BRITISH OYSTERS : OLD AND NEW.
213
make it a living French oyster. Locard (Prodrome 1886, p.
578) mentions O. obesa as a French species which is later on given
by him as a synonym of O. stentina.
OSTREA CANVEYENSIS, sp. nov.
Mr. Spurrell (Arch. Journ., vol. xlii., p. 1885), referring to
the quantities of oysters on the margin of the Thames Estuary,
mentions a shell bank on the eastern spit of Canvey Island. A
small series which I have had sent me from that locality exhibit
certain features which ally them to the small Mexican shell
O. mexicana, Sav. (Reeve op. cit., pl. xvi.),with which, fig. 35,
they have much in common, and in less degree to the hollow-beaked
Ostrea cucullata group. The shells are small, as if stunted, full
grown, and very irregular in outline, and are all more or less
attached by the under valve, which is the longest and, so far as
exposed, coarsely corrugated. Upper valve flat or slightly ovate,
beaks prominent, hollowed under hinge. Colour dead white
striped with purple, margins deeply dentellated and coloured.
My largest example measures length 75 mm. by breadth 50 mm.
A solitary example that I obtained from Foulness measured
95 mm. by 70 mm. The interior is white with a coloured scar
(plate xvii., fig. 24).
OSTREA ADRIATIC A Lamarck.
My attention was called many years ago by Messrs. Etheridge
and Bennie to a marine deposit at Cocklemill Burn, on the shores
of Largo Bay, in Fife (for details see "Marine Accumulation
Largo Bay, &c.," Proc. Roy. Phys. Soc, Edinburgh, 1890, 1893),
which has yielded, besides other organisms, 155 species of
shells. 13% of these are not known as inhabitants of the recent
Firth of Forth. Since then I obtained at Mr. Damon's sale,
amongst others, a group of oysters of very irregular shape and
proportion as compared with any other known in these islands,
including the name shell O. adriatica as figured in the Moll. du
Roussillon, pl. ii., figs 5 and 6, and its varieties alata and falcata
both figured by Monterosato, op. cit., pl. ii., figs. 1-4.
The Scotch shells are more or less corrugated and the surface
is very irregular. The upper valve is plain, immediately fol-
lowing the contour of the under valve, but leaving a deep breadth
of margin strongly crenulate at the hinge area. Apex acute,