122 



THE SNAIL 



places ; the right pulmona/ry siwus is readily injected both 

 forwa/rds and backwards, and the pedal sinuses may also be 

 injected. 



1. The aiterial system. 



From the ventricle arises a single large vessel, 

 the aorta. This gives off almost at once a large 

 visceral artery, which rims along the outer surface 



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. 

 D, common duct. E, flagellum. P, foot. Q-, sinus returning tlie blood to 

 tbe pulmonary clwmber. HG, bermaphrodite gland. I, intestine. K, kidney. 

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

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

 PV, pulmonary vessels. -R, rectum. B-L, right lobe of liver. BM, re- 

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

 tricle. 



