VARIATIONS OF RODENTS 237 



new pelage and another in faded, worn pelage (Hall, 1946, p. 319). 

 Furthermore, the faded pelage of the one obtained from the juniper- 

 pinyon belt at Jacob Lake near the north edge of the Kaibab Plateau 

 was no paler than the one in worn pelage taken from Robber's Roost 

 in aspen country. North Rim. Regardless of sex, subadults (probably 

 yearlings) apparently start molting first and have their new coat by 

 July 15. Most adult females have only a small area of new hair on the 

 forehead by July 1, although one female suckling young was in new 

 pelage on June 29. 



Eutamics minimus consobrinus (Allen) 



Habitat: Only three least chipmunks were taken on the North Rim 

 and all these were from Tipover Spring where the Transition forest 

 consists of yellow pine, spruce and fir. In the field I could not distinguish 

 between them and the more numerous Say chipmunks (see below) taken 

 in the same trap line. 



Size: Although the three specimens taken are subadults, they equal 

 or exceed in every skull and body measurement except total length and 

 length of tail the maximum measurements given for specimens from 

 Utah (Howell, 1929, p. 47 and Durrant, 1952, p. 133 and 154). The 

 skull measurements are 3 to 8 per cent larger, the length of head-body 

 5.8 per cent larger; but the tail is actually and relatively shorter, aver- 

 aging 76.5 per cent of head-body length against 82.5 per cent for speci- 

 mens from Utah (Howell, op. cit.). The hind feet are large but in the 

 usual proportion (28 per cent or slightly more) to length of head-body. 

 The tails and feet of these subadults may not be fully developed. 



These young specimens of E. m. consobrinus are about the size of 

 large individuals of the subspecies operarius from the opposite side of the 

 Colorado River, between whose ranges there is thought to be no inter- 

 mingling. They are also near the size of the smallest Say chipmunks of 

 the North Rim and were distinguished from the two dwarfed adults of 

 that species from the Walhalla Plateau only by the use of minimum 

 lengths for the Say chipmunks, i.e., head-body 120 mm, skull 33.5 mm 

 (Johnson, 1943, p. 71), and hind foot 33 mm. The maximum correspond- 

 ing measurements of the minimus from the North Rim are: 112, 32.3 

 and 32 mm. These specimens verify the statement of Johnson {op. cit.j 

 p. 79) concerning the great variability of the least chipmunk in the 

 Rocky Mountain region. 



