KEY TO LAND MAMMALS OF NORTHEASTERN NORTH AMERICA 95 



Mus rattus Linnaeus Black rat 



1758 [Mus] rattuB Linnaeus, Systeraa naturae, cd. 10. 1:61. (Sweden) 

 Blue black, darker on the back, more slaty ou the belly. Total length, 400 

 (15i); tall vertebrae, 215 (8^); hind foot, 37 (l/n). (r4ttus; Lat., a rat) 



The black rat was formerly widely spread in the eastern United 

 States. It is now rapidly disappearing before the larger and stronger 

 brown rat. This animal occurs still in central Massachusetts, but with 

 this exception I know of no localities where it is now found abundantly 

 in the northeastern United States. 



Mus decumanus Pallas House rat 

 1778 Mus decumanus Pallas, Nov. ep. quadr. glir. ord. p. 91. (Russia) 



Brownish above ; grayish teneath; tail scaly, clothed with short stiff hairs, not 

 distinctly bicolor. Total length, 400 (15j) ; tail vertebrae, 180 (7J) ; hiud foot, 

 45(11). (deeumdnus; Lat., a tithe gatherer) 



The house rat is abundant and well known throughout North 



America. 



Genus Reithrodontomys Giglioli 



1873 U e i t h r o do n t o m y 8 Giglioli, Richer, intorn. alia distrib. geogr. 

 gener. p. 60. Type Mus lecontii Aud. and Bach. 



Like Peromysous except that the face of each upper front tooth is marked 

 by a conspicuous longitudinal groove. (Rei throd6ntomys; Gk., channel tooth 

 mouse) 



The genus Reithrodontomys is confined to North America. 

 It reaches its greatest development in Mexico and the southwestern 

 United States, where it is represented by 15 or more forms. Only one 

 species occurs within our limits. 



Reithrodontomys lecontii (Audobon and Bachman) Harvest mouse 



1842 Mus lecontii Audobon and Bachman, Journ. Acad. aat. sci. Phila- 

 delphia. 8:307. (Georgia) 



1895 Reithrodontomys lecontii Allen, Bull. Am. mus. nat, hist. May 

 21, 1895. 7:116. 



Light brown above, varying much in exact shade; whitish beneath. (Iec6n- 

 t i i ; name from that of John LeConte) 



The harvest mouse is common throughout the southeastern United 

 States. Three races are now recognized : R. lecontii dickinsoni 

 Rhoads from Florida ; R. lecontii lecontii from the lower 

 austral zone, and th,e following : 



