66
FAMILY XLII.— LARINJE. GULLS.
Bill of moderate length, straight, compressed, acute; upper mandible with the dorsal line generally straight until toward the end, when it is decurved, the ridge convex, the nasal groove rather long, the edges sharp, direct, over- lapping, the tip rather acute and declinate; lower mandible with the angle long and very narrow, the dorsal line ascending and nearly straight, with an angular prominence at its commencement. Nostrils sub-medial or basal, oblong. Head of moderate size, ovate; neck of moderate length; body rather stout. Legs short or of moderate length; tibia bare at its lower part; tarsus anteriorly scutellate; toes four, the first very small, free, the third longest; anterior toes connected by webs. Claws small, arched, compressed, rather acute. Plumage full, soft, blended, somewhat compact on the back and wings, the latter long and pointed; tail of twelve feathers, even, rounded, or emarginate. Tongue long, slender, pointed; oesophagus very wide; sto- mach rather small, moderately muscular, with a dense, longitudinally rugous epithelium; intestine of moderate length and width; coeca small; cloaca globular. Trachea simple, with a single pair of inferior laryngeal muscles. Nest on the ground, rudely constructed. Eggs few, not exceeding four, spotted. Young covered with down.
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
