MICROTUS. 189 



different. Anterior end of frontal narrow and without a lachrymal 

 tubercle. 



Color. Above 3'ellowish brown, darkest in middle of back and 

 lined sparsely with black; sides paler yellowish brown; beneath 

 plumbeous washed with wliite, with buff space on breast. Feet and 

 legs dark brownish. Tail, dusky above, white beneath. 



Measurements. Total length. Type, 188; tail vertebra;, 43; 

 hind foot, 22. "Average of three topotypes, 165, 38, 22.4." 



276. sitkensis. {Microtiis), Merr. , Proc. Biol. Soc. Wash., 1897, 



p. 221. 



Type locality. Sitka, Alaska. 



Geogr. Distr. Baranof Island, Alaska. 



Genl. Char. Size equal to M. unalascensis; tail short; skull 

 long and narrow; brain case rounded; audital bulla large, elongated; 

 incisive foramina narrow, not reaching molars; first lower molar with 

 three internal closed loops, and two external, the anterior loop with 

 one internal salient angle, and no external. Third lower molar has 

 four inner and four outer salient angles, and three closed triangles. 



Color. Above grizzled brown suffused with reddish brown; 

 brightest on rump, beneath plumbeous washed with ochraceous buff. 

 Tail, above black, below white. Feet dusky. 



.\[easiirements. Total length, 155; tail vertebrae, 42; hind foot, 

 23. Skull: basal length, 25; zygomatic breadth, 14; palatal length, 

 13; interorbital constriction, 4.2. 



277. innuitus. [Microtus), Merr., Proc. Wash. Acad. Scien., 1900, 



p. 21. 



Type locality. St. Lawrence Island, Bering Sea. 



Genl. Char. Skull and parts of skeleton alone known; ''cranium 

 large; zygomata heavy, bowed outward, anterior roots standing out- 

 ward and forward when seen from above; jugals slightly expanded; 

 brain case squarely truncate anteriorly; nasals large, cuneate; ros- 

 trum massive, prominent lip at border of anteorbital foramen; audital 

 bullae large; incisors produced and protruding. Hind molar with three 

 closed triangles; first molar with four, two on a side." 



Measurements. " Tail vertebrae, 43-45; hind foot, 22-24. Skull: 

 basal length, 32.5; zygomatic breadth, 19.5; mastoid breadth, 15.5; 

 nasals, 9; molar series, 7.2." (Merr., 1. c.) 



278. abbreviatus. {Microtus), Miller, Proc. Biol. Soc. Wash., 1899, 



P- 13- 

 Type locality. Hall Island, Bering Sea. 

 Geogr. Distr. Only known from type locality. 



