THE HARRIMAN ALASKA EXPEDITION 2$ 



Measuremefi^s.— Type: total length 138; tail vertebrai 30; hind 

 loot 20. Average of 6 specimens from type locality : total length 

 140; tail vertebra; 32; hind foot 20. 



JiemarJts.— The coloration varies somewhat, and the differences 

 are probably seasonal. The type, which appears to be in fresh sum- 

 mer pelage, is in the darkest stage. Other specimens, apparently in 

 left-over winter pelage, or in the molt, are paler, but still have the 

 characteristic dark feet and tail. In 6 out of the 7 specimens secured 

 by us in Prince William Sound, the underparts are strongly suffused 

 with buffy ochraceous; in one only they are whitish (no. 98035). 



DICROSTONYX UNALASCENSIS sp. nov. 



Unalaska Lemming. 



Type from Unalaska, Alaska. No. 99622 ad. U. S. National 



Museum, Biological Survey Collection. July 8, 1899. C. Hart 



Merriam. Found in owl pellets. 



C/iaracters.—S\ze rather large, equalling or exceeding B. Jmd- 

 sotihts from Labrador; external characters unknown. Skull large 

 and broad with subquadrate braincase, broadly spreading rounded 

 zygomata, broadly sulcate frontal, and prominent peg-like postorbital 

 processes of squamosal. 



Compared with D. hudsonius from Chimo, Ungava, the anterior 

 angle of the zygoma is less expanded, jugal longer, angle of mandible 

 broader and more strongly everted, bulla; much larger; upper in- 

 cisors much broader; ;«i with 3 (instead of 2) closed triangles on 

 inner side in addition to posterior (or heel) loop; m'^ with 2d loop 

 on inner side normal and separated by full interspace from anterior 

 crescent of w^, and with posterior (heel) loop on outer side com- 

 plete. In Jmdsonms the 2d loop on inner side is narrowed or flat- 

 tened and in contact with m^, and the posterior loop on outer side is 

 absent or reduced to a small remnant. 



DICROSTONYX NELSONI sp. nov. White Tundra Lemming. 



Type from St. Michaels, Alaska. No. f|ff 9 yg. ad. Merriam 



Collection. 



Characters.— '^'xT.e rather small; a dark dorsal stripe present in 

 summer pelage; winter pelage white. 



Color.— Type specimen in change from winter to summer pelage 

 (date unknown) : Upperparts from halfway between nose and eyes 

 to rump finely mixed chestnut and yellowish white (hairs with chest- 

 nut tips and a broad subapical zone of yellowish or buffy) becoming 



