of the United States. 431 



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 # 

 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, which 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 widely 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. 



