HEMIPECTEN.— Plate I. 



1 represents the smooth oolourless specimen,— «, 

 interior of the under valve; h, the valve closed, pre- 

 senting the exterior of the under valve ; c the valves 

 closed, presenting the exterior of the upper valve. 

 3. represents the coloured and slightly corrugated 



specimen,- 



interior of the upper valve, 



which 



not shown of the former specimen ; b, the valves 

 closed, presenting the exterior of the under valve ; c, 

 the valves closed, presenting tbe exterior of the upper 

 valve ; d, interior of the under valve ; — all of tht^ 

 natural size. 



