402 ORGANS OF DIGESTION. 



claws, feathers,, and other indigestible parts, are disgorged by 

 the mouth, without being allowed to pass through the alimen- 

 tary canal. This cavity however is entirely wanting in most 

 of the passerine, wading, and palmified birds, although sub- 

 sisting on the most dissimilar kinds of food; and it is scarcely 

 perceptible in the nocturnal birds of prey, or in the long- 

 necked struthious birds. 



The glandular follicles on each side of the small ventriculus 

 succenturiatus (129. A. B. c. c.) are mostly disposed in vertical 

 rows, and have their orifices directed downwards. They are 

 placed, like those of the crop, between the mucous and the 

 muscular tunics ; they are most numerous and complicated in 

 the granivorous birds, where they form ramified tubuli ; and 

 they are simple elongated follicles in the birds of prey. They 

 sometimes surround the whole cavity, or are confined to a 

 part of the surface, and their copious secretion is required, to 

 assist in digestion, from the deficient glandular structure of 

 the gizzard itself. These glandular follicles of the ventriculus 

 succenturiatus, or infundibulum, of birds are analogous in 

 position to the cardiac glands, so large in the wombat, the 

 beaver, and some other mammalia. 



These muscular parietes of the gizzard (129, A. d.) form 

 two strong digastric muscles, one anterior, the other poste- 

 rior, with white shining tendons, in most gallinaceous and 

 granivorous birds, and in many aquatic and other species. In 

 most rapacious and carnivorous birds, the parietes of all the 

 three gastric cavities are thin and highly extensible, and form 

 almost one continuous stomach, (129. B. b.c.d.) with slight 

 constrictions between its parts. The thin membranous giz- 

 zard however of these birds presents a distinct anterior and 

 posterior central tendon, (129. B. c?.) analogous to those of 

 the two ordinary digastric muscles, (129. A. d.}, and from 

 which the muscular fasciculi, more or less developed in dif- 

 ferent species, radiate to the margins of the cavity. When this 

 third gastric cavity is provided with strong muscular parietes, 

 as in the gallinaceous birds, its internal epidemic lining forms 

 a thick coriaceous dense coat, to protect the soft parts from 

 laceration, and to enable them to act with effect upon their 

 heterogenous contents. From the want of teeth in the mouth 

 to act upon their hard food, these granivorous birds convey 

 pebbles and other dense substances into their gizzard, to re- 



