208 



BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



EVOTOMYS KUTILUS GAPPERI, (Vig.) Coues. 



The ordinary Eed-backed Mouse is very abundant in this vicinity. 

 The characteristic red marking of this Mouse is attained very early, for 

 I have observed it in the young of all ages. 



The nest of this Mouse in this vicinity is usually constructed on the 

 ground, under a large bowlder, or sometimes under an old log or wood- 

 pile, and is sparingly lined with grass or other suitable substances. 



The young, of which there are from three to eight, are brought forth 

 as early in May as the 3d, and I have also seen them as late as September 

 30th, from which I would infer that there are at least two litters brought 

 out each year. 



The measurements of the specimens taken are as follows : — 



Arvicola (Myonomes) riparius, Ord. 



[Doubtless common in Dr. McChesney's locality. See bracketed remarks under next 

 head. On calling the author's attention to this point, I am favored with the following 

 reply :— 



" October 22, 1877.— In ten specimens of Arvicolw examined to-day, the U-,V-, or Y- 

 shaped trefoil of the back upper molar is present in all but one; and no doubt, as yoa 

 suggest, my list contains measurements of both riparius and austerus." — E. C] 



Arvicola (Pedomys) austerus, LeConte. 



The Prairie Meadow Mouse is very common in this vicinity, provided 

 I am right in referring all my specimens of the genus Arvicola to this 

 species. Examination of the molars of several specimens has been at- 

 tended with nearly uniform reference to A. austerus ; and I, therefore, 

 believe that A. riparius is found here only in small numbers. 



I have observed this Mouse breeding here in May. 



