222 CALIFORNIA ACADEMY OF SCIENCES. 



DcndroicK pensylva nicn . Pusscrimi . 



DcnJroica castnnea. Spiza. aviericanu. 



Deadroicu striain. Molothrus uter. 



Pirangu ladovlciu aa. Pyrocejjhdus rubineus. 



Piruvjia rubra. Sphyrupicas vorius. 



Sj)lmis lav'vencei. Melanerpes caroliaufi. 



Pipilo erythroplifhcdiiitin Sialia. 



This class, like the preceding, is made up of brightly 

 colored species without exception. The colors are sexual 

 ornaments, but in every instance have been partly 

 acquired by the female, which thus stands in an inter- 

 mediate position between the generalized plumage of 

 the young and the specialized plumage of the adult, 

 marking three stages of evolutionary progress. Thus 

 the colors of the female western tanager (Pirangu 

 ludoviciana) lack the brilliancy and purity of the hues 

 of the male, while the young, in their first plumage are 

 streaked above and below. The summer tanager (P. 

 rubra) is colored in a corresponding manner, as is also 

 the scarlet tanager (P erythromelas). A. specimen of 

 this species in the collection of the National jNIuseum — 

 a male in full plumage — is colored a deep yellow, with 

 black wings, entirely different from the greenish yellow 

 of the female. This is proably an instance of reversion 

 to an earlier plumage, or may possibly be simply the 

 correlative of tiie red pigment, due to some derangement 

 in the bird's system. The adult female of Lawrence's 

 goldfinch (Spiims lavreaa'A) is without the black of the 

 head, and with all the colors somewhat duller, while the 

 young are plain dusky with a little yellow on the wings 

 and a decided tendency towards a streaked plumage. 

 In the indigo bunting (PaMerin.a cyaaea) the bright blue 

 of the male is replaced by a dull brown, while the plum- 

 age of the young is like that of the female, but streaked 

 above and below. The bluebird (Sialia sialis) is a fa- 



