2 8 Charles GELDERD 



Yet, we think that we may certainly include in the région of the mid- 

 gut the following parts : the posterior portion of the pyloric chamber 

 behind the médian pièce 5, with the inferior latéral diverticula the cells 

 of which are in continuity with the cells of the digestive glands, the 

 digestive glands themselves, the dorsal diverticulum with a length of in- 

 testine of which we do not attempt to fix the limit. 



The dorsal diverticulum. 



The epithelium of the intestine where it joins the dorsal extremity of 

 the pyloric chamber is drawn into a sac forming the dorsal diverticulum, 

 FiG. 3, 11, dii>. 



In our type it is unpaired; in some species, however, a pair of such 

 sacs is found. 



In Macromysis Jlexuosa it is slightly rolled back on itself like the 

 finger of a glove. 



Its rounded off summit points backwards towards the intestine. 



In front, fig. 3-, of the diverticulum, a loose fold is seen which connects 

 the columnar epithelium of the intestin with the epithelial walls of the 

 stomach. 



Regarded in transverse section, fig. 19, the lumen of the diverticulum 

 is crescent shaped ; the latéral folds hang down like a hood at each side, 

 they seem separated on account of the obliquity of the section. 



The horizontal aspect of the sac with its overlapping folds is seen 

 in fig. 11. 



The overlapping folds open laterally into the lumen of the intestine a 

 little further back, fig. 12, 13, cf. fig. 30. 



A similar production is found in Gammarus described as the ^diverti- 

 cule supérieur t^, by Professor Ide. \n Gammarus, however, it is thrown 

 forwards and reposes on the vault of the cavity like the finger of a glove. 



From the nature of the epithelium, the author considers it to belong 

 to the midgut. 



Miss CussANS, also, places it in this région of the alimentary canal. 



The dorsal diverticulum differs very much in its form in the varions 

 species of Schizopoda that we hâve examined, and constitutes a distinctive 

 character in the détermination of the species. 



