Genus II— ALCA, Linn. AUK. 
Bill as long as the head, feathered as far as the nostrils, beyond -which it 
is very high, exceedingly compressed, and. obliquely furrowed on the sides ; 
upper mandible with the dorsal line decurved, the ridge extremely narrow, 
the sides nearly flat, the nasal groove very large, and feathered, with its 
lower margin very narrow, and convex, the edges sharp and inflected, the 
tip decurved, very narrow, but obtuse ; lower mandible with the angle very 
narrow, and having a horny triangular appendage, the sides at first extreme- 
ly narrow, towards the end erect and flat, the edges inflected, the dorsal out- 
line concave, the tip decurved. Nostrils medial marginal, linear, short, con- 
cealed by the feathers. Head large, ovate ; neck short and thick ; body full, 
rather depressed. Feet placed far behind, short, stout ; tibia bare for a short 
space ; tarsus very short, compressed, anteriorly scutellate; hind toe wanting; 
anterior toes of moderate length, rather slender, scutellate, webbed, the outer 
slightly longer than the middle. Claws rather small, arched, compressed, 
obtuse. Plumage close, blended, very soft. Wings very short, narrow, 
acute, first quill longest. Tail short, tapering, of twelve or fourteen feathers. 
