BIRDS—LARINAE—LARUS. 841 
Eight well marked genera, however, included in this sub-family, are found in the United 
States. 
1. Larus.—Of large and medium size; bill strong and hooked at tip; mantle generally 
light colored ; head white ; tail nearly even. 
2. Buasrpus.—Of middle size ; bill long and rather slender; head white ; rest of plumage 
dark ; tail slightly emarginate. 
3. CurolcocEPHALUs.—Size medium and rather small; bill moderate or slender; the head 
enveloped in summer with a dark colored hood ; tail generally even. 
4, Rissa.—Medium size; bill long and rather strong; colors light; hind toe short or 
toler 
rudimental ; tail even. 
5. Pacopurta.—Of middle size; bill short and very strong ; mantle light; tarsi rather short ; 
webs indented, 
6. Raoposteru1a.—Small in size; bill short and rather slender; mantle pale; neck encircled 
with a black collar ; tail uniform. 
7. Creacrus.—Medium size; bill very strong and much curved; mantle grayish white ; 
tail deeply forked. 
8. Xema.—Of small size ; bill short and rather slender; mantle bluish gray ; tail moderate 
and forked, 
LARUS, Linnaeus. 
Larus, Linn, Syst. Nat. 1735. 
Cu.—Bill strong and laterally compressed ; the culmen straight at the base and curved at the end; nostrils lateral and 
linear, placed near the centre of the bill; wings pointed ; first quill longest; tail even; tarsi nearly the length uf the middle 
toe; feet with a full web ; hind toe elevated. The largest of the family are found in this genus; none very small. 
There are several well marked groups in this genus, but not sufficiently different for generic 
distinction. They may be arranged in the following manner : 
A. Levucus, Bp.—Large and powerful in form; the upper plumage very light in color; 
primary quills white, or of the same color as the back. 
Mantle grayish blue; primaries white at the end for a considerable space......L. glaucus. 
Mantle greyish blue; primaries of the same color as the back, except the tips, which 
ECE WDC renereeceosenstecev cokes Seeeitess selssisccescemetecte et oascecdeices ceeeenaecoreses L. glaucescens. 
Mantle pale grayish blue; primaries of the same pbloek at the base, terminating largely 
swibhmwihii tees cosvavedcersesSrosesesececercoees Stich bob cdodandnuaanentetaededeast sesoscee L. leucopterus. 
Mantle grayish blue; primaries ash gray; the tips marked with a rounded white 
IS] UC loo dccco9) 2500000 fb Cc OSS GOOoCACUBECDONOCOa acs un Hn SadaAtc. t0n COOUuS ROSES ORaanUnSEE L. chalcopterus. 
B. Domrntcants, peice eo the upper plumage dark slate color ; primaries black near 
the end ; tips white....... Scogoapadten :achn 580008 Sone auch boto coocuaEose AD HbadagacSnannanceot Rea LT. marinus. 
C. Larores, Brehm.—Large ; the mantle pearl or bluish gray ; primaries marked near the end 
with a black band ; tips white. 
Mantle pale bluish gray; primaries black near the end, with the tips white...Z. argentatus. 
Mantle bluish gray ; primaries crossed near the end with black ; tips white. 
L. californicus. 
Mantle dark bluish gray ; primaries black near the end, with the tips white. 
L. occidentalis, 
August 25, 1858. . 
106 b 
