1()4l Merriam — New Chipmunks from Cnlonuln and Arizona. 



inoiintain species is slightly i^mt^Ht'i" tlian the foot-liills form, 

 hut tlu' name ''' qKadricittatii-s^' lias lu'en ('(immoiily applied to 

 hoth. Say's original description is equally applical)le to hoth, 

 except for the measurements, wliich were given as follows : 

 Length from the nose to thi' hase of the tail, 4.f inches, 

 of the tail, 3 



of the hair at tip of the tail, 1 nearly." 



As we measure mammals nowadays, Sa^^'s measurements of 

 body and tail are too small for even the smaller of the two 

 species, but it must l)e remember(Ml that at the time Hay wrote, 

 and for half a century afterwards, no ruh^s for th(^ measurement 

 of mammals had Ix^m formulated, and that by the old method 

 the dimensions recorded were considerably less than by prestmt 

 methods. Furthermore, the ditfeiHaice in size of the two species 

 is so slight that the fact that there are two species in the 

 region appears to have thus far escaped the attention of 

 naturalists. The third measurement given by Say, that of the 

 length of hair at tip of tail, agrees best with the larger species — 

 the tail liairs of the smaller one, particularly in worn summer 

 pelage, falling (■onsi(lei'al)ly short of an inch. 



Field work con<lucted in t'oloi'ado by se\'eral tield naturalists 

 of th<^ Biological Survey (E. A. Prehle, .J. Alden Loring, and 

 Vernon Bailey) has demonstrated the fact that the larger of thi' 

 two chipnumks is connnon throughout the Arkansas Valley in 

 the region at which the type specimen was ol)tained, and that 

 the small mountain s[)ecies does not occur in the region at all 

 and can not be foimd until the mountains are penetrated far 

 enough to reach the Boreal zone. This shows l)eyond question 

 tliat Say's (jiia(lririt(iihi--< is the foot-hill chipmunk of easteni 

 L'olorado, and that the moimtain species, which has connnonly 

 been included under this name, rcquirt's a new name. 



Comparison of the C'olorailo mountain cliipmunk with the 

 other small chipnund<s of the West shows that its nearest rel- 

 ative is h\ aiiKiiuis oi the California Sierra, thus affording another 

 instance of the close relationship of species iidiabiting the moun- 

 tains bordering the two sides of the (Jn'at Basin. 



Eutamias amoenus operarius siibsi). iiov. 

 Tiipe from Gold Hill (altitude 7,400 feet), Colorado. No. 129,808, 9 young 

 adult, U. S. National Museum, Biological Survey Collection. October 8, 

 1903. Vernon Bailey. Original No. 81H0. 



