408 



MISCELLANEA. 



II. Description of a New Species of CARDiUM/rom the Greensand 

 of Halden Hill in Devonshire. 



Cardium concentricum. E. Forbes. 



a. Under side of valve showing the hinge. 



b. Back (one third linear dimensions.) 



Cardium concentricum. C. testa ovata, tumida, crassissima, 

 in medio sulcis regularibus, subdistantibus, profundis, concentricis, 

 sculptis ; lateribus subcompressis, lasvigatis ; labro integro. 



Length (if perfect), 5 inches. 



Greatest breadth, 3^ inches. 



Height of valves, 2^ inches. 

 This fine shell is described and figured from a single valve, (com- 

 municated by Mr. Austen), which, though imperfect, presents all 

 the essential characters, and beautifully displays the greater part of 

 the hinge, the cardinal and one of the lateral teeth. The shell is 

 elongate and oval, tumid and compressed at the sides. The surface 

 is marked by regular deep concentric striae or narrow sulcations, 

 with broad intervening spaces which are more or less flattened. 

 Towards the sides the striae become gradually obsolete, and the 

 shell only marked by irregular lines of growth. There is a slight 

 indication of an undulation or obsolete furrow, marking the division 

 between the sulcated and smooth portions of the anal half of the 

 shell. The internal margin is smooth. The beaks are slightly 

 incurved. The nearest ally of this species is the Cardium 

 sphceroideum of the Lower Greensand ; of which, indeed, it may 

 be considered representative. 



