926 



MONOGUAPnS OF NOKTH AMERICAN KODENTIA, 



ally to tlic eyes. Generally the feet are wlioliy intense black, but are some- 

 times more or less mixed with gray. In one specimen (No. 6603), 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 

 l)eing much larger than either, and in its wholly different coloration. In 

 respect to cranial chamcters, 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 

 1 itter respect agreeing with A.Jlaviventer. 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, wiiich 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 : enra nhort, aud oval ; cheeks whitish : crown dusky 

 and tawny : hair in all parts rude and long ; nn the bock, sides, %nd belly, ciuereous at the Iwttunis, 

 black in the middle, and tipped wi.h while, so as to spread a houriness over the whole: logs block i 

 claws dusky: tail full of hair, black and ferrnginons. Size of the prooediog [Maryland Mnrniol]. 

 luliabils the uurtbera parts of North Amuriuo." 





