CONCHOLOGY. 59 



A. pisolina. A. lactea. 



A. callifera. A. cancellaria. 



A. bisulcata. A. irudina. 



A. senilis. A. rhombea. 



A. auriculata. A. corbicula. 



A. Cayennensis. A. Indica. 



A. antiquata. A. granosa. 



A. Braziliana. A. squamosa. 

 A. pistachia. 



2. Genus Cucullasa. 



.Inimal. As above. 



Shell. Trapeziform, inequilateral, equivalve, heart-shaped ; 

 beaks far apart, separated by the angular groove of the ligament, 

 which is altogether external ; hinge linear, straight, with small 

 transverse teeth, having at its extremity from two to five parallel 

 ribs; valves minutely striated longitudinally; margins crenulated. 

 The CucuUsea is distinguished from the Area by the muscular 

 impression, to one side of which is an auriform testaceous appen- 

 dage; the shell also is more trapeziform. Inhabits the Indian 

 ocean. One living species. One fossil. 



Cucullsea auriculifera. 



3. Genus Pectimculus. 

 Animal, Body round, more or less compressed; mantle with- 

 out cirrhi or tubes ; foot securiform, cleft at its inferior anterior 

 edge ; buccal appendages linear. 



Shell. Orbicular, equivalve, subequilateral ; summit nearly 

 vertical, and more or less distant ; hinge formed upon each valve, 

 of a numerous series of small teeth disposed in a curved line, 

 sometimes interrupted beneath the summit; ligament as in Area, 

 but usually much narrower. Inhabits the British and Mediterra- 

 nean seas. Twenty-two living species. Nine fossil. 



Pectunculus pilosus. Pectunculus pennaceus. 



P. marmoratus. P. castaneus. 



P. angulatus. P. striatularis. 



P. palleus. P. pectinatus. 



P. zonaUs. P. rubeus. 



