926 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 



ally in ilic eves. Generally i he feet are wholly intense black, but are some- 

 times more or less mixed with gray. In one specimen (No. 5603), the fore 

 Feel are about one-hall 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.Jlaviventcr. It differs, however, quite markedly 

 from both A. monax and A.Jlaviventer 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. pruinosus, 

 while in both A. monax and A.Jlaviventer 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.Jlaviventer, 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. pruinosus 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 tbe nose black : ears short, ami oval ; cheeks whitish : crown dusky 

 and tawny : hair in all parts rude and long; on the back, sides, and belly, cinereous at the bottoms, 

 I'l i. k in the middle, and tipped with white, so as to spread a hoariness over the whole: legs black: 

 claws dusky: tail lull of hair, black and ferruginous. Size of the preceding [Maryland Marmot]. 

 Inhabits the northern parts of North America." 



