ITS ANCESTOKS AND RELATIONS 



81 



diverging in details, although constructed in the main 

 upon the same type, the best known of which are in- 

 cluded in the genera Lojphiodon of European and Hyra- 

 chyus of American formations. Of the latter, remarkably 

 complete skeletons have been discovered and fully 

 described by Leidy, so that its osteology is now com- 

 pletely known. A few further stages of modification 

 lead to the Palceotherium of the Paris basin (late Eocene), 

 an interesting form from its association with the illus- 

 trious Cuvier, who in 1804 established its existence, and 

 by comparison of its bones with those of all known recent 

 species of animals, demonstrated for the first time to the 

 satisfaction of the scientific world that animals had in- 

 habited the earth other than those now found upon its 

 surface. By this demonstration he laid the foundation 

 of the study of palaeontology of vertebrated animals — a 

 study which has developed in this comparatively short 

 period of time to such a marvellous extent, and which 

 has still before it a future of unbounded promise. 



By the time that the Palseotherium appeared, the 

 group of Perissodactyles was already breaking up into 

 different families by the gradual change in various 

 directions from the primitive Lophiodont type. Some 

 were passing step by step into tapirs, which still exist 

 and retain much more of the original characters of the 

 primitive ungulates of the Eocene period than any of 

 the others now remaining on the earth, having indeed 



