46 ftlOLLUSCA FRO^I THE CRAG. 



This elegant and fragile shell is by no means rare in the Coralline Crag at Sutton, 

 but rather less so at Ramsholt. Walton Naze is the only locality in the Red Crag 

 from which I have seen it. There cannot, it is presumed, be any doubt about the 

 identity of this species, which does not seem to possess even a local variation. 



The striaj which ornament this shell are sometimes regular in size, but more often 

 possess an intermediate smaller one ; there is a very slight opening between the valves, 

 near the hinge line on the posterior side, and the valves do not quite close on the 

 anterior side towards the ventral margin ; hinge line rather short, with a large and 

 broad ligamental pit projecting inwards ; a subcircular impression by a large adductor 

 muscle towards the convex or posterior side of the shell. 



4. Lima plicatula, S. Wood. Tab. VII, fig. 4. 



Lima plicatula. S. TFood. Mag. Nat. Hist., New Series, vol. iii, p. 235, pi. 3, fig. 4, 1839. 



Sjjec. Char. Testa mi nutd,inaqiiilaterali, oblique-ovata, compressiuscidd ; costato-driald^ 

 str'm 14 — 16 convexis, scabriiisculis ; antich redd, postice rotundatd ; auriculis valde 

 DKBfjuaUbiis ; cardine obliquo ; area liffamcnti minutd ; in auriculis dentibus obtims. 



Shell small, inequilateral, obliquely ovate, slightly compressed ; costated or 

 striated; strise 14—16 rounded and somewhat scabrous; anterior side straight, 

 posterior rounded ; auricles very unequal ; hinge line oblique ; ligamental area 

 small, with an obtuse tooth in the centre of the auricles. 



Lonyest diameter, T,th of an inch. 



Locality. Cor. Crag, Sutton. 



About a dozen specimens of this shell are in my cabinet, but none of them in vciy 

 j)crfcct condition ; and I have not seen other specimens, since the publication of it in the 

 ' Mag. Nat. Hist.,' to give further assistance in its elucidation. It appears, however, 

 to present characters differing from any other species with which I am acquainted, 

 and it must, for the present at least, be considered as distinct, and may be more 

 ])articularly described thus. 



The shell is very oblique ; the anterior straight, sloping from the umbo with a 

 scarcely perceptible auricle on that side ; while the posterior is not only roimded, but 

 has a comparatively large and projecting ear : it appears to have been able almost to 

 close the valve, or at least to have had a very slight gape, as the edge of the shell 

 nearly touches all round when laid upon a flat surface with its exterior uppermost ; the 

 rays are rounded, slightly scabrous, and numbering about 17 or 18, and these are 

 somewhat broader than the spaces between them, which are prettily ornamented with 

 elevated ridges, giving it a cancellated appearance. The hinge is rather peculiar, 

 the central depression or pit being small and very oblique ; and on each side in the 

 middle of the anriclcs is a tooth-like projection with a corresponding depression in the 

 opposite valve ; a similar character may be observed in other species of this Genus, 

 where interlocking prominences and depressions are formed by the animal as an 



