Birds of America
By John James Audubon, F. R. SS. L. & E.
VOLUME VII.
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.