198 CALIFORNIA ACADEMY OF SCIENCES. 



constant in their color and I know of no species which 

 is marked with general variable anticryptic colors. Th^ 

 snowy owl (Xyctea nyctea), would come nearer answering 

 the requirements than any other species, but the change 

 in this species is dependent more upon age than sea- 

 son, and it would accordingly not apply. Of (cZ) special 

 anticryptic colors, the belted kingfisher (Geryle alcyon), 

 is a partial example, and the only one with which I am 

 familiar. The colors of this bird are such that they 

 blend, not with the environment of the bird particularly, 

 but with the water and sky as seen by the fish as its foe 

 descends upon it from above. 



(II) Pseiulosematic colors are seldom met with among 

 birds — at least among North American species. Wallace 

 has suggested that many of the plumes and appendages of 

 birds may be used to frighten enemies, but I have been 

 unable to detect any instances of their use for this pur- 

 pose. Ordinarily, when an enemy threatens, a bird will 

 seek safety in flight, rather than try the doubtful experi- 

 ment of frightening a foe by its formidable appear- 

 ance. There are some cases of protective mimicry 

 among birds, although I know of none among North 

 American species. "A most extraordinary case," says 

 Dr. Stejneger,"^ " is that of the Indian, so-called drongo- 

 cuckoo (Surniculus dicruroides), which, as indicated by 

 the name, so exactly imitates the king-crow, or drongo- 

 shrike (Dicrurus), inhabiting the same locality, in size, 

 form and color, that there is required considerable at- 

 tention in order not to confound them, though the ar- 

 rangement of the toes, of course, at a closer inspection 

 is alone sufficient to separate them. This imitation is 

 the more strange since it has even extended to the curi- 

 ously furcated tail, a feature elsewhere entirely unex- 

 ampled among the cuckoos." Further study may bring 



* Riverside Natural History, iv, p. 380. 



