34 ON THE EXTINCT MAMMALIA OF 



A small fragment of the upper jaw attached to the same mass of matrix, and be- 

 longing to the same individual as the cranium just described, served to indicate the 

 genus to which the animal belonged. It consists of a small portion of the left 

 maxillary bone containing the three tubercular molar teeth, represented in figure 5, 

 plate I. 



Notwithstanding the worn condition of these teeth, much of the enamel having 

 been abraded away, they are observed to bear a near resemblance to the correspond- 

 ing ones of the Wolf and of the extinct Amphicyon major. They have the same 

 constitution as in these animals, and are intermediate in size to those of the Prairie 

 Wolf and the Red Fox. 



The third tubercular molar, peculiar to the genus Amj^Tiicyon, has a small trans- 

 versely oval crown, with two tubercles, and is inserted into the jaw by a single fang. 



Another small fragment of an upper jaw, belonging to a diiFerent, smaller, and less 

 aged individual than the former, contains the sectorial molar, the succeeding pair of 

 tubercular molars, and part of the alveolus for the third. The teeth are represented 

 in figure 6, plate I, in which the tubercular molars are seen to be like the corres- 

 ponding ones represented in figure 5, but are smaller. The sectorial molar has the 

 same form, constitution and size as that of the Red Fox, except that it is thicker at 

 the fore part. 



A third small fragment of an upper jaw, belonging to a different individual from 

 the former ones, contains the first and second tubercular molars and the sockets for 

 the third. The teeth have nearly the same size as those of the last described frag- 

 ment, but the second is slightly larger. 



The tubercular teeth in all the three specimens described differ slightly in outline 

 and size, as the corresponding teeth do in different individuals of any recent species 

 of Wolf or Fox. 



A fragment of the lower jaw belonging to the same individual as the cranium 

 above described, represented in figure 2, plate I, consists of the posterior portion of 

 the left ramus, containing the heel of the sectorial molar, and the two tubercular 

 molars. 



The jaw fragment in form and proportions bears a close likeness to the correspond- 

 ing portion of the same bone in its giant relative, the Amphicyon major, as 

 represented in plate, Subursus, xiv, of M De Blainville's Osteographie. It is pro- 

 portionately very much more robust than in recent canine animals, while the 

 contained teeth are proportionately rather smaller. It is absolutely larger and 

 stronger than in smaller varieties of the Canis occidentalis. The body of the jaw 

 below the back molars is considerably deeper, the coronoid process, while having 

 nearly the same length, is very much wider, the external muscular fossa is very much 

 deeper and capacious, and the condyle is far more robust. The base of the jaw rises 



