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% ‘a er AVES. th Re 221 
_ P 4 v 
ey age 
both sexes resemble the former. When the adult male and 
female are of the same "a ie the pars ones have a livery 
peculiar to them. 
] The brain of Birds has the same general characters as that 
» of other Oviparous Vertebrata, but is distinguished by its very 
"great proportionate size, which often surpasses even that of 
3 this organ inthe Mammalia. ‘This volume principally depends 
upon tubercles, analogous to the corpora striata, and not upon 
the hemispheres, which are narrow and without circumvolu- 
_ tions. The cerebellum is tolerably large, and almost without. 
lateral lobes, being chiefly constituted by the vermiform pro- 
cess. 
“The: rings of the trachea are entire; there isa glottis at its 
bifurcation most commonly furnished with peculiar muscles, 
which is called the inferior larynx; this is the spot where 
the voice of birds is produced; the immense volume of air 
contained in the air sacs contributes to its strength, and the 
trachea, by its various forms and motions, to its modifications. 
The superior larynx, which is extremely simple, has but little 
» to do with it. 
The face, or upper mandible of Birds, consisting chiefly of 
their intermaxillaries, islengthened out behind into two arches, 
the internal of which is composed of the pterygoid and palatine 
bones, and the external of the maxillaries and jugals, both of 
> a rest on a movable tympanic bone, commonly called the 
“square bone, analogous to that of the drum of the ear; above, 
this same face is articulated with the cranium, or united to it 
by elastic laminz, a kind of union which always allows the parts 
some degree of motion. . 
. The horny substance which invests the two mandibles, per- 
' forms the office of teeth, and is sometimes so jagged as to re- 
semble them ; its form, as well as that of the mandibles which 
support it, varies extremely, and according to the kind of food 
used by each species. 
The digestion of Birds is in proportion to the activity of their 
life, and the force of their respiration. ‘The stomach is com- 
posed of three parts: the crop, which is an enlargement of 
& 
