MAMMALS OF MINNESOTA. 209 



The single species thus far found under the genus Onychomys 

 has differentiated into three more or less distinct geographi- 

 cal races or varieties. Of these but one is found in Minnesota 

 and that only upon the western boundary and a very short dis- 

 tance east of it. 



The typical form is stated to be restricted to the upper Mis- 

 souri river region, and is described as follows : 



"Color above, grayish-brown, passing into yellowish-red, 

 and finally into a stripe of fulvous on the sides. Feet, inclu 

 ding outer surface of the forearm and under surface of the body 

 and tail, white." Baird. 



'Beneath, snow-white; above, mouse-brown, with darker 

 dorsal area. Tail twice the hind foot or less ; much less than 

 half the head and body. Fore foot more than half the hind 

 foot. Ear about 0.50 high." Coues. 



' ' The chief distinguishing feature in coloration, as compared 

 with Hespzromys leucopus, is the mostly white muzzle. "Coues. 



The following measurements from No. 7492 of the national 

 museum, are selected as fairly illustrating the proportions : 

 Nose to tail, 4.25; tail, 1.65; hind foot, 0.88; fore foot, 0.50; 

 nose to eye, 0.60; nose to ear, 1.00; ear, 0.50. The skull of a 

 somewhat smaller specimen measured 1.07 (Coues). 



Onychomys leucogaster var. torridus COUES. 



Was founded upon a single alcoholic specimen from Arizona, 

 which differs from the typical form of the species in having 

 rather larger ears and tail and smaller fore feet. The colors 

 are warmer. The following is Dr. Coues' diagnosis : 



"Beneath, tawny- white [?]; above brownish fulvous, with no 

 darker dorsal area. Tail about two and a half times the hind 

 foot ; almost half as long as head and body. Fore foot half the 

 hind foot. Ears about 0.75 high." Coues. 



Without discussing the characters on which this variety is 

 founded, we may remark that in the only form which we have 

 seen, the proportional length of the tail and limbs were found 

 to be subject to considerable variation, and that even while the 

 exact pattern of coloration was maintained. Coues gives the 

 following measurements of the specimen described : ' ' Nose to 

 tail, 3.75 ; tail, 2.00 ; hind foot, 0.80 . fore foot, 0.40 ; nose to eye, 

 0.50 ; nose to ear, 0.95 ; ear, 0.70. 



