590 CHORD AT A, 



to the rest of the Primates they have only two molars. Their dental 

 formula is ItII • All the digits except the hallux are clawed and the 

 pollex is present but not opposable to the other digits. They have a 

 long, bushy tail and are strictly arboreal. 



Family 2. — Cebidae. — The American Monkeys. They are confined 

 to Neogoea, are strictly arboreal and often have prehensile tails. 

 Their dental formula is Ixtf ? hence they differ from the Hapalidce in 

 having an additional molar. They also have a pollex to a large 

 extent opposable. They include the Spider-monkeys and Capuchins. 



Fig. 396. — Front View of Skull of a Gorilla. 



Note forward position of the complete orbits, the (vertical) sagittal crest, 

 the two incisors (— ) and the rather longer canines. 



Family 3. — Cercopithecidae. — All this family of Monkeys is found 

 in the Old World, mainly in the Oriental and Ethiopian regions. 

 The tail is not prehensile but is often of great length. There are 

 usually brightly coloured ischial callosities. The pollex, if present at 

 all, is always opposable, and the front -limbs are always markedly 

 shorter than the hind-limbs. The dentition is fiff. All the best 

 known monkeys belong to this family, including the baboons {Cyno- 

 cephahis) of Africa, which are not arboreal but frequent rocky regions 

 in conmiunities, and the familiar Macaques {Macacus) of Asia. 



Family 4. — Simiidae. — The family of Anthropoid Apes. They 

 are all found in the Old World and comprise the Gorilla and Chim- 

 panzee of equatorial Africa, the Orang of Borneo and the Gibbons of 

 the Oriental region. They mostly have no tail ; there are never ischial 

 callosities. The pollex is always opposable and the front-limbs always 

 exceed the hind-limbs in length. The dentition is fxM • 



