Family XLII. LARINAE. GULLS.
GENUS I. RHYNCHOPS, Linn. SKIMMER
Bill longer than the head, nearly straight, tetragonal at the base, suddenly extremely compressed and continuing so to the end; upper mandible much shorter than the lower, its ridge sharp, the sides erect but a little convex, the edges approximated so as to leave merely a very narrow groove between them, the tip a little rounded, when viewed laterally; nasal groove rather short, near the margin; lower mandible with the angle extremely short, the dorsal line straight or slightly decurved, the sides erect, obliquely grooved, the edges united into a very thin blade, which fits into the narrow groove of the upper mandible, the tip rounded or abrupt, when viewed laterally. Nostrils linear-oblong. Head rather large, oblong, considerably elevated in front; neck rather short, thick; body short, ovate. Feet short, moderately stout; tibia bare below, with narrow transverse scutella before and behind; tarsus short, anteriorly covered with broad scutella; toes very small, the first extremely short and free, unless at the base; middle toe slightly longer than outer; anterior toes united by deeply emarginate webs. Claws long, compressed, slightly arched, rather obtuse. Plumage moderately full, soft, and blended; wings extremely long, and very narrow; primary quills excessively long, the first longest; secondaries short. Tail of moderate length, deeply forked, of twelve feathers. Tongue short, triangular, tapering; oesophagus wide; stomach rather small, oblong, muscular, the cuticular lining dense, with nine broad longitudinal rugae; intestine rather long, narrow; coeca very small; cloaca large, globular; the digestive organs are precisely similar to those of the Terns and smaller Gulls.