ANTHROPOIDEA 705 



The Cebidce have a distinct suprascapular notch which is often 

 converted by a bar of bone into a foramen ; this bar in Mycetes 

 giving rise to a peculiar flat process. The acromion and coracoid 

 processes are most developed in the Simiidce and Ateles. 



The relative length of the fore and hind limbs has been already 

 briefly touched upon. The humerus closely resembles that of 

 Man throughout the suborder ; the nearest approximation occurring 

 in the Simiidce. As in the Lemuroidea, this bone never has an 

 entepicondylar foramen, but in many of the American forms it has 

 a supracondylar perforation. The radius and ulna, like the tibia 

 and fibula, are always perfectly distinct throughout their length ; 

 and the hand can be pronated and supinated upon the forearm. 

 Man, the Gorilla, and the Chimpanzee differ from other forms in 

 having no os centrale in the carpus. 



The brain of Apes is always much smaller in absolute dimensions 

 than in Man. Thus, according to Professor Mivart, 1 " the cranial 

 capacity is never less than 55 cubic inches in any normal human 

 subject, while in the Orang and Chimpanzee it is but 26 and 27 

 cubic inches respectively. The relative size of the brain varies 

 inversely with the size of the whole body, but this is the case in 

 warm-blooded vertebrates generally. The extreme length of the 

 cerebrum never exceeds, as it does in Man, two and a quarter times 

 the length of the basicranial axis. The proportion borne by the 

 brain to its nerves is less in the Apes than in Man, as also is that 

 borne by the cerebrum to the cerebellum. In general structure 

 and form the brain of Apes greatly resembles that of Man. Each 

 half of the cerebrum contains a triradiate lateral ventricle, and 

 though in some Cercopithecidce the posterior cornu is relatively 

 shorter than in man, it again becomes elongated in the Cebidce, and 

 in many of the latter it is actually longer relatively than it is in 

 man. The posterior lobes of the cerebrum are almost always so 

 much developed as to cover over the cerebellum, the only exceptions 

 being the strangely different forms Mycetes and Hylobates syndadyhis. 

 In the latter the cerebellum is slightly uncovered, but it is so con- 

 siderably in the former. In Chrysothrix the posterior lobes are much 

 more largely developed relatively than they are in man. The 

 cerebrum has almost always a convoluted external surface. In this 

 group, however, as in mammals generally, a much-convoluted cere- 

 brum is correlated with a considerable absolute bulk of body. Thus 

 in Hapale (and there only) we find the cerebrum quite smooth, the 

 only groove being that which represents the Sylvian fissure. In 

 Simia and Gorilla and Anthropopithecus, on the contrary, it is very 

 richly convoluted. A hippocampus minor is present in all Apes, 

 and in some of the Cebidce it is much larger relatively than it is in 

 Man, and is absolutely larger than the hippocampus major. Of all 

 i Article APE, Encyclopccdia Sritannica, ninth edition. 

 45 



