844 U. Ss. P. R. R EXP.. AND SURVEYS—ZOOLOGY—GENERAL REPORT. 
LARUS MARINUS, Linnaeus. 
The Great Black-backed Gull. 
Larus marinus, Linn. Syst. Nat. I, 1766, 225.—Bonap. Syn. 1828, No. 303 —Nurr. Man. II, 1834, 308.—Avp. Birds 
Am. VII, 1844, 172: pl. ececl. 
Dominicanus marinus, Brucu, Cab. Jour. 1855, 280.—Bown. Cons. Av. II, 1856, 213. 
Sp. Cu.— Adult. The head, neck, entire under plumage, 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 extremities of most of the quills; the 
bill is gamboge 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 white 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, Briinnich. 
The Herring Gull; The Silvery Gull. 
Larus argentatus, Bri:nn. Orn. Bor. 1764, 44.—Bonap. Syn. 1828, No. 300.—Nurr. Man. II, 1834, 304.—Avp. Birds 
Am. VII, 1844, 163; pl. eecexlviii. 
Laroides argentatus, Brucn, Cab. Jour. 1855, 282.—Bon. Cons. Av. II, 1856, 218. 
Laroides argentatoides, Ricu. F. B. A. 11, 1831, 417. 
Sp. Cu.—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 
Tapidly 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, 32; tarsus, 23. 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. 
LI. argentatoides, 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 
says, ‘‘ distinct from ZL. argentatus, with the back paler, smaller, 20 inches in length, tarsi 2 
inches.”’ 
I have specimens of the species herein described as Z. 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 ZL. argentatus, notices this great 
disparity in size, and remarks upon the probable identity of the European 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.’’ 
