32 EOCENE MOLLUSCA. 
“The Woolwich type of this species is generally smooth ; but I have reason to think that 
the fibrous striated coat is more easily decomposed than the other laminze of the shell, and 
has been therefore generally destroyed. Such appears to have been the case often with the 
Bracklesham individuals ; however, some of the latter, having the fibrous coat, are almost 
free from strize, and others want them over more or less of the surface, which has imduced 
me to consider the striated ones as only varieties of the others.” (Sowerby in Dixon.) 
In support of the above remark, I may observe, that some of Mr. Edwards’ specimens 
from Bracklesham show the upper valve to be quite free from ornament; others are 
fully covered over with numerous fine striae; and one specimen unites these two varieties, 
the younger half of the upper valve being covered with striee, and the lower or older por- 
tion being quite plain; both parts are apparently without decortication. 
O. angustata, Desh., in many characters strongly resembles this species ; but it appears 
rather more attenuated in the hinge than any of our British specimens, although such a 
difference as this may be accidental. In the representation of the French shell are a few 
depressed and irregular ribs, and the shell is free from striz, but there are vestiges of 
radiating plicee or obsolete ribs in our species. 
The full-grown specimens may be said to have proportions generally of about three to 
one, but a full-grown specimen in Mr. Edwards’ cabinet is not more than two to oneanda 
half. In the young state the shell is often nearly orbicular, becoming elevated as it increases 
in size. One of our specimens has a very pointed umbo, and this is somewhat recurved. 
21. Osrrea Vectiensis, Forbes MSS. Tab. VII, fig. 5, a—c. 
Osrrea Vectensis. Morris. Mem. Geol. Surv. pp. 68, 150, t. 3, fig. 9, 9 a, 9b, 1856. 
— — Id, ‘Cat. Brit. Foss., p. 175, 1854. 
Spec. Char. “ Testd ovato-trigond, oblongd, attenuata, sub-angustd ; ared cardinal 
Jossulad triangulari, latd, recurvd exaratd ; umbonibus obtusis ; valvd superiore lineis incre- 
ments numerosis ornatd ; valvd majore crassa, cvtis rugosa.” 
An oblong and rather narrow shell, with the larger valve somewhat thick and externally 
rugose ; the upper valve flat, thin, recurved at the umbo, and marked by numerous con- 
centric lines of growth ; ligamental area broad and triangular.” (Morris.) 
Longest diameter, 13 inch. 
Locality. “‘ Sandy beds of the Bembridge series.” (JZorvis.) 
This species does not appear to be rare; several specimens are in the Museum in 
Jermyn-street. 
The right valve has occasionally crenulations in the margin near the hinge; but 
s this valve is often quite free from them; the form of the shell is also exceedingly 
