298 CALIFORNIA ACADEMY OF SCIENCES. 



GENUS LOXIA. THE CROSSBILLS. 



(8) Adult male more conspicuously colored than 

 female; young with a peculiar first plumage, but more 

 or less similar to adult female. 



Prevailing colors, red, yellowish green, olivaceous, 

 grayish, white. 



Like the preceding, these birds have descended from 

 a gray streaked ancestor, in fact, probably from the 

 same species. The colors are the result of sexual selec- 

 tion, apparently, the yellow correlative of the red having 

 been transmitted more or less to the females and young 

 males. It is probable that Coccothraustes, Pinicola, 

 Carpodacus and Loxia all have originated from the same 

 stock, the first genus alone retaining the yellow color in 

 the adult male plumage, the others acquiring the red 

 correlative. 



The white wing bands of L. leucoptera are apparently 

 discriminative recognition marks. 



GENUS LEUCOSTICTE. THE LEUCOSTICTES. 



(4) Sexes alike, changing color with the season; 

 young differ from adults at any season. 



Prevailing colors, black, brown, gray, white, red 

 (generally rose). 



The structural affinity and general character of the 

 colors of this genus ally it with Pinicola, etc., although 

 the sexes do not differ in plumage, and the young are 

 plain brown, less conspicuously streaked, thus differing 

 from the genera previously considered. It is difficult to 

 determine what factors besides sexual selection have 

 produced the colors of this genus. Geographical isola- 

 tion has had some influence in the origination of specific 

 differences, although probably not the only factor. 



