PLEISTOCENE OF EUROPE, NORTH AFRICA, AND NORTH AMERICA 419 



The giant fallow deer is found in Ireland, England, Scotland, the Isle 

 of Man, France, Denmark, Germany, Austria, northern Italy, and Eurasia, 

 even in Siberia. 



Migration. — The crowding out of the tundra fauna occurred in the follow- 

 ing manner.^ The great alpine glaciers still extended far out over the land 

 during the formation of the lower rodent layer. As these retreated they 

 left desolate stretches behind them and the valleys and plateaux now free 

 from ice became tundras, where swamps alternated with patches of polar 

 willows and stunted fir trees and places covered merely with low scrubby 

 birches or reindeer moss and lichens. As this vegetation retreated north 

 and south before the advance of the steppe climate, the tundra fauna fol- 

 lowed, the forms that moved south being confined to ever smaller areas and 

 higher altitudes. Enormous intervals of time elapsed between the deposi- 

 tion of the (3) yellow culture layer of the reindeer age and the (5) gray 

 culture layer of Neolithic times and the forest fauna. It was a slow change 

 that drove the steppe mammals gradually toward the dry regions of the 

 ea'st to make room for the forests and their faunas. It is clear that the 

 north and the east were the only directions open to them in their retreat 

 before the increasingly damp climate and the spread of woodlands. The 

 typical central European forest forms, the wild cat, marten, bear, hare, 

 roe, stag, and urus, which constituted the principal fauna of the succeeding 

 stage and of all later, prehistoric, 'and early historic time, was probably in 

 existence long before, but confined to small and scattered bits of forests on 

 mountain slopes and in gullies. The mterval between these yellow and gray 

 culture layers in human history means the change from the Pateolithic 

 reindeer stage to the Neolithic stage, because in the 'gray culture' layer 

 we find weapons and implements of polished stone which represent a stage 

 of culture similar to that of the Swiss lake dwellings. 



Mammals of the Third Faunal Zone 



Mammoths. — The mammoth {E. -primigenius) now reaches the height 

 of its evolution and specialization. As preserved in the frozen tundras of 

 northern Siberia it is the most completely knoAvn of all fossil Mammalia, 

 with its undercoat of wool and overcoat of long hair. As recently de- 

 scribed by Salensky - from the wonderfully complete specimen discovered 

 in 1901 on the banks of the Beresowka River in northeastern Siberia, this 

 animal developed characters which absolutely exclude the possibilitj^ of 

 its ancestry to the existing Indian elephants. The hind foot is four- 

 toed, or tetradactyl, and not five-toed as in the living forms. The head 



1 Studer, T., Die Tierreste aus don pleistocaenen Ablagerungen des Schweizershildcs bei 

 Schaffhausen. Neue Denkschr. allg. schweiz. Ges. gesam. Natunviss., Vol. XXXV, 1896, pp. l-'.iH. 



2 Salensky, W., Uber die Hauptresultate der ErforschunR dcs im Jahro 1901 am Ufcr der 

 Beresowka entdeckton niiuinlichen Mammutcadavers. C.R. Sea. Six. Congr. Internal. Zool. 

 Berne, 1904, pp. 67-86. 



