288 NATATORES. ANATINA. 
tomia of the upper. Both mandibles having prominent trans- 
verse lamellae. Nasal fosse near the base of the bill ; nostrils 
oval, lateral, pervious. 
Wings of mean length, acute, tuberculated ; with the se- 
cond quill-feather the longest. 
Legs of mean length, with the tibize naked for a short space 
above the tarsal joint. Tarsus rather longer than the mid- 
dle toe. Toes four, three before and one behind; the front 
ones rather short, and entirely webbed ; hind toe barely 
touching the ground with the tip of the nail. Claws slightly 
hooked, the inner edge of the middle one being dilated. 
The Shieldrakes are distinguished from the other nearly 
allied genera by the form and curvature of the bill. From 
the length and position of their legs (being placed almost in 
the centre of the body), they are active upon land, walking 
and running with apparent ease; and their general contour 
is handsome. Their alliance with the Geese seems to be 
maintained by the intervention of the Egyptian Goose 
(Chenelopea Egyptiaca), which, in many points, both of out- 
ward form and internal structure, shews a decided approach 
to this genus. They are the inhabitants of the coast, and 
also of the rivers and lakes of the interior, feeding on vege- 
tables, seeds, insects, and molluscous animals. Their nests 
are made in the clefts of rocks, in the deserted burrows of 
rabbits, &c., and sometimes in the hollows of decayed trees. 
The trachea of the male birds possess a labyrinth (ampulla) 
at the divarication, consisting usually of two membranous 
bladders of a very delicate texture. The sexes are nearly 
similar in plumage. 
