i>4 STRUCTURE AND CLASSIFICATION OF BIRDS 



with the long axis of the body. On the other hand the 

 intestines of a gull, seen when the body wall is cut through 

 and without any other disturbance, have a watch spring -like 

 arrangement. In Platalea the coils are parallel, but mainly 

 at right angles to the long axis of the body. 



These and other variations have been mapped out by 

 GADOW into seven principal schemes, which are represented 



CL 



J 



d 



FIG. 7. INTESTINAL LOOPS (AFTER GADOW). 



a, isoccelous ; 6, auticoelous ; c, antiperiecelous ; rf, isoperiooelous ; e, cj'cloccelous : 

 /,</, plagioccelons ; /(, telogj'rous ; P, pylorus. 



]ST.B. The ascending branches are dotted. 



in the annexed cuts. These are, of course, not accurate 

 pictures of the actual course of the gut, but diagrams ' of the 

 principal relative positions ' of the intestinal loops ; and it 

 must be further explained, in relation to another mode of 

 mapping the intestine that we shall refer to immediately, 

 that the diagrams, mainly if not entirely, concern the lateral 

 foldings of the mesentery that have been already mentioned ; 

 they are representations, in fact, of the relations of the 

 folding of the gut to the body cavity and not to the medial 

 line of attachment of the mesentery ; nor is any attention 



