4GH 



PROCEEDINGS ()K TIIK ACADEMY OF 



[1893. 



m 



base of ear, white. Sides of cheek, neck, 

 belly, thighs and tail washed with pale 

 buff, this color often broadly encroaching 

 upon the pure white -of throat and belly. 

 Upper third of tail colored same as back, 

 darkening to black at the tip. 



Measurements. — Total length, 17!' ; tail, 

 i)2 ; hind foot, 24; ear, from crown, 4 ••">. 

 Skull. — Total length, 26; basilar length 

 17 '5 greatest mastoid breadth, 14; 

 length of nasals, 10*7; interorbital con- 

 striction, 6 - 2; length of mandible, 12; 

 height of coronoid process from angle, 5*2. 

 Ratio of mastoid breadth to basilar length, 

 82 ; of mastoid breadth to total length, 

 53'9 ; of length to breadth of interparietal, 

 71. Lower premolar larger than the 

 last molar; audita] bullae not united by 

 a symphysis but separated by ■, mm. anteriorly ; bullae not project- 

 ing beyond plane of occiput. 



Remarks. — Eight specimens of this species were trapped on the 

 semi-arid foothills at the head of Lake ( >kanagan. They abundantly 

 frequented the open hillsides of bunch grass and sage-bush up to 

 timber line and down to near the lake levels, driving their myriad 

 tunnels without difficulty through the dry, indurated and stony soil. 

 Their habits seem to more closely resemble those of Thomomys 

 than any other genus of burrowing rodent. < hving to their habit of 

 pushing a load of dirt ahead of them it was difficult to catch them in 

 their retreats but a trap set by the mouth of certain foraging exits 

 was more successful. In the daytime they keep underground, coming 

 forth nightly to replenish their larder with the seeds of weeds and 

 grasses. This species was not found in similar localities farther 

 north. It is probably limited to the southern parts of the Great 

 Basin fauna of British Columbia as defined by me in the Proceedings 

 of the Academy of Natural Sciences of Philadelphia, 1893, page 

 25, and extends south into Northeastern Washington. It is very 

 doubtful if its habitat reaches farther west than the more arid 

 foothills of the Cascade Mountains; the Selkirk Range would form a 

 natural barrier to its dispersion eastward. 



