926 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 
ally to the eyes. Generally the feet are wholly intense black, but are some- 
times more or less mixed with gray. In one specimen (No. 5603), the fore 
feet are about one-half gray and one-half black, the gray and black being 
intermixed in irregular patches; the hind feet of the same specimen are 
mostly black. In other respects than those above noted, the series of eleven 
specimens before me is quite uniformly colored. 
A. pruinosus differs from the other American species of Arctomys in 
being much larger than either, and in its wholly different coloration. In 
respect to cranial characters, it differs from A. monax not only greatly in the 
size of the skull but in the posterior convergence of the molar series, in this 
latter respect agreeing with A. flaviventer. It differs, however, quite markedly 
from both A. monax and A. flaviventer in respect to the form of the anterior 
border of the frontals. The suture separating the frontals from the nasals, 
intermaxillaries, and maxillaries forms a nearly straight line in A. prucnosus, 
while in both A. monax and A. flaviventer the nasals extend considerably 
beyond the intermaxillaries, while the latter also extend beyond the maxilla- 
ries. Hence, in A. pruinosus, the frontals terminate more anteriorly and in a 
nearly straight line, instead of being deeply and irregularly hollowed, as in 
A. monax and A, flaviventer, in which only an angular portion extends for- 
ward laterally between the intermaxillaries and nasals and the edge of the 
orbits. 
In size and coloration, A. prauinosus bears a much closer resemblance to 
the A. marmota of Europe than to either of the other American species, 
especially in coloration. A. pruinosus, however, has, like the other American 
species, a rudimentary thumb, with a small but distinct flat nail, which is 
wholly wanting in A. marmota. A. pruinosus has, however, rather the longer 
tail, and is larger. The skulls of the two also present several points of resem- 
blance, particularly in the straight or nearly straight suture between the 
frontals and the nasals, intermaxillaries, and maxillaries. 
The Hoary Marmot was first described by Pennant* in 1781, from a 
specimen (as Richardson tells us) in the Leverian Museum, said to have been 
brought from Hudson’s Bay. ‘That specimen”, adds Richardson, ‘is now 
*« Marmot. With the tip of the nose black; ears short, and oval; cheeks whitish: crown dusky 
and tawny: hair in all parts rude and long; on the back, sides, and belly, cinereous at the bottoms, 
black in the middle, and tipped with white, so as to spread a hoariness over the whole: legs black: 
claws dusky: tail full of hair, black and ferrnginous. Size of the preceding [Maryland Marmot]. 
Inhabits the northern parts of North America.” 
