CARDIUM. 



Linn. 



TESTA sequivalvis, subaequilateralis, interdum 

 posticfe hians, costis ab umbone divergentibus 

 lit piurimum ornata; margine interna dentata 

 seu crenulata: dentibus cardinalibus in utraque 

 valva duobiis, approximatis, obliquis, crucia- 

 tim insertis; lateralibus duobus: reraotis, im- 

 pressionihus muscularibus duabus, lateralibus, 

 distantibus; impressionibus muscularibus pallii 

 integris. Liganientum externum. 



Thk Linnean Genus Cardium is so natural an assemblage 

 of related speeies, that it remains nearly, if not altogether 

 in the same state as it was left by that great naturalist ; 

 neither Bruguiere nor Lamarck having thought it desirable 

 to separate any of the species as forming a distinct genus. 

 We have thought one or two fossil species which Lamarck 

 had united to Cardium, more properly associated with 

 Hippopus, our reasons for which we have already explained 

 in our account of the latter Genus. We are the more 

 surprized at this Genus having always remained entire, 

 because the species thus combined vary in general form 

 as much, if not more, than those of any other Linnean 

 Genus, some being nearly globular, others compressed 

 and longitudinal, others much shorter from front to back 

 than they are deep or wide : we beg, however, in saying 

 thus much, to express our entire approbation of this 

 alliance, which appears to us, as far as the shells alone 



