BULLETIN 39, UNITED STATES NATIONAL MUSEUM. [38] 



hol, diluted with a proper proportiou of water. If the specimens are 

 large they should first be put into a jar kept for that special purpose, 

 iu which the alcohol is comparatively weak, having, say, 50 ])er cent of 

 water added to it. After the immersion of specimens in this jar for 

 several days the fluids will have been extracted by the alcohol, and a 

 specimen can then be removed, washed clean of mucus and dirt, which 

 will almost always be found about the aperture of a spiral shell, and 

 jjlaced in its own proper jar of 90 per cent alcohol diluted in the pro- 

 portion of about 30 per cent with jDure water. Siiecimeus to be pre- 

 pared for the cabinet require the removal of the soft j)arts if they are 

 still present, the cleaning oft' of parasitic or incmsting growths, and, in 

 the case of bivalves, securing the valves in a convenient ]30sition for 

 the cabinet. The different classes of shells may be treated of under 

 several heads. 



LAND AND FRESH-WATEE, SHELLS. 



Land and fresh- water shells are much more easy to deal with than 

 marine shells. In the case of spiral shells, such as Limncea, Planorhis, 

 Paludina, etc., the shell may first be washed clean of mud or comfer- 

 void growth, which may be conveniently done with the assistance of 

 an old tooth or nail brush. In the case of these forms the easiest way 

 to remove the soft parts is to place the shell for twenty-four hours in 

 weak alcohol, after which those i)arts can readily be removed ; but in 

 any case where the expense of alcohol is an object to be avoided, it will 

 be sufiflcient to place them in a small tin kettle, or other receptacle suit- 

 able for the purpose, and cover them with cold water; which should 

 then be slowly brought to the boiling point. As soon as it has reached 

 the boiling point it may be removed from the fire. The shells should 

 not be put into water already boiling, as it frequently cracks delicate 

 shells, and the sudden change of temperature injures their polish and 

 general appearance. 



For removing the soft parts from spiral shells the collector will 

 usually find a crooked pin sufflcient. For this purpose one of those 

 long steel pins used by ladies as hat pins is convenient. By heating 

 the pointed end in the flame of a candle or alcohol lamp the temper can 

 be taken out of the steel, so that it can be readily bent into any shape 

 desired. The proper form for reaching the retracted parts in a spiral 

 shell will of course be a spiral. With a small pair of plyers, different 

 forms can be experimented with, and those which are most satisfactory 

 decided upon. After the right form has been obtained, by heating the 

 pin again and plunging it suddenly into cold water the temper of the 

 steel will be measurably restored and the instrument ready for use. 

 Similar pins in their ordinary condition are convenient for cleaning out 

 sand or parasites from the recesses of sculptured shells, and for other 

 purposes. The attachment of a gastropod to its shell is at the central 

 axis or pillar of the shell, usually from half a turn to a turn and a 



