372 ON THE CLASSIFICATION OF BIRDS. 
petes ; but the under mandible is straight to the end, 
where it is truncated. Wingsshort. Tail hard, and 
rounded. 
Cormoranus. Selby, pl. 84. —cristatus. Ib. pl. 86. 
Pexicanus, Linn. Pelican. Bill long, straight, depressed ; 
the tip greatly hooked. Chin naked, forming an ex- — 
tensible pouch. Middle claw entire. Rasorial. 
- P. onocrotalus. Pl. Enl. 87. 
Dysporvus, Illiger. Gannet. Bill entirely straight ; the 
base thick ; the tip acute and compressed ; the upper 
mandible suleated. Culmen convex. Wings long. 
Middle claw serrated. Tenuirostral. 
D. bassanus. Selby, pl. 86*, 87. 
Susram. LARIDZ®. Gulls. 
Feet lengthened, formed both for walking and swim- 
ming. | 
Sterna. Terns. Feet short. Wings and tail exces- 
sively long ; the latter generally forked. Bill straight 
at the tip. Fissirostral. 
Sterna, Linn. Bill slender, very straight : the culmen 
and gonysequally curved towards the tip. Commissure 
straight. Nostrils basal, long, linear. Feet small, 
weak. Tarsus much shorter than the middle toe. 
Hinder claw curved. 
S. Hirundo. Selby, pl. 90. f. 1. ihm Ib. pl. 91. ; 
Thalassites, Sw. Bill strong: the culmen curved 
from the base: the gonys short, and hardly angulated : — 
the commissure curved. Nostrils towards the middle 
of the bill, oval. Feet strong. Tarsus longer than _ 
the middle toe. The hinder claw straight. 
T. magnirostris., Spix, pl. 104. 
Pheton, Linn. Tropic-bird. Bill as in the last, but the 
margins dentated. ‘Tail short, but the two middle 
feathers excessively long and filiform. Feet very 
short, natatorial: all the toes connected by a psi 
brane. J 
P. phenicurus. Pl. Enl. 979. 
