With the following account of the numerous species of the genera of this
family, we come to consider the first section of the Old World, or
Catarrhine[14] Monkeys. These are {249}distinguished from their New World
cousins, described in the previous pages, by many important and obvious
characters. The partition dividing the nostrils is narrow, instead of
broad, and the openings of the nostrils themselves are directed downwards
and outwards. Certain genera possess also sacs formed by distensible folds
of the skin in the cheeks. These "cheek-pouches" serve as a storing-place
by the side of the jaws, for food which they cannot masticate at the
moment. When this store is disposed of, the folds of skin come together
again and give no indication of the presence of the pouch, which, moreover,
when full does not interfere with the mastication of other food in the
mouth, or with the utterance of the animal's usual cries.
The hind-limbs are never shorter than the fore-; they may be equal in
length, but they are generally somewhat longer, the animal being more or
less quadrupedal, or very partially erect in gait. Their thumb is not
invariably present, but when it is, it is always opposable to its fellow
digits. The great-toe is never rudimentary, and is never, as it is in Man,
the longest, but is the shortest digit of the foot, and it is capable of
free motion to and from the others. All of the digits possess nails. The
length of the foot among this group approximates more to the proportions of
the foot in Man. The hairs on the arms and fore-arms are directed downwards
from the shoulder to the wrist.
The tail in this family varies very much; it may be long or short, or even
externally absent, but it is never prehensile. All the species, however,
possess "callosities," or hard fleshy pads--often of large size--on the
buttocks or seat, which, like the naked skin of the face, are usually
brilliantly coloured and often of large size. The perineal region and
organs are at certain periods, especially in the females, subject to great
turgescence and brilliant coloration.
{250}Besides these external characters, we find, on examining their bony
structure, much variation in the skull. Some have a rounded forehead, the
ascending portion of the lower jaw being high, broad, and flat, with a
large facial angle; in others, we have great production of the upper jaw
(the horizontal part of the lower jaw being greater than the ascending
portion), and a low facial angle. The cerebral portion of the skull is long
and flattened, and the palate long and narrow. The dental formula is I2/2,
C1/1, P2/2, M3/3 = 32, that of the milk-teeth I2/2, C1/1, M (the
forerunners of the permanent _pre-molars_) 2/2 = 20, exactly the same as in
a Man. The outer lower incisors are equal to, or sometimes smaller than,
the inner pair. The permanent canines--which are long and sharp--come in
before, or with the posterior molars of both jaws. Between them and the
incisors above, and between the canine and the anterior pre-molar below,
occurs a gap (or diastema). The anterior upper pre-molar has its outer cusp
modified and sharpened; the anterior lower pre-molar has the anterior
margin of its crown so shaped as to work "as a scissors'-blade against the
posterior edge of the upper canines." (_Henley._) The crowns of the molar
teeth are long from before backwards, and their fore and hind cusps are
united by transverse ridges, a third being present in the same genera, on
the posterior lower five-cusped molar.
The nasal bones are often ossified together to form one bone. The surface
of the skull is in general oval and smooth, but in some of the Baboons
there appear strong ridges over the eyes (hiding the forehead) and along
the top of the head, being stronger, when present, in the male than in the
female. The external orifice to the ear has a considerable bony tube, or
meatus, a distinguishing character which is absent in the New {251}World
Monkeys; their tympanic (or ear) cavity being close to the outer wall of
the skull. The line of junction (or suture) between the upper jaw-bones,
the pre-maxillary and the maxillary, remains unclosed until long after the
permanent teeth have come in. Sometimes it remains unclosed throughout
life. The foramen for the passage of the spinal-cord, and the condyles for
the articulation of the skull with the neck, lie far back.
In the spinal column there are nineteen dorsal and lumbar vertebræ
together. The number of caudal vertebræ varies greatly; in some there are
as many as thirty-one, in others only three. The posterior ends of the
ischiatic bones of the pelvis are rough, flattened, and broad, for the
attachment of the fleshy callosities mentioned above.
The bones of the thigh and leg (_femur_ and _tibia_) together, are longer
than those of the arm and fore-arm (_humerus_ and _radius_) together. The
bones of the thumb are modified more for support and progression than for
the actions of a true hand; by these modifications the movements of
rotation (pronation and supination) are much restricted.
The ankle (_tarsus_) does not exceed one third of the length of the foot.
The stomach is simple, or but very slightly sacculated, in those genera
which possess cheek-pouches; but is tripartite--the middle compartment
being sacculated--in those that have not store-pockets in their mouths, "a
groove with raised edges leading from the gullet-entrance to this middle
compartment." The intestine has a cæcum, or blind diverticulum. "When
laryngeal air-sacs are developed, they are formed by a single sac, with a
median aperture--immediately beneath the epiglottis. This median air-sac is
very large, extending down {252}over the front of the neck, and sending [in
some genera] processes into the _axillæ_" or arm-pits. (_Huxley._)
The main brain (or cerebrum) covers the cerebellum in all the members of
the _Cercopithecidæ_; and in them the principal convolutions and fissures
found in the human brain are more or less developed.
The family _Cercopithecidæ_ includes all the Old World Monkeys except the
Anthropoid or true Apes, and Man, these latter constituting the two
remaining families of the _Anthropoidea_, namely _Simiidæ_ and _Hominidæ_.
The _Cercopithecidæ_ have been again divided into two Sub-families, the
_Cercopithecinæ_ and the _Semnopithecinæ_. The first contains the Baboons
(_Cynocephalus_), the Gelada Baboons (_Theropithecus_), the Mangabeys
(_Cercocebus_) and the Guenons (_Cercopithecus_), all of which inhabit the
African continent; and likewise the Black Apes (_Cynopithecus_) from
Celebes, and the Macaques (_Macacus_), which are almost exclusively
confined to the Asiatic continent. In the second Sub-family are included
the Nosed-Monkeys (_Nasalis_) of Borneo; the Langurs (_Semnopithecus_) of
India, Malaizia, and the Sunda Islands; and the Guerezas (_Colobus_) of
Africa.