BIRDS OF NEW YORK II9 



that the tail feathers are about three inches shorter than the dimensions 

 given by Swainson and Richardson. There seems no doubt also that the 

 specimens from Gowanus bay [Birds of L. I. p. 365] may be the young of 

 the Parasitic jaeger. The specimen to which he refers as L e s t r i s 

 r i c h a r d s o n i [p. 367] is a Parasitic jaeger in the dark phase; thus it 

 appears that none cf Giraud's specimens can be referred with certainty to 

 the species longicaudus, although he himself refers two to that species, 

 DeKay's Lestris richardsoni is undoubtedly a Parasitic jaeger. 

 His L. buffoni is probably the same species, although it may be the 

 intermediate phase of longicaudus. 



Family LARIDA-E 



Gulls and Terns 



Gulls and terns are distinguished by the structure of their bills, which 

 are more or less epignathous and somewhat compressed, with a protuberant 

 gonys, but lacking the homy saddle of the jaegers. The nostrils are linear 

 or oblong, placed toward the middle or in the basal half of the bill, and are 

 open transversely. Among the gulls, especially the larger s]:)ecies, the 

 bill is stout, and hooked near the end, and the short syniph^'sis of the 

 branches of the lower mandible makes a prominent gonys, or angle of the 

 jaw. There is a continuous graduation in the size and shape of the bill 

 from the heavy hooked beak of the Great black -backed gull, to the slender, 

 nearly straight bill of Bonaparte and Sabine gtills; and among the terns 

 from the ponderous beak of the Caspian tern and the gull-like beak of 

 Gelochelidun to the slim and delicate bill of the Black tern. The tail is 

 nearly square in most gulls; in terns and some gulls it is forked. The 

 legs are short, especially in terns, the tibiae being bare for a short dis- 

 tance. The ,legs are placed near the center of the body, so that they 

 stand and walk with ease, carrying the body in a nearly horizontal posi- 

 tion. The plumage is long and dense on the breast so that they rest 

 lightly on the water, "swimming high" in comparison to divers or even 

 ducks. Gulls and terns are very uniform in coloration, being mostly white 

 with a darker mantle over the back and wing coverts, which ranges 

 from slaty black in marinus to pale pearl-gray in hyperboreus, 

 but is pure white in the Ivory gull. They have dusky or black 

 markings, of greater or less extent, on the primaries, excepting in 

 hyperboreus, leucopterus etc., where they are nearly pure 

 white. A great point is made of these markings in the determination of 

 species [see pi. 5, 6]. The molt occurs twice a year so that there is a slight 

 difference between the summer and winter plumages. Immature birds 



