974 SYSTEMATIC SYNOPSIS.— LONGIPENNES. 



Liinicoline affinities of Longipennes, as thus indicated by pterylosis, and further borne out by 

 various osteological characters, I see no necessity for removing the present order from its long- 

 wonted position next to Petrels, and not far from Auks. In former editions of the Key, I 

 made the Longipennes include two suborders, Gavice for Jaegers, Gulls, Terns, and Skimmers, 

 or " Slit- nosed Lougwings," and Tubinares for the Petrel group, or "Tube-nosed Long- 

 wings." But I remarked (p. 732) that Longipennes, as an order thus constituted, was "less 

 substantially put together than either of the two preceding " (Anseres and Steganopodes) , and 

 that " it is not certain that the order must not be broken up." I now find it much better to 

 raise my former suborders Gavice and Tubinares to ordinal rank, as has been already done in 

 the British Museum Catalogue of these birds, as well as by the A. 0. U. I make no change 

 in the composition or sequence of the two groups. 



Fuller external characters of the Longipennes or Gavice are : Bill oi moderate length, en- 

 tire, or furnished with a cere; upper mandible longer than, as long as, or shorter than tlie 

 under; culmen convex; commissure very large, cutting edges without lamellaj, symphysis of 

 inferior mandibular rami complete for a considerable distance, an eminence being formed at 

 their junction. No gnlar sac. Feathers usually extending farther on sides of upper mandible 

 than on culmen, and farther between rami than on sides of under mandible. Nostrils never 

 tubular, but linear or oval ; direct, pervious, lateral, opening on basal half of bill. Eyes of 

 moderate size, placed about over angle of mouth. Wings long, broad, strong, pointed, with 

 little or no concavity. Primaries very long, more or less acute, the 1st developed one the longest, 

 the rest rapidly graduated. Secondaries numerous, short, broad, with rounded or excised tips. 

 Legs placed well forward, more or less perfectly ambulatorial. Thighs entirely covered and 

 concealed. Tibiae projecting; feathered above ; a considerable portion below naked, covered 

 with more or less dense, sometimes reticulated, skin. Tarsi of moderate length or rather short ; 

 compressed ; rather slender ; anteriorly transversely scutellate, posteriorly and laterally reticu- 

 late. Anterior toes of moderate length ; middle one usually about equal to tarsus ; outer shorter 

 than middle, intermediate between it and inner ; scutellate superiorly ; all of normal number of 

 segments (3, 4, 5). Hallux present; very small, short, elevated above plane of other toes; 

 entirely free and disconnected ; of the normal number of segments (2) — except in Rissa. Webs 

 extending to claws ; their surfaces finely reticulated, their edges usually more or less incised, 

 sometimes rounded. Claws fully developed, compressed, curved, more or less acute ; edge of 

 middle dilated, but not serrated. Tail very variable. Body generally rather full, and some- 

 times slender. Neck rather long. Head of moderate size. Plumage soft, close, thick ; its 

 colors simple — white, black, brown, or pearl- blue predominating; bright tints hardly found, 

 except on bill or feet, or as a temporary condition ; sexes alike in color, but plumage varying 

 greatly with age and season. Eggs generally 3, light-colored, with numerous heavy black 

 blotches. Nidification normally terrestrial ; reproduction altricial ; young ptilopaedic and nidi- 

 colous. Eegimen chiefly piscivorous. Habitat fluviatile, lacustrine, and maritime rather than 

 pelagic. 



The birds thus characterized may be regarded as forming one family with four subfamilies, 

 as in former editions of the Key ; or divided into two, three, or four families. The A. 0. U. 

 has Stercorariidce, LaridcB (with subfamilies Larince and Sternince), and Rhynchopidce. In 

 view of the anatomical characters which I first pointed out in 1863, I am now inclined to rec- 

 ognize two families, Stercorariidce and Laridce, the latter with three subfamilies, Larince, 

 SternincB, and Rhyndiopince ; and such is the course adopted by Howard Saunders, the latest 

 monographer of the Longipennes or Gavice (Cat. B. Brit. Mus. xxv, 1896, p. 3). 



Analysis of Families and Subfamilies. 

 Cceca very long ; sternum single-notched. 



Bill cered, epignathous. Tail square, with long-exserted middle feathers. Webs full ; claws raptorial. (Skuas. ) 



Family Stercorariid^ 



