626 APES xxiv. 2-3 



and the canines are incisiform. The molars carry five cusps, not united 

 by ridges. The cercopithecid type was well established by the Miocene 

 and abundant remains are available of *Mesopithecus, with the molar 

 cusps united to ridges. 



3. The great apes : Pongidae 



The question of the exact degree of affinity between the existing 

 apes and man remains unsettled. There were plenty of fossil apes in 



Fig. 404. Gibbon, Hylobates. (From life.) 



Miocene times and man-like creatures are found in the early Pleisto- 

 cene, but we have no undoubted evidence of human remains from the 

 Pliocene and it is therefore impossible to say whether the human stock 

 was derived from apes after Miocene times or whether it separated 

 much earlier, either from the ancestral catarrhine stock, say, in the 

 Oligocene, or, as a few believe, even earlier still, from some Tarsius- 

 like prosimian. Evidence of definitely man-like creatures that can be 

 placed with certainty in a family Hominidae is found only back to 

 about 1 million years ago, whereas the longest of the above estimates 

 would say that our stock has been distinct and evolving separately for 

 nearly 60 million years, without leaving any remains. Although the 

 view that men have descended from apes is probably the more widely 

 held, we shall first survey the structure of the great apes by treating 

 them as members of a separate family Pongidae. 



The living apes include the gibbon, Hylobates (Fig. 404), and orang- 

 utan, Pongo = Simia (Fig. 405), from east Asia and the chimpanzee, 

 Pan (Fig. 406), and Gorilla (Fig. 407) from Africa. They and related 

 fossil forms are marked off from the cercopithecids by their teeth and 

 methods of locomotion. Many apes are rather large animals and this 

 has made it impossible for them to walk along the branches as monkeys 

 do. They therefore swing by the arms, which are longer than the legs 



