MAMMALS OF MINNESOTA. 163 



the outer, are whiter, varying from grayish- white to pure white; 

 the sides of body, especially anteriorly, are brignt reddish fer- 

 ruginous; the tail yellowish-rusty, with a sub terminal border 

 of black edged with yellowish." The habitat assigned to this 

 variety is the middle and southern portions of the Rocky moun- 

 tains from near the northern boundary of the United States to 

 New Mexico, westward to Pacific coast, eastward to the plains. 



It is quite difficult to decide to which of the nominal varieties 

 these specimens belong. They occur in the range of borealis, 

 have the colors of quadrivitattus and size of pallidus. As a 

 matter of fact, very likely these varieties do not express all of 

 the tendencies to variation which seem to be governed by the 

 actually existing conditions of life rather than to express the 

 genetic relations. 



The osteology of the Asiatic chipmunk would be of value 

 only as taken together with a description of the entire anatomy 

 and a minute comparison with other species of the genus, with 

 a view to discover what relations exist between these closely 

 allied species. A few measurements may prove instructive, as 

 affording a means of comparison with T. striatus. 



Skull length, 1.25 (T; striatus, 1.60), width, 0.82 (0.97), nasals, 

 0.38 (0.51), incisors, to palate, 0.65 (0.85), between molars, 0.20 

 (0.24), rames, 0.80 (1,10). 



Shoulderblade, 0.60 (0.80), humerus, 0.70 (0.90), ulna, 0.88 

 (1.00), longest metacarpal, 0.20 (0.28), pelvis, 0.85 (1.08), femur, 

 0.95(1.10), tibia, 1.10 (1.21), longest metatarsal, 0.50 (0.54). 



These figures indicate a much more slender skull in T. stria- 

 tus (1.46 1.64 being the width to length ratios approximately). 

 This is largely due to the greater facial prolongation of the 

 latter, in which the nasal bone is contained 3.13 times in the 

 length of the skull, while in the smaller species it is 3.28 times. 



The humerus is shortest proportionally in T. asiaticus (1.35 

 and 1.22 being the proportions between humerus and femur in 

 the two species. ) Perhaps the shorter humerus may be corre- 

 lated with less active and especially less arboreal habits. The 

 T. asiaticus does not seem to burrow as extensively as our chip- 

 munk. The greater length of the tail is as obvious in the 

 skeleton as in the flesh. 



GENUS SPERMOPHILUS, F. Cuv. 



This genus, a synopsis of which is given beyond, contains 

 about twenty species confined to the northern continents of 



