656 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 57. 



posterior borders directed outward to relatively long and thick, the upper 



a degree that were the planes of their ones with their loug axes nearly pui- 



long axis extended they would con- allel ; lower canines less curved and 



verge to meet within the incisive bor- less divergent than in Tayassu. 

 der; lower canines strongly curved 

 and widely divergent. 



7. Diastemata behind canines about 7. Diastemata behind canines con- 

 equaling length of premolar series. siderably less than lengtn or premolar 



series. 



These definitions seem to clear up to some extent our understand- 

 ing of the living peccaries, especially in their bearing on the Pleisto- 

 cene genera, and suggest the following modifications and additions 

 to the definitions proposed by Hay,^ for Platygonus and Mylohyus. 



Genus PLATYGONUS LeConte. 



Peccaries with snout moderately lengthened; functional digits 

 two (III and IV) on each foot, other digits, if present, represented 

 only by simple splints or nodules of bone ; outer lower incisors much 

 reduced, frequently wanting; all premolars above and below more 

 simple than the molars, each consisting of a single conspicuous pair 

 of moderately elevated, transversely placed cusps and usually with 

 heavy basal cingulum, the lower premolars having in addition a 

 transverse row of low but well-developed heel cusps, tending strongly 

 tovv'ard the condition found in Pecari, but less advanced in this re- 

 spect; molars similar to but more progTessive than those of Pecari^ 

 being composed of two pairs of moderately elevated, transversely 

 placed cusps, which form continuous transverse ridges even in teeth 

 which are but slightly worn; modifications of the upper and an- 

 terior portions of the face, and relative positions of the supra-orbital 

 foramina and the suprafacial sulci more nearly like the modifica- 

 tions found in Pecari than in Tayassu; space between the incisive 

 border and the canines laterally constricted, and the maxillary 

 buttress above the canines formed much as in Pecari but more 

 stronly developed than in the living genus. 



Genus MYLOHYUS Cope. 



Peccaries with long slender snouts; digits reduced to single pairs 

 in the hind feet only, the fore feet retain a second, small but almost 

 functionless pair of lateral digits ; outer pairs of incisors, above and 

 below^, wanting; last two pairs of premolars, above and below, sub- 

 equally four cusped, completely molariform, the others submolari- 

 form, all with no basal cingulum; molars with four principal little 

 elevated, subsequal cusps, tending to pair transversely about as in 



* See pp. 217 and 225 respectively of his treatise on The Pleistocene Mammals of Iowa, 

 already cited. 



