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—16S. 
