76 
NATURAL HISTORY. 
temper is short enough sometimes, especially if there is any disappointment, but they have none of th^ 
mischievous tricks or malice of the Monkeys. Liking milk occasionally, they still mainly feed on 
fruit and leaves, and hence the nature of their teeth, the size of their jaws, and the capacity of their 
brain case may be fairly anticipated. 
The bulk of the brain is less in comparison with that of the Orang, and the hind part does- 
not quite cover or overlap the cerebellum, and the whole skull is long and low, and slightly broad 
behind. The most striking parts about it are the cavities for the eyes (the orbits), which are nearly 
circular in outline, deep, open, and swollen behind ; moreover, they are wide apart, and there 
is no brow ridge connecting them. They, the face and the lower jaw, occupy only one-half of 
the skull, and the brain case is composed of the usual bones, which 
are extremely faintly ridged, the ridges extending on either side from 
the outer part of the orbit on to the frontal and parietal (or side 
head) bones. The back of the skull is rough, for the attachment of 
muscles, and the opening for the spinal cord and the joints for the top 
of the neck are far back, so that the head is set, as it were, forward 
in respect of the spine. There is a long and narrow roof to the 
mouth, and the diastema, or space in the line of the teeth, in front of 
the upper eye or canine teeth, is very distinct. These teeth are 
long, thin, and grooved, and project rather outwards as well as far 
below the other upper teeth. Yet, in all probability, this is not a 
bloodthirsty sign, but one which may have to do with sex, the males 
of many of the Monkeys possessing these great teeth only, or having 
them larger than the females. The first, or incisor teeth, occupy a 
very small space, and they and the two front molars are like those of 
man. An examination of the three true crushing molars shows the 
last, or that nearest the back of the jaw, to be the largest. They 
have four cusps or projections, which are small but decided, and 
somewhat resemble those of insect-eating animals. 
The lower jaw is very remarkable, for it has a good straight chin ; 
and the joint and the part which passes from it to the body of the 
jaw, or the “ angle,” resembles that of man more than that of the 
rest of the Apes. 
The lower teeth are very unlike the upper, and the canines are 
smaller ; the first false molar is pyramidal, and has a cutting surface 
in front and behind. The true molars have at least five cusps or 
projections, and are admirably suited for the creature’s diet. 
One of the most curious points about the Siamang is that the- 
broad breast-bone, the blade-bone, and large chest, and the ribs; 
present human resemblances, but there are fourteen pairs of these last. The hip-bones are long and 
do not curve far in front, but the joint of the thigh is situated more after the manner of that of man 
than is the case in the other great Apes. 
Everything in this creature’s anatomy, and, amongst other things, its delicate, long bones, great 
grasp, supple back, small head, long neck, and long hair, assist in its peculiar life, which is evidently 
one of much climbing, swaying, swinging, and passing from tree to tree with the hands rather than 
with the feet. It lives in Sumatra and in the Malay peninsula. 
SKELETON OF THE SIAMANG. 
( From the ** Cyclopedia of Anatomy and 
Physiology.”) 
THE TRUE GIBBONS. 
The other kinds of Hylobates are called the Tine Gibbons, and although in their habits they 
greatly resemble the Siamang, they are smaller in size, and have some very remarkable structural 
differences. They inhabit the mainland of India and the great islands of Borneo and Sumatra, or. 
rather, all the great islands of the Indo-Malayan sub-region, except the Philippines. They are found 
in Sylhet and Assam, and Camboja, in South China, to the west of Canton, and in the island of 
Hainan. 
