EXPLANATION OF THE PLATES AND WOOD-CUTS. 



Fig. 10. Pholadomya angulata. Subtrigonal, gibbose, ornamented with four or five 

 sharp ribs, which are most prominent near the edge ; anterior side straight, nearly 

 flat. Length and width equal ; in some specimens 2 inches. 



Ph. «w^?</a^« approaches Ph. Murchisoni var. of Phillips. (Geol. of Yorks., 

 PI. VIL f. 9.) 



Loc. near Charee. 

 Fig. 11. Amphidesma? ovale. Transversely elongate, ovate, convex, slightly wrinkled, 

 anterior side small, truncated, distinguished from the rest of the shell by a gentle 

 depression ; posterior extremity rounded, rather pointed. Length ■ 1 1 lines, 

 width 1 inch 4 lines. 



Loc. near Charee. 



There is no proof whatever that either this or the following belong to the genus 

 Amphidesma ; they are, however, very nearly related to A, donaciforme and Ai 

 securiforme of Phillips. 

 Fig. 12. Amphidesma "i Mans. Transversely elongated, convex, slightly wrinkled; 

 sides gaping; the anterior small, separated from the rest of the shell by an obscure 

 depression ; the posterior rounded, a little flattened. Length 1 inch, width more 

 than If inch : the specimen being broken we have not the measure complete. 



Loc. near Charee. 

 Fig. 13. Corhida lyrata. Rounded, triangular, convex, transversely ribbed ; ribs about 

 15, prominent, rounded ; posterior side of the larger valve formed into a distinct 

 lobe, convex, nearly smooth — the beak of the same valve much incurved, the 

 margin toothed. Length and breadth nearly equal, sometimes exceeding half 

 an inch. 



Occurs grouped in dense masses with Trigonia Pullus, a smooth Uncula, &c. 



Loc. near Charee. 

 Fig. 14. Astarte unilateralis. Transversely obovate, anteriorly truncated, convex, 

 rather flattened and marked with 8 or 9 concentric rugae near the beaks. Anterior 

 side at right angles with the hinge line ; lunette concave, ovate, pointed. Width 

 greater than the length, but variable in proportion, generally about \\ inch. We 

 have given a view showing the lunette on the right hand. 



Loc. near Charee. 

 Fig. 15. Astarte pisiformis. Nearly globose, with pointed beaks; marked with 8 or 

 9 sharp transverse ridges ; edge toothed. Length 3 lines. 



Loc. near Charee. 

 Fig. 16. Trigonia costata, var. This shell varies slightly both in form and markings — 

 generally the form is between that of T. costata, Parkinson or M. C. t. 85 ; and 

 T. elongata, of M. C. t. 431 ; which Lamarck, apparently with justice, considers 

 to be but one species. 



Loc. near Charee. 

 Fig. 17. Trigonia Pullus (M. C. t. 508, f. 2, 3.) ? The markings on the posterior side 

 are not so regular as in the English specimens, but there is no other difference. 



Loc. near Charee. 



