Vol IX, pp. 117-128 July 2, 1894 



PROCEEDINGS 



BIOLOGICAL SOCIETY OF WASHINGTON^ 



ABSTRACT OF A STUDY OF THE AMERICAN WOOD 



EATS, WITH DESCRIPTIONS OF FOURTEEN 



NEW SPECIES AND SUBSPECIES OF 



THE GENUS NEOTOMA. 



BY DR. C. HART MERRIAM. 



The following brief abstract of a study of the North Ameri- 

 can Wood Rats and Desert Rats, with descriptions of a dozen 

 new forms from Mexico and the western United States, based on 

 the rich collections of the United States Department of Agricul- 

 ture, is here published in advance of a more formal pa})er on the 

 group. Tlie genus Ncotomd is here restricted to the species in 

 which the crown of the last lower molar is made up of two trans- 

 verse loo})s; the species having the crown of this tooth shaped 

 like the letter S are transferred to the genus riijssopJujrus of 

 Ameghino, j^i'evioijsly known from a single fossil species from 

 South America. As thus restricted, the genus Nrofovui is divided 

 into two subgenera, Neotmna proper and Tcononut, which are 

 comj^lementary in their geographic distribution, Ncotoriia proper 

 being Sonoran or Austral, while Teoiuyma is Boreal. It is con- 

 venient to subdivide the former into four minor groups, none of 

 which is worthy of the distinction of subgeneric rank. These 

 groups may be designated, from a typical species in each, as fol- 

 lows: (1) the /c»ror/ojy group ; (2) the viiravVr/;/^' group ; (3) the 

 desertoruni group, and (-4) the arhotuv group. 



Subgenus neotoma Ord, 1825. 



Type, Neotoma floridanu Ord, from Florida. 



Tail commonly round, scant-haired and tajjering, but in one species mod- 

 erately bushy ; hind feet small or moderate. 



