ANTHROPOIDEA 701 
some of the Cebidw they are decidedly compressed laterally, while 
in the Hapalide they assume the form of sharp and curved claws. 
All the Apes have the greater part of the body well clothed 
with hair. In the Gibbons and the Cercopithecide the buttocks have 
naked ischiatic callosities, which attain their greatest development 
in Cynocephalus and its allies. The male of the Orang has a well- 
developed beard, and in Cercopithecus diane there is long hair on the 
cheeks and chin, while in Macacus silenus the face is surrounded by 
a fringe of long hair, separated by an interval on the forehead. 
Long hair is found on the head in Hapale wdipus and in some species 
of Semnopithecus; while in the Bonnet Monkey (Afucacus sinicus) it 
radiates in all directions from a central point on the vertex. Long 
hair clothes the shoulders in Cynocephalus humadryas and Hapale 
humeralifer; and the end of the tail has a tuft in two species of 
Cynocephalus and in Afacacus sinicus. Many of the African Colobdi 
and some species of the Howlers have very long hair on the flanks ; 
and in Pithecta this development of hair extends to the greater part 
of the body and the tail, P. safanas also having a long beard. In 
all the lower Apes the hairs on the arm and fore-arm are directed 
towards the hand quite down to the wrist ; and the same arrange- 
ment obtains in Hylobates. In the other Simiide, however (as in 
man), the points of the hairs of the arm and fore-arm converge 
at the elbow. Darwin’s explanation of this peculiarity is that these 
Apes are accustomed to sit with the arms bent, so that the rain is 
thus enabled to run off at the elbow. 
In one species of Hapale the hair is of a silky texture, and in 
the South American Lrivdes and Afacacus tibefanus (as in all the 
mammals inhabiting the arid and severe climate of Tibet) it becomes 
woolly. 
The development of very brilliant colours on the naked parts of 
the body, such as the face, sexual organs, and ischiatic callosities is 
a marked feature of many of the Cercopithecid and some other Apes. 
With the exception of the long tail found in most forms, the 
general structure of the skeleton of the Apes is very similar to 
that of man, but there are marked differences in the form of the 
jaws and of the innominate bones. The proportion of the facial to 
the cranial region of the skull varies with the shape of the head, 
of which brief mention has already been made; the greatest 
development of the facial portion being in the Baboons. Curiously 
enough, some of the lower American Monkeys, and more especially 
Chrysothrix, have the greatest relative development of the cranial 
part of the skull of all the Apes; this character being, however, 
one common to all the smaller representatives of particular groups, 
and obviously necessary to provide the requisite amount of brain- 
space. In the convexity of the frontal region of the skull the 
American: forms, and more especially Pithecia, make the nearest 
