278 CALIFORNIA ACADEMY OF SCIENCES. 



FAMILY ALCEDINID^E. The Kingfishers. 



Genus Ceryle. The Kingfishers. 



(7) Adult male unlike female; young similar to 

 female. 



Prevailing colors, plumbeous blue, bottle-green, ru- 

 fous, white. 



The colors of C. alcyon are probably a form of aggres- 

 sive resemblance, making the bird inconspicuous from 

 the point of view of the fish. The white throat is doubt- 

 less also a socialistic recognition mark of use in the 

 darkness of the burrow where the nest is always placed. 

 The different American species are closely related in 

 spite of the great discrepancy in size and colors. Mr. 

 Ridgway, in a paper entitled " On some Remarkable 

 Points of Relationship between the American King- 

 fishers,""^ has called attention to this fact. Each of the 

 large species is duplicated in miniature more or less by 

 an allied species or fratercule. There must be some 

 utility in the colors for them to have remained so con- 

 stant in spite of a reduction in size of the species in one 

 case to a half. It seems quite possible that the reddish 

 and green colors would be as invisible to a fish in muddy 

 water as white and blue to a fish in a clear stream, and 

 it is not impossible that the first differentiation in color 

 was dependent upon the clearness of the water in the 

 districts in which the different forms arose. It may also 

 be possible that green and blue are correlative colors 

 just as yellow and red are. Such birds as the green jay 

 (Xanthoura luxuosa), and some of the parrots would seem 

 to give an air of plausibility to this view. In the king- 

 fishers the combination of rufous and green is appar- 

 ently a more primitive one than of white and blue. 



The following facts will prove this: C. superciliosa is 



* BiUl. Ni;tt. Oru. Chib, viii, pp. 59-60. 



