786 



MAMMALIA. 



except in man ; the nails are almost invariably flat, except 

 in marmosets; the cerebral hemispheres have in most cases 

 numerous convolutions, and usually cover the cerebellum ; 

 the stomach is simple except in Semnopithecus and its 

 relatives, in which it is sacculated ; there is a caecum which is 

 often large; there are two mammae on the breast; the 

 uterus is simple ; the testes lie in a scrotum ; the penis is 

 pendent; the placenta is metadiscoidal, being developed by 

 the concentration of the villi from a diffuse area into a well- 

 defined disc. Most Anthropoidea are arboreal, gregarious, 

 uniparous, and tropical or sub-tropical. 



CONTRAST BETWEEN PLATYRRHINA AND CATARRH IN A 



The New World Platyrrhina are in many ways so different from the 

 Old World Catarrhina that a twofold (diphyletic) origin of the monkey 

 Border is not improbable. There are no transitional forms, and the 

 distribution of the extinct representatives corresponds with that of the 

 living forms. 



PLATYRRHINA CATARRHINA 



Broad cartilaginous internarial Narrow, 

 septum. 



Nostril directed outwards. 



Tympanic bone not more than a 

 ring. No bony external audi- 

 tory meatus. 



Tympanic bulla. 



Alisphenoid usually meets the 

 parietal on the side of the 

 skull, and the orbital plate of 

 the jugal meets the parietal. 



A large orbito-temporal fora- 

 men. 



Three premolars. 



Tail often prehensile, with 

 never fewer than 14 verte- 

 bne* 



No cheek -pouches. 

 No ischial callosities. 



Downwards. 



Forms a bony external auditory 

 meatus. 



None. 



Frontal usually meets the squa- 

 mosal, and the jugal does not 

 meet the parietal, being 

 hindered by the frontal and 

 alisphenoid. 



Small. 



Two premolars. 



Tail not prehensile, sometimes 

 . practically absent. 



Usually present, except in Apes. 



Present, except in Gorilla, Orang, 

 and Chimpanzee. 



