“Adult male in breeding plumage.—Forehead nearly white at base of bill, passing on the crown into lavender-gray, which deepens on neck into lead-color; lores and orbital region black, with a faint whitish superciliary streak; upper parts chiefly dark brown; primaries, tail-feathers, and their shafts nearly black; under parts dark brown on abdomen and breast, passing into deep lead-color on the throat. Bill blackish; tarsi and toes reddish brown, fully webbed, webs ochraceous. Length, about 406; culmen, 53; wing, 260 to 280; tail, 152 to 178, the fourth feather from the outside the longest; tarsus, 25; middle toe with claw, 39.
“Adult female.—Very similar but, as a rule, somewhat browner on the shoulders and with less lead-color on the throat, slightly smaller, and with a weaker bill.
“Immature.—Similar, but with even less lead-color, and a dark line along the upper wing-coverts.
“Young.—Browner generally and paler; forehead and crown grayish brown; below the forehead a narrow white superciliary line conspicuous by contrast against the blackish lores.
“Fledgling (Ascension I.).—Umber-brown above and below; the whitish streak above the lores very marked, and continuous round base of bill; a slight grayish tint on forehead.
“Downy nestling.—One about five days old (British Honduras: May 12, 1862) has the forehead and crown dull white, lores blackish, upper surface mouse-brown, nape and throat darkest, lower parts paler. Another, only just hatched, is nearly uniform, sooty brown.” (Saunders.)
Subfamily LARINÆ.
Of larger size than the terns; body and bill heavier; tail square or nearly so.
Genus LARUS Linnæus, 1758.
Characters same as those given for the Subfamily.