244 PROF. E. FORBES ON LOWER GREENSAND FOSSILS. 



This little Cardium is more or less rounded in outline, nearly 

 ^equilateral and inflated. The surface is marked by very fine 

 longitudinal ribs, so small that the lens is required in order to see 

 them distinctly. On these ribs are very minute transverse 

 squamae. The margin is denticulated by the ribs, and the beaks 

 are more or less acute and prominent. The cast is quite smooth. 



Loc. Common in the Cracker bed at Atherfield. 



42. Cardium Benstedi. Sp. nov. 



I have applied this name to a small suborbicular, subdepressed, 

 longitudinally ribbed Cardium found at Maidstone by Mr. Bensted. 

 It is very distinct from any other Lower Greensand species, but 

 better specimens are required before it can be figured. 



43. Cardium \_Hemicardium~\ ? Austeni. Sp. nov. PI. 3. f. 3. 



C. testa, lanceolata, valde obliqua, carinata, latere anali 

 truncata longitudinaliter striata ; striis in parte anali pro- 

 fundioribus, reliqua testa obsoletis ; umbonibus prominentibus 

 incurvis, submarginalibus. 



Lon. 0^- ; Lat. 1^ unc. 



This remarkable and beautiful fossil, which I have provisionally 

 placed in the subgenus Hemic ardium of the genus Cardium^ is 

 very oblique, convex, and sharply carinated obliquely, with re- 

 curved submarginal beaks. The surface is marked by very fine 

 longitudinal ribs, which in some specimens appear to be alter- 

 nately larger and smaller. The carination bounding the abruptly 

 truncated side is formed by one of these ribs, more prominent than 

 the rest. 



Loc. Peasemarsh, Atherfield. 



44. Trigonia caudata Agassiz. (D'Orb. T. C. pi. 287.) Trigonia. 



scabra of British authors, not of Lamarck. 



Loc. Atherfield, Peasemarsh, Hythe, Shanklin. 



45. Trigonia carinata Agassiz. (T. harpa Desk, in Leym. 



pi. 9. f. 7.) 

 Loc. Hythe, Culver. 



46. Trigonia aliformis Parkinson. (Sow. M. C. t. 44.) 

 Loc. Atherfield, Parham, Shanklin, Sandgate. 



47. Trigonia spinosa Parkinson. (Sow. M. C. t. 86.) 



Syn. T. ornata of D'Orbigny. Identified by a comparison of 

 specimens. 



Loc. Sellinge, Maidstone. 



48. Trigonia dcedalea Parkinson. (Sow. M. C. t. 88.) 

 Loc. Atherfield, Reigate. 



Note. Specimens sent to M. d'Orbigny were identified by him with the 

 Trigonia rudis of the Pala?ont >logie Frar^aise. 



