PLEISTOCENE OF EUROPE, NORTH AFRICA, AND NORTH AMERICA 417 



the tlieoiy of Richthofcn, owes its origin to wind-borne dust and sand acting 

 under the influence of a dry, steppe chniate both in summer and winter. 

 However, Kobelt^ and Scharff - (1899, p. 212) agree in thinking that the 

 presence of steppe mammals affords no proof of the steppe^ character of th(>i 

 country. 



The steppe regions of northern Asia still maintain this fauna. Such 

 animals as the j(>rboa, which are unable to swim, presumably crossed the 

 rivers while these were frozen over. The absence of fossil plants in the 

 deposits of the steppe period is due to the unfavorable conditions for the pres- 

 ervation of plant remains. Small stretches of woodland were probably 

 confined to the banks of rivers, to favorable mountain slopes, etc. The 

 flora was probably like that of eastern Eurasia or southwestern Siberia 

 to-day. 



The fauna included, beside the jerboa, the rufous sizel, or suslik (Sper- 

 mophilus rufescens), the bobac marmot (Marmota bobac), the dwarf pica, 

 the hamsters, the northern voles, the corsac fox {Canis corsac), the manul, 

 or Pallas's cat (Felis manul). Covering the plains were the larger grazing 

 animals such as the saiga antelope, the wild asses (dzeggetai), and the wild 

 horses, probably similar to the still surviving Equus przewalskii. Ewart con- 

 siders it probable that the Celtic pony (E. caballus celticus) also came with 

 the steppe fauna, while the yellow dun, ''Norse" horse, or forest typo, 

 belongs to the succeeding forest fauna. There is evidence of ' steppe blood ' 

 in the horses of the Pleistocene deposits of the Rhine valley and in the 

 horses of the Palaeolithic drawings of the Magdalenian caves, while there 

 is evidence of 'Celtic blood' in the horses of the mammoth beds of Britain. 



The saiga antelope has now retreated to the steppes of eastern Europe 

 and western Siberia. The jerboa (Aladaga jaculus) is now confined to 

 Eurasia and western Siberia. The bobac marmot {Marmota bobac) has a 

 similar range. 



The characteristic fauna of the modern Alps is mainly of central Asiatic 

 rather than of Siberian origin.^ 



Forest fauna. — Following the retreat of the glacial cap and the grad- 

 ual depression of northern Europe came a more humid climate, favorable 

 for reforestation. Besides the common squirrel (Sciurus vulgaris), the 

 herald of forest conditions all over the northern hemisphere, there appeared 

 the red deer, the roe deer, the moose, the wild boar, the red fox, the badger, 

 the wolverine, the pine marten, the pole cat {Fa>torius putorius), the ermine, 

 and the common weasel (Mustela vulgaris).* 



With these still living species were mingled the great extinct mammals 

 of the times, and occasionally these three great faunas are found pure, or 



1 Kobclt, W., Die Vorbrcitung der Tierwelt. Gemilssigte Zone. Leipzig, 1902. 



2 Scharff, R. F., The History of the European Fauna. London, 1S99. 

 •■'Scharff, R., The History of the European Fauna. London, 1S99 (p. 340). 



* Kobelt, W., Die Verbreitung der Tierwelt. Gemiissigte Zone. Leipzig, 1902. 

 2 E 



