THE MOLLUSCA 963 



inside and outside of the shell should be removed by thorough 

 washing. All the water species are apt to be more or less incrusted 

 with deposits of lime or oxide of iron. These can be removed by 

 immersing them in oxalic acid. Care should be taken not to pro- 

 long the operation, or the texture of the shell may be injured. 

 Elbow grease is the most effective agent for making good specimens. 

 When that fails, use the acid. The Ancyli are always more or less 

 coated in this way, and can easily be cleaned by floating them for 

 a few minutes on the acid, upside down, and then gently brushing 

 them off with a soft brush while held on the tip of the finger. 



The larger bivalves should be well washed and, if necessary, 

 scraped off with the knife as soon as taken, care being taken not 

 to injure the epidermis. 



They can be boiled, if desired, when the shells will open and the 

 animals easily removed. But, as a rule, it is more convenient, 

 unless collected in large quantities, to cut the muscles, which hold 

 the valves together, with a thin-bladed knife and scrape the animal 

 out. Care should be taken not to break the edge of the fragile 

 species when inserting the knife. All traces of the animal matter 

 should be removed, and after a thorough washing the valves tied 

 together with a string until thoroughly dried. Never use colored 

 twine for this purpose, as it is apt to stain the shells. Any surface 

 incrustation can be removed either with oxalic or muriatic acid. 

 The latter is more convenient for the larger species, and can be 

 applied with a small brush. To avoid trouble, it is safer to wear 

 rubber gloves, if a large quantity of material is to be cleaned. Care 

 must be exercised in using the acid and the specimens frequently 

 washed, lest damage be done to the shell. The smaller bivalves, 

 the Sphaeria and Pisidia, are best treated by putting into diluted 

 alcohol for a day or two and then drying them. If left too long 

 the shells are apt to open, which interferes with the looks of the 

 specimens. The larger species of Sphaerium are better with the 

 animal removed. This can be done after boiling, or a few days 

 in alcohol. As these are usually too small to be easily tied together 

 to keep the valves from gaping, each specimen, while the hinge is 

 flexible, should be closely wrapped up in a small piece of tissue 

 paper until completely dry. 



