Vol. XVII, pp. 139-146 July 14, 1904 



PROCEEDINGS 



OF THK 



BIOLOGICAL SOCIETY OF WASHINGTON 



NEW AND LITTLE KNOWN KANGAROO RATS OF 

 THE GENUS PERODIPUS. 



BY C. HART MERRIAM. 



Tlic Icangaroo rats, a group p'.^culiar to the arid parts of North 

 Ainrrica, arc represented l)y three genera — Dipodomys, Perodlpus, 

 and iWrmdipodops. The latter is very much more distinct from 

 the others than they are from each other. Dipodomys and 

 Microdipodops liave l:)een previously studied, and the species 

 have heen pul)lished, luit up to the present time only a l:)egin- 

 ning has heen made in working out the species of Perodipus. 

 A study of tlie rich collections of the Biological Survey leads 

 me to recognize nine new forms, which are here descrilsed. One 

 of these, named ingens, is a very large animal for a kangaroo 

 rat, equaling in size Dipodomiix xprrtabilis from Arizona and 

 New Mexico. It inhaliits the liot Carrizo Plain and adjacent 

 southern end of the San Joaquin Valley in California. Another 

 species, P. inicrops, from Lone Pine, Owens Valley, is the 

 smallest of the genus thus far discovered, being smaller even 

 than iirdi and columbianiii^. 



A curious feature connected with the kangaroo rats of this 



genus is that most of the species and subspecies may be arranged 



in four groups according to size: The small onU group, the 



slightly larger montanm group, the decidedly larger agills group, 



25— Proc. Biol. Soc. Wash. Vol. XVII, 1904. (139) 



