130 



THE SNAIL. 



2. 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. 



Two large irregular pedal sinuses lie in the foot, 

 one on each side of the pedal gland. 



A visceral sinus commences at the top of the 



Fig. 31. — 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 glaud. B nucleus of shell. C, crop. D, 

 common duct. E, flagellum. F, foot, G-, pulmonary sinus. HGr, hermapluro- 

 dite gland. I, intestine. K, kidney. LL, left lobe of liver. MO, mantle- 

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

 cavity. PS, pedal sinus. PV, pu'monary vessels. E, rectum. KL, right 

 lobe of liver. KM, retractor muscles. S, spermotlieca. SGr, salivary gland. 

 TJ, ureter. V, ventricle. 



