374 University of California Publications in Zoology [Vol. 10 



Springs, is, in its pale and conspicuously silvery hue, unequivo- 

 cally scotti. In February. 1912, the senior author saw at Palm 

 Springs five skins of foxes recently trapped at the rocky base of 

 the foothills close by; these, also, were readily recognizable as 

 the pale scotti, rather than calij "ornicus. 



The skulls furnish the best basis for determining individuals. 

 Those from Palm Springs and Carrizo Creek are very close to 

 the average of scotti. One from Cabezon, however, and another 

 from Palm Canon, although also on the desert side, are much 

 more nearly calif ornicus. The relative inflation of the audita! 

 bullae is a particular feature of uneven variation, and on this 

 character alone segregation by locality shows no geographical 

 orderliness. In other words there is no regularly progressive 

 change in the character from point to point in a direct line from 

 one faunal area into the other. 



Again, as with the desertorum group of wood rats, the foxes 

 of the San Jacinto region appear to show the results of continued 

 interbreeding of two low-zone races of animals whose habitats 

 here abut. The line of faunal mergence is so narrow that there 

 is no room for gradual blending as is usually exhibited between 

 races when the faunal transition occupies a much wider extent 

 of country (as compared with the powers of locomotion of the 

 species concerned). Instead, the intermediates are heterogeneous 

 in their exhibition of characters, and are thus more in the nature 

 of hybrids than geographic intergrades, if each term be used in 

 the sense in which it is commonly employed in systematic mam- 

 malogy. In the San Jacinto foxes it is clearly just as much 

 geographic intergrading in a real sense as if all the animals from 

 any one point along a line from one habitat to the other were 

 uniform, and as if similar representations from the series of 

 points aligned themselves in even gradation from one extreme 

 to the other, instead of there being a conspicuous irregularity 

 in all respects, as is the case. 



Salient facts are : the Colorado River series and a series from 

 the coast district of California are each uniform within narrow 

 limits of individual variation; the San Jacinto series is widely 

 variable, including extremes referable to each subspecies and 

 examples showing various combinations of characters. 



