44 



longitudinal low ridge extending from the cen- 

 tral beaks ; ventral margin arched. 



Syts. Thr^cia convexa, 5" r. Wood, Annals, Sgc. 

 r. 6. 243. (non auctorum.) 



1 HRACIA convexa^ a recent species, is a convex nearly 

 heart-shaped shell, with a straight ventral margin, and 

 beaks nearest the posterior extremity; but still so much is 

 the shell before us like it, that imperfect specimens may 

 easily be mistaken for the same; and Mr. Wood observes 

 in the ' Annals,' that his " specimens are compressed and 

 broken ; too imperfect for identification." Specimens since 

 collected at Sudburn Hall and Ramsholt by the Rev. R. 

 Wilson and Mr. S. V. Wood have enabled us to determine 

 the difference and to give nearly complete figures. A spe- 

 cies more nearly allied to T. convexa is found in the newest 

 tertiary beds of Sicily. 



THRACIA sulcata. 



TAB. DCXXXII.— /g 3. 



Spec. Char. Transversely elongated, oval, largely 

 truncated, compressed, concentrically furrow- 

 ed ; truncated extremity separated by an ob- 

 tuse ridge ; beaks rather nearest to the pos- 

 terior extremitv, hinge callus lanceolate. 



iHE surface of this is composed of grannies, like several 

 others of the same genus ; it is otherwise so distinctly 

 marked that it is easy to recognise it. The specimens 

 figured are in the cabinet of F. E. Edwards, Esq., who 

 tiiscovered them at Bracklesham. 



