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 tibiae 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 

 (Chenelopex 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. 



