312 NATURAL HISTORY OF OUR SHORES 



is admissible or not on dried specimens of Crustacea. 

 On the one hand a glairy surface is unnatural and ob- 

 jectionable, on the other, the dull dry surface is equally 

 so, and the fine markings and mottlings that are present 

 cannot be seen. 



My plan has been a compromise, and my specimens look 

 well. I take a little mastic or copal varnish, and thin it 

 to a great extent with benzoline, bringing it to the fluidity 

 of water. A few drops of this applied spreads by capillarity 

 over the whole surface. This brings out the colour and 

 markings, gives an appearance of freshness, and leaves no 

 gloss. 



Mollusca. Preservation in this group really comes under 

 two headings. The very popular branch Conchology re- 

 quires no great skill. It is only necessary to bear in mind 

 that the shells should, as a rule, be those that are taken 

 living. Tide-thrown specimens are usually rubbed and 

 worn by the attrition of sand, so that the very delicate 

 striations and markings are obliterated. 



The ordinary bivalves, and all the univalves, can be readily 

 cleaned out by boiling and removing the flesh (from the 

 latter), by means of a needle, pin, or forceps. But some of 

 the bivalves viz. those that have a fine epidermis on the 

 shell, such as the satin-coated Mactra helvacea must not 

 be boiled, but macerated in cold water until soft. 



The shells should then be wiped dry, very carefully 

 closed (bivalves), and fastened in place until dry, by 

 means of a thread or a slip of paper. Some of the valves 

 should also be left open, to show the teeth, ligament, 

 and marks of muscle attachment. 



In the univalves the operculum should be taken care of, 

 and in some specimens be gummed in its natural position, 

 a little cotton wool having been previously pressed into the 

 sheU. 



The Nudibranch and Opesthobranch molluscs present 



