388 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 



palate in Hystrix is broad and flat, and of uniform breadth ; in Erethizon it 

 is narrowed anteriorly, and rises abruptly in Iron) of the molars, and between 

 the molar series presents a prominent, central, ragged keel. "Without 

 going into a further comparison, it may suffice Instate that the structure of 

 the skull in the two forms differs markedly in nearly every detail. 



To the old Linnean genus Hystrix were for many years referred all the 

 known Porcupines from both the Old and the New World. The group was 

 first dismembered by M. F. Cuvier in lc.'22, who divided the Old World 

 species into two groups, Hystrix and Acunlhiuti* and the New World species 

 into three, Erethizon, Synetheres, and Sphingunis (" Sphiggurus''). Brandt, in 

 1835, called special attention to the cranial differences characterizing the 

 Old World and New World species, and adopted Cuvier's genus Erethizon 

 for the North American species, but united the two South American genera of 

 Cuvier into the single genus Cercolabes, which groups have since been com- 

 monly retained, with the limitations and names given by Brandt. Cercolabes, 

 however, seems divisible into two generic groups, for which Cuvier's prior 

 names should be retained.f Chcetomys was established by Gray in 1843 for 

 the Hystrix subspinosa of earlier authors. 



The genus Erethizon is confined to the middle and northerly portions of 

 the North American continent, and is represented by a single species, divisi- 

 ble into two easily distinguished geographical varieties or subspecies. 



ERETHIZON DORSATUS (Linn.) F. Cuvier. 

 Var. dorsatus. 



Canada Porcupine. 



Hystrix dorsata Linn., Syst. Nat., ed. x, i, 1758, 57 ; ed. xii, i, 1766, 76.— Forster, Phil. Trans., lxii, 

 1772, 374.— Erxleben, Syst. Reg. Aninr., 1777, 345— Gmei.in, Syst. Nat., i, 1784, 119.— 

 Schrebeh, Sauget., iv, 1792, 605, pi. clxix.— Shaw, Gen. Zoiil. Mam., ii, 1801, 13, pi. cxxv.— 

 Kuhi., Beitriige zur Zoologie, 1820, 70.— Desmarest, Mam., 1822, 345.— J. Sabine, Franklin's 

 Journey to the Polar Sea, 1823, 664.— Cozzens, Ann. N. Y. Lye. Nat. Eist., i, 1823, 191.— 

 Harlan, Fauna Amer., 1825,190— Godman, Anier. Nat. Hist., ii, 1826, 50. — Griffith's Cuvier 

 iii, 1827,206; v, 1827, 263.— Fischer, Synop. Mam., 1829, 368.— Emmons, Quad. Mass., 1840, 

 71.— THOMPSON, Hist. Vermont, 1842, 47.— Audubon and Bachman, i, 1843, 277, pi. xxvi. 



Erethizon dorsatus F. Cuvier, Mem. du Mus., ix, 423, pi. xx, figs. 1, 2,8 (skull and molar).— Brandt, Mem. 

 Acad. St. P6tersbourg, 1835, 387.— Waterhouse, Nat. Hist. Mam., ii, 1848, 438.— Giebel, 

 Sauget. 1855, 478.— Wagner, Suppl. Schreber's Siiugot., iv, 1844, 27 (in part).— Baird, Mam. N. 

 Amer., 1858 568.— Allen, Bull. Mus! Comp. Zool., i, 1869, 235. 



* Acanthion, although applied to species with the frontal region of the skull only moderately swollen, 

 has not been considered by most later writers as generically separable from Hystrix, the second of the 

 two genera of Hystricinee commonly recognized being Atkerura, first characterized seven years later by 

 M. G. Cuvier. 



t Alston (Proc. Zool. Soc. Lond., 1876, 94) considers Synetheres and Sphingurus as being not generic- 

 ally separable ; he adopts Sphingurus as the tenable name of the group, and hence changes the name 

 of the subfamily from Cercolabinw to Sphingurince, although Synetheres has the precedence in Cuvier's 

 memoir. Gervais, as early as 1852, used the name Synetherina as a subfamily name for the New World 

 Porcupines, which name hence has many years' priority over Spliingurinm. 



