328 ZOOLOGY. 



liver are still in situ. The muscular stomach or gizzard 

 (St) of the main figure is represented very large, being 

 distended with food ; it is sometimes found much con- 

 tracted ; it is not sharply separated from the glandular 

 stomach, the two being in reality only the greatly modified 

 anterior and posterior divisions of the same dilatation. The 

 opening of the glandular stomach and the origin of the 

 small intestine are near together upon the anterior border 

 of the gizzard. The walls of this last organ are remarkable 

 for the enormous development of the muscular layers, 

 especially in the graminivorous birds, under which pigeons 

 are to be included ; the muscles radiate on each side from 

 a central tendinous space. The small intestine has nu- 

 merous coils, in the first of which lies the pancreas (Pan), 

 very much as in mammals. The large intestine (R) is rel 

 atively short ; its commencement is marked by two small 

 diverticula, distinctive of birds.* These appendages are 

 well developed in some species, as, for instance, the Galli- 

 nacece, while in the bustard they have been described as 

 three feet long. Gegenbaur considers the oesophagus, crop, 

 and stomach to be derived from the fore-gut, the small in- 

 testine from the mid-gut, and the large intestine from the 

 hind-gut of the embryo. The cloaca (Cl) is the short and 

 widened termination of the alimentary canal, and further 

 receives four ducts, the two ureters ( Ur), and in the male 

 the two vasa defer entia (Vd), in the fen ale the two ovi- 

 ducts. 



The digestive canal has two glandular appendages, the 

 pancreas (Pan) and the liver (Li) ; thei former, as in 

 birds generally, is quite large, whitish, and sends out a pro- 

 longation, which extends to the spleen ; it has two ducts. 

 The liver (Li) is very voluminous, dark reddish brown in 

 color, and forms two lobes, which rest upon the apex of the 

 heart and the gizzard, and conceal the glandular stomach. 

 There is no gall-bladder, a somewhat unusual feature among 

 birds, but there are two bile-ducts, the larger and shorter 



* Some snakes have a single diverticulum, as is said to be the case 

 witb herons. 



