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VENXJS incrassata. 
CYTHEREA. Lamarck . 
TAB. CL V.—Fig. l and 2. 
Spec. Char. Orbicular, oblique, subdepressed, 
smooth ; posterior slope straightish ; lunula, 
large, obscure ; edge entire ; a conical tooth 
under the lunula. 
Shell very thick, the anterior slope concave, holding the liga- 
ment ; the central tooth of the hinge thick and blunt, but not 
bifid ; the detached conical tooth which would make it a Cy- 
therea, is small, but sharp, opposed to a corresponding hollow 
in the opposite valve : the lines of growth are fine, and very 
numerous near the edge. 
I received this some time since from the Rev. Mr. Iremonger, 
from Brackenhurst, in the New Forest, Hampshire 5 it is suffi- 
ciently distinct from any other that I know. The specimen is 
very entire, and the two shells were so perfectly locked toge- 
ther by the narrow hinge tooth, between the two most adjacent 
ones in the opposite valve, that it broke in separating them. 
The gloss, in some measure, remains both outside and within, 
the former was apparently brown when fresh, the latter white ; 
both are now stained with grey streaks and blotches. The spe- 
cimens seem to have lain in a loose earth. I should suppose if 
the place were searched it would afford some well preserved 
reliquiae. 
VE^™gibbosa. 
TAB. CL V.—Fig. 3 and 4 . 
Spec. Char. Orbicular, gibbous, with many trans- 
verse rugae ; lunula large and short ; edge sub- 
crenulated ; hinge rather large. 
V enus rugosa is something like this, but that is shorter and 
less gibbous and has a much smaller lunula : its hinge also is 
much smaller : both have rudiments of a tooth under the lunula 
in each valve, but without corresponding impressions. 
I have only received one specimen of this shell, some few 
years since, from Suffolk, and 1 consider it a variety. The 
present active spirit of research will in due time prove if it be 
more common than I expect. It is in a tender chalky state, 
and I conceive it proper to secure it as I think it is sufficiently 
distinguished to be recognized by moderate specimens. Its 
outer coat, with the rugae, which it seems once to have been 
ornamented with, has split away: I cannot, therefore, say 
whether they were like those of V. rugosa or not 
