Vol. VIII, pp. 55-70 June 20, 1893. 



PROCEEDINGS 



OF TIIF. • '" 



BIOLOGICAL SOCIETY OF WASHINGTON., _ 



\'- 



DESCRIPTION OF A NEW WHITE-FOOTED MOUSE 

 FROM THE EASTERN UNITED STATES. 



BY GERRIT S. MILLER, Jr. 



A critical study of over five hundred specimens of Sitoni_ys 

 collected in the northeastern United States and adioinino- R>ritish 

 provinces leads me to the conclusion that two distinct though 

 somewhat closely related animals are at present confused under 

 the name of Sltomys americnntis. The two forms ma}' he distin- 

 guished by the following diagnoses : 



Ratio of tail vertebrte to total length ranging from 40 to 47.9 ; 

 pencil, 2 mm. to 5 mm.; tail often not sharply bicolor; young 

 usually i)assing directly from the plumbeous first coat to the 

 russet-brown pelage of the adult, which is thus present in the 

 great majority of specimens. .... americnnirs. 



Ratio of tail vertebra) to total length ranging from 4G.5 to 53. G ; 

 pencil, 4.4 mm. to 11 mm.; tail always sharply l)icolor; 3^oung 

 ahvays passing through a gray phase between the plumljcous 

 first coat and dull yellowish brown pelage of adult, wliich is 

 tlius com})aratively seldom met with. . . . canadensis. 



Sitomys americanus canadensis subsp. nov. 



JTcsperomijs myokles Baird. Mam. N. Am., 1857, 472 (probably in part 

 only), not Cricetus myoides Gapper. 



Sulisp. Ch. Somewhat larger than Sitomijs america.nus (Kerr), 

 witli longer, more hairy tail, and duller, less russet coloration ; 



S— Biol. Soc. Wash., Vol. VIII, 189.i, (55) 



