180 
BLACK-THROATED DIVER. 
Colymbus arcticus, Bonap. Syn., p. 420. 
Colymeus arcticus, Black-throated Diver , Swains, and Rich. F. Bor. Araer., vol. 
ii. p. 475. 
Black-throated Diver, Nutt. Mann., vol.ii. p. 517. 
Black-throated Diver, Colymbus arcticus , Aud. Orn. Biog., vol. iv. p. 345, 
Male, 29, 39£. 
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 oyer 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. 
