316 INTRODUCTION TO CONCHOLOGY. 



of the Fimia, when highly magnified, resembles Eomau 

 tesserse; that of the Unio occidens may be compared to 

 transverse lines, crossing one another ; a vertical section of 

 the Pinna exhibits in its breadth the semblance of water, 

 covered at intervals with the stems of rnshes ; small saucers, 

 irregularly formed and arranged, are presented in the laminse 

 of the shell of OstrcBa edulisj when magnified 250 diame- 

 ters. A section of the M?/a arenaria shows, in one part, 

 distinct cellular partitions, with large nuclear spots; in 

 another portion of the same layer the cell-boundaries 

 become fainter and then totally disappear. Different kinds 

 of shells, such as the Solen, Ariatina, Trigoniaj kc, present 

 the appearance of being covered with metallic crystallizations 

 of great beauty, while the cellular structure of nacre per- 

 taining to the Haliotis splendem reveals a perfect stratum 

 of cells, somewhat resembling the closely-compressed scale 

 of the artichoke. The most exquisite frost-work, in all 

 its varied developments, cannot surpass the effect produced 

 by the membranous residuum of the shell of Terehratula 

 australis, when viewed in different lights ; and those who 

 examine a decalcified membrane of the same species, are 

 forcibly reminded of those dancing figures that celebrate 

 the first of May, in a kind of leafy arbours. 



