OF ORNITHOLOGY 131 



Sub-family b LARIN-ffi True Gulls 



The True Gulls are too well known to need any extended 

 introduction. Though some of the species are giants and oth- 

 ers dwarfs, they all possess a similarity of appearance and of 

 habit which at once characterizes them and binds them to- 

 gether. They have little of the agile flash-like flight of the 

 Skua's, and still less of the methodical scissor-like flight of 

 the Terns. They are, rather, bold, powerful, slow-moving 

 brigands, whose wild screaches send terror into the hearts of 

 all smaller species, whom they seem to laugh at as if they con- 

 sidered them much inferior beings. The sexes are alike as to 

 plumage in the Gulls as well as in the Terns. The young are 

 of different degrees of brownish or greyish-brown, and dis- 

 tinctly noticeable even among the flying birds. They are two 

 to three years in maturing, the plumage from very dark brown 

 becoming lighter and lighter at each succeeding moult. A 

 full and thorough study of the Gulls has never been made. 

 We shall not attempt to characterize it further. 



Genera, Larus, The Gulls Proper (14 or 15 species). 



Chroicocephalus, The Laughing and Rosy Gulls (3 species). 



Pagophila, The Ivory Gull. 



Rissa, The Kittiwakes (3 species). 



Rhodostethia, Ross's Gull. 



Xema, Sabine's Gull. 



Creagrus, The Swallow-tailed Gull. 



Some writers do not recognize Chroic.oceplialus as differing from Larus — 



unless, perhaps, as a sub-genus ; and, though the distinction is more nearly 



generic, yet really Rhodostethia is certainly a sub-genus of Rissa. 



In the same way, if not really a distinct genus, Creagrus is a sub-genus of 



Xema. 



The synonymy of this sub-family had better not be attempted by the young 



student, as he will find a strange tangle of Larus, Laroides, Leucus, At- 



ricilla, etc., and other vexing suggestions. 



Sub-family c STERNINiE Terns 



The difference between the True Gulls and the Terns is not 

 technically so great as would at first seem. The general ap- 

 pearance, however, is much more evident. The long, pointed 

 wing, the strongly marked bend of the wing, and the length- 



