Haliaëtus pelagicus. (Pallas.) Aquila pelagica. Pallas, Zoographia Rosso-Asiatica, I. p. 343, (St. Petersburg, 1811, Quarto.) “Aquila marina. Steller, MSS.” Pallas _ut supra_. Falco Imperator. Kittlitz, Kupfertafeln zur naturg. der Vogel pt. I. p. 3, pl. 2, (Frankfurt, 1832.) Falco leucopterus. Temminck. Pl. col. I. pl. 489. Haliaëtus pelagicus. (Pallas.) Temm. & Schl. Fauna Japonica, Aves p. 10, pl. 4. Haliaëtus imperator. (Kittlitz.) Bruch in Isis XXV. p. 1102, (1832.) Form. Very large and powerful, tail rather short, wedge shaped, the middle feathers being nearly four inches longer than the outer, which are shortest, all of the fourteen feathers somewhat pointed, but the central four lanceolate. Bill strong, much compressed, very wide laterally or in altitude; upper mandible with a slight festoon; gape rather wide, extending so far back as to be immediately under the eye; cere large, in which at the distance of nearly an inch from the frontal feathers, the nostrils are obliquely inserted, large loral space bare, or with a few scattered bristles. Wings rather short, third and fourth quills longest, but with the fifth little shorter; secondaries abruptly acuminated, and some of them with their shafts produced into filaments or thread-like appendages, exserted from the tips of the feathers; secondaries and greater coverts very broad and strong. Legs and feet rather short, but strong; tarsus feathered below the joint for half its length, bare lower portion, with about five large frontal scales immediately succeeding the feathers; then to the toes in common with its entire posterior part, covered with numerous scales, which are rounded or hexagonal: the latter shape most readily observed behind; toes, with broad frontal scales; claws large. Feathers of the head and neck, narrow and pointed, or acuminated; those on the breast and back, somewhat lanceolate, but broad, and sometimes abruptly pointed. Tail coverts, both above and below, ample—extending to half the length of the tail. Dimensions of a skin from Behrings Straits. Total length from tip of bill to end of tail, about 3 feet 8 inches; wing, 2 feet 2 inches; tail, 1 foot 4 inches; bill, from tip of upper mandible to angle of the mouth, 3¾ inches; width of bill, laterally, at point of insertion of the nostrils, full 1¾ inches. Colours. Female, nearly adult? Tail, white, the two external feathers having their outer webs, brownish black, mottled with white, and other feathers slightly spotted with the same brownish black. Entire other parts, above and below, very dark brownish black; lighter on the head and neck, and on which parts every feather is lighter in the middle.