1330 CLASS MAMMALIA. 



the preceding, also has simple premolars ; Myxochoerus shows less 

 completely selenodont teeth ; while those of Tapirulus approximate 

 to the molars of the Tapiridce. In another direction we have 

 Dacrytherium and Pksidacrytherium, from the Upper Eocene of 

 France and England, in the former of which the first upper incisors 

 of either side are separated from one another by a wide interval, 

 while the first three premolars are more completely secant than in 

 the type genus. The dental type of Dacrytherium leads on closely 

 to that of Xiphodon, which, in accordance with the views of Pro- 

 fessor Riitimeyer, is therefore placed in the same family, although 

 some writers make it the type of another family, which is taken to 

 include either Ccenotherium (Flower), or 

 Dichodon (Schlosser). The true molars 

 are like those of the type genus Anoplo- 

 therium, although more completely seleno- 

 dont ; but the first three premolars (fig. 

 120s) are much elongated and com- 



tig. 1205. — The last two left -\ r • i« • 



upper premolars and first true pressed ; and the functional digits were 

 ^Vvl^olintof^m^Ur^ reduced to two in each foot. In the 

 typical forms there was no diastema in 

 the dental series (which comprises the full typical number), but in 

 certain smaller forms, separated by some writers under the name of 

 Xiphodontotheriu7?i, a distinct diastema was developed. The Xipho- 

 donts were animals of slender build, with limb-bones partly re- 

 sembling those of Anoplotherium, and partly those of the more 

 specialised Selenodonts ; they are characteristic of the Upper 

 Eocene of England and the Continent, the largest species being 

 X. magnus, and the smallest X. (Xiphodo?itotherium) secundarius, 

 of the Quercy Phosphorites. This genus, although not in the direct 

 line, shows how a transition can be effected from the higher Anthra- 

 cothe?'iidce to the Dichodontidce. Rhagatherium, from the Upper 

 Eocene of Switzerland, is an allied genus. Finally, Dr Ameghino 

 refers to this family the genus Brachytherium, from the Tertiary of 

 South America ; while Dr Schlosser would include in it the genus 

 Tetraselonodon, founded on teeth from the Quercy Phosphorites, 

 which have only four columns on the crown. 



Family Cenotheriid^e. — Following the classification of Pro- 

 fessor Riitimeyer the next family we have to consider is that of 

 which the type genus is Ccenotherium. All the genera have the full 

 complement of teeth, and there are usually five columns, or cusps, 

 on the crowns of the upper true molars (which may be either seleno- 

 dont or bunodont) ; two of these columns being placed on the 

 anterior and three on the posterior lobe of the teeth, thus reversing 

 the arrangement obtaining in the Anoplotheriidce. The type genus 

 Ccenotherium comprises a number of species of small animals not 



