CIVIC PROBLEMS RELATING TO MOLLUSKS 283 



The edible snail (Helix pomatia) is imported from Europe and is 

 raised in specially fenced gardens and fattened for market. This may 



FIG. 130. A common land snail 



be studied as an interesting novelty in most American communities. 

 For all we know, may not our big, fat garden slugs be food delicacies ? 



Compare garden slugs with marine or fresh-water snails, which they 

 may be seen to resemble, except in respect 

 to the rudimentary shell. These slugs are 

 often as destructive in gardens as any in- 

 sect, and, being nocturnal, are little known. 

 Collect the eggs (translucent, yellowish, 

 about the size of buckshot, in masses of 

 thirty or more, found in damp places under 

 boards) and keep them in a glass jar or 

 aquarium to watch their development. If 

 the life history of these pests were better 

 known, we might control them more effec- 

 tively about our gardens and greenhouses. 



In connection with other field work, 

 make a collection of common marine, 

 fresh-water, and terrestrial gastropods. 

 Keep them in suitable aquaria or vivaria, 

 to study habits and foods. Note that some 

 snails are " left-handed " and most are 

 " right-handed." (If held with opening up 

 and spire pointing away from you, the 



dextral shells have the opening to the right, the sinistral, to the left.) 

 The commonest and most interesting are the pond snails, belonging 

 to the genus Physa, which can be-readily distinguished by their sinistral 



FIG. 131. Common snails, 

 sinistral and dextral 



