NYCTICORAX. 169 



birds have ornamental feathers which looks as if they were fully adult, 

 and therefore they may be birds of the second year, as it is quite evident 

 that the grayer plumaged ones are very old and perfect in livery. 



"The white streak down the throat is often absent or reduced to a few 

 spots. It appears to be absent equally in quite young birds and in old 

 ones also, and it may be the result of inherent melanism in the species. 



"The white form is exactly similar in size to the gray form, and, when 

 adult, has the same ornamental plumes. In the Pacific islands the two 

 forms appear to interbreed, and produce white young ones mottled or 

 streaked with slaty gray. I have been unable to recognize any of the 

 many forms into which the reef heron has been subdivided by naturalists. 

 Some birds are larger, as will be seen by the measurements of the tarsi 

 given in detail below, and these larger birds have a slightly longer wing 

 and a heavier bill, but no specific distinctions can be founded on these 

 variations, which are very slight." (Sharpe.) 



"The color of the soft parts is excessively variable. In the adult the 

 bare portion of .the tibia varies from dark grass-green to greenish plumbe- 

 ous ; the back and sides of the tarsus and the greater part of the toes are 

 generally pea-green, sometimes duller, sometimes yellower; the front of 

 the tarsus and the first joint of the mid toe black, but sometimes these 

 parts are green, only patched or mottled with black, and sometimes the 

 black extends along the ridges of all the toes; the color of the bill and 

 bare skin in front of the eye varies from sienna-brown to chocolate ; some- 

 times the bill is a sort of light mahogany color, and the bare skin a 

 sort of greenish brown; usually the bills are yellowish at the tips; the 

 lower mandible is generally lighter, sometimes brownish horny, sometimes 

 yellowish horny; and in the breeding-plumage the whole lower mandible 

 becomes apparently a very decided, though dull, yellow; the irides vary 

 from bright to deep yellow. I suspect, though we have not been able to 

 work it out, that these differences in color are due both to age and to 

 season." (Hume.) 



"Quite common along the reefs. The young were met with on various 

 occasions far inland along fresh-water streams, but we never found fully 

 mature birds in such localities." (Bourns and Worcester MS.) 



So far as observed, this species is solitary and found only on rocky 

 shores, usually where coral flats are exposed at low tide. 



Genus NYCTICOKAX Forster, 1817. 



Bill stout; legs rather short; tarsus about equal to middle toe with 

 claw and little longer than exposed culmen ; tarsus covered with hexagonal 

 scales; head decorated with two or three long, slender, nuchal plumes 

 and a full crest. 



