ALCADjB. LARID^. 
373 
Rynchops, Linn. Bill excessively compressed: the upper 
mandible much shorter than the under. 
R. niger. Wils. 60. f. 4. melanuriis. Part 5. No. 175. 
Gavia, Brisson. General structure of Sterna ; hut the 
tail is even or rounded. 
G. leucoceps. PI. linl. 997- 
Labus, Linn. Gull. Bill much compressed, straight, 
hut the outer half of the culmen much curved. Gonys 
strongly angulated. Wings very long. Tail short, 
even. Feet moderate. Tarsi as long or longer than 
the middle toe. Hind toe very short. Typical. 
L. tridactylis. PI. Enl. 387. Sabini. Lin. Tr. xii. pi. 29. 
ridibuiuius. Selby, pi. 92. 
Lesthis, llliger. Jager. Bill moderate ; thehasestraight, 
cylindrical, and covered with a cere, beyond which 
the culmen is arched, and the tip hooked. Gonys an- 
gulated. Feet slender, naked above the knee. Claws 
large, much curved. Tail graduated ; the two middle 
feathers lengthened. Raptorial. 
Cataraetes. Selby, pi. 100. Richardsoni. N. Z. pi. 73. 
Diomeuia, Linn. Pctreh. Bill straight ; the end abruptly 
hooked. Nostrils tubular, opening in front, with the 
sides prominent and convex. Rasorial. 
Procellaria. Bill shorter than the head. Tips of the 
under mandible straight and truncated. No hind toe, 
but a short claw. Nostrils simple. 
P. Capensis. Edwards, pi. 90. 
Dtomcdio, Linn. Albatross. Billmuchlonger than the 
head: the under mandible truncated. Nostrds simple. 
No hind toe or claw. 
D. exulans. PI- Enl. 237. 
Halodroma, llliger. BUI very short : the under man- 
dible truncated at the tip. Nostrils iiiternaUy m 
double tubes. Feet short. No hind toe or claw. 
Chin with a dilatable pouch. Natatorial. 
H. urinatrix. PI. Col. 517- 
Thalassidroma, Vigors. Bill moderate. Both mandibles 
B B 3 
