INTESTINAL TEACT OF BIRDS. 



195 



(1) ScopiD^. — In Scojms umbretta (fig. 16) the duodonura is long and slightly twisted. 

 Meckel's tract is nearly symmetrical, a large Meckel's diverticulum being near the centre 

 of its periphery, and is expcinded into a number of wide, irregular, but in the main straight 

 minor loops, the last of these being longer and forming a typical supra-duodenal loop. 

 The rectum is straight, of moderate length, and the pair of caeca are reduced. The veins 

 are typical. A small area supplied by the rectal vein corresponds to the supra-caecal 

 kink. 



Fi-. 16. 



Intestinal Tract of Scopus umhrettii. Lettering as before. 



(2) Ardeid/E. — In the Herons and Bitterns, of which I have examined a number of 

 species, the ground-form is like that in Scopus. The duodenum is a long narrow loop, 

 nearly always considerably twisted to the left, usually more so than appears in tlie two 

 figures {Nycticorax grisem, fig. 17, and Ardeu candklissima, fig. 18). Meckel's tract 

 may be rather elongated as in Nycticorax, or relatively shorter as in Ardea. It is 

 always drawn out into a large number of minor loops, many of which are irregularly 

 folded, and not infrequently complex in themselves ; the distal minor loops in Ardea 

 (fig. 18) show this in a relatively simple form. In the Little Bittern and some other 



