428 THE VERTEBRATE SKELETON. 



The incisors and canines of Hippopotamus are very large 

 and grow continuously. The genus Sus, which affords a good 

 instance of an omnivorous type of dentition, has the regular 



unmodified Mammalian dental formula i - c - pin j m - , total 



o 1 4 o 



44. The canines, specially in the male, are large and have 

 persistent pulps, and the upper canines do not have the usual 

 downward direction but pass outwards and upwards. In the 

 Wart Hog, Phacochaerus, they are enormously large, but a 

 still more extraordinary development of teeth is found in 

 Babirussa. In the male Babirussa the canines, which are with- 

 out enamel, are long, curved and grow continuously. Those of 

 the upper jaw never enter the mouth, but pierce the skin of 

 the face and curve backwards over the forehead. The dental 



21 23 

 formula of Babirussa is i J c ^pm -m^, total 34. 



1 Jo 



The Wart Hog has a very anomalous dentition, for as 

 age advances all the teeth except the canines and last molars 

 show signs of disappearing ; both pairs of persisting teeth are 

 however very large. 



Various extinct Uiigulata such as Anoplotherium have 

 teeth which are intermediate in character between the bun- 

 odont and selenodont types. Anoplotherium has the regular 

 mammalian series of forty -four teeth. The crowns of all the 

 teeth are equal in height, and there is no diastema an 

 arrangement found in no living mammal but man. 



We come now to the selenodont Artiodactyla. 



The Tylopoda camels (Camelidae) and Llamas (Auchenii- 

 dae) when young have the full number of incisors, but in the adult 

 the two upper middle ones are lost. The molars are typically 

 selenodont and hypsodont 1 . In the Camel the dental formula 



11 33 



is i c ^pm ^m^, total 34. The upper incisors, canines and 

 o 1 2i o 



first premolars of the Camel are very small teeth, and the 



1 See p. 345. 



