CRASSATELLA 



TESTA ffiqiiivalvis^ transversa^ insequilatera. Cardo 

 valvse alterius dentibiis diiobiis ; alterius dente 

 unico: denies plerumqiie crassi^ sulcato-rugosi. 

 Ligamentu7n inteniuiii^ foveolse cardinal! in 

 utraque valva insertum. hnpressiones onuscu- 

 lares ducE^ distantes^ laterales. Denies laierales 

 nidli^ aut obsoieti. 



The Crassatellce^ probably on account of their extreme 

 rarity, and also of the general resemblance to Mactrce^ seem 

 scarcely to have attracted the attention of English Concho- 

 logists ; it is true they have not much gay colouring to re- 

 commend them to Collectors, but to such as admire Nature 

 with a scientific eye, and in her more homely attire, they are 

 not totally uninteresting; for to the internal ligament of 

 the Mactrcc they join a general resemblance in form to 

 some of the Donacidea and Veneridea, and, therefore, seem 

 to form a link of union betvt^een those families. However, 

 we do not presume to say, that their resemblance to either 

 is very strong. 



Shell equivalve, transverse, inequilateral, not attached 

 nor gaping. In one valve there are two, strong, cuneiform, 

 rugose, sometimes perpendicularly grooved,'cardinal teeth; 

 and in the other only one. We understand Lamarck to 

 say, there are two in each valve ; but in five or six species 

 which we have examined, we find scarcely any traces of 

 more than one in the right-hand valve. Ligament internal, 

 attached to a concave space placed on the anterior side of 

 the hinge ; this pit, to which the ligament is attached, is 

 divided by a carina into two portions, and that part of the 

 ligament which is attached to the outer portion is visible 

 externally when the valves are closed : two strong oblong 

 depressions may then be observed, one on the anterior 



