MAMMOTHS IN ALASKA 87 



discovered in an undoubtedly pre-Glacial deposit at Troizkoje, 

 near Moscow. 



In Alaska the mammoth is the only elephant that has been 

 found fossil. In the United States its remains are associated 

 with those of two other elephants, viz., Elephas columbi and 

 Elephas imperator, which, according to Professor Osborn,* 

 are analogous to the European Elephas antiquus, and E. 

 meridionalis. The ranges of these species overlap, yet their 

 distribution seems to imply that the mammoth was the last- 

 comer, or that it became modified in structure further south, 

 giving rise to the two other species of elephants. The de- 

 posits in which the mammoth occurs in the United States 

 are generally looked upon as Pleistocene. But in the Potter 

 Creek Cave in California it is associated with Mastodon, 

 Megalonyx and other types belonging to extinct genera.f 

 This cave contains nearly fifty per cent, of extinct species, 

 and if situated in Europe would probably be classed among 

 Pliocene deposits. 



Similar cases illustrating the invasion of Asiatic types by 

 way of Alaska, and their apparent modification in character 

 as they travelled southward, occur in almost all groups of 

 animals. Sometimes, however, we meet with' instances that are 

 very difficult to explain by the assumption of their ancestors 

 having utilised the land bridge alluded to. The magpie (Pica 

 rustica), for example, is a handsome and strikingly coloured 

 bird inhabiting the whole of Europe, North Africa, central 

 and eastern Asia and western North America. Various races 

 and varieties are recognisable among the Asiatic magpies, 

 while the north African form is likewise distinct. Curiously 

 enough, the American variety resembles the European form 

 more closely than it does any of the Asiatic ones, and it occurs 

 from Alaska to Mexico, and eastward as far as the Missouri 

 River, whereas no magpies at all have been noticed in the 

 extreme north-east corner of Asia. The distribution is there- 

 fore somewhat discontinuous, the most easterly district in 

 Asia where it is known being southern Kamchatka. In the 

 extreme south-west of its American range in southern 



* Osborn, H. F., "Mammalian Palaeontology," p. 111. 

 t Brown, Barnum, " Conard Fissure," pp. 167 168. 



