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 ; hill strong and hooked at tip ; mantle generally 
light colored ; head white ; tail nearly even. 
2. Blasipus. —Of middle size ; hill long and rather slender ; head white ; rest of plumage 
dark ; tail slightly emarginate. 
3. Chroicocephalus. —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 ; hill long and rather strong ; colors light ; hind toe short or 
rudimenlal ; tail even. 
5. Pagophila. —Of middle size ; bill short and very strong ; mantle light; tarsi rather short ; 
webs indented. 
6. Rhodostethia. —Small in size ; hill short and rather slender ; mantle pale ; neck encircled 
with a black collar ; tail uniform. 
7. Creagrus. —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. 
Ch.—B ill 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 of 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. Leucus, 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. glaucus. 
Mantle greyish blue ; primaries of the same color as the back, except the tips, which 
are white. L. glaucescens. 
Mantle pale grayish blue ; primaries of the same color at the base, terminating largely 
with white. L. leucopterus. 
Mantle grayish blue ; primaries ash gray ; the tips marked with a rounded white 
spot. L. chalcopterus. 
B. Dominicanus, Bruch.—Large ; the upper plumage dark slate color ; primaries black near 
the end ; tips white. . L. marinus. 
C. Laroides, 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... L. 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 
