1540 Univi rsity of California Publications in Zoology I V( " • ln 



in desertorum. The pelage of this example is slightly harsher, 

 however, and 1 he skull is as in intermedia. These Vallevista wood 

 rats average smaller than intermedia proper, in this respect again 

 resembling the topotypes of gilva. 



The name gilva was applied (Rhoads, 1894, p. 70) to a white- 

 footed wood rat from Banning. Our series of twenty-five from 

 thai locality are thus topotypes. They hear out the single 

 assigned character (if gilva (as compared with inh rrrn dia i . 

 namely, general paleness of coloration. They show in addition 

 an average smaller size than San Diego County intermedia, a 

 slight resemblance to desertorum. An analysis of the color char- 

 acters shows also in all respects an approach to desertorum: As 

 compared with intermedia there is less of the black admixture 

 mid-dorsally ; the brown tones are paler, more huffy; vent rally 

 the white is more extensive, in other words, the plumbeous occu- 

 pies a less space on the individual hairs, and there is more 

 frequently a pure white pectoral patch; the upper side of the 

 tail is less black, more brownish. Contrary to Goldman's state- 

 ment i 1910, p. 15 thai cranially gilva is like intermedia, we find 

 thai Banning old adults have visibly smaller and lighter skulls 

 than inh run dia from t he vicinity of San Diego, and t he rostrum 

 and nasals are shorter. Thus far the resemblance is towards 

 desertorum, hut the audita! bullae are notably smaller than in 

 thai form, and no larger than in intermedia. 



Cabezon, farther down the San Gorgonio I'ass towards the 

 desert proper, furnishes twenty-three examples for our study. 

 These are apparently identical in color with the Banning series. 

 and hence the same general remarks apply. Cranially, too. the 

 two series are practically alike. In measurements, the Cabezon 

 males are larger, and the females are smaller, respectively, than 

 in the Banning animals. These differences are likely therefore to 



Pig. A (mi opposite page). Diagram showing individual ami geographic 



variation in total length (in millimeters) of certain adull white footed w I 



rats. Solid lines, males; broken lines, females; figures at left and right 

 of these lines, respectively, indicate numbers of individuals measured; 

 length of lines shows range of individual variation; points connected by 

 solid and broken lines, respectively, mark positions of averages. Note 

 general reduction in the dimension geographically from the San Diegan 

 district (at left) through the San Jacinto region to the desert. 



