Castor canadensis leucodonta [Gray], Ann. and Mag. Nat. Hist., 4 (ser. 4):293, October, 1869.
Castor canadensis pacificus [Rhoads], Trans. Amer. Philos. Soc., 19 (n. s.):422, September, 1898 (type from Lake Keechelus, Kittitas County, Washington).
Type.—Obtained by Dr. Robert Brown, probably on Vancouver Island, British Columbia.
Racial characters.—Large size; reddish color; elongate skull.
Distribution.—Found over all but the southwestern corner of the state. The most westward locality from which specimens have been examined is Lake Crescent (U. S. N. M.).
Remarks.—The good series of beaver skulls available from several areas of Washington has led to careful comparison of Washington material with specimens from Vancouver Island. Skulls from extreme southwestern Washington are small and decidedly short, being referable to the race idoneus. No satisfactory way of distinguishing between the others could be found and all are consequently referred to the earliest named form, leucodonta.
Castor canadensis idoneus Jewett and [Hall]
Castor canadensis idoneus Jewett and [Hall], Jour. Mamm., 21:87, February 15, 1940.
Type.—Obtained at Foley Creek, tributary to Nehalem River, Tillamook County, Oregon, by C. Leach on December 15, 1914; type in California Museum of Vertebrate Zoölogy.
Description.—Similar to leucodonta but smaller, darker, with shorter and wider skull.