LARIDA, — CXXVIIL. 219 
329. STERCORARIUS Brisson. (Lat., scavenger.) 
643. S. pomarinus (Temminck). Pomarine JzGER. Chiefly 
blackish, colors varying with age; middle tail feathers broad to 
the tip, projecting about 4 inches. L.20. W.15. T.9. B. 1}. 
Arctic, S. in winter to N. J. (Eu.) (aéya, flap; pis, nose.) 
644. S. parasiticus (L.). Parasitic Jzcer. Dark brown; 
middle tail feathers acuminate, projecting 4 inches. L. 20. W. 
13. T.5}. B.1}. Arctic, S. in winter toN. Y. (Eu) 
645. S. longicaudus (Vieillot). Lone-raiLEp J&GER. Sooty 
black; tail feathers filamentous, projecting 8 or 10 inches. L. 22. 
W.12, 7.13. B.14. Arctic, S. in winter. (Eu.) 
Famity CXXVIII LARIDAi. (THE Gutts.) 
Long-winged swimmers, with the nostrils not tubular. Bill usu- 
ally long, horny, not serrate nor lamellate; nostrils developed ; no 
gular pouch. Feet palmate; tibia feathered ; legs near centre of 
equilibrium; hind toe elevated, small, often wanting. Wings very 
long and pointed. Tail well developed. General color usually 
white, with a darker mantle of a pearly bluish tint, and commonly 
with some black markings. Sexes alike in color, but the plumage 
varying much with age and season. Genera about 12; species 90; 
abounding about all large bodies of water, and of remarkable 
power of flight. Altricial; food chiefly fishes. 
u. Bill more or less hooked ; (general color chiefly white, with a darker, 
bluish, grayish, or slaty mantle); gulls. (Larine.) 
6. Tarsus rough or serrate behind; taileven. . . . . PaGopHima, 330. 
bb. Tarsus nearly entire behind. 
c. Hind toe rudimentary or wanting, with minute claw or none; tail 
slightly emarginate. . . ee el se . Rissa, 331. 
cc. Hind toe small, but with a panfaot che 
d. Taileven.. . . . . 2 2 6 « © «© « «© © © ~©6LARUS, 882. 
dd. Tailforked.. . . " - . . XeEMma, 333. 
aa. Bill not hooked, the mandilse: even; tail decay forked (in our species). 
(Sternine.) 
e. Tail much more than 3 wing, its outer feathers narrow and pointed; toes 
well webbed. (Color chiefly white, with a black cap in full plumage, 
and the quills dusky with a long white stripe.) 
J. Bill stout, its depth at base equal to} culmen. GELOCHELIDON, 334. 
Jf. Bill slender, its depth at base not } its length. . . . STERNA, 335. 
ee. Tail little more than } wing, its outer feathers broad and rounded; 
toes scant-webbed; colors dark. . . . » HYDROCHELIDON, 336. 
330. PAGOPHILA Kaup. 
646. P. alba (Gunner). Ivory Guiz. Adults pure white ; 
young spotted; feet black. L. 16 to 20. W.13. B. 13. Arctic, 
rarely to U. S., in winter. (Eu.) 
