434 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 



Castor americamis Richardson, Back's Arctic Land Exped., 1836, 494.— BRANDT, Me"iu. Acad. St. P6tersb., 

 Cth ser., Sci. Nat., vii, 1855, 64, pis. i, ii, iii (tail and skull). — Maximillan, Wiegm. Arch., 

 1862, i, 132. 



Castor curopmus Owen, Brit. Foss. Mam., 1840, 11)0. 



Castor fiber seu europwns BRANDT, Mem. Acad. St. Pe'tersb., Cth ser., Sci. Nat., vii, 1855, C3. 



Castor fiber var. europaniB MORGAN, Amer. Beaver and his Works, 1808, 44. 



Le Castor ou le Biivre, Brisson, Rogue, Auim., 1756, 13:1. 



Castor Beaver, Pennant, " Synop. Quad., 255 ; Hist. Quad., 1781, No. 251 " ; Arctic Zool.,2d ed., i, 1792, 113, 



The Leaver, LawSON, Hist. Carolina, 1871, 121.— Catesby, Nat. Hist, Carolina, 1731, i, xxix.— Brickell, 

 Nat. Hist. N. Car., 1737, 121.— Hearne, Journ. to the Northern Ocean, 1795, 226.— Heck- 

 welder, Trans. Amor. Phil. Soc. 1st ser., vi, 1809, 209 (habits).— Buckley, Amer. Jouru. 

 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, 18U9, 100 (Beaver dams). — Brunot, Ann. 

 Rep. Smith. Inst, for 1873, 1874, 422 (habits). 



Le Castor da Canada, F. Cuvier & Geoffroy, Hist. Nat. des Mam., i, liv. (5, 1819 (figure). 



Castor oVEurope, F. Cuvier & Geoffroy, 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, jiavus, etc. 



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- 



