122 



THE SNAIL 



places ; the right pulmonary sinus is readily injected both 

 forwards and backwards, and the pedal sinuses may also be 

 injected. 



1. The arterial system. 



From the ventricle arises a single large vessel, 

 the aorta. This gives off almost at once a large 

 visceral artery, which runs along the outer surface 



PS p F 



FIG. 24. 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. 

 33, common duct. E, flagellum. F, foot. G-, sinus returning the blood to 

 the pulmonary chamber. HGr, hermaphrodite gland. I, intestine. K, kidney. 

 LL, left lobe of liver. MC, pulmonary or mantle cavity. MGr, mucous 

 glands. P, pedal gland. PC, pericardial cavity. PS, pedal sinus. 

 PV, pulmonary vessels. R, rectum. RL, right lobe of liver. RM, re- 

 tractor muscles. S, spermatheca. SG-, salivary gland. U, ureter. V, ven- 

 tricle. 



