32 



ISrORTH AMERICAN FAUl^A. 



[No. 36. 



Specimens examined. — Total number, 153, from tlie following locali- 

 ties: 



North. Dakota: EUendale, 2; Fort Clark, 4; Hankinson, 4; Ludden, 2; Oakes, 1. 

 South. Dakota: Clay County, 2. 

 Montana: Billings, 5; Fort Custer, 4. 



Wyoming: Arvada, 4; Casper, 1; Meadow, 1; Pole Creek, Laramie County, 1; 

 Splitrock, 3; Sun, 3. 



Colorado: Boulder, 1; Canon City, 5; Denver, 2; Golden, 2; Greeley, 1; Love- 

 land, 14; Valmont, 1. 



Kansas: Cloud County, 2;^ Lawrence, 9;^ Neosho Falls, 1; Onaga, 18; Pen- 

 dennis, 5. 



Nebraska: Alliance, 2; Beemer, 1; Callaway, 3; Cherry County, 1; 10 miles 

 south of Cody, 1; Columbus, 3; Ewing, 1; Glen, Sioux County, 1; Haigler, 

 2;^ Kearney, 2; Kennedy, 12; 18 miles northwest of Kennedy, 5; Neligh, 9; 

 Norfolk, 1; Two Mile Lake, Cherry Coimty, 1; Valentine, 2; Verdigris, 2. 



Iowa: Atlantic, 2; Hillsboro, 2; Palo Alto County, 1.* 



Missouri: St. Louis, 1; Thayer, 2. 



REITHRODONTOMYS MEGALOTIS NIGRESCENS subsp. nov. 

 Dusky Harvest Mouse. 



Type from Payette, Idaho. No. 201616, U. S. Nat. Mus., Biologi- 

 cal Survey Collection, c? adult, Jime 9, 1913; L. E. Wyman. Original 

 No. 98. 



Distribution. — Eastern Oregon and western Idaho; north to Fres- 

 co tt. Wash., south to Bieber, Cal. 



Characters. — Similar to megalotis, but upperparts more blackish and 

 less buffy; grayer and less ochraceous than longicaudus. 



Color. — Winter pelage: Upperparts mixed blackish and pale ochra- 

 ceous-buff, the black predominating on dorsal area; lateral line of 

 buff only faintly indicated ; ears hair-brown, clothed with ochraceous 

 hairs; tail blackish brown above, white below; feet and underparts 

 white. Summer pelage (July): General tone of upperparts more 

 brownish and less blackish than in winter pelage. 



Slcull. — Closely similar to that of megalotis, but with slightly longer 

 nasals. 



Measurements. — Average of 7 adults from Idaho : Total length, 144 

 (140-153); tail vertebrae, 68 (63-75); hind foot, 17 (16-18). Skull: 

 (See table, p. 81). 



Bemarlcs. — This race occupies the extreme northwestern part of the 

 range of the species, chiefly in a region of old lava beds where the soil 

 is richer and vegetation more abundant than in the more arid deserts 

 to the southward. It is most nearly related to megalotis, but probably 

 intergrades also with longicaudus. 



1 Collection Kansas Univ. Mus. 



2 Collection Am. Mus. Nat, Hist. 



3 Collection Univ. of Nebraska. 

 * Collection Univ. of Michigau. 



