62 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th See. 



turns the tail is usually decidedly the longer. Eremophilus, of 

 the southern deserts, shows still greater extremes of pallid 

 coloration and length of tail. Between eremophilus and cha^ 

 rienturus, where there is a wide gap in distribution except in 

 one limited region, as noted beyond, there can not be traced 

 the nicely graded series of changes found between the other 

 California mainland forms; judging from the imperfectly rep- 

 resentative material here assembled from the southern Sierra 

 Nevada (where apparently the ranges of eremophilus and cha- 

 rienturus closely adjoin), such a condition may be existent in 

 this region. Further collecting here at the proper seasons is 

 necessary to demonstrate this. 



Thus on the whole it is seen that the Pacific coast races 

 of Thryomanes bewicki may be divided into two general 

 groups, of pale colored, long tailed forms in the arid south- 

 western region, and dark colored, short tailed forms in the 

 humid northwestern coast region, with maximums of size at 

 the extreme north and south. In every type of variation, con- 

 necting chains of intermediates may be traced, corresponding as 

 exactly in geographical position as in extent of variation. 

 Drymoecus, as detailed beyond, occupies a central position, 

 almost surrounded by the other mainland forms, and the char- 

 acteristics of birds of this subspecies vary exactly as the con- 

 fines of the several contiguous races are approached. 



The insular forms of Thryomanes bewicki do not exem- 

 plify continuous variation such Ss seen on the mainland. Van- 

 couver Island calophonus, in its comparatively paler browns, 

 shows a departure from the mode that does not accord with 

 the general manner of variation of the species in this region. 

 San Clemente Island leucophrys, in its gray coloration, might 

 be regarded as exhibiting results of the same nature as are 

 shown in the comparatively gray Pipilo maculatus clemenlce 

 of the same island. This theory is upset by the fact that 

 on the closely adjacent Santa Catalina Island (lying directly 

 between San Clemente and the mainland), where Pipilo m. 

 clementce also occurs, the representative form of Thryomanes, 

 T. b. catalincE, is distinguished from the mainland charienturus 

 by slightly darker brown coloration. T. b. nesophilus of Santa 

 Cruz and Santa Rosa islands is again differentiated from cha- 

 rienturus by slightly darker, more rufescent, coloration. 



