1913] GrinncU-Swarth: Birds and Mammals of San Jacinto 345 



bella" (Bangs, 1899, pp. 66, 67). Judging from those of the 

 ascribed characters which are at all pertinent, the type specimen 

 was nearest desertorum. Moreover, Goldman (1910, p. 78) syn- 

 onymizes the name bclla under desertorum. 



The thirteen specimens from Palm Canon are small, like 

 desertorum, with small skulls just like the Whitewater ones, but 

 are rather coarser pelaged and are dark, being almost facsimiles 

 of Banning and Cabezon examples of corresponding age. 



The series of ten adults and young from the vicinity of Dos 

 Palmos Spring are indistinguishable in respect to size, quality 

 of pelage, and coloration, from desertorum. Cranially they are 

 also duplicates save in one respect, that of audital bullae, which 

 are plainly less inflated. 



It is shown by the foregoing array of facts that, in the white- 

 footed wood rats of the San Jacinto area, there are two diverse 

 types on the remoter parts of the opposite sides of the mountains, 

 namely, intermedia on the Pacific side, most typically represented 

 by the specimens from Kenworthy, and desertorum at the desert 

 base, as illustrated at Whitewater, Palm Springs, and perhaps 

 Dos Palmos. The point of emphasis is that our material, as 

 interpreted by us, would seem to establish complete intergrada- 

 tion between the extreme types named. In all respects as enu- 

 merated, we find transition through various intermediate degrees 

 of difference from one extreme to the other. This is not in 

 accordance with currently accepted notions as regards the rela- 

 tionship between intermedia and desertorum (see Goldman, 

 1910) ; but were we without recourse to previous literature, we 

 should unhesitatingly place one form as a geographic race of the 

 other without considering any explanation of our position as 

 called for. 



That extensive intergradation between the above-named forms 

 in the San Jacinto region is a fact, we are confident. The only 

 argument in rebuttal of the subspecific idea is that our inter- 

 mediates are in the nature of hybrids. This contention would 

 find evidence for support in the narrowness of the area occupied 

 by wood rats showing intermediate characters between inter- 

 media and desertorum, and in the manifest lack of uniformity 

 of variation from place to place. 



