INTESTINAL TEACT OF BIEDS. 



Fig. 20. 



199 



Intestinal Tract of Mycteria americana. 

 z, cut ends of veins from first loop of Meckel'a Tract to duodenal vein. 



(2) IBIDID.E. I have already figured the intestinal tract of Platalea leucorodia 

 (26. fig. 8). It is more archecentric than that found in other Ciconiiform birds. The 

 duodenum is a long narrow loop bent round to the left as in the Herons, but showing 

 no trace of spiral formation. Meckel's tract consists of an elongated system of short 

 loops, symmetrically disposed round the middle mesenteric vein, which runs from a 

 Meckel's diverticulum. This region of the gut is slightly twisted into a spiral in the 

 unfolded condition. The last loop of Meckel's tract forms a simple supra-duodenal fold ; 

 the caeca are short, and the rectum is straight but considerably reduced. Platalea is 

 certainly low down in the Ciconiiform scale, but none the less it displays the features of 

 the group in a simple form, and is quite different in the character of the gut from 

 Numenius (Plate 22), a low Charadriiform bird with which it has been compared, 



31* 



