BLACK-THROATED DIVER. 297 



Colymbds arcticus, Bonap. Syn., p. 420. 



Coly3ibus arcticus, Black-throated Diver, Swains, and Rich. F. Bor. Amer., vol. ii. 



p. 475. 

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

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



Male, 29, 391 



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. 



Adult Male. . 



Bill as long as the head, straight, stout, higher than broad at the base, 

 much compressed toward the end, and tapering to a point. Upper mandible 

 with the dorsal line descending and considerably convex toward the end, 

 the ridge convex, narrowed toward the point, the sides convex beyond the 

 nostrils, the edges involute for half their length in the middle, direct at the 

 base and toward the end, the tip narrow and sharpish. Nasal groove rather 

 long and narrowed; nostrils sub-basal, linear, direct, pervious. Lower 

 mandible with the angle extremely narrow, and very long, the dorsal line 

 ascending and very slightly convex, the ridge convex and narrow, the edges 

 sharp and involute, the tip attenuated. 



Head of moderate size, oblong, narrowed before. Neck rather long and 

 thick. Eyes of moderate size. Body elongated, much depressed, of an 

 elliptical form viewed from above. Wings small. Feet short, rather large, 

 placed very far back; tibia almost entirely concealed; tarsus short, exceed- 

 ingly compressed, sharp-edged before and behind, covered all over with 

 reticulated angular scales, hind toe extremely small, externally marginate, 

 connected with the second for half its length by a membrane, which extends, 

 narrowing, to the end; the anterior toes connected by articulated membranes, 

 the fourth or outer longest, the third a little shorter, the second considerably 

 shorter than the third; all covered above with numerous narrow scutella; 

 the second toe with a free two-lobed membrane, the claws very small, 

 depressed, blunt. 



Plumage short and dense, of the head and neck very short, soft and 

 blended; of the lower parts short, blended, stiffish, considerably glossed; of 

 the upper compact, glossy; the feathers on the lower part of the sides of the 

 neck much incurved, oblong, with the terminal barbs stiff; those of the fore 

 part of the back and the scapulars straight, oblong, abrupt. Wings propor- 

 tionally very small and narrow, curved; primaries strong, tapering, the first 

 longest, the second slightly shorter, the rest rapidly graduated; secondaries 

 very short, broad, and rounded. Tail extremely short, rounded, of eighteen 

 feathers. 



Vol. VII. 42 



