UNQULATA. 



327 



as a rhinoceros, with the skull 0'5 m. in length. P. cratsum, P. medium, 

 and others are smaller forms. 



FIG. 186. 



Palaotherium magnum; restoration of skeleton by Cuvier, about one-thirtieth 

 nat. size. U. Eocene (Gypsum) ; Montmartre, Paris. 



Anchitherium (fig. 182). The skull and dentition in this genus 

 are remarkably similar to those of Palceotherium, but the incisors begin 

 to exhibit an apical pit or depression. There is still no trace of cement 

 in the hollows of the dental crowns. The features in which the skeleton 

 differs from that of Palceotherium tend towards the corresponding 

 characters of the modern horses. The ulna and fibula are complete, 



Mesohippus bairdi; left upper molar-premolar series, nat. size. L. Miocene 

 (White River Formation) ; Dakota, p, protocone ; pp, metaconule. (After 

 Osborn.) 



though extremely slender, and they are more or less anchylosed with 

 the radius and tibia respectively. The three digits (fig. 182) are no 

 longer of equal size, nos. n and iv, though complete, being shorter and 

 scarcely more than half as stout as the median no. in. The typical and 

 only satisfactorily known species is Anchitherium aurelianense, with the 

 skull about 0'25m. in length, from the Middle Miocene of France, Wiirtem- 

 berg, Bavaria, and Austria. 



