SCIUKID2E— AKCTOMYS FLAVIVENTElt. 921 



ARCTOMYS FLAVIVENTER Aud. and Bach. 



Rocky Mountain Marmot. 



Arctomys flamventer Audubon & Bachsian, Proc. Acad. Nat. Sci. Phila. 1841, 99; Journ. Acad. Nat. Sci 

 Phila. viii, 1842, 309 ; Quad. N. Am. iii, 1853, 1U0, pi. cxxxiv. — Wagner, Wiegnaaun's Archiv. 

 ii, 1843, 45— SCHINZ, Syn. Mam. ii, 1845, 63.— Baird, Mam. N. Am. 1857, 343, pi. xlvii, fig. 1 

 (skull).— Suckley, Nat. Hist. Wash. Terr. pt. iii, 1859, 99, 124.— IIayden, Trans. Am. Phil. 

 Soc. Phila. xii, 1863, 146.— Meriuam, U. S. Geol. Snrv. of Terr.Cth Auu. Rep. 1872 (1873), 664.— 

 Allen, Proc. Bost. Soc. Nat. Hist, xvi, 1874, 294; Bull. Essex lust, vi, 57, 66. — Couks &, 

 Yarrow, Wheeler's Expl. and Surv. W. of 100th Mcrid. v, Zoiil. 1875, 123.— Grinnell, Lud- 

 low's Black Hills of Dakota, 1875, 82. 



Specific chars. — Length to base of tail about 17.00 to 18.50; of (ail 

 to end of vertebrae 6.50 to 7.25 ; of tail to end of hairs 9.00 to 10.00. 

 Above mixed gray, fulvous, and reddish-brown ; below yellowish or golden, 

 varying to rufous. The general color also varies, to wholly black or brown- 

 ish-black, as in A. monax. Sides of the nose and chin whitish-gray; top of 

 the head dark reddish-brown ; tail with the hairs at base pale reddish-brown 

 to black, broadly tipped with yellowish-brown or rufous ; feet yellowish- 

 rufous, strongly varied with black. Ears rather small, thinly haired, yellow- 

 ish-brown, sometimes edged with darker. Tail long, round, full, and bushy, 

 with the hairs fully one-half to more than one-half the length of the head 

 and body. 



The specimens before me chance to be quite uniform in coloration, but 

 melanistic specimens are of frequent occurrence. A specimen from Fort 

 Massachusetts, N. Mex., is everywhere dark brownish-black, slightly varied 

 with gray. At Montgomery, Colo., where this species occurs in great abun- 

 dance, and where I have seen a dozen or more sitting on the rocks at one 

 time within easy rifle range, generally several black ones were to be seen 

 associated with the others, as well as others more or less blackish. Usually 

 the abundant under fur of the dorsal surface is dusky at base, then clear 

 pale fulvous, passing into golden at the extremity. The overlying longer hairs 

 are conspicuously white-tipped, with a broad subterminal bar of reddish- 

 brown. The under surface is very thinly haired, with no under fur. The 

 hairs are here dark reddish-brown at base, broadly tipped with fulvous, the 

 tint varying in different specimens from pale yellowish to bright rufous. The 

 tail is usually hided yellowish-brown at the surface, the hairs deepening into 

 dark reddish-brown or blackish basally. The rump is generally clear yellow- 

 ish, varied with the whitish-yellow tips of the longer hairs, and hence lighter 



