leaps which it is enabled to make by reaching far out
with its foot, then suddenly twisting to one side and throwing the
shell several inches. The shell is ventricose, is closed or gapes
slightly posteriorly, and has prominent subcentral umbones and an
external ligament. The sculpture-scheme of /Cardium/ (if the shell
is not perfectly smooth) is one of radiating ribs or ridges, which,
being regular, form a perfect crenulation of the ventral margin.
There are two cardinal teeth in the center, and one lateral tooth
upon both the anterior and the posterior side: the latter are
situated at some little distance from the beaks.
^C. magnum.^ The largest and finest "cockle" of the east coast of
the United States. It is, indeed, one of the finest cockles in the
world. The almost perfect heart-shape is striking. The posterior
side is somewhat flatly depressed. The thirty-three to thirty-seven
regularly disposed, broad, radiating ribs; the regularly crenulated
margins; the yellowish-brown color garnished with transverse rows
of chestnut or [pg454] purple lines or spots; the brownish-purple
posterior area—all combine to make this large /Cardium/ a
beautiful species. Its length is four inches; height five and a
quarter inches. It is a very abundant species on the open Florida
beaches, where it is often left exposed and alive at very low
tides. (Plate LXXXIV.)
^C. isocardia.^ This also is a Floridian species, of elongated
heart-shape and with radiating ribs. It is not more than half
as large as the last-described species. The ribs are decorated
with erect vaulting scales which are exaggerated portions
of growth-lines. The beaks are smaller in proportion than
in /C. magnum/. The shell is brown to straw-color, stained
with purplish-brown without, and has a bright salmon-red or
purplish-pink interior. The margins are deeply crenulated. The
teeth are arranged as in the last-described species. It is very
common on the beaches of western Florida. (Plate LXXXIV.)
^C. serratum^, ^C. lævigatum^. These two species have a perfectly
smooth surface, and inflated, globose, heart-shaped shells, and
are of a creamy-white color, suffused with a yellowish, golden
tint which suggests the color of butter. Some forms are shiny, and
citron-yellow and pinkish toward the margins, whence the name of
"peach-shell." Height one to two inches. Not uncommon upon Florida
beaches. (Plate LXXXIV.)
^C. mortoni.^ Another of the smooth forms of /Cardium/ (placed in
the subgenus /Lævicardium/). It occurs in Florida and also extends
up the coast to Cape Cod, being very abundant in Long Island Sound.
In the neighborhood of Martha's Vineyard and along the north shore
of Long Island this very pretty little species has been reported as
occurring in soft ground even above low-tide mark, near the mouths
of creeks. It is enough to say of it that it is a smaller edition
of /C. lævigatum/ and may be further distinguished by a purple
blotch on the posterior margin, just within the valves, the general
color within being bright yellow. In young specimens, zigzag lines
of dark fawn-color upon the pale-yellowish background of the smooth
exterior surface of the shells are a noticeable feature. The
largest specimens measure an inch in length and nearly the same in
height. The long cirri upon the siphons are striking.
[Illustration: /Cardium mortoni/, showing extended animal.]
^C. substriatum.^ A cockle of this inflated, smooth type, which
strongly resembles the east-coast form, found upon the Pacific
coast. The name indicates that it is not altogether smooth, a
fact only revealed, however, by a magnifying-glass. It is about
one half of an inch in length, and of a light drab-color, spotted
and sometimes radially lined with yellowish-brown. Professor Keep
likens this species in both shape and color to a sparrow's egg.
(Plate LXXXIV.)
[Illustration: PLATE LXXXIV. 1, Cardium magnum, much reduced. 2,
Cardium isocardia. 3, Cardium lævigatum. 4, Cardium substriatum,
enlarged. 5, Cardium corbis (young specimen). 6, Glycimeris
generosa.]
^C. elatum.^ A veritable giant among the cardiums. It is found on
the southern Californian coast, though rarely north of the Mexican
border. It is of the smooth, glossy type belonging to the subgenus
/Lævicardium/. It attains a diameter of six inches, and is of a
creamy-yellow appearance.
^C. corbis^, ^C. quadrigenarium^. These two Californian cockles
are of the ribbed type displayed in the eastern /C. magnum/ and
/C. isocardia/. /C. corbis/ is found in the northern Californian
and Puget Sound region, [pg455] and /C. quadrigenarium/ on
the southern shores of California. The former is a full, round,
heart-shaped shell with about thirty somewhat scaly ribs. The edge
of the shell is deeply toothed; the color light brownish; the
diameter from two to three inches. It preserves all the features
of the genus as regards both shell and anatomical characters. The
other species, /C. quadrigenarium/, very strongly resembles /C.
magnum/ in size and shape. It lacks the flattened area on the
posterior portion of the shell which is characteristic of the
east-coast species, and its uniform brownish-white coloration is
less striking. It has about forty regularly spaced, radiating ribs,
which are smooth upon the umbonal region, but elsewhere are armed
with spiny processes. Diameter about six inches. (Plate LXXXIV.)
[Illustration: /Cardium islandicum./]
[Illustration: /Cardium pinnulatum./]
^C. islandicum^, ^C. pinnulatum^. Both of these are cold-water
species and occur along the New England coast. The former has
a shell which varies from one half of an inch to two inches in
length, and has from thirty-six to thirty-eight sharp, three-sided,
radiating ribs, the furrows between them being rounded and wrinkled
by growth-lines. A yellowish-brown epidermis covers the shell and
bristles into a sort of fringe upon the sharp edges of the ribs.
/C. islandicum/ cannot be said to be a very common species in New
England, although collectors have so reported it. Specimens from
Massachusetts are not as large as those of more northern habitat.
It does not occur south of Cape Cod. /C. pinnulatum/ is one of the
"small fry" among the cockles. Its largest diameter is less than
one half of an inch; but what it lacks in size it seems to endeavor
to make up in abundance, for it is scattered everywhere along the
coast from New York northward. Specimens can nearly always be found
in the stomachs of fishes, which, by the way, form an excellent
hunting-ground for rare species of mollusks of small size. There
are twenty-six slightly rounded ribs, with deep linear grooves
between them. Upon the ribs, especially in the posterior portion
of the shell, are arched scales, folded so as to appear like blunt
spines. The species may easily be distinguished from the young of
/C. islandicum/ by the smaller number of ribs. The animal, /C.
pinnulatum/, is said to be exceedingly lively and able to make
rapid progress over gravelly bottom by executing sudden leaps.
It has a long, recurved, very strong foot, and its movements are
effected as described above. It is abundant at Bar Harbor. [pg456]
FAMILY ~MYIDÆ~
GENUS ^Mya^
In this family we encounter, rather suddenly, some new features not
heretofore seen in the pelecypod structure. In the first place,
the siphons are enormously large, are united, and are surrounded
by a leathery epidermis. The mantle-edges are fused together along
the entire ventral margin, except for a small slit through which
the foot may project. Although the animal may withdraw the long
siphons into its shell, yet they remain to a certain extent exposed,
for the valves gape widely posteriorly, and only slightly less
so anteriorly. In the economy of these forms the shell seems to
play a less important part than it does in the /Veneridæ/, in the
/Tellinidæ/, and generally in those families whose shells are strong
and, closing firmly, afford the animal within a real protection. The
shell of /Mya/ (the principal genus) is thin, white, and of a softer
chalky texture; it gapes widely "fore and aft," and has a loosely
constructed hinge apparatus, consisting of an erect projecting tooth,
which fits into a pit in the opposite valve.
[Illustration: /Mya arenaria./]
^M. arenaria.^ This is the common "soft-shell clam" of New England.
Its range is from Cape Cod to Greenland and Great Britain. Upon
the Maine coast it is very extensively gathered and sold to the
Banks fishermen for bait. Its use as food for man is probably not
very great, yet it is always to be seen on sale in the markets of
New England coast towns. It cannot compare in flavor with /Venus
mercenaria/, the "hard-shell clam" south of Cape Cod. /M. arenaria/
lives between tides in muddy, sandy, pebbly, or even rocky ground,
where it can find material in which it can burrow and hide itself.
It lies just below the surface, with its siphons projected into
the water. When the water recedes, /Mya/ draws in its siphons
and awaits the return of the tide, every now and then [pg457]
ejecting a jet of water into the air. The shells vary considerably
in size and thickness of valves. Large specimens are three and a
half inches long and two inches high. Our forefathers were not
always well posted upon the habits of mollusks, even though they
may have relished them in chowders and believed their flesh to
possess valuable curative properties. John Winthrop, in 1634, gave
a list of useful American animals, in which he remarked: "Clam,
white; their broth is most excellent in all intermitting fevers,
consumption, etc. These clams feed only on sand." What marvelous
digestive powers!
[Illustration: /Mya arenaria/, showing extended animal.]
FAMILY ~SOLENIDÆ~
[Illustration: /Ensis directus/, showing extended animal: 1, foot; 2,
siphons; 3, papillæ, enlarged.]
In this family are included the long, slender bivalves commonly
known as "razor-shells." Every one who has been to the sea-shore has
become familiar with these odd-looking mollusks, for their valves
are always to be found upon every beach. Their station is upon sandy
flats or bars more or less exposed at low tide. They burrow into
the sand perpendicularly to a depth of two or three feet, remaining
hidden most of the time. Occasionally a colony of them will be seen,
each one projecting slightly from his burrow. If approached most
cautiously some of them may be captured, but if the sand is jarred
they all take fright and disappear in an instant. It is no easy
matter to capture a "razor" when once he has taken warning, for he
will dig down into the sand about as fast as one can follow with a
spade. A good way to catch one is to approach his burrow carefully,
and then plunge a spade obliquely down below him, thereby [pg458]
cutting off his retreat. So tenaciously will they cling to the sand
by expanding the muscular foot that the shell may be pulled entirely
off the body before they will let go.
GENUS ^Ensis^
^E. directus^ (^Solen ensis^, ^Ensis americanus^). The common
species upon the New England and Jersey coasts. The foot is long,
and protrudes from one end of the long shell; it is also very
strong, and capable of change at will into almost any form, from a
pointed bulb to a flat disk. The siphons, which project from the
opposite end of the shell, are short and are not united. The gills
are long. The juxtaposition of these organs is at first confusing,
because the greatly elongated form of the shell and the habits of
the animal in burrowing vertically into the sand have caused the
foot to be pushed farther away from the posterior portion of the
shell and to protrude in a direction just opposite to the siphons.
The shells are bent or slightly curved; they gape at both ends; and
they are fitted with very small interlocking teeth at the upper
corner of the posterior end. The color is white, but a yellowish or
greenish glossy epidermis covers the entire test. Length about six
inches. The manner in which the animal makes its rapid descent into
the sand is very interesting. First extending the foot lengthwise
into a point, it plunges it into the sand; then, by forcing water
into the organ it expands it, thus pushing away the sand on all
sides; and still further expanding the foot at the end into a disk,
it secures an anchorage which enables it to draw down its shell. By
quick repetition of this process /Ensis/ can get out of sight in a
remarkably sudden manner.
[Illustration: /Ensis directus./]
GENUS ^Solen^
^S. viridis.^ A smaller species, about two inches in length, and
with a nearly straight light-green shell. It is often abundant from
New Jersey southward.
^S. sicarius.^ The common Californian species of Northern range. It
is only about two inches long, and is rounded anteriorly, but is
chopped off squarely behind. It is slightly curved and white, and
has a glossy brown epidermis.
^S. rosaceus.^ Another species of Southern range, very similar
in form to the last, but straighter and rosy-white in color. The
epidermis is glossy brown. Length two inches. [pg459]
GENUS ^Tagelus^
^T. gibbus.^ The extended range and shore station of this
exceedingly abundant species will cause it to be among the first
accessions to the cabinet of the collector south of Cape Cod. It
burrows deep in sand and mud, leaving two small openings to the
hole for the accommodation of its two excessively long siphons.
As in /Solen/ and /Ensis/, the foot is large and muscular,
tongue-shaped, and capable of remarkable change of form and great
freedom of movement. The long white siphons, separated from the
base and each provided with orange-colored eyes (or, rather, a
rudimentary sort of visual organs), are the most important feature.
The apex of the hinge is not, as in /Solen/ and /Ensis/, at the
end of the shell, but is more conventionally placed near the
middle; the cardinal teeth are very small, two upon each valve
and interlocking; a flat, oblong, callous process serves as a
fossette. The dorsal and ventral margins are parallel, and gape
at both ends; the shell is white, and is covered with a dense
yellowish epidermis, which, passing the ventral margin, appears to
become continuous with the thickened mantle-edge. There is no other
species north of Hatteras with which this could be confounded.
The double entrance to the burrow, which may be discovered about
low-tide mark, is unique. /T. gibbus/ is a good species to examine
for the crystalline stylet in the digestive tract.
[Illustration: /Tagelus gibbus/, showing extended animal.]
[Illustration: /Tagelus gibbus./]
FAMILY ~GLYCIMERIDÆ~
GENUS ^Glycimeris^
^G. generosa.^ A large shell of the Pacific coast, occurring
most abundantly in Puget Sound waters, where it frequents muddy
shallows. It is a remarkable pelecypod in respect to its siphons
and the degree of mantle fusion. The appearance of the animal
is that of a huge pair of [pg460] united siphons, protected
laterally at their larger end by two white, widely gaping valves.
The very small pedal opening in the line or mantle juncture
indicates a very small foot. (Plate LXXXIV.)
FAMILY ~PHOLADIDÆ~
There is a striking resemblance between the shells of this
rock-boring family and those of the petricolas—a resemblance which
consists principally in the texture of the shell and the tendency
to different types of sculpturing upon the posterior and anterior
surfaces of the valves.
GENUS ^Pholas^
In /Pholas/ the anterior part of the hinge-margin is reflected back
over the umbones, and a long rib-like tooth springs from under the
umbonal region and curves out almost to the center of the valves.
The shell gapes "fore and aft," and is thin, white, very hard, and
brittle. The animal has a short, truncated foot and a small orifice
in the mantle through which the foot may be projected. The siphons
are long and are united almost to their ends. Dorsally, an exposed
portion of the animal is protected by accessory calcareous plates.
The habits of /Pholas/ are very interesting. It is found in holes
gouged out of solid rock or out of pieces of wood; sometimes, like
/Petricola/, it may be found excavating in hard clay. As the anterior
end of a /Pholas/ shell is the larger in diameter, and is the end
which is most deeply buried in the rock (the opening of the burrow
being comparatively small), there was some mystery as to the way
in which the creature manages to get inside its rocky dwelling.
Observations in aquaria have shown that the young /Pholas/ begins his
process of home-building very early in life. The wearing away of the
stone is effected by constantly turning the shell around, scraping
with the anterior edges of the valves. A lodging-place having been
secured, /Pholas/ is obliged to work constantly to enlarge his burrow
for the accommodation of his growing shell. The long siphons may
project from the hole and draw in food and breath, but the animal is
a prisoner for life. When /Pholas/ has withdrawn his long siphons
he is reasonably secure from his enemies, but [pg461] nevertheless
thousands of them are destroyed by predatory starfishes, who know
how to get at their victims. The restless crustaceans, ever on the
outlook for a meal, often nip the siphons of the rock-dwellers, and
a kind of worm sometimes attacks them, and, destroying the animal,
proceeds to occupy the empty shell and burrow.
^P. costata.^ This species has a wide geographical range, being
found from Cape Cod to South America, but it is not abundant north
of Hatteras. In Florida it burrows deep in sand as well as in wood
or rock. On account of its white color and suggestive shape and
sculpture, it has received the popular name of "angel's-wings." It
grows to a length of seven or eight inches.
[Illustration: /Pholas costata./]
^P. truncata.^ This has much the same range as the last, but is
more commonly to be found in New England waters. It also burrows
in any hard substance, or in mud above low-water mark. It is
especially common in peat-banks.
[Illustration: /Pholas truncata./]
^P. californica.^ A Californian /Pholas/. The shell is about three
inches in length, and resembles in all features and habits the
/Pholas/ of the east coast. Differences in the shell indicate that
it is a distinct species.
GENUS ^Zirphæa^
^Z. crispata.^ A species of Northern range, occurring but sparingly
in New England, in hard clay or rocky burrows. It may be identified
at once by the furrow which passes from the beaks across the valves
to the lower edges of the shell and divides the surface of the
valve into two areas. The anterior area is decorated with radiating
toothed ribs; the posterior area is smooth. This conchological
feature of the genus is very [pg462] curious; it may be observed
also in several deep-sea genera and in certain extinct fossil
forms. The length of this shell is about two inches. This species
also occurs in California, where its favorite station is in hard
tenacious clay. Length two to four inches.
[Illustration: /Zirphæa crispata./]
FAMILY ~TEREDINIDÆ~
GENUS ^Teredo^
^T. navalis.^ This species is worm-like in form, but it has a small
bivalve shell at the larger end, and near the anterior extremity
two calcareous appendages called pallets, beyond which extend two
siphons. Along the surface of the mantle is secreted a continuous
shelly tube which lines the burrow. This mollusk, commonly called
the "ship-worm," is exceedingly destructive, perforating with its
burrows submerged timber and soon rendering it useless. Various
means are taken to protect ships, the piles of wharves, buoys, and
the like, against its ravages; copper sheathing, large-headed nails
driven close together into the wood, verdigris paint, and so on,
being used with more or less effect. Vast numbers of these animals
enter the wood and burrow in various directions, but they never
interfere with one another, a thin partition of wood always being
left between adjacent burrows. How they effect the burrowing is
not determined, but it is supposed to be by means of the pallets.
/Teredo/ does not, like the boring isopod /Limnoria lignorum/, feed
upon the wood. Its food consists of microscopic organisms which
are taken in through the incurrent siphon. In temperate waters /T.
navalis/ grows sometimes to the length of six inches; in tropical
waters it attains the length of two feet.
[Illustration: /Teredo navalis/, in a piece of timber: /P/,
pallets; /SS/, siphons; /T/, tube; /V/, valve of shell.]
There are three other species of /Teredo/ and one of the genus
/Xylotrya/ on our Northern shores; /T. navalis/ is, however, the
most common and most destructive. In Southern waters there are many
other forms of these boring mollusks. [pg463]
FAMILY ~PANDORIDÆ~
GENUS ^Pandora^
[Illustration: /Pandora trilineata./]
^P. trilineata.^ A little New England shell, remarkable on account
of its extreme flatness. When looking at this shell before opening
it, one naturally wonders where the animal finds room to exist
between two such disk-like valves. The animal is very thin, with
largely united mantle-edges, widely separated feeble adductor
muscles, and a fairly large tongue-shaped foot. The shell is
nacreous, rounded anteriorly, and produced posteriorly into a sort
of upturned tip which gapes to accommodate two little siphons. The
dorsal hinge-margin is excavated and curved. Length about one inch.
It is abundant at Cape Cod, in sandy stations, on oyster-beds, and
is found from Maine to Florida. [pg464]
TABLE SHOWING THE CLASSIFICATION OF THE CEPHALOPODS DESCRIBED IN THIS
CHAPTER
CLASS =CEPHALOPODA=
Orders Genera Species
Subclass =Tetrabranchiata=
^Nautilus^
Subclass =Dibranchiata=
~OCTOPODA~ ^Octopus^
^Argonauta^ ^A. argo^
~DECAPODA~ ^Spirula^
^Ommastrephes^ ^O. illecebrosus^
^Sepia^
^Loligo^ ^L. Pealei^
^L. brevis^
CLASS =CEPHALOPODA=
The /Cephalopoda/ form a singularly isolated group, and are so
superior in organization and intelligence to all other mollusks
that it is difficult to believe that they are first cousins to the
lethargic gasteropod and the simply constructed bivalve. But the
class bears the stamp of its origin in a mantle, a radula, and a
disposition of internal organs and functions which, although highly
perfected, is essentially molluscan.
Along the Atlantic coast of the United States, particularly in its
northern portion, occur several examples of cephalopods belonging to
the genera /Ommastrephes/ and /Loligo/, all the species of which are
referred to, in common parlance, as "squids." They frequent shallow
water, and are often to be found in weirs, darting about with rapid,
spasmodic movements, or perhaps lying motionless on the bottom.
The squids enter the weirs for the purpose of capturing the young
mackerel which are caught in these traps. The squid lies quietly upon
the bottom, which it simulates so closely in color as to be almost
invisible, and when [pg465] a school of fishes swims over it, darts
suddenly into the midst of it, seizes a fish with its sucker-bearing
arms, and kills it by the bite of its parrot-like beak or jaws.
Sometimes it happens that squids, while pursuing fish too near shore,
precipitate themselves upon the beach, where they flounder about,
ejecting water from their siphons, which pushes them only farther
away from the water, and squirting out "ink" from their ink-sacs in
a vain endeavor to hide themselves from view. On bright moonlight
nights squids often go ashore in vast numbers, and perish within a
few inches of their native element, which they seem to be unable
to regain. These creatures usually swim backward, and the theory
is that, dazzled by the bright light of the moon, they continue to
gaze at it while swimming, and if there happens to be a shore in the
direction of their movements, they suddenly find themselves beached.
The fishermen of Canada and New England take advantage of this habit
and capture great quantities of squids by placing bright lights in
the bows of their boats and then rowing toward shore, thus driving
the squids out of the water. The Banks fishermen use them as bait
for catching cod. The right claimed by American fishing-schooners to
purchase squids in Newfoundland has helped to keep alive the quarrel
between Canadian and American fishermen, which has vexed their
respective governments for many years.
The range in size among the species of this class is very remarkable.
The little sepiolas are about an inch long; the squids of our
coasts vary in length from eight inches to one foot; and the giant
/Architeuthis/ of the North Atlantic measures, often, fifty feet
from the end of its arms to the tip of its tail. Such a creature,
with its long arms provided with suckers, its powerful jaws, and its
rapid, alert movements, is a formidable foe. These animals have been
the basis of many legends about sea-serpents and sea-monsters. A
gruesome story of an octopus is told by Victor Hugo in "The Toilers
of the Sea," where he gives a thrilling account of a man's encounter
with a devil-fish in a cave. One who has read this tale has a vivid
picture in his mind of the giant squid, and the danger of meeting
one of these many-armed foes. Victor Hugo's devil-fish, [pg466]
however, is an animal not true to nature, but a composite, having
the attributes of the polyp and of the octopus, and the name of a
large ray of Southern waters, a real fish, the /Cephaloptera/, known
in its localities as devil-fish. This monstrosity of the novelist's
imagination has, however, done more to acquaint the general public
with these interesting cephalopods than have the descriptions of
scientists.
The giant squid, which is such a dangerous foe, has its own enemy in
the sperm-whale. The cachalot swims through the water with its lower
jaw hanging, the cephalopod grasps the jaw, and the whale then shuts
his capacious mouth upon it. Whalemen describe conflicts between
these enormous creatures, the whale always being the conqueror.
Sperm-whales killed by man often eject great quantities of the squids
in their death throes, showing this food to be almost their exclusive
diet.
The name "cephalopod," meaning "feet around the head," is descriptive
in part of their anatomy. The head is usually marked off by a
neck-constriction, and it bears two highly organized eyes. The foot
is fused in part with the head above the eyes and around the mouth;
on the upper side it is divided into eight or ten long arm-like
processes, bearing suckers, which act as organs of prehension. The
under part of the foot forms a tube called the funnel. Through the
funnel the animal expels water from the mantle cavity, and thus
propels itself through the water.
The mantle covers the body of the animal, and is a cup-shaped or
conical envelope, open only at the anterior end, through which
project the head and siphon or funnel. It is attached to the body by
a line on the dorsal side, the anterior margin being free and open,
but provided with an arrangement of cartilages by which it can be
hooked on to the siphon, thus completely closing the entrance to
the mantle cavity. The mantle is very muscular, and is constantly
expanding and contracting, taking water into the mantle cavity
through the mantle opening for respiratory purposes, or expelling
it through the siphon for propulsion; in the latter case the mantle
opening is closed at the moment of ejecting the water. When the
siphon is in its normal position [pg467] the animal swims backward;
but it can be turned back over the edge of the mantle, giving a
forward movement.
The surface of the mantle is covered with pigment-cells
(/chromatophores/). There are sets of chromatophores containing
different colors. The cells are opened or closed at will by muscular
action of their walls. When open the cells seem to fuse together,
giving a solid color-surface, or spots of color as desired, in blue,
red, yellow, or brown; when closed they seem as specks on the almost
transparent tissues of the animal. Flashes of changing color follow
one another with great rapidity over the living animal. In swimming
it assumes the color of its surroundings.
Another curious means of protection possessed by the dibranchiate
cephalopods is an ink-bag, the brown or black secretions of which are
ejected through the siphon, clouding the water when the animal wishes
to escape from danger. The ink taken from the ink-sac of /Sepia/ is
an article of commerce.
Only /Nautilus/ and the female /Argonauta/ have the characteristic
external shell of mollusks. In all other forms the shell is internal
or is invested in the integument of the mantle. Of such is the
cuttlebone of commerce, which is a calcareous leaf-like body obtained
from /Sepia/, the cuttlefish. The common squid /Loligo/ has a horny
substance situated in the dorsal side of the mantle, called the pen.
/Spirula/ has a spiral internal shell divided into chambers. Vast
numbers of these shells are cast upon the beaches of the Pacific
Islands, and they have also been found on the shore of Nantucket.
Cephalopods are separated into two subclasses. In the first, the
/Tetrabranchiata/, there are four branchiæ, four nephridia, and four
auricles. They are without an ink-sac, and have the foot divided into
lobes bearing sheathed tentacles. /Nautilus/ is the only genus.
SUBCLASS =TETRABRANCHIATA=
GENUS ^Nautilus^
Probably the best-known cephalopod is /Nautilus/—the pearly-shelled,
chambered nautilus made immortal in the beautiful poem of Oliver
Wendell Holmes. The shell of /Nautilus/ is a flat spiral; the
interior is divided by septa forming a series of chambers; [pg468]
the septa are perforated, and through the opening runs a tube or
prolongation of the body, the siphuncle, which extends to the tip of
the shell. The chambers are filled with gas. The animal in the course
of its growth moves forward into a newly formed chamber and builds a
new septum, closing the cavity last occupied. /Nautilus/ lives among
the coral reefs of the southern Pacific. Its four or five species are
the remnants of a once very extensive race of cephalopods. The fossil
remains of many species of /Nautilus/, together with various other
genera of shell-bearing cephalopods, indicate that this group has
seen its best days. The dibranchiate genera, however, appear to have
reached their maximum at the present day.
SUBCLASS =DIBRANCHIATA=
[Illustration: /Argonauta argo/, female removed from shell.]
The second subclass, the /Dibranchiata/, is characterized by two
branchiæ and two auricles. The main part of the foot is divided into
eight or ten long arms provided with numerous suckers arranged in
from one to four rows on the ventral side of the arms. They have
also an ink-sac. The /Dibranchiata/ are divided into two orders: the
/Octopoda/, which have eight arms, and comprise the /Octopus/ and
/Argonauta/; and the /Decapoda/, which have ten arms, and comprise
/Spirula/, /Ommastrephes/, /Sepia/, and /Loligo/. In these animals
two of the ten arms are longer than the others, and these tentacular
arms have suckers only on their broadened, club-like ends, they are
kept retracted within grooves, one on each side of the head, except
when needed for prehension. [pg469]
GENUS ^Argonauta^
^A. argo.^ In this species, the paper-nautilus, the shell, which is
possessed only by the female, is not chambered. The animal rests in
the shell, but has no organic connection with it other than by the
membranous expansions at the extremities of the two dorsal arms,
which secrete it and hold it in place. The purpose of the shell is
to hold and protect the eggs.
[Illustration: /Argonauta argo/, side view of shell.]
GENUS ^Loligo^
^L. Pealei.^ In this species the body is cylindrical, tapers to a
point, and has a flat appendage in front. The fins are terminal,
half, or more than half, as long as the body, united in a point
posteriorly, and obtusely rounded on the outer angles. The head
is a little narrower than the mantle. There are eight sessile,
sub-triangular arms furnished with two series of suckers which
are hemispherical and stalked, and two long retractile tentacular
arms dilated at the extremities, bearing four rows of suckers. It
has a pen- or quill-shaped cartilaginous substance in the dorsal
integument of the mantle. Common from Cape Cod to South Carolina.
^L. brevis.^ A small short-bodied species, with short rounded
caudal fins. It is common from South Carolina to Florida, and
extends as far north as Delaware Bay.
[Illustration: /Loligo Pealei/, young female; dorsal view.]
GENUS ^Ommastrephes^
[Illustration: /Ommastrephes illecebrosus/, young male; ventral view.]
^O. illecebrosus.^ A species similar to /L. Pealei/, but with
shorter fins. These are broad and pear-shaped, one third wider than
they are long, and usually reach less than one half the length of
the mantle. They are straight on the posterior end, and form nearly
a right angle, while the upper margins are rounded. The head is
as broad as the mantle. The arms are stout and taper to an acute
point. The tentacular arms are long when expanded. The species
is abundant from Cape Cod to Newfoundland, and is found as far
south as Newport, Rhode Island. This is the squid which is used so
extensively in the Banks fishery as bait. It [pg470] visits the
shores in large schools, presumably in pursuit of prey, and often
itself becomes the victim. It is a beautiful creature from its
varying colors, which are truly wonderful. It changes in a moment
from vivid red to deep blue, purple, orange, and so on, the colors
often passing over it in flashes as it swims along. [pg471]
VIII
CHORDATA
TABLE SHOWING THE CLASSIFICATION OF THE CHORDATA DESCRIBED IN THIS
CHAPTER
Phylum =CHORDATA=
Class =UROCHORDA= or =TUNICATA=
Order =LARVACEA= (/Free-swimming, pelagic; Tunicata having
caudal appendages/)
Genera Species
^Appendicularia^
Order =THALIACEA= (/Free-swimming Tunicata, without caudal
appendages; single or in colonies; muscles of body-wall
arranged in complete or in interrupted ring-like bands/)
Suborder =CYCLOMYARIA= (/Cask-shaped bodies with complete
rings of muscular bands; oral and atrial apertures at
opposite ends of the body/)
^Doliolum^
Suborder =HEMIMYARIA= (/Spindle-shaped bodies; muscular bands
in incomplete rings; oral and atrial apertures subterminal/)
^Salpa^
Suborder =PYROSOMATA= (/Hollow cylindrical colonies; zoöids
embedded in a gelatinous wall; oral apertures open on
the outer, atrial apertures open on the inner surface of
cylinder/)
^Pyrosoma^
Order =ASCIDIACEA= (/Mostly fixed Tunicata; single or in
colonies; tests of considerable thickness/)
Suborder =ASCIDIA SIMPLICES= (/Possess distinct tests;
usually permanently fixed/)
Genera Species
^Molgula^ ^M. manhattensis^
^M. pellucida^
^M. arenata^
^Cynthia^ ^C. pyriformis^
^C. partita^
^C. carnea^
^Boltenia^ ^B. clavata^
^Ascidia^ ^A. amphora^
^A. callosa^
Suborder =ASCIDIA COMPOSITÆ= (/Fixed colonies; the zoöids
embedded in a common gelatinous material; without separate
tests/)
^Botryllus^ ^B. gouldii^
^Amarœcium^ ^A. pellucidum^
[pg474]
CHORDATA
CLASS =UROCHORDA= or =TUNICATA=
The most conspicuous animals of this class are the ascidians, which
are common objects on rocky coasts. The /simple ascidians/ are
peculiar leathery, sac-shaped bodies which send out jets of water
when touched. This habit gives them the common name of "sea-squirts."
Some are highly colored, especially those of Southern waters; others
are somber, unattractive bodies, often growing in masses. The
/compound ascidians/ are gelatinous colonies, sometimes forming thin
incrustations, sometimes jelly-like masses, on seaweeds, shells,
etc. This class comprises also the beautiful /Salpa/, a genus of
free-swimming animals having transparent bodies encircled by rings of
muscular bands, and in one stage forming chains of attached organisms
which swim on the surface of the sea and of bays.
The tunicates are by some authors classed with the vertebrate
animals because in the larval stage they have a notochord; this
disappears, however, in the adult form, and the animals are
considered degenerates. The tunicates are interesting to biologists
from the remarkable changes they undergo in their life-history, and
(in some genera) the marked phase of alternation of generation. One
of their curious anatomical features is the blood-vascular system.
The circulation is propelled by wave-like contractions of the heart,
which, after forcing the blood one way for a time, stops and reverses
the blood-current. The tunicates are widely distributed, and occur at
all depths. (Plate LXXXV.) [pg475]
GENUS ^Salpa^
[Illustration: /Salpa/ chain.]
The animals of this genus are transparent, subcylindrical, smooth,
gelatinous bodies encircled by bands of white muscular fiber. They
strikingly exemplify alternation of generations. They occur in two
distinct conditions, one being solitary, the other consisting of
animals united in chains. The solitary individuals are about an inch
long, and have two long processes at the posterior end. These single
animals reproduce by budding, and form series of individuals in small
chains, the animals being arranged in two rows. The chains grow to
the length of a foot or more, and contain twenty to thirty pairs
of salpas. Each of these connected individuals produces in turn a
single egg, which becomes a single /Salpa/, and this again, like its
grandmother, reproduces by budding. Thus the animals are alike only
in alternate generations. The naturalist Chamisso, who discovered
the relationship between the two forms, expressed it as follows: a
/Salpa/ mother is not like its daughter or its mother, but resembles
its sister, its grandmother, and its granddaughter. The single zoöids
liberate many colonies during the summer, which grow rapidly, and in
the autumn the chains are exceedingly abundant. The /Salpa/ chains
swim about with a serpentine movement, and are beautiful, delicate
objects with their transparent bodies banded with white, tinged with
pink, and streaked with blue.
SIMPLE ASCIDIANS
These are solitary and usually fixed; they are never free-swimming,
and when in colonies each animal has a distinct test. All the larger
ascidians, or sea-squirts, belong to this group.
GENUS ^Molgula^
Body more or less globular, membranous, attached or free; orifices on
very contractile tubes.
^M. manhattensis.^ Nearly globular when the tubes are contracted;
usually covered with bits of eel-grass, seaweeds, sand, etc.;
surface a [pg476] little rough; color olive-green. The animal is
often attached to rocks, more frequently to eel-grass and seaweeds,
and is sometimes so crowded as to form large clusters. Found from
Maine to North Carolina.
^M. pellucida.^ Body nearly globular, about an inch in diameter,
smooth, clean, and translucent, the intestine showing through the
test. The two tubes are large, swollen at the base, and divergent.
The animal lives free in the sand, and is found from Massachusetts
to North Carolina.
^M. arenata.^ Body somewhat compressed laterally; test thin and
covered completely with sand, which is closely adherent; about
three quarters of an inch in diameter; tubes short and wide apart.
Found on shelly and sandy bottoms of bays and sounds.
GENUS ^Cynthia^
The animal is attached, the body coriaceous, and the orifices
four-lobed. Frequently associated in groups, the individuals often
differing in color.
^C. pyriformis.^ Body globular, or oblong when extended; hard,
velvety, whitish surface, with pink cheeks; orifices on prominent
protuberances on the upper surface. It lives in clear, deep water
on rocks, and is sometimes found at low-water mark on the northern
New England coast. Commonly called the sea-peach. (Plate LXXXV.)
^C. partita.^ Body oblong; attached; test horny and wrinkled;
rusty-brown; apertures square, on prominent tubes marked with
triangular spots of white and purple; diameter one inch. Found on
the piles of wharves and on shelly bottoms in shallow water; also
on the under side of stones when they are much flattened.
^C. carnea.^ Test low and flat, with a thin margin; adherent by a
very broad base; orifices small, square, slightly prominent; red
or flesh-color. Found in deep water on stones and shells on the
northern New England coast.
GENUS ^Boltenia^
Body more or less globular, on a long stem; fixed; orifices on the
side.
^B. clavata.^ Body long, wrinkled, leathery, on a long stalk,
resembling the flower of lady's-slipper (/Cypripedium/); two
cross-shaped orifices wide apart on the side; yellowish in color;
attached to stones in deep water, but sometimes washed ashore in
storms. The stalks are often covered with polyzoans and hydroids.
(Plate LXXXV.)
[Illustration: PLATE LXXXV. ASCIDIANS. 1, Ascidia callosa. 5, Cynthia
placenta. 2, Botryllus Schlosseri. 6, Glandula fibrosa. 3, Cynthia
pyriformis. 7, Cynthia condylomata. 4, The same, enlarged. 8,
Boltenia clavata. 9, Cynthia echinata.]
GENUS ^Ascidia^
Test gelatinous or cartilaginous; attached; it grows in bunches
under stones at low-water mark. Sometimes it is variously [pg477]
colored, but otherwise it is repulsive in aspect. The apertures are
wide apart; one orifice is eight-lobed, the other six-lobed.
^A. amphora.^ Form usually globular, but more or less irregular;
substance something like rubber. Found of all sizes adhering in
clusters to stones, shells, and piles, and usually covered with
marine growths. The color is grayish-brown.
^A. callosa.^ Body depressed, usually oval, but varying in shape;
thick, fleshy, translucent; surface uneven; apertures dark purple
and prominent. Found at low tide adhering to stones and shells.
(Plate LXXXV.)
COMPOUND ASCIDIANS
Ascidians of this group form fixed colonies, and are embedded in
gelatinous material, the animals having a common test, but not being
united by any internal union. The colonies thus formed are flat and
incrusting, or are branched and lobed, or sometimes elevated on
stalks. The zoöids are in some cases dotted irregularly over the
entire surface, in others are in rows, or again are in groups. They
have various colors—purple, yellow, blue, gray, and green. They are
common on eel-grass, the piles of wharves, the bottoms of boats, and
so on.
GENUS ^Botryllus^
^B. gouldii.^ This species forms thick, fleshy, translucent
incrustations, often several inches in length and a quarter of an
inch wide, over eel-grass, the piles of wharves, and other objects.
Sometimes, at the end of summer, small objects are completely
covered with the luxuriant growth of this compound ascidian. The
zoöids form circular or elliptical groups, often as many as fifteen
surrounding each orifice, looking like minute stars. The colonies
vary in color. Often on the same stem of eel-grass will be found
separate colonies varying in this respect. In some the ground-color
will be olive-green specked with white, while the zoöids are
purple, marked with other colors; again the arrangement is quite
different.
GENUS ^Amaræcium^
^A. pellucidum.^ A massive compound ascidian, smooth, translucent,
and gelatinous, which forms large, hemispherical, complex,
irregular masses six inches or more in diameter. It is usually
covered by adhering sand. The mass consists of club-shaped lobes,
which rise from a common base. Each lobe contains a central orifice
around which long, slender zoöids, sometimes an inch long, are
grouped. These masses are so abundant in some places that they
cover the bottom for considerable spaces. They are found in deep
water from Cape Cod to North Carolina. [pg479]
INDEX
Heavy-faced type is used to indicate names of classes, orders,
genera, etc.; heavy-faced numerals to indicate the place where the
fullest description is given
A
Abdomen, 243, =246=.
Abductor muscles, =302=.
Aboral, 202.
Surface, 201.
Abyssal, =23=.
Acalephs, =134=.
=Acanthalithodes=, 240, =271=.
=A. hispidus=, 240, =271=.
=Acephala=, 409.
=Acetabularia=, 51, =57=.
=A. crenulata=, 51, =57=.
=Acmæa=, 9, 309, 312.
=A. mitra=, 324, =357=.
=A. patina=, 324, =357=.
=A. testudinalis=, 41, 42, 324, 343, 348, =356=.
=A. testudinalis=, var. =alveus=, 324, =357=.
=Acmæidæ=, 324, 356.
Acontia, =145=.
Acorn-shell, =254=.
=Actiniaria=, 141, =142=, 143, 144.
=Actinozoa=, 112, 115, 141, =142=.
=Adamsia palliata=, 144, =267=.
Adductor muscles, =302=, 413, 417.
=Æolididæ=, 324.
=Æolis=, 41, 42, 309, 324, =354=.
=Æ. papillosa=, 324, =354=.
=Æquoreidæ=, 116, =128=.
=Ætea=, 188, =194=.
=Æ. anguinea=, 188, /194/.
=Agarum=, 36, 42, 63, 68, =69=.
=Aglaophemia=, =127=.
=A. struthioides=, 116, =127=.
=Ahnfeldtia=, 76, =82=.
=A. plicata=, 76, =82=.
=Alaria=, 63, =69=.
=A. esculenta=, 41, 42, 63, =69=.
=Albunæa=, 240, =269=.
=A. gibbesii=, 240, =269=.
=Alcyonacea=, 141, =151=.
=Alcyonaria=, 141, 142, =150=, 152.
=Alcyonidium=, 189, 192, =197=.
A. hirsutum, 189, =197=.
=A. hispidum=, 189, =198=.
=A. parasiticum=, 189, =198=.
=A. ramosum=, 189, =197=.
=Alcyonium=, 141, =151=.
=A. palmatum=, 141, =150=, 161.
Aleutian province, =311=.
=Algæ=, =25=, =48=, 62, 76.
Botanical facts about, =25=.
Alternation of generation, =120=, 121.
=Amarœcium=, 473, =477=.
=A. pellucidum=, 473, =477=.
Ambulacra, 201, 202, =205=, 214, 218.
Ambulacral groove, 205.
Ossicles, =205=.
Zones, 201, 202, =205=, 218, 229.
American division, =24=.
=Amphictenidæ=, 162, =183=.
=Amphineura=, 300, 316, 317, 320, =321=, 323.
=Amphipoda=, 242, =289=.
=Amphissa=, 312.
=A. corrugata=, 326, =389=.
=Amphitrite=, 161, =182=.
=A. ornata=, 161, =182=.
=Amphiura=, 213, =215=.
=A. squamata=, 213, =215=.
Ampullæ, 201, =205=, 206, 218.
=Anadyomene=, 51, =57=.
=A. flabellata=, 51, =57=.
Anatomy, 20.
Of higher Crustacea, =246=.
Anemone Cave, =40=.
Angel's-wings, 461.
Animal-flowers, =142=.
Animal life in its lowest forms, =21=.
=Annelida=, 305.
=Annulata=, 159, 161, 164, 170.
=Anomia=, 405, =424=.
=A. aculeata=, 405, =425=.
=A. lampe=, 405, =425=.
=A. simplex=, 405, =424=.
=Anomiidæ=, 405, =424=.
=Anomura=, 240, =264=.
Antennæ, 243, =246=, 258.
Antennules, 243, =246=, 258.
=Antheneidæ=, 204, =209=.
=Anthomedusæ=, =116=.
Aperture, =302=.
Apex, 343.
=Aphrodite=, 161, =174=.
=A. aculeata=, 161, =174=.
=Aphroditidæ=, 161, 172, =173=.
=Aplacophora=, 300, 321, =323=.
=Aplysella violacea=, 105.
=Aplysia Wilcoxii=, =352=.
=Aplysiidæ=, 324.
=Apoda=, 228, =233=.
=Appendicularia=, 472.
=Arabella=, 161, =179=.
=A. opalina=, 161, =179=.
=Arbacia=, 217, =222=.
=A. punctulata=, 217, =222=.
=Arbaciadæ=, 217, 222.
=Arca=, 310, 405, =425=.
=A. noæ=, 405, =426=.
=A. pexata=, 405, =425=.
=A. ponderosa=, 405, =426=.
=Arcachon=, 434.
=Architeuthis=, 465.
=Arcidæ=, 405, =425=.
Arctic province, =309=.
=Arctica=, 406, =441=.
=A. islandica=, 406, =441=.
=Arenicola=, 162, 172, =184=.
=A. marina=, 162, =184=.
=Arenicolidæ=, 162, =184=.
=Argonauta=, 464, 467, 468.
=A. argo=, 464, =469=.
Aristocratic genera, 313, 377, 398, 401.
Aristotle's lantern, =203=.
=Arthrocladia=, 62, =67=.
=A. villosa=, 62, =67=.
=Arthropoda=, 238, =244=.
=Arthrostraca=, 242, =289=.
=Articulata=, 188.
=Ascidia=, 473, =476=.
=A. amphora=, 473, =477=.
=A. callosa=, 473, =477=.
=A. compositæ=, 473.
=A. simplices=, 473.
=Ascidiacea=, 473.
Ascidians, 8, 474.
Compound, 474, =477=.
Simple, 474, =475=.
=Ascophyllum=, 63, =73=.
=A. nodosum=, 43, 63, 73.
=Asperococcus=, 62, =66=.
=A. echinatus=, 62, =66=.
=Astacoidæ=, 240, =261=.
=Astarte=, 309, 406, =440=.
=A. castanea=, 406, =441=.
=A. undata=, 406, =441=.
=Astartidæ=, 406, =440=.
=Asterias=, 204, =212=.
=A. Forbesii=, 204, 207, =212=.
=A. gigantea=, 204, 207, =212=.
=A. ochracea=, 204, =212=.
=A. vulgaris=, 43, 204, 207, =212=.
=Asteriidæ=, 204, =212=.
=Asterina=, 204, =210=.
=A. folium=, 204, =210=.
=A. miniata=, 204, =211=.
=Asterinidæ=, 204, =210=.
=Asteroidea=, 200, 204, =205=.
=Astræa=, 141, 146, 147, =148=.
=Astrangia=, 141, =150=.
=A. danaë=, 13, 141, =150=.
=Astropecten=, 204, =209=.
=A. articularis=, 204, =209=.
=Astropectinidæ=, 204, =208=.
=Astrophyton=, 213, =215=.
=A. Agassizii=, 213, =215=.
=Astyris gausapata=, 326, =389=.
=Asymmetrical=, 328.
=Aurelia=, 133, =137=.
=A. flavidula=, 133, =137=.
=Auricula=, =231=.
=Auriculata=, 201.
=Avicula=, 405, =431=.
=A. atlantica=, 405, 431.
=Avicularia=, 190, =193=.
=Aviculidæ=, 405, =430=.
B
=Balanus=, 239, 250, =254=.
=B. balanoides=, 239, =255=.
=B. crenatus=, =256=.
=B. eburneus=, 239, =255=.
=B. geniculatus=, 239, =256=.
=B. ovularis=, =255=.
=B. rugosus=, 239, =256=.
=B. tintinnabulum=, 239, =256=.
=Bangia=, 78, =96=.
=B. fusco-purpurea=, 43, 78, =96=.
=Bangiaceæ=, 78, =96=.
Barnacles, 8, 43, 245, =250=.
Bathymetrical division, 23.
=Bdelloura=, 160, =167=.
=B. Candida=, 160, =167=.
=B. rustica=, 160, =167=.
Beach-flea, 245, =289=.
Beak, 417.
=Bela=, 309.
Benthos, =23=.
=Beroïda=, 154, =157=.
Bilateral symmetry, 20, 302, =320=, 321.
Binomial nomenclature, 28.
=Bipinnaria=, 201.
Biramous, =243=, 257.
=Bittium=, 326, =374=.
=B. nigrum=, 326.
Bivalves, =306=, 307, 314, 315, 409.
Mud-boring, 452.
Rock-boring, 452, 460.
Blastostyles, =120=.
Blue crab, 275.
Blue-green seaweeds, 47, 48, 49.
Body-whorl, 304, =343=.
=Bolina=, 154, =156=.
=B. alata=, 154, =156=.
=B. septentrionalis=, 154, =156=.
=B. vitrea=, 154, =156=.
=Boltenia=, 473, =476=.
=B. clavata=, 473, =476=.
=Bopyridæ=, =292=.
Boreal, 23.
Boring amphipod, 290.
Boring-sponges, 105.
=Bostrychia=, 77, =89=.
=B. rivularis=, 77, =89=.
Botanical facts about algæ, =25=.
=Botryllus=, 473, =477=.
=B. gouldii=, 473, =477=.
=Bougainvillea=, =124=.
=B. superciliaris=, 116, =124=.
Box-crab, =287=.
=Brachyura=, 241, 258, =272=.
Brain-corals, 146.
Branchiæ, 302, =319=, 329, 336, =413=.
Dermal, 208.
=Branchiolaria=, 201.
=Brissopsis=, 217, =227=.
=B. lyrifera=, 217, =227=.
"Brit," =249=.
Brittle-stars, 43, 200, =214=.
Brown bodies, 190, =193=.
=Bryopsis=, 51, =59=.
=B. plumosa=, 51, =59=.
=Bryozoa=, =191=.
Buccal mass, 302, =317=.
=Buccinidæ=, 327, =391=.
=Buccinum=, 12, 309, 313, 327, 330, =392=.
=B. undatum=, 42, 44, 314, 327, 331, =392=.
=Bucidium parasiticum=, 144.
=Bugula=, 188, 192, 193, =195=.
=B. flabellata=, 188, =196=.
=B. Murrayana=, 188, =196=.
=B. turrita=, 43, 188, =195=.
=Bulla=, 324, =351=.
=B. nebulosa=, 324, =351=.
=B. occidentalis=, 324, =351=.
=B. solitaria=, 324.
=Bullidæ=, =324=.
Butterfly-shells, =323=.
=Byssus=, =415=, 426, 432.
C
=Caberea=, 188, =195=.
=C. Ellisii=, 188, =195=.
Cake-urchins, 218, =224=.
=Calappa=, 241, =287=.
=C. flamma=, 241, =287=.
=Calappidæ=, 241, =287=.
=Calcarea=, 100, =104=, =106=.
Calcareous hydroids, =129=.
Seaweeds, =31=, 147.
Californian province, =312=.
=Callinectes=, 241, =275=.
=C. hastatus=, 12, =275=.
=C. sapidus=, 241, 274, =275=.
=Calliostoma=, 312, 325, =361=.
=C. annulatum=, 325, =361=.
=C. canaliculatum=, 325, =361=.
=C. costatum=, 325, =361=.
=C. jujubinum=, 325, =361=.
=C. occidentale=, 325, =361=.
=Callista=, 311, 410.
=C. gigantea=, =450=.
=C. maculata=, =450=.
=Callithamnion=, 15, 78, 79, =90=.
=C. americanum=, 78, =90=.
=C. Baileyi=, 78, =91=.
=C. byssoideum=, 78, =91=.
=C. floccosum=, 78, =91=.
=C. Pylaisæi=, 78, =91=.
=C. seirospermum=, 78, =91=.
=Callophyllis=, 76, =82=.
=C. laciniata=, 76, =82=.
=C. variegata=, 76, =82=.
=Calothrix=, 48, =49=.
Cameo-cutting, =381=.
Campanularians, 116, 121, =125=.
Canal, 302.
Anterior, =344=.
Posterior, =344=.
System of sponge, 103.
=Cancellaria=, 310, 327, =402=.
=C. reticulata=, 327, =402=.
=Cancellariidæ=, 327, =402=.
=Cancellus=, =266=.
=Cancer=, 241, =277=.
=C. antennarius=, 241, =280=.
=C. borealis=, 241, =277=.
=C. irroratus=, 241, =277=.
=C. magister=, 241, =278=.
=C. productus=, 241, =278=.
=Cancroidæ=, 241, =277=.
=Caprella=, 8, 242, =291=.
=C. geometrica=, 242, =291=.
=Capulidæ=, 325, =369=.
Carapace, 243, =246=.
=Carcinides=, 241, =274=.
=C. mænas=, 241, =274=.
=Carcinus mænas=, 41, =274=.
=Cardiidæ=, 407, =453=.
=Cardita=, 406, =440=.
=C. borealis=, 406, =440=.
=C. floridana=, 406, =440=.
=Carditidæ=, 406, =439=.
=Cardium=, 310, 311, 407, 410, 413, =453=.
=C. corbis=, 407, =454=.
=C. elatum=, 407, =454=.
=C. islandicum=, 407, =454=.
=C. isocardia=, 407, =454=.
=C. lævigatum=, 407, =454=.
=C. magnum=, 407, =453=.
=C. mortoni=, 407, =454=.
=C. pinnulatum=, 407, =454=.
=C. quadrigenarium=, 407, =454=.
=C. serratum=, 407, =454=.
=C. substriatum=, 407, =454=.
Caribbean province, 310.
Carinated, 302.
Cartilage, =417=.
Cartilaginous, 27.
=Cassididæ=, 326, 380.
=Cassiopeia=, 133, =140=.
=C. frondosa=, 133, =140=.
=Cassis=, 310, 326, =380=.
=C. cameo=, 326, =380=.
=C. inflata=, 326, =381=.
=C. Madagascarensis=, =381=.
=C. testiculus=, 326, =381=.
=C. tuberosa=, 326, =380=.
=Caudina=, 228, =233=.
=C. arenata=, 228, =233=.
=Caulerpa=, 51, 56, =59=.
=C. Mexicana=, 51, =60=.
=C. paspaloides=, Plate VIII.
=C. plumaris=, Plate VIII.
=C. plumosa=, 51.
=C. prolifera=, 51, =60=.
=C. Wurdemanii=, 51.
=Caulerpaceæ=, 51, =59=.
=Cellepora=, 188, =197=.
=C. pumicosa=, 188, =197=.
=C. ramulosa=, 188, =197=.
=C. scabra=, 188, =197=.
=Cellularia=, 188, =195=.
=C. ternata=, 188, =195=.
=Cellularina=, 188.
=Cenobita=, 240, =268=.
=C. diogenes=, 240, =268=.
=Cenobitidæ=, 240, =268=.
Cephalic, 243, =246=.
=Cephalopoda=, 301, 315, 320, 321, =464=.
Cephalothorax, 243, =246=, 272.
=Ceramieæ=, 78, =90=.
=Ceramium=, 27, 43, 78, =92=.
=C. diaphanum=, 78, =93=.
=C. fastigiatum=, 78, =93=.
=C. rubrum=, 78, =92=.
=C. rubrum, var. proliferum=, 78, =93=.
=C. rubrum, var. secundatum=, 78, =93=.
=C. strictum=, 78, =93=.
=C. tenuissimum=, 78, =93=.
=C. tenuissimum, var. patentissimum=, 78, =93=.
=Cerata=, 353.
=Cerebratulus=, 160, =170=.
=C. angulatus=, 160, =170=.
=Cerianthus=, 144.
=Cerithidea=, 326, =375=.
=C. sacrata=, 326, =375=.
=C. scalariformis=, 326, =375=.
=Cerithiidæ=, 326, =373=.
=Cerithium=, 326, =374=.
=C. floridanum=, 326, =374=.
=C. minimum=, 326, =374=.
=C. muscarum=, 326, =374=.
=Cerostoma=, 326, =385=, 387.
=C. foliatum=, 326, =385=.
=C. nuttallii=, 326, =385=.
=Cestida=, 154, =157=.
=Cestoda=, =160=.
=Cestum=, 154, =157=.
=C. veneris=, 154, =157=.
=Cetochilus=, 239, =249=.
=Chætæ=, =173=.
=Chætangieæ=, 76, =80=.
=Chætobranchus=, 161, =182=.
=C. sanguineus=, 161, =182=.
=Chætomorpha=, 51, =53=.
=C. ærea=, 51, =53=.
=C. linum=, 51, =54=.
=C. melagonium=, 51, =53=.
=C. picquotiana=, =54=.
=C. tortuosa=, =53=.
=Chætopoda=, 161, =171=.
=Chalinopsilla=, 100, =107=.
=C. arbuscula=, 100, =107=.
=C. oculata=, 100, =107=.
=Chamædoris=, 51, =56=.
=C. annulata=, 51, =56=.
=Champia=, 77, =85=.
=C. parvula=, 77, =85=.
=Charybdæa=, 133, =137=.
=C. marsupialis=, 133, =137=.
=Cheilostomata=, 188, 194.
Chelæ, 243, =258=.
Cheliped, 243, =258=.
=Chelura=, 242, =290=.
=C. terebrans=, 13, 242, 290.
=Chicoreus rufus=, =382=.
=Chione=, 406, =451=.
=C. fluctifraga=, 406, =451=.
=C. simillima=, 406, =451=.
=C. succincta=, 406, =451=.
=Chiridotea=, 242, =294=.
=C. cæca=, 242, =294=.
=C. entomon=, 242, =294=.
=Chiton=, 9, 309, =322=.
=C. albus=, =323=.
=C. apiculatus=, =323=.
=C. ruber=, 41, =323=.
=C. spinosus=, =322=.
=Chitonidæ=, 312, 322.
=Chlorophyceæ=, 28, 47, 51.
=Chlorostoma=, 312, 325, =362=.
=C. brunneum=, 325, =362=.
=C. funebrale=, 325, =362=.
Choanocytes, =102=.
=Choanoflagellata=, 102.
=Chondria=, 77, =90=.
=C. dasyphylla=, 77, =90=.
=C. striolata=, 77, =90=.
=C. tenuissima=, 77, =90=.
=Chondrospongiæ=, 100.
=Chondrus=, 76, =80=.
=C. crispus=, 38, 76, =80=.
=Chorda=, 63, 68, =69=.
=C. filum=, 63, =69=.
=Chordaria=, 62, =67=.
=C. flagelliformis=, 43, 44, 62, =67=.
=Chordariaceæ=, 62, =67=.
=Chordata=, 19, 472, =474=.
=Chorus=, 312, 326, =388=.
=C. belcheri=, 326, =388=.
Chromatophores, =467=.
=Chrysodomus=, 12, 309, 313, 327, =392=.
=C. decemcostatus=, 327, =392=.
=Chylocladia=, 77, =85=.
=C. articulata=, 77, =85=.
=Cidaridæ=, 217, =222=.
=Cidaris=, 217, =222=.
=C. tribuloides=, 217, =222=.
Ciliary flames, 164.
Cinereous, 302.
=Cirolana=, 242, =292=.
=C. concharum=, 242, =292=.
=Cirratulidæ=, 161, =181=.
=Cirratulus=, 161, =181=.
=C. grandis=, 161, =181=.
Cirri, =172=, 302.
=Cirripedia=, 239, =250=.
Cirripeds, 251.
=Cistenides=, 162, =183=.
=C. Gouldii=, 162, =183=.
=Cladocera=, =238=.
=Cladophora=, 26, 51, =54=.
=C. arcta=, 51, =54=.
=C. gracilis=, 51, =54=.
=C. rupestris=, 51, =54=.
=Cladostephus=, 62, =65=.
=C. verticillatus=, 62, =65=.
Clam, 321, =448=.
Giant, 447.
Hard-shell, 448, 451, 456.
Little Neck, 410, 448.
Soft-shell, 456.
Worms, 176.
Classification, =19=.
Of gasteropods, =348=.
Of mollusks, =320=.
=Clava=, =122=.
=C. leptostyla=, 116, =122=.
=Clibanarius=, 240, =267=.
=C. vittatus=, 240, =267=.
=Cliona=, 100, =106=.
=C. sulphurea=, 100, 105, =106=.
=Cloaca=, =229=.
=Clymenella=, 162, =183=.
=C. torquata=, 162, =183=.
=Clypeaster=, 217, =224=.
=C. ravenellii=, 217, =224=.
=Clypeastroidea=, 217, =224=.
=Clytia=, =126=.
=C. bicophora=, 116, =126=.
=C. poterium=, 116, =126=.
Cockles, 453.
=Codiaceæ=, 51, =59=.
=Codium=, 51, =59=.
=C. tomentosum=, 51, =59=.
=Cœlenterata=, 111, 112, =113=.
=Cœlopleurus=, 217, =222=.
=C. floridanus=, 217, =222=.
Cœnosarc, 118.
Coffee-shells, 379.
Collecting, =6=.
And preserving seaweeds, =15=.
At Bar Harbor, =40=.
=Columbella=, 326, =388=.
=C. avara=, 326, =389=.
=C. corrugata=, 326, =389=.
=C. gausapata=, 326, =389=.
=C. lunata=, 326, =389=.
=C. mercatoria=, 326, =388=.
=C. similis=, 326, =389=.
=Columbellidæ=, 326, =388=.
Columella, 302, =344=.
=Comatula=, 234, =235=.
Comb-jellies, 112, 115, =155=.
Communal life, 121.
Conceptacles, =72=.
Conchs, =377=.
Conch-shell, =376=.
Concrescent, =302=.
=Confervaceæ=, 26, 51, =53=.
=Conidæ=, 327, =401=.
=Connostomæ=, =133=.
=Conus=, 313, 327, =401=.
=C. floridanus=, 327, =402=.
=C. gloria-maris=, 401.
=C. pealei=, 327, =402=.
=Copepoda=, 239, =249=.
=Corallina=, 29, 78, =96=.
=C. officinalis=, 41, 43, 78, =96=.
=C. rubrum=, 142, 146, =147=.
Coralline Crags, =192=.
Zone, 30, =31=.
=Corallineæ=, 78, =95=.
Corallite, =146=.
Corallum, =146=.
Corals, 112.
Cordate, =302=.
Cormophytes, 25.
=Cornacuspongiæ=, 100.
=Coronula diadema=, 255.
=Corymorpha pendula=, 116.
=Coryne=, 116, =123=.
=C. mirabilis=, 116, 123.
=Cosmocephala=, 160, =170=.
=C. ochracea=, 160, =170=.
=Costæ=, =302=.
Cowry-shell, =377=.
Crabe enragé, =274=.
Crabs, 244, 247, =272=.
Blue, 275.
Box-, 287.
Fiddler-, 241, 282.
Ghost-, 282.
Green, 274.
Hermit-, 264.
Kelp-, 286.
Lady-, 276.
Mud-, 281.
Oyster-, 287.
Purple shore-, 281.
Red, 278.
Rock-, 277, 280.
Sand-, 11, 241, 276, 282.
Sheep-, 285.
Shore-, 281.
Spider-, 241, 284.
Stone-, 280.
Swimming, 241, 274.
Toad-, 285.
Walking, 241.
Yellow shore-, 281.
=Crangon=, 240, =260=.
=C. franciscorum=, 240, =261=.
=C. vulgaris=, 240, =260=.
Crawfish, 240, 259, =261=.
Creeping Polyzoa, =193=.
Crenulated, 302.
=Crepidula=, 325, =369=.
=C. aculeata=, 325, =369=.
=C. adunca=, 370.
=C. fornicata=, 325, 369.
=C. navicelloides=, =370=.
=C. plana=, 325, =369=.
=C. rugosa=, =370=.
=Cribrella=, 204, 207, =211=.
=C. sanguinolenta=, 204, =211=.
Crimson Bluffs, 33.
=Crinoidea=, 200, =234=.
Crinoids, 202, 235.
Fossil, 235.
=Crisia=, 188, =194=.
=C. eburnea=, 188, =194=.
=Crossaster=, 204, =211=.
=C. papposus=, 204, =211=.
Crucibulum, 325, =370=.
=C. spinosum=, 325, =370=.
=C. striatum=, 325, =370=.
=Crustacea=, 238, =244=, 248, 257, 262.
=Cryptochiton=, =323=.
=C. stelleri=, =323=.
Cryptogams, 25.
=Cryptolithodes=, 240, 271.
=C. sitchensis=, 240, 271.
=Cryptonemiaceæ=, 78, 94.
=Cryptozonia=, 204, =211=.
Crystalline stylet, 302, =341=.
Ctenidia, 302.
=Ctenodiscus=, 204, =208=.
=C. corniculatus=, 204, =208=.
=Ctenophora=, 112, 115, 154, =155=.
=Ctenostomata=, 189, =197=.
=Cubomedusæ=, 133, =137=.
=Cucumaria crocea=, =231=.
=C. lævigata=, =231=.
=Cumacea=, 242, =288=.
=Cutleria=, 63, =71=.
=C. multifida=, 63, =71=.
=Cutleriaceæ=, 63, =71=.
Cuttlefishes, 44, 315, =467=.
=Cuvieria squamata=, =232=.
Cuvierian organs, =231=.
=Cyanea=, 133, 136, 138.
=C. arctica=, 44, 133, 138, =144=.
=C. fulva=, 133, =139=.
=C. versicolor=, 133, =139=.
=Cyanophyceæ=, 28, 48, =49=.
=Cyclomyaria=, 472.
=Cyclops=, 239, =249=, 250.
=Cyclostomata=, 188, =193=.
=Cydippida=, 154, 156.
=Cymopolia=, 51, =57=.
=C. barbata=, 51, =57=.
=Cynthia=, 473, =476=.
=C. carnea=, 473, =476=.
=C. partita=, 473, =476=.
=C. pyriformis=, 473, =476=.
=Cypræa=, 326, 334, =377=.
=C. aurantia=, =377=.
=C. exanthema=, 326, =378=.
=C. moneta=, =378=.
=C. spadacea=, 326, =379=.
=C. spurca=, 326, =378=.
=Cypræidæ=, 326, 377.
=Cypridina=, =238=.
=C. islandica=, =441=.
=Cyprinidæ=, 406, =441=.
=Cypris=, =238=.
=Cyrena=, 311.
=Cystoclonium=, 77, =83=.
=C. cirrhosa=, 77, =83=.
=C. purpurascens=, 77, =83=.
=Cystoseira=, 63, =73=.
=C. expansa=, 63, =73=.
=Cytherea=, 406, =450=.
=C. gigantea=, 406, =450=.
=C. maculata=, 406, =450=.
D
Dactylopores, =129=.
Dactylozoöids, =129=.
=Daphnia=, =238=.
=Dasya=, 77, 79, =89=.
=D. elegans=, 77, =89=.
=D. plumosa=, 77, =89=.
=Dasycladaceæ=, 51, =57=.
=Dasycladus=, 51, =57=.
=D. occidentalis=, 51, =57=.
=Decapoda=, 240, 257, 301, =468=.
Decussated, =303=.
=Delesseria=, 77, 79, 86.
=D. alata=, 77, 86.
=D. Leprieurii=, 77, 86.
=D. sinuosa=, 77, 86.
=Delesserieæ=, 77, =85=.
=Dendronotidæ=, 324.
=Dendronotus=, 41, 42, 324, =353=.
=D. arborescens=, 324, =353=.
=Dentalidæ=, 327, =402=.
=Dentalium=, 268, 327, 328, 404.
=D. dentale=, 327, 403.
=D. hexagonum=, 327, =403=.
=D. pretiosum=, 327, =403=.
Dermal branchiæ, =208=.
=Desmacidonidæ=, 100.
=Desmarestia=, 15, 62, 66.
=D. aculeata=, 43, 62, 66.
=D. ligulata=, 62, 67.
=D. viridis=, 62, 66.
=Desmarestiaceæ=, 62, 66.
Desmids, =33=.
=Desmosticha=, 217, 221.
Devil's pocket-books, 12.
Dextral, 303, =345=.
=Diadema=, 217, =222=.
=D. setosum=, 217, =222=.
=Diadematidæ=, 217, =222=.
=Diastopora=, 188, =194=.
=D. patina=, 188, =194=.
=Diastylis=, 242, =288=.
=D. quadrispinosus=, 242, =288=.
=Diatocardia=, 300, 324, =356=.
=Diatomaceæ=, 38.
Diatomaceous ooze, =21=.
Diatoms, 21, =32=.
Green, 435.
=Dibranchiata=, 301, 464, =468=.
=Dictyosiphon=, 62, =67=.
=D. fœniculaceus=, 62, =67=.
=Dictyosiphonaceæ=, 62, =67=.
=Dictyota=, 63, =70=.
=D. dichotoma=, 63, =70=.
=D. fasciola=, 63, =70=.
=Dictyotaceæ=, 63, =70=.
=Diopatra=, 10, 161, =178=.
=D. cuprea=, 161, =178=.
=Diploria=, 141, 148.
=D. cerebriformis=, 141, =148=.
=Discomedusæ=, 133, =137=.
Distribution of algæ, =30=.
Of animal life in the sea, =23=.
=Doliidæ=, 326, =379=.
=Doliolum=, 472.
=Dolium=, 310, 326, =379=.
=D. galea=, 326, =379=.
=D. perdix=, 326, =379=.
=Donacidæ=, 406, =445=.
=Donax=, 10, 406, =445=.
=D. californicus=, 406, =445=.
=D. variabilis=, 406, =445=.
=Dorididæ=, 324.
=Doris=, 309, 324, =354=.
=D. bilamellata=, 324, =354=.
=Dorocidaris=, 217, =222=.
=D. Blakei=, 217, =222=.
=D. papillota=, 217, =222=.
Dorsal surface, 201, 202.
=Dosinia=, 406, =450=.
=D. discus=, 406, =450=.
=D. elegans=, 406, =450=.
Drill, =383=.
=Dromia=, =105=.
=Dromidæ=, 240, =264=.
Dulse, =38=.
=Dumontieæ=, 78, =94=.
E
Ears, =247=, 435.
Of corn, 12.
=Echidnocerus=, 240, =270=.
=E. cibarius=, 240, =270=.
=E. foriminatus=, 240, =271=.
=Echinanthidæ=, 217, =224=.
=Echinanthus=, 217, =225=.
=E. rosaceus=, 217, =225=.
=Echinarachnius=, 217, =225=.
=E. excentricus=, 217, =225=.
=E. parma=, 44, 217, =225=.
=Echinaster=, 204, =211=.
=E. sentus=, 204, =211=.
=Echinasteridæ=, 204, =211=.
=Echinidæ=, 217, =223=.
=Echinodermata=, 200, 202, 305.
=Echinoidea=, 200, 203, 217, =218=, 221.
=Echinometra=, 217, =223=.
=E. subangularis=, 217, =223=.
=Echinometridæ=, 217, =223=.
=Echinus=, 217, =224=.
=E. gracilis=, 217, =224=.
=Ectocarpaceæ=, 28, 62, =64=.
=Ectocarpus=, 28, 29, 62, =64=.
=E. Hooperi=, 29.
=E. littoralis=, 62, 64.
=E. siliculosus=, 62, =65=.
=E. tomentosus=, 62, =65=.
=E. viridis=, 62, =65=.
Ectoderm, =101=, 118.
=Ectoprocta=, 188, =193=.
=Edwardsia=, =144=.
Eel-grass, 12.
Egg-capsules, =314=.
Egg-cases, =11=, 12, 367.
Eggs, 248, 314, 343, 414.
=Elachista=, 62, =67=.
=Elachistaceæ=, =67=.
=Elytra=, =173=.
Embryology, =20=.
=Encœliaceæ=, 62, =65=.
=Encope=, 217, =226=.
=E. michelini=, 217, =226=.
Endoderm, =101=, 118.
Endopodite, 243, =246=.
Ensis, 310, 407, =458=.
=E. americanus=, =458=.
=E. directus=, 407, =458=.
=Entalis=, 327.
=E. striolata=, 327, =403=.
=Enteromorpha=, 26, 30, 51, =55=.
=E. clathrata=, 51, =55=.
=E. compressa=, 51, =55=.
=E. intestinalis=, 51, =55=.
=E. lanceolata=, 51, =56=.
=Entomostraca=, 238, =249=.
=Entoprocta=, 189, =198=.
Ephyrula, =136=.
=Epialtus=, 241, =286=.
=E. productus=, 241, =286=.
Epidermis, 303, =345=, 347.
Epimera, 243.
Epipodite, 243.
Epistoma, 243.
=Epizoanthus americanus=, =267=.
Equilateral, 418.
Equivalve, 418.
Erect Polyzoa, =193=.
=Errantia=, 161, =173=, 180.
=Escharella=, 188, =197=.
=E. variabilis=, 188, =197=.
=Escharina=, 188.
Escutcheon, 418.
=Esperiopsis=, 100.
=E. quatsinoensis=, =100=.
=Eucheuma=, 77, =84=.
=E. isiforme=, 77, =84=.
=Eucope=, =125=.
=E. diaphana=, 116, =125=.
=Eucratea=, 188, =195=.
=E. chelata=, 188, =195=.
=Eudendrium ramosum=, =116=, Plate XLI.
=Eugorgia aurantica=, Plate XLVI.
=Eulamellibranchiata=, 301, 406, 420, =438=.
=Eunicea lugubris=, Plate XLVII.
=Eunicidæ=, 161, =178=.
=Eupagurus kroyeri=, =267=.
=E. prideaux=, =267=.
=E. pubescens=, =267=.
=Eupanopeus=, 241.
=E. herbstii=, 241, =281=.
=Euphausia=, =239=, 247.
=Euphyllopoda=, =238=.
=Eupleura=, 326, =384=.
=E. caudata=, 326, =384=.
=Euryalida=, 213, =215=.
=Eurypanopeus=, 241.
=E. depressus=, 241, =281=.
=Euspongia=, 100, =107=.
=E. officinalis=, 100, =107=.
=E. officinalis=, var. =adriatica=, 100, =108=.
=E. officinalis=, var. =dura=, 100, =108=.
=E. officinalis=, var. =mollissima=, 100, =108=.
=E. officinalis=, var. =rotunda=, 100, =108=.
=Eusponginæ=, =100=.
=Euthora=, 77, =83=.
=E. cristata=, 77, =83=.
Exopodite, 243, 246.
Exoskeleton, 201, 203, =205=.
Ex-umbrella, =120=.
Eyes, 247, 322, =333=, 415, 416.
F
Family, 20.
=Fasciolaria=, 311, 327, 331, =397=.
=F. distans=, 327, =397=.
=F. gigantea=, 327, =397=.
=F. tulipa=, 327, =397=.
=Fasciolariidæ=, 327.
Feather-stars, 200, =234=.
=Fenja=, =144=.
Fiddler-crabs, 12, 241, =282=.
Filamentous plants, =26=.
=Filibranchiata=, 301, 405, 420, =423=.
Finger-pores, =129=.
=Fissurella=, 324, =357=.
=F. alternata=, 324, =357=.
=F. aspersa=, =324=.
=F. barbadensis=, 324, =357=.
=Fissurellidæ=, 324, =357=.
Flagellate Infusoria, =102=.
Flatworms, =164=.
=Florideæ=, 28, =31=, 76.
=Flustra=, 188, =196=.
=F. foliacea=, =192=.
=F. membranacea=, 188, =196=.
=Flustrina=, 188.
Foot, 303, 317, 320, 321, 328, =415=.
Gasteropod, =334=.
=Foraminifera=, =21=, 22.
Fossette, 303, 418.
=Fovia=, 160, =167=.
=F. Warrenii=, 160, =167=.
Free-swimming colonies, =130=.
Frond, =26=.
=Fucaceæ=, 27, 63, =71=.
=Fucus=, 15, 17, 30, 63, 64, =72=.
=F. ceranoides=, 63, =73=.
=F. furcatus=, 63, =73=.
=F. serratus=, 63, =73=.
=F. vesiculosus=, 38, 63, =72=.
=Fulgur=, 10, 11, 310, 314, 327, 330, =394=.
=F. canaliculata=, 12, 327, =395=.
=F. carica=, 12, 327, =395=.
=F. perversa=, 327, =396=.
=F. pyrum=, 327, =396=.
Functional siphon, 331.
Fuscous, 303.
Fusiform, =303=.
G
=Gammarus=, 9, 43, 242, =290=.
=G. annulatus=, =290=.
=G. locusta=, 242, =290=.
=G. mucronatus=, =290=.
=Gasteropoda=, 300, 320, 324, =328=, 335.
Gastric mill, 243, =247=.
Gastropores, 129.
=Gelasimus minax=, =282=.
=G. pugilator=, =282=.
=G. pugnax=, =282=.
Gelatinous, =27=.
=Gelidieæ=, 76, =80=.
=Gelidium=, 76, =80=.
=G. corneum=, 76, =80=.
=G. Coulteri=, Plate XVII.
Generic name, =28=.
Genus, 20.
Geographical distribution, =308=.
=Gephyrea=, 171, 185.
=Geryonopsidæ=, 116, =128=.
Ghost-crab, =282=.
Giant crab of Japan, =244=.
=Gigartina=, 28, 76, =81=.
=G. mamillosa=, 76, =81=.
=G. microphylla=, 76, =81=.
=G. radula=, 76, =81=.
=G. spinosa=, 76, =81=.
=Gigartinaceæ=, 28, 76, =80=.
Gills, =247=, 329, =336=, =413=.
Girdle, 322.
Glass-rope sponge, =102=.
=Globigerina=, =21=.
Globigerina ooze, =21=.
=Gloiosiphonia=, 78, =94=.
=G. capillaris=, 78, =94=.
=Gloiosiphonieæ=, 78, =94=.
Glove sponge, =104=.
=Glycera=, 161, =180=.
=G. americana=, 161, =180=.
=G. dibranchiata=, 161, =180=.
=Glyceridæ=, 161, =179=.
=Glycimeridæ=, 407, =459=.
=Glycimeris=, 407, =459=.
=G. generosa=, 407, =459=.
=Glyphis=, 324, =358=.
=G. aspersa=, 324, =358=.
Gonads, 135, =341=.
Gonangium, =118=.
Gonophore, 118.
Goose-barnacle, =252=.
=Gorgonacea=, 141, =152=.
=Gorgonia anceps=, Plate XLVI.
=G. flabellum=, Plate XLVII.
=Gracilaria=, 77, =84=.
=G. lichenoides=, 39.
=G. multipartita=, 77, =84=.
=G. spinosa=, 39.
=Grantia=, 100, =106=.
=G. ciliata=, 100, 105, =106=.
=Grapsidæ=, 241, =281=.
Grass sponge, =104=.
=Grateloupia=, 78, =94=.
=G. Cutleria=, 78, =94=.
=Grateloupieæ=, 78, =94=.
Green glands, =246=.
=Griffithsia=, 15, 29, 78, =91=.
=G. Bornetiana=, 78, =91=.
=G. corallina=, 29.
=Grinnellia=, 29, 77, =86=.
=G. Americana=, 29, 77, =86=.
=Gymnogongrus=, 76, =82=.
=G. Norvegicus=, 76, 82.
=Gymnolæmata=, 188, =193=.
H
=Halcyonoida=, 141, =150=.
Halcyonoids, =142=.
=Halichondria=, 100, =107=.
=H. panicea=, 100, =107=.
=Halidrys=, 63, =73=.
=H. osmunda=, 63, =73=.
=Halimeda=, 51, =58=.
=H. opuntia=, 51, =59=.
=H. tridens=, 51, =59=.
=H. tuna=, 51, =58=.
=Haliotidæ=, 324, =358=.
=Haliotis=, 9, 312, 324, =358=.
=H. cracherodii=, 324, =359=.
=H. rufescens=, 324, =359=.
=H. splendens=, 324, =359=.
=Haliseris=, 63, =71=.
=H. polypodioides=, 63, =71=.
=Halosaccion=, 78, =95=.
=H. ramentaceum=, 78, =95=.
=Halymenia=, 78, =94=.
=H. ligulata=, 78, =94=.
=Haminea solitaria=, 324, =351=.
=Harmothoë=, 161, =174=.
=H. imbricata=, 161, =174=.
Heart, 416.
Heart and vascular system, =341=.
Heart-urchins, 218, =226=.
=Heliaster=, 204, 205, =212=.
=H. multiradiata=, 204, =212=.
=Heliasteridæ=, 204, =212=.
=Helipora=, 147.
Helmet-shells, =380=.
=Helminthocladieæ=, 76, =79=.
=Hemigrapsus=, 241, =281=.
=H. nudus=, 241, =281=.
=H. oregonensis=, 241, =281=.
=Hemimyaria=, 472.
Herbarium, 17.
Hermit-crabs, 12, 258, 259, =264=, 362.
=Heterocœla=, 100.
=Heterograpsus nudus=, =281=.
=H. oregonensis=, =281=.
=Heterorrhaphidæ=, 100.
=Hildenbrandtia=, 78, =95=.
=H. rosea=, 40, 78, =95=.
=Himanthalia=, 63, =71=.
=H. lorea=, 63, =71=.
=Hippa=, 10, 240, =268=.
=H. analoga=, 240, =269=.
=H. talpoida=, 10, 11, 240, =268=.
=Hippasteria=, 204, =209=.
=H. phrygiana=, 204, =209=.
=Hippidæ=, 240, =268=.
=Hippoconcha=, 240, =264=.
=H. arcuata=, 240, =264=.
=Hippospongia=, 100, =108=.
=H. canaliculata=, 100, =108=.
=H. canaliculata=, var. =flabellum= 100, =109=.
=H. canaliculata=, var. =gossypina=, 100, =108=.
=H. equina=, 100, =108=.
=H. equina=, var. =agaricina=, =108=.
=H. equina=, var. =cerebriformis=, 100, =108=.
=H. equina=, var. =dura=, =108=.
=H. equina=, var. =elastica=, 100, =108=.
=H. equina=, var. =meandriformis=, 100, =108=.
=Hircinia=, 100, =109=.
=H. campana=, 100, =109=.
Histology, =20=.
Holdfasts, 26.
=Holocampa=, 141, =145=.
=H. producta=, 141, =145=.
=Holothuria edulis=, =232=.
Holothurians, 202, 203.
=Holothuroidea=, 200, 228, =229=.
=Homarus=, 240, =261=.
=H. americanus=, 240, =262=.
=H. capensis=, =261=.
=H. vulgaris=, =261=.
=Homorrhaphidæ=, 100.
How to arrange a herbarium, =17=.
=Hyas=, 241, 284, =285=.
=H. araneus=, 241, =285=.
=H. coarctatus=, 241, =285=.
=H. lyratus=, 241, =285=.
=Hybocodon=, =124=.
=H. prolifer=, 116, =124=.
=Hydractinia=, 116, =122=.
=H. polyclina=, 116, =122=, 266.
=Hydrallmania falcata=, =127=.
Hydranth, 118, 119.
=Hydrocorallina=, 117, =129=.
Hydroids, 22, 114, =119=.
Hydrorhiza, 118.
Hydrosoma, 118.
Hydrotheca, 118.
=Hydrozoa=, 112, 114, 116, =119=, 120.
=Hypnea=, 77, =84=.
=H. musciformis=, 77, =84=.
I
Ideal mollusk, =317=.
=Idotea=, 242, =293=.
=I. irrorata=, =293=.
=I. marina=, 242, =293=.
=I. metallica=, 242, =294=.
=I. ochotensis=, 242, =294=.
=I. wosnesenskii=, 242, =294=.
=Idyia=, 154, =157=.
=I. cyanthina=, 154, =158=.
=I. roseola=, 154, =157=.
=Inarticulata=, 188.
=Infusoria=, 21, 101.
Interambulacral areas, 201, 202, 218.
Introvert, 186.
=Iridæa=, 76, =82=.
=Isopoda=, 242, =291=.
Isopods, 12.
J
=Janthina=, 325, =364=.
=J. fragilis=, 325, =365=.
=Janthinidæ=, 325, =364=.
=Jellyfishes=, 7, 44, 112, 115, 119, =134=.
Jonah crab, =277=.
K
Kelp, =38=.
Kingdom, =19=.
Kitchen-middens, 432.
L
Labial palps, 416.
=Labiosa canaliculata=, =447=.
=Lacuna=, 309, 326, =373=.
=L. vincta=, 12, 44, 326, =373=.
Lady-crab, =276=.
=Lambrus=, 241, =286=.
=L. pourtalesii=, 241, =286=.
=Lamellibranchiata=, 409.
Lamelliform, 303.
=Laminaria=, 43, 63, =70=.
=L. digitata=, 44, 63, =70=.
=L. longicruris=, 63, =70=.
=L. saccharina=, 63, =70=.
=Laminariaceæ=, 31, =35=, 38, 63, 64, 68.
Laminarian zone, 30,=31=.
Larva, 201.
=Larvacea=, 472.
=Laurencia=, 77, =89=.
=L. pinnatifida=, 77, =89=.
Laver, =38=.
=Leathesia=, 62, =68=.
=L. difformis=, 41, =68=.
=L. tuberiformis=, =68=.
=Leda=, 309, 405, =422=.
=L. tenuisulcata=, 405, =422=.
=Lepas=, 239, 250, =252=.
=L. anatifera=, 239, =253=.
=L. pectinata=, 239, =253=.
=L. striata=, 239, =253=.
=Leptodora=, =238=.
=Leptogorgia Agassizii=, Plate XLVII.
=L. rigida=, Plate XLVII.
=Leptoliniæ=, 116, =121=.
=Leptomedusæ=, =116=.
=Leptoplana=, 160, =166=.
=L. folium=, 160, =166=.
=Lessonia=, =36=, 63.
=Leucosolenia=, 100, =106=.
=L. botryoides=, 100, =106=.
=Liagora=, 76.
=Libinia=, 241, =284=.
=L. dubia=, 241, =284=.
=L. emarginata=, 241, =284=.
Ligament, 417.
=Limnoria=, 242, =292=.
=L. lignorum=, 13, 242, 290, =292=.
Limpets, 9.
=Limulus=, 242, =294=.
=L. moluccanus=, =295=.
=L. polyphemus=, 242, =294=.
=Linerges=, 133, =139=.
=L. mercurius=, 133, =139=.
Lines of growth, =344=, 347.
=Lineus marinus=, =167=.
=L. sanguineus=, =168=.
Lingual ribbon, 303, =340=.
Lip, inner, =344=.
Outer, =344=.
Lithocysts, =135=.
=Lithodes=, 240, =270=.
=L. maia=, 240, =270=.
=Lithodidæ=, 240, =270=.
Littoral, =23=.
Species, 308.
Zone, =30=.
=Littorina=, 9, 309, 311, 325, 338, =370=.
=L. angulifera=, 325, =372=.
=L. irrorata=, 325, =372=.
=L. litorea=, 8, 41, 42, 325, =371=.
=L. palliata=, 42, 325, =372=.
=L. planaxis=, 325, =373=.
=L. rudis=, 41, 42, 325, =371=.
=L. scutulata=, 325, =373=.
=Littorinella minuta=, 12.
=Littorinidæ=, 325, 338, =370=.
=Livona=, 325, 362.
=L. pica=, 268, 325, =362=.
=Lizzia=, 120.
=Lobata=, 154, =156=.
Lobsters, 240, 247, 250, 258, 259, =261=.
=Loligo=, 464, 467, 469.
=L. brevis=, 464, =469=.
=L. Pealei=, 464, =469=.
=Lomentaria=, 77, =85=.
=L. Baileyana=, 77, =85=.
Lophophore, 190, =193=.
=Lophothuria=, 228.
=L. fabricii=, 228, =232=.
=Loripes=, 406, =443=.
=L. edentula=, 406, =443=.
=Lottia=, 324, =357=.
=L. gigantea=, 324, =357=.
=Lovenia=, 217, =227=.
=L. cordiformis=, 217, =227=.
=Loxorhynchus=, 241, =285=.
=L. crispatus=, 241, =285=.
=Lucapina=, 324, =358=.
=L. crenulata=, 324, =358=.
=Lucernaria=, 133, =136=.
=L. auricula=, 133, =136=.
=Lucina=, 311, 406, =442=.
=L. californica=, 406, =443=.
=L. dentata=, 406, =443=.
=L. floridana=, 406, =442=.
=L. nuttallii=, 406, =443=.
=L. pennsylvanica=, 406, =442=.
=L. tigrina=, 406, =442=.
=Lucinidæ=, 406, =442=.
=Luidia=, 204, =209=.
=L. alternata=, 204, =209=.
=L. clathrata=, 204, =209=.
=L. senegalensis=, 204, =209=.
=Lumbriconereis=, 161, =179=.
=L. tenuis=, 161, =179=.
=Lunatia=, 12, 309, 314, 325, =367=.
=L. heros=, 10, 12, 44, 325, =367=.
=L. lewisii=, 325, =368=.
=L. triseriata=, 325, =367=.
Lunules, =224=, 303, 418.
=Lyngbya=, 48.
=L. æstuarii=, =50=.
=L. ferruginea=, =50=.
=L. majuscula=, =50=.
M
=Macoma=, 406, =444=.
=M. baltica=, 406, =445=.
=M. nasuta=, 406, =444=.
=M. proxima=, 406, =445=.
=M. secta=, 406, =444=.
=M. tenta=, 406, =445=.
=Macrocystis=, =35=, 63.
=M. pyrifera=, 36, =70=.
=Macrura=, 240, 258, =259=, 272.
=Mactra=, 310, 406, 410, =446=.
=M. lateralis=, 406, =447=.
=M. ovalis=, 406, =447=.
=M. similis=, 406, =447=.
=M. solidissima=, 406, =446=.
=Mactridæ=, 406, =446=.
Madreporic plate, 201, =203=, =206=, 218.
=Maiidæ=, 241, =284=.
=Malacostraca=, 239, =257=.
Mandibles, =246=, 258.
Mantle, 303, =316=, 319, 328, 331, =410=.
Mantle cavity, 303, 319, =336=.
Mantle fusion, =412=.
=Margarita=, 309, 325, =360=.
=M. cinerea=, 325, =360=.
=M. helicina=, 12, 44, 325, =360=.
=M. undulata=, 325, =360=.
Margin, 417.
Anterior, 417.
Dorsal, 417.
Posterior, 417.
Ventral, 417.
=Marginella=, 311, 327, =399=.
=M. apicina=, 327, =399=.
=Marginellidæ=, 327, =399=.
Marine invertebrates, 97.
Maxillæ, 243, =246=, 258.
Maxillipeds, 243, =246=, 258.
=Meckelia=, 160, =169=.
=M. ingens=, 160, =169=.
=M. rosea=, 160, =169=.
=Mediaster=, 204, =209=.
=M. æqualis=, 204, =209=.
=Megalops=, =248=, 273.
=Meleagrina margaritifera=, 313, 430, 431.
=Melita nitida=, =290=.
=Mellita=, 217, =225=.
=M. testudinata=, 217, =225=.
=Melobesia=, 78, =96=.
=Melongena=, 311, 327, =396=.
=M. corona=, 327, =396=.
Membranaceous, 27.
=Membranipora=, 188, 192, =196=.
=M. lineata=, 188, =196=.
=M. pilosa=, 43, 188, =196=.
=M. tenuis=, 188, =197=.
=Menippe=, 241, =280=.
=M. mercenaria=, 241, =280=.
=Meristomes=, 242, =294=.
Mesoderm, =101=, 118.
=Mesoglœa=, 62, =68=.
=M. divaricata=, 62, =68=.
=M. virescens=, 62, =68=.
=Metalia=, 217, =227=.
=M. pectoralis=, 217, =227=.
Metameres, =243=.
Metapodium, 376.
=Metazoa=, 101.
=Metridium marginatum=, 42.
=Microciona=, 100, =107=.
=M. prolifera=, 100, =107=.
=Microcladia=, 78, =93=.
=M. borealis=, 78, =93=.
=M. Coulteri=, 78, =93=.
=Millepora=, =129=.
=M. alcicornis=, 117, =129=.
=Mitra=, 313.
=Mnemiopsis=, 154, =157=.
=M. Leidyii=, 154, =157=.
=Modiola=, 309, 405, =426=.
=M. modiolus=, 405, =428=.
=M. nigra=, =429=.
=M. plicatula=, 405, =429=.
=M. recta=, 405, =429=.
=M. tulipa=, 405, =429=.
=Mœra levis=, =290=.
=Moina=, =238=.
=Moira=, 217, =226=.
=M. atropos=, 217, =226=.
=Molgula=, 473, =475=.
=M. arenata=, 473, =476=.
=M. manhattensis=, 473, =475=.
=M. pellucida=, 473, =476=.
=Mollia=, 188, =197=.
=M. hyalina=, 188, =197=.
=Mollusca=, 300, =305=, 328.
=Monoceras=, 312, 326, =387=.
=M. engonatum=, 326, =388=.
=M. lapilloides=, 326, =388=.
Monomyarian, =303=, 430.
=Monostroma=, 26, 51, =55=.
=Monotocardia=, 300, 325, =364=.
Morphology, 20.
Moss-animals, =191=.
Mother-of-pearl, 431.
Moulting, =248=, 259, 263.
Mounting seaweeds, =16=.
Mouth, 329, =333=.
Mud-crabs, 12.
Muddy shores, =12=.
Multivalve, 307.
=Murex=, 326, 331, =382=.
=M. fulvescens=, =383=.
=M. pomum=, 326, =383=.
=M. rufus=, 326, =382=.
=M. tenuispina=, =343=, 347.
=Muricea specifera=, Plate XLVI.
=Muricidæ=, 326, =381=.
=Muricinæ=, 326, =381=, 385.
Muscles, =248=.
Musical sands, 2.
Mussel, great horse-, 428.
Mussels, 43, 321, =426=.
=Mya=, 309, 407, =456=.
=M. arenaria=, 3, 42, 44, 311, 407, =456=.
=Mycedium fragile=, Plate XLV.
=Myidæ=, 407, =456=.
=Myrionema=, 62, 68.
=Mysis=, 239, =257=.
=M. sternolepsis=, 239, =257=.
=Mytilidæ=, 406, =426=.
=Mytilus=, 41, 309, 406, =426=.
=M. californicus=, 405, =428=.
=M. edulis=, 42, 43, =287=, 405, 427, =428=.
=M. hamatus=, 405, =428=.
N
Naming of plants, =28=.
=Nanomia=, =130=.
=N. cara=, 117, =130=.
=Narcomedusæ=, 117.
=Nassa=, 3, 10, 12, 327, 335, =390=.
=N. fossata=, 327, =391=.
=N. mendica=, 327, =391=.
=N. obsoleta=, 10, 12, 327, =390=.
=N. perpinguis=, 327, =391=.
=N. tegula=, 327, =391=.
=N. trivittata=, 10, 11, 327, =390=.
=N. vibex=, 327, =391=.
=Nassidæ=, 327, =390=.
=Natica=, 311, 325, 334, =367=.
=N. canrena=, 325, =368=.
=N. clausa=, 325, =368=.
=N. heros=, =367=.
=Naticidæ=, 325, =366=.
=Nauplius=, =248=, 251.
=Nautilus=, 328, =467=.
=Navicula ostrearia=, 435.
Nekton, =23=.
=Nemalion=, 76, =79=.
/N. multifidum/, 76, =79=.
/Nemalionaceæ/, 76, =79=.
=Nemathelminthes=, 159, 161, =170=.
=Nematoda=, 161, =170=.
Nematophore, 118.
Nemerteans, =167=.
=Nemertes=, 160, =169=.
=N. socialis=, 160, =169=.
=N. viridis=, 160, =169=.
=Nemertinea=, 160, =167=.
=Neopanopeus=, 241.
=N. texana=, 241, =281=.
Nephridia, =319=.
Nephridium, 303.
=Nephthydidæ=, 161, =177=.
=Nephthys=, 161, =178=.
=N. ingens=, 161, =178=.
=N. picta=, 161, =178=.
=Nereidæ=, 161, =176=.
=Nereis=, 161, =176=.
=N. limbata=, 161, =177=.
=N. pelagica=, 161, =177=.
=N. virens=, 161, =177=.
Nereocystis, 63, 70.
=N. Lütkeana=, =35=.
=Nerine=, 161, =181=.
=N. agilis=, 161, =181=.
=N. coniocephala=, 161, =181=.
=Nerita=, 325, =363=.
=N. peleronta=, 325, =363=.
=N. tessellata=, 325, =363=.
=N. versicolor=, 325.
=Neritidæ=, 325, =363=.
=Neritina=, 311, 325, =363=.
=N. reclivata=, 325, =364=.
=N. viridis=, 325, =364=.
Nervous system, =247=, =320=.
=Neverita=, 309, 325, =368=.
=N. duplicata=, 11, 325, =367=.
=N. recluziana=, 325, =368=.
=Nicothoë=, 239, =250=.
=Nidorella=, 204, =210=.
=N. armata=, 204, =210=.
=Nitophyllum=, 77, =85=.
=N. laceratum=, 77, =85=.
=N. punctatum=, 77, =86=.
=N. Ruprechteanum=, 77, =86=.
Noah's-ark shell, 426.
Node, 303.
Nodules, 344.
=Non-Calcarea=, 100, =104=, 106.
=Norrisia=, 312.
=Nostocaceæ=, 48.
=Nucula=, 309, 405, =422=.
=N. proxima=, 405, =422=.
=Nuculidæ=, 405, =421=.
Nudibranch, 328, 349, 353.
=Nudibranchiata=, 300, 324, =352=.
Nullipores, =31=, 147.
Nummulites, 22.
O
=Obelia=, =125=.
=O. commissuralis=, 116, =125=.
=Oceania=, =125=.
=O. languida=, 116, =125=.
=Ocinebra=, 326, =384=.
=O. circumtexta=, =385=.
=O. interfossa=, 326, =385=.
=O. lurida=, 326, =384=.
=O. poulsoni=, 326, =384=.
Octopi, 315.
=Octopoda=, 301, =464=, 468.
Octopus, 464, 468.
=Oculina=, 141, =148=.
=Ocypoda=, 11, 241, =282=.
=O. arenaria=, 241, 274, =282=.
=Ocypodidæ=, 241, =282=.
Odontophore, =303=.
=Oliva=, 10, 311, 313, 327, 334, =400=.
=O. literata=, 327, =400=.
=Olivella=, 10, 312, 327, =400=.
=O. biplicata=, 327, =400=.
=O. boetica=, 327, =401=.
=O. mutica=, 327, =400=.
=Olividæ=, 327, =400=.
=Ommastrephes=, 464, 468, =469=.
=O. illecebrosus=, 464, =469=.
Opercula, 193.
Operculum, 254, 303, =331=, 355.
=Ophiocoma=, 213, =216=.
=O. æthiops=, 213, =216=.
=O. Alexandri=, 213, =216=.
=O. riisei=, 213, =216=.
=Ophiopholis=, 213, =215=.
=O. aculeata=, 43, 213, =215=.
=Ophiothrix=, 213, =216=.
=O. angulata=, 213, =216=.
=Ophiurida=, 213, =215=.
=Ophiuroidea=, 200, 213, =214=.
=Opisthobranchiata=, 300, 324, 349, =350=.
Oral, 202.
Surface, 201.
Orbits, =243=.
=Orchestia=, 11, 43, 242, =289=.
=O. agilis=, 242, =289=.
Organ-pipe coral, =151=.
Organs of feeling, =249=.
Orifice, 190, 412.
=Oscillaria=, 48, =49=.
Osphradium, 303, =339=.
Ossicles, 201, =203=, 218.
=Ostracoda=, =238=.
=Ostrea=, 405, 410, =435=.
=O. edulis=, 435.
=O. frons=, 405, =435=.
=O. lurida=, 405, =435=.
=O. virginica=, 310, 405, =435=.
=Ostreidæ=, 405, =432=.
Otocysts, =165=, =303=.
Otter Cliffs, =43=.
=Ovalipes=, 241, =276=.
=O. ocellatus=, 241, =276=.
Ovicell, 190, =193=.
Oyster-crab, =287=.
Oyster-culture, 432.
Oysters, 321, 432.
Pearl-, 430, 431, 432.
P
Pacific faunal divisions =311=.
=Pacygrapsus=, 241, =282=.
=P. crassipes=, 241, =282=.
=Padina=, 63, =71=.
=P. pavonia=, 63, =71=.
=Paguridæ=, 240, =264=.
=Pagurus=, 240, =267=.
=P. bernhardus=, 240, =267=.
=P. longicarpus=, 240, =267=.
=P. pollicaris=, 240, =267=.
=Palæmonetes=, 240, =260=.
=P. vulgaris=, 240, =260=.
=Palæmon vulgaris=, =260=.
Pallial line, 303, 418.
Sinus, 303, 419.
Palps, =176=, 416.
Palpus, =258=.
Panamic province, =312=.
=Pandora=, 407, =463=.
=P. trilineata=, 407, =463=.
=Pandoridæ=, 407, =463=.
=Panopeus=, 12, =281=.
=Pantopoda=, 242, =296=.
=Panulirus=, 240. =263=.
=P. americanus=, =263=.
=P. argus=, 240, =263=.
=P. interruptus=, 240, =263=.
Papillaceous, 303.
Paraphyses, =72=.
Parapodia, =171=.
Parenchyma, 26.
=Parypha=, =123=.
=P. crocea=, 116, =123=.
=Peachia=, =144=.
Pearls, 430, 431.
=Pecten=, 309, 405, =435=.
=P. æquisulcatus=, 405, =438=.
=P. dislocatus=, 405, =437=.
=P. hastatus=, 405, =438=.
=P. irradians=, 405 =437=.
=P. islandicus=, 405, =436=.
=P. jacobius=, =436=.
=P. magellanicus=, 287, 405, =436=.
=P. tenuiscostatus=, 436.
=Pectinidæ=, 405, =435=.
Pedal opening, 412.
=Pedata=, 228, =231=.
=Pedicellariæ=, 201, =205=, =219=.
=Pedicellina=, 189, =198=.
=P. americana=, 189, =198=.
=Pelagia=, 133, =139=.
=P. cyanella=, 133, =139=.
Pelagic, =23=.
Flora, 38.
=Pelecypoda=, 301, 320, 321, 405, =409=, 420.
Classification of, =419=.
=Peltogaster=, 239, =256=.
Pen, 467.
=Penæus=, 240, =260=.
=P. brasiliensis=, 240, =260=.
=P. setiferus=, 240, =260=.
=Penicillus=, 51, =58=.
=P. capitatus=, 51, =58=.
=P. dumentosus=, 51, =58=.
=P. Phœnix=, 51, =58=.
=Pennaria=, =124=.
=P. gibbosa=, 116, =124=.
=P. tiarella=, 116, =124=.
=Pennatula=, =141=.
=P. aculeata=, Plate XLVII.
=P. borealis=, Plate XLVII.
=Pennatulacea=, 141, =153=.
=Pentaceros=, 204, =210=.
=P. occidentalis=, 204, =210=.
=P. reticularis=, 204, =210=.
=Pentacerotidæ=, 204, =210=.
=Pentacrinus=, 234, =235=.
=Pentacta=, 228, =232=.
=P. frondosa=, 43, 228, =232=.
=Pentagonasteridæ=, 204, =209=.
Pericardium, =341=, 416.
=Pericolpa=, 133, =136=.
=P. quadrigata=, 133, =136=.
=Peridinieæ=, 38.
=Periostracum=, =303=, 425.
Perisaltic, 172.
Perisarc, 118, =119=.
Peristome, =190=, 194, 218, =303=.
Peristomium, =176=.
Periwinkles, =371=.
=Perna=, 405, =432=.
=P. ephippium=, 405, =432=.
=Peromedusæ=, 133, =136=.
=Petricola=, 407, =452=.
=P. carditoides=, 407, =452=.
=P. pholadiformis=, 407, =452=.
=Petricolidæ=, 407, =452=.
=Petrocelis=, 78, =95=.
=P. cruenta=, 40, 78, =95=.
=Petrolisthes=, 240, =270=.
=P. armatus=, 240, =270=.
=P. sexspinosus=, 240, =270=.
=Peyssonnelia=, 78, =95=.
=P. Dubyi=, 78, =95=.
=Phæophyceæ=, 28, 61, 62.
Phanerogams, 25.
=Phanerozonia=, =204=, =208=.
=Phascolosoma=, 162, =186=.
=P. Gouldii=, 162, =186=.
=Pholadidæ=, 407, =460=.
=Pholas=, 407, =460=.
=P. californica=, 407, =461=.
=P. costata=, 407, =461=.
=P. truncata=, 407, =461=.
=Phoxichilidium=, 242, =297=.
=P. maxillare=, 242, =297=.
=Phyla=, =19=.
=Phyllitis=, 62, =66=.
=P. fascia=, 62, =66=.
=Phyllodoce=, 161, =175=.
=P. gracilis=, 161, =175=.
=Phyllodocidæ=, 161, =175=.
=Phyllolithodes=, 240, =271=.
=P. papillosus=, 240, =271=.
=Phyllonotus pomum=, =382=.
=Phyllophora=, 76, =81=.
=P. Brodiæi=, 76, =82=.
=P. membranifolia=, 76, =82=.
=Phyllopoda=, =238=.
=Phyllospora=, 63, =73=.
=P. Menziesii=, 63, =73=.
Phylum, 19.
=Phyncopodia helianthoides=, =207=.
=Physalia=, =131=.
=P. arethusa=, 117, =131=.
=Pikea=, 78, 94.
=P. californica=, 78, =94=.
Pill-bugs, =291=.
=Pinna=, 405, =431=.
=P. muricata=, 405, =431=.
=P. seminuda=, 405, =431=.
=Pinnotheres=, 241, =287=.
=P. maculatum=, =287=.
=P. ostreum=, 241, =287=.
=Pinnotheriidæ=, 241, =287=.
=Pitho=, 241, =286=.
=P. aculeata=, 241, =286=.
=Placunanomia=, 405, =425=.
=P. macrochisma=, 405, =425=.
=Planaria=, 160, =167=.
=P. grisea=, 160, =167=.
Planarians, =166=.
Planarian worms, 12.
Plankton, =21=, 23.
=Planocera=, 160, =166=.
=P. nebulosa=, 160, =166=.
=Planula=, 120, =135=.
=Platyhelminthes=, 159, 160, =164=.
=Platyonichus ocellatus=, =276=.
=Pleurobrachia=, 154, =156=.
=P. rhododactyla=, 154, =156=.
=Pleurococcus=, 26.
=P. vulgaris=, =25=.
=Plocamium=, 77, =85=.
=P. coccineum=, 77, =85=.
=Plumularia=, =127=.
=P. falcata=, 116, =127=.
Plumularians, 116, =127=.
Pluteus, 201, =220=.
Polian vessels, 201.
=Polina=, 160, =170=.
=P. glutinosa=, 160, =170=.
=Polychæta=, 161, =172=.
=Polycirrus=, 161, =182=.
=P. eximius=, 161, =182=.
=Polycladida=, 160, =165=.
=Polyides=, 78, =95=.
=P. rotundus=, 78, =95=.
=Polymastia=, 100, =106=.
=P. robusta=, 100, =106=.
=Polynices=, 12, 310, 314, 325, 335, =367=.
=P. duplicata=, 11, 325, 344, =367=.
=P. heros=, 8, 10, 44, 325, 343, =367=.
=P. lewisii=, 325, =368=.
=P. recluziana=, 325, =368=.
=P. triseriata=, 325, =367=.
=Polynoë=, 161, =174=.
=P. squamata=, 161, =174=.
=P. sublevis=, 161, =174=.
=Polyphemus=, =238=.
Polypide, 190, =192=.
=Polyplacophora=, 300, =321=.
Polyps, 111, =114=, 119.
=Polysiphonia=, 77, =87=.
=P. Baileyi=, 77, =88=.
=P. dendroidea=, 77, =87=.
=P. fastigiata=, 43, 77, =87=.
=P. fibrillosa=, 77, =88=.
=P. Harveyi=, 77, =88=.
=P. nigrescens=, 77, =87=.
=P. Olneyi=, 77, =88=.
=P. parasitica=, 77, =87=.
=P. urceolata=, 77, =88=.
=P. urceolata=, var. =formosa=, 77, =88=.
=P. variegata=, 77, =88=.
=P. violacea=, 44, 77, =88=.
=P. Woodii=, 77, =89=.
=Polyzoa=, 8, 188, =191=.
Polyzoans, 8, 12, 22.
=Pontonema=, 161, 170.
=P. marinum=, 161, =170=.
Porcelanous, =304=, 345.
=Porcellana=, 240, =269=.
=P. sayana=, 240, =269=.
=Porcellanasteridæ=, 204, =208=.
=Porcellanidæ=, 240, =269=.
Porcupine Island, =42=.
=Porifera=, 100, =101=.
=Porites=, =147=.
=P. astræaoides=, Plate XLV.
=P. furcata=, Plate XLV.
=Porocidaris=, 217, =222=.
=P. sharreri=, 217, =222=.
=Porphyra=, 43, 78, =96=.
=P. laciniata=, 78, =96=.
=P. vulgaris=, 38, 78, =96=.
=Porpita=, =132=.
=Portunidæ=, 241, =274=.
Prawns, 258, =259=.
Preserving invertebrates, =14=.
=Prionitis=, 78, 94.
=P. Andersonii=, 78, =94=.
=P. lanceolata=, 78, =94=.
Proboscis, =333=.
=Procerodes=, 160, =167=.
=P. frequens=, 160, =167=.
Propodium, =335=.
=Prosobranchiata=, 300, 324, 349, =355=.
Prostomium, =176=, 243.
=Protista=, =22=.
=Protobranchiata=, 301, 405, 420, =421=.
=Protococcaceæ=, 38.
=Protococcus nivalis=, 25, =33=.
=Protophyta=, =21=.
=Protozoa=, =21=, 101.
=Pseudolamellibranchiata=, 301, 405, 420, =429=.
=Psilaster=, 204, =209=.
=P. floræ=, 204, =209=.
=Psolus ephippiger=, =231=.
=P. fabricii=, =232=.
=Pterogorgia acerosa=, Plate XLVI.
=Pteronotus=, 326, =384=.
=P. festivus=, 326, =384=.
=Ptilota=, 78, =92=.
=P. densa=, 78, =92=.
=P. elegans=, 78, =92=.
=P. hypnoides=, 78, =92=.
=P. serrata=, 78, =92=.
=Pugettia=, 241, =285=.
=P. gracilis=, 241, =285=.
=Pulmonata=, 300, 331, 338, =349=.
=Punctaria=, 62, =65=.
=P. latifolia=, 62, =65=.
=P. plantaginea=, 62, =66=.
=P. tenuissima=, 62, =66=.
=Purpura=, 8, 9, 309, 312, 326, =386=, 387.
=P. crispata=, 326, =387=.
=P. hæmastoma=, 326, =387=.
=P. lapillus=, 41, 42, 314, 326, =386=.
=P. lima=, 326, =387=.
=P. patula=, 326, =386=.
=P. saxicola=, 326, =387=.
=Purpurinæ=, 326, =385=.
=Pycnogonida=, 242, =296=.
=Pycnogonidæ=, 9.
=Pylopagurus=, =268=.
Pyloric cæca, =208=.
=Pyrocystis noctiluca=, =33=.
=Pyrosoma=, 472.
=Pyrosomata=, 472.
=Pyrula=, 10, 326, =379=.
=P. papyratia=, 326, =379=.
R
=Radiata=, =113=.
Radiates, 20.
Radula, 304, =317=, =340=.
=Ræta=, 406, =447=.
=R. canaliculata=, 406, =447=.
=Ralfsia=, 62, =65=.
=Ralfsiaceæ=, 62, =65=.
=Rataria=, =132=.
Receptacles, =72=.
Red crab, =278=.
Red seaweeds, 76, =79=.
Red snow, =33=.
Reef-builders, =147=.
Reef-corals, 142, =146=.
=Regularia=, 217.
Reticulated, =304=.
=Rhabdocœlida=, 160, =167=.
=Rhabdonia=. 77, =83=.
=R. Coulteri=, 77, =84=.
=R. tenera=, 77, =83=.
=Rhithropanopeus=, 241.
=R. harrisii=, 241, =281=.
=Rhizocephala=, 239, =256=.
=Rhizophyllideæ=, 78, =95=.
=Rhizostomæ=, 133, =139=.
=Rhodactinia=, 141, =145=.
=R. davidsii=, 141, =145=.
=Rhodomela=, 77, =89=.
=R. floccosa=, 77, =90=.
=R. larix=, 77, =90=.
=R. Rochei=, 77, =89=.
=R. subfusca=, 77, =89=.
=Rhodomeleæ=, 77, =86=.
=Rhodophyceæ=, 28, 76, =79=.
=Rhodophyllideæ=, 77, =83=.
=Rhodophyllis=, 77, =83=.
=R. veprecula=, 77, =83=.
=Rhodospermeæ=, 79.
=Rhodymenia=, 77, =85=.
=R. palmata=, 38, 42, 43, 77, =85=.
=Rhodymeniaceæ=, 77, =84=.
=Rhodymenieæ=, 77, =85=.
Ring-canal, 201, =203=.
Rock-crab, 277, =280=.
Rockweeds, =8=.
Rocky shores, =7=.
Rodicks Weir, 44.
Root-mouth jellyfishes, =139=.
Rostrum, 243.
Roundworms, =170=.
S
=Sabella=, 162, =184=.
=S. microphthalma=, 162, =184=.
=Sabellidæ=, 162, =184=.
=Sacculina=, =239=, =256=.
=Sagartia=, 141, =145=.
=S. leucolena=, 141, =145=.
=Salpa=, 472, 474, =475=.
Sand-crab, =282=.
Sand-dollar, 11, 44, =225=.
Sandpiper, =5=.
Sandy shores, =10=.
=Sapphirina=, 239, =250=.
Sargasso Sea, =33=.
=Sargassum=, 26, 63, 64, =73=.
=S. bacciferum=, 34, 35, 63, =74=.
=S. Montagnei=, 63, =74=.
=S. vulgare=, 63, =74=.
=Sarsia=, 116, =123=.
=S. mirabilis=, =123=.
=Saxicava=, 41.
=Saxidomus=, 406, =452=.
=S. nuttallii=, 406, =452=.
=Scala=, 325, =365=.
=S. angulata=, 325, =366=.
=S. groenlandica=, 325, =366=.
=S. lineata=, 325, =366=.
=S. multistriata=, 325, =366=.
=Scalidæ=, 325, =365=.
Scallops, 12.
=Scaphopoda=, 320, 321, 327, =402=.
=Schizaster=, 217, =227=.
=S. fragilis=, 217, =227=.
=Schizopoda=, 239, =257=.
=Scinaia=, 76, =80=.
=S. furcellata=, 76, =80=.
=Scrobicularia=, 413.
Sculpture, =304=.
=Scurria=, 312.
Scuta, =254=.
=Scutellidæ=, 217, =225=.
=Scyllarus=, 258, =263=.
=Scyphozoa=, 112, 115, 133, =134=.
Sea-acorns, =254=.
Sea-anemones, 112, =142=.
Sea-blubbers, 134.
Sea-colanders, 42, =69=.
Sea-cucumbers, 43, 200, 202, =229=.
Sea-eggs, =221=.
Sea-fans, 114, 115, 142, 147, =152=.
Sea-feathers, =152=.
Sea-hares, =351=.
Sea-lilies, 200, =234=.
Sea-mats, =192=.
Sea-otters' cabbage, =35=.
Sea-peach, =476=.
Sea-pens, 142, =153=.
Sea-slugs, =349=.
Sea-spiders, 9, =296=.
Sea-squirts, =474=.
Sea-urchins, 43, 114, 200, 203, =218=, 220.
Sea-whips, 142, =152=.
=Sedentaria=, 161, =180=.
Segment, 243.
Segmented worms, =170=.
=Semostomæ=, 133, =137=.
Sense-organs, =135=.
=Sepia=, 464, 467, 468.
=Septibranchiata=, 420.
=Serpula=, 162, =185=.
=S. dianthus=, 162, =185=.
=Serpulidæ=, 162, =184=.
=Sertularia=, =126=.
=S. argentea=, 43, 116, =127=.
=S. cupressina=, 116, =127=.
=S. pumila=, 43, 116, =126=.
Sertularians, 8, 116, 120, 121, =126=.
Sessile, 121, 126.
Sheep-crab, =285=.
Sheepswool sponge, 104, =108=.
Shell—
Butterfly-, 323.
Coffee-, 379.
Conch-, 377.
Cowry-, 377.
Gasteropod, =342=.
Growth of gasteropod, 346.
Mounds, 432.
Noah's-ark, 426.
Peach-, 454.
Pelecypod, =416=, 417.
Razor-, 457.
Setting-sun, 444.
Shipworm, 462.
Shrimps, =240=, 245, 258, =259=.
=Sigaretus=, 311, 325, 334, =369=.
=S. perspectivus=, 325, =369=.
Signs on the beach, =1=.
Singing Beach, =2=.
Sinistral, 304, =345=.
Sinuate, 304.
=Sipho=, 309, 313, 327, =393=.
=S. islandicus=, =393=.
=S. pygmæus=, 327, =394=.
=S. Stimpsoni=, 327, =393=.
Siphon, 304, =330=, 334, =411=.
Anal, 412.
Branchial, 412.
Excurrent, 412.
Functional, 411.
Incurrent, 412.
=Siphonalia=, 327, =394=.
=S. kellettii=, 327, =394=.
=Siphoneæ=, 51, =56=.
Siphonoglyphs, =143=.
=Siphonophora=, 117, 120, =121=, =130=.
Siphonozoöids, =150=.
Siphuncle, 468.
=Sipunculoidea=, 162, =185=.
=Sipunculus=, 162, =185=.
=S. nudus=, 162, =185=.
Skates, 12, 44.
=Solaster=, 204, 205, =211=.
=S. decemradiata=, 204, =211=.
=S. endeca=, 204, =211=.
=Solasteridæ=, 204, =211=.
=Solen=, 407, =458=.
=S. ensis=, 3, =458=.
=S. rosaceus=, 407, =458=.
=S. sicarius=, 407, =458=.
=S. viridis=, 407, =458=.
=Solenidæ=, 407, =457=.
=Solenogastres=, 321.
=Solenomya=, 405, =423=.
=S. borealis=, 405, =423=.
=S. velum= 405, =423=.
=Solenomyidæ=, 405, =423=.
Somite, 243.
Sow-bugs, =291=.
=Spatangoidæ=, 217, =226=.
=Spatangoidea=, 217, =226=.
Species, 20.
Specific name, 28.
=Sphacelaria=, 62, =65=.
=S. cirrhosa=, 62, =65=.
=S. radicans=, 62, =65=.
=Sphacelariaceæ=, 62, =65=.
=Sphæoplea annulina=, 37.
Sphæridia, 219.
=Sphærococceæ=, 77, =84=.
=Sphæroma=, 242, =293=.
=S. destructor=, =293=.
=S. quadridentatum=, 242, =293=.
Spicules, 102.
Spider-crabs, 241, =284=.
Spines, 201, 205, 221.
=Spionidæ=, 161, =181=.
Spire, 304.
=Spirorbis=, 8, 12, 162, =185=.
=S. borealis=, 162, =185=.
=Spirula=, 464, 467, 468.
=Spirulina=, 48, =49=.
Sponges, 100, =101=.
=Spongia=, =104=.
=S. graminea=, =109=.
=Spongidæ=, 100.
=Spongillidæ=, =104=.
Spongin, =102=.
Spring-tides, =13=, 15.
=Spyridia=, 78, =92=.
=S. filamentosa=, 78, =92=.
=Squamarieæ=, 78, =95=.
Squame, 243.
Squids, 464.
=Squilla=, 241, =288=.
=S. empusa=, 241, =288=.
Starfishes, 43, 114, 200, 203, 204, =205=, 434.
Station and habits of the Mollusca, =313=.
=Stauromedusæ=, 133, =136=.
=Stelosponginæ=, 100.
=Sternogramme=, 76, =82=.
=S. interrupta=, 76, =82=.
=Sternorhynchus=, 241, =286=.
=S. sagittarius=, 241, =286=.
=Stomatopoda=, 241, =288=.
Stone-canal, 201, =203=.
Stone-crab, =280=.
Stony corals, 112, 115, =146=.
Striæ, =344=.
Strobila, =135=, 138.
=Strombidæ=, 326, =375=.
=Strombus=, 10, 311, 326, =376=.
=S. alatus=, =376=.
=S. gigas=, 326, =376=, 431.
=S. pugilis=, 326, =376=.
=Strongylocentrotus=, 217, =223=.
=S. drobachiensis=, 41, 43, 217, =223=.
=S. franciscanus=, 217, =223=.
=S. purpuratus=, 217, 221, =223=.
Structure of mollusks, =315=.
=Stylochopsis=, 160, =166=.
=S. littoralis, 160=, =166=.
=Suberites=, 100, =106=.
=S. compacta=, 100, =106=.
=Suberitidæ=, 100.
Suborders, 29.
Subumbrella, =120=.
Suckers, 201, =203=.
Sun-jellies, 134, =138=.
Suture, 304, =344=.
Swimming-bell, 120.
Swimming crabs, 241.
=Syconidæ=, 100.
=Syllidæ=, 161, =173=.
Symmetry, =328=.
=Synapta=, 228, 229, =233=.
=S. roseola=, 228, =233=.
=S. rotifera=, 228, =233=.
=S. tenuis=, 228, =233=.
=S. viviparia=, =231=.
T
Table: Classification of algæ—
Blue-green, =48=.
Brown, =62=.
Grass-green, =51=.
Red, =76=.
Classification of—
Actinozoa, =141=.
Arthropoda, =238=.
Asteroidea, =204=.
Cephalopoda, =464=.
Chordata, =472=.
Ctenophora, =154=.
Echinoidea, =217=.
Holothuroidea, =228=.
Hydrozoa, =116=.
Mollusca, =300=.
Molluscoida, =188=.
Ophiuroidea, =213=.
Pelecypoda, =409=.
Porifera, =100=.
Scyphozoa, =133=.
=Tagelus=, 310, 407, =459=.
=T. gibbus=, 407, =459=.
=Talitrus longicornis=, =289=.
=Talorchestia=, 242, =289=.
=T. longicornis=, 242, =289=.
=T. megalophthalma=, =290=.
=Taonia=, 63, =71=.
=T. atomaria=, 63, =71=.
=Tapes=, 406, =451=.
=T. laciniata=, 406, =451=.
=T. staminea=, 406, =451=.
=Tealia crassiformis=, =145=.
=Tectarius=, 311, 326, =373=.
=T. muricatus=, 326.
=T. nodulosus=, 326, =373=.
=Tectibranchiata=, 300, 324, =350=.
=Tedania=, 100, =107=.
Teeth, =304=, 417, 418.
Cardinal, 418.
Lateral, 418.
=Tellina=, 311, 406, =443=.
=T. alternata=, 406, =444=.
=T. bodegensis=, 406, =444=.
=T. radiata=, 406, 443, =444=.
=T. tenera=, 406, =444=.
=Tellinidæ=, 406, =443=.
Telson, 243, =247=.
Tentaculocysts, =135=.
=Terebellidæ=, 161, =182=.
=Teredinidæ=, 407, =462=.
=Teredo=, 407, =462=.
=T. navalis=, 13, 407, =462=.
Terga, =254=.
Terms used in describing Crustacea, =243=.
Echinoderms, =201=.
Hydroids, =118=.
Mollusks, =302=.
Polyzoa, =190=.
Testaceous, =304=.
=Tetrabranchiata=, 301, 464, =467=.
=Tetrastemma=, 160, =169=.
=T. arenicola=, 160, =169=.
=Thalassiophyllum=, =36=, 63, 70.
=Thaliacea=, 472.
Thallophytes, 25.
Thallus, 26.
=Thelepsus=, 161, =182=.
=T. cincinnatus=, 161, =182=.
Thorax, 243, =246=.
=Thracia=, 309.
=Thyone=, 228, =231=.
=T. briareus=, 228, =231=.
=Tima=, =128=.
=T. formosa=, 116, =128=.
=Tivela=, 406, 410, =450=.
=T. crassatelloides=, 406, =450=.
Toad-crab, =285=.
=Toxopneustes=, 217, =224=.
=T. variegatus=, 217, =234=.
=Trachylinæ=, 117, 120, =128=.
=Trachymedusæ=, 117, =128=.
=Trachynema=, =128=.
=T. digitale=, 117, =128=.
Transatlantic province, =309=.
=Trematoda=, =160=.
=Trichodesmium=, =33=.
=Trichotropis=, 309.
=Tricladida=, 160, =166=.
Triclads, =166=.
=Tridacna gigas=, 313, =419=.
=Triforis=, =374=.
=Tritonidea=, 327, =394=.
=T. tincta=, 327, =394=.
=Trivia=, 326, =378=.
=T. californica=, 326, =379=.
=T. pediculus=, 326, =378=.
=T. quadripunctata=, 326, =379=.
=T. solandri=, 326, =379=.
=T. spadacea=, =379=.
=Trochidae=, 325, =359=.
=Trochiscus=, 325, =362=.
=T. norrisi=, 325, =362=.
=Trophon=, 309, 326, =383=.
=T. clathratus=, 326, =383=.
Tube-feet, =203=.
=Tubicola=, 161, =172=.
Tubicolous worms, =180=.
=Tubipora=, 141, 147, =151=.
=Tubularia=, 116.
=T. Couthouyi=, 116, =123=.
=T. indivisa=, 116.
Tubularians, 116, 121, =122=.
=Tubulipora=, 188, =194=.
=T. flabellaris=, 188, =194=.
=Tunicata=, 472. =474=.
Tunicates, 474.
=Turbellaria=, 160, =165=.
Turbinate, =304=.
=Turbinellidæ=, 327, 394.
=Turbinidæ=, 325, =362=.
=Turbo=, 325, =363=.
=T. castaneus=, 325, =363=.
=T. castaneus, var. crenulatus=, 325, =363=.
Tyrian purple, 386.
U
=Uca=, 241, =282=.
=U. minax=, 241, =282=.
=U. pugilator=, 241, =282=.
=U. pugnax=, 241, =282=.
=Udotea=, 51, =58=.
=U. conglutinata=, 51, =58=.
=U. flabellata=, 51, =58=.
=Udoteaceæ=, 51, =58=.
=Ulothrix=, 51, =53=.
=Ulva=, 26, 28, 29, 51, =55=.
=U. lactuca=, 51, =55=.
=U. latissima=, 51, =55=.
=U. Linza=, =56=.
=U. rigida=, =55=.
=Ulvaceæ=, 28, 51, 52, 53, =54=.
Umbilicus, 304, =344=.
Umbo, 304, 417.
Uncini, 180.
Univalves, =306=, 307, 314.
=Urochorda=, 472, =474=.
=Urosalpinx=, 11, 326, =383=, 434.
=U. cinerea=, 314, 326, =383=.
Uses of algæ, =37=.
V
=Valoniaceæ=, 51, =56=.
Valve, =409=, 416.
Varices, 304, 344, =347=.
Vegetative reproduction, 27.
=Vellela=, =131=.
=V. limbosa=, 117, =131=.
Velum, =134=.
=Velutina=, 309.
Velvet sponge, 104.
=Veneridæ=, 406, =447=.
Venons sinuses, =247=.
Ventral surface, 201.
Ventricose, =304=.
=Venus=, 406, 410, =448=.
=V. cancellata=, 406, =449=.
=V. mercenaria=, 406, =448=.
=V. mercenaria, var. mortoni=, 406, =449=.
Venus's flower-basket, =102=.
Girdle, =157=.
=Vermes=, =163=.
=Vermetidæ=, 326, =375=.
=Vermicularia=, 326, =375=.
=V. spirata=, 326, =375=.
Vertebrates, =19=.
=Vesicularia=, 189, =198=.
=V. custata=, 189, =198=.
=V. dichotoma=, 189, =198=.
Vibracula, 190, =193=.
Visceral mass, 415.
=Voluta=, 313, 327, =398=.
=V. junonia=, 327, 398, =399=.
=Volutidæ=, 327, =398=.
Vulgar names, 29.
W
Walking crabs, =241=.
Water-vascular system, 201, 202, =206=, 231.
West Indian division, 24.
Wharves and bridges, 13.
Whelks, 44.
Whorl, 304, =343=.
Whorls, nepionic, 344.
Worms, 159, =163=.
Bristle-, 171.
Chætopod, 172.
Clam-, 176.
Flat-, 164.
Nemertean, 167, 169.
Polychæte, 172.
Polyclad, 165.
Round-, 170.
Segmented, 170.
Tubicolous, 180.
X
=Xiphosura=, 242, =294=.
=Xylotrya=, 462.
Y
Yellow sponge, 104.
=Yoldia=, 309, 405, =422=.
=Y. limatula=, 405, =422=.
=Y. sapotilla=, 405, =423=.
=Y. thraciæformis=, 405, =432=.
Z
=Zirphæa=, 407, =461=.
=Z. crispata=, 407, =461=.
=Zoantharia=, 141, =142=.
Zoarium, 190, =192=.
=Zoëa=, =248=, 263, 273.
Zoœcium, 190, =192=.
=Zonaria=, 63, =70=.
=Z. lobata=, 63, =70=.
Zoöids, 118, =119=.
Zoöphytes, 113, 119.
=Zostera marina=, 12.
=Zygodactyla=, =128=.
=Z. groenlandica=, 116, =128=.
CORRIGENDA
Page 6. Second line from the bottom, for "they" read: Anemones.
41. Line 20, for "/mœnas/" read: /mænas/.
43. Last line, for "they" read: animals.
44. Line 27, for "/Cyania/" read: /Cyanea/.
102. Last line, for "/flagellæte/" read: /flagellate/.
196. Line 27, for "species" read: specimens.
224. Line 16, for "/lunales/" read: /lunules/.
Plate LXXXIV, 6. For "/Glvcimeris/" read: /Glycimeris/.
TRANSCRIBER'S NOTE
The original text has been retained as printed, with some exceptions.
Illustrations have been moved from within paragraphs to nearby
spots between paragraphs. Page numbers from the printed 1901
edition are indicated like this: "[pg235]".
As mentioned on page 29 of the book, typography was used in a
specific way to visually distinguish various taxonomic classes.
This simple text edition will indicate text that was originally
printed with both small-caps and bold applied with "~", e.g.
"Suborder ~CHÆTANGIEÆ~". Text that originally had both italics
and bold applied is indicated herein by "^". Thus "Species ^L.
majuscula^". Text that was originally small-caps with or without
bold is all uppercase. Text that was originally italics without
bold is displayed herein with "/", thus "Genus /Griffithsia/". Text
that was originally bold without italics or small caps is indicated
with "=", thus "Class =ALGÆ=". The original variations in font-size
are not carried into this version.
Many of the biological classification schemes shown in this book were
printed with large curly brackets "{" extending several lines high.
For example, on page 18, a classification scheme was printed similar
to this:
/Rhodymeniaceæ/, {/Callithamnion/
suborder {/Griffithsia/
/Ceramieæ/ {/Ceramium/
except that the three "{" were not printed, but were replaced by
a single tall "{". This typography does not generally work well
in current electronic books. Therefore, tables or schemes of this
sort have (except on page 18) been replaced by a different format
(nested list with tables) employing rearrangement and indentation,
without curly brackets—like this:
Order /Rhodymeniaceæ/
Suborder /Ceramieæ/
Genera
/Callithamnion/
/Griffithsia/
/Ceramium/
There are rare instances when this could cause confusion. For
example, the partial paragraph that preceeds the page 18 example
shown above:
The genera of an order are then placed within a cover and labeled
in the same way, the legend then having the name of the order on
the left and the genera on the right of the bracket, thus:
refers to a bracket no longer present in this version, and "left" and
"right" are perhaps no longer meaningful.
Page 102: "flagellœte Infusoria" was changed to "flagellate
Infusoria" to match the corresponding index entry.
Page 150: in "The strictures forming the lobes", changed "strictures"
to "structures".
Page 154: changed "rhododaciyla" to "rhododactyla".
Page 172: changed "perisaltic" to "peristaltic".
Page 188: in the table showing the classification of the Mulluscoida,
there are grouping words such as "Articulata", "Inarticulata", and
"Flustrina", which are not labeled as to whether they are taxonomic
"Family", or some other class. The transcriber has chosen to label
them "Set", which term is not elsewhere used in the book to denote a
formal taxonomic class. The same sort of thing is done on a few other
pages, e.g. on page 240, for the group "Free-swimming Forms".
Page 196: "Phyllopora" changed to "Phyllophora"—a guess.
Page 216 (facing), Plate LV.: "Ophiocoma œthiops" changed to
"Ophiocoma æthiops".
Page 233: "rows" to "Rows", in "rows of tube-feet lie near together,".
Page 239, and perhaps elsewhere: notes such as "without gills or
thoracic legs" that were printed with the Genera, in this example
/Mysis/, have been moved into the note attached to a next higher
taxonomic class, i.e. Order Schizopoda, with added text necessary for
clarification.
Page 362: "f dation" to "foundation" in "greenish-white nacreous
f dation".
Page 486: the index entry "Pacific faunal divisions" had no page
number. The number "=311=" seems correct, and has been inserted.
Index, "Endendrium ramosum, Plate XLI." entry is removed, and "Plate
XLI" is added to entry "Eudendrium ramosum".
Index, entry "Ventricosa" changed to "Ventricose".
Corrigenda: The corrections listed therein have been applied to the
text. In addition to the listed corrections, there were two other
instances of "lunales", on pp 225 and 226, now changed to "lunules";
also "lunale" to "lunule" on p 225.
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