HINTS TO COLLECTORS. 95 



the opercula which close the apertures of their shells. 

 Each one should be detached from the foot of the snail, 

 the interior of the shell plugged with cotton wool, and 

 the specimen gummed down in its natural position. 



The shells of mussels and other bivalves which 

 gape a great deal after the animal has been removed, 

 should be carefully closed and bound with thread 

 until dry. Bivalves as small as Sphoeriuiin corneum 

 may be treated in this way, but the smaller species 

 of Pisidium and some of the smaller univalves, as, 

 for instance, the little Sedge-shell Carychium mini- 

 mum, may be dried in hot sand. Care, however, is 

 required in the process, since too much heat will cause 

 a transfusion of the carbonaceous matter of the animal 

 into the substance of the shell, and so discolour it. 



Slugs require a different treatment. On this sub- 

 ject, Mr. Tate, in his " British Land and Freshwater 

 Mollusca," says: "As regards the internal shell, 

 it may be obtained by making a conical incision in 

 the shield, taking care not to cut down upon the 

 calcareous plate, which can then be removed without 

 difficulty. The animals can only be conserved by 

 keeping them in some preservative fluid ; but the 

 great object to keep in view is to have the slug 



