﻿4 



EOCENE MOLLUSCA. 



Length, -j^ths of an inch ; height, § ths of an inch. 



Localities. Britain : Peckham and Sundridge Park. 

 France : Damery, Auvers, &c. 



A few specimens have been sent to me by Mr. C. Meyer with the name of Cyrena 

 intermedia, Morris. They are much more rounded than any of that species in my 

 possession, and appear to correspond with M. Deshayes' figures and descriptions of crassa, 

 to which I have accordingly referred them with a mark of doubt. M. Deshayes gives 

 his species as from the Upper beds. 



This possibly may be the shell that has been called Cyrena obovata ? Sowerby, in 

 Mr. Whitaker's List ('Mem.,' p. 577) from Dulwich, of the Woolwich and Reading 

 series. Possibly, also, the shell figured by Jas. Sowerby, ' Min. Conch.,' Tab. 162, 

 fig. 4, as from New Cross, may be the same as the above. 



2. Cyrena cordata, Morris. Tab. A, fig. 2 a — c. 



Cyrena cobdata, Morris. Geol. Journ., vol. x, p. 158, t. xi, figs. 7 — 9, 1854. 



Spec. Char. " C. Testa subtrigonali, crassa, gibbosd, rugosd ; umbonibus prominen- 

 tibus ; antico rotundato, postico subrostrato, depresso, attenuato." (Morris.) 

 Length, 1^ an inch ; height, If ths of an inch. 

 Localities. Dulwich, New Cross, Charlton. (Meyer.) 



Numerous specimens of this species have been found, and several in a good state of 

 preservation have been obligingly sent to me for examination by Mr. C. J. Meyer, some 

 from Dulwich and others from Sundridge Park. In general they maintain a great 

 uniformity of character, being tumid in the pedal region, but compressed on the other 

 side, with a slightly angular slope on the posterior margin, and a projection at the exit of 

 the siphons. This shell is covered generally with concentric ridges or prominent lines of 

 growth, but I am unable to say whether these are regularly thickened striae, or whether 

 they are the result of irregular decortication, as some specimens are smooth or nearly so. 

 Many of these specimens have from three or four to a dozen rays proceeding from the 

 umbo to the ventral margin, and these rays appear to have been formed from the loss of 

 surface. Probably they were in the living state strongly coloured like some of the 

 Venerida, or like the freshwater shell Galatea radiata, and that the coloured matter 

 caused the unequal decomposition of the surface where they existed. This is not very 

 unlike another well-known shell in respect to these rays, viz. Gnathodon cuneatus, which 

 inhabits brackish water near Mobile, in the Gulf of Mexico, where it is profusely 

 abundant in association with Cyrena Carolinensis. 



Our shell is usually uniform in outline, but all that I have seen have the siphonal 

 side more or less compressed, with a prominent and slightly angular termination. 



