BRITISH OYSTERS : OLD AND NEW.
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OSTREA COCHLEAR Poli.
Reeve (Conch. Icon, plate xx., fig. 44, a., b.), describes this
shell as "very thin, ovate or suborbicular, foliaceous ; lower
valve very deep."—"Upper valve compressed, with the margin
reflected, radiately striated at the margin." The species is very
irregular in shape, varying from nearly flat specimens, to others
with deep lower valves, as in var. navicularis Brocchi. Nearly
all examples exhibit the foliations or callosities, caused by a
surplus of shelly matter. The shell from the Holmes Collection
exhibits this very strongly. O. cochlear is fairly common in the
East Anglian Crag. The O. spectrum Leathes (Crag Moll., vol.
ii., plate 11., fig., 1 c.) is a variety that shows the foliations
to perfection.
OSTREA DIANAE Monterosato.
This beautiful shell is exceedingly delicate, squarely
built, with oblique, projecting beak-like umbo, but with
the ligamental area narrow and deep in proportion to the
length ; the granulations of the hinge well marked, scar deep,
interior lining opalescent, margin plain. Outside irregular,
with close narrow ribbing, colour reddish purple, with closely
set laminations on the upper valve. Height 55 mm., breadth
35 mm. The shell is not unlike a full grown Mediterranean
example of O. stentina which I possess, but this, al-
though only two-thirds of the size, is stronger ribbed, less
nacreous, and has a different muscle mark, with a crenulated
edge. The authors of the Moll. du Roussillon, vol. ii., plate xiv.,
figs. 1-5, correlated a Corsican shell with a Miocene species
O. boblayi, Deshayes. It does not agree with Deshayes' species,
and has been re-named O. Diana by Monterosato (op. cit., p. 4).
OSTREA VIRGINICA Gmelin.
Attempts have been made to naturalize the American oyster
in British waters, but without success, the general temperature
of the water being too low for successful propagation either by
sowing the spat or by laying down shells of a more advanced
growth, such as were dredged up (dead) by Canon Norman in
Salcombe Bay, Devonshire. On the East coast of England this
operation has enriched our native fauna with several shells, as
for example Petricola pholadiformis, Crepidula fornicata and