866 U. &. P. R. R. EXP. AND SURVEYS—ZOOLOGY—GENERAL REPORT. 
RHYNCHOPS, Linnaeus. 
Rynchops, Linn. Syst. Nat. 1756. 
Cu.—Bill very broad at the base, from whence it becomes suddenly compressed for its entire length; upper mandible 
considerably shorter than the lower and curving gradually to the tip, which is pointed, it is narrowly grooved underneath ; the 
lower mandible is straight and truncated, much more compressed than the upper, and having the cutting edge very sharp to 
admit of its being received in the groove of the upper mandible; nostrils basal, oblong and lateral; wings much elongated, first 
quill longest; tail forked; tarsi longer than the middle toe; toes rather short, united by an indented web; hind toe rather 
elevated ; claws much curved and acute. 
But one species of this very peculiar genus is found on our southern coast. 
They are stated by Audubon to be nocturnal in their habits, resting during the day upon 
sand bars, 
RHYNCHOPS NIGRA, Linnaeus. 
The Black Skimmer. 
Rynchops nigra, Linn. Syst. Nat. I, 1766, 228.—Wixs. Am. Orn. VII, 1813, 85; pl. 1x.—Bownar. Syn. 1828, No. 
283.—Norr. Man. H, 1834, 264.—Aup. Orn, Biog. IV, 1838, 203.—Is. Birds Am. VII, 1843, 
67; pl. cccexxxiii. 
Sp. Cu.—Adult. Front as far as the eye, throat and under plumage, white; crown, hind neck, wings and back, deep 
brownish black ; primaries black, with the four inner ones white on their inner webs and tips; secondaries broadly tipped with 
white; central tail feathers dark brown, the others mostly white, some of them light brown on their inner webs; bill carmine 
for about half its length, then black to the end; iris hazel ; tarsi and feet red. 
Length of male, about 19 inches ; wing, 143 ; tail, 5; lower mandible, 4}, upper, 3§ ; tarsi, 1}. 
Female smaller. 
Hab.—F rom Texas to New Jersey. 
Specimens in my cabinet and that of Smithsonian Institution. 
