VISCERAL HUMP 107 



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 between 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. 



h. The hermaphrodite gland is a small yellowish body 

 on the inner side of the upper half of the second 

 turn of the spiral. 



i. The columellar muscle, by which the animal can be 

 retracted within the shell, runs along the right 

 or inner side of the spiral, and is attached to the 

 columella in the upper half of the first turn. 



II. DISSECTION OF THE MANTLE-CAVITY AND OKGANS 

 IN KELATION WITH IT. 



The respiratory or mantle-cavity of the snail lies along 

 the dorsal surface, commencing at the collar, and extending 

 backwards rather more than three-fourths of the way round 

 the first turn ^f the spiral. It is formed by a transverse fold 

 of skin which, arising from the dorsal surface of the visceral 



