VERTEBRATE LIFE IN AMERICA. 693 



claim the Bovidoe, and even the Proboscidea, since both occur in our 

 strata at about the same horizon as on the other continent. On this 

 point there is some confusion, at least in names. The Himalayan de- 

 posits called upper Miocene, and so rich in Proboscidians, indicate 

 in their entire fauna that they are more recent than our Niobrara River 

 beds, which, for apparently good reasons, we regard as lower Pliocene. 

 The latter appear to be about the same horizon as the Pikermi de- 

 posits in Greece, also regarded as Miocene. Believing, however, that 

 we have here a more complete Tertiary series, and a better standard 

 for comparison of faunas, I have preferred to retain the names already 

 applied to our divisions, until the strata of the two continents are 

 more satisfactorily coordinated. 



The extinct Rodents, Bats, and Insectivores of America, although 

 offering many suggestive hints as to their relationship with other 

 groups, and their various migrations, cannot now be fully discussed. 

 There is little doubt, however, that the Rodents are a New World 

 type, and, according to present evidence, they probably had their 

 origin in North America. The resemblance in so many respects of 

 this order to the Proboscidians is a striking fact, not yet explained 

 by the imperfectly known genealogy of either group. 



The Carnivores, too, I must pass by, except to call attention to a 

 few special forms which accompanied the migrations of other groups. 

 One of these is Machairodus, the sabre-toothed tiger, which flourished 

 in our Miocene and Pliocene, and apparently followed the huge Eden- 

 tates to South America, and the Ungulates across Asia to Europe. 

 With this genus went Hyamodon, and some typical wolves and cats, 

 but the bears probably came the other way with the antelopes. That 

 the gazelle, giraffe, hippopotamus, hyena, and other African types, 

 once abundant in Asia, did not come, is doubtless because the Mio- 

 cene bridge was submerged before they reached it. 



The Edentates, in their southern migration, were probably accom- 

 panied by the horse, tapir, and rhinoceros, although no remains of the 

 last have yet been found south of Mexico. The mastodon, elephant, 

 llama, deer, peccary, and other mammals, followed the same path. 

 Why the mastodon, elephant, rhinoceros, and especially the horse, 

 should have been selected with the huge Edentates for extinction, and 

 the other Ungulates left, is at present a mystery, which their some- 

 what larger size hardly explains. 



The relations of the American Primates, extinct and recent, to 

 those of the other hemisphere, offer an inviting topic, but it is not with- 

 in my present province to discuss them in their most suggestive phases. 

 As we have here the oldest and most generalized members of the 

 group, so far as now known, we may justly claim America for the 

 birthplace of the order. That the development did not continue here 

 until it culminated in man, was due to causes which at present we can 

 only surmise, although the genealogy of other surviving groups gives 



