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LARIDH, GULLS.—GEN. 281-5. 313 
ordinary Californian bird is distinguished by the above particulars ; but connects 
directly with argentatus by the North Pacific strain (ZL. borealis Branpr; Barrp, 
Trans. Chicago Acad. i, 324), and the Siberian bird (L. cachinnans Paty.; L. 
argentatus var., MipDDENDORF, SCHRENK). 
Ring-billed Gull. Adult plumage precisely like that of the last species, 
and its changes substantially the same; bill greenish-yellow, encircled with 
a black band near the end, usually complete, sometimes defective, the tip 
and most of the cutting edges of the bill yellow; in high condition, the 
angle of the mouth and a small spot beside the black, red; feet olivaceous, 
obscured with dusky or bluish, and partly yellow; the webs bright chrome. 
(Observe the coloration of the feet in this and in californicus, as compared 
with argentatus.) Notably smaller than argentatus; length usually 18-20 
inches ; extent about 48 ; wing about 15; bill wnder 2, and only about 4 deep 
at the protuberance; tarsus about 2, obviously longer than the middle 
toe. N. Am., abundant and generally distributed. LZ. delawarensis Orv, 
Guthrie’s Geog. 2d Am. ed. ii, 319; Lawr. in Bp., 846; Z. canus Nur., il, 
299; L. zonorhynchus Ricu., F. B.-A. ii, 421; Nurr., ii, 300; Aup., vii, 
152, pl. 446. Cours, 1. c. 302. Reeth eer ae oe Pa een un DHT AW AEN SIGs 
Var. catirornicus. Apparently larger than ordinary delawarensis, and sometimes 
nearly equalling argentatus, averaging perhaps 22 inches; bill about 2, the black 
band probably never perfect, the red spot more obvious ; feet colored as in the last ; 
tarsus 24, yet not, or not obviously, longer than the middle toe and claw. Tn all the 
adult birds observed, the white spot on the 1st primary had enlarged to occupy the 
whole end of the feather for about 2 inches; while the subapical spot on the 2d was 
large—a state I have not observed in typical delawarensis. Arctic and Western 
America, abundant. Lawr., Ann. Lye. N. Y. 1854, 79, and in Bp., 846; Cours, 
1. c. 300 (excl. syn.). (Type specimen examined.) 
American Mew Gull. Small; length 16-18 inches; extent about 40; 
wing 13-14; bill 14, slender, its depth hardly or not over 3; tarsus about 
equal to the middle toe and claw, both about 13. Bill bluish-green, yellow- 
tipped, without any red or black; feet dusky bluish-green, webs yellow. 
Mantle considerably darker than in delawarensis. Arctic and Western N. 
Am., in the interior and along the Pacific Coast to California ; I am not 
aware that it occurs on the Atlantic, or anywhere in the United States east 
of the Rocky Mountains ; Nuttall and Bonaparte seem to refer to the pre- 
ceding species in giving this range. It will be seen at once to be different 
from any of the foregoing: and it appears to show constantly some slight 
discrepancies from the European Z. canus. ZL. canus (adult) and L. 
brachyrhynchus (young—type specimen examined) Ricu., F. B.-A. ii, 
420, 422; Nurr., ii, 299, 301; Cours, J. c. 302; Rissa septentrionalis 
(adult) and Z. suckleyi (young —types of both examined) Lawr., Ann. Lye. 
N. Y. vi, 265, 264, and in Bp., 854, 848. CANUS var. BRACHYRHYNCHUS. 
+} Feet black, stout, rough, with short tarsi and excised webs. (Pagophila.) 
Ivory Gull. Adult plumage entirely pure white, the shafts of the 
primaries yellow; bill yellow, more or less extensively greenish or dusky 
toward the base; feet black. Young: more or less spotted and patched 
KEY TO N. A. BIRDS. 40 
