1914.] 



BEITHKODONTOMYS HUMULIS GEOUP. 



23 



Kennedy and Neligh, Nebr., it has been taken in the same weed 

 patches with B. megalotis dychei. It may be distinguished from the 

 latter by its smaller size, paler and less ochraceous coloration, and 

 small ears with distinct black spots. 



Although closely resembling montanus in color, it differs consider- 

 ably from it in cranial characters, and no evidence of intergradation 

 between the two species has been obtained. In southern Nebraska 

 it grades into the subspecies griseus. 



Specimens examined. — Total number, 25, from the following locali- 

 ties: 



Nebraska: Kennedy,!; 18 miles northwest of Kennedy, 4; Neligh, 8; Niobrara, 



1; Niobrara River, 10 miles south of Cody, 2; Verdigris, 4. 

 South. Dakota: Belle Fourche River (15 miles from mouth), 1. 

 Colorado: Loveland, 4.^ 



REITHRODONTOMYS ALBESCENS GRISEUS Bailey. 

 Little Gray Harvest Mouse. 

 (PI. I, fig. 3; PI. IV, fig. 3.) 



Reithrodontomys dychei Allen, Bull. Am. Mus. Nat. Hist., VIII, 1896, p. 67 (not of 

 I VII, 1895, p. 120). 



I Reithrodontomys griseus Bailey, N. Am. Fauna No. 25, 1905, p. 106. 

 Type locality. — San Antonio, Tex. 



Distrihution. — Southern Nebraska, Kansas, Oklahoma, central and 

 western Texas, and eastern New Mexico. Limits of range imper- 

 fectly known. 



Characters. — Similar to albescens but colors darker and skull 

 narrower; much paler and grayer than merriami. 



Color. — ^Upper parts mixed black and light ochraceous-buff, the 

 black predominating and usually forming an indistinct stripe along 

 I the median line; lateral line of buff very faintly indicated; buff on 

 1 sides of head darker than in montanus; ears same color as back, 

 I usually with a large blackish patch on exterior surface; tail sharply 

 ! bicolor, hair-brown above, grayish white below. 



STcuU. — Similar to that of albescens, but zygomata weaker and less 

 widely expanded and rostrum narrower. Compared with merriami: 

 Braincase less elongated; rostrum slenderer; zygomata more widely 

 expanded posteriorly; interpterygoid fossa averaging narrower; 

 j bullae less elongated. Compared with montanus: Braincase shorter 

 i and relatively broader, with shorter rostrum; zygomata more 

 contracted anteriorly. 



Measurements. — ^Average of 9 specimens (mostly immature) from 

 type locahty: Total length, 115 (107-120); tail vertebrae, 54 (48-61); 

 hind foot, 14.6 (14-16).^ Average of 2 adults from Clyde and San 



1 Collection of G. S. Miller, jr. 



2 The total length is probably less than in adult specimens and the foot measurements are apparently 

 smaller in some cases than they should be. 



