440 



AVES. 



first loof) ot the small intestine (corresponding to tlie duodenum) 

 surrounds the elongated pancreas, the ducts of which (one to 

 three in number), as well as the usually double bile ducts, open 

 in this region. A gall-bladder is usually present. The begin- 

 ning of the short large intestine is marked by a circular valve, 



and by the origin of two caeca ; 

 it presents no distinction into 

 colon and rectum, and passes 

 into the cloaca, into which the 

 urinogenital apparatus also 

 opens. At its entrance into 

 the cloaca it presents a 

 sphincter-like circular fold. 

 A peculiar glandular sac — the 

 bursa Fabricii — opens into the 

 dorsal wall of the cloaca. 

 There is no bladder in the adult. 

 The falciform ligament has 

 a considerable extension, pass- 

 ing back from the pericardium 

 to the hinder part of the body 

 cavity as a median septum. 

 The large omentum is well 

 developed. 



The cloaca usually presents 

 three fairly well-marked divi- 

 sions separated by folds. The 

 anterior of these, often called 

 the coprodaeum, is the dilated 

 hind end of the rectum ; its 

 lining is however different from 

 that of the rectum from which 

 it is often separated by the 

 fold above referred to. The 

 middle chamber is called 

 the urodaeum ; it is smaller than the others and receives 

 the openings of the urinogenital ducts. The posterior chamber 

 which opens by the vent, may be termed the vestibule (some- 

 times erroneously called proctodaeum) ; it receives the bursa 

 Fabricii dorsallv. Most birds are without an organ of copula- 



FlG. 243. — Digestive canal of a bird Ad 

 large intestine (rectum) ; C tlie two 

 rectal caeca ; D small intestine ; Dm 

 proventriculus ; H liver ; K crop ; Kl 

 cloaca ; Km gizzard ; Oe oesophagus ; 

 Ov oviduct : P pancreas placed in the 

 duodenal loop ; U ureter. 



