88 



the crown The posterior division presents two elevated points, conjoined in 

 a crescentoid ridge. The anterior extremity of this ridge joins the front 

 division of the crown. Its more elevated point is external and posterior, and 

 its less developed one occupies the postero-internal corner of the crown. A 

 basal ridge incloses the crown, except internally. 



Each division of the crown of the molars incloses in the arms of its- cres- 

 centoid ridge a depression, which is largest in the posterior division. The 

 crown of the last molar is more prolonged backward than the others, arising 

 from the greater degree of development in this direction of its posterior 

 division. 



In the worn condition of the molars, as seen in Fig. 37, the crescentoid 

 ridges of the divisions of the crown have been so much abraded as to expose 

 broad crescentoid tracts of dentine continuous on the two divisions of the 

 crown. 



The rami of the .lower jaw of Northarctus appear to be co-ossified at the 

 symphysis, and the specimen under consideration was broken off just to the 

 left of the latter. The chin is narrow and convex transversely, and it forms 

 a nearly straight or slightly convex slope of about 45°. The body of the 

 bone is nearly of uniform depth; the relation of depth to length being much 

 greater than in the raccoon and more in proportion with the measurements 

 in the hog and peccary. The outer face of the body is nearly vertical. The 

 base is thick and slightly convex fore and aft. Near the middle, directed in- 

 wardly, it exhibits a strong impression for muscular attachment. 



The angle of the jaw, the back border of the bone, and the coronoid pro- 

 cess are lost. The outer face of the ascending portion of the ramus is 

 depressed into a masseteric fossa extending nearly or quite to the base, but 

 shallow compared with that of ordinary carnivores. The condyle is remark- 

 ably short, and resembles that of some of the monkeys more than that of ordinary 

 pachyderms. It is transversely oval, with the breadth less than twice the 

 fore and aft diameter, which is directed obliquely from without inward and 

 backward. The articular surface is transversely convex and inclines more 

 outwardly than inward. 



The form of the condyle clearly indicates more varied movements in the 

 jaw than exists in the carnivora, and would rather be favorable to the proper 

 reduction of the food of an omnivorous animal. 



A mental foramen occupies a position about midway between the third 



