﻿SUPPLEMENT TO THE BIVALVIA. 



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Cyrena cuneiformis, Gold/. Petr. Germ., t. xi, p. 224, pi. 146, fig. 2, 1838. 



— trigona, Id. Idem., figs. 3, 4. 



— subarata, Bronn. Leth. Geogn., t. xi, p. 958, pi. xxxviii, fig. 2, 1854. 



Spec. Char. C. Testa crassd, ovato-trigond vel cuneiformi, oblique cordatd, 

 i/iaquilaterali, postice angulatd, antice rotundatd, striata, striis transversis imbricatis con- 

 spicuis, postice obsoletis, cardine bidentato, denlibus later alibus Icevigatis. 



Dimensions, lfths by 1-g-th of an inch. 



Localities. Britain : Hempstead, Bembridge {Morris). 

 France: Sables superieurs (Deshayes). 

 Belgium : Klein Spauwen (Nyst). 



This is said by Mr. Morris (' Mem. Geol. Survey,' 1850, p. 146) to be very abundant 

 in Hempstead Cliff, and the specimens to be variable in form ; but this variation appears 

 to be principally in a more or less extension of the posterior side of the shell, some being 

 more elongated than others. It resembles C. cuneiformis in outward form and in its 

 variability, and is intermediate between it and what I have called strigosa, which is 

 strongly and regularly ridged over all parts of the shell. The present species is not 

 only distinguished from the two first mentioned by its exterior markings, but the hinge 

 is narrower, with smaller denticles, the angular ridge on the posterior region is more 

 strongly marked, and the lateral denticles are not striated. In well-preserved specimens 

 there are, as Mr. Morris remarks, from five to seven radiating bands of colour upon the 

 outer surface, such as may be seen on other species of this genus. 



14. Cyrena Britannica, Desk. Tab. B, fig. 2 a, b. 



Cyclas deperdita, J. Sow. Min. Con., tab. 162, fig. 1, 1817. 

 Cyrena — Morris. Cat. Brit. Foss., 2nd edit., p. 200, 1854. 



— Britannica, Desk. An. sans Vert, du Bas. de Par.,t. i, p. 501, 1860. 



Locality. Charlton Soiverby). 



1 have been unable to discover the specimen from which James Sowerby figured 

 and described this species, or to learn of any other specimen having been found, and 

 inasmuch as Mr. Sowerby speaks of it in ' Min. Con.' as a common species at Charlton, 

 I should have supposed that he was labouring under some mistake about it, were it not 

 that his well-known accuracy of delineation precludes the idea of his not having had 

 before him some shell of which his figure is a fairly correct representation ; and as this 

 representation is obviously of some species of the genus Cyrena, and of one unlike any 

 of the others known and described from English Eocene deposits, I have felt it necessary 

 to have his figure copied into my plate, and to give the species among the British Eocene 

 Cyrena. 



