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"Sterna (T.) caspia. Caspian Tern. Imperial Tern. Bill dark vermilion red, growing and somewhat "diaphanous" toward the tip. Pileum and occipital crest glossy greenish-black, extending to below the lower level of the eyes, and occupying the termination of the feathers on the side of the mandible to the exclusion of the white; lower eyelid white, forming a noticeable spot on the greenish; a white streak along sides of upper mandible, not extending to the end of the feathers. mantle pearl-blue, the line of demarcation between it and the white rather indefinite, both on nape and rump; most of the tail-feathers, and especially the central ones, retaining a more or less pearly tint. Shafts of the primaries yellowish-white; primaries grayish-black, but, when new, so heavily silvered over as to appear of a light hoary gray, especially on their superior aspects. On the inner web of all there is a central light field; this is very narrow, even on the first primary, although it runs considerable distance, and on the others it rapidly grows less; and it has no trenchant line of division of the primaries from the darker portions of the feather. whole inner web of secondaries pure white, outer pearl-blue. Legs and feet black." Elliot Coues, 1884

Caspian Tern

"Sterna (T.) caspia. Caspian Tern. Imperial Tern. Bill dark vermilion red, growing and somewhat "diaphanous"…

"Sterna (T.) maxima. Cayenne Tern. Royal Tern. Adult in summer: Pileum glossy greenish-black, not extending below eyes, so narrow on side of upper mandible that a broad white streak extends to extreme tip of the feathers. Mantle exceedingly light pearl-blue, fading imperceptibly into white on the rump and towards the extremities of the tertials. Tail white, with a faint tinge of pearly, especially on the central feathers and inner webs of the other. Secondaries pure white for their whole length except a small space on the outer web near the tip, which is grayish-blue, deeper than the mantle. Outer web of first primary grayish-black; in the inner web of the same has a space of black extending the whole length of the feather, very narrow at the base, widening as it runs toward the tip. within 1 & 1/2 inches of which it occupies the whole web; the rest of the web white. separated from the black by a straight distinct line of division. The second, third, fourth, and fifth primaries have the same general characteristics, but the white space grows narrow and shorter, and round up further in the centre than along the edge of the web, so that for a little way from its end it has a border of blackish along its outer margin; other primaries wholly pearl-blue, their inner webs margined with white. Bill coral and orange-red, with a slightly lighter tip; feet blackish, their soles dull yellowish." Elliot Coues, 1884

Royal Tern

"Sterna (T.) maxima. Cayenne Tern. Royal Tern. Adult in summer: Pileum glossy greenish-black, not extending…

"Sterna (T.) cantiaca. Sandwich Tern. Ducal Tern. Bill black, the tip 1/2 to 3/4 an inch bright yellow, sharply defined against the black; "inside of mouth deep blue." Feet dull black. Pileum and occipital crest glossy black, with a tinge of green; the color extending just below the eyes, but leaving a space along the side of the mandible white to the extremity of the feathers. Mandible exceedingly light pearly-blue, fading on the rump and upper tail-coverts into pure white; but the rectrices themselves have a slight shade of pearly-bluish. Primaries colored as in maxima. On the inner web of the first the black space is broad and deep in color; when about 1& 1/2 inches from the apex of the quill it quite suddenly grows wider, so as to exclude the white portion from the tip altogether. The second, third, and fourth primaries have the same general pattern, but he white runs up further on the central portion than on the edge of the web, so that toward its end it receives a narrow edging of blackish. The other primaries have no blackish, but are simply pearl-blue, with broad white margins along the whole length of heir inner webs. The outer primaries are all heavily silvered when the quills are new.

Sandwich Tern

"Sterna (T.) cantiaca. Sandwich Tern. Ducal Tern. Bill black, the tip 1/2 to 3/4 an inch bright yellow,…