1869.] 193 [Allen. 



As I have previously observed, 1 1 believe that a considerable number 

 of merely nominal species of Hesperomys have been recognized as 

 valid, and in a group presenting such a wide range of variation in 

 color and in the proportions of the different parts of the body as 

 different representatives of even the restricted H. leucopus do, I fail 

 to see the propriety of basing species on such intangible differences 

 as distinguish H. sonoriensis. 



42. Hesperomys miehiganensis Wagner. (Prairie White- 

 footed Mouse.) 



Apparently common; several specimens taken. I made my first 

 acquaintance with this species in life, in Ogle county, Illinois, where 

 I found a pair in June in their nest under a flat stone at the edge of a 

 cornfield. A newly born Utter of young were attached to the teats 

 of the female. The contrast of color between the dorsal and ventral 

 areas of the body was well marked, and the line of separation along 

 the sides clearly defined. 2 



The Wood Rat (Neotoma floridand) has been found in northwest- 

 ern Kansas, about a hundred miles from the southwestern corner of 

 Iowa, and judging from what is known of its distribution, it may be 

 expected to occur in portions of the latter State. 



43. Arvicola riparius Ord. (Meadow Mouse.) 

 Apparently common. I obtained several specimens, some of which 



are scarcely appreciably different from Massachusetts ones; others more 

 resemble some obtained by me in Northern Illinois. In the latter 

 locality I obtained young specimens in the fall that in general char- 

 acters are referable to A. riparius, but which in the character of the 

 fur are quite different from the ordinary type of this species at the same 

 age at the East, the coat being longer and heavier; the longer hairs 

 presented a more bristly appearance, many of which were hoary, thus 

 giving a well-marked grizzly aspect to the pelage. In the long heavy 

 coat it seems to correspond with the prairie variety mentioned by 

 Prof. Baird, and to which he applied the name longipils, in reference 

 to this peculiarity; but they differ from it in color, which may, how- 

 ever, and most probably does, result from a difference in age. The 

 longer and coarser pelage noticeable in the Arvicola of the prairie is 

 similar to that previously referred to in this paper as characterizing 

 the prairie minks. 



1 Bull. Mus. Comp. Zool., No. vm, p. 227. 



2 Compare with this the remarks of Mr. Kennieott and Prof. Baird in reference 

 to " Mus Bairdii." Pat. Office Pep., Agr., 1856, p. 92 ; Mam. N. Amer., p. 477. 



PROCEEDINGS B. S. >\ H.— VOL. XIII. 13 FEBRUARY, 1870. 



