Vol. XI, pp. 221-223 July 15, 1897 



PROCEEDINGS 



OF THR 



BIOLOGICAL SOCIETY OF WASHINGTON 

 t^ 



DESCRIPTIONS OF FIVE NEW RODENTS FROM THE 

 COAST REGION OF ALASKA. 



BY C. HART MERRIAM. 



Microtus sitkensis sp. nov. 



Tiji)c from Sitka, Alaska. No. 73S;>9, cJ'ad. U. S. Xat. Mas., Biological 

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

 4745. 



General cluiraders. — Similar in color and general ai)pearance to M. cali- 

 fornicns in corresponding pelage, but somewiiat darker and more reddish 

 brown; bell}' washed with pale buffj^ fulvous ; ears smaller; tail rather 

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



CVo;-. — Ui)per parts uniform grizzled brown, not conspicuously lined 

 Avith black hairs, and with a distinct ' reddish brown ' suti'usion, espe- 

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

 pelage; under parts plumbeous (without white), the bell}' washed with 

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

 and hind feet and ankles dusky. 



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

 orbitally; braincase rounded (not angular); interparietal subtriangular 

 and rather small ; zygomata not spreading ; audital bulhe 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 sitken,sis resembles M. calif ornicus, 

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

 J/, kadiacensis. 



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

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

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



51-Bioi. Soc. Wash., Vol. XI, 1897 (221) 



