256 FIELD COLUMBIAN MUSEUM ZOOLOGY, VOL. i. 



10. Evotomys nivarius. 



Evotomys nivarius. Bailey, Proc. Biol. Soc., Wash., 1897, p. 

 136. 



This is apparently an Alpine species and was obtained in the 

 same localities in which Phenacomys olympicus was procured. 

 Although I have not seen any example of E. nivarius, the descrip- 

 tion of that species given by Mr. Bailey (1. c.) appears to agree 

 so well with the general aspect of my specimens, that I have 

 little hesitation in considering them to be the same.* The meas- 

 urements of my examples, however, are somewhat less than those 

 given for E. nivarius, and the largest out of twenty- two indi- 

 viduals has the following dimensions: Total length, 137 mm.; 

 tail, 40; hind leg, 16; ear, 8. In the places where this mouse 

 was taken, the ground everywhere was studded with small holes, 

 apparently the entrances to underground galleries, but, with only 

 here and there an exception, these were only a few inches in 

 depth. Now, whether this species has a very changeable mind 

 and abandons one spot after another after digging a few inches, 

 or makes these shallow excavations in search of the roots of cer- 

 tain grasses, or merely for the purpose of supplying a favorable 

 spot on a side hill to sun itself and look around, of course I could 

 not very well ascertain, but certain it was only a very few of the 

 innumerable cavities had any depth, or extended beneath the sur- 

 face. This species seems to dwell in colonies by itself, for in 

 such places as just described, it was only rarely that any other 

 kind of mouse was taken. The adults among my series have the 

 dorsal surface strongly marked -with chestnut, in striking con- 

 trast to the grey and buff of the sides of the body. The tail is 

 more strikingly bicolor in immature specimens than in the adults, 

 some of which exhibit but little difference in the coloring of the 

 upper and lower surface of this member. 



Twenty-two examples: 18, Happy Lake; 4, Boulder Lake. 



shoulders and thighs, pale greyish-buff, nearly clear buff along the belly. Entire under parts and 

 under sides of fore and hind limbs white, the blue of the base of the hairs showing along the sides; 

 chest and abdomen tinged with yellow. Hands and feet white to the wrists and ankles. Tail bushy, 

 same color as the back for about an inch and a half at the root, remainder blackish-grey; under 

 side white. Ears with hairy fringe along outer edge, blackish; rest of ear naked. Whiskers very- 

 long, black with white tips. Measurements taken from the skin: Total length. 408 mm.; tail to 

 end of hair, 194 ; hind leg, 37. The specimen, the only one I have, is without the skull. 



Since this was written Dr. Merriam kindly forwarded to me by Mr. Bailey a topotype of 

 E. nivarius, which proved my specimens to belong to that species. 



