KEY TO LAND MAMMALS OF NORTHEASTERN NORTH AMERICA 89 



Genus Arctomys Schreber 

 1780 Arctomys Schreber, Siiugethiere. pi. 207. 



Form stout and heavy; tail short, much less than half as long as body, 

 densely covered with long, rather stiff hairs ; upper cheek teeth five in each jaw, 

 each, except first, with two transverse grooves on crown. (Arctomys; Gk., 

 bear mouse) 



The genus Arctomys occurs throughout the greater part of 

 northern North America, Asia and alpine Europe. It is represented 

 in North America by six or more species, two of which, the well known 

 woodchuck or ground-hog, and a little known animal from Labrador, 

 occur within our limits. 



SPECIES OF AKCXOMYS 



Fur much suffused with reddish and yellowish ; skull long and 



narrow, smooth above A. monax 



Fur slightly suffused with reddish and yellowish ; skull short 

 and broad, with a well developed median ridge over brain 

 case ., A. ignavus 



Arctomys monax (Linnaeus) Common woodchuck 



1758 [Mus] monax Linnaeus, Systema naturae, ed. 10.1 ; 60. (Maryland) 

 1780 Arctomys monax Schreber, Saugethiere. 4 : 737. 



Grizzly gray, varied with chestnut, yellowish and blackish; uuder parts red- 

 dish; skull long and narrow, the top smooth. Total length, 460 (18) ; tail verte- 

 brae, 115 (4i) ; hind foot, 75 (3). (Mtinax; Lat., a hermit) 



The common woodchuck is an abundant animal throughout the 

 Hudsonian, Canadian, transition and upper austral zones in eastern 

 North America from Labrador and Hudson bay south at least to Virginia. 

 Two races probably occur in this region, but their characters are not 

 well understood. The southern form is A. monax monax, the 

 northern A. monax canadensis (Erxleben) (See Allen, Bull. Am. 

 mus. nat. hist. 10 Nov. i8g8. 10:456.) Partly or wholly black indi- 

 viduals are often met with. 



Arctomys ignavus Bangs Labrador woodchuck 



1899 Arctomys ignavus Bangs, Proc. New England zool. club. 28 Feb. 

 1899. 1 : 13. (Black bay, Labrador) 



Dark grizzly gray, little varied with yellowish and reddish; skull short and 

 Iroad, the hraincase developing a well marked median ridge in adult individuals. 

 Total length, 500 (191) ; tail vertebrae, 140 (5J) ; hind foot, 80(3i-) . (ignavus; 

 Lat., inactive) 



The Labrador woodchuck is at present known from Black bay, Labra- 

 dor only. 



