of the Solvent Glands, &c. 397 
the mucus of the stomach comes under this description, except 
what is now stated. 
In birds that live upon fish, and sea insects with crustaceous . 
coverings, as the sea gull, (Larus canus), the gizzard has 
a horny cuticular lining, and the solvent glands are in the 
same situation as in the genus falco. In the gizzard were 
found the scales of small fishes. The appearance of the 
solvent glands and gizzard are shewn in the annexed 
engraving. 
In those birds that live on land insects, some of whose 
coverings are soft, others hard, there is a difference in the 
structure of the digestive organs from what has been described. 
The solvent glands are placed in a triangular form in the car- 
diac cavity, which is very large, and immediately under it is 
a small gizzard with a horny lining. Of this kind is the wood- 
pecker, (Picus minor). A representation of the parts in this 
bird is annexed. 
There is still another variety in the structure of these organs. 
In the little auk, the (Alca Alle), the solvent glands are 
spread over a greater extent of surface than in any other 
bird that lives on animal food, and the form of the digestive 
organs is peculiar to itself. The cardiac cavity appears to be 
a direct continuation of the oesophagus, distinguished from it 
by the termination of the cuticular lining, and the appearance 
of the solvent glands. This cavity is continued down with very 
gradual enlargement below the liver, and is then bent up to 
the right side, and terminates in a gizzard : when the cavity is 
laid open, the solvent glands are seen at its upper part, every 
where surrounding it, but lower down they lie principally on 
the posterior surface, and where it is bent upwards towards 
mdcccxii. 3 F 
