R. Lydelilier — On Fossil Mammalia. 71 



represented in the accompanying woodcut (Fig. 6). This ramus is 

 complete, with the exception of the symphysis. In general form it 

 resembles the mandible of ffyopotamus,^ and of certain species of 

 Anthracotherivm, e.g. A. hippoideam, Riitimeyer.- There are six 

 cheek-teeth in apposition, in advance of which there is a long 

 diastema, and then the broken base of a tooth which is doubtless 

 the canine. The three true molars correspond exactly with the 

 Egerkingen teeth figured by Professor Eutimeyer, and are of a 

 brachydont type, with an imperfect selenodont structure, and having 

 a small tubercle at the entrance to the external valleys. The general 

 structure of these teeth is very similar to that found in Anthraco- 

 therium Mppoideim, and they are more brachydont than in typical 

 species of Hyopotamus. The fourth premolar has fore-and-aft talons, 

 with a large inner cusp ; the latter being found of smaller size in 

 some species of Hyopotamns and Anthracotherium. The third and 

 second premolars have compressed conical crowns, with very minute 

 talons ; and are each inserted by two roots. There is no trace of 

 the first premolar. 



Fig. 6. Anthracotherium G>esslyi (Meyer). The right ramus of the mandible, 

 and the lower dentition. (B.M. No. 29713.) \. 



In the described species of Anthracothenum (e.g. A. hippoideum) 

 the first premolar is usually situated in the middle of a short 

 diastema occurring between pm. 2 and the canine; and in Hyopo- 

 tamus, pm. 1 is frequently situated very close to the canine, and falls 

 out at an early period of life. The lower jaw under consideration 

 evidently belongs to a specialized form, whose molar teeth agree 

 with those of Anthracotherium, and the brachydont species of 

 Hyopotamus (e.g. H. porcinus). 



^ Ibid. pi. xxi. 



- Denkschr. schw. nat. Ges. vol. xv. art. 8, pi. i. (1857). 



