146 CALIFORNIA ACADEMY OF SCIENCES. 



yellow or the blue. It might be that in certain in- 

 stances, especially among tropical birds, that a green 

 color was produced simply by a combination of yellow and 

 blue pigments, in which case we shall have the primitive 

 color of the bird, as indicated either by the young stage, 

 or by the body color of the adult, green, and the special- 

 ized colors, yellow and blue. In general, however, the 

 green is probably either a different pigment, or, as is 

 frequently the case, in olive greens, produced by a com- 

 bination of yellow and black. 



It may be well to consider next each of the primary 

 colors (together with black and white) more particularly. 

 More species are wholly or largely black than any other 

 of the primary shades. The following are exclusively 

 or almost completely black: 



Catharista atrata. Scolexophagus. 



Crotophaga ani. Quiscaius. 



Crotophaga sulcirostris. Progne subis. 



Corvus. Phainopepla nite/as. 

 Molothrus ceneus. 



Still larger is the list of species in which black covers 

 a large proportion but not the entire surface of the body: 



Colinus virginianus citban- Pica 'pica hudsonica. 



ensis. Dolichonyx oryzivorus. 



Pseudogryphiis calif or nianus. Molothrus ater. 



Cathartes aura. Agelaius. 



Uruhitinga anihracina. 8pinus psaltria ine.xicana. 



Campephilus principalis. Sprophila morelletti. 



Xenopicus albolarvatus. Euetheia bicolor. 



Sphyrajncus thyroideus. Galar^iospiza melanocorys. 



A number of species are colored a very dark brown 

 or gray, showing a strong tendency towards black. The 

 list of these is as follows: 



