280 



POPULAR CONCHOLOGY. 



forming a partly detached shelly plate within; hinge 

 straight, with a row of small 

 teeth; ligament external. Ani- 

 mal unknown. — 2 species ; also 

 fossil. 



This shell greatly resembles the 

 Area: the species are found in 

 the sand in the Indian Ocean ; 



the colour of one is a deep cinnamon brown externally, 

 and brown tinged with violet internally. They are easily 

 distinguished by the curious shelly plate for the attach- 

 ment of the anterior muscle. 



Scaphula. Benson, (Scaphura Gray.) — Shell hardly 

 to be distinguished from Area or Cucidlcea. Animal un- 

 known. 



Orthonota. Conrad. — Shell equivalve, almost cylin- 

 drical, bosses turned far towards the front ; the hinge edge 

 straight-lined ; the lower edge parallel to it ; numerous 

 notches in the hinge. 2 fossil species. 



Pectuncultjs. Lam. — Shell nearly round, equivalve, 

 almost equilateral; hinge curve, with 

 a line of teeth diverging on each 

 side, those in the middle being some 

 times incompletely formed; ligament 

 external, epidermis hairy, muscular 

 impressions very deep, pallial entire. 

 Animal orbicular, its mantle freely 

 open, with simple margins which are 

 somewhat enlarged in the branchial 

 and anal regions; foot large, semi- 

 lunar, deeply grooved so as to form a 

 disk with undulated edges ; no bys- 



Pcetuncuhis glycimcris 



