656 DR. p. CHALMERS MITCHELL ON THE 



note dijBerences in the odour on the dissecting table. In the case 

 especially of vegetarian and omnivorous creatures where the 

 digestive tract is bulky, and large quantities of food are taken, 

 there is usually a very offensive odour, showing that putrefaction 

 attends the processes of intestinal digestion. In other cases, and 

 amongst birds, notably in birds-of-prey and many fish-eaters like 

 the Divers, the odour of the alimentary tract behind the stomach 

 is rarely offensive, and, sometimes, even attractive and aromatic. 

 Although I was unable to examine this specimen of the Shoe- 

 bill until it had been dead for several days, the contents of the 

 intestinal tract were not offensive. 



In the figure (text-fig. 122) I represent the course of the ali- 

 mentary canal, from the stomach to the cloaca, dissected out in a 

 fashion which, as I have described in former memoii'S (26, 30), 

 seems to me to give much information as to its morphology and to 

 afibrd a useful basis of comparison with the conditions existing in 

 the different grouj)s of birds. The secondar}^ foldings and modes 

 in which the gut is packed in the body-cavity are naturally not 

 shown by this method, but the relation of the gut to the primitive 

 mesentery, the portions of it which have been expanded into 

 loops, and the configuration of these loops, appear with diagram- 

 matic clearness. The first specialized loop is the duodenum ; it 

 is relatively not quite so long as in Herons generally, but it shows 

 on its distal limb a minor expansion, represented in the drawing 

 as two short folds, and comparable with the condition which I 

 have figured in Nycticorax and Ardea. Then follows a second 

 definite loop with a minor loop on its proximal limb, then a well 

 marked loop, and then a few irregular twists, after which comes 

 the portion bearing the remnant of Meckel's diverticulum (text- 

 fig. 122, m.), the vestige of the yolk-sac, lying in the line of axis of 

 the main branch of the portal vein. In Balceniceps this was very 

 slender, and bound closely to the inferior edge of the gut b}^ a 

 ventral mesentery. It might quite easily have been overlooked, if 

 it had been sought for in the usual fashion, merely by running 

 the gut through the fingers, but when the tract was laid out in 

 the way I recommend, so that the blood-vessels were visible and 

 the mesentery undisturbed, it was at once obvious. The part of 

 Meckel's tract between this diverticulum and the usual position 

 of the caeca is thrown first into a series of short ill-defined loops 

 and then into a long and definite supra-duodenal loop (text- 

 fig. 122, S.D.F.) closely attached to the duodenum in the un- 

 disturbed condition and supplied from the duodenal vein by what 

 I have termed a "bridging" or short-circuiting vessel, which 

 traverses the mesentery and must be cut through in pi^ocess of 

 laying out the gut (text-fig. 122 x, x). Then follows a rather 

 irregular piece of gut forming two of the folds which I have 

 described as " supra-csecal " kinks, the presence of at least one 

 of these being characteristic of the great assemblage of birds 

 containing the eagles and vultures, herons and storks, penguins 

 and petrels. 



