74 CHIPPING SQUIRREL. 



snow-bird, Lapland long-spur, &c., which resort annually to them, 

 should, at that season, take wing and stray to either continent, is so proba- 

 ble a case, that we might think it strange if it were otherwise. Neither 

 need we regard it as singular if a few quadrupeds, with peculiar con- 

 stitutions and habits suited to the polar regions, should be inhabitants of 

 the northern portions of both continents. Thus, the polar bear which 

 delights in the snow and ice, and which is indifferent as to whether it 

 is on the land or on an iceberg at sea; the reindeer, which exists only in 

 cold regions, and which, by alternately swimming and walking, can make 

 its w^ay over the icy waters in winter, and over rivers and arms of the 

 sea in summer, and which migrates for thousands of miles ; the beaver, 

 which is found all over our continent ; on the banks of the Mackenzie 

 river, leading into the polar sea, in latitude 68°, and in the Russian settle- 

 ments near Behring's Straits ; the ermine, which riots in the snow-drifts, 

 and has been found as far to the north as man has ever travelled ; and 

 the common wolf, which is a cosmopolite, exhibits itself in all colours, 

 and strays from the tropics to the north pole, may be found on both con- 

 tinents, without surprising us : but if this little land animal, the Chipping 

 Squirrel, which is unable to swim, and retires to the earth in cold wea- 

 ther, should be found both in Asia and America, it would oppose all our 

 past experience in regard to American quadrupeds, and be the only ex- 

 ception to a long and universally admitted theory. The highest northern 

 range in which this species has ever been seen is above Lake Huron, 

 as far as latitude 50° ; from thence there is a distance of more than 

 90° of longitude and 18° of latitude, before we reach its Asiatic range, 

 and in its migrations either way it would have to cross Behring's Straits, 

 and traverse regions, which even in summer are covered with snow and 

 ice. From the above facts, and from our knowledge of the adaptation of 

 various animals for extensive migrations, we must conclude that this spe- 

 cies cannot possibly exist on both continents, even admitting the correct- 

 ness of the supposition, that these continents had in some former age been 

 united. 



Dr. RicHAKDsoN says, (p. 181,) "I am not aware that the identity of the 

 species on the two continents has been established by actual comparison." 

 In this he w^as quite correct. At the period at which his valuable work 

 on American quadrupeds was published, nearly all the figures, and many 

 of the descriptions of Tamias striatus of the Eastern continent, were taken 

 Irom American specimens of Tamias Lysieri ; and the authors supposing 

 them to be identical, were not sufficiently cautious to note this important 

 fact. 



In 1838 we carried to Europe, American specimens of nearly all those 



