﻿SUPPLEMENT TO THE BIVALVIA. 



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3. Cyrena cdneiformis, /. Sowerby. Tab. A, fig. 3 a — c. 



Cyclas cuneiformis, J. Sow. Min. Conch., t. 162, figs. 2, 3, 1817. 

 Cyrena — Desk. Coq. foss. des Env. de Par., vol. i, p. 122, pi. xix, 

 figs. 1, 2, 20, 21, 1824. 



— — Sandb. Land- und Sussw. -Conch., p. 181, t. viii, figs. 6 a, b, 



1872. 



— — Morris. Catal. Brit. Foss., 2nd edit., p. 199, 1854. 



— — J. Lowry. Chart. Brit. Tert. Foss., pi. iv, 1866. 



— donacialts, Desk. Diet. Class. d'Hist. Nat., t. v, p. 290, 1824. 



Spec. Char. C. Testa transversa, trigonuld, inaquilaterali, irregulariter substriatd ; 

 untice truncatd, postice angulatd ; dentibus cardinalibus tribus, dentibus lateralibus inaquali- 

 bus perpendiculariter rugosis ant striatis. 



Length, y§ ths of an inch ; height, f ths of an inch. 



Localities. Britain : Charlton, New Cross, Dulwich. 



France : Lignites, and Sables raoyens. 



This is an abundant species in the Woolwich beds of this country ; and it is said by 

 M. Deshayes to be profusely spread in the Lignites and Sables moyens in France. The 

 locality of Headen Hill is given in the ' Coq. Fos. des Env. de Par.,' Tab. 1, p. 123, but 

 I have not been able to see a specimen of this species from the Isle of Wight, nor have 

 I heard of its having been found there. Possibly C. semistriata may have been mis- 

 taken for it. The impression by the mantle exhibits a small and shallow sinus. 



The variation in this species consists in an extension of the siphonal side, one variety 

 being more inequilateral than the other. It somewhat resembles the recent species 

 Cyrena Floridensis. 



4. Cyrena strigosa, S. Wood. Tab. A, fig. 4. 



Spec. Char. C. Testa transverse trigonatd, incequilaterali, regulariter circinatd vel 

 striata, striis magnis acutis, antice rotundaid, postice angulaid elongatd ; dentibus 

 cardinalibus tribus, dentibus lateralibus striatus. 



Length, If ths of an inch nearly; height, fths of an inch nearly. 



Locality. Charlton. (S. Wood.) 



This species is equally abundant with C. citneiformis. It has the exterior covered 

 with regularly concentric striae or ridges, rounded and distinct ; whereas in cuneiformis 

 the lines of growth are indistinct or irregular, and sometimes scarcely perceptible ; and 

 these differences appear to me to justify a specific separation. The angular ridge over 



