122 Proceedings of the Royal Society of Victoria. 



Its wall is thrown into deep longitudinal folds, and the lumen 

 is capable of being closed. 



At the anterior limit its wall foi'ms a decided radial fold, 

 projecting inwards as a ridge, after which it joins with the caical 

 organs (Fig. 9). 



As this junction is approached the cellular wall is free from 

 muscles, and gradually widens like a funnel, and within this 

 widened space the ends of the oesophageal valve lie. 



The cuticle covers the cells from the commencement, and 

 almost immediately is beset with short setas, which point pos- 

 teriorly, and continue as far as the mid-terminal canal. 



At the posterior extremity, the strong bands of annular muscles 

 cease, and the wall suddenly dilates to a width of about 1'5 

 mm., which marks the commencement of the mid-terminal canal. 

 At the opening, loose folds of the wall of the fore-terminal 

 canal project into the mid-terminal canal for a short distance, 

 which act as valves to prevent a retrograde movement of tlie 

 food material. 



The Arborescent Org-ans of Dufour. 



These are four very small bunches of minute dichotomously 

 branching colourless tubes, forming a dorsal and ventral pair. 

 An efferent duct from each bunch opens into the fore-terminal 

 canal, on the anterior ridge just mentioned. 



Cuenot has satisfied himself that they do not play any part 

 in intestinal absorption, nor secrete any digestive fluid. He 

 considers them to be excretory organs, eliminating a product 

 made, doubtless, in a very small quantity. I venture to suggest 

 that the product may be of use for the purpose of neutralizing 

 the acid digested food residue from the ca^ca. 



The Mid-terminal Canal. 



This which is the " chylific stomach," ventriculus or mid- 

 intestine of other authors measures 13-15 mm. in length, and 

 its width at the commencement, when distended by food, is 1'5 

 mm., but it becomes gradually narrower as it unites with the 

 hind-terminal canal. In its course it describes a full round 

 turn in the body-cavity. 



