34 BILE 
unpaired piece being more or less separated from the lateral 
pieces. In the majority of birds the horny covering forms one 
coherent sheath. 
Frequently the edges of the mandibles and of the maxille are 
serrated to secure a firmer hold upon the food, for instance in 
Toucans. In the Anseres these tooth-like serrations are arranged in 
the shape of numerous transverse lamellae, and hence the name 
“ Lamellirostres,” which, especially in the Shoveler, form an elaborate 
sifting apparatus. 
The bill of the Flamingos is likewise furnished with such sifting 
lamelle ; the two halves of the under jaw are considerably enlarged, 
so that the comparatively narrow upper jaw closes upon a wide 
cavity. In addition to this the whole bill is bent downwards, 
in some species rather abruptly ; these long-necked birds being thus 
enabled to sift the soft mud of lagoons with their bill in an inverted 
position, the dorsal surface of the bill being turned towards the 
bottom. Undoubtedly this most peculiar bill is a secondarily 
acquired character, referable to the mode of feeding, which again 
is connected with the long neck and legs. This view is 
strengthened by the fact that very young Flamingos still have 
straight and short bills, which very gradually and only compara- 
tively late assume the final shape. 
Fine sifting lamellz occur also in Prion (WHALEBIRD), and as a 
dense brushlike mass on the inside of the premaxillary region in 
Anastomus. The jaws of this genus have the further peculiarity 
that they do not shut completely, being slightly curved in opposite 
directions. 
In the Spoonbilled Sandpiper, Hwgynorhynchus pygmexus, the 
end of the upper and lower bill is of a peculiar spatulate and heart- 
shaped form. 
The broad and flattened spatulate bill of the SPOONBILLS, the 
boat or shoe-shaped bill of the Whale-headed Stork, Balzxniceps, and 
of the Cancroma (BOATBILL), the long bills of the Ibis and the 
Whimbrel, curved downwards, and upwards in the Avoset, need no 
further comment but that they all are illustrations of the adapta- 
tion to a special mode of life, and therefore not necessarily indica- 
tive of relationship, as rather analogous than homologous structures. 
The beak of Parrots is extremely strong, and well adapted 
to the breaking open of nuts by sheer force. ‘The mandible ends 
in a transverse blunt edge, which presses against a corresponding 
horny prominence of the upper beak. In the large Muicroglossa 
(CocKATOO), which lives on the stone-hard fruit of the kanari-tree 
(Canarium commune), the beak bears a striking resemblance to a 
sledge-hammer. ‘Transverse ridges, like those of a file, are common 
in front of the prominence of the upper jaw, the bird using them 
as a rasp—no Parrot swallowing anything but absolutely com- 
