shut. This was formerly considered the proper way to prepare specimens 

 and has some advantages. However, for a study of the mussels it is often 

 an advantage simply to allow the hinge to dry in the relaxed or open 

 position breaking the hinge later when the shells are placed into trays. 



Washing specimens can best be done when one gets back from a trip. 

 One lot, which constitutes all the specimens from one locality, should be 

 cleaned at a time. Most shells can readily be cleaned by the use of a stiff 

 brush, scrubbing the valves under running water. There are, however, 

 specimens that cannot be cleaned that way, particularly shells with iron 

 oxide deposits and other incrustations that accumulate on shells of certain 

 regions of this country. As a rule, specimens badly coated with such 

 deposits clean more easily if placed in a solution of oxalic acid. The solu- 

 tion is made readily by adding a few oxalic acid crystals to some water in 

 a pan. The disadvantage of this treatment is that a little of the nacre on 

 the inside of the shell is often slightly broken down during the period when 

 the incrustations on the outside are being dissolved and loosened. To clean 

 the inside of the shell of the chalk one may apply a little dilute hydro- 

 chloric acid with an old pair of forceps and a small swab of cotton. A 

 thorough brushing and rinsing should immediately follow this treatment. 

 The shells after being washed are placed on a drying rack in cardboard 

 trays. 



Cleaning mussels has its rewards. One certainly finds far more char- 

 acter for identification among cleaned specimens as opposed to those coated 

 with incrustations. In the past, specimens were subjected to a great variety 

 of treatments in order to improve their appearance. Most practices of this 

 kind are unnecessary and in some instances the shells certainly lose their 

 natural appearance, particularly in cases where varnish is applied. Fats, 

 grease and vaseline are recommended by some. If these are used very 

 sparingly there is at times some small advantage in using them, but where 

 they are applied too lavishly they make specimens obnoxious to handle and 

 certainly do not greatly enhance their appearance. 



Cracking among thin-shelled specimens such as Anodonta, and even 

 among some of the heavier forms (such as Lampsilis ventricosa and Lasmi- 

 gona complanata) , has been a serious problem in some instances. Although 

 several methods are in use to prevent splitting, the problem has not been 

 entirely solved. Clench (1931) recommends dipping specimens in a solu- 

 tion of paraffin dissolved in xylol. The xylol evaporates leaving a thin film 

 of paraffin. In some instances this has proven advantageous but there are 

 specimens that continue to check in spite of the paraffin application. Dall 

 (1892: 40) recommends a small amount of vaseline which is rubbed into 

 the epidermis to prevent cracking. Although both paraffin and vaseline are 

 recommended there are opportunities for improvement in this particular 

 problem. 



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