Vol. 32, pp. 203-206 December 31, 1919 



PROCEEDINGS 



OF THE 



BIOLOGICAL SOCIETY OF WASHINGTON 



FOUR NEW KANGAROO RATS FROM WEST-CENTRAL 



CALIFORNIA. 



BY JOSEPH GRINNELL. 



Contribution from the Museum of Vertebrate Zoology of the University 



of California. 



Further study of the kangaroo rats of California has led the 

 writer to conclude that there are no good grounds for retaining 

 any longer the supposed genus Perodipus. The presence or 

 absence of the first pedal digit or at least its claw, both of which 

 are only rudiments at best, proves to be an inconstant feature 

 within three of the species. No other characters have been 

 found which seem of generic value ; and on the other hand there 

 are many which occur in all the species with remarkable uni- 

 formity. The kangaroo rats in toto comprise one ideal genus. 

 The following new forms are therefore all described under the 

 older name Dipodomys, irrespective of whether the specimens 

 at hand show five toes on each hind foot or only four. 



Dipodomys jolonensis, new species. 



JOLON KANGAROO RAT. 



Type. — Male adult, skin and skull; No. 29087, Mus. Vert. Zool. ; valley 

 floor one mile southwest of Jolon, Monterey County, California; October 

 18, 1918; collected by J. Dixon; orig. No. 6970. 



Comparative diagnosis. — A broad-faced, normally five-toed, middle-sized 

 kangaroo rat perhaps nearest like its next neighbor on the north, Dipodomys 

 goldmani (Merriam). Differs from goldmani in somewhat larger size, in 

 decidedly larger auditory and mastoid bullae, in narrower interparietal and 

 supra-occipital, in more heavily tufted and crested tail, in dorsal body- 

 color being paler, and in light markings on head and tail being whiter and 

 more extended. Similar to Dipodomys swarthi (Grinnell) in size and cranial 

 features, but general body-color much darker (due to the greater extent of 



41— Paoc. Biol. Soc. Wash., Vol. 32, 1919. (203) 



