434 MANUAL OF ZOOLOGY. 



but in some cases as in the Parrots it is soft and fleshy, and 

 then, doubtless, is to some extent connected with the sense of 

 taste. It is essentially composed of a prolongation of the 

 hyoid bone (the glosso-hyal), which is sheathed in horn, and is 

 variously serrated or fringed. 



Salivary glands are invariably present, but they are rarely 

 of large size, and they have often a very simple structure. 



In accordance with the structure of the neck, the gullet in 

 birds is usually of great length, and it is generally very dilatable. 

 In the carnivorous, or Raptorial, and in the granivorous birds, 

 the gullet (fig. 171, o) is dilated into a pouch, which is situated 



Fig. 171. Digestive System of the Common Fowl (after Owen), o Gullet ; c Crop ; 

 / Proventriculus ; g Gizzard ; sm Small intestine ; k Intestinal cseca ; / Large in- 

 testine; cl Cloaca. 



at the lower part of the neck, just in front of the merry-thought. 

 This is what is known as the " crop " or " ingluvies " (c), and 

 it may be either a mere dilatation of the tube of the gullet, or 

 it may be a single or double pouch. The food is detained in 

 the crop for a longer or shorter time, according to its nature, 

 before it is subjected to the action of the proper digestive 

 organs. The oesophagus, after leaving the crop, shortly opens 

 into a second cavity, which is known as the " proventriculus " 

 or " ventriculus succenturiatus " (/). This is the true digestive 

 cavity, and its mucous membrane is richly supplied with gastric 



