51 



the Camel, Pig, and Deer. All these I believe, and many 

 others, went to Asia from our North West Coast. It must, for 

 the present, remain an open question whether we may not 

 fairly elaim the Bovidce, 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 deposits called Upper Miocene, and 

 so rich in Proboscideans, 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 

 deposits in Greece, also regarded as Miocene. Believing, how- 

 ever, 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 relation- 

 ship 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 

 Proboscideans is a striking fact, not yet explained by the im- 

 perfectly 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 Machaii-odus, the saber-toothed 

 Tiger, which flourished in our Miocene and Pliocene, and 

 followed the huge Edentates to South America, and the Ungu- 

 lates across Asia to Europe. With this genus went Hycenodo?i, 

 and some typical Wolves and Cats, but the Bears came the 

 other way with the Antelopes. That the Gazelle, Giraffe, Hip- 

 popotamus, Hyaena and other African types, once abundant in 

 Asia, did not come, is doubtless because the Miocene bridge 

 was submerged before they reached it. 



