ALIMENTARY CANAL 



29 



' short-circuiting ' connection, as MITCHELL terms it, 

 between the duodenal and the main mesenteric stem. 



Fi(i. 13. Haliadus albicilla ; IXTSETINAL TRACT. 

 x as in fig. 12. (After CHALMERS MITCHELL.) 



FIG. 14. Am uniniium ; I.\TI:STINAL TKACT. 

 ., as in fig. 12. (After CHAI.MKKS .M m 11 KLL.) 



In other groups of birds this simple state of affairs is further 

 evolved, but in some there are remains of the primitive 



