CUCULUEA. CONCHIFERA. 93 



A. senilis, Lin. Shell obliquely heart-shaped, tumid, with remote 

 broad longitudinal ribs, and the margin plaited ; apices recurved 

 and distant ; colour white. 2 to 3 inches long, and as much broad. 

 Inhabits coasts of Africa and America. Lister, pi. 238, fig. 72. 



Fossil species of this genus are found in Britain in the carboniferous and magnesian 

 limestone, oolite, chalk marl, and London clay. Fleming's Brit. An. 398, 3U9. 



Gen. 13. CTJCULLJEA, Lam. Area, Gmel. 

 Shell equivalve, inequilateral, gibbous, with the beaks separat- 

 ed; muscular impression anterior, forming an angular or eared 

 border ; hinge linear, straight, with small transverse teeth, and 

 from two to five small parallel ribs at their extremity ; liga- 

 ment external. 



C. auriculifera, Lam. Shell obliquely heart-shaped, ventricose, with 

 decussated striae ; hinge with two parallel ribs or teeth at each 

 end ; colour reddish brown, with a violet tinge within. 2^ inches 

 long. Inhabits Indian Ocean. Chem. vii. pi. 53, fig. 526, 527- 

 Fossil species of this genus are found in Britain in the green -sand and oolite. 



FAMILY IV. CARDIACEA. 



Primary teeth irregular, either in their form or situation, and in 

 ; general accompanied by one or two lateral teeth. 



The greater part of this family are furnished with longitudinal ribs, and are of a 

 heart-shape when viewed anteriorly. There are three primary teeth in the hinge, of 

 which those on the sides are divergent. 



Gen. 14. ISOCARDIA, Lam. Chama, Lin. 

 Shell equivalve, cordiform, ventricose, with the beaks much se- 

 parated, divergent, and turned spirally to one side ; two pri- 

 mary flattened teeth under the beak, and an elongated lateral 

 one under the ligament ; ligament exterior. 



I. cor, Lam. Shell heart-shaped, globose, smooth, brown, with the 

 beaks clouded with white ; umbones very prominent. 4 inches 

 long, and nearly as broad. European seas. B. Brown's Illust. 

 pi. 24, 25. 



Fossil species of this genus are found in Britain in carboniferous limestone, oolite, 

 and London clay. 



Gen. 15. HIATELLA, Daud. Mya, Solen, Lin. 

 Shell equivalve, inequilateral, transverse, gaping at the upper 

 margin ; hinge with the teeth obscure, or a small tooth ill 

 one valve, received into a cavity in the other ; ligament ex- 

 terior. 



H. Arclica, Lam. (Mya Arctica, Solen mlnutus, Lin.) Shell trans- 

 versely oblong, and the apex truncated, with two diverging spi- 

 nous ridges. \ to \ inch long, and 1 inch broad. Inhabits Bri-i 

 tish seas, at the roots of fuci. Mont. Test. pi. 1, fig. 4. 



H. rugosa, Flem. (Mytilus rugosus, Lin.) Shell rounded before, 

 subtruncated behind, with a slight constriction towards the middle 

 of the ventral margin. ^ inch long, and 1^ broad. Inhabits coasts 



