174 REPTILES AND BIRDS. 
genus Falco the bill is shorter than the head; the upper mandible, 
which is furnished at the base with a bare coloured skin, of a peculiar 
dense texture, called the cere, in outline is slightly convex as far 
Fig. 60.—Bill of Eagle. 
as the edge of the cere (Fig. 60), then curved so as to form about 
the third of a circle, and is evidently destined, in connection with 
its formidable claws, to tear its prey. 
Fig. 61.—Bill of Toucan, 
In the Toucans Ramphastide the bill is half a foot long, hollow 
within, thin, and nearly transparent; and the mandibles are so dis- 
posed as to combine, with their great bulk, strength and lightness, 
and assisting by their digestive power to assimilate both animal and 
Fi (i 
may 
Fig. 62.—Bill of Cormorant. 
vegetable food (Fig. 61). In the Pelicanide, as in the Common 
Cormorant, the bill is long, straight, and compound; the upper 
mandible curved towards the point, the lower compressed; the 
base inserted in a small membrane which extends under the throat. 
In the back part of the head is an additional bone (Fig 62, a), 
i 
