SCIURID^— ARCTOMYS MONAX. Oil 



Spermophilus, differing scarcely mure from Sciurus than do (lie Otospermo- 

 philine forms of Spermophilus. On the other hand, it is in these features 

 that Cynomys is highly specialized. The skull of Arctomys, viewed in its 

 totality, differs from the Sciurine forms of Spermophilus mainly in its very 

 much larger size, and in its much straighter dorsal outline. This, in part, 

 results from the depression of the interorbital region, and in part from the 

 great development of the occipital crests, naturally correlating with the large 

 size and heavier form of the animal. The triturating surface of the molar 

 teeth in Arctomys presents two deep transverse grooves, extending from the 

 outer edge to the middle of the tooth, instead of three, as in Cynomys, 

 agreeing in this respect with Spermophilus, Tamias, and Sciurus. The first 

 upper premolar is relatively not larger than it usually is in Spermophilus, and 

 is smaller, absolutely as well as relatively, than in Cynomys. 



The genus Arctomys embraces the largest members of the Sciurulcr, 

 and, excepting Castor, the largest of the existing North American Rodent ia. 

 The group is represented throughout the northern and middle portions of the 

 northern hemisphere, and is not found elsewhere. In the present paper, 

 three species are provisionally recognized as North American and as distinct 

 from their nearest Old World allies. 



ARCTOMYS MONAX (Linn.) Schreber. 

 Woodchuck. 



Mas monax Linnaeus, Syst. Nat. lOtli ed. i, 1758, 00; 12th ed. i, 81 (based wholly on Edwards's descrip- 

 tion anil figure of a specimen from Maryland).— Pallas, Nov. Spec. Glires, 1778 (in part 

 only). — Bodd^rt, "Elench. Anim. i, 1784, 105." 



Glis monax Erxleben, Syst. Anim. 1777, 361 (in part only). 



Arctomys monax Schreber, Siiuget. iv, 737. — Shaw, Gen. Zoiil. ii, 1808, 117. — F. Cuvier, Diet, des Sci. 

 Nat. xxix, 1823, 162.— Warden, Descrip. des Etats-Unis, v, 1820, 627.— Desmarest, Nouv. 

 Diet. d'Hist. Nat. xix, 1818, 314 ; Mam. 1822, 328 (in part only).— Sabine, Trans. Linn. Soc. 

 xiii, 1822, 582.— Harlan, FauD. Amer. 1825, 158— Godman, Amer. Nat. Hist, ii, 1826, 100 — 

 I. Geoefroy, Diet. Class. d'Hist. Nat. x, 1827, 186. — Hamilton-Smith, Griffith's Cuvier's 

 An. King, iii, 1827, 170 (with plate); v, 1827, 244.— Richardson, Fann. Bor.-Amer. i, 1829, 

 153 (compiled, chiefly from Godman). — Fischer, Synop. Mam. 1829, 342. — Emmons, Quad. 

 Mass. 1840, 64. — De Kay, New York Zoiil. i, 1842, 6*, pi. xxi, fig. 4. — Thompson, Nat. Hist. 

 Vermont, 1842, 44.— Wagner, Suppl. Schreber's Siiuget. iii, 1843,259 (in part).— Schinz, 

 Syn. Mam. ii, 1845, 01.— Audibon & Bachman, Quad. N. Amer. i, 1849, 17, pi. ii. — Giebel, 

 Siiuget. 1855,629 (iu part ouly ; includes all the American species). — Kennicott, Trans. III. 

 State Agr. Soc. i, 18E5, ."79; U. S. Pat. Off. Rep. Agr. 1856 (1857), 82, pi. x.— Baird, Mam. 

 N. Amer. 1857, 339, pi. xlix, lig. 1 (skull ). — Thomas, Trans. 111. State Agr. Soc. iv, 1860, 657. — 

 Ross, Edinb. New Phil. Journ. xiii, 1801, 162; Canad. Nat. and Geol. 1861, 434; Nat. Hist. 

 Rev. 1862, 274. — Maximilian, Arch, f Naturgesch. 1861, 93.— Allen, Bull. Mus. Comp. Zoiil. 

 i, 1869, 226 (Massachusetts); Proc. Bost. Soc. Nat. Hist, xiii, 1870, 190 (Iowa) ; xvi, 1874, 

 294.— Cope, Proc. Amer. Phil. Soc. Phila. xi, 1869, 173 (fossil; bone-caves, Virginia).— Gil- 

 pin, Proc. and Trans. Nova Scotia Inst. Nat. Sci. ii, pt. iii, 1870, 16. — Adams, Field and For- 

 est Rambles, 1873, 100, 296 (New Brunswick). 



