MAMMALIA. 



13 



No. 16. Equus fossilis. 



Molar. Remains of the fossil Horse have been found in 

 the uppermost Tertiaries and the Quaternary of many parts 

 of Europe and America. These remains are in the main 

 mohxr and incisor teeth, which are usually noted under tlie 

 name of E. fossilLs, altliough some authors undertake to dis- 

 tinguish several species. This specimen is from the Quater- 

 nary beds of Piedmont, Italy. 



No. 17. [83] Hipparion elegans, Christol. 



Left Hind Foot (cast). This little equine quadruped was 

 tridactyl; for while the two splint-bones alone are retained in the 

 Horse, Zebra and Ass, in the Hipparion they terminated in small 

 digits and hoofs. Such a foot was better adapted for swampy 

 soil, as it would not sink so deeply. The hoofs dangled behind 

 like the spurious hoofs of the Ox. The Hipparion was the first 

 transitional form discovered between the Eocene Perissodactyla 

 .and the modern Horse, and its discovery supplied a powerful 

 argument for the development hypothesis. This specimen was 

 found in the lower Pliocene at Cucurron, France, and belongs to 

 the Museum of Natural History in Lyons. Size, 14 x 13. 



No. 18. [85] Anchitherium Bairdii, Leidy. 



Skull and Lower Jaw (cast). This old-toed Ungulate resembles the 

 PalMotherium in its dental structure, but is very much like the Horse in its 

 skeleton. The cranium has a short sagittal crest and a large, broad forehead ; 

 the skull is relatively shorter than that of the Horse; each jaw contains six 

 incisors, two canines, and seven molars. It is near to Mio'hipp\is, Marsh. 

 These remains were found in the Mauvaises Terres (Miocene), Nebraska, and 

 are preserved in the Museum of the Academy of Natural Sciences, Philadel- 

 phia. Size, G X 4. 



FAMILY PAL2E0THERIDiE. 



This group is closely related to the early members of the Equidw, 

 and Cope includes here some of the supposed ancestors of the 

 Horse. The family is entirely extinct since the Pliocene. 



