Order LONGIPENNES. 



THE LONG-WINGED SWIMMEES. 



Char. Nostrils lateral and perforate, never tubular ; covering of the bill simple, 

 or broken only by a sort of imperfect cere (in Stercorariidce). Tip of the maxilla 

 never strongly hooked, often straight. Hallux generally well developed, but small 

 and elevated, sometimes rudimentary. Basipterygoid bones absent. Eggs several, 

 colored. Habit highly volucral. 



The following groups, which it seems to us should rank as families, have usually 

 had only the value of sub-families assigned them. They are so very strongly marked, 

 however, that no intermediate forms are known. 



A« Covering of the bill simple. 



1. Rhynchopidae. Bill iiuich longer than the head, excessively compressed, except at the 



extreme base, the mandible much longer than the maxilla, both broad and nearly truncate. 

 Tail much shorter than the wing, forked. Legs and feet extremely small. 



2. Laridae. Bill rarely longer than the head (usually shorter), moderately compressed, or 



sometimes nearly cylindrical, pointed, the maxilla always longer than the mandible. Tail 

 variable in length and shape. Legs and feet of proportionate size. 

 B. Covering of the bill comjMund. 



3. Stercorariidae. Bill shorter than the head, the terminal half of the culmen strongly 



curved, the basal half consisting of a horny cere, beneath the overhanging edge of which 

 the nostrils are situated. Feet rather strong, the claws well developed, rather strongly 

 curved. Tail nearly even, but the intermedia) more or less prolonged beyond the other 

 rectrices, their tips rounded or pointed, according to the species. 



Family RHYNCHOriD.E. — The Skimmers. 



Char. Bill compressed to knife-like thinness, except at the extreme base, the 

 mandible much longer than the maxilla, the latter freely movable. Nostrils basal, 

 inferior. Wings extremely lengthened. Tail about one third the wing, slightly 

 forked. Legs and feet extremely small. 



The peculiarities of form expressed in the characters given above render this very 

 remarkable type worthy, according to our views, of family rank, as distinguished from 

 the Gulls and Terns, the most widely different forms of which are perfectly imited 

 by the interposition of a graduated series of intermediate forms, Avhile between 

 Rhynchops and any of the Larichv there exists a very wide gap. Tlie family is 

 composed of the single genus EJujiichops. 



