431 
of the United States . 
moderate, depressed, narrow before, rounded behind ; eyes 
small : neck short, thick : body massive. Tibije much drawn 
in ; tarsus one third shorter than the middle toe, moderately 
robust, carinated on both sides ; toes rather stout, middle 
slightly longest ; inner shortest : webs not very broad, entire : 
nails moderately curved, acute, middle largest, dilated slight- 
ly into an edge. Wings short, acute; quills acute; first 
primary longest ; secondaries much abbreviated. Tail or 
twelve or sixteen acute feathers. 
Female perfectly similar to the male. Young well distin- 
guished from the adult by their small and nearly smooth bill. 
Moult twice in the year, changing the colors of their head o 
Feathers short. 
Live at sea among the ice, not far from shore : those that 
can, fly rapidly, though short distances : throwing themselves 
into the sea instantaneously without alighting on the surface. 
Walk with extreme awkwardness, and bearing much upon the 
tarsus, so that the species that cannot fly, must either swim of 
crawl. Feed on fishes and smaller marine animals, w T hich they 
catch by diving : swim and dive admirably well. Breed soci- 
ally in caves and clefts of rocks, where they also retire at 
night : lay but a single egg, disproportionately large. Young 
abundantly fed by the parents, even for some time after leav- 
ing the nest. 
Arctic : formed of two w 7 idely different species, one of 
which does not leave the polar circle. 
381. Alca torda, L. Black, beneath white ; wings capable 
of flight, when folded reaching to the rump ; tail moderate, 
cuneiform, of twelve feathers. 
Adult, bill with three or four lateral grooves : summer plu- 
mage, whole head black : a white line from the bill to the eye. 
Young, bill smooth. 
Razor-bill of Wilson's list . Buff. pi. enl. 1003. summer dr. 
1004. winter plumage. Alca pica and torda , L . A. balthica ? 
uni-sulcata, et minor , auct. 
