BIVALVIA. 141 



Shell small orbicular, equilateral, convex, concentrically striated, striae close-set, 

 and numerous ; an ovate impressed lunule ; lateral teeth distinct; margin crenulated. 



Diameter, \ of an inch. 



Locality. Coralline Crag, Sutton. 



This species is exceedingly abundant, but restricted, as far as I have seen, to one 

 locality, where, from the prominence of the lateral teeth, the valves are sometimes 

 found united. 



Our shell is furnished with one cardinal, obtuse, triangularly formed tooth in the 

 right valve, and a distinct and distant lateral tooth on each side : in the left valve 

 are two cardinal diverging teeth, with a triangular space between them, also two 

 lateral teeth : anterior muscle mark large, but not very narrow. The striae upon 

 the exterior are rounded, and about as broad as the spaces between them, and 

 the posterior side is marked with an obscure ridge, produced by a slight inflection of 

 the margin on that side, and at the ridge the striae often bifurcate, being less 

 numerous upon the inflected portion. 



A shell in my Cabinet from Bordeaux, which I presume to be Lucina dentata, Bast., 

 appears to differ from the Crag shell in several characters, it is more tumid, rather 

 wider in a contrary direction to our shell, and is more finely striated externally, 

 and has not so distinct a ridge on the posterior side ; the anterior tooth is the 

 more prominent in our shell, and the inside has fine radiating striae, which I do 

 not observe in Basterot's species ; in ours the ligament is wholly external, placed 

 on a prominent fulcrum ; in the Bordeaux shell it is internal, placed obliquely beneath 

 the umbo, and if I am right in the species, belongs to the genus Loripes. 



Lucina striatula, Nyst, may possibly be the same as our shell, though it is distinctly 

 stated by that author to have the margin free from crenulations, but, judging from the 

 locality, his shell may perhaps belong to the older or Bordeaux species. 



From the description and figure of the American fossil by Conrad, I presume his 

 shell to be the same species. We have seen the preceding {borealis) to have a range 

 from the Mediterranean to the Coast of the United States, and there is great proba- 

 bility that the fossil from the Upper Tertiaries of that side of the Atlantic is identical 

 with our own ; it is somewhat singular the author should have chosen for his shell 

 the same name under which the Crag species had passed in my Catalogue, and the 

 coincidence is perhaps the more remarkable, the American fossil having been obtained 

 from Suffolk, in Virginia. 



3. Lucina decorata, S. Wood. Tab. XII, fig. 6 a, b. 



Lucina squamosa? Gold/. Pet. Germ., vol. ii, p. 230, t. 147, fig. 3, a, b. 



Spec. Char. Testa transversa, ovatd, inaquilaterali, crassd, striis radiantibus, et 

 decussantibiis ornatd ; lunula, magna, lanceolatd ; cardine unidentato, dentibus lateralibus 

 perspicuis : umbonibus prominentibus. 



