VOL. XI, PP. 221-223 JULY 15, 1897 



PROCEEDINGS 



OF THE 



BIOLOGICAL SOCIETY OF WASHINGTON 



DESCRIPTIONS OF FIVE NEW RODENTS FROM THE 

 COAST REGION OF ALASKA. 



BY C. HART MERRIAM. 



Microtus sitkensis sp. nov. 



Type from Sitka, Alaska. No. 73839, J* ad. U. S. Nat. Mas., Biological 

 Survey Coll. Collected August 3, 1895, by C. P. Streator. Original No. 

 4745. 



General characters. Similar in color and general appearance to M. cali- 

 fornicus in corresponding pelage, but somewhat darker and more reddish 

 brown; belly washed with pale buffy fulvous ; ears smaller; tail rather 

 short, upper side black. Cranial and dental characters distinctive. 



Color. Upper parts uniform grizzled brown, not conspicuously lined 

 with black hairs, and with a distinct ' reddish, brown ' suffusion, espe 

 cially on rump and neck, which is probably peculiar to late summer 

 pelage; under parts plumbeous (without white), the belly washed with 

 ochraceous buff; tail sharply bicolor, black above, white beneath ; fore 

 and hind feet and ankles dusky. 



Cranial and dental characters. Skull long and narrow, very broad inter- 

 orbitally ; braincase rounded (not angular) ; interparietal subtriangular 

 and rather small ; zygomata not spreading ; audital bullse large and rather 

 elongated (not rounded) ; incisive foramina very narrow and slit like, 

 falling far short of molars; teeth as in subgenus Microtus; first lower 

 molar with 3 closed loops on inner side and 2 on outer side, the anterior 

 loop with no external and only 1 internal salient angle. 



Remarks. While externally Microtus sitkensis resembles M. calif ornicas, 

 its cranial characters place it in a different group, along with the small 

 M. kadiacensis. 



Measurements. Type specimen: total length, 155; tail vertebrae, 42; 

 hind foot, 23. Cranial measurements : basal length, 25 ; zygomatic breadth, 

 14; palatal length, 13 [to incisor] ; interorbital constriction, 4.2. 



51-BioL Soc. WASH., VOL. XI, 1897 (221) 



