ANTHROPOIDEA 701 



some of the Cebidce they are decidedly compressed laterally, while 

 in the HapaUda 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 Cercopithecidce 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 diana 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 cedipus and in some species 

 of Semnopithecus ; while in the Bonnet Monkey (Macacus sinicus) it 

 radiates in all directions from a central point on the vertex. Long 

 hair clothes the shoulders in Cynocephalus Juimadryas and Hapale 

 humeralifer; and the end of the tail has a tuft in two species of 

 Cynocephalus and in Macacus sinicus. Many of the African Colobi 

 and some species of the Howlers have very long hair on the flanks ; 

 and in PitJiecia this development of hair extends to the greater part 

 of the body and the tail, P. satanas 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 Simiidce, 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 Eriodes and Macacus tibetanus (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 Cercopithecidce 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 



