72 CONCHOLQGY. 



colle^lors to have fome Shells of each ge- 

 nus in their rough ftate, while the others 

 ihould difplay their beauties by all the ac- 

 complifliments of art : and a more eafy 

 medium may be kept in bivalves, by one 

 fliell or valve being rough, while the 

 other is polilhed. 



Numbers of Shejls have an outer fkin, 

 or pellicle, different from the Shell itfelf, 

 called the Epidermis. ?n regard to Na- 

 tural Hiftory, it is really of ufe to know 

 the nature, colour, &c. of this Epidermis, 

 as It often charadlerifes fome fpecies, as 

 much as any other part. I therefore would 

 recommend a due notice or obfervation on 

 it ; and alfo to preferve fome fpecimens 

 covered with it : to enrich your cabinet 

 with fpecimens for knowledge, as well as 

 for beauty. 



The Epidermis, by its thicknefs, hin- 

 ders a Shell fometimes of being polifh- 

 ed. In that cafe, it mufk be wholly taken 

 off with an acid diluted with water. 



And 



