2io FIELD COLUMBIAN MUSEUM ZOOLOGY, VOL. i. 



from specimens of gambelii from Calaveras, Amidor and Eldorado 

 counties, California; nor, strange as it may seem, from P. t. arc- 

 ticus from Wyoming. The young are a pale bluish gray, quite 

 different from those of typical gambelii, but two from Winters 

 Mines are a mealy gray very similar to those of arcticus. It 

 would seem that in this vicinity the three forms approach each 

 other very closely, but there is not so much evidences of inter- 

 grading with the more eastern forms as there is with gambelii on 

 the west, for judging from the series before me, it is impossible 

 to decide where either gambellii or the present subspecies begins 

 or ends, so gradually do they merge into each other. 



35. Peromyscus texanus medius. 



Peromyscus texanus medius. Mearns, Proc. U. S. Nat. Mus., 

 vol. xviii, p. 446, 1895. 



Seven specimens from San Antonio, San Bernardino Co. 



I refer these specimens to Dr. Mearns' subspecies as described 

 above. The measurements of the oldest individuals are some- 

 what less than those of P. t. medius generally, and one, collectors' 

 No. 1040, has the entire upper parts rufous. The measurements 

 of the four oldest examples are : 



Total length. Tail. Hind leg. Ear. 



Collector s No. 1039, $ 162 mm. 74 18 17 



" 1040, $ 150 " 63 18 17 



" I0 35. 9 146 " 62 19.5 16 



" 1004, $ 149 " 62 19 17.5 



FAMILY GEOMYID^:. 



36. Thomomys monticolus. 



Thomomys monticolus. Allen, Bull. Am. Mus. Nat. Hist., 

 vol. v., 1893, p. 48. 



Nineteen specimens, as follows : 9, Silver Lake, Amidor Co.; 

 3, Blue Lake, Alpine Co.; i, Pyramid Peak, Eldorado Co.; 3, 

 Big Trees, Calaveras Co.; 2, Hermit Valley, Calaveras Co.; i, 

 Bloods, Calaveras Co. 



In coloration these specimens resemble on the upper parts the 

 description of the type as given by Dr. Allen (1. c.), but in some 

 there is very little of the gray tint visible, while the under parts 

 vary from ashy white -to a rather deep buff, without any white. 

 Again, in others, the ashy white is almost overcome by the 

 plumbeous of the basal portion of the fur, giving the under sur- 



