294 UNGULA TA 



the earliest known, Anoplotherium, was fully described by Cuvier 

 from remains found in the Paris gypsum-beds (Upper Eocene). 

 Its forty-four teeth formed a series unbroken by a gap or diastema, 

 and were of uniform height (as in Man alone of existing mam- 

 mals). Its tail was long, with large chevron bones underneath, 

 not usually found in Ungulates, and there were either three or 

 two toes on each foot. It was in many respects a much- 

 specialised form, apparently not on the line of descent of any of 

 the existing groups. 



Dacrytherium is an allied genus whose dentition leads on to that 

 of the smaller Xiphodon. The latter genus is characterised by the 

 compressed and elongated form of the crowns of the first three 

 premolars, which thus approximate to those of the Chevrotains. 

 There were only two functional digits to the feet. The so-called 

 Hyopotamus picteti, of the Swiss Eocene, is a species of Dacrytherium. 



Ccenotheriidce. The typical representatives of this family are 

 small animals not larger than the Chevrotains, with the full comple- 

 ment of teeth, generally no marked gap in the series, and the 

 crowns of the upper molars carrying two columns on the anterior 

 and three on the posterior half of the crown precisely the reverse 

 of the arrangement obtaining in the Anthracotheriidce. The known 

 forms are from the Upper Eocene and Lower Miocene of Europe. 

 In Ccenotherium the molars are selenodont, while they are bunodont 

 in Dichobunus. Homacodon, of the Bridger Eocene of the United 

 States, is closely allied to the the latter. The first lower premolar 

 of Didwbunus assumes the form and function of a canine. Spanio- 

 therium (Metriotherium) is a much larger form, in which the molars 

 are not unlike those of Anthracotherium, if the arrangement of the 

 cusps were reversed ; it occurs in the Eocene Phosphorites of 

 France. It is suggested that the Tylopoda may have originated 

 from this group. 



Tapirulus is a small Eocene Artiodactyle with the columns of 

 the upper molars, which are somewhat like those of Hyopotamw, 

 tending to form transverse ridges ; its family position is uncertain. 



Dichodontidce. The European genera included in this family all 

 have quadritubercular selenodont molars, and show signs of approxi- 

 mating more or less closely to existing types. Dichodon, from the 

 Upper Eocene and Lower Miocene, has the full complement of teeth, 

 which show no diastema, and have low crowns. The fourth upper 

 premolar has four columns, like the true molars, and the corre- 

 sponding lower tooth three complete lobes ; these features being 

 unknown in any other Selenodonts. In Lophiomeryx, of the same 

 beds, the somewhat higher crowns of the molars approximate to 

 those of the Cervidce, but the hinder lobes of the upper ones are 

 imperfectly developed ; the genus may be allied to the Tragulidce. 

 In the small Gelociis, of the Lower Miocene, the molars are not 



