364 PROCEEDINGS OF THE ACADEMY OF [1898. 



by its bright color, absence of any known dusky phase, relatively 

 long tail, and small square skull with large audital bulla?, conspicu- 

 ous rostral protuberances, and short nasal bones. 



Evotomys alascensis sp. nov. 



1S39. ?? Arvicola rubricatus Richardson, Zoology of Beechey's Voyage of 



the Blossom, p. 7 (Bering Strait). 

 1877. Evotomys rutilus Coues, Monogr. N. Am. Rodentia, p. 136 (part). 

 1897. Evotomys rutilus Bailey> Proc Biolog. Soc Washington, XI, p. 118 



(part). 



Type. — Adult S , number ^l United States National Museum, 

 collected at St. Michael's, Alaska, October 26, 1897, by E. W. Nel- 

 son. Original number, 96. 



General characters. — See synopsis, page 359. 



Skull. — The skull of Evotomys alascensis more closely resembles 

 that of E. rutilus than it does that of its geographically nearer ally 

 E. wosnessenskii. The brain case is broad and squarish in outline. 

 Squamosals produced into very small, pointed postorbital processes. 

 Audital bullae large, their greatest breadth considerably more than 

 alveolar length of maxillary molar series. Rostral protuberances 

 (fig. 1 b) much closer to roots of zygomata than in either of the Old 

 World species. The nasal bones (fig. 1) are longer than in either 

 E. rutilus or E. wosnessenskii. This difference is not due to greater 

 length of rostrum, but to greater backward prolongation of the nasal 

 bones. The nasal branches of the premaxillaries also extend fur- 

 ther back than in either of the Old World forms. 



The skull of the type specimen measures : greatest length, 25 mm ; 

 basal length 22.6; basilar length, 21.8 ; zygomatic breadth, 13.4 ; 

 mastoid breadth, 11.6 ; interorbital constriction, 4.6 ; nasals, 8 ; in- 

 cisive foramen, 5 ; diastema, 7 ; maxillary molar series (alveoli), 

 5.2 ; mandible, 14 ; mandibular molar series (alveoli), 5. 



Teeth. — The enamel pattern (fig. 2 c) is essentially as in Old 

 World Arctic species. 



Ears. — The ears do not differ in form from those of E. rutilus and 

 E. wosnessenskii, but they are appreciably larger than in the lat- 

 ter. 



Feet. — The front feet present no characters of importance. The 

 hind feet, like those of E. rutilus, are short, broad, and very densely 

 haired both above, on the sides, and below. On the sole the hair 

 extends from the heel to the middle row of tubercles. 



Color. — In the type the dorsal stripe is dull ferruginous sprinkled 

 with black hairs, which, however, are very inconspicuous. Sides 



