38 Beautiful Shells. 



hollow; when the latter, the open end is called the 

 Umbilicus, meaning the navel or centre. The 

 opening at the bottom, from which the animal 

 issues, is the last portion finished, and this is called 

 the aperture, a Latin word adopted into the English 

 dictionary. Some of these Helices are wide and flat, 

 even hollow and cup-like, with the whorls rising 

 above the pillar — these are called discoid shells; 



DISCOID. TURBINATED. 



others which are long and narrow, with projecting 

 spires, are termed turbinated shells: the former 

 being more or less flat or disk-like, the latter 

 twisted, whirling, like a spinning-top, from the 

 Latin turbo — a whirling, a turning round. 



If we take a Common Snail, and plunge it into 

 boiling water, which will instantly kill it, so that 

 it can be removed from the shell, we shall find 

 the whole of that part of the body which was 

 lodged in the upper whorls, or spiral part of the 

 shell, is covered with a thin membrane or skin; 

 this is called the mantle, and that portion of it 



