1913] Grinnell-Swarth: Birds and Mammals of San Jacinto 355 



result of this isolation. The nearest relative of altivallis appears 

 to be Thomomys alpinus of the Mount Whitney region, also a 

 boreal species. The chief appreciable differences between the 

 two lie in the somewhat smaller size of alpinus, and in its slightly 

 grayer general coloration and constantly white throat. The lat- 

 ter peculiarity is possessed by some examples of altivallis from 

 the San Jacinto mountains, as above noted. 



All of our San Jacinto specimens were trapped on or around 

 meadows, but gopher workings were also plentiful on well- 

 drained ridges in the vicinity, as all through the lodge-pole pine 

 belt surrounding Round Valley. 



List of Measurements in millimeters op full-grown females of 

 Thomomys altivallis 



Mus. 



Locality 

 Tahquitz Valley, San Jacinto Mts. 

 Tahquitz Valley, San Jacinto Mts. 

 Tahquitz Valley, San Jacinto Mts. 

 Round Valley, San Jacinto Mts. 

 Round Valley, San Jacinto Mts. 

 Average of the five $$ 

 Average of 44 $5? of T. altivallis from 



the San Bernardino Mts. 223 68 30.5 



Dipodomys merriami simiolus Rhoads 

 Allied Kangaroo Rat 



Forty-six specimens of this four-toed kangaroo rat were 

 obtained in the San Jacinto region, representing the following 

 stations: Dos Palmos Spring, 3500 feet, ten (nos. 1920-1927, 

 1938, 1939) ; Palm Springs, 450 feet, seven (nos. 5348, 5355- 

 5359, 6928) ; Whitewater, 1130 feet, twelve (nos. 1600-1605, 

 1612-1617) ; Snow Creek, 1500 feet, ten (nos. 1606-1611, 1628- 

 1631) ; Cabezon, 1700 feet, seven (nos. 1315-1321). 



These localities will be seen to align themselves strictly within 

 the Lower Sonoran zone on the desert slope of the mountains. 

 At the highest station altitudinally — Dos Palmos Spring — this 

 rodent was associated with Perodipus agilis, in our experience an 

 unusual state of affairs, though this is clearly due to the local 

 overlapping of ranges because of the juxtaposition of the desert 

 and coast faunas. Young had appeared in numbers, during the 



