68 MOLLUSCA. 



Shells naturally arrange themselves under three distinct 

 heads ; Marine, Land, and Fluviatile, or Fresh Water. 



Marine Shells are only to be expected perfect, when pro 

 cured in a living state. The way to extract the animal, is to 

 pour some warm water on it ; but, if made too hot, it is liable 

 to crack the shells. When the animals are dead, they can 

 easily be pulled out with any hooked instrument, or fork, or, if 

 the animal is small, by a common pin. This applies to all 

 Marine Shells, whether Univalve, Bivalve, or Tubular. It is 

 of great consequence to preserve the ligament of Bivalve 

 Shells entire, so that the valves may not be separated. The 

 animals of Land and Fresh Water Shells are killed by the 

 same means, only that the water requires to be very hot. 



Unless the shells are covered with any extraneous matter, it 

 is not necessary to clean them. Marine Shells are, however, 

 very liable to be incrusted with other marine bodies, particularly 

 with Serpula and Balani, &c. These must be started off by means 

 of a sharp instrument : an engraving tool is well adapted for this 

 purpose. This must be done with great caution, in species 

 which have spines and other excrescences, as they are very 

 liable to be broken. Should any of the calcareous matter still 

 adhere, this must be removed, by applying to it a very weak 

 mixture of muriatic acid and water, applied with the point of a 

 quill, and then plunged into water, and allowed to remain till 

 the acid is quite extracted. But on no account whatever, at- 

 tempt to eradicate these parasitic bodies by means of acid, or 

 acid and water alone, as the chances are that the shell will be 

 completely destroyed by tlieir application. We have seen 

 many fine and valuable shells destroyed by an injudicious 

 application of acids they should never be used when it can 

 possibly be avoided. We have, on the other hand, seen shells 

 which were so completely enveloped in calcareous crust, that it 

 was impossible to trace their external surface, most thoroughly 

 cleared of all this, without being touched at all by acids, the 

 whole being removed by a small knife or other sharp instru- 

 ment ', and these, in many cases, having long and tender spines 

 externally. 



Nothing can be more monstrous than the application of 

 pumice-stone, which some recommend, for polishing shells ; as 

 is also the use of tripoli, rotten-stone ; and imry. Neither do we 



