RODENTIA SCIURINAE ARCTOMYS FLAVIVENTER. 



343 



List of specimens. 



To end of outstretched hind legs, 20 inches. 



To end of outstretched hind legs, 18 inches ; longest fore claw, .60 ; hind claw, .42. 



AECTOMYS FLAVIVENTER, Bachman. 



Yellow-Footed Marmot. 



Jlrclomysjlaviventer, AUD. & BACH. Pr. A. N. Sc. Phila. I, 1841. IB. J. A. N. Sc. Phila. VIII, 11, 1842, 309. IB. 



N. Am. Quad. Ill, 1853, 160; pi. cxxxiv. 

 WAGNER, in Wiegmann's Archiv, 1843, II, 45. 



Sp. CH. Size of common woodchuck. Above, yellowish brown, somewhat grizzled with gray. Under parts of body and 

 tail, and the legs all round, inside and out, reddish chestnut. 



A skin from the Black Hills, obtained by Dr. Hay den, is of very large size. The under parts, 

 with the legs all round, are uniform chestnut brown, or dark chestnut, to the roots of the hairs. 

 The upper parts are rusty yellowish, except in the middle portion of the lumbar region, where 

 they are paler, and grizzled somewhat with dark brown, owing to a subterminal annulation of 

 this color near the tips of the long hairs. The top of the head is uniform dark brown, nearly 

 black ; the top and sides of the muzzle are reddish ; the under part of the chin whitish. The 

 tail is colored much like the belly ; the hairs becoming dark brownish towards the roots. 

 Length of skin, stretched, 22 inches ; tail vertebrae, 8 ; with the hairs, 30. 



The feet are wanting in part, or else so much mutilated as not to admit of a satisfactory 

 description. The skull of this animal has fortunately been preserved in good condition, and 

 presents some very characteristic features, as compared with that of A. monax. The muzzle is 

 remarkably short and broad, owing to the extent to which the intermaxillaries enter into its 

 upper surface. This is connected with a much greater proportional size of the upper incisors, 

 which require more space for their accommodation. There is a more than usual depression or 

 concavity on the frontal bone between the orbits. The upper molars again are rather smaller 



