SUPPLEMENT TO THE EOCENE BIVALVIA. 

UNIO. Phillipson, 1788. 
For generic character see ‘ Hocene Mollusca (Bivalvia),’ Vol. I, p. 130. 
Seven species of this genus were figured and described by myself in the Volume 
of the Palwontographical Society’s Publications issued for the year 1862, and I 
have here introduced the figure of another form. Some of these were not in perfect 
condition, and will require confirmation by better specimens than any I have seen; 
indeed, one of these shells figured and described under the name of Unio Edwardsiz, 
p. 133, T. XX, f. 16, @ 4, very doubtfully belongs to that genus, the cast only with a 
mutilated specimen being all that I had seen ; but they were so called in Mr. Edwards’s 
cabinet, and I did not feel justified in altering their names, as from their shape I thought 
they might belong to the genus Unio. Another specimen has been obtained from the 
same formation and locality by Mr. C. Meyer, but as this has only the exterior exposed, 
T am still doubtful as to its generic position. It was referred to Cyrena by Mr. Meyer, 
but with a doubt, and as I am inclined to think, in the absence of a view of the hinge 
which the nature of the matrix rendered impracticable, that Mr. Meyer’s view of the 
genus is the more probable, I have figured it under the generic name of Cyrena 
(Tab. A, fig. 15), so that if future specimens should confirm the reference, Unzo 
Edwardsti must be expunged from the list of Eocene Mollusca. 
The genus Anodonta does not so far as I know make its appearance in the Lower 
Tertiaries of England, and only two species are given by M. Deshayes from the Paris 
Basin ; these do not appear to be well established, and the exterior only has he repre- 
sented (see his description, An. s. Vert. du Bas. de Par., vol. i, p. S00). 
Unio Micuavupi? Deshayes. ‘Tab. A, fig 6. 
Unio Micuaupt, Desh. An. sans Vert. du Bas. de Par., p. 802, pl. Ixii, figs. 1—5, 1860. 
— — ? Sandberger. Land- und Siissw.-Conch., p. 177, pl. viii, fig. 1 (cop. 
Desh.), 1872. 
Spec. Char. “ U. Testd variabili, ovato-rotundatd, plus minusve inflato-gibbosd, valde 
inequilaterali, transversim irregulariter rugosa, inaqualiter bis terve undato-gibbosa, sepius 
postice plicis tenuibus, divaricatis ornata ; umbonibus magnis, tumidis, proeminentibus, sub- 
A 
