152 CALIFORNIA ACADEMY OF SCIENCES. 



which the black and white are about evenly distributed 

 in streaks over the body. Among the woodpeckers a 

 considerable number have black and white markings in 

 about equal proportions. The general black color of the 

 lark bunting (Calamospiza melanocorys) is relieved by a 

 broad white patch on the wing. The bobolink (Doli- 

 chonyx oryzivorus) has almost as much white and buff in 

 its make-up as it has black. The shiny-crested flycatcher 

 ( 'Phainopepla nitens), although for the most part black, 

 has the inner webs of the primaries white. Perhaps 

 the most remarkable case, where no utility can be con- 

 ceived, is the white-necked raven (Corvus cryptoleucus), 

 which has the feathers all around the neck pure white 

 at the base. It would be difficult to understand how this 

 could be an advantage, being entirely concealed by the 

 overlapping tips of the feathers. The tendency toward 

 albinism is common among the crows, while in the mag- 

 pies (Pica) and the flute bird of Australia (Gymnocitta) 

 white figures largely in the plumage. 



As a recognition of some sort of interdependence be- 

 tween black and white, as they exist among birds, I 

 would suggest that they be termed Cognate Colors. 



Although, as before stated, there are no exclusively 

 white birds in North America, the winter dress of the 

 ptarmigans (Lagopus), approaches very close to this. In 

 the following species white is the prevailing color: 

 Elanoides forficatm. Bubo virginianus arcticus. 



Elanus leucufus. Nyctea nyctea. 



Falco islandus. Plectrophenax nivalis. 



Scotiaptex cinereum lapponi- Plectrophenax hyperboreus. 



cum. 



In no instance is a species colored in some uniformly 

 pale shade approaching white, the aiithesis of the dark 

 color of Sayornis nigricans. There are thus only about 

 four species of ptarmagin (Lagopus), which are almost 



