856 U. S. p. E. E. EXP. AND SUEVEYS —ZOOLOGY — GENEEAL EEPOET. 



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. brachytarsi, 



PAGOPHILA EBUENEA, Kaup. 



The Ivory Crtill. 



Laru. eburneus, Gmel. Syst. Nat. 1, 1788, 596.— Bonap. Syn. 1828, No. 297.— Rich. & Sw. F. B. A. 11, 1831, 419.— 



NuTT. Man. II, 1834, 301.— Aud. Birds Am. VII, 1844, 150 ; pi. occexlv. 

 Pagophila eburnea, " Kaup," Eruch, Cab. Jour. 1855, 286.— Ron. Cons. At. II, 1856, 230. 

 Larus camlidus. Parr. Fauna Groenl. 67. 

 Gavia nivea, Brehm. 



Sp. Ch. — Jldult. The entire plumage is pure white ; bill bright yellow, dusky at the bDse ; mirgina of the eyelids vermilion; 

 iris brown ; legs and feet black. Length about 19 inches ; wing, 13j ; tail, 6j ; bill, 1 5-12 ; tarsus, 1 7-12. 

 Hab. — Coasts of Arctic America, Labrador, Newfoundland. 



There are no specimens of this species in the collection. 



In the cabinet of my friend J. P. Griraud, jr., esq., are two fine specimens, which originally 

 belonged to Mr. Audubon. 



PAGOPHILA BRACHYTARSI, Hollboll. 



TKe SlLort-legged Gull. 



" Pagophila brachytarsi, Hollb." Eruch, 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 mates 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. 



RHODOSTETHIA, Macgillivray. 



Rhodostethia, 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 AVedge-talled Gull. 



Larus roseus, Jard. & Selbt, Ills, of Orn. , pi. xiv. 



295.— Ann. Birds Am. VII, 1844, 130. 

 Rhodostethia 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.— Nctt. Man. II, 1834, 



