156 CALIFORNIA ACADEMY OF SCIENCES. 



Icqytes auratus) where the other one is bright red (C. 

 eafer). The ruby-crowned kinglet (Regulus calendula) 

 has a cap of scarlet while in the golden-crowned kinglet 

 (R. satra,paj it is orange and yellow. The meadow-lark 

 of iSouth America (Sturnelia defilippii) is rose-red where 

 the North American species (S. -magna) is yellow. 



Having now cited instances of different genera of 

 the same family and different species of the same 

 genus in which red and yellow are correlative, let 

 us examine some of the closer genetic relationships. 

 The Arizona hooded oriole (Icierus cucullatus nelsoni) is 

 colored yellow, varying from saffron to gamboge. In 

 the hooded oriole {I. cuoullatus) the color is "orange or 

 dull orange red,"* while in the fiery oriole (/. cucullatus 

 igneus) it is " intense orange-red, sometimes almost scar- 

 let." The male redstart (Setophaga ruticilla) is marked 

 with rich orange-red, the same areas in the female 

 being yellow. In the genus Sphyrapicus and also in 

 Melanerpes, the markings are largely bright scarlet, but 

 supplemented by yellow, as if a part of the color had 

 been intensified by sexual selection, for example, and 

 the rest left unaffected. In the winter plumage of the 

 red-winged blackbirds the shoulder patch is yellow 

 instead of red. The house finch (Garpodacus mexi- 

 canus frontalis) when kept in captivity loses its bright 

 red tints, which are replaced by yellow. The same is 

 true of the crossbills (Loxia,), and would probably be 

 found to hold good for Pinicola and Leucosticte. 

 Canaries fed upon cayenne pepper turn red, although 

 this may possibly not be a converse instance. 



I have now given a considerable number of examples 

 covering all degrees of genetic affinity, of this correla- 

 tion of red and yellow. One of the strongest points in 

 favor of the validity of this correlation as an explana- 



* Ridgwaj'S Manual. 



