MUSEUM OF COMPARATIVE ZOOLOGY. 225 



his Mammals of North America (p. 289), but remarks that, from insufficient 

 data, he was unable to arrive at a definite conclusion as to whether 

 it was really distinct from P. hudsonius. The P. oregonensis of Bachman 

 seems also very doubtfully distinct from P. rolucdla, as it does not differ 

 very appreciably from the Eastern animal. The following remarks from 

 Audubon and Bachman's North American Quadrupeds* in respect to 

 the number of species of North American Pteromys are very suggestive. 

 " As long," they observe, " as only two species of flying squirrel were 

 known in North America, — the present species (P. scibrinus) and the little 

 P. volucella, — there was no difficulty in deciding on the species, but since 

 others have been described in the far West, the task of separating and 

 defining them has become very perplexing." 



Specimens in the Museum of Comparative Zoology from Lake Superior, 

 Northern Maine, New Hampshire, Massachusetts, and the Middle States, 

 form a graduated series in size, the first-mentioned, or northern, corre- 

 ponding with the P. " sabririus" ; the southern, of course, with the true P. 

 volucella of authors. Difference in size has been the only appreciable char- 

 acter that has been advanced as distinguishing them. 



55. Tamias striatus Baird. (T. americanus Kuhl. Sciurus 

 striatus Klein, Emmons's Rep., p. 68.) Striped Squirrel. Chip- 

 munk. Abundant. Usually first seen abroad in spring towards the close 

 of March, when they are readily detected by their loud clucking note. 



A series of nearly fifty specimens in the Museum of Comparative Zo- 

 ology, from various localities in Eastern Massachusetts, are extremely uni- 

 form in color, the variations being so slight as to be scarcely appreciable. 

 A considerable number of others, from different localities in Maine, are 

 generally very much lighter or paler colored. These, also, vary a good 

 deal among themselves, chiefly, however, in the character of the stripes, 

 which in several specimens are much less distinct than usual. In one they 

 are quite faint and irregular, the light central one on the sides being alone 

 well defined, and this is at one point interrupted. The difference in gen- 

 eral tint between these Massachusetts and Maine specimens is quite marked 

 in the rufous-colored regions of the animal, and especially on the posterior 

 part of the back. 



56. Arctomys monax Gmelin. Woodchuck. Abundant. At 

 Springfield a number of specimens of the black variety have been taken 

 within the last few years, and also three albinos. One of these is nearly 

 white (pale grayish-white), and the other two are pale yellowish-brown 



* Vol. Ill, p. 205. 

 29 



