192 THE ESSEX NATURALIST.
semiorbiculata membranis imbricatis undulata, valvata altera
plana," Habitat Oceano Europea is vague, and his later or other
references are little better. Linne's own collection, now in the
possession of the Linnean Society, contains but two oysters that
need be referred to here. One is O. crista-galli, the other a
coloured and foliated shell identical with that figured by Messrs.
Bucquoy, Dollfus and Dautzenberg (in the Moll. Mar. Roussillon,
vol. ii., pl. 2, fig. 22) as O. edulis, var. cristata.
Of the numerous figures Linne referred to, the most reliable
is that of our own countryman, Dr. Martin Lister, who had
described and figured a British oyster, as Ostreum vulgare, as
early as 1657 in his Historia Conchyliorium, the figure being
repeated in the Hist. Anim. Angliae, 1678, tab. 4, fig. 26, which
Linne refers to. It represents an adult shell with a roughly
or closely ribbed under valve, foliated at the circular growth-
lines, similar to those I have from Mersea Island.
Authors are not only divided as to the true Linnean type
of O. edulis, but also as regards its geographical range. Jeffreys,
in his Brit. Conch., vol. 2, gives it from Iceland on the authority
of Mohr, 1770, but all Northern writers repudiate Mohr's state-
ment as being made on a doubtful record. The shell is not known
farther north than Drontheim. Odhner does not record it in the
Marine Mollusca of Iceland (Arkiv. for Zoologie, 1910), neither
does Prof. A. Jensen in the Danish Ingolf Expedition, Copen-
hagen, 1912, who expressly says that Jeffrey's reference is
founded in error. Its most northern locality is in the Faroes,
where a young individual 8mm. by 10 mm. was dredged attached
to a modiola. As no banks of these shells are known to exist
there, it probably came from the Shetlands, where they were
once very abundant.
McAndrew (Rep. Brit. Assoc, 1856, p. 135), says it is "subject
to much variation, but the common English or Welsh oyster is
certainly abundant at the head of Vigo Bay and I have dredged
it off Cape Trafalgar and Malaga, but have not noticed it further
east in the Mediterranean"; and Jeffreys (Ann. & Mag. Nat. Hist.
1856), says "I certainly never met with the common form of
our oyster, whether native, Welsh, or "rock"3 in the Medi-
terranean, nor is it mentioned by Philippi, or Payraudeau as a
recent species." Later, in the Brit. Conch., vol. 2 1863, Jeffreys
3 The term "Rock" simply means that the variety was taken on rocky ground.