138 



THE SNAIL. 



large pedal artery which runs back along the foot ; 

 and finally divides into large branches supplying the 

 tentacles and buccal mass. 



The venous system. 



The venous system consists partly of tubular 

 vessels with definite walls, and partly of irregular 

 lacunar spaces, the exact relations of which to the 

 arteries and to the body-cavity are not determined. 



Fiu. 33. Helix pomatia. Section taken along the axis of the shell, and 

 transversely to the foot. The shell is represented by the thick 

 black line. (a. m. m.) 



A, umbilicus. AG, albumen gland. B, nucleus of shell. C, crop. D, 

 common duct. E, flagellum. F, foot. G, pulmonary sinus. HG, hermaphro- 

 dite gland. |, intestine. K, kidney. LL, left lobe of liver. MC, mantle- 

 cavity or lung. MG, mucous glands. P, pedal gland. PC, pericardial cavity. 

 PS, pedal sinu3. pv, pulmonary vessels. R, rectum. R|_, right lobe of 

 liver, rm, retractor muscles, s, spermotheca. SG, salivary gland. U, 

 ureter, v, ventricle. 



