MAMMALS OF THE MEXICAN BOUNDARY. 285 



Of nock, and cheeks (below malar stripe) gray, tbis color extending back to pos- 

 terior border of scapular region, but there more blackish, and sometimes with a 

 faint tinge of brownish suffusion. Thighs and buttocks very faintly tinged 

 with pale yellowish brown. Dar|i dorsal stripes broad, deep black, edged with deep 

 chestnut brown, the outer one on each side narrower, shorter, and less blade, 

 but sharijly defined and strongly marked. Inner pair of light dorsal stripes 

 clear whitish gray ; outer pair broader and clear white. Light facial stripes 

 rather clear white ; the dark Ones very broad, dull rusty brown, the ocular 

 stripe alone much mixed with black, generally distinctly black immediately 

 before and behind the eye. Ears externally with the central area blackish, 

 the anterior border rusty, and the posterior broadly edged with grayish white ; 

 inner surface pale rusty. Light patch behind the ear light gray, scarcely lighter 

 than the surrounding pelage, and hence not conspicuous. Tail above blackish, 

 the hairs ochraceous at base and tipped broadly with buff ; below broad central 

 area orange rufous, bounded by a very narrow line of black, fringed with buff. 



Breeding pelage (May-July). — Pelage softer and fuller (comparing especially 

 May and August specimens) ; colors all dull and bleached, the tints of gray, 

 black, and white, all less pure and clear, and the sides only faintly washed with 

 pale yellowish brown, varying in different specimens to pale buff, sometimes 

 not appreciably different from the pale dull yellowish gray of the general color 

 of the dorsal surface. 



Yonng. — Half-grown young are similar in color to adults in August and Sep- 

 tember, but the ijelage is thinner and more silky, with the unmistakable look 

 of juvenility. (Bull. Am. Mus. Nat. Hist, III, p. 94.) 



Measurements. — Average of three adult males: Length, 223 mm.; 

 tail to end of vertebrae, 95 ; tail to end of hairs, 118 ; hind foot, 34.3 ; 

 ear from crown, 15.1 ; ear from notch, 20.3 ; head, 38.3 ; from tip of 

 nose to eye, 16.3; nose to ear, 30. Average of ten adult females: 

 Length, 225 mm. ; tail to end of vertebrte, 99 ; tail to end of hairs, 

 125 ; hind foot, 34.1 ; ear above crown, 16 ; ear abbve notch, 20.1 ; 

 head, 39.5 ; nose to eye, 15.8 ; nose to ear, 30.6. Skull, 37.3 by 20.7. 

 Mammae, four pairs. 



Cranial and dental characters. — The skull closely resembles that of 

 Eutamias dorsalis, but is shorter, the brain case being shorter and 

 relatively broader, with rostrum slightly shorter and more depressed. 

 The nasals are broad like those of dorsalis; incisors narrower. 



Life history. — The Arizona chipmunk is of strictly alpine distri- 

 bution. Its habitat is restricted to the evergreen forests, from an alti- 

 tude of about 6,500 feet nearly up to timber line (11,468 feet). Its 

 lowest range barely touches the upper limit of that of the Gila chip- 

 munk {Eutamias dorsalis). It does not descend to the lower limit of 

 the pine belt, and is most abundant in the fir and spruce forests, at an 

 elevation of from 7,000 to 11,000 feet. The Gila chipmunk, on the 

 other hand, finds its upper limit in the pine belt, which it penetrates 

 to the altitude of 6,500 feet. 



As might be predicted, the Arizona chipmunk descends to the 

 lowest level along the borders of the largest areas of its habitat, as in 

 the San Francisco Forest and Mogollon Mountains. There are many 

 smaller areas which, from their altitude and vegetation, would afford 



