DIGESTIVE SYSTEM 115 



2. The oesophagus is a narrow thin- walled tube, which 

 arises from the dorsal surface of the buccal mass 

 and runs backwards, passing into the crop. 



5. The crop is a large fusiform thin-walled dilatation of 



the alimentary canal, lying partly in front of the 

 visceral hump, partly in the first turn of the spire. 

 It is widest about the middle of its length, and 

 gradually narrows behind. , 

 4. The ' stomach ' is a slightly dilated loop of the alimentary 

 canal, between the crop and the intestine. It lies 

 close to the surface of the visceral hump, near the 

 commencement of the second turn of the spire, and 

 between the right and left lobes of the liver. 

 Its mucous membrane is thrown into longitudinal 

 folds. 



6. The intestine describes a somewhat S'shaped course, 



and is embedded in the Hver, from which it is not 

 very easy to separate it. From the stomach it runs 

 back round the first turn of the spiral, lying in a 

 groove on the outer side of the left lobe of the 

 hver, to the hinder end of the mantle-cavity-, where 

 it passes into the rectum. It is superficial along a 

 great part of its course. 

 6. The rectum has already been traced along the right side 

 of the mantle-cavity to the anus. 



B. The Digestive Glands. 



1. The salivary glands are a pair of large white lobulated 

 glands lying on the upper surface and the sides of 

 the crop, to the walls of which they are attached by 



Fig. 30. — Helix pomatia. Dissection from the right side to show the 

 digestive and reproductive systems, (a. m. m.) 



A, anus. AG, albumen gland. B. buccal mass. O, sac of odontophore. 

 CG-. cerebral ganglion. D, jaw. S, mouth. F, flagellum. G, genital 

 aperture. H, crop. HD, hermaphrodite duct. HGj hermaphrodite gland. 

 1, intescine. K, dart sac. L, mucous glands. LD, left bile-duct. LIj,'left 

 lobes of liver. M, female portion of the common duct. IT, male portion of 

 the common duct. O, receptaculum seminis. O', dilated end of receptaculum 

 seminis. P, penis, retracted. PG, pedal ganglion. R, rectum. BD, right 

 bile-duct. B-L, right lobe of liver. S, ' stomach.' SD, salivary duct. SG, 

 salivary gland. T, tentacle. VD, vas deferens. "VG, viscero-pleural gan- 

 glion. Y, eye. Z, posterior end of foot. 



I 2 



