312 california academy of sciences. 



Genus Sporophila. The Seedeaters. 



(7) Adult male more conspicuously colored than fe- 

 male; young like female, but young male generally 

 intermediate in plumage between female and male. 



Prevailing colors, black, white, olive, brown, gray. 



This genus is apparently becoming melanistic in ac- 

 cordance with the laws of growth and specialization. 

 The colors are doubtless useful for purposes of recogni- 

 tion. 



Genus Euethbia. The Grassquits. 



(7) Adult male more conspicuously colored than fe- 

 male; young like female, but young male generally 

 intermediate in plumage between female and male. 



Prevailing colors, black, white, gray, yellow, olive 

 green, rufous. 



The yellow and black of this genus are refined from 

 the olive green of the back. The presence of black upon 

 the breast instead of the back would seem to be in oppo- 

 sition to the rule that the excess of sunlight has caused 

 the greater part of pigment to seek the back, but may 

 perhaps be interpreted in harmony with this. AVhere 

 black is the result of an intensified brown or blue it ap- 

 pears to be caused simply by the amount of pigment 

 matter crowded into a given space. If, on the other 

 hand, the system of a bird gives rise to definite black 

 pigment, the color is not dependent quite so exclusively 

 upon the amount. In the present instance two pigments, 

 yellow and black, have apparently crowded together upon 

 the back, producing the olive green color, while upon 

 the breast they have been separated. 



The tendency of the genus is towards the assumption 

 of a completely melanistic plumage. 



Genus Spiza. The Dickcissel, etc. 



(8) Adult male more conspicuously colored than fe- 



