Hillside. 145 



shells, apparently those of one of the common snails, Helix 

 nemoralis. The name Helix, or " spiral," is a very happy 

 one to apply to the snail, is it not? The shells are not at all 

 rare here ; but it wants a really heavy shower to bring out 

 these creatures in full force, and thus to enable us to get a 

 correct idea of the great variation to which their shells 



" Deftly wrought by Hand invisible, 



Painted and sculptured by th' unseen Power which works 

 In all things living, and fashions out their shapes. 

 The calcine atoms, drawn by that mysterious force 

 Through which th' Almighty works, each to its proper place, 

 Builds up by slow degrees the shell whose shape 

 And beauty we admire " 



are subject. Examine one of these shells ! Notice how 

 layer upon layer has been built beyond its predecessor, as its 

 inmate has grown larger and larger, and found its home 

 getting too small for its comfort. 



How is the shell made larger ? Look at one carefully ! 

 This one draws its head back into its own substance as it 

 were. The outside flesh nearest the shell is called the 

 " mantle," and this has the power of secreting carbonate of 

 lime. As the animal grows larger and the mantle stretches 

 slightly beyond the shell, a layer of carbonate of lime and 

 membranous matter is secreted beyond the last ring of the 

 shell, and as the size of the animal increases, the shell is 

 built to meet its wants, each layer extending beyond its 

 predecessor. This goes on until the snail has attained its 

 largest size. Here is a shell which will illustrate the 

 matter. A membranous hood extends beyond the edge of 

 the hard shell. This is the basement, which will become 

 harder and harder by successive deposits of carbonate of 

 lime until it becomes similar to the rest of the shell. The 



L 



