PULLASTRA. 



Shell equivalve^ transverse, inequilateral, the ante- 

 rior side being the shorter. Cardinal teeth three in each 

 valve, placed near to each other, and generally having 

 their terminations notched ; in a few species the central 

 tooth of one valve is deeply cloven. Muscular impres- 

 sions two, lateral, roundish. Muscular impression of 

 the mantle with a large sinus. Ligament external, partly 

 concealed by the dorsal margins of the valves. 



Several recent species of this Genus are common on 

 our own and other European shores; others are brought 

 from the East and West Indies; some are beautifully 

 marked. Fossil species are scarce, and we believe are 

 only found in the tertiary beds. 



