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Title: A Bilateral Division of the Parietal Bone in a Chimpanzee; with a Special Reference to the Oblique Sutures in the Parietal
Author: Hrdlička, Aleš, 1869-1943
Language: English
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Copyright Status: Not copyrighted in the United States. If you live elsewhere check the laws of your country before downloading this ebook. See comments about copyright issues at end of book.

*** Start of this Doctrine Publishing Corporation Digital Book "A Bilateral Division of the Parietal Bone in a Chimpanzee; with a Special Reference to the Oblique Sutures in the Parietal" ***

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  _A Bilateral Division of the Parietal Bone
       in a Chimpanzee; with a Special Reference
       to the Oblique Sutures in the


  _American Museum of Natural History_,
  VOL. XIII, ARTICLE XXI, pp. 281-295.

  _New York, Dec. 31, 1900._

  _The Knickerbocker Press, New York_



The first to describe a case of division of the parietal bone in apes
was Johannes Ranke, in 1899.[1] The skull in question is that of an
adolescent female orang, one of 245 orang crania in the Selenka
collection in the Munich Anthropological Institute. The abnormal
suture divides the right parietal into an upper larger and a lower
smaller portion. "The suture runs nearly parallel with the sagittal
suture," but, as the illustration shows (Fig. 1), it descends in its
posterior extremity towards the temporo-parietal suture, and
terminates in this a few millimetres in front of the lambdoid suture.
The abnormal suture shows but little serration, and the articulation
of the two divisions of the parietal bone is squamous in character,
the lower portion overlapping the upper. Below the junction of the
abnormal with the coronal suture, the latter takes a pronounced bend
forward. A similar bend in the coronal suture is present in the same
specimen on the left side. This is common among the other orang skulls
in the collection. The portions of the coronal suture below and above
the bend differ somewhat in character.

Besides the above-mentioned complete division, Ranke found among the
245 orang skulls 13 with incomplete division of the parietal bone. The
division consisted invariably of a longer or shorter remnant of a
horizontal "parietal suture," ending in the coronal suture at the top
of the bend above referred to. A similar anterior remnant of an
abnormal parietal suture was found by Ranke in a young chimpanzee
skull; but the author questions the word "chimpanzee," which evidently
means that the identity of the skull is somewhat doubtful.

In consequence of his finds, Ranke believes both complete and
incomplete divisions in the parietal bone to be much more frequent in
the orang than in man.[2] He also thinks that the bend usually present
in the coronal suture in the orang signifies that, "even where there
are no traces of a parietal suture, such a suture has actually existed
in an earlier stage of development." This implies the development of
the adult parietal bone in the orang from two original segments, one
above the other.

[Illustration: Fig. 1. Division of the Right Parietal in an Orang
(Ranke, Abh. d. k. bayer. Akad. d. Wiss., II cl., XX Bd., ii Abth.).]

The divisions which I am about to describe occur, one in each
parietal, in the skull of a nine-year-old male chimpanzee, which was
captured, when young, in West Africa. Later on he was one of the
attractions of the Barnum and Bailey Circus, and was familiarly known
as Chico. The chimpanzee died in 1894, since when his skin and bones
have been preserved in the American Museum of Natural History, New
York City. Prof. J. A. Allen, the curator of the Zoölogical Department
of the Museum, has kindly given me permission to describe the skeletal
parts for publication.[3]

The most interesting part of Chico is unquestionably the skull. The
divisions of the parietal bones which the specimen presents are not
only the first complete divisions of the parietal observed in a
chimpanzee, but are also unique in character, no divisions of the same
nature having been observed before, either in man, in apes, or in
monkeys. The position and extent of the divisions in this skull will
throw considerable light on the question of the aberrant, complete
divisions of the parietal bone, by which term may be designated
divisions differing from the typical horizontal ones.

The skull under consideration shows in general a good development and
an almost perfect symmetry. The capacity of the brain cavity, measured
according to Flower's method, is 390 c.c.

The masculine features of this skull, and particularly the temporal
ridges, are not quite as marked as those of another skull of an
adolescent male chimpanzee in the Museum. The temporal ridges are
slightly prominent, and in their middle third, over part of the frontal
and the parietal bones, not more pronounced than in some human crania.
They are, however, situated very high. Their upper lines or boundaries
touch each other over a part of the sagittal suture, a little back of
the bregma; while the lower lines approach to within 6 mm. of the
sagittal suture. The supraorbital ridges are not very massive, although
prominent to such a degree that, when the skull rests on the occipital
condyles and on the teeth, the plane of the orbits is almost vertical.
The sagittal crest is insignificant; the occipital crest is high, but
not very massive. The zygomatic arches are less strong than they are in
an average white male; and the mastoids are small, even smaller than in
an average adult white female.

The second dentition is incomplete; the third molars have not reached
the level of the opening of their sockets. The condition of the
sutures, so far as their patency is concerned, does not bear the same
relation to the stage of dentition as it does in man: all the sutures
of this skull are more or less obliterated. There are no signs on any
part of the skull that point to the closure of any of the sutures as
premature. In detail, the condition of the sutures is as follows: The
spheno-maxillary articulation is completely closed, but still plainly
traceable. Of the various facial sutures, only remnants are open; the
suture in the zygomatic arch, however, is almost fully patent on both
sides. The spheno-frontal articulation is completely obliterated on
the left, but traces of it remain on the right side. The left
temporo-sphenoidal and squamo-frontal sutures (the squama of the
temporal articulates with the frontal bone) are, with the exception of
the basal part of the former, which remains open, quite obliterated,
but on the right side both are open. The temporo-parietal sutures,
with the exception of 8 mm. of the anterior end of the suture on the
right side, are both entirely closed and hardly traceable. The coronal
suture is partly open on the left, and wholly open on the right, up to
a point a little below the middle of the anterior border of the
parietal bone. At this point on each side, the lower portion of the
coronal suture bends backward and continues as the anomalous suture;
the upper portion of the coronal, particularly on the right, is
completely obliterated, though still traceable. There are no signs
left of the sagittal and lambdoid sutures, and only the basal portions
of the temporo-occipital articulation remain. The palatine sutures,
also, are entirely obliterated.

The skull shows no important anomalies besides the division of the

The divisions of the parietal bones begin on the left 32 mm., on the
right 28 mm. (measured with a tape), above the point of junction of
the coronal and temporo-parietal sutures. From the point where the
anomalous sutures leave the coronal suture, to the bregma, the
distance on the left is 44 mm., on the right 42 mm. The excess of size
of the left over the right parietal bone along the coronal suture (6
mm.) compensates the greater height of that portion of the right
temporal squama which articulates with the frontal bone. Measured
across their middle from the temporo-parietal suture, the two
parietals appear to be almost of equal size (left 82 mm., right 80
mm.). In an antero-posterior direction, from the beginning of the
division to the middle of the parietal portion of the occipital crest,
both bones measure the same, namely 75 mm.

The division in the left parietal begins at a V-shaped cleft, which is
filled with a process of the frontal bone. There are slightly distinct
markings on the bone and a number of insular ossicles, which make it
probable that the cleft had been originally much greater and was
largely filled by a Wormian or, rather, a fontanel bone, the lower
border of which has subsequently united with the parietal.

For 30 mm. from its beginning the abnormal suture proceeds directly
backward, and to this extent shows but little obliteration. The original
cleft has, it seems, extended up to this point. From here the suture
takes a slight bend upwards, and proceeds almost directly upwards and
backwards, becoming gradually obliterated, until it disappears at the
temporal ridge, 16 mm. from the median line. Originally the suture must
have terminated on the posterior border of the parietal bone, not far
from the lambda. The whole suture shows fairly good serration. The
coronal suture on this side, below the division, shows serration about
equal to that of the abnormal suture; the obliterated portion above this
was, so far as can be seen, more simple.

[Illustration: Figs. 2-4. Skull of an Adolescent Male Chimpanzee.]

On the right side the division of the parietal may also have begun with
a cleft in the anterior border of the bone, but, owing to the advanced
state of obliteration of the upper portion of the coronal suture on this
side, the existence of the cleft cannot be fully ascertained. Here also
the abnormal suture, at first wholly open, runs for the first 26 mm.
directly backwards; at this point the suture, still quite patent, takes
a turn somewhat sharper than that on the left, and proceeds for 16 mm.
backwards and upwards; here it takes a second turn, and proceeds almost
directly upwards towards the sagittal suture. This last portion of the
abnormal suture is considerably obliterated, and on and beyond the
temporal ridge is scarcely traceable. The point at which the division
has reached the sagittal suture is situated a little behind the middle
of the latter. The abnormal as well as the open part of the coronal
suture on this side shows a simpler serration than the corresponding
sutures on the left side.

In this specimen there is on neither side any encroachment of the
lower portion of the parietal bone upon the frontal, such as Ranke
lays stress on in the case of his orangs. A second skull of an
adolescent male chimpanzee, in the Museum of Natural History, has a
decided bend in the coronal suture, not unlike that which Ranke
describes, and which, as he thinks, generally indicates an old
parietal division; but in this case the bend is situated between the
inferior and superior boundaries of the prominent temporal ridge, and
apparently owes its origin to the latter (Figs. 2, 3, 4).

The main interest in the case just described centres in the direction
of the abnormal sutures, and in the clearness with which the two
divisions appear as equivalent and of the same origin, although one
divides the parietal completely, while the other is restricted to one
of its angles.

As to the course of the abnormal suture in the parietal bone, in all
the cases thus far reported, the division runs in a horizontal
direction (cases of Tarin, Soemmering, Gruber, Hyrtl, Welcker, Turner,
Putnam, Dorsey, Ranke, and others); or it runs obliquely from or near
the middle of the lambdoid suture to some part of the temporo-parietal
suture, the sphenoidal angle, or the lower portion of the coronal
suture (cases of Curnow, Ekmark, Gruber, Hyrtl, Lucae, Welcker,
Putnam, Traquair, Ranke); in a case of _Simia silenus_ described by
Gruber and in an Egyptian cranium described by Smith, the divisions
run to the lambda and begin respectively slightly above the pterion
and at it. In Boyd's and in two of Hyrtl's cases, the abnormal suture
begins at or below the bregma on the coronal margin of the parietal
bone, and ends at or near its mastoid angle; finally, in Blumenbach's
(cited by Welcker), Bianchi's, Fusari's, and Coraini's cases (those of
Coraini include two monkeys) the division is vertical, passing between
the temporo-parietal and sagittal sutures. The left division in our
chimpanzee approaches those in Gruber's _Simia silenus_ and Smith's
cases; but it originates much higher anteriorly, and terminates
slightly below the lambda on the occipital border of the parietal. The
division in the right parietal of the chimpanzee, beginning slightly
below the middle of the anterior border of the bone, and ending
slightly back of the middle of its sagittal border, has no analogy
among the cases previously described.

The difference in extent and terminations of the two abnormal sutures
in the chimpanzee is of particular interest in connection with the
problem of the significance and origin of those divisions of the
parietal bone that involve more or less only one of its angles.

Since the observations of Toldt,[4] and more recently of Ranke,[5] on
the development of the parietal bone in the human embryo, it appears,
though it cannot as yet be said whether the fact is or is not general,
that the bone originates from two centres of ossification. These
centres appear in most cases one directly above the other, but, as
Ranke himself shows,[6] and as can hardly be otherwise, these
primitive components of the parietal do not always show the same
relations in size or position. The centres blend together, ordinarily,
at the end of the third or during the first half of the fourth month
of fœtal life. On this account, the typical, complete, horizontal
division of the human parietal bone, when met with at any time after
the fourth month of fœtal life, is generally interpreted to-day as
a retardation of the union, or a persistence of separation, of the two
original segments of the bone. Opinion, however, is still unsettled as
to the significance of the more atypical, oblique divisions of the
parietal, particularly of those where the separation is limited to one
angle. Up to the recent contribution on the subject by Ranke, the
weight of opinion on the point, although rather briefly expressed,
seems to have been in favor of attributing to these smaller, oblique
divisions, the same significance as was given to the more typical,
horizontal ones. Gruber,[7] in reporting a new case of a bilateral
oblique suture in the parietal bone, calls the separated mastoid
angles "the secondary posterior parietals." Hyrtl and Welcker advance
no definite theories on this point, though the latter expresses an
opinion[8] that in both the horizontal division and the separation of
the mastoid angle of the parietal bone the development of the
condition may be identical. In 1883 Prof. F. W. Putnam, in describing
one of his Tennessee skulls with an abnormal oblique suture in each
parietal,[9] referred the development of the separated mastoid angle
on the right side, as well as the larger oblique inferior portion of
the parietal on the left side, to a "separate centre" of ossification.
Ranke[10] opposes both Gruber's and Putnam's opinion, and presents
instead a theory somewhat vague and not satisfactorily demonstrated,
by which he accounts for the origin of oblique sutures from partial
horizontal sutures in the parietal bone through "half-pathological
processes." In his words, "the oblique parietal suture is allied to
the half-pathological conditions of the skull; it is wholly
unjustifiable to speak, as W. Gruber has done, of a separate Parietale
secundarium posterius, severed by the suture, as of a typical, in a
certain sense normal, formation. The oblique parietal suture is
nothing more than an incomplete (posterior), true, _i. e._, typical,
parietal suture with a sagittal course, modified by certain
half-pathological conditions." These half-pathological conditions are
produced, the author explains on the preceding page, "durch
Einknickung der nach Herrn G. H. Meyer 'plastisch' aufwärts gebogenen
hinteren Scheitelbeinränder."

This opinion of Ranke calls for a few words about the incomplete
horizontal parietal sutures. These sutures are apparently very rare in
human adults, only five instances being on record (4 Ranke's, 1
Turner's). They are more frequent in orangs (Ranke), and quite common
(as Ranke shows, and as I found independently before Ranke's publication
of his observations) in the human embryos near term and in new-born or
very young infants. In the human family, these partial divisions of the
parietal generally begin in the posterior part, and run sagittally to
the posterior border of the bone, ending in this border at or near its
middle. In orangs the incomplete horizontal divisions seem to begin, as
a rule, in the anterior part, and end at or near the middle of the
anterior border of the parietal. The length of these divisions varies
from a few millimetres to several centimetres, and they even reach up to
the centre of the parietal bone.[11] These divisions are, without doubt,
the remains of the original anterior and posterior clefts, or, if we go
a step further, of the original intervening antero-posterior space
between the original inferior and superior segments of the parietal.
From the very first contact of the growing centres, the median extremity
of these clefts is bounded both below and above by a mass of bone; and
when the anterior or posterior border of the parietal comes finally in
contact with the frontal or occipital bone, the anterior and posterior
sagittal clefts, if they still exist, lie between two well-developed,
firm portions of the bone. Under these circumstances it is quite
impossible to imagine any disturbance, mechanical or pathological, that
could affect solely or mainly the median portion of the cleft, and cause
a deflection downward in this portion of the division, or cause its
extension to the inferior border or even the anterior-inferior angle of
the parietal.

There are only two factors that can possibly affect and modify the
course of the incomplete parietal suture, and both of these would show
their influence mainly or entirely on the distal portion of the same.
These two factors are, first, an abnormal development, either
defective or excessive, of one of the original parietal segments; and,
secondly, influences that would interfere with the freedom of full
growth of the anterior or posterior border of the parietal.

In the first case, as can easily be imagined or even artificially
demonstrated, there would be possible only a lower or higher situation
or an obliquity affecting mostly the marginal portion of the division.
The results would be low or high sagittal sutures, and curved or
oblique sutures diverging from the parietal eminence,--effects
entirely different from the actually observed oblique sutures that
sever the lower portion of the parietal, or its mastoid angle.

Influences interfering with the free development of the anterior or
posterior border of the parietal bone could only deflect upwards or
downwards the marginal end of an incomplete parietal suture, or, at
most, in a case of a short suture, render it oblique or curved in its
entirety. No pathological condition, unless it were accompanied by a
fracture, could extend even a deflected antero-posterior incomplete
division to any of the borders of the bone.

There are, it seems to me, only three possible ways in which an
oblique suture, extending between any two borders of the parietal
bone, can be produced.

In the first case the oblique suture, or rather a suture-like
formation, may be the effect of an early fracture. A fracture produced
in adult life is generally recognizable as such; but a fracture dating
from earlier stages of life, produced before the growth of the bone
has ceased, may, if not entirely obliterated, present more or less the
characteristics of a suture. I have seen several skulls where a
division in the parietal bone or the temporal squama presented at the
same time features of a fracture and suture; in one or two of these
cases so much so, that it was and still is impossible for me to decide
exactly which of the two conditions I had before me. Gruber describes
one such case[12] as an instance of an oblique parietal suture, while
Hyrtl and Ranke both consider this case as one with an acquired
division. To differentiate a congenital real oblique suture from a
division which is the result of a fracture, we must be guided largely
by the situation, form, and serration of the division, and the
condition of the surrounding bones, especially that of the opposite
parietal. A straight course, ending with one extremity in or near the
middle of the anterior or posterior border of the parietal, a complex
serration, no continuity of the division on the neighboring bones, and
particularly a co-existence of an allied or similar division on the
opposite parietal,--all favor the conclusion that the division under
consideration is a real congenital suture, and not the result of a

In the second case there are reasons for believing that an oblique
suture of the parietal bone can originate in the same way as the
horizontal one, namely, through a persistence of the original separation
between the two centres from which the bone is developed, and a
co-existent difference in the relative position or the relative growth
of the two centres. It is in this connection that the above-described
division in the parietals of the chimpanzee will prove of value.

The occasional persistence of the separation between the two original
segments of the parietal bone is sufficiently demonstrated by the
presence of the complete horizontal parietal suture. Differences in
the relative position of these segments can be observed in a limited
degree in Ranke's illustrations of embryos, before referred to; it can
be deduced from such cases as the two of Hyrtl,[13] in which the
division of the parietal was directed from the upper portion of the
anterior to the lower portion of the posterior border of the bone. The
most pronounced change in the position of these centres may be
witnessed in cases where the parietal bone shows a perfect vertical
instead of a horizontal suture. Such cases have been referred to
before, and I presented at the meeting of the Association of American
Anatomists, in 1899, several such examples, found by me in skulls of
monkeys in Professor Huntington's anatomical collection in the Medical
Department of Columbia University. One of these specimens is shown in
the accompanying illustration (Fig. 5).

A difference in the relative growth of the two centres of the
parietal bone is well shown in the difference of size between the
inferior and superior portions of the parietal in cases of the
complete horizontal suture in the same. In the majority of such cases
on record the superior portion is larger, particularly anteriorly,
than the inferior; so much so, that that condition seems to be the
typical one. The difference in the size of the two portions of the
parietal, and in their relative anterior and posterior height, is most
pronounced in one of Gruber's cases,[14] where the "parietal suture"
begins only 10 mm. above the pterion, and ends 40 mm. above the
asterion. In Dorsey's case[15] the lower portion of the divided
parietal is 12 mm. higher than the upper. The same condition as is
found in Gruber's case, here mentioned, exists in the almost identical
left division of the second case of Putnam, of which I have a
photograph in my hands. A somewhat similar excess of the posterior
over the anterior part of the lower severed portion of the parietal
can also be seen in the illustrations of the cases of Tarin, Lucae,
and Turner (Admiralty Islands skull). In Calori's interesting case[16]
there is a decided excess of the lower portion of the divided parietal
in its posterior portion on the left and in its anterior portion on
the right side.

[Illustration: Fig. 5. _Macacus rhesus_ (Medical Department, Columbia
University), showing a Complete Division of the Right Parietal Bone in
a Vertical Direction.]

In case the upper segment was not vertically above the lower one, but
in a position a little more forward or backward of it; and,
furthermore, if the relative growth of the two segments differed, and
their separation remained permanent,--the separation of any portion of
the parietal bone in almost any form and to almost any extent might
result. Such coincidence of anomalous conditions, although
necessarily rare, cannot, from what we know on the subject in parietal
and other bones, be declared improbable. All cases where oblique
suture on one side co-exists with more or less horizontal suture on
the other side in the parietal bone, as in the second of Putnam's
cases, would of course point directly to a similar origin of the
anomaly on both sides of the cranium. That such cases have not been
more frequently observed is largely due, I think, to the rarity of
bilateral parietal divisions.

A third mode of development of the oblique suture in the parietal bone
suggests itself where the severed portion of the bone is small, and
that is the possible existence of a supernumerary, third centre of
ossification. I am by no means ready to defend this theory, yet there
are cases in which it would afford the easiest explanation. I have a
Peruvian skull at hand, in which there is a bilateral, quite
symmetrical quadrangular separate piece of bone, encroaching on the
mastoid process of the parietal. The surface of the left parietal bone
in this skull measures across its middle in antero-posterior direction
120 mm., in infero-superior direction 130 mm.; similar measures of the
right parietal are respectively 117 and 130 mm. The separate bone on
the left measures across its middle in antero-posterior direction 20
mm., in infero-superior direction 12 to 21 mm.; the same portion on
the right measures respectively 25 and 11 to 15 mm. Both pieces are
joined to the parietal bone by a squamous suture (Fig. 6).

[Illustration: Fig. 6 (99/3550). Quadrilateral Fontanel Bones in a
Peruvian Male Skull, encroaching upon the Mastoid Angle of the

It is apparent that the separate pieces of bone in this case are too
small to be easily taken for representatives of one of the regular
centres of ossification of the parietal bone; but the same pieces are
somewhat too large, and especially too singularly outlined and joined
to the parietal, to be without difficulty diagnosed as simple Wormian
or fontanel bones. One of Ranke's cases,[17] though the separation of
the mastoid angle is oblong instead of quadrangular, as in the
Peruvian skull, seems to me to present a similar difficulty in
properly diagnosing the nature of the severed portion. This group of
cases needs further observation, particularly on the bones of infants
and embryos. I have two monkey skulls at hand which actually show a
multiplicity of the original segments of the parietal. These specimens
will be described in a future publication.

So much as to the _formation_ of the oblique sutures in the parietal.
It should not be forgotten that such sutures can be _simulated_ by
those which divide true Wormian or fontanel bones from the parietal.
The distinction between the real oblique parietal and these
extra-parietal sutures must depend largely on the extent of the
division and form of the separate piece of bone.

We may now return to the skull of our chimpanzee. In considering the
nature of the divisions in the parietal bones of this skull, we can at
once and absolutely discard the idea of the divisions being due to
fractures, or being boundaries of Wormian or fontanel bones, and thus
really extra-parietal in their nature. There is nothing about the
sutures, or the divided pieces, or the neighboring bones, that would
even suggest such an explanation; and in our records on Wormian and
fontanel bones we find no analogies either in man, or apes, or lower
animals, to the conditions here observed. The necessary conclusion
from this can only be that we have before us two examples of real
parietal division.

The division on the left side, had it existed alone, would be readily
acceptable as an instance of the "parietal suture." The anterior
extremity and more than the anterior third of the course of the
division correspond exactly to the same features of a typical,
horizontal "parietal suture;" while the elevation of the posterior
extremity of the division, though unusual, can readily be explained as
due to an excess in growth of the inferior original centre of the
bone, which may, in addition, have been situated slightly posterior to
the upper centre.

The division in the right parietal of the chimpanzee begins at its
anterior end, and runs for the first third of its course in the same
way as that on the left side; its posterior end, however, does not
reach the lambdoid, but turns up and ends in the sagittal border.
Should this formation have existed alone, I should be inclined to
consider it either as the result of an accessory centre of the
parietal, or, possibly, as a persistence of the anterior portion of
the divided superior centre of the bone, the posterior portion of the
same being united with the lower segment of the parietal in the usual
way. With the division of the left parietal in the same skull before
me, everything points to a similar origin of the division on both
sides, and to the right as well as the left division being a true
"parietal suture," deflected less on the left and more on the right
side by a disproportion in growth of the two original, regular
segments of each of the bones.

The disproportion of growth of the two original segments of the
parietal bone will, I believe, be found more common as attention is
directed to this subject. It can be well explained, though there may
at times be other factors present, by a difference in the blood-supply
to the two centres. This of course may occur not only in different
skulls, but also on the two sides of the same cranium.


[Footnote 1: Die überzähligen Hautknochen des menschlichen
Schädeldachs, Abh. d. k. bayer. Akad. d. Wiss., II Cl., XX Bd., II
Abth., pp. 36 et seq., Fig. 17.]

[Footnote 2: _L. c._, p. 41. Among 3000 Bavarian crania, Ranke found
but one with complete and three with incomplete parietal sutures;
basing his conclusion on this observation, he says, "Bei den
Orangutanschädeln ist die Häufigkeit der Scheitelbeinnäthe circa 40
mal grösser als bei dem erwachsenen Menschen."]

[Footnote 3: Since finding the abnormal sutures on this skull, I have
been able to present the same at a meeting of the Association of
American Anatomists (1899) and before the Ethnological Society of New
York City (1900).]

[Footnote 4: Toldt, C., in Maska's Hdb. d. gerichtl. Med., 1882, v.
III, p. 515; the same in his U. d. Entwick. d. Scheitelbeins d.
Menschen, Zeitschr. f. Heilkunde, 1883, v. IV, pp. 83-86.]

[Footnote 5: _L. c._, pp. 324-330.]

[Footnote 6: _L. c._, pp. 327-330, Figs. 29-32.]

[Footnote 7: Gruber, W., Beobacht. a. d. menschl. u. vergl. Anat.,
Berlin, 1879, II Heft, pp. 12-15.]

[Footnote 8: Welcker, H., Untersuch. ü. d. Wachsthum u. Bau d.
menschl. Schädels, Leipzig, 1862, p. 109.]

[Footnote 9: Putnam, F. W., Abnormal Human Skulls from Stone Graves in
Tennessee (Proc. A. A. A. S., XXXII, 1884, p. 391).]

[Footnote 10: _L. c._, p. 309.]

[Footnote 11: Ranke's Fig. 25, p. 318.]

[Footnote 12: Virchow's Archiv, 1870, v. 50, p. 113.]

[Footnote 13: Hyrtl, J., Die doppelten Schläfenlinien d.
Menschenschädel, etc. (Denkschr. d. math. naturw. Classe d. k. Akad.
d. Wiss. zu Wien, 1871, v. XXXII, pp. 39-50).]

[Footnote 14: Gruber, W., Beobacht. a. d. menschl. u. vergl. Anat.,
Berlin, 1879, II Heft, p. 15.]

[Footnote 15: Dorsey, G. A., Chicago Med. Recorder, v. XII, Feb., 1897.]

[Footnote 16: Calori, Luigi, Sut. soprannum. d. Cranio Umano (Mem. d.
Accad. d. Sc. d. Ist. d. Bologna, 1867, pp. 327 et seq., Fig. 4).]

[Footnote 17: _L. c._, p. 303, Fig. 13.]

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Transcriber's Note:

  * Footnotes have been moved to the end of the article.

  * Text enclosed between equal signs was in bold face in the original

*** End of this Doctrine Publishing Corporation Digital Book "A Bilateral Division of the Parietal Bone in a Chimpanzee; with a Special Reference to the Oblique Sutures in the Parietal" ***

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