152 OUR DOMESTIC FOWLS. 



tlie conlour of the limbs, their gait on the 

 ground is waddling. The three anterior toes 

 are united by webs, but the posterior toe is 

 free, yet often lobated, or paddle-shaped. The 

 bill is large, and more or less depressed, some- 

 times very broad ; both mandibles are covered 

 with a sort of leathery skin abundantly sup- 

 plied by nerves of touch ; at the base of the 

 upper mandible there is a sort of cere, (in 

 which the nostrils are placed,) in some more 

 extensive than in others, and at the tip of 

 the upper mandible is a sort of flat incurved 

 hard nail, (called dertrum.) Along the edges 

 of each mandible extends a series of laminated 

 processes, sometimes remarkably developed and 

 in close array, these serve as strainers, enabling 

 the bird to sift the ooze or mud through the 

 beak, and retain worms, insects, and vegetable 

 matters. The tongue is large, fleshy, sensitive, 

 and furnished along its edges with filamentous 

 pectinations, which aid the beak in the reten- 

 tion of food. The eyes are defended by a 

 strong membrana nictitans, and both sight and 

 hearing are acute. The voice is hoarse, harsh, 

 and clanging : in. many species, there is a sort 

 of osseous drum at the lower portion of the 

 windpipe, in some there are certain dilatations, 



