This species is less than the common tern; weight about two ounces and
three-quarters; length ten inches; bill black; irides dusky; forehead,
sides of the head, beneath the eyes, throat, and fore part of the neck
white; the rest of the head, back of the neck, and under part of the
body, black; back, wings, and tail, deep ash-colour; vent and under
tail-coverts white; the tail is less forked than in either of the other
species; the outer feathers edged with white; legs dull red, the webs
much indented or semipalmated. In some the forehead and fore part of the
neck are mottled with black; and as most authors have omitted, or at
least have not made mention of any white on the forehead, such is
probably another variety. The female has no white about the
head.—_Montagu._