THE PLEISTOCENE OR GLACIAL PERIOD. 497 



improbably its range also was shifted with the glacial movements; 

 but as it emigrated to South America and crossed the tropics, it can- 

 not have been ill-adapted to a warm climate, as perhaps the mam- 

 moth was. The mastodon likewise lived through the glacial period, 

 and is found in post-glacial deposits in middle latitudes. Williston 

 is authority for the suggestive fact that, while mammoths were very 



Fig. 565. — An interpretation of Mastodon americanus by G. M. Gleeson. 

 (From painting in National Museum, Washington.) 



abundant in Kansas and in the open plains where forests seem not to 

 have prevailed in Pleistocene times, the mastodon was almost exclu- 

 sively confined to the valleys and timbered regions, notably those 

 of the Eastern States, the Mississippi valley, and the foot-hills and shores 

 of the Pacific Coast. The mastodon has never been found on the 

 plains of Kansas, and the mammoth seldom in the formerly wooded 

 valleys. This calls in question the prevalent view that the presence 

 of the mammoth necessarily implied arboreous vegetation. Arboreous 

 vegetation, however, — of the minor type at least, — was present as 

 far west as Iowa and Dakota in some of the interglacial intervals. 



