Part 166

GENUS I. COLYMBUS, Linn. DIVER.

Bill as long as the head, straight, rather stout, much compressed, tapering, pointed; upper mandible with the dorsal line descending, and slightly convex towards the end, the ridge convex, narrowed towards the point, the sides nearly erect, convex, the edges sharp and considerably inflected; the tip narrow; nasal groove rather long, feathered at the base. Nostrils basal, linear, direct, pervious; lower mandible with the angle extremely narrow and extending beyond the middle, the dorsal line straight and sloping towards the point, the ridge convex and narrow, the edges sharp and involute, the tip attenuated. Head of moderate size or rather large, oblong, narrowed before; neck rather long and thick; body elongated, much depressed. Feet short, rather large, placed very far back; tibia almost entirely concealed; tarsus short, exceedingly compressed, sharp-edged before and behind, covered all over with reticulated scales; toes four, hind toe extremely small, connected with the second by a very small membrane; anterior toes united by entire membranes, the outer longest, the third a little shorter, all scutellate. Claws very small, depressed, blunt. Plumage short and dense, the feathers in general oblong. Wings very small and narrow, curved, first quill longest, secondaries broad and rounded. Tail extremely short, rounded of more than twelve feathers. Tongue long, trigonal, tapering; œsophagus very wide; proventriculus extremely dilated; stomach rather large, roundish, a little compressed, moderately muscular, with a rather thick, dense, longitudinally rugous epithelium; intestine rather long and wide; cœca rather long and wide; cloaca globular.

484. 1. Colymbus glacialis, Linn. Great Northern Diver.--Loon.

Plate CCCVI. Male, and Young in winter.

Adult in summer with the bill black, the feet livid greyish-blue, their inner sides tinged with flesh-colour; head and neck dark greenish-blue with purple gloss; on the throat a small transverse patch of white longitudinally streaked with dusky; above the middle of the neck two large patches of white similarly streaked, separated in front to the distance of an inch, but almost continuous behind; lower parts glossy white, excepting the feathers on the sides under the wings, which are black, each with two, three, or four elliptical white spots, a faint dusky band across the vent, the lower tail-coverts, which are brownish-black tipped with white, and the axillar-feathers and large wing-coverts, which have a dusky streak along the middle; sides of the neck at its lower part longitudinally streaked with black and white; upper parts glossy black, variegated with spots of white in regular transverse slightly curved lines, having the convexity backwards, the spots small and roundish towards the neck and sides, larger and somewhat four-sided along the middle of the back, largest and rectangular on the scapulars, very small and roundish on the hind part of the back and tail-coverts; upper part of wing similar, with smallish spots; alula and quills brownish-black, a few of the inner secondaries only having two white spots at the end of the tail brownish-black, of twenty feathers. Young in winter with the bill pale yellowish-green, the ridge and tip of the upper mandible dusky; upper parts dark greyish-brown, each feather margined with lighter, lower parts white, sides of the neck below streaked with dusky, sides of body dusky, without spots.

Adult, 32-7/8, 57-1/2. Young Male, in winter, 31-1/4, 54-1/2.

During winter dispersed over the United States, in Texas, as well as along the coasts of the Atlantic, and the north-west. Breeds from Massachusetts northward to very high latitudes. Common.

Great Northern Diver or Loon, Wils. Amer. Orn. v. ix.

Colymbus glacialis, Bonap. Syn. p. 420.

Colymbus glacialis, Great Northern Diver, Swains. & Rich. F. Bor. Amer. v. ii. p. 474.

Loon or Great Northern Diver, Nutt. Man. v. ii. p. 513.

Great Northern Diver or Loon, Colymbus glacialis, Aud. Orn. Biog. v. iv. p. 43.

485. 2. Colymbus arcticus, Linn. Black-throated Diver.

Plate CCII. Male, Female, and Young in winter.

Adult in summer with the bill black, the feet greyish-blue, the anterior edge of the tarsus, upper surface of toes, and part of the webs, pale livid flesh-colour; fore part and sides of head, throat, and sides of neck light bluish-grey, fore part and sides of head darker; upper parts glossy bluish-black, tinged with green anteriorly, and shaded with brown posteriorly; on the fore part of the back two longitudinal bands of transverse white bars, the feathers being tipped with that colour; the scapulars, excepting the outer, marked in the same manner with transverse rows of rather large square spots; most of the wing-coverts with two roundish spots of white near the end; quills blackish-brown, tinged with grey externally, paler on the inner webs; tail blackish-brown, of eighteen feathers; fore neck to the length of six and a half inches purplish-black, ending angularly below, and with a transverse interrupted band of linear-white spots near the upper part, beyond which the sides of the neck blackish-brown, with several longitudinal white streaks, formed by the edges of the feather; on the lower part of the neck a broad space occupied by their longitudinal dusky and white streaks; lower parts pure white, except a dusky longitudinal band on the sides under the wing. Young in winter with the bill bluish-grey, on the ridge dusky; upper part of head and hind neck dark greyish-brown, sides of head greyish-white, minutely streaked with brown, sides of neck also streaked, its fore part faintly mottled; lower parts white, the sides and lower tail-coverts greyish-brown; upper parts blackish-brown, the feathers broadly edged with pale grey, quills and tail brownish-black.

Male, 29, 39-1/2.

The young range throughout the interior and along the coast as far as Texas, in autumn and winter. Adult in full plumage very rare. Breeds in high latitudes. Columbia River.

Colymbus arcticus, Bonap. Syn. p. 420.

Colymbus arcticus, Black-throated Diver, Swains. & Rich. F. Bor. Amer. v. ii. p. 475.

Black-throated Diver, Nutt. Man. v. ii. p. 517.

Black-throated Diver, Colymbus arcticus, Aud. Orn. Biog. v. iv. p. 345.

486. 3. Colymbus septentrionalis, Linn. Red-throated Diver.

Plate CCII. Male in summer, Male in winter, Female, and Young.

Adult, in summer, with the bill bluish-black, the feet brownish-black, anterior part of tarsus, upper surface of toes, and part of webs, livid flesh-colour; fore part and sides of head, throat, and sides of neck, bluish-grey; fore part of neck rich brownish-red; hind part of head and hind neck longitudinally streaked with greenish-black and pure white, each feather black in the middle, with the sides white, the colours disposed in lines; upper parts in general brownish-black, tinged with green, more or less mottled with white, according to age, excepting the primary quills and the tail-feathers, of which there are twenty; lower parts pure white, excepting the feathers on the sides under the wings, some of those about the vent, and the lower tail-coverts, which are greyish-brown, with white margins and tips. Young, in winter, with the fore part of the neck white, or slightly mottled with red; all the feathers of the upper parts with two white spots near the end; tail-feathers edged and tipped with white. Young at first covered with dense elastic down, of a greyish-black colour, tinged with Brown.

Male, 19, 25. Female, 18, 24.

Not uncommon during winter, autumn, and early spring, from Maryland eastward. Breeds in Newfoundland, Labrador, and as far north as the Arctic Seas.

Colymbus septentrionalis, Bonap. Syn. p. 421.

Red-throated Diver, Colymbus septentrionalis, Swains. & Rich. F. Bor. Amer. v. ii. p. 476.