548 CLASS AVES. 



but in some they are elongated in a proportion nearly equal 

 to that in the passeres in general. Their skin is scaly, as is 

 that of the toes ; the wings are usually short ; the tail is more 

 or- less long, and assumes a variety of forms ; the colours of 

 the plumage are almost always brilliant. 



The head of these birds is voluminous, and of a rounded 

 form; the bill varies in its bulk, relatively to that of the head 

 and body, in the different species : thus, in the long-tailed par- 

 rakeets, which the French naturalists term perruches, the bill 

 is rather small, being, measured in its curve, but a third of 

 the length of the head. In the parrots proper, it is nearly one- 

 half that length ; while in the maccaws and the microglossa, 

 it is as long as the head itself. The upper mandible is always 

 the most powerful, and it often entirely conceals the lower. 

 It is articulated on the forehead, so as to admit of considerable 

 mobility ; for it forms with it, very sensibly, a re-entering 

 angle, when the parrot opens its bill and gapes. In general, 

 the back of this mandible is rounded, though in one species it 

 is carinated, or keel-formed. Its point is very sharp, though 

 less so than in the beak of the accipitrine birds, and prolonged, 

 more or less, underneath. Its edges are trenchant, and occa- 

 sionally furnished with a sinuosity, or a tooth, which reminds 

 us of the beak of the falcon. The under facet of this same 

 part is vaulted, slightly arched from back to front, and its 

 superficies is furnished with numerous stride, parallel to each 

 other, and formed like a V, or a chevron, with the point for- 

 wards. The use of these appears to be, to render the surface 

 against which the aliments rest, less slippery, while they are 

 divided by the under mandible. This under mandible is 

 short, sometimes joining only the base of the upper, and in- 

 capable of closing the bill entirely. It is also rounded, very 

 slightly compressed, and trenchant at the end, which alone is 

 used for the division of the food. These two portions of the 

 bill, formed of a very hard and thick homy substance, are 



