692 THE POPULAR SCIENCE MONTHLY. 



ever, leaves the Old World Edentates, fossil and recent, unaccounted 

 for; but I believe the solution of this problem is essentially the same, 

 namely, a migration from North America. The Miocene representa- 

 tives of this group, which I have recently obtained in Oregon, are 

 older than any known in Europe, and, strangely enough, are more 

 like the latter and the existing African types than like any of our liv- 

 ing species. If, now, we bear in mind that an elevation of only 180 

 feet would close Behring's Straits, and give a road thirty miles wide 

 from America to Asia, we can easily see how this migration might 

 have taken place. That such a Tertiary bridge did exist, we have 

 much independent testimony, and the known facts all point to exten- 

 sive migrations of animals over it. 



The Cetacea are connected with the marine Carnivores through 

 the genus Zeuglodon, as Huxley has shown, and the points of resem- 

 blance are so marked that the affinity cannot be doubted. That the 

 connection was a direct one, however, is hardly probable, since the 

 diminutive brain, large number of simple teeth, and reduced limbs 

 in the whales, all indicate them to be an old type, which doubtless 

 branched off from the more primitive stock leading to the Carnivores. 

 Our American extinct Cetaceans, when carefully investigated, prom- 

 ise to throw much light upon the pedigree of these strange mammals. 

 As most of the known forms were probably marine, their distribution 

 is of little service in determining their origin. 



That the Sirenians are allied to the Ungulates is now generally 

 admitted by anatomists, and the separation of the existing species in 

 distant localities suggests that they are the remnants of an extensive 

 group, once widely distributed. The large number of teeth in some 

 forms, the reduced limbs, and other characters, point back to an an- 

 cestry near that of the earliest Ungulates. The gradual loss of teeth 

 in the specialized members of this group, and in the Cetaceans, is 

 quite parallel with the same change in Edentates, as well as in Ptero- 

 dactyles and Birds. 



The Ungulates are so distinct from other groups that they must be 

 one of the oldest natural divisions of mammals, and they probably 

 originated from some herbivorous marsupial. Their large size, and 

 great numbers, during Tertiary and Post-Tertiary time, render them 

 most valuable in tracing migrations induced by climate, as well as in 

 showing the changes of structure which such a contest for existence 

 may produce. 



In the review of the extinct Ungulates, I have endeavored to show 

 that quite a number of genera, usually supposed to belong originally 

 to the Old World, are in reality true American types. Among these 

 were the horse, rhinoceros, and tapir, all the existing odd-toed Ungu- 

 lates, and, besides these, the camel, pig, and deer. All these I believe, 

 and many others, went to Asia from our Northwest coast. It must, 

 for the present, remain an open question whether we may not fairly 



