IV.] THE COMMON SNAIL. 285 



b. Follow the crop forwards, it will be found to arise 

 from the roof of the thick-walled muscular buccal 

 mass, as a simple oesophageal tube. 



c. The sac of the radula, a small backwardly directed 



diverticulum of the floor of the buccal mass. 



d. The salivary glands, two irregular whitish masses 

 closely applied to the sides of the crop. They are 

 confluent postero-dorsally, and each is connected 

 with the roof of the mouth by an elongated 

 salivary duct. Follow one of these forwards, its 

 base becomes enlarged as it enters the mouth, at 

 the re-entering angle between the oesophagus and 

 buccal mass. 



e. Follow the crop backwards, it will be found to pass 

 into the visceral sac under cover of the right lobe 

 of the digestive gland (a yellowish brown mass, 

 filling the apical whorls of the visceral hump). 

 Turn this gland downwards and forwards, and 

 note, lying beneath it, the small sac-like stomach, 

 into the hinder end of which the oesophagus is seen 

 to pass. 



f. The digestive gland. Buried up in its small right 



lobe will be found the white ovotestis (remove this 

 with care). Its left lobe is much the larger of the 

 two; it is subdivided into three lobules which adapt 

 themselves to the coils of the intestine. Arising 

 from these are seen well-defined ducts; follow 

 them and note that they unite to form a single 

 short digestive duct. 



g. The stomach. Open this from the side, being 

 careful not to injure the right lobe of the digestive 

 gland, and wash out its contents. It is a simple 



