THE ARTIODACTYL UNGULATES 201 



exhibit molars, the protocone and protoconid of which are not 

 round but already somewhat crescentic in shape. 



SUIDAE 



First among the Artiodactyla Ave take the Pigs and the 

 nearly related Hippopotami. The former family includes the 

 Swine of the Old World and the American Peccaries together 

 with a vast number of other forms now extinct. The original 

 placental formula: 



1 1, C-v.PT.M-l.tatal.44. 



o I 4 o 



is found in some species of this family although frequently the 

 more anterior premolars tend to be lost. 



We must pass over the Peccaries which are close relations of 

 the true Swine, more primitive in some respects and more ad- 

 vanced in others but with simpler molars and non-everted 

 canines. 



The example chosen to represent the Suidae namely the 

 Red River Hog, Potamochoerus porcus of West Africa (Fig. 

 72) shows molar teeth in some respects simpler than those of 

 the common domestic Pig, for they are less tuberculated and 

 the last lower molar is not so elongated. This animal lives in 

 moist forests and on river banks and like other members of 

 the family feeds upon roots and carrion. The dental for- 

 mula is: 



l|, Cy,P-|,M|. total 40. 



The median upper incisors separated at their bases and ap- 

 proximating at their tips, and the procumbent lower incisors 

 recall the arrangement already noted in Marsupials and to a 

 less extent in Insectivores. The canines have persistently grow- 

 ing roots, are tusk-like and very specialized. Both upper and 

 lower tusks project laterally and are triangular in section. 



