122 THE SNAIL. 



is sufficiently transparent to allow the several organs 

 to be seen through it. 



For convenience of description the basal or 

 largest turn of the spiral, commencing with the 

 collar, will be spoken of as the first turn, the next 

 as the second, and so on. 



Place the snail in a dissecting dish under water, and 

 determine the positions of the organs mentioned below. Note 

 that the outer side of the spiral corresponds to the animal's left 

 side, and the inner side to the animal's right. 



a. The kidney is a large, somewhat triangular body, 



of a yellowish- white colour and granular appear- 

 ance, lying about halfway round the first turn of 

 the spiral, opposite to the collar. 



b. The pericardium, enclosing the heart, is an oval 



sac, lying immediately to the left of the anterior 

 half of the kidney, which is notched to receive it. 



c. The mantle, forming the thin roof of the respiratory 



cavity, extends forwards along the dorsal surface 

 and left side of the body, from the pericardium 

 and kidney to the collar. 



d. The liver is a dark reddish-brown mass, which 



begins immediately beyond the pericardium and 

 kidney, and extends to the top of the spiral. 



e. The intestine is a thin-walled tube, much paler in 



colour than the liver, and appearing on the 

 surface at one or two places in the first and 

 second turns of the spiral. 



f. The rectum runs along the right border of the first 



half-turn of the spiral, just below the ridge-like 

 thickening which borders the right or inner side 

 of the spiral. 



g. The albumen gland is a large white or yellowish 



mass at the junction of the first and second 

 turns of the spiral. It separates the right and 

 left lobes of the liver from each other. 



