312 



MAMMALIA. 



an entepicondylar foramen in the humerus. The teeth are 

 deepened and more or less curved, often persistently growing 

 throughout life. The dental series is nearly complete, only the 

 canines being constantly reduced or absent. The neck is short. 

 The bones of the two rows of the carpus alternate ; and there 

 are only three digits on each foot. 



FIG. 178. 



Typotherium cristatum ; skull and mandible, one-quarter nat. size. Pleistocene 

 (Pampa Formation) ; Buenos Aires, Argentina. (After Gervais.) 



Toxodon (fig. 179). The skeleton in the typical genus Toxodon is 

 almost completely known by associated sets of bones in the La Plata 

 Museum. The skull is very massive, with a comparatively small facial 

 region and the premaxillse projecting far in front of the nasals. The 

 orbital cavity is not separated from the temporal fossa. The auditory 

 bullse are small, and the meatus is directed upwards. The two rarni of 

 the mandible are fused at the symphysis, which is deeply channelled. 



i. 2, c. 0, pm. 3 or 4, m. 3 



The dental formula of the adult is .' 



and all 



i. 3, c. 1, pm. 2 to 4, m. 3 ' 



these teeth grow from persistent pulps. The molars and premolars are 

 much curved, and the latter are simpler than the former in both jaws. 

 The upper molars are triangular in section, while the lower molars are 



