24 Gary Some Unrecorded Colorado Mammals. 



Sonoran form, and probably ranges continuously across northeastern Utah 

 along the southern foothills of the Uinta Mountains, entering Colorado in 

 the region of the Yampa Plateau, south of Bear River. I was surprised to 

 find it absent from the pinon-covered ridges on either side of the lower 

 White River Valley. 



Eutamias minimus (Bachman). 



Chipmunks from the sage plains of the lower Snake River Valley and 

 Browns Park, in western Routt County, agree perfectly with typical speci 

 mens of E. minimus from Green River, Wyoming. Three males and one 

 female were collected in 1906, at the following localities: Snake River (15 

 miles northeast of Sunny Peak), August 24; Snake River (south of Sunny 

 Peak), August 28 ; Ladore (Browns Park), September 3. Towards the 

 mountains on the south and east, minimus grades into the dark form con 

 sobrinus, specimens from Lay, Axial Basin, and Lily being intermediate in 

 coloration. 



Eutamias minimus consobrinus (Allen). 



This is the small, dark chipmunk so abundant on all the higher plateaus 

 and mountains west of the Front Range, and north of Grand River. It is 

 chiefly an inhabitant of the Canadian and Transition zones, and in the 

 eastern part of its range is the only chipmunk present over a large area. 

 On some of the western plateaus, however, E. consobrinus ranges down a 

 short distance into the cedar and pinon belt of the Upper Sonoran zone, 

 and there commingles with the large Hopi chipmunk (E. hopiensis). 



E. consobrinus is represented by a large series in breeding and fresh 

 post-breeding pelages, and a few in the early winter coat. Specimens were 

 secured at the following localities : Middle Park (Coulter, Sulphur Springs, 

 Mount Whiteley) ; North Park (Arapahoe Pass, Canadian Creek, Pearl) ; 

 Slater (20 miles southeast) ; White River Plateau (25 miles southeast of 

 Meeker) ; Meeker; Rangely ; Gypsum ; and Baxter Pass (Book Plateau). 



Four chipmunks in the National Museum, collected by Capt. Bowman 

 at old Fort Massachusetts (near the present site of Garland), have been 

 recorded as E. consobrinus* These are faded flat skins which were made 

 up with the skulls inside. The skulls have been removed and cleaned 

 through the courtesy of Dr. M. W. Lyon, Jr. , and are found to be larger and 

 more robust than skulls of typical consobrinus. A comparison with the 

 skull of the type of Eutamias amoenus operarius from Gold Hill, Boulder 

 County, proves that the Fort Massachusetts chipmunks are properly refer 

 able to that species. 



Eutamias amoenus operarius Merriam. 



Eutamias amoenus operarius Merriam, Proc. Biol. Soc. Wash., XVIII, p. 



164, June 29, 1905. Type from Gold Hill, Boulder County, Colorado. 

 This chipmunk is most abundant in the boreal zones on the eastern 

 slope of the Front Range, but is found as low as 6,500 feet at several lo 

 calities in the eastern foothills. It ranges far above timber line, and across 

 * Allen, Bull. Am. Mus. Nat. Hist., Ill, p. 113, 1891. 



