228 J. E. BLAKE ON THE KIMMERIDGE CLAY OF ENGLAND. 



Pholadidea abbreviata, n. sp. PI.. XII. fig. 10. 



Shell widely gaping anteriorly, nearly closed and pointed poste- 

 riorly, breadth -| the height ; ornaments, three strong ribs on the an- 

 terior portion occupying about J the breadth, the second the most 

 prominent. These are succeeded by cancellated stria? on the declivity 

 leading down to the characteristic furrow, which is very oblique, 

 making this declivity a triangle with a broad base ; posterior portion 

 more compressed, first rising again to a strong rib or angle, and 

 followed by a deep valley bounded on the other side by the superior 

 border ; all this portion very obscurely ornamented with cancellated 

 stria? ; breadth f in. 



A unique specimen from the Lower Kimmeridge, Market Easen. 



Leda llneata, n. sp. PI. XII. fig. 12. 



Shell moderately inflated, rounded in front, produced behind to a 

 sharp point with concave sides, the apex of the point nearest to the 

 inferior border ; this border is anteriorly convex, posteriorly con- 

 cave. The superior border is depressed in front ; and there is a 

 swollen line in the portion leading from the apex to the produced 

 point. These two swollen lines enclose between them a lanceolate 

 depression, which is transversely minutely ribbed ; and there is a 

 similar surface not so depressed, with similar ornaments, in front. 

 The whole surface of the shell between these two areas is beaur 

 tifully cancellated by equally regular and conspicuous fine trans- 

 verse and concentric ribs ; posterior side longest ; breadth § in. 



Moderately common in Lower Kimmeridge at Market Easen only. 



Ntjctjla obliqttata, n. sp. PI. XII. fig. 5. 



The whole of the shell is behind the beaks, a nearly straight line 

 leading from them to the inferior border, which is very convex ; 

 superior border nearly straight, posterior end quickly curved ; the 

 beaks are moderately prominent and approximate ; shell without 

 ornament ; breadth J in., f the height. 



Some are less oblique than others. It has scarcely the aspect of a 

 Nucida, but appears to have its hinge. 



Common in the insides of large Ammonites at the top of the Lower 

 Kimmeridge, near Market Easen, also near "Wootton Eassett. 



Cucttll^a pectinata (Ph.).= C. subtexata (Et.). 



Aeca longipttnctata, n. sp, PI. XII. fig. 4. 



Of the general shape of A. rhornboidalis (Cont.). The sides 

 meet the superior border at an angle of 110° ; umbones inflated, 

 eccentric, nearly § from the posterior end, marked off by a moderately 

 prominent keel behind, posterior to which the surface is partly con- 

 cave ; anterior to the keel it is uniformly convex ; inferior border 

 straight or slightly convex ; area between the beaks narrow, obliquely 

 furrowed ; surface covered by broad concentric flattened ribs, with 

 subordinate longitudinal ribs, both much broader than the spaces 

 between them, having a number of elongated pits radiating from the 



