446 University of California Publications in Zoology [Vol. 12 



certain cranial dimensions, condition of median process of inter- 

 pterygoid fossa, and outline of nasals. 



CASTOR SUBAURATUS SUBAURATUS TAYLOR, FROM THE 

 SAN JOAQUIN VALLEY, CALIFORNIA 



Material 



Eleven specimens, skins with skulls, in collection of Museum of 

 Vertebrate Zoology: Westley, near Grayson, Stanislaus County, 

 California, 1 (no. 8869) ; Grayson, Stanislaus County, 2 (nos. 8987, 

 8988) ; Tuolumne River, 5 miles north of Grayson. 2 (nos. 12668, 

 12669) ; San Joaquin River, 5 miles north of Grayson, 1 (no. 

 12654) ; San Joaquin River, 10 miles north of Grayson, 4 (nos. 

 16382-16385); "Sespe River, Ventura County, California", locality 

 possibly erroneous, 1 (no. 4918, skull only). 



Comparison With Castor canadensis pacificus Rhoads, from Washington 

 State, and Castor canadensis frondator Mearns, from the Colorado and 

 San Pedro Rivers, Mexico. 



General external characters 



Specimens compared. — Castor subauratus subauratus, nos. 8869, 

 8987, 8988, 12654, 12668, 12669, 16382-16385, Mus. Vert, Zool., all 

 from the general vicinity of Grayson, San Joaquin River, Stanis- 

 laus County, California, taken November 22 to March 25; Castor 

 canadensis pacificus, no. 126190, U. S. Nat. Mus., Keechelus Lake, 

 Washington, February (?), 1903; Castor canadensis frondator, no. 

 20751, U. S. Nat. Mus., San Pedro River, Sonora, Mexico, October 

 14, 1892. 



Comparative material illustrative of external characters is inade- 

 quate, as the list of specimens compared shows. While of subaura- 

 tus there is a good series, one skin only of pacificus is available, 

 and tins is representative of a young individual. The single speci- 

 men of frondator is an adult. Fortunately all the skins were taken 

 during the winter months, so seasonal discrepancy is eliminated. 



The California skins have less hair above than has the example 

 of pacificus. Several of them have thinner hair below, also. 



Coloration in subauratus is remarkably close to that in pacificus 

 as illustrated in the material here compared. The color of the Lake 

 Keechelus example has a slightly paler cast than that of the average 

 of subauratus, for the reason that the overhair of the example of 



