VERTEBRATE LIFE IN AMERICA. 683 



the modern peccary (Dicotyles), but having a greater number of teeth, 

 and a few other distinguishing features. In the Pliocene, Suillines are 

 still numerous, and all the American forms yet discovered are closely 

 related to Dicotyles. The genus Flatygonns is represented by several 

 species, one of which was very abundant in the Post-Tertiary of North 

 America, and is apparently the last example of a side branch, before 

 the American Suillines culminate in existing peccaries. The feet in 

 this species are more specialized than in the living forms, and approach 

 some of the peculiar features of the ruminants ; as, for example, a strong 

 tendency to coalescence in the metapodial bones. The genus Platygo- 

 nus became extinct in the Post-Tertiary, and the later and existing 

 species are all true peccaries. 



No authenticated remains of the genera Sus, Porcus, Phacochoerus, 

 or the allied Hippopotamus, the Old World Suillines, have been found 

 in America, although several announcements to that effect have been 

 made. 



In the series of generic forms between the lower Eocene Eohyus 

 and the existing Picotyles, which I have very briefly discussed, we 

 have appai*ently the ancestral line ending in the typical American 

 Suillines. Although the demonstration is not yet as complete as in 

 the lineage of the horse, this is not owing to want of material, but 

 rather to the fact that the actual changes which transformed the early 

 Tertiary pig into the modern peccary were comparatively slight, so 

 far as they are indicated in the skeletons preserved, while the lateral 

 branches were so numerous as to confuse the line. It is clear, how- 

 ever, that from the close of the Cretaceous to the Post-Tertiary the 

 Bunodont Artiodactyles were especially abundant on this continent, 

 and only recently have approached extinction. 



The Selenodont division of the Artiodactyles is a more interesting 

 group and, so far as we now know, makes its first appearance in the 

 upper Eocene of the West, although forms, apparently transitional, be- 

 tween it and the Bunodonts occur in the Dinoceras beds, or middle 

 Eocene. These belong to the genus Uomacodon, which is very nearly 

 allied to Helohyus, and bxit a single step away from this genus toward 

 the Selenodonts. By a fortunate discovery, a nearly complete skele- 

 ton of this rare intermediate form has been brought to light, and we 

 are thus enabled to define its characters. Several species of LTomaco- 

 don are known, all of small size. This primitive Selenodont had forty- 

 four teeth, which formed a nearly continuous series. 



The molar teeth are very similar to those of Helohyus, but the 

 cones on the crowns have become partially triangular in outline, so 

 that, when worn, the Selenodont pattern is clearly recognizable. The 

 first and second upper molars, moreover, have three distinct posterior 

 cusps, and two in front ; a peculiar feature, which is seen also in the 

 European genera Dichobune and Cainotherium. There were four toes 

 on each foot, and the metapodial bones were distinct. The type spe- 



