CONCHYLIA— D/TifFR^. 33. 129 



side ; inside chesnut, with the margin plain : hinge with two teeth 

 in each valve, one of them large and the other small. 



33. CB.ASSm A— LAMARCK. 



Testa suborbicularis, eEquivalvis, subwquilateralis, clausa. Cardo den^ 

 tibus duobus in utrdque valvd : lateralibus nullis. Ligamentum ex- 

 ternum, ad latus longius. 



Shell somewhat orbicular, equivalve, nearly equilateral, closed. 

 Hinge with two teeth in each valve : lateral teeth none. Liga- 

 ment external, at the longer side. 



The general outline of this genus, more especially the position of 

 the ligament, will sufficiently distinguish it from the Capsa and the 

 Psammobia. 



* Margine interna integerrimo. 1-2. 

 With the inner margin very entire. 



Crassina testa orbiculo-rhombed, antic^ truncatd, strils transversis ru- sul>»"tomboi- 



dea. 



gosis longitudinalibusque confertis. i. 



Shell orbicular-rhombic, truncate at the anterior side, with rough 

 transverse striae and close lonsfitudinal ones. 



