350 BULLETIN 56, UNITED STATES NATIONAL MUSEUM. 



Genus CASTOR Linnaeus (1766). 



Castor Linmjn Syst. Nat, l'-'th ed., 1766, I. p. 78. 



The upper molar teeth are subequal, each with one internal and 

 two external enamel-folds; the stomach has a large glandular mass 

 situated to the right of the oesophageal orifice; the anal and urethro- 

 genital orifices open within a common cloaca: the tad is broad, hori- 

 zontally flattened, and naked; and the hind feet are webbed. {Flower 

 and Lydekker. ) 



CASTOR CANADENSIS FRONDATOR Mearnr. 

 BROAD-TAILED BEAVER; SONORAN BEAVER. 



Castor canadensis frondator M-earns, Proc. V. S. Xat. Mus., XX, p. 503, Jan. 19, 

 1898, (advance sheet issued Mar. •">, 1897; original description. — Miller and 

 Rehn, Proc Bust. Soc. Xat. Hist., XXX, X... 1, Dec. 27, 1901, p. 6:5 (Syst 

 Results Study X. Am. Maui, to close of 1900). 



[Castor canadensis] frondator, Elliot, Field Col. Mus.,Zool. Ser., 11, 1901, j>. 1 Hi 

 i Synop. Maui. X. Am.). 



Castor c[anadensis] frondator, Elliot, Field Col. Mus., Zool. Ser., IV, 1!)()4, pp. 

 159 to 161, fig. 30 (skull of type); fig. 34 (animal). (Mam. Mid. Am.). 



I'ltli-Iitnn'-t'ih of the Hopi Indians. 



Ap-e'-na of the Hualapai Indians. 



Type-locality. San Pedro River, Sonora, Mexico, near Monument 

 Xo. 98. (Type, skin and skull, Xo. |§lff, LI. S. National Museum.) 



Geographical range. — This form occupies the southern interior area 

 of North America, ranging north from Mexico to Wyoming and Mon- 

 tana, its habitat being, of course, restricted to the vicinity of wooded 

 streams, which it follows through the Austral and Transition zones. 



Description. — Larger than the beaver of Canada, paler and different 

 in coloration, with a much broader tail. Above russet, changing to 

 chocolate on the caudal peduncle above, and to burnt sienna on the 

 feet : foes reddish chocolate. Below grayish cinnamon, brightening 

 to ferruginous on the under side of the caudal peduncle. Sides wood- 

 brown, enlivened by the tawny olive color of the overhair. Length, 

 1,070 mm.; length of tail, measured from anus, 360; length of bare 

 portion of tail, 125; height of ear from crown, 31; height of ear from 

 anterior base, 3."); distance from tip of nose to eye, 68; from tip of 

 nose to ear, 125; nose to occiput, 165; length of manus, with claw, 

 82; length of pes, u it li claw, 185. Skull, 13:5 mm. by 99. Weight, 62 

 pounds avoirdupois. 



Cranial characters. The skull of the European beaver (Castor 

 fiber), which is readily distinguishable from that of the Canadian 

 beaver (Castor canadensis) by its slender build, lengthened nasal 

 hones, and elongated rostral portion, presents still greater differences 



