498 GEOLOGY. 



Several species of horses have been found in western beds referred 

 to the Pleistocene period. A gigantic elk ranged from Mississippi at 

 least as far northeast as New York, and in the interior as far north 

 as Kansas. Two or three species of buffaloes roamed over the Ohio 

 valley, and southward to the Gulf. The musk-ox (Ovibos), a thoroughly 

 arctic animal, now living on the very borders of the ice-fields, has 

 been found as far south as Virginia and Kentucky, as has also the 

 reindeer. A large saber-toothed cat mingled its remains with those 

 of Elephas in Oklahoma. The beaver-like Casteroides ohioensis is 

 known to have ranged from Ohio and New York, south to Missis- 

 sippi. Bears, rather recent emigrants from Eurasia, were present, 

 as were also wolves, peccaries, and the vanishing group mentioned 

 above. 



The southern group. — Over against this assemblage of more or less 

 boreal forms that were pushed southward by glacial advances, there 

 was the group of South American immigrants, the monster sloths, 

 Megatherium, Mylodon, Megalonyx, and the gigantic armadillo, Glyp- 

 todon, the last covered by a strong carapace of sculptured ossicles, 

 and armed with a massive tail plated with spiked ossicles. The remains 

 of this group have been found chiefly in caverns and crevices, or in 

 the muck and mire about salt springs, or in fluvial deposits, the pre- 

 cise ages of which are difficult to fix, and it ought not to be very firmly 

 concluded that they were present during the glacial period, until their 

 remains are found in interglacial beds, or in demonstrable equivalents 

 of the glacial series. There is apparently nothing, however, in the 

 climatic conditions of such an interglacial stage as that which per- 

 mitted pawpaws and osage oranges to flourish about Toronto, to for- 

 bid their presence in the most northerly ranges in which their relics 

 are found, Pennsylvania and Oregon. Whether they could have held 

 their ground in North America when the ice-sheet reached southern 

 Illinois, is more problematical. 



The European Pleistocene Life. 



Oscillatory migrations. — A complete agreement as to the migra- 

 tions of faunas and floras in Europe during the glacial period is yet to 

 be reached, but the data have been sufficiently developed to justify 

 the tentative attempts that have been made to trace the oscillations 



