RIIYNCHOPS NIGRA, BLACK SKIMMER. 717 



slight -white terminal margin as far as the fourth or fifth. Secondaries about as in the 

 adults, but their brown portions lighter and duller. Tail white; the greater jiart of 

 the two central rectrices, and the inner webs of the others, with a tinge of dull gray- 

 ish-brown, deepest on the middle pair. 



I once saw a single specimen of this bird on the Potomac River, near 

 Washington. Otherwise my personal observations are confined, up to 

 the present time, to the coast of North Carolina, where the birds are 

 plentiful. There I only noticed them late in the summer and during 

 the autumn, though I presume they pass by in the spring; none breed 

 there, to my knowledge. In September they become plentiful, and so 

 continue until the latter part of November, some doubtless remaining 

 later. In examining large numbers of specimens I found a great differ- 

 ence in size, and particularly in the bill. Some individuals are fully a 

 third heavier than others. The bill varies over an inch in length, and 

 especially in the length of the under mandible. Sometimes the differ- 

 ence between the two mandibles is hardly a third of an inch, at others 

 over an inch. The oblique strice on the under one are sometimes obso- 

 lete. In high condition the bill is bright red (vermilion) and black; 

 otherwise orange and black, or even mostly dusky, only yellowish at 

 base. The young in the fall are curiously variegated with dusky and 

 whitish above, few specimens being exactly alike. The note of this 

 species is instantly distinguished from that of any of our other species 

 of this family by its deep guttural intonation, more like the croaking of 

 some Herons than the cries of tlie Gulls and Terns. The bird also 

 differs from its allies in going in true flocks, as distinguished from the 

 gatherings, however large, in community of interest, that occur with 

 the Gulls and Terns. The birds move synchronously, which is not the 

 case with any of the others. They feed chietly by night, or at any rate 

 in the dusk of the evening, at which time, in passing over the harbor, 

 one may hear their hoarse notes on every hantl, and see the birds gliding 

 swiftly along just over the water, either singly or in small Hocks. 

 During the daytime, when the Gulls and Terns are busy fishing, the 

 Skimmers are generally seen reposing on the sand-bars. They never 

 drop on their prey on the wing, like their allies. Their mode of feeding- 

 is not exactly made out, but it is believed they skim over the surface 

 with the body inclined downward, the bill open, and the under maiulible 

 in the water, so they really take their prey in a manner analogous to 

 the feeding of whales. 



