1898.] NATURAL SCIENCES OF PHILADELPHIA. 359 



Even if it be assumed, as Baird has suggested, 3 that the colors of 

 the back aud sides were accidentally transposed in Richardson's 

 description, the case is not much helped, since no known member of 

 the rutilus group has slate colored sides. Although Baird assumed 

 that Richardson's animal came from Siberia, the statement in the 

 original description that it " appears to be quite distinct from any 

 American meadow mouse hitherto described," leads to the belief 

 that the type locality was on the Alaskan side of the strait. The 

 objections to applying the name to the Alaskan animal are, how- 

 ever, no less than in the case of the Kamtschatkan species. 



The general characters of Evotomys rufocanus, and of the three 

 species hitherto confused under the name rutilus, are given in the 

 following synopsis : 



Teeth large and heavy as in Microtus (never perfectly rooted ?) ; 

 molar rows about 6.5 mm. ; posterior lower molar long, some- 

 what encapsulated ; skull with prominent postorbital processes ; 



sides clear gray (highly aberrant) E. rufocanus. 



Teeth small and weak (perfectly rooted in adult) ; molar rows 

 about 5 mm. ; posterior lower molar short, not encapsulated ; 

 skull without prominent postorbital processes; sides strongly 

 fulvous (typical Evotomys). 



Skull narrow ; rostral protuberances standing out conspicu- 

 ously from root of zygoma (fig. 1 a) ; audital bulla? small ; 



feet slender E. wosnessenskii. 



Skull broad ; rostral protuberances not standing out con- 

 spicuously from root of zygoma (fig. 1 b) ; audital bulla? 

 large ; feet broad. 



Nasal bones short, contained 3* times in greatest length 

 of skull ; tail 34-40 mm. ; color generally chestnut 



E. rutilus. 



Nasal bones long, contained only 3 times in greatest 



length of skull ; tail 20-30 mm. ; color generally dull 



ferruginous E. alascensis. 



Evotomys rufocanus (Sundevall). 



1846. Arvicola rufocanus Sundevall, Oefv. Vet. Akad. Foerh., p. 122. 

 1897. Evotomys rufocanus Bailev, Proc. Biolog. Soc. Washington, XI, p. 

 122, May 13, 1897. 



Skull. — The only skull of Evotomys rufocanus that I have at hand 

 is badly damaged. Nevertheless it shows strong characters to dis- 



s Mam. N. Am., p. 551. 



