554 UNGULATES. 



like those above, are larger than in the -/Elian Wart Hog. The 

 stump of a premolar is retained on one side, separated bj^ an 

 interval of an inch from the last molar, the rest having been 

 shed, as in the upper jaw : the grinding surface of the molar is 

 of the same length as that above, and is live lines in breadth : 

 it presents a middle row of eight columns and two lateral rows of 

 seven each, twenty-two in all. 



198. Succession. — Before proceeding to the Peccari, which deviates 

 still further in its dentition from the characteristics of the Suidce and 

 represents that of the extinct forms of the family, which lead on 

 the one hand to the Plantigrades and on the other, by closer steps 

 of affinity, to the Hippopotamus, I shall notice the succession and 

 structure of the teeth in the more typical Hogs. 



The first or deciduous dentition of the Hog consists of: — 



Incisors — : canines — : molars — : == 28. 



3—3 ' 1—1 ' 3—3 



The first milk incisor, above, is large, oblique, trenchant, and 

 with a depression on the inner surface of the crown : the second 

 and third are small and pointed. The first and second incisors, 

 below, are trenchant and oblique ; and have the indentations and 

 ridge slightly marked on the upper or inner side of the long and 

 narrow crown ; the third is pointed. The canines are feeble and 

 have their normal direction in both jaws, the upper ones des- 

 cending according to the general type, which is not departed 

 from until at a later period of life. The first and second 

 deciduous molars (PI. 140, fig. 2, d 1, d 2) have simple com- 

 pressed conical crowns crenate at the edge, and with an anterior 

 and posterior basal tubercle ; the second is a little larger than 

 the first : the third manifests the characteristic increase of size 

 and complexity, yet is kept within the bounds of the more 

 common type : in the upper jaw it has four principal tubercles, 

 and thicker ridges at the fore and back part of the base of the 

 crown : when the enamel is worn from the middle of the sub- 

 dividing valley, and the dentine of the two tubercles is united, 

 the pattern closely resembles the characteristic trefoil of the 

 grinders of the Hippopotamus. In the lower jaw, the last 



