Birds of America
By John James Audubon, F. R. SS. L. & E.
GENUS III.--LARUS, Linn. GULL.
Bill shorter than the head, nearly straight, moderately stout, compressed;
upper mandible with its dorsal outline straight to the middle, then decurved,
the ridge convex, the sides rapidly sloping, the edges sharp and direct, the tip
rather obtuse; nasal groove rather long and narrow; nostrils sub-medial,
longitudinal, linear-oblong, broader anteriorly; lower mandible with the angle
long and pointed, the outline of its crura decurved anteriorly, that of the
ridge slightly concave and ascending, the sides erect, the edge-line decurved
toward the tip, which is narrow but obtuse. Head of moderate size, broadly
ovate; neck of ordinary length; body compact. Feet rather long or of moderate
length, rather stout; tibia bare at the lower part; tarsus moderately
compressed, with numerous curved anterior scutella, and smaller behind; toes
slender, of moderate length, scutellate; first very small, third a little longer
than fourth. Claws small, slightly arched, compressed, rather blunt. Plumage
close, soft, blended, on the back and wings rather compact. Wings very long,
pointed; first and second quills longest; secondaries broad, the inner more
elongated. Tail of moderate length, generally even, rarely rounded or
emarginate, of twelve feathers. In those which have the head white in summer,
it is streaked with dusky in winter; and those which are hooded in summer, have
the head white and slightly streaked in winter.