THE EXTERNAL FORM OF ANTHROPOID APES.
In the gorilla, the chimpanzee, and the orang-utan the external form is
subject to essential modifications, according to the age and sex. The
difference between the sexes is most strongly marked in the gorilla,
and these differences are least apparent in the gibbon.
When a young male gorilla is compared with an aged animal of the same
species, we are almost tempted to believe that we have to do with two
entirely different creatures. While the young male still displays an
evident approximation to the human structure, and develops in its
bodily habits the same qualities which generally characterize the
short-tailed apes of the Old World, with the exception of the baboon,
the aged male is otherwise formed. In the latter case the points of
resemblance to the human type are far fewer; the aged animal has become
a gigantic ape, retaining indeed in the structure of his hands and
feet the characteristics of the primates, while the protruding head
is something between the muzzle of the baboon, the bear, and the
boar. Simultaneously with these remarkable alterations of the external
structure there occurs a modification of the skeleton. The skull of an
aged male gorilla becomes more prognathous, and the incisor teeth have
almost attained the length of those of lions and tigers. On the upper
part of the skull, which is rounded in youth, great bony crests are
developed on the crown of the head and on the occiput, and these are
supported by the high, spinous processes of the cervical vertebræ, and
thus supply the starting-point for the powerful muscles of the neck and
jaw. The supra-orbital arches are covered with wrinkled skin, and the
already savage, and indeed revolting, appearance of the old gorilla is
thereby increased. A comparison of the two illustrations (Figs. 1 and
3) which accompany the text, will make this clear.
These distinctions are not so striking in the female as in the male
gorilla. Although there is much which is bestial in the appearance
of an aged female, yet the crests, so strongly marked in the male,
the projecting orbits, and strong muscular pads are absent in the
female, as well as the prognathous form of the skull and the length
and thickness of the canine teeth. The aged female gorilla is not, in
her whole structure, so far removed from the condition of the same sex
in youth as is the aged male. The structure of the female has on the
whole more in common with the human form. It has been said, and indeed
on good authority, that the female type should take the foremost place
in the study of the animal structure, since it is the more universal.
But H. von Nathusius maintains that we must take both sexes into
consideration in the study of domestic animals, since both are needed
to determine the breed.[2] I accept this condition in the scientific
study and description of wild animals also, of every kind and species.
All that is said of the universal type of the female animal is and
must remain in my eyes a mere phrase. Only the accurate observation of
males and females, and of young individuals of both sexes, can throw
sufficient light on the history of the race. The male animal is the
larger, and predominant with respect to the complete development of
certain peculiarities of form in the specific organism, since these
are doubtfully present in the adult female, and are either altogether
absent in the immature young, or only rudimentary.
Let us now consider, in the first place, the prototype of the species,
the aged male gorilla in the full strength of his bodily development
(Fig. 1). This animal, when standing upright, is more than six feet
in height, or 2000 mm. The head is 300 mm. in length. The occiput
appears to be broader below than above, since the upper part slopes
like a gabled roof towards the high, longitudinal crest of the vertex.
The projecting supra-orbital arches start prominently from the upper
and central contour of the skull. In this species, as in other apes,
and indeed among mammals generally, and especially in the case of the
carnivora, ruminants, and multi-ungulates, eyebrows are present.
In the gorilla these consist of a rather scanty growth of coal-black
bristles, about 40 mm. in length. Beneath the projecting supra-orbital
arches are the eyes, opening with somewhat narrow slits, and with lids
which display many and deep longitudinal folds. The upper lid is set
with longer and thicker eyelashes than the lower. The dark eyes glow
between the lids with a ferocious expression.
[Illustration: Fig. 1.--Aged male gorilla.]
The bridge of the nose rises gradually outwards from between the inner
corners of the eyes, and is keel-shaped in the centre. This part of
the head is from 70 to 80 mm. in length, longer and narrower in one
individual, shorter and wider in another. The skin in this region is
covered with a network of wrinkles of varying size. The end of the
nose and the nostrils are high, conical, and very wide at the base.
This part of the nose, attached to the very projecting forehead, has
the effect of an altogether snout-like muzzle. It is intersected by a
central longitudinal furrow, which divides the whole tip of the nose
into two symmetrical halves. This furrow is more strongly marked in the
case of adult animals than in the young. The aperture of the nostrils
is large and triangular, with the cartilaginous point turned upwards,
and the edges applied to the bridge of the nose and to the cheeks
have a somewhat retreating appearance. The lateral margins of this
part of the nostril take an arched form, first diverging in different
directions, then gradually converging again towards the upper lip. The
lip is short, and this, combined with the large nose, gives a certain
resemblance to the mouth of an ox. This resemblance is the more
striking, as the whole of this region is covered with glandular skin of
a deep black colour, which is either glabrous or provided with a few
scattered hairs, but furnished with small flattened warts.
Below the eyes the cheeks are broad and very round, dwindling away and
becoming depressed in the lower part of the face. They are seamed with
curved wrinkles of varying depth, which tend downwards in the same
direction as the wrinkles on the lower eyelids. The short upper lip is
provided with oblique folds which converge outwards in the centre. The
points of the strong canine teeth, which in many individuals are from
38 to 40 mm. long, and 20 mm. wide, diverge a little from each other,
and stretch the upper lip in an oblique direction, so that this part
of the face takes the form of a triangular, bevelled surface, with its
prominent base-line between the canine teeth. It may also be observed
that in many individuals of this species the nose is not very deeply
set on the upper lip; that in others, again, the nose is decidedly
raised, and the lip only presents a small hem below the nose. In many
such cases the prognathism of the face is strongly marked, so as to
give a baboon-like effect. In other specimens, again, this debased type
is not allied with strongly marked prognathism.
If we take a front view of the skull of an aged male gorilla we see
that the upper edges of the great supra-orbital arches are bevelled
off below and at the sides. This bevelled form is repeated in the
broad cheek-bones, as we see them in front. The front view of the
head, and indeed of the whole animal, presents a strongly projecting
contour, an impression which is strengthened by the puffed cheeks, with
their lateral pads of fat. The lower jaw, with its scarcely indicated
chin, retreats in the centre and dwindles into a triangular form. This
contour is characteristic of the species. The whole skin of the face is
glossy, set with few hairs, and of a deep black colour.
[Illustration: Fig. 2.--Ear of a male adult gorilla.]
The ear (Fig. 2) averages 60 mm. in length, and from 36 to 40 mm. in
width. It seems to be fastened to the head by the back and upper part,
is generally of an oval shape, and furnished with a strongly marked
helix. The helix varies in width in different individuals, and often
terminates on its inner edge in the projecting peaked excrescence
described by Darwin, of which I shall have more to say presently. The
anti-helix, tragus, and anti-tragus, and the cleft which lies between
these two latter parts (_incisura inter tragica_) are generally fully
developed; the lobule is more rarely present. Individual variations in
the special structure of these parts may frequently be observed.
The strong trapezoid muscles are prominent on the neck, and when the
head is stretched they stand out like pillars on the sides of the neck.
Owing to the great development of the spinous processes of the cervical
vertebræ and of the muscles attached to them, and to the occipital
bones of the skull, the neck is very powerful, almost like that of a
bull. The shoulders are remarkable for their breadth, and the pectoral
muscles for their large size. The nipples of the breast, which are not
surrounded by any visible _areolæ_, stand out in youth, and afterwards
assume a horny texture which stiffens into a kind of bone. When one of
these animals is gorged with food the navel is still apparent on the
tun-shaped, rounded belly, of which the sides fall in when the stomach
is empty.
On the upper and forearms the plastic form of the strongly developed
flexor and extensor muscles is very apparent, testifying to the
enormous strength of the upper extremities. The hands are large,
and very wide, with short, thick fingers. The thumb, of which the
extremity takes a conical form, is short, extending little beyond the
middle of the second metacarpal bone. The extremities of the otherwise
broad fingers are somewhat laterally compressed. The fore-finger is
not materially shorter than the middle finger. The third finger is
sometimes shorter than, sometimes of the same length as, the first,
and the fourth is decidedly shorter. The back of the wrist is covered
with deep oblique folds. A network of wrinkles, oblique or curved,
also covers the skin on the back of the fingers, on which there are
callosities up to the first joint. The gorilla closes the fingers when
going on all fours, and turns the back of the hand on the ground, thus
producing this thickening of the upper skin on the joints. Callosities
of the same nature, although not so extensive, are not rare on the
second finger-joints. The palm of the hand is covered with a hard,
horny skin, generally beset with warts, especially at the roots of the
fingers. In spite of the blackness of the skin which covers them, these
characteristics are still apparent.
The fingers are united by a strong web, reminding us of the membrane
found on the otter and other web-footed animals, and reaching nearly
to the first finger-joint. A thick coat of hair extends to the root of
the fingers, although on the backs of the fingers there are only a few
isolated hairs.
The trunk of the body of a gorilla, seen from behind, somewhat
resembles a trapezium in form, of which the longer of the two parallel
sides extends between the shoulders, and the shorter between the two
halves of the pelvis. The longitudinal sides, which are not parallel,
correspond to the sides of the back. The arrangement of all the
lower part of the trunk, on which the bones of the pelvis stand out
prominently in an oblique direction, somewhat resembles a four-sided
pyramid with its apex reversed. The gluteal muscles are not strongly
developed. The tuberosity of the ischium projects in a somewhat angular
form.
While the external sexual organs of the male are so covered by the
wrinkled skin of the abdomen that they are not prominent in their
passive condition, those of the female are, on the contrary, very
apparent; the external lips of the vagina, provided with large nymphæ,
and a large clitoris, are only apparent when the sexual instinct is
excited.
The thighs are covered with strong muscles, which appear to be smoothed
off on the inner side, and somewhat arched on the outside. The lower
part of the leg is also muscular, and its section is of a long-oval
form; the region of the calf is more strongly developed than in other
anthropoids. The bones of the foot are not at all prominent, and the
same remark applies to those of the hand. The contour of the back of
the long, broad foot is flat; the sole is convex, covered with strong
muscles, and padded with layers of fat. When the animal puts the sole
of the foot on the ground, its muscles go back to the region of the
heel, and forward into the inner side of the foot, thus presenting the
primitive formation of a heel.
The great toe, as in all apes, is detached like a thumb from the other
toes, and can be used as such. The metatarsus serves as a base for its
projection, in the same manner as the thumb starts from the fore part
of the contour of the wrist. The great toe sometimes extends as far as
the joint between the first and second phalanges of the second toe,
sometimes nearly as far as the middle of the second phalanx. This
characteristic varies in different individuals. At the point of union
of the first metatarsal bone with the hinder extremity of the first
phalanx of the great toe, there is a round projection on the inner side
of the foot. The great toe is very broad at its root, then becomes
smaller, and widens again into a broad final phalanx. With its strong
lateral ridges of skin, which cover the sinews and cushions of fat, all
this part of the foot appears to be wide and flattened off from the
back to the sole.
The second, third, fourth, and fifth toes are more slender than the
great toe. The second toe is in most cases rather shorter than the
third. The third and fourth toes are almost of the same length,
and only a little longer than the second toe.[3] The fifth toe is
considerably shorter than the fourth. The last phalanges of the toes
taper in front, and are furnished on their lower surface with long,
laterally compressed pads. The section of such a phalanx is almost
trapezoidal, with a long upper parallel side. The upper part of the
foot, although generally flat, rises a little in the neighbourhood of
the first metatarsal bone, and slopes thence to its outer edge.
The hair grows thickly on the back of the foot as far as the extremity
of the metatarsal bones, more sparsely on the back of the toes.
There are strongly marked oblique furrows on this part of the foot,
especially on the joints, often combined with horny callosities,
since the animal sometimes doubles up the toes and runs upon the back
of them. The nails of the hands and feet are black, like the whole
of their skin-covering, distinctly grooved, very much arched, and
generally somewhat wider at the base than in front.
[Illustration: Fig. 3.--The young male gorilla, from the specimen in
the Berlin Aquarium of 1876–77.]
On the sole of the foot we find the region of the heel, the ball
of the great toe, in this case resembling the ball of a thumb, the
roots and tips of the toes, together with pads consisting of muscles,
tendons, and skin. The several divisions of these padded balls are
separated from each other by furrows which are longitudinal, oblique,
and transverse, and more or less distinct from each other. The black
skin which covers the sole of the foot is thick and horny, but provided
with a series of papillæ. The whole skin of an aged animal is of a deep
black colour, somewhat glossy, and covered with intersecting wrinkles.
[Illustration: Fig. 4.--The same animal at a still earlier age.]
The young male gorilla does not essentially differ from the old male
in its general and external appearance. Its skull is, however, without
the crest which characterizes the latter animal, and is still of a
rounded form in the region of the crown and occiput. At this age the
head is not so high at the back and on the top as in aged males. The
orbits are less prominent, the general aspect of the face is not so
decidedly prognathous, and the bridge of the nose is shorter. The lines
of the body in the young male are softer and less exaggerated, and the
expression of the face is less ferocious than in an aged male. The
horny callosities on the hands and feet are altogether wanting or only
faintly indicated, and the hands, fingers, and toes have not arrived at
the powerful development which we observe in the older animal. (Comp.
Figs. 3 and 4.)
Considerable differences may be observed in the whole structure of the
adult female gorilla. The animals of this sex are smaller and weaker
than males of the same age. The skull of the female is smaller and
more rounded than that of the male, and the great bony crests are also
absent. The orbits are less prominent, and a front view of the head
gives the impression of a trapezoidal form. The coronal arch rises
above this trapezoid. In the male, on the contrary, the crown seems to
lengthen above and behind into a pyramidal form. In the aged female
the bridge of the nose is generally shorter than in the aged male,
but even in this particular there is great variation in different
individuals. Sometimes the bridge of the nose in a female is much
depressed, and then the interval between the orbits and the end of the
nose is shorter: I intentionally avoid the term _tip_ of the nose, on
account of the blunted form of this organ. Even when the bridge of the
nose is more prominent, the interval between its end and the orbits is
sometimes very short.
The aged female gorilla usually has wider cheeks, a smaller nose, and
a higher upper lip. This last peculiarity is shown in the correct and
well-stuffed specimens in the museums at Paris and Lübeck. Although,
in the process of drying, the skin of the nose may have shrunk a
little, yet there is still room for the upper lip, provided with folds
which are either vertical and parallel or diverge like a fan. Owen and
Mützel[4] have given satisfactory illustrations of these parts. In the
aged female the shape of the neck is not, as in the aged male, strong
and bulging, so as to resemble a cowl. Yet it is enlarged in conformity
with the not inconsiderable development of the spinous processes of
the cervical vertebræ, and with that of the powerful cervical muscles.
Even in a young male, of the age of the specimen which was kept in
the Berlin Aquarium, between July, 1876, and November, 1877, this
enlargement of the neck was present in a marked degree. In still
younger individuals, however, under a year old, in which the spinous
processes of the vertebræ have not yet been developed, there is no such
enlargement, but, on the contrary, this region of the neck takes a
concave form.
In conformity with the smaller size of the body, the shoulders, arms,
and thighs of the adult female are smaller than those of the full-grown
male, but they are still very powerful. While giving suck, the breasts
of the female are swelled in the form of a half-cone, instead of
assuming the convex shape which is observed in many European women,
and still more frequently in those of the negro, Indian, and South
Sea races. The nipple is cylindrical rather than conical in shape, and
covered with finely wrinkled black skin, which is sometimes hard and
horny. When not giving suck, the breasts hang slackly down, like short
empty pouches. The belly swells in the neighbourhood of the crest of
the ilium, and increases in thickness at the groin. The external sexual
organs, in the period of excitement, swell in a manner resembling the
lips of a woman’s pudenda.
In a young female the cranium is rounded, and the face is only slightly
prominent. In aged specimens, especially in those of the male sex,
there is a somewhat typical prolongation of that part of the face which
lies between the eyes and the end of the nose, and this is to a slight
extent apparent in the young female. Variations in form and in the
extent of the prolongation are, however, apparent even at this early
period. The trunk and limbs are more slenderly built than in a male of
the same age.
The hairy coat of the gorilla consists of long, thick, straight or
stiffly curved bristles, and also of shorter, thinner, and curled
woolly hair. On the crown of the head the hair is somewhat stiff,
from 12 to 20 mm. in length, and it becomes erect under the influence
of anger. While the sides and fore-part of the chin are only clothed
with short, stiff hairs, they grow thickly on the back part of the
chin, like a beard or forelock. The hairs which turn outwards from
the sides of the face and on the neck are 30 or more mm. in length.
On the shoulders the hair is from 130 to 150 mm. long, hanging down
on the upper arms and the back. In the middle of the upper arm the
hair is from 50 to 70 mm. long, growing downwards as far as the bend
of the elbow. At this point it generally begins to grow in an upward
direction. On the back of the forearm it again grows downwards. In
the middle of the forearm on its inner side, a parting of the hairs
takes place, as one portion goes in front of the radius, while the
other portion turns behind the ulna. On the back of the wrist a tuft
of curved hair turns upwards; a middle tuft goes directly back; and
the lower tuft, also curved, turns outwards. On the back of the hand
the hairs turn towards the fingers. On the breast and belly the hairs
are shorter and grow more sparsely. On the breast their direction is
as a rule upwards and outwards. On the belly they converge from the
ribs towards the centre and the navel. On the thighs the hairs are
about 160 mm. long, and here, as on the lower part of the leg, they
tend outwards, while on the back of the foot they grow towards the
toes. On the back, shoulders, and on the thigh and leg, the bristles
are slightly curved. This quality increases the general impression of
shagginess and fleeciness which is produced by the hairy coat of these
creatures. The woolly hair does not grow very thick, and is not much
matted.
The colour of the hair not only differs on different parts of the body,
but also in different individuals. On the crown of the head it is of
a reddish brown, or rarely of a decided brown or black. The hairs in
this region are sometimes dun-coloured at the root, greyish white in
the centre, and brownish red, shading into the dark brown tip. The
hair on the lips is sometimes of a blackish brown, sometimes whitish,
or both colours are found together. The hair growing at the sides of
the face is grey below, dark brown or almost black above. On the neck
and shoulders the hair is of a grey colour at the root, and gradually
becomes lighter towards the tip. In the centre it is brown, shading
into a lighter colour at either end, but this ringed form of colour
is not universal. The tips of the hair are dark, sometimes brown or
reddish. The hair on the back, on the upper arms and thighs, is whitish
or light grey for half its length, with a blackish brown ring towards
the tip, which is of a dark grey colour. Many of these hairs on the
back have two brown rings on them. The forearms, hands, shanks, and
feet are covered with hairs which are grey at the root, brownish grey,
dark brown, or black at the tip. Round the posteriors there is a circle
of white, grey, or brownish yellow hairs from 10 to 20 mm. in length.
In both sexes variations from the colour of the coat here described are
not rare. It has been already observed that the brownish red colour
of the hair on the head is sometimes exchanged for another shade. In
many individuals the neck, shoulders, and back are of a dark grey,
brown, or even black colour. In others the forearms, hands, shanks, and
feet are covered, like the rest of the body, with grey and brown hair
intermingled.
The second species of anthropoid apes is the chimpanzee. In this case
also we must consider successively the aged and young male, and the
aged and young female animals.
The full-grown chimpanzee is smaller than the adult gorilla. In this
species also the male is larger than the female. The chimpanzee is,
speaking generally, of a slighter build than the gorilla.
The head of the aged male chimpanzee fundamentally differs from that of
the aged male gorilla, since the skull of the former has a depressed
crown, and the transverse occipital ridge is only faintly indicated.
Since the orbits are also less strongly developed than in the aged male
gorilla, and the spinous processes of the cervical vertebræ do not
assume the same elevated form which is characteristic of the latter
species, the countenance of the chimpanzee is not of a square shape,
and there is not space for the strong muscular system arching over
the neck like a cowl, which is so characteristic of the gorilla. The
head of the chimpanzee displays, both in aged and young specimens, the
concave neck which is common among apes, that is to say, a depression
between the head and the throat. In an aged male the crown of the head
presents a rounded, arched contour, since, as we have already said,
the prominent bony processes are wanting. Although the supra-orbital
arches are not so excessively prominent as in a gorilla of the same
age, they are strongly developed, covered with wrinkled skin, and in
this case also there is a species of eyebrow, stiff and bristly, with
shorter hairs between. The large, wrinkled lids are furnished with
thick eyelashes. The inner angle of the eye somewhat resembles that of
the gorilla.
A general physiognomical distinction between the gorilla and the
chimpanzee consists in the fact that the bridge of the nose is shorter
in the latter than in the former. In the chimpanzee this part of the
organ is depressed, yet the depression is of a conical and convex
form, and is covered with a network of wrinkles of varying depth. In
the chimpanzee the interval between the inner angle of the eye and the
upper lateral contour of the cartilaginous end of the nose is shorter
than in the gorilla. There is also some difference in the form of
the nose: it is on the whole flatter, the tip is less apparent, the
nostrils are not so widely opened nor so thickly padded. (Fig. 3.)
In the chimpanzee, as well as in the gorilla, a central and vertical
furrow directly divides the triangular nostrils, and these are likewise
divided from the rest of the face by the broad pear-shape furrow which
surrounds them. The upper lip is generally high, sometimes as high as
30 mm.; but in some individuals it is much lower. As in the gorilla,
the chin forms a triangle of equal sides, with its apex reversed.
The external ear of the chimpanzee has on the whole less resemblance
to the human ear, and its contour is larger than that of the gorilla.
But this organ varies so much in individuals that it is difficult to
lay down any rule for its average size. It ranges from 59 to 77 mm.
in length, and from 42 to 80 mm. in width. Many individuals have a
distinct lobule to the ear, others not. (Fig. 5.) In this example
the helix and anti-helix are developed, in others they are wanting.
The tragus and anti-tragus are more or less apparent in different
individuals, as well as the other modifications of the external
cartilage of the ear.
[Illustration: Fig. 5.--Ear of chimpanzee.]
An aged male chimpanzee has broad, rather rounded shoulders, a powerful
chest, long muscular arms, reaching to the knees, and a long hand,
which seems to be very slender in comparison with that of the gorilla.
The thumbs vary in length, for the most part reaching as far as the
metacarpal phalanges, but not in all cases. The middle finger is longer
than the other three; the first and third fingers are shorter by the
length of the last phalanx, the third is a little longer than the
first, and the fourth is again shorter. A web, which reaches to the
middle of the first row of phalanges, stretches between the bases of
the four fingers. There are horny callosities on the back of the hand
of the aged male, since the chimpanzee, like the gorilla, supports
himself on the backs of his closed fingers. The fingers are laterally
compressed, but slightly arched on the back of the hand, and more
decidedly so on the palm. A network of furrows covers the back of the
hand, and these are more deeply impressed on its palm. The thumb is
separated from the palm by a distinct furrow; and from four to six
furrows of varying depth cross the centre of the palm. The finger-nails
are short, wide, and arched, very convex at their free edges.
In the aged male the sides of the belly are compressed, the thighs
are broad and muscular, and somewhat flattened both on the inner and
outer sides. The knees are rather prominent, the shanks are somewhat
laterally compressed, and the calf of the leg is very slightly
developed. As in the gorilla, the long, wide feet have a thumb-like
formation of the great toes, which are of considerable size. They
extend, when drawing anything towards them, as far as the second
phalanx of the second toe. The four other toes are more slender and
only a little longer than the great toe. The heel is but slightly
developed, and slopes away below. The joint between the first phalanx
of the great toe and the first metatarsal bone is marked by an angular
projection on the inner edge of the foot. The back of the foot is very
slightly convex. The last phalanx of the great toe is very much sloped
off on its upper surface, but this is less apparent in the other parts
of this member. The last phalanges of the other laterally compressed
toes are strongly arched on the under surface. Considerable convexities
may also be observed under the metacarpo-phalangeal joint of the great
toe and under its last phalanx. The shape of the toe-nails resembles
that of the fingers. Large callosities are not unfrequently found on
the backs of the toes, since the animal sometimes supports himself on
these parts. A connective web is found between all the toes except the
great toe and its neighbour, but it does not extend so far as that
between the roots of the fingers.
[Illustration: Fig. 6.--Young chimpanzee.]
Although the young male chimpanzee is distinguished from the aged
male of the same species by differences in the structure of many
of its parts, yet these distinctions are not so characteristic as
those between the young and aged male gorillas. The skull of the
younger animal, which is altogether devoid of the prominent bony
crest and ridges, is shaped almost like a truncated cone in the
region of the crown; in some individuals of only a few years old, the
bony development of the orbits has already begun, starting from the
principal part of the frontal bone, and covered with pads of wrinkled
skin. The short and depressed bridge of the nose becomes longer and
higher, the cartilaginous end of the nose becomes larger, and the
prognathism of the face increases with each successive stage of growth.
The strength of the trunk and limbs is early developed. The sexual
characteristics are gradually and plainly developed; but the male
gorilla far exceeds the chimpanzee in demoniacal ferocity.
The adult female is smaller, and has a smaller head, with an oval crown
to the skull. The orbits are not so strongly developed as in the aged
male, the nasal parts are less prominent, and the teeth are not nearly
so strong. The body of an animal of this sex is rounder in all its
parts; and the belly, with its wider pelvis, is more tun-shaped than in
the aged male. Neither do the limbs display the same angular formation
of muscles.[5] The hands and feet of the female are also smaller and
slenderer. In a young female the characteristics here described are
presented in the mitigated form which corresponds with its youthful
condition. But the female sometimes becomes a very strong and even
violent creature. This was often proved in the Hamburg Zoological
Garden, where a female specimen, in splendid condition, survived for
several years under the faithful care of old Siegel.[6]
The skin of the chimpanzee is of a peculiar light, yet muddy flesh
colour, which sometimes verges upon brown. Spots, varying in size and
depth of colour, sometimes isolated, sometimes in groups, and of a
blackish brown, sooty, or bluish black tint, are found on different
parts of the body of many individuals, especially on the face, neck,
breast, belly, arms and hands, thighs and shanks; more rarely on the
back. The face, which is soon after birth of a flesh colour, merging
into a yellowish brown, assumes a darker shade with the gradual
development of the body. The hairy coat is sleek, or only in rare cases
slightly curled, and the coarser and bristly hair is generally stiff
and elastic. The parting on the forehead is often so regular that it
might have been arranged by the hairdresser’s art (see Fig. 6). Close
behind that part of the head at which the projecting supra-orbital
ridges of the gorilla generally meet, there is in the chimpanzee an
altogether bald place, or only a few scattered hairs. Round the face
the growth of hair streams downwards like a beard. On the neck it is
from 60 to 80 or 100 mm. in length, and it falls in the same long locks
over the shoulders, back, and hips. The hair on the limbs is not so
long, and takes a downward direction on the upper arm, and an opposite
direction on the forearm, while there is often a longitudinal parting
on the centre of the inner surface of this part of the limb. On the
back of the wrist the hair grows in a kind of whorl; the upper hairs
turn upwards and backwards, the middle ones turn backwards, the lower
ones backwards and downwards. The backs of the hands and the roots
of the fingers are hairy. On the front of the thigh the hair takes
a downward direction, while behind it grows backwards. On the shank
it grows downwards in the region of the tibia, and turns back on the
inside of the leg. The back of the foot and the roots of the toes are
likewise hairy. There is a shorter growth of these scattered hairs on
the face, chin, and ears. On the supra-orbital arches there are from
eight to twenty, or even more, stiff, scattered hairs, after the manner
of eyebrows; and eyelashes are likewise present.
In most cases the hair of the true chimpanzee is of a black colour.
Short whitish hairs may be observed on the lower part of the face and
chin, as well as round the posteriors. Sometimes the colour of the hair
is shot throughout with reddish or brownish black.
The orang-utan, the chief representative of the anthropoids in
Asia, differs from the African forms of this group, almost at the
first glance, in the height of his skull, of which the fore-part is
compressed and shortened in a backward direction. In the aged male it
is, however, provided with high and erect bony crests, which give a
prognathous appearance to the countenance. We take an aged male as the
type of our description.
The forehead is high and erect, not retreating like that of the
chimpanzee; it is open, and has moderately convex frontal eminences.
From the centre of the forehead a round or bluntly oval eminence
sometimes projects. The supra-orbital ridges are strongly arched,
yet not so prominent as that of the aged male chimpanzee, setting
aside that of the gorilla. The eyes are not widely opened, nor are
their lids large and furrowed, but on the lower lids there are deep
wrinkles. The small bridge of the nose is generally much depressed, but
sometimes assumes a slightly conical form as it issues from the central
longitudinal depression of the face. The end of the nose, further
removed from the eyes than is generally the case in the chimpanzee,
is not so broad as it is in the latter animal and in the gorilla. The
wings of the nose are narrow and highly arched in their upper part,
divided from each other by a vertical furrow, and the nostrils are
small and oval, separated by a thin partition. The upper lip is high,
broad, and projecting, and seldom much wrinkled. It is divided from the
cheeks and from the upper part of the face by a deep depression; and
behind the cheeks two large and long-shaped or sometimes triangular
pads of fat often project forwards and downwards.
[Illustration: Fig. 7.--Head and shoulders of an aged male orang-utan.]
The very mobile lips are furrowed, and not remarkably thick. The chin
is very retreating, but somewhat uniformly rounded in front (Fig. 7).
The small ear averages 55 mm. in length, and 12 mm. in width, and has
a general resemblance in structure to the human ear (Fig. 8). On the
fore-part of the short, thick neck there are irregular, and in some
places very deep circular folds of skin. The throat-pouch distends part
of this slack, wrinkled skin, which hangs down in front like a great
empty wallet (see Figs. 7 and 9).
[Illustration: Fig. 8.--Ear of the orang-utan.]
The structure of the other parts of the body lacks even to some extent
the powerful and symmetrical formation which we observe in the gorilla,
and indeed in the chimpanzee. The trunk, with broad yet rather angular
and sloping shoulders, with flattened breast, rounded back, and still
more rounded belly, is tun-shaped, and gives the impression of a
want of proportion. In lean individuals the gluteal region resembles
the projecting rump of a fowl, and this may also be observed in the
young gorilla and chimpanzee. The long, muscular arms reach to the
ankles when the animal is in an erect position, and are altogether
out of proportion with the rest of the body. The powerful upper arm
is shorter than the lean forearm. The hand is long and narrow. The
thumb, which reaches as far as the metacarpo-phalangeal joint, has a
displeasing and almost rudimentary effect. A web unites the fingers,
sometimes extending along a third of the first phalanx, sometimes along
half. The middle finger is somewhat longer than the first and third
fingers, and the third is next to it in length. The fourth finger is
comparatively long. The palm of the hand is flat, only marked by a few
deep furrows. The long, slender fingers are laterally compressed, and
the nails on their tapering ends are arched.
[Illustration: Fig. 9.--Adult male orang-utan.]
The thighs, somewhat compressed on the inner side, are, however, very
muscular, but become much smaller on their back side. The calf of
the leg is less developed than in the gorilla, or even than in the
chimpanzee. The feet are, like the hands, long and slender. The narrow,
flat heels project very slightly behind. The great toes are short, with
wide extremities, rounded above, and provided on the sole with thick,
fatty skin. In old age these animals not only often lose the nails of
their great toes, but sometimes even the last phalanges themselves.
This is not merely a disease produced by confinement, as is the case
with sea-cat monkeys, hyenas, etc., which in this condition lose
portions of their tails or toes, but it also occurs among orang-utans
in their wild state. The middle toe is the longest, and the fourth toe
is the shortest. Layers of fat may be observed on the under side of all
but the great toe, where they rarely occur. The backs of the hands and
feet are covered with very ribbed and wrinkled skin, and on the hands
there are callosities.
This animal, of a quieter and more phlegmatic disposition than the
gorilla and chimpanzee, has a very strange appearance, with its
projecting head and short neck; its face widening in the middle
and tapering towards the forehead and chin; its tun-shaped trunk,
long, thin extremities, and shaggy coat. It differs widely from the
chimpanzee and gorilla in these particulars. In the young male the
compression of the forehead is less marked than in aged animals, and
the bony crests which conduce to raise the coronal arch in its upper
and hinder part are also absent. The supra-orbital arches are less
strongly developed, the jaws are less prominent, and the layers of fat
upon the cheeks are absent. The head is more detached from the neck,
the structure of the whole body is slenderer, the expression of the
countenance is milder. A small, conical nail, blunted at the end, may
generally be observed on the great toe.
In the adult female, as I have pointed out elsewhere, the physical
characteristics of the young male are repeated in an exaggerated form.
The skull, displaying only very small bony crests, is indeed high, but
more rounded than in the aged male; the face is prominent, but the head
is more detached from the neck than in the latter case. On account of
the greater width of the pelvis, the body is still more tun-shaped than
in the aged male. When giving suck, the breasts are distended in the
form of a half cone, but when this condition ceases they fall together
and only present two short, wrinkled, slightly prominent folds of skin;
the small, horny nipples are almost cylindrical; and the areola, of
which the traces are scanty at all times, altogether disappears. The
throat-pouch is less strongly developed than in the aged male, but the
limbs are as fully developed. The head of the young female is still
more rounded, with a more flattened though still projecting face, and
the limbs are slenderer, and thus still more out of proportion with
the thick trunk than is the case with a young male.
The orang-utan’s skin is of a greyish blue colour, sometimes mixed
with brown, but the greyish blue shade is predominant. A yellowish or
brownish grey is less common. Round the eyes, nostrils, upper lips, and
chin there is often a ring of a dirty, yellowish brown colour, forming
a strange contrast with the general bluish grey tone of the face. The
arms, legs, hands, and feet are black or greyish black, more rarely
brown or reddish brown.
The hairy coat of the orang-utan consists of long, curved, waving
bristles, and some scanty downy hairs. On the back of the head, on the
shoulders, back, and hips I have measured hairs from 220 to 235 mm.
in length. In other individuals they were, however, much shorter--20,
40, or 60 mm. long. There is often a natural parting of the hair of
the head, which falls asunder on either side. In some cases there is
no parting, and the hair streams wildly down; and in others, again,
it stands upright, stiffening from the sides and top of the head in a
demoniacal manner (Figs. 7 and 9). A beard frequently encircles the
cheeks and chin. The hair grows upwards and outwards on the neck and
fore-part of the throat, on the shoulders, back, breast, belly, upper
arms, and thighs, while it takes the opposite direction on the forearm.
On the wrist the hair grows in the manner described in the case of the
gorilla. There is only a scanty growth of hair on the breast and belly,
and it is also short and weak on the face, ears, and backs of the hands
and feet. I have not observed eyebrows on the animals I have seen, but
they may occur, and the eyelashes are fully developed.
The hair is of a reddish brown colour, something like burnt sienna,
and the hair-tips on the back parts of the body are generally brown.
In some individuals the hair is darker, of a russet or blackish brown;
in others it is lighter, and in the latter case the breast and belly
are of a yellowish white. The beard is sometimes dark yellow. Some
individuals almost devoid of hair have been observed.
The gibbons, or long-armed apes (_Hylobates_), constitute the fourth
group of anthropoids. Many kinds of this group are known, and I feel
bound to describe, at any rate, a few of them, in order to be able
to give an idea of their structure. With respect to these animals, I
cannot only rely on the materials which are accessible to me, but must
also make use of the descriptions given by others.[7]
The gibbons have as a rule very long arms, reaching to their ankles
when they stand upright. The face is not very prognathous, the crown
of the head is rounded off, and the nails are flat. There are small
callosities on their posteriors, which are absent in the gorilla, the
chimpanzee, and the orang-utan.
The largest species of these animals, which inhabit part of the
continent and of the islands of Asia, is the siamang (_Hylobates
syndactylus_, F. Cuvier).[8] According to Diard, its arms are not
quite so long as those of the wauwau (_H. agilis_, F. Cuvier). This
animal’s head is small, with a somewhat retreating forehead, a long,
moderately arched crown to the head, and a slightly arched occiput. The
base of the nose is depressed, the region of the jaws is only slightly
prognathous in the aged male. According to Diard, the eyes are deeply
set, the nostrils are very wide, the cheeks fall in below the zygomatic
arch, the mouth opens widely, the chin is of insignificant size. It is
the only one of the gibbons which possesses the throat-pouch, already
described as common to the other forms of anthropoids, and in aged
animals it hangs slackly down, almost bare in front. The second and
third toes are connected together by a thin web, reaching to the last
joint in the male, and to the penultimate joint in the female. The
hairs on the forearm turn their points upward, and form a kind of whorl
on the wrist. The animal is of a glossy black colour, with a thick and
tolerably long coat of hair on the body and limbs. According to Bock,
the face is encircled by a grey or white beard. This animal is about a
metre in height, and inhabits the woods of Sumatra.
The lar (_Hylobates Lar_, Illig) is another species of gibbon. The
structure of the body is much more slender than that of the animal
just described; the head is round, the eyes are large, the nose
projects from its depressed surroundings with only a very slight ridge,
and the cartilaginous end is shaped like a triangle with unequal
sides. This triangular end is divided by a longitudinal furrow, and
the small nostrils converge downwards and inwards, and are divided
from each other by a thin partition. The structure of the upper lip is
peculiar. In the centre, just below the base of the nasal partition,
it is depressed, and divided into two symmetrical lateral halves by a
vertical furrow. Each of these halves forms a rounded edge, overhanging
the small lower lip. Above the upper lips, between them and the
zygomatic arch, which slopes away below the lower eyelids, there are
the flat, depressed cheeks. The small chin presents itself below the
central cleft of the upper lips and their convex rims. The face of this
gibbon, of which the general appearance is very singular, is surrounded
by a circle of thick hair, which resembles the circular hood of an
Eskimo. This characteristic form of the head, both generally and in
detail, is not confined to the lar, but applies to other species of
gibbons, including the siamang (see Figs. 11 and 15). It is a feature
which distinguishes the long-armed apes, almost at the first glance,
from the other forms of anthropoids already described. The colour of
the lar’s face is reddish brown or tawny; the hair which surrounds it
is of a light grey: the body is of a dark grey, with short, light grey
hair on the backs of the hands and feet. The black ears are almost
hairless. The lar has up to this time seldom found a place in our
zoological collections. It is found in Malacca and Siam.
[Illustration: Fig. 10.--Head of the white-handed gibbon.]
The white-handed gibbon (_Hylobates albimanus_, Vigors and Horsfield)
is often confounded with _H. Lar_. But _H. albimanus_ has a black face,
and the general colour of the skin is black, including the inside of
the hands and feet. Thick white hair encircles the face, and the backs
of the hands and feet are covered with short white or light grey hairs,
while the rest of the coat is quite black. The hair of the forearm
grows downwards, towards the wrist. The ears of these apes are almost
of the shape of an equilateral triangle. The helix of the ear runs like
a flap round its free outer edge. The anti-helix passes through the
centre of the slightly depressed external surface of the ear, of which
the whole arrangement does not essentially differ from that of the ear
of other anthropoids. The cartilaginous substance of the organ is a
good deal inflected, broad behind and in the upper part, dividing into
two limbs in front and below. There are indications of the tragus and
anti-tragus. The detached lobule of the ear is absent (Fig. 11). This
structure of the external ear is common to other species of gibbons,
although in many cases the upper part of the helix is wrinkled, and the
anti-helix is sometimes more fully developed, and more like that of the
human ear.
[Illustration: Fig. 11.--Ear of the white-handed gibbon.]
The face in this species is small. The supra-orbital arches are
strongly developed, and almost join in the centre. The eyes are large,
dark, and have a mild and placid expression. The cheeks are prominent
in the region of the zygomatic arch, and depressed below it. The bridge
of the nose is imbedded between the cheeks, which, especially when
seen in profile, take a slightly conical form. The nose is covered
with cross-folds. Its cartilage is of the shape described in the
former species, and so are the upper lip and chin (Fig. 10). Long,
bristly hairs stand out on the supra-orbital arches and upper lip, and
short, thin hairs cover the end of the nose. The white hairs which
encircle the face grow like a beard on the chin. The whole face has a
melancholy, almost tearful expression. The neck is short, the trunk
drawn out. On the long, narrow hand there is a short thumb, laterally
compressed, which does not quite reach to the metacarpo-phalangeal
joint. The ball of the last phalanx forms a thick, rounded pad, which
is repeated in a lesser degree on the under side of the first phalanx
of the thumb, and on its ball. The thumb-nail is bent back, as unlike a
claw as the flattened, long, and narrow nails of the other fingers. The
middle finger is only a little longer than the first, and the fourth
not much shorter than the third finger (Fig. 12).
[Illustration: Fig. 12.--Left hand of _Hylobates albimanus_.]
The foot is neatly made, short and narrow, without a projecting heel.
The great toe is very long, reaching almost to the last phalanx of the
second toe. The sole of the foot, and the under side of the great toe,
especially its last joint, are provided with thick, rounded pads. The
middle toe is not much longer than the second, the fourth is shorter
again, and the fifth is only half as long as the fourth. There is only
a very short web between the roots of the fingers, but it extends much
further on the toes (Fig. 13). This species of ape is found in Further
India.
[Illustration: Fig. 13.--Left foot of the same animal.]
The wauwau (_Hylobates agilis_, F. Cuvier, Fig. 14), an ape of a rare
species, may, according to Duvaucel, be recognized by his prominent
supra-orbital arches, sunken eyes, a moderately flat nose, and large
nostrils with lateral openings. The face of the male is hairless, and
of a bluish black; that of the female is brown. The face is encircled
by thick, whitish hair, through which the ears are only partly visible.
There are a few black hairs on the chin. In the male the head, belly,
inner surface of the arms and of the thighs are dark brown. The neck
and shoulders are of a lighter shade, and the hair on the heels is dun
or whitish. The backs of the hands and feet are dark brown. The sides
of the posteriors and the backs of the thighs are brown, chestnut,
or white. In the female the white hair which encircles the face is
shorter, and verges on dun colour. The young animals are light yellow
or brown. This animal inhabits the island of Sumatra.
[Illustration: Fig. 14.--A wauwau in the left foreground (_Hylobates
agilis_); in the background to the light, two slender apes
(_Semnopithecas entellus_).]
The grey gibbon (_Hylobates leuciscus_, Kuhl) is covered with a thick,
long, and woolly coat, with scattered hairs which are curly, and have
two or three rings of dark colour on a light ground. The upper part
of the head is black; light, or sometimes white, hair encircles the
blackish face. The general colour is dun. The front of the throat, the
breast, and belly are of a lighter shade; while the back of the neck,
the shoulders, upper arms, and thighs are darker. A brown or black
stripe runs down the breast and belly from the armpits. The insides of
the hands and feet are black. The colour of young specimens is more
uniformly grey or dun. This animal is found in Java and Sumatra.
The hulock, otherwise called yulock or yoluck (_Hylobates Hoolock_,
Harlan), has, in its adult condition, a prognathous face with prominent
supra-orbital arches, a long, low bridge to its nose, with high, narrow
nostrils, and a very small upper lip. In aged animals there are two
oblique folds over the eyes, of a light grey colour. The rest of the
hairy coat, the face, hands, and feet are black, or, in the younger
animals, brownish black, with grey extremities. A line of grey extends
from the breast downwards over the belly. This animal inhabits the
mountainous district of Assam.
The unko (_Hylobates Rafflesii_, Is. Geoff. Saint-Hilaire) is of a
black colour, shading into reddish brown on the back and sides. Hair,
of a grey colour in the male and white in the female, encircles the
face. This ape is a native of Sumatra.
The dun-coloured gibbon (_Hylobates entelloides_, Is. Geoff.
Saint-Hilaire) is so called from its coat, which is thick and woolly,
and furnished with long hairs of a greyish yellow or dun colour.
This coat is somewhat darker on the inner surface of the arms and on
the neck, where it shades into reddish yellow. The growth of hair
surrounding the face is lighter, verging upon white. The female is
generally more yellow in colour than the male, and the hair on her face
is of a reddish yellow rather than white, but not without a trace of
white hairs. The face and the bare places on the hands and feet are
black. Between the second and third toes there is a connective web
reaching as far as the first joints. This animal inhabits the Malacca
peninsula. The name of the species is derived from its assumed likeness
to the Indian hanuman (_Semnopithecus Entellus_, F. Cuvier), of which
an illustration is given in the background to the right of Fig. 14.
The white-bearded gibbon (_Hylobates leucogenys_, Ogilby[9]) is
remarkable for the long, erect hairs which grow on the upper and back
part of the scalp, and for the long white beard on the cheeks and chin,
which joins the thick growth above the eyes. The rest of the body is
dark black. Its native place is doubtful.
The general colour of the tufted gibbon (_Hylobates pileatus_, J. E.
Gray) is black, shading into grey on the shoulders, back, and thighs.
A white ring surrounds the hands, feet, face, and scalp; and there
is also a patch of white on the sexual organs, and often a patch of
black on the breast. The whiskers are black. In other respects the
animal varies according to its sex and age. It is found in Siam and
Kambodja.[10]
The dark grey gibbon (_Hylobates funereus_, Is. Geoff. Saint-Hilaire)
is of an ashen grey colour on the upper and outer side of its limbs,
verging into brown; and on the under side it is dark brown. There is a
narrow strip of light grey round the face, with a darker band round the
back of the head. It is found in the island of Sulu.[11]
In addition to these species of gibbons of which we have given a
brief account, there are several others--as, for example, _Hylobates
concolor_ (Harlan), from Borneo; _H. Muelleri_ (L. Martin), from the
same place; _H. choromandus_ (Ogilby), from India, and many others. But
since our space is limited, the description given above must suffice
for a diagnosis of the species.