CAEDIITM. 99 



bone has no existence. In the former, all the shells are inequi- 

 valve ; in the latter equivalve. And M. Deshayes, considering 

 that the valves are equal, and that there is no separate bone to 

 the hinge, is of opinion that the genus ought to be placed near 

 the Lutrariae, and not far from the Anatinse. C. semisulcata, 

 pi. xsiv. fig. 501, 2. 



CAEDIJN'AL MARG-IN. The edge of a bivalve shell on which 

 the teeth is placed. 



CARDINAL TEETH. The teeth upon the hinge directly beneath 

 the umbones of a bivalve shell, as distinguished from the lateral 

 teeth, which are placed at a distance on each side. In Venus, 

 fig. 119, the cardinal teeth are marked by the lettqr e. 



CARDIOCAEDITES. Bl. A genus separated from Cabdita, 

 Auct. Thus described, (translation) *' oval species, with the 

 inferior margin nearly straight, or a very little inflated, crenn- 

 lated and completely closed. Ex. La C. Ajar, Adans. Seneg. 

 pL xvi. fig 2." 



CARDISSA. Megerle, 1811. A genus composed of those species 

 of Carditjm Auct. which are heart-shaped. Kv. C. dionaeum, 

 fig. 122. And C. Cardissa. 



GAELITA. Brug. 1789. Fam. Cardiacea, Lam. Submytilacea, 

 Bl. — Bescr. Equivalve, inequilateral, ovate, subquadrate or 

 oblong, marked externally by ribs radiating from the umbones 

 and terminating in a crenulated margin on the inner surface ; 

 cardinal teeth in one valve, one long, thick, oblique ; another 

 short, more straight ; in the other valve one long, oblique, thick. 

 Muscular impressions two in each valve, rather oval ; palleal 

 impression not sinuated, . — 05*. This description includes 

 Lamarck's genus Yenericardia, which, although consisting of 

 the more oblong species, is not considered sufficiently distinct 

 to justify the separation. Cypricardia is distinguished from this 

 genus by a remote lateral tooth. Mediterranean, Africa, East 

 Indies, &c. Cardita calyculata, fig. 124. 



CAEDIUM. Linn. Fam. Cardiacea, Lam. Conchacea. Bl, — 

 Bescr. Equivalve, sub-equilateral, sometimes gaping posteriorly, 

 ornamented on the outside by ribs radiating from the^imbones ; 



H 2 



