134 EOCENE MOLLUSCA. 
“ An ovate, elongate, or somewhat quadrate shell, with the anterior extremity rather more 
rounded than the posterior, which is slightly angulated and truncated. ; 
“ The specimen figured has undergone some compression, which has partially modified 
the original form. It was considered, and therefore figured, as a distinct species by Pro- 
fessor E. Forbes; it 1s, however, closely allied to and difficult to distinguish from some 
varieties of U. Solandri.” —Morris. 
Locality. Wempstead Cliff. 
I am much inclined to think, with Professor Morris, that it is only a variety (and that 
not a very distinct one) of U. Solandri. 
4. Unto Souanprl, J. Sowerby. ‘Tab. XX, fig. 11, a, 6. 
Unio Souanpri. J. Sow. Min. Conch., t. 517. 
_— _— S. Wood. Catal. in Lond. Geol. Journ., p. 118. 1847. 
—- — Wright. Ann. and Mag. Nat. Hist., June, 1851, p. 6. 
_ — Morris. Catal. Brit. Foss., p. 230, 1854. 
Spec. Char. U. testaé transversd, oblonga vel subrhomboidali, compressa valdé in- 
equilateral ; pedi-regione rotundatd, siphoni-regione truncald ; valvis tenuibus ; um- 
bonibus vie prominentibus ; dente cardinali parvo, laterali elongato; striis crescentibus 
exilissimis. 
Shell tranversely ovate, oblong, and slightly compressed, very inequilateral ; pedilateral 
margin rounded, the opposite one somewhat angularly truncated ; valves thin ; umbones 
depressed ; cardinal hinge-tooth small, with an elongated lateral tooth ; connexus short ; 
lines of increase very fine. 
Length, \3 inch, breadth, ‘ths inch. 
Localities. Hordwell, Colwell Bay. @ 
Although so common as this shell is at Hordwell, it does not appear to have been 
known to Solander, at least he does not figure it. 
The shell called Mya pictorum, Foss. Hant. fig. 95, referred to in ‘ Min. Conch.,’ vol. vi, 
p. 29, with a?,is probably Cytherea laevigata. The shells at Hordwell are in great profusion, 
but they are exceedingly fragile, and generally exfoliated, so that it is very difficult to obtain a 
perfect specimen. ‘The proportions in magnitude of this shell are generally about two in 
length to one in height, and rather more than half a one in thickness or tumidity. ‘The dorsal 
and ventral margins are nearly parallel, or with a very slight curve inwards in the ventral 
margin, and the siphonal is three times the length of the pedal region. In the right valve 
there is one rather prominent tooth a little on the pedal side of the umbo, and this is 
obsolete in the left valve; the elongated lateral tooth is the reverse of this, being prominent 
in the left valve and obsolete in the right. ‘The oral muscle-mark is of a moderate 
