PERISSODACTYLA. 321 



in the fore-foot ; and in the extinct Eoliippus there is even 

 a rudimentary first digit or pollex. Lastly, in the extinct 

 Coryphodonts, which, as before said, might with some advan- 

 tage be placed in a separate section {Teleodactyla),t\ie feet are 

 furnished with the full complement of five digits on all the 

 feet, and all of these are sufficiently developed to touch the 

 ground. Provisionally admitting these ancient live-toed types 

 into the Perissodadyla, we may divide this section of Un- 

 gulates into the seven principal families of the Coryjphodon- 

 tidce, Bhinoceridm, Tapiridm, Brontotheridm, Palceotheridm, 

 Macrauchenidce, and Equidm. Of these, the families of the 

 Bhinoceridce, Tapiridce, and EquidcB alone survive ; and widely 

 separated as they are in many important characters, the in- 

 tervals between them are to a large extent filled up by 

 an extensive series of fossil forms. 



Fam. 1. Corypliodontidcc. — In this family is comprised the 

 genus Corypliodon only, this being apparently identical with 

 the Bathmodon of Cope. First founded by Owen upon 

 fragmentary remains discovered in the Eocene Tertiary of 

 Britain, the characters of the genus have now been largely 

 elucidated by Professor Marsh from the much more ample 

 material obtained from strata of the same age in North 

 America. The genus Coryphodon comprises large Tapir- 

 like animals, all belonging to the period of the Eocene 

 Tertiary, and having an average size about equal to that of 

 the living Tapirs. The skull (fig. 625, a) is of the Perisso- 

 dactyle type, and is hornless, the comparatively small size of 

 the nasal bones indicating that the nose was not prolonged 

 into a proboscis. The brain is remarkably small, and of an 

 altogether inferior type of organisation — casts of the brain- 

 case indicating that the cerebellum was large, the cerebral 

 hemispheres much reduced in size, and "the olfactory lobes 

 large and entirely in advance of the hemispheres " (Marsh). 

 The dentition is complete, tbe dental formula being — 



3—3 1—1 4—4 3— 



o 



c 3 r ; pm ; VI = 44. 



3—3 1 — 1 '- 4-4- 3 — 



The canines are not excessively developed, and the molars 

 are of the Tapiroid type, and have two transverse crests or 

 VOL. II. X 



