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, overlapping, 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 submedial 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;
œsophagus very wide; stomach rather small, moderately muscular,
with a dense, longitudinally rugous epithelium; intestine of moderate
length and width; cœca 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
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;
œsophagus wide; stomach rather small, oblong, muscular, the
cuticular lining dense, with nine broad longitudinal rugæ; intestine
rather long, narrow; cœca very small; cloaca large, globular, the
digestive organs are precisely similar to those of the Terns and
smaller Gulls.