434 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 
Castor americanus R1CHARDSON, Back’s Arctic Land Exped., 1836, 494.—BranpT, Mém. Acad. St. Pétersb., 
6th ser., Sci. Nat., vii, 1855, 64, pls. i, ii, iii (tail and skull).—MaxIMILLaNn, Wiegm. Arch., 
1862, i, 132. : 
Castor europeus OWEN, Brit. Foss. Mam., 1846, 190. 
Castor fiber seu europ@us Branpt, Mém, Acad. St. Pétersb., 6th ser., Sci. Nat., vii, 1855, 63. 
Castor fiber var. ewropwus MORGAN, Amer. Beaver and his Works, 1868, 44. 
Le Castor ou le Biévre, Brisson, Régne, Anim., 1756, 133. 
Castor Beaver, PENNANT, “ Synop. Quad., 255 ; Hist. Quad., 1781, No. 251”; Arctic Zodl., 2d ed., i, 1792, 113, 
The Beaver, LAwsoNn, Hist. Carolina, 1871, 121.—Catessy, Nat. Hist. Carolina, 1731, i, xxix.— BRICKELL, 
Nat. Hist. N. Car., 1737, 121.—HeEaRNE, Journ. to the Northern Ocean, 1795, 226.—HECK- 
WELDER, Trans. Amer. Phil. Soc. 1st ser., vi, 1809, 209 (babits).—BuckKLEy, Amer. Journ. 
Sci. and Arts, 2d ser., iii, 1846, 434 (North Carolina).—BRUMLEY, ibid., iv, 1847, 285 (Ala- 
bama).—A. AGassiz, Proc. Bost. Soc. Nat. Hist., xiii, 1869, 100 (Beaver dams).—BrRuUNOT, Ann. 
Rep. Smith. Inst. for 1873, 1874, 422 (habits). 
Le Castor du Canada, F. Cuvier & Greorrroy, Hist. Nat. des Mam., i, liv. 6, 1819 (figure). 
Castor d’ Europe, F. Cuvier & GEeorrroy, ibid., iii, liv. 51, Oct. 1825 (figure). 
DESCRIPTION. 
Body thick, heavy, depressed, enlarging posteriorly, broadest near the 
hips; head large and broad; muffle naked; nostrils lateral, divided; ears 
short, rounded, furred, and nearly hidden in the pelage; tail broad and flat, 
covered with horny blackish scales; fore feet short and weak, unwebbed ; hind 
feet large, fully palmate; soles of all the feet naked, upper surface hairy ; 
second toe of hind feet usually furnished with a double claw, the supple- 
mental one being placed transversely beneath the true one; under-fur soft, 
dense, and grayish; overlying hairs coarse, shining-chestnut. Length of 
body, about 30 inches; of tail, about 10; weight of adult, about 45 to 50 
pounds, ranging to upward of 60. 
The general color of the Beaver above is reddish-brown, varying to 
lighter or darker in different individuals and probably with the season; 
lighter, approaching grayish, below. The Beaver appears to be generally 
darker to the northward, where it is occasionally nearly black. Albinistic 
individuals are also more or less frequent, either wholly white, creamy white, 
or with patches of white. To such specimens have been given the various 
varietal names of nigra, albus, variegatus, flavus, ete. 
The Beaver is apparently several years in attaining its growth, increas- 
ing in size long after it has acquired its mature dentition. Two-year-old 
Beavers generally weigh about thirty-five to forty pounds, while very old ones 
occasionally attain a weight of upward of sixty.. Morgan records the capture 
of one which weighed sixty-three pounds. The increase in the size of the 
skull seems to continue nearly through life; in old age the skull not only 
acquires larger dimensions, but the weight is relatively greater in conse- 
