Bill generally shorter than the head, moderately stout, compressed;
upper mandible with the ridge formed of two generally united plates,
at the anterior part of which, usually about half the length of the
bill, are the nostrils; the sides separated by a groove, the tip a
decurved, compressed, pointed unguis; lower mandible with the angle
very long and narrow, the tip more or less decurved. Head of moderate
size, ovate; neck of moderate length; body compact. Feet of ordinary
length, rather slender; tibia bare below for a short space; tarsus
little compressed, anteriorly scutellate; toes four, the first
extremely small and elevated, with a conical deflected claw; anterior
toes webbed; the third and fourth nearly equal. Claws arched,
compressed, acute. Plumage full, soft, rather compact above. Wings
long, rather broad, pointed, the first quill generally longest. Tail
short, of from twelve to sixteen feathers. Œsophagus very wide,
often enormously dilated, especially at its lower part, stomach small,
moderately muscular; intestine of moderate length; cœca rather
long; cloaca oblong or globular. Trachea simple, with a single pair of
inferior laryngeal muscles.
GENUS I. LESTRIS, Illiger. JAGER.
Bill shorter than the head, strong, slightly compressed, straight,
with the tip curved; upper mandible with the dorsal line nearly
straight, toward the tip decurved, the ridge broad and convex, formed
by two plates, which overlap the nostrils, the sides narrow and
convex, the edges sharp and inflected, the tip or unguis decurved,
compressed, acute; nasal groove long, narrow; the nostrils in its fore
part medial, lateral, longitudinal, broad before, extremely narrow
behind, open and pervious; lower mandible with the angle long and
narrow, a slight prominence at its extremity, beyond which the dorsal
line is slightly concave, the sides erect, and slightly convex, the
edges sharp and inflected, the tip obliquely truncate. Head rather
large; neck of moderate length; body rather full. Feet of moderate
length, rather stout; tibia bare at its lower part, and rough all
round, with small convex scales; tarsus compressed behind and
scabrous, anteriorly scutellate; hind toe extremely small and
elevated; fore toes of moderate size, connected by convex webs, the
third toe longest, the fourth little shorter. Claws strong, much
curved, very acute, compressed. Plumage full, soft, blended, on the
back rather compact. Wings very long, rather broad, pointed, the first
quill longest. Tail of moderate length, or elongated, of twelve
feathers, of which the middle are longest. Tongue broadly channelled
above, contracted and induplicate toward the end, with the point slit;
œsophagus very wide; stomach small, moderately muscular, with the
epithelium thin, dense, and longitudinally rugous; intestine rather
short and wide; cœca rather long; cloaca oblong.