72 University of California Publications in Zoology [Vol.10 



Occidi iitalis — larger; coloration brighter; with yellow of under- 

 parts usually more orange; whitish posterior margin of black 

 facial mask, broader. Arizela — .smaller, with much smaller bill; 

 coloration duller, with yellow of underparts less orange; whitish 

 margin posterior to black mask, narrower. 



Occidentals was described from Truckee River, Nevada 

 (Brewster, 1883, p. 159). There are no exact topotypes avail- 

 able, but I have considered a series of eleven breeding birds 

 from Humboldt County, Nevada, as typical of the race. Com- 

 paring these with the Vancouver Island adults I can appreciate 

 absolutely no differences of color or pattern, while the differences 

 in size are too slight to merit recognition by name. Chapman, 

 in commenting upon some yellowthroats from British Columbia 

 (1890, p. 151) also expresses his inability to distinguish between 

 birds from the coast and from the interior. 



There appear to be, however, two races of yellowthroats on 

 the Pacific Coast with differences such as are supposed to dis- 

 tinguish occidt ntalis and arizela. The breeding bird of southern 

 California and southern Arizona is of very bright colors, some- 

 times with the yellow of the ventral surface extending over 

 almosl the entire abdomen and flanks. This bird was designated 

 Geothlypis t. scirpicola by Grinnell (1901b, p. 65; type from 

 El Monte, Los Angeles County, California), a name now rele- 

 gated to the synonomy of G. t. arizela (see Ridgway, 1902, p. 

 672) — which is described as a small, dull-colored form! 



The material at hand points toward the following disposal 

 of these two western races of yellowthroats. as being probably 

 the correct solution of the question : 



Occidentalis — small billed, and duller colored, with the yellow 

 of the throat and breast not extending posteriorly over the 

 flanks and abdomen; whitish posterior margin of black facial 

 musk narrow and rather sharply defined. Range (approxi- 

 mately) from central Nevada and California north through 

 British Columbia (including Vancouver Island) to southeastern 

 Alaska (Swarth, 1911a, p. 101). Arizela thus becomes a pure 

 synonym of occidentalis. 



Scirpicola — with larger bill and brighter colors; yellow of 

 throat and breast brighter, extending over the entire abdomen. 



