364 LAND MAMMALS IN THE WESTERN HEMISPHERE 



obscuring the plan. In the true swine the teeth are much 

 larger and covered with innumerable wart-like cusps, large 

 and small, seldom arranged according to any definite 

 plan. 



In the following particulars the modern peccaries show 

 advance over the Old World swine : (1) the last lower premolar 

 has taken on the molar-pattern, a very exceptional featiu-e 

 among the artiodactyls ; (2) the ulna and radius are coossified ; 

 (3) there are but two functional digits in each foot ; the fore 

 foot has, in addition, two complete, but very reduced and slender, 

 lateral digits and the hind foot only one, whereas in all the pigs 

 of the eastern hemisphere there are four functional toes in each 

 foot ; (4) in the hind foot the two functional metatarsals, the 

 third and fourth, have coalesced to form a "cannon-bone," 

 a structure which is not found in any other family of the sub- 

 order; (5) the stomach is complex, approximating that of 

 a ruminant. 



In the North American Pleistocene the predominating kind 

 of peccary was a genus {^Platygonus) which was more ad- 

 vanced than the existing form (Tagassu), and, to all seeming, 

 better fitted to survive, though for some inexphcable reason it 

 failed to do so. It was a considerably larger animal, with 

 proportionately longer and heavier legs. Its molar teeth are 

 of special interest because they reproduced a type which has 

 been so often repeated and independently acquired in so many 

 different groups of mammals. In this molar the two conical 

 cusps of each pair were fused into a high, transverse ridge or 

 crest. Precisely the same modification took place among the 

 true swine in the genus ^Listriodon of the French middle 

 Miocene. ]Platygonus first appeared in the middle Pliocene, 

 and its predecessor in the lower Pliocene and upper Miocene 

 showed the crests of the molars in process of formation. In the 

 latter stage it was accompanied by a true peccary with tuber- 

 culated teeth, which differed from the modern species in the 

 simplicity of the hindmost premolar, which had not taken on 



