IRIDINA. 



shell, smooth on the outside, showing the strise of growth 

 distinctly; it is rather a strong shell, coated with a thick dark 

 olive green epidermis, beneath which the outer shelly coat 

 is opaque, whitish, and dull, but immediately beneath this 

 and within the shell, is of a brilliant reddish pearly lustre, 

 reflecting the colours of the rainbow. The u?nbones are 

 commonly eroded, as in the greater number of fresh-water 

 shells. This is a shell of very great scarcity, and conse- 

 quently very highly valued. 



