Mar. 1898. NORTH AMERICAN MAMMALS ELLIOT. 205 



i, Echo, Eldorado Co.; 19, Hermit Valley, Calaveras Co.; i, 

 Edgewood, Douglas Co., Nevada. I compared these specimens 

 with a number kindly sent to me by Dr. Merriam, of his Arvicola 

 mordax from Idaho and other localities. My examples were all 

 taken in June, July and August, and are therefore in the majority 

 of cases in a different pelage from his specimens taken mostly 

 later in the year. All are gray or grayish on the rump, making 

 them very conspicuous when laid side by side. Dr. Merriam, in 

 his description of the type (1. c.), does not mention this colora- 

 tion, and I should have been inclined to consider these examples 

 as representing a race of his species, as their localities are 

 rather widely separated, were it not that among his specimens I 

 found one that agreed with these in this particular and which 

 was procured in the same month. It would appear, then, that 

 the summer pelage is characterized by a decidedly gray rump, this 

 color extending onto the thighs and hind legs. The skulls of 

 these and Dr. Merriam's specimens presented no differences. 



Measurements of seventeen examples give maximum total 

 length, 202 mm. ; mimimum, 171. Tail, maximum, 72; minimum, 

 56. Hind leg, maximum, 24; minimum, 20. 



28. Microtus curtatus. 



Microtus curtatus. Cope, Proc. Acad. Nat. Scien., Phila., 

 1868, p. 2. 



Three specimens from Mt. Siegel, Douglas Co., Nev., one of 



which is absolutely pure white. This would seem to be either a 



rare species in this locality, or the collector had poor luck in 



trapping it, as only three examples were procured out of the 



* great number of animals obtained at Mt. Siegel. 



29. Peromyscus californicus. 



Arvicola californica. Peale, Mam. and Birds, U. S. Expl. 

 Exp., 1848, p. 46. 



Four hundred and fifty-six specimens from the following local- 

 ities : Portola, San Mateo Co., 240; Alum Rock Park, Santa 

 Clara Co., 176; Mt. Hamilton, Santa Clara Co., 20; Carmel 

 River, Monterey Co., 15. 



The examples in this large series were taken from December 

 to July, and the color of the pelage varies according to the 

 season, those from December to April being very dark, almost 

 black above, and from thence onward to July, changing to gray 

 or pale rufous, interspersed with black or brownish-black, 



