of (he United States. 405 



base, ridge deeply grooved each side, edges dilated, sharp, 

 entire : nostrils in the furrows, basal, linear, obsolete : 

 tongue very short, lanceolate : gape very wide : orbits and 

 lores naked : throat dilatable, pouch large. Head moderate ; 

 eyes large : neck moderate : body compressed, elongated. 

 Feet very short, drawn up into the belly ; tibia? wholly 

 feathered ; tarsus one third shorter than the outer toe, much 

 compressed, carinated before and behind, half feathered ; toes 

 long, semipalmated, the connecting membrane being deeply 

 indented ; second much the longest ; outer longer, but 

 subequal to the inner, edged exteriorly by a small mem- 

 brane; hind toe half as long as the middle; nails large, 

 curved, acute : middle serrated on the inner edge, twice as 

 large as the others. Wings extremely long, very narrow ; 

 first primary longest, the others decreasing successively very 

 much. Tail deeply forked, of twelve flaccid feathers. 



Female similar to the male. Young differing from the 

 adult, and changing repeatedly. Moult twice a year, chang- 

 ing somewhat in color. Plumage not water proof. Colors 

 black. 



Tyrants of the ocean. Associate in small flocks. Keep 

 constantly on the wing, flying swiftly against the strongest 

 gales, and rising above the clouds. Easily distinguished at 

 a distance. Traversing rapidly vast spaces, and appearing 

 farthest at sea, though hardly able to rest on the water 

 on account of the nature of their plumage. Never dive 

 nor swim. Resting only on trees, or on high rocks : unable 

 to rise, and easily caught when on the ground. Following 

 large voracious fishes in pursuit of small ones, in order to 

 catch the latter as they leap out of water, often seizing the 

 pursuer himself. Prey also on the Pelicans, but especially 

 on the Gulls and Boobies, which they compel, always keep- 

 ing above them, to drop the fruits of their industry, or even 

 to disgorge what they had swallowed, seizing it before it 

 reaches the water. Flight very rapid. Sight very keen. 



Vol. II. 51 



