1358 



CLASS MAMMALIA. 



hinder lobe more or less completely aborted, the third lower premolar is 

 less complex than the fourth, the first lower premolar is absent, and the 

 corresponding" upper tooth may also be wanting ; when the latter tooth 

 is present it is sometimes preceded by a milk-molar. In this group P. 

 Javali, from the Quercy Phosphorites, is remarkable for the presence of 

 a considerable quantity of cement in the cheek-teeth, and for the approxi- 

 mation of the upper canine to the premolars and its apparent separation 

 from the incisors. P. minus from the Paris basin is the smallest species 



Fig. 1230. — Reduced restoration of Pal&otherium magnum, after Cuvier. 

 Upper Eocene, France. 



C. -, Pm. I 



I 



— , M, - ; and the cheek-teeth are nearly 

 3 3 



of the genus ; while P. codiciense, from the Middle Eocene of France, has 

 its fourth upper premolar as simple as in Lofthiodo7i and Hyrachyus, and 

 thus shows how extremely intimate is the relation between all these early 

 forms of the suborder, and how very difficult it is to give any good dis- 

 tinctive characters of the families into which it is convenient to divide 

 them. 



In Anchilophus, of the Upper Eocene of the Continent, the dental 



formula is I. -, 

 3 



intermediate in structure between those of Pachy- 



nolophus and Anchitherium. The last upper pre- 

 molar is as complex as the first true molar ; there 

 are well-marked ridges on the outer columns of 

 the upper true molars ; the last lower true molar 

 has a large third lobe ; and the diastema is elon- 

 gated. The genus Epihippus from the Upper 

 Eocene of North America, which is reckoned 

 by some writers as being on the direct ancestry 

 of the Horse, has been placed here by Dr 

 Schlosser. The genus forming a step in advance 

 of Anchilophus is Anchitherium, typically from 

 the Middle Miocene of Europe, but with which the contemporary 

 North American forms described under the names of Mesohippus 



Fig. 1 23 1. — A left 

 upper true molar of 

 A nchitherium aureli- 

 anense ; from the Mid- 

 dle Miocene of France. 



