114 THE SNAIL 



1. The buccal mass or pharynx is the dilated anterior end 



of the canal, into which the mouth opens. It forms 

 a prominent rounded mass in the head, with stout 

 muscular walls, and will be more folly examined 

 at a later stage of the dissection. It contains th6 

 odoutophore (p. 121). 



Insert a seeker into the mouth, and note that it passes 

 upwards and backwards into the buccal mass. 



2. The oesopliagus is a narrow thin-waUed tube, which 



arises from the dorsal surface of the buccal mass 

 and runs backwards, passing into the crop. 



3. 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 ' stomacli ' is a slightly dilated loop of the ahmentary 



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. 



5. The intestine describes a somewhat S-shaped course, 



and is imbedded in the Uver, 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 right lobe of the 

 liver, to the right side 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 



