520 REV. G. F. WHIDBOENE ON SOME EOSSILS 



Mytilus gradatus, Terq. & Jourcl., is squarer in shape, with more 

 broken radiations. 



Aeca ^quata, n. sp. 



Shell very transverse, attenuated behind, smooth, excepting indis- 

 tinct lines of growth. Umbo nearly central, depressed along its centre, 

 elevated, incurved, rather slender, distant, but not extremely so, very 

 slightly facing forwards. A prominent subacute angle runs down 

 from the posterior side of the apex to the infero-posterior corner of 

 the shell, the posterior wing which is defined by this being very con- 

 cave. Hinge-line somewhat concave by its extremities being raised ; 

 anterior and posterior sides inclined obliquely to it, and parallel to 

 each other. Inferior margin slightly concave in the middle. 



Locality. Leckhampton. There is a specimen in the British 

 Museum from the freestone of the MurcMsoni-heds of that hill. 



Dimensions. 6 lines long, 14 wide, and 3 deep for the single 

 valve. 



The keeled and central beak joined to the great width distinguish 

 this shell. 



It is much like Cucullrea ferruginea, lycett, ' Cotteswold Hills,' p. 

 125, in general shape, but differs from that species in being smooth. 



Aeca culmotecta, n. sp. Plate XVIII. figs. 1, la. 



Shell very transverse, quadrately ovoid, moderately convex. Um- 

 bones very small, moderately distant, anterior (situate about one 

 third of the width from the anterior side), facing forward, much flat- 

 tened, so that the back of the shell is flattened and bounded by two 

 rather sudden convexities as it sinks to the wings. Hinge-line 

 about two thirds the width of the shell, with numerous oblique teeth 

 on each side, those in front being the closest. The corners of the 

 hinge-line somewhat rounded, especially the rear one, the side mar- 

 gins meeting them obtusely. The anterior margin nearly evenly 

 convex, the inferior margin nearly straight, but curving very sud- 

 denly round its posterior corner, after which the margin goes 

 obliquely to the hinge-line. 



Surface covered by small, close, rounded, smooth rays, occasionally 

 dichotomizing ; growth-lines distant, more or less distinct, in some 

 specimens hardly breaking the rays. 



Two specimens from Dundry, in the Bristol Museum, and two 

 (one from Dundry and one from Cold Comfort, near Cheltenham) in 

 the British Museum. 



Dimensions of each valve, 11 lines long by 23 wide, and 4 deep. 



This shell seems to be distinguishable by its very small and prox- 

 imate umbo, and by its crowded even rays. 



Area ovata, Buckm., in Murchison's ' Geology of Cheltenham,' 

 bears some slight resemblance to this shell ; but it would appear 

 to be distinct on account of the more central and pointed umbo, and 

 the much more distant striae. Buckman's name, moreover, appears 

 to have been before used by Gmelin, as well as by Sowerby in 



