HANDBOOK OF SHELLS. 41 



us, one nervous centre, but three, and are far more tenacious of 

 life ; hence, unless all the nerves are destroyed at once, a great 

 deal of suffering is entailed on the poor creature ; and if merely 

 crushed under foot, the mangled portions "will live for hours. 

 Hot water has also the advantage of tending to remove the dirt 

 which is almost sure to have gathered on the shells, and so 

 helping to prepare them better for the cabinet. As soon as the 

 water is cool enough, fish out the shells one by one and proceed 

 to extract the dead animals. This, if the mollusk is univalve 

 (i.e., whose shell is composed of a single piece), such as an 

 ordinary garden snail, can easily be done by picking them out 

 with a pin ; you will find, probably, that some of the smaller 

 ones have shrunk back so far into their shells as to be beyond the 

 reach of a straight, pin, so it will be necessary to bend the pin 

 with a pair of pliers, or, if none are at hand, a key will answer 

 the purpose if the pin be put into one of the notches and bent 

 over the edge until sufficiently curved to reach up the shell. You 

 will find it convenient to keep a set of pins bent to different 

 curves, to which you may fit handles by cutting off the heads and 

 sticking them into match stems. It is a good plan to soak some 

 of the smaller snails in clean cold water before killing them, as 

 they swell out -with the water, and do not, when dead, retreat so far 

 into their shells. If you have a microscope, and wish to keep the 

 animals till you have time to get the tongues out, drop the bodies 

 into small bottles of methylated spirit and water, when they will 

 keep till required, otherwise they should of course be thrown 

 away at once. The now empty shells should be washed in clean 

 warm water, and, if very dirty, gently scrubbed with a soft nail or 

 tooth brush, and then carefully dried. 



In such shells as the Periwinkle, Whelk, etc., whose inhabit- 

 ants close the entrance of their dwelling with a trap-door, or 

 operculum as it is called, you should be careful to preserve each 

 with its proper shell. 



If you are cleaning bivalves, or shells composed of two pieces, 

 like the common mussel, you will have to remove the animal with 

 a penknife, and while leaving the inside quite clean, be very 

 careful not to break the ligament which serves as a hinge ; then 

 wash as before, and tie them together to prevent their gaping 

 open when dry. 



Sometimes the fresh-water or marine shells are so coated over 

 with a vegetable growth that no scrubbing with water alone will 

 remove it, and in these cases a weak solution of caustic soda may 

 be used, but very carefully, since, if too strong a solution be em- 

 ployed, the surface of the shell will be removed with the dirt, and 



