INTESTINES OF BIRDS. 169 



position of the intestinal canal : after the usual long and narrow 

 duodenal fold, the ileum ^ makes a fold which is mdened at the end ; 

 it then forms a close fold upon itself, at the termination of which 

 the rectum commences. In the MaccaAv the course of the small 

 intestine is somewhat peculiar : after forming the duodenal fold, 

 it is disposed in three distinct packets of folds : the intestine, 

 after forming the first two, passes alternately from one to the 

 other, describing shorter folds upon each ; it then forms the third 

 distinct fold, which is a long one, at the termination of which the 

 ileum adheres closely to the right side of the gizzard, and then 

 passes backward and dilates into the rectum. 



In the Rasores the Dove-tribe have the small intestines dis- 

 posed in three principal folds ; the first is the duodenal fold, fig. 

 85,/,/; the second is a long and narrow fold, coiled and doubled 

 upon itself, with the turns closely connected together, ib. k ; the 

 third is also a long fold, which is bent or twisted, ib. k'. In the 

 Common Fowl the duodenum is disposed in a long simple loop ; 

 the ileum passes toward the left, and is disposed in loose folds on 

 the right and lower edge of the mesentery ; the ileum before its 

 termination passes up behind the preceding folds, and is accom- 

 panied as far as the root of the mesentery by the two coeca, which 

 there open into the commencement of the large intestine. 



The Ostrich presents the most complicated course of the in- 

 testinal canal in the whole class of Birds. The duodenal fold is 

 about a foot in length, and the returning part makes a bend upon 

 itself before it reaches the pylorus ; the intestine then turns down 

 again behind the duodenal folds and gradually acquires a wider 

 mesentery. The ileum after a few folds ascends toward the left 

 side, accompanied by the two long coeca, and becomes again con- 

 nected with the posterior part of the duodenal mesentery ; beyond 

 which the co^ca enter the intestine behind the root of the me- 

 sentery, and the large intestine commences. This part differs 

 from the rectum in other Birds in its great extent, being nearly 

 double the length of the small intestines, and being disposed in 

 folds upon a wide mesentery. It terminates by an oblique val- 

 vular aperture in a large urinary receptacle. In the Bustard the 

 rectum is a foot in length, which is the nearest approach to the 

 Ostrich which the rest of the class make in this respect. 



The small intestines in the Grallatores are characterised by 

 their small diameter and long and narrow folds ; these are some- 

 times extended parallel to one another, as in the Crane and Coot ; 



' There is seldom any part of the small intestine empty so us to merit the name of 

 jejunum. 



