PERISSODACTYLA. 



593 



is always absent. The cerebrum is well convoluted. The 

 mammae are inguinal, and the testes generally descend into a 

 scrotum or project from the inguinal canal. The placenta is 

 diffused. 



There are only tliree living genera ; Tapir, Equus and Rhino- 

 ceros, hxxt the number oi extinct forms known is very great. The 

 earliest of these are from the Eocene. 



Fam. 1. Tapiridae.* Short-haired forms of medium size with mobile 

 proboscis, i ^ c \ p *^* m § ; all grinding teeth brachyodont, with two 

 transverse ridges (bilophodont) ; p 1 of the u. jaw 

 with a milk predecessor ; posterior premolars like 

 the molars except in the oldest fossil forms ; last 

 lower molar without a posterior lobe. Mantis 

 with 4 digits, the ulnar digit not reaching the 

 ground, pes with 3 digits, each digit hoofed. 



The orbits are not enclosed by bone, the 

 frontals being devoid of a postorbital process ; 

 the premaxillae are small and the nasals widely 

 separated from them ; the postglenoid and par- 

 occipital processes are large ; the tyi^panic is 

 reduced. Ulna and fibula well developed and 

 separate from the radius and tibia. They are 

 first found fossil in the Lower Eocene of Europe 

 and N. America and endure there until the 

 Pliocene. 



Tapirus Cuv. Vertebrae, C 7, D 18, C 5, S 6, 

 C 12 ; dentition *|cipimf; the third upper 

 incisor is larger than the \ipper canine but the 

 lower canine is larger than the third incisor and 

 bites between the third incisor and canine of the 

 upper jaw ; considerable diastema between the 

 canines and premolar ; the premolars except the 

 first resemble the molars. There is no distinct 

 scrotum. The two mammae are inguinal. The 

 placentation is diffuse. They are nocturnal, 

 inoffensive herbivorous animals frecjuenting forests 

 and the neighbourhood of water. There are 5 species, four of wliich are 

 neotropical, the other being oriental in the Malay Peninsula and Sumatra. 

 The genvis is first met with in the Miocene. It is found in the Miocene 

 and Pliocene of Em'ope and Asia and in the Pleistocene o.f America. 



There is a number of extinct genera. These vary from the size of a 

 rabbit to that of a rhinoceros. Some of them are united with the tapir 

 and some in a sub-family the Lophiodontinae, which show affinities to the 

 extinct Palaeotheridae. 



Fig. 309.— Tapirus 

 americanus L. 

 Left manus, x ^. 

 (from Flower). 



Extinct genera. Lophiodon f Cuv. 



P 



m I ; Eocene of 



* Wortman and Earle, Bull Ainer. Mus. N. Hist., 5, 1893, p. 159. 

 Gaudry, Bull. Soc. Geol. France (3), 25, 1897, p. 315. 



t Osborn and Wortman, Perissodactyls of Lower Miocene Beds Bull. 

 Arner. Mus., 7, 1895, p. 358. Osborn, Amer. Nat., 1892, p. 073. 



2— II. Q Q 



