856 
U. S. P. R. R. EXP. AND SURVEYS—ZOOLOGY-GENERAL REPORT. 
Plumage entirely white; bill bright yellow, dusky at the base; tarsi moderate. 
P. eburneus. 
Plumage more purely white than in the above species ; bill short, yellow, with the 
point orange ; tarsi short.P. bracliytarsi. 
PAGOPHILA EBURNEA, Kaup. 
Tile Ivory Gull. 
Lameburneus, Gmel. Syst. Nat. I, 1788, 596.— Bonap. Syn. 1828, No. 297.— Rich. & Sw. F. B. A. II, 1831,419 • 
Nutt. Man. II, 1834, 301.— Aud. Birds Am. VII, 1844, 150 ; pi. ccccxlv. 
Pagophila eburnea, “ Kaup,” Bruch, Cab. Jour. 1855, 286.— Ron. Cons. Av. II, 1856, 230. 
Larus canilidus, Farr. Fauna Groenl. 67. 
Gctvia nivea, Brehm. 
Sp. Ch. — Mult. The entire plumage is pure white ; bill bright yellow, dusky at the base ; margins of the eyelids vermilion; 
iris brown ; legs and feet black. Length about 19 inches ; wing, 13| ; tail, 6j ; bill, 1 5-12 ; tarsus, 1 7-12. 
Hah .—Coasts of Arctic America, Labrador, Newfoundland. 
There are no specimens of this species in the collection. 
In the cabinet of my friend J. P. Giraud, jr., esq., are two fine specimens, which originally 
belonged to Mr. Audubon. 
PAGOPHILA BRACHYTARSI, Hollboll. 
Tile Slioi’t-leggecl Gull. 
“ Pagophila bracliytarsi, Hollb.” Bruch, Rev. Lar. in Cab. J. 1855, 287. 
“ Pagophila niveus, Brehm,” Bonap. Cons. Av. II, 1856, 230. 
Bruch says of this species, “ resembles P. eburnea in all its parts, but is smaller ; the wings 
extend two lines beyond the tail.” 
Bonaparte makes it identical with L. niveus , Brehm., to which he gives precedence, and 
describes it as similar to P. eburnea , but whiter and handsomer : as being larger than that 
species, and having a shorter bill, which is yellow, with the point orange. 
Hab. —Greenland. 
There are no specimens in the collection. 
RITODOSTETIIIA, Macgillivray. 
Rliodostethia, Macgill. Man. of Orn. II, 1842. 
Ch. —Bill short and slender ; upper mandible straight for half its length, then slightly curved to the tip, which is very narrow; 
prominence on the lower mandible small; wings long and pointed ; tail wedge-shaped ; tarsi rather strong; toes united by a 
full web, hind small and elevated. 
But a single species in this genus, found in the Arctic regions; its most striking characteristic 
is the cuneate form of the tail. 
RHODOSTETHIA ROSEA, Bonap. 
Tlie Wedge-tailed Gull. 
Larus roseus, Jard. & Selby, Ills, of Orn.-, pi. xiv. 
295.— Aud. Birds Am. VII, 1844, 130. 
Rliodostethia rosea, Bruch, Cab. Jour. 1855, 278.— Bon. Cons Av. II, 1856, 230. 
Larus rossii, Rich. Parry 2d Voy. App. 1825, 359. —Rich. & Sw. F. B. A- II, 1831, 427. —Nutt. Man. II, 1834, 
