MAMMALIA. 



25 



Pliocene Hipparion. The grinding teeth in these animals Table-case 

 are less deepened than in the last-mentioned genus, those of ^* 

 the earlier forms being indeed quite low-crowned and only 

 fit for comparatively succulent vegetation. The side-toes 

 tend to become larger and touch the ground as they are 

 traced back in geological time. Typical remains of AncJii- 

 thcrium (Fig. 18, 3), from the Middle Pliocene of Europe, and 

 of Mcsohip])ns, from the Oligoceue of Xortli America, are 

 exhil)ited in Tal)le-case 5. 



The Eocene horse-like animals are still smaller than the Pier-case 9. 

 later forms just mentioned, and their immediate connection Table-ease 

 with the horses would be difficult to recognise if all the links 

 of Oligocene and Miocene age remained unknown. A plaster 



Fig. 14. — Left upper teeth in maxilla of Falieothcrium crassum, from the 

 Upper Eocene Gypsum of Moutmartre, Paris; three-quarters nat. size. 

 la-3a, three molars ; Ip-ij), four premolars ; other letters indicate 

 various tooth-cusps, (.\fter A. Gaudry.) 



cast of Protoruldppus venticolus from the Wind Eiver Forma- 

 tion of Wyoming, U.S.A., exhil)ited in Pier-case 9, affords a 

 good idea of one of these animals about as large as a fox ; 

 and tliere are actual remains both of this and of the closely 

 related Hyracothcrinm (Fig. 13, 4) fi'om the Lower Eocene 

 of the London Basin in Table-case 5. The ridojes on the 

 grinding teeth are more or less su])divided into tul)ercles ; 

 the neck is not very mobile ; the fore limb lias a complete 

 and separate ulna, allowing some power of twisting, and 

 there are four spreading toes ; the hind limb has only three 

 complete toes. Paleeothcrium and Lophiodon are allied genera 

 from the Eocene of Europe, and comprise some species as 

 large as rhinoceioses. Paleeotlicrium (Figs. 14, 15) was first 



