288 PROCEEDINGS OF THE ACADEMY OF [1894. 



tains," and described minutely by Richardson (Fan. Bor. Amer. , 

 1829, 120), under caption of "Arvicola riparins (Ord?)," is almost 

 certainly a member of the genus Aidaeomijs.^ A comparison of the 

 description of this animal given by Richardson and that given by 

 Audul)on and Bachman,' when they renamed it A. richirdsoni, with 

 my type of Aviacomys arvicoloides, leaves very little room for doubt 

 that the two are generically the same. Their specific differences con- 

 sist in the much longer tail of arvlcololde><, its tail also being black 

 above and nearly unicolor, its feet black, and the mouth and chops 

 grayish-brown, like the surrounding parts. 



An examination of Richardson's introductory notice of Mr. 

 Drummond's travels, coupled with the statement that the specimen 

 was taken in summer, fix the type locality of A. richardtionl within, 

 say, fifty milffe of Athabasca Pass in the Rocky Mountains, among 

 the foothills traversed by the Columbia Portage trail connecting the 

 head waters of the Athabasca, Saskatchewan, and Columbia Rivers, 

 in latitude 53°. ^4. arvicoloides was taken somewhat east of the 

 dividing ridge of the Cascade Mountains in latitude 47°. Should 

 the correctness of this interpretation be proved, Drummond's speci- 

 men should stand as Axdacomys richardsonl (Dekay).** 



« Ehoads, Amer. Nat., Feb. 1894, 182. 

 ' Quad. N. Amer., Ill, 1853, 163. 

 s N. Y. Zool., I, 1842. 91. 



