168 



ANATOI^IY OF VERTEBRATES. 



The duodenum forms a long and broad fold, the lower part of 

 which is commonly bent or doubled upon itself; the intestine 

 then passes baclvAvard on the right side of the abdomen, crosses to 

 the left, and is disposed in deep folds upon the edge of a scolloped 



Abdominal viscera of a Pigeon, xxxiv. 



mesentery; towards its termination the ileum passes up behind 

 the stomach and adheres to it, having here but a narrow mesen- 

 tery ; then passing down the posterior part of the abdomen the 

 ileum makes another loose fold and ends in the rectum, which is 

 continued straio-ht to the cloaca.' In the Owls, the last fold of 

 the ileum is nearly as long as the duodenal fold, and the coeca 

 adhere to each side of the fold. 



In the Diurnal Raptores the intestinal canal is only twice the 

 length of the body, except in the fish-eating Osprey, in which the 

 intestines are very narrow, and are to the length of the Bird itself 

 as eight to one. 



In the Cantores the scolloped folds of the small intestine are 

 narrower and longer than in the Raptores, and the ileum gene- 

 rally adheres to the duodenal mesentery and pancreas instead of 

 to the stomach, prior to passing down to form its last fold and to 

 terminate in the rectum. In the Raven the small intestines are 

 disposed at their commencement in concentric folds. 



Among the Scansores the Cuckoo presents the following dis- 



' In fig. 78, tlic intestines are not represented according to their natural arrange- 

 ment. 



