134 EOCENE MOLLUSC A. 



" 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 is, however, closely allied to and difficult to distinguish from some 

 varieties of U. Solandri." — Morris. 



Locality. Hempstead Cliff". 



I am much inclined to think, with Professor Moms, that it is only a variety (and that 

 not a very distinct one) of U. Solandri. 



4. Unio Solandri, J. Sowerby. Tab. XX, fig. 11, a,b. 



Unio Solandri. J. Sow. Min. Conch., t. 51". 



_ _ 5. Wood. Catal. in Lond. Geol. Joum., p. 118. 1847. 



— Wright. Ann. and Mag. Nat. Hist, June, 1851, p. 6. 



— — Morris. Catal. Brit. Foss., p. 230, 1854. 



Spec. Char. U. testa transversa, oblongd vel subrhomboidali , compressd valde in- 

 fsquilaterali ; pedi-regione rolundatd, siphoni-regione Iruncatd ; valvis tenuibus ; nm- 

 bonibus vix prominentibus ; dente cardinali parvo, laterali elongato ; striis creseeniibus 

 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 ; conncxus short ; 

 lines of increase very fine. 



Length, If 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 Mga 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 



