*.M) MICROTII8. 



Arvicola operarius Nelson. 



I'roc. Biol. Soc. Wash., VIII, i>. 189, December 28, 1893. 



= Microtus operarius i Nrl.'^on) . See Trouessart, Catalogus ]\Iamiualiniii, p. 564, 

 1897. 



2*1 2 2- ^l<iii ii»(l skull. Adult. St. Michael, Alaska. November, 

 1879. ColliH-tod by E. W. Nelson. Orioinal nuni})or 122. Skin 

 catalogued June 11, 1881; skull, March ll>, ISSG. 



Skin well preserved, but poorly made up, and right fore leg missing. Skull 

 perfect, except coronoid of left half of inan<lil)lc ])n>kcn away, left bulla slightly 

 injured. 



Microtus miurus oreas Osgood. I5iological Survey collection. 



Troc. Biol. Soc. Wash., XX, pp. 61-62, April 18, 1907. 



148596. Skin and skull. Adult male. Head of Toklat River, Alaskan 

 Range, Alaska. August 8, 19()6. Collected by C. Sheldon. 

 Original mimber 47 (62S9x). 



Well-made skin in good condition; skull perfect, except for broken left audital 

 bulla and two slight perforations in brain case. 



Microtus pamirensis Miller. 



Proc. Acad. Nat. Sci. Phila., 1899, p. 287, August 9, 1899. 



62161. Skin and skull. Adult male. Tagdumbash, Pamir; altitude 

 12,000 feet. June 18, 1891. Collected l)y Dr. W. L. Abbott. 

 ' Catalogued May IG, 1895. 



Well-iuaile skin in good condition; skull with left pterygoid broken and hole 

 in right audi tiU bulla; otherwi.«e perfect. 



Arvicola pauperrima Cooper. 



Anier. Nat., 11, j). 5.S5, December, 1868. 



^Microtus pauperrimus (Cooper). See Miller, North Amer. P'auna, No. 12, p. 

 f)!, July 2:}, 1896. 



llVil '"^Ivin and skull". Adult male, "(6)." Great Plains of the 

 Columl)ia, near the Snake River, southwestern Wasliington. 

 October 9, 1860. Collected by Dr. J. G. Cooper. Original lunn- 

 ber 126. Skin catalogued October 15, 1872; skull, March 5, 1891. 



Skin in poor condition; parts about head and shoulders glued on to a I'otton 

 filling. PosU'rior upper parts good for color; all the feet present, also the tail. 

 Skull in fragments, viz: ( 1 ) The premaxilhe and niaxilhe all in one piece, con- 

 taining all the upper jaw teeth except the last right and left upper molars; (2) 

 the interparietal with attached portions of the parietals; (3) a small ])iece of the 

 left squamosal; (4) the hori/ontiil i>arts of each lialf of the mandible containing 

 all the lower jaw teeth, of which the left incisor is broken at tlie cutting edge. 



Type designated by the original number. 



