SKELETON. VISCERA. 655 



entepicondylar foramen, and the radius and ulna are separate 

 and capable of pronation and supination. The carpus generally 

 has a centrale (absent in Homo, Gorilla and Anthropopitkecus), 

 and the thumb is always opposable when present ; it is occa- 

 sionally absent. 



The femur has no third trochanter ; the tibia and fibula are 

 separate, and the astragalus has a convex tibial surface with a 

 lateral process for the fibula. The hallux is shorter than digit 

 No. 2, and is opposable, except in Homo. The digits always 

 have flat nails except in the Hapalidae. 



The cerebrum is large and its surface is usually well convo- 

 luted (except in a few American monkeys) ; it completely or 

 nearly completely covers the cerebellum. The lateral ventricle 

 has a posterior cornu and hippocampus minor. 



The uterus is without cornua. There is one pair of 

 pectora mammae, and the cUtoris is not perforated by the 

 urethra. 



As already stated, most apes are arboreal and inhabit the 

 forests of the warmer countries. Only a few lead a solitary life. 

 Most of them live together in large companies which are led by 

 the largest and strongest male. They feed chiefly on fruit 

 and seeds, but also on insects, eggs and birds. The female 

 produces only one young (rarely two or three) at a birth, 

 and they protect and tend their offspring with great affec- 

 tion. Intellectually the apes take with the dog and elephant 

 the highest place among mammals after man. 



There are four families. Two of these, the Hapalidae and 

 Cebidae, are confined to the New World, and are sometimes 

 grouped together as the Platyrrhina ; the other two, Cerco- 

 pithecidae and Anthropomorphidae, are, with the exception of 

 one genus {Homo), found exclusively in the Old World, and are 

 sometimes grouped together as Catarrhina. The only Euro- 

 pean monkey is the Barbary ape {Macacus innuus), which is 

 found on the precipices of Gibraltar. 



The Platyrrhina are distinguished by possessing a broad carti- 

 laginous internasal septum, by the absence of a bony external 

 auditory meatus, and by the fact that the alisphenoid usually 

 meets the parietal on the side of the skull, and the jugal joins 

 the parietal. They are without cheek pouches and ischial 

 callosities ; the last lower molar is usually without a talon and 



