154 
and in modifications of structure, adapting them to an arboreal, rather 
than to a terrestrial life. 
The molars are 423; body more or less armed with spines. Three of 
the New World genera are South American; the fourth, “rethizon, 1s 
found north of Mexico. ; 
GENus Ereruizon F. Cuvier. 
Ktymology: Hrethizo—to irritate. 
Hystrix, in part of early authors. 
Hrethizon, F. Cuvier, Mém. du Mus, ix, 1822. 
Echinoprocta, Gray, Proc. Zool. Soc. Lond., 1865, 321. 
Toes four in front and five behind, all armed with strong, curved 
claws. Tail short, thick, depressed, non-prehensile; covered above, at the 
base, with stiff hairs and spines, and on sides, at apex; and beneath, 
with thick, rigid bristles. Size large. Limbs short and strong. 
The genus Hrethizon is represented by a single species, divisible into 
two geographical yvarieties—the Canada Porcupine, JL. dorsatus var. dor- 
satus, and the Western Porcupine, var. epixanthus. 
HWRETHIZON poRSATUS (Linn.) F. Cuvier. 
Var. dorsatus. 
CaNADA PORCUPINE. 
1758. Hystrix dorsata, Linn., Syst. Nat., ed. x, 1, 1758, 57, ed. xii, i, 1766, 
76.—Forster, Phil. Trans., lxii, 1772, 374.—Erxleben, Syst. Reg. 
Anim., 1777, 8345.—Gmelin, Syst. Nat., 1, 1784, 119.—Schreber, 
Saugt., iv, 1792, 605, pl. clxix.— Shaw, Gen. Zool., ii, 1801, 13, 
pl. cxxv-—Kukhl, Beitrige zur Zodlogie, 1820, 70—Desmarest, 
Mam , 1822, 345.—J. Sabine, Franklin’s Journey to the Polar 
Sea, 1823, 664.—Cozzens, Ann. N. Y: Lyc. Nat. Hist., i, 18238, 191. 
—Harlan, Fauna Amer, 1825, 180.—Godman, Amer. Nat. Hist., . 
ii, 1826, 50.—Griffith’s Cuvier, iii, 1827, 206; v, 1827, 263.— 
Fischer, Synop. Mam., 1829, 868—Hmmons, Quad. Mass., 1840, 
71.—Thompson, Hist. Vermont, 1842, 47.—Aud. & Bach., 1, 1843, 
BO, lly SRW 
1731. Hystrix pilosus americanus, Catesby, Nat. Hist. Carolina, 1, 1731, xxx. 
1756. Hystrix hudsonis, Brisson, Régn. Anim., Quad., 1756, 128. 
1842. Hystria hudsonius, DeKay, New York Zodl., i, 1842, 27, pl. xxv, fig. 
1 (animal), pl. viii, figs. 2, a, b, ¢ (skull). 
1835. Hrethizon dorsatus, F. Cuvier, Mém. du Mus., ix, 423, pl. xx, figs. 1, 
2,8 (skull and molar).—Brandt, Mém. Acad. St. Petersbourg, 
1835, 887.—Waterhouse, Nat. Hist. Mam., 11, 1858, 438.—Giebel, 
Siuget., 1855, 478.— Wagner, Suppl. Schreber’s Sauget., iv, 1844, 
