238 DURHAM 



Eutamias umbrinus adsitus Allen 



Habitat: The Say chipmunk is the most common one on the North 

 Rim and it occurs widely throughout the timbered areas of pine, fir and 

 aspen. None were taken at the edge of the Rim nor below it. The popu- 

 lation on Powell Plateau is probably isolated, as none were observed at 

 Muav Saddle, the most likely avenue of entrance. 



Color: The specimens show considerable variation in color other than 

 that resulting from age and wear. In the eastern part of the North Rim 

 the underparts of adults and immatures are grayish white, while in the 

 western part the underparts are almost pure white (Howell, 1929, p. 

 93) with hairs, at least on the throat, white to the base. Variations in 

 pigmentation of tail margin are evident, the color ranging from the 

 expected pale buff to cinnamon, as in the least chipmunk. The resemblance 

 to the latter has been pointed out in the account of that species. 



Size: Although Howell {op. cit.) considered the colony on the 

 Kaibab Plateau nearly typical, I found the specimens of the North Rim 

 particularly large in length of head-body, hind foot and nasals (see 

 Table 3). Even the males, which average smaller than the females, are 

 as large as the largest topotypes (Howell, op. cit.). 



Eutamias dorsalis utahensis Merriam 



Habitat: Cliff chipmunks were observed and taken only at Muav 

 Saddle and vicinity, below the canyon rim. Several were observed run- 

 ning over the high, vertical cliffs at the foot of the trail from Swamp 

 Point. Two of the wary animals were trapped in this Upper Sonoran 

 environment. A third was obtained from the shady, wooded slope of 

 Saddle Canyon, which is lower Transition (Bailey, 1931, p. 92). All 

 three were subadult females without embryos. 



Color: The throat is creamy white and the underparts are grayish. 

 The specimens from the North Rim have more conspicuous striping on 

 the head and body and brighter cinnamon on the sides, legs and head 

 than have the E. dorsalis from the South Rim in the Hancock Col- 

 lection. 



Size: These three specimens, although not fully grown, are large and 

 exceed in length of head-body, hind foot and nasals and in breadth of 

 cranium the averages of adult topotypes (Howell, 1929, p. 134). 



