40 CASTOR. 



mastoid breadth, 67; length of upper molar series, 32; length of man- 

 dible, IIO.Q; length of lower molar series, 39.4. Ex type in United 

 States National Museum. 



Castor canadensis leucodontus Gray. 



Castor ciinadt'nsis Icucoilontus Gray, Ann. and Mag. Nat. Hist., 

 Ser. 4, IV, 1869, p. 293; Osgood, Proc. Biol. Soc. Wash., XX. 

 1907, p. 47. 



Castor caiiaijf/isis pacificus Rhoads, Proc. Am. Philos. Soc., N. S., 

 XIX, 1898, pp. 422-423, pi. xxi, fig. i, pi. xxii, fig. i; Elliot, 

 Syn. N. Am. Mamm., F. C. M. Pub., II, 1901, p. 117, Zool. 

 Ser.; Id. Check-List Mamm. N. Am. Cont. and West Indies, 

 F. C. M. Pub., VI, 1905, p. 129. 



Type locality. Lake Kichelos, Cascade Mountains, Kittiloss 

 County, Washington. 



Geogr. Distr. Pacific Slope; California to Alaska. 



This well-known species has usually been recognized as C. c. 



pacificus, the name bestowed upon it by Rhoads (/. c.), but Osgood 



has shown (I. c.) that the name C. c. leucodontus was given it by Gray 



(/. c.) as far back as 1869, and that is the one it must bear in the future. 



Castor canadensis michiganensis Bailey. 



Castor canadensis michiganensis Bailey, Proc. Biol. Soc. Wash., 

 XXVI, 1913, p. 192. 



Type locality. Tahquamenaw River, five miles above falls, Luce 

 County, Michigan. 



Genl. Char. Color dark; ears, hands and feet black. Skull short, 

 wide, zygomatic arches wide; rostrum short; nasals constricted pos- 

 teriorly; occipital crest present. 



Color. Head and cheeks mahogany-brown; upperparts dark 

 umber-brown; underparts blackish on breast, rest like upperparts 

 but darker; flanks blackish; ears, hands and feet black. Ex type iii 

 United States National Museum. 



Measurements. Total length, 1170; tail, 470; hind foot, 183. 

 Skull: Occipito-nasal length, 26.2; intertemporal width, 25.5; Hen- 

 sel, 115.2; zygomatic width, 96.4; length of nasals, 46; palatal length, 

 28.3; length of upper molar series, 29.4; mastoid breadth, 65; length 

 of mandible, 92.7; length of lower molar series, 31.4. Ex type in 

 United States National Museum. 



Castor canadensis mexicanus Bailey. 



Castor cau<!<l<')isis nn-.virtinus Bailey, Proc. Biol. Soc. Wash., XXVI, 

 1913, p. 191. 



