G L I R E S. 



35 



Mr. Peale states : 



" Muskrats, the name by which these animals are best known in 

 the United States, were seen by the Expedition, in Oregon. Along the 

 Columbia River they are quite common, but it was remarkable that 

 all the specimens seen there, were smaller than those found on the 

 Atlantic coast. 



" The only specimen preserved, was one obtained on the Willa- 

 mette River, which having been destroyed by the exposure incident 

 to a long journey on pack-horses, prevents our showing any specific 

 difference, which the difference in size inclines us to suspect." 



2. Family ARCTOMURIDiE. 

 1. Genus ARCTOMYS, Schreber, Saugtb. IV, p. 721 (1792). 

 1. Arctomys monax {Linn.). The Ground Hog. The Hoary Marmot. 

 Mus monax, Linn. Syst. Nat. I, p. 81 (1766). 



'IIi'.s empetra, Pallas, Nov. Sp. Quad. e. Glirium Ordiae, p. 75 (1777). 

 Arctumys monax et Arctomys cmpetra, AuCT. 



Rich. Faun. Bor. Am. Mamm, Plate IX; And. and Bach. Quad. 

 U. S. Plate II, Oct. ed. (pi. 1). 



Dr. Pickering mentions this animal as having been observed in 

 Oregon, and thinks it the same specifically as the common species of 

 the United States. There being no specimens in the collection, we 

 introduce it for the purpose of citing his observations, which occur 

 under date of 7th of June, 1841 : 



"Arrived at Fort Okanagan just too late to see some specimens of 

 ' the Siffieur,' which w^ere partly cooked, and I was at the time much 

 disposed to regret it, under the impression that it was a species with 

 which I was not acquainted. Three specimens were, however, brought 

 in by an Indian the next day, and proved to be identical with the 

 Wood Chuck of the United States [Arctomys monax), so far as I could 

 remember the character of the latter, or certainly presenting no strik- 

 ing difference. 



"General form, thick and heavy; ears, small and rounded; tail, 



