EDIBLE SNAIL, 113 



Connection between nephridium and pericardium in Helix. O. Ntisslin, Beitrage 



zur Anat. und Physiol. der Pulmonaten, Tubingen, 1879. Cf. Haller, Marine 

 Rhipidoglossa, M. J. xi. 1886. 



22. EDIBLE SNAIL (Helix pomatia), 



Dissected so as to show its digestive and reproductive, together with portions of its 

 circulatory and respiratory organs. 



THE body has been detached from the shell, and the greater part of 

 the mantle and skin has been removed. The coils of the right lobe of the 

 liver (hepato-pancreas), which occupy the upper whorls of the shell and 

 lodge the hermaphrodite gland, are arranged with the rest of the reproduc- 

 tive organs on the right hand : the left lobe of the liver, intestine, heart and 

 respiratory chamber lie to the left : the nerve-collar, buccal mass and 

 stomach occupy the centre. Between the latter and the parts to the left 

 lies at a lower level the sole-shaped ' foot ' upon which the animal creeps. 

 A black bristle has been passed between the cerebral or supra-oesophageal 

 ganglia and the buccal mass which contains the crescent-shaped chitinoid 

 jaw and the lingual ribbon or radula, structures invisible here. The buccal 

 mass is somewhat retracted, as it is when the snail ' draws in his head.' On 

 the left side of the buccal mass may be seen the sheath which contains the 

 connectives from the cerebral to the infra-oesophageal ganglia, a small 

 portion of which with numerous nerves proceeding from it is also visible. 

 From the base of the buccal mass projects the small conical ' sac ' of the 

 radula below, while the oesophagus and ducts of the salivary glands enter it 

 above, the oesophagus between the two salivary ducts. The oesophagus 

 expands into the stomach which is embraced by the salivary glands. The 

 right and left bile ducts, from the right and left lobes of the liver respectively, 

 enter one on either side the pylorus, and at this spot there is a small 

 projecting median caecum. Just below the heart, which has been exposed 

 in the pericardium, and above the aorta cephalica, which has been cut 

 transversely, the intestine passes on to the convex surface of the left lobe of 

 the liver. It reappears on the left side of this lobe in the preparation, on the 

 right side in the natural position of the parts in the living animal, and 

 passes straight to the anus. A white bristle has been placed in the anus 

 through the pulmonary aperture. To the right side of the terminal segment 

 of the intestine is seen the wall of the pulmonary chamber with its network 

 of vessels. 



The hermaphrodite gland or ovo-testis is lodged in the concavity of 

 the penultimate and ante-penultimate coils of the right lobe of the liver, 

 which occupy the lowest portion of this preparation on the right hand. 

 From the gland a convoluted hermaphrodite duct passes up to a spleen- 



I 



