EXPLANATION OF THE PLATES AND WOOD-CUTS. 



this shell, they have been mostly sections in various oblique directions, so that we 

 have been unable to determine satisfactorily its shape or the form of its septa; all 

 that we can ascertain is, that the general form of the shell is a depressed spheroid, 

 with a large angular umbilicus, sinuated septa, and a smooth surface. It does 

 not agree with any described by Count Munster. 

 Loc. Venn Quarry ? 

 Fig. 9 represents, upon the same mass with a specimen of G. carbonarius, two small 

 individuals which resemble the G. stenolobus of PhiUips, (Geol. of Yorkshire, 

 PI. XX. f. 7-9.) ; but they are still more globose, have a finely striated surface and 

 a small umbilicus. 



Plate LIII. 

 (Fossils from Barnstaple, Petherwin, Ilfracombe and Marwood.) 

 Fig. 1 and 2. Pecten nexilis. Suborbicular, slightly convex, inequilateral, finely ra- 

 diated ; ears large, nearly equal, that on the anterior side less distinctly radiated 

 than the other ; ribs very numerous, elevated, smooth, and thin. 



A pretty species, of which we have seen only one or two specimens. It occurs 

 with LeptcBna caperata (fig. 4) and several other shells in slate from New Ifracombe 

 near Barnstaple, and Barnstaple. 

 Fig. 2 is a magnified view of the same. 



Fig. 3. Pecten transversus. Transversely obovate, very slightly convex, radiated, 

 radii in threes, crossed by numerous regular lines of growth ; ears large and nearly 

 equal. Length about 1 inch, width nearly 1| inch. 

 The great width of this shell is a prominent feature. 

 Loc. Barnstaple. 

 Fig. 4, Leptcena caperata. Half-elliptical, very convex, concentrically wrinkled, spi- 

 nose, margin not much deflected ; one valve very convex, the other almost equally 

 concave ; hinge-hne rather longer than the width of the shell ; spines adpressed, 

 those near the hinge-line very long. The concentric rugae are lost towards the 

 centre of the shell. 



Loc. Abundant at Barnstaple and Petherwin ; also in New Ilfracombe Road, 

 near Barnstaple. 



This species a good deal resembles L. scabricula (M.C. t. 69, f. L), but is well 

 distinguished by the numerous concentric rugas and the smallness of its spines. 

 Fig. 5, 16. Leptcena sordida. Transversely elongated, rather convex, irregularly striated, 

 hispid ? muscular impressions occupying half the internal area ; hinge-line nearly 

 as long as the width of the shell, its angles rounded. Width variable, sometimes 

 nearly double the length. 



Of this shell we have but very imperfect specimens, and the exterior is badly 

 preserved ; the portions which remain show it to have been very irregular. 

 These specimens have been inadvertently engraved with fossils from Barnstaple. 

 Loc. Linton. 

 Fig. 6. Atrypa oblonga. Oblong-oval, convex, smooth ; front produced, elevated ; 

 the elevation narrow. 

 Loc. Barnstaple. 



