294 PROCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



Alimentary Canal. The mouth appears as an apparently transverse 

 slit at the free end of the proboscis or introvert. 



On slitting open the proboscis (Fig. 2, Ph.') the buccal mass is revealed, 

 and on making a longitudinal slit in this the mouth is seen to be 

 provided with two hardened plates, an upper and a lower, of a brilliant 

 orange colour, the margins being deep reddish purple. At the corners 

 of the mouth are two small horseshoe-shaped areas tinged with purple, 

 their use not being quite apparent to me, unless they act as gussets 

 and allow the lips to open or foi-m a disc or sucker, and so give 

 the animal a firmer hold of its prey, and having drilled the shell, suck 

 the contents to within reach of the radula. 



Behind the hardened plates is the odontophore, bearing the radula, 

 which is rather short, and distinctly visible on account of its bright 

 purple colour. 



The hiccal chamber is elongated (Fig. 5, A and D, Oe.) and 

 apparently extends the whole length of the introvert, and the 

 hinder part is much sacculated internally. On leaving the buccal 

 chamber the oesophagus is not folded on itself, but is constricted and 

 dips downward, and here the nerve-collar is placed. The constriction 

 continues for a short distance, when it suddenly enlarges, forming the 

 crop (Figs. 1 and 5, Oe'.). This enlargement only aifects the line of 

 the upper portion of the tube, and is different in texture from the 

 lower portion, its surface showing a cross hatching of fine muscular 

 fibres. The crop continues, though slowly decreasing in size, till it 

 passes underneath the division-wall at the far end of the pallial 

 chamber, at which point it rather suddenly decreases and becomes the 

 true oesophagus. The crop has a complicated internal structure, being 

 provided from end to end with a number of transverse lamellae 

 pigmented with brown (Fig. 5, B, C, and D, Oe'.). They are cut 

 through in the drawing and laid back. They spring from and are 

 connected to a longitudinal fold shown to the left in the above figure. 

 They may be secretory organs, as they have a spongy glandular 

 appearance and give a distinctly alkaline reaction with red litmus, 

 but I could get no reaction on testing for glycogen. This may have 

 been destroyed by their long immersion in formaldehyde. Two raised 

 folds run the length of the crop, and these, as far as I could make 

 out, are not tubes. The one to the right is very distinct and much 

 folded longitudinally, the one to the left being much less distinct. 

 In life they may form a guide for the masticated food and also prevent 

 its coming into actual contact with the lamellae, though open to the 

 action of their secretion, if any. On leaving the neighbourhood of 

 the pallial chamber the walls of the oesophagus get much thinner, 

 and it slowly enlarges till the stomach is reached. This organ is 

 embedded in the liver and its walls are practically transparent, the 

 openings of the hepatic ducts being distinctly visible. 



The stomach is situated in the bight of the U described by the single 

 turn of the alimentary canal, and is not easily sepai'ated from the 

 small intestine, the size decreasing gradually. The intestine on 

 leaving the stomach turns to the right, penetrating the kidney sac and 

 traversing the nephridium. At its junction with the large intestine 



