Edible Snail. 49 



posterior border of the buccal mass, we see mesially the entrance 

 into it of the oesophagus ; and on either side that of the duct 

 of either salivary gland, just above the stomatogastrie ganglion. 

 Posteriorly to this, the oesophagus expands gradually into the 

 stomach, which is embraced by \he salivary glands, and has a 

 pyloric caecum developed upon it, just where it comes into relation 

 with the liver. The bile-duct, which is single at its termination, 

 opens at the pylorus, as directly into the intestine as into the 

 stomach. The first segment of the intestine runs up towards the 

 heart, and, together with the oesophagus and stomach, makes up 

 a cm-ve with its concavity towards the pedal ganglion ; as is the 

 case also in Cephalopoda, Pteropoda, and Lamellibranehiatap. Just 

 below the heart, and above the aorta, which is seen to be cut 

 across, the intestine passes on to the external surface of the liver, 

 to reappear again on the left of the preparation, whence it runs 

 with a straight course to the anus, into which a white bristle has 

 been introduced. To the right of the terminal segment of the 

 intestine we see the pulmonary sac, its vessels, and the heart; 

 and between these structures and the buccal mass, the left parietal 

 nerve passes off to distribute itself in two divisions to the body 

 walls. At a little lower level, and a little posteriorly, a more 

 delicate nerve distributes itself to the muscular fibres, which retract 

 the posterior part of the foot, joining them just as they rise above 

 the level of the mass of the foot, to pass up to their insertion on 

 the columella. This portion of the columellar muscles lies, in this 

 preparation, immediately to the left of the buccal mass. It is 

 much feebler than the anterior retractor columellar muscles, as 

 may be seen from the fact that much of the posterior part of the 

 animal's foot is still left unprotected, when during life it has 

 retracted itself as far as usual into the shell. The posterior 

 retractor fibres are continuous on either side with the general 

 muscular envelope of the viscera, and a deep furrow separates 

 them, as in life, from a portion of the mantle which is here left 

 in situ. Immediately above these structures we see three nerves, 

 which have been cut away from their peripheral distribution, but 

 remain attached to the centre whence they arise, viz. the upper 



r See Huxley, Eoyal Society's Transactions, 1853, pp. 46, 57 ; English Cyclopaedia, 

 Article 'Molluaca,' p. 858; but see also page 68, infra. 

 E! 



