DIGESTIVE SYSTEM. 101 



serves as a bag for carrying food. It may be compared to the cheek 

 pouches of the Rodentia. A very singular peculiarity occurs in Pala- 

 medea cornuta, which consists in the presence of a craw-like dilata- 

 tion between the provenlriculus and gizzard. 



At the extremity of the gullet there is found very generally occur- 

 ring throughout the class of Birds a first division of the stomach, 

 called the proventriculus or bulbus glandulosus y the walls of which, as 

 the latter name implies, are thickly studded with a layer of simple or 

 divided glandular follicles, that pour out their secretion by separate 

 mouths upon the internal surface of the stomach. The proventricu- 

 lus is in general, e. g. in the GallinaB, Geese, and Ducks of a smaller 

 size than their very largely-developed gizzard, but frequently the re- 

 verse is the case to a striking degree, as in the genus Thalassodroma 

 or Storm-petrel, and the Puffin. In the Pigeons long slender strips 

 of glands are sent upward from the proventriculus over the oesopha- 

 gus as far as the crop, and between these the oesophagus is thin and 

 membranous. More rarely, as in the Northern Divers, the com- 

 mencement of the proventriculus is indicated by a narrow chaplet of 

 glandular follicles situated at the termination of the gullet, or it is 

 not recognisable externally by any expansion, as in Euphone vio- 

 lacea ; its cavity, however, is provided throughout its entire extent 

 with follicles. The gastric follicles are usually simple coeca of very 

 small size, as in the carnivorous Birds, and frequently also in the 

 granivorous Birds, as the Peacock and Cassowary, but they are lar- 

 ger and divided at the extremity in the Common Fowl, or even 

 slightly racemoid, as in the Ostrich. The proventriculus is dis- 

 tinctly separated by a constriction from the gizzard in all cases 

 where the latter is very fleshy, but when it is more membranous, 

 both stomachs communicate with each other by a wide aperture. 



The second fleshy muscular stomach or Gizzard is very highly 

 developed in the Granivorous birds, as in the Fowls and Pigeons, 

 and also in many Grallae and Palmipedes, as the Swan, Goose, Duck, 

 Coot, and Flamingo. The thick muscular layers upon either side 

 are here divided in the middle by a tendinous disc, into two 

 halves. The cavity of the gizzard is of but small extent, owing to 

 the projection internally of its strong muscular parietes, and is in- 

 vested by a hard, pergamentaceous or even horny epithelium, which 

 can be readily detached. Occasionally corneous tubercles project 

 from the epithelium, as in the Puffin. The gizzard is frequently also 

 of very small size, not very muscular, and provided only with a flat 

 thin disc of radiating tendinous fibres. In the Pelican and Gannet 



