844 U. S. p. R. R EXP. AND SURVEYS — ZOOLOGY — GENERAL REPORT. 



LARUS MARINUS, Linnaeus. 



The Great Black-backed Gull. 



Larua marinus, Linn. Syst. Nat. 1, 1766, 225.— Bonap. Syn. 1828, No. 303 — Nutt. Man. II, 1834,308.— Acd. Birds 



Am. VII, 1844,172: pl.ccccl. 

 Dominicanus marinus, Bruch, Cab. Jour. 1855, 280. — Bon. Cons. Av. II, 1856, 213. 



Sp. Ch. — Jldnll. The head, neck, entire under p'umage, upper tail coverts, and tail are pure white ; the back and wings are 

 of a dark slate color ; the primaries are deep black, largely tipped with white, as are the e.xtremities of most of the quills ; the 

 bill is camboge yellow, with an orange red spot near the end of the lower mandible ; legs and feet pale yellow. 



Length about 30 inches ; wing, 20 ; tail, 9 ; bill, 2 10-12 ; tarsus, 3 2-12. 



young-. Head, rump, and under plumage grayish while with streaks of light brown ; back and wings mottled with brownish 

 ash and grayish white ; primaries blackish brown, having the tips edged with white ; tail white, spotted with brown and having 

 a broad subterminal band of the same color ; bill brownish black, yellowish at the base ; legs and feet yellow. 



Hab. — North Atlantic, Labrador ; as far south as Florida in winter. 



LARUS ARGENTATUS, Briinnicli. 



The Herring Gull; The SUvery Gall. 



Larus argentatus, Brcnn. Cm. Bor. 1764, 44.— Bonap. Syn. 1828, No. 300.— Ndtt. Man. II, 1834, 304.— Aud. Birds 



Am. VII, 1844, 163; pi. ccccxlviii. 

 Laroides argentatus, Bruch, Cab. Jour. 1855, 282. — Bon. Cons. Av. II, 1856, 218. 

 Laroides argcntatoides. Rich. F, B. A. II, 1831, 417. 



Sp. Ch. — Adult. Head, neck, under parts, rump, and tail, pure white; back and wings light pearl blue; the first six 

 primaries are marked towards their ends with black, which begins on the first at about half its length from the end, and is 

 rapidly lessened on the others until it becomes only a sub-terminal bar on the sixth ; the primaries all tipped with white ; on 

 the first quill it is about an inch and a half in extent, crossed near the end with a black bar, on the second quill there is a round 

 white spot on the inner web near the end ; secondaries and tertiaries broadly ending with white ; bill bright yellow, with an 

 orange red spot near the end of the lower mandible ; legs and feet flesh colored. 



Length of male, 23 inches; wing, 18; tail, 7^; bill along ridge, 2^ ; depth at angle, \%; tarsus, 2^. Female a little 

 smaller than the male, but similar in plumage. 



Young mottled with light grayish brown and dull white; primaries blackish brown; bill brownish black, yellowish at the base. 



Hab. — Atlantic coast from Texas to Newfoundland ; western States ; Ohio and Mississippi rivers. 



L. argcntatoides, Richardson, is made a distinct species by both Bruch and Bonaparte. 

 Bruch describes it as differing from L. argentatus " merely by its paler gull blue." 



Bonaparte (Cons. Av. II, 1856, 218) makes it the bird described by American writers, and 

 Bays, " distinct from L. argentatus, with the back paler, smaller, 20 inches in length, tarsi 2 

 inches." 



I have specimens of the species herein described as L. argentatus, which vary in size from 22 

 to over 26 inches, but cannot discover sufficient characteristic differences to form two species. 



There is great variation in the size of different individuals in the gull family, so much so that 

 it would not be safe to make dimensions a guide for specific distinction. 



Mr. McGillivray, in his " History of British Birds," under L. argentatus, notices this great 

 disparity in size, and remarks upon the probable identity of the EuroiJean and American bird 

 as follows: "Having carefully examined specimens from various parts of North America, I 

 find them clearly to belong to the same species." 



