Pvn H,i I'UitlS

OSTREA. 39
Yar. 2. luppopus.
Shell large and extremely thick. 0.
Mppopus, Lam. An. sans Yert. vii. p. 219.
Yar. 3. deformis.
Shell small, distorted, and often nearly
cylindrical. 0. deformis, Lam. 1. c. p. 229.
Yar. 4. Rutwpina. Shell small, transversely
regular shape.
oval and of a
Yar. 5. tincta. Shell flattened and attached in every stage
of growth ; inside of a rich purplish-brown or olive-green ;
hinge-margins strongly crenulated.
Habitat :
0-45 fathoms, on every part of our coast
from Shetland to the Channel Isles, usually gregarious
beds of various extent. Var. 1 . shells,
and forming On
crabs, and other substances, having
rather a more south-
ern distribution. When this variety is affixed to a ribbed
scallop, it adopts the markings of that shell, but it re-
tains its own colour. It appears to be the 0. depressa
of Philippi. Var. 2. In deep water and solitary. Var. 3.
the crevices of rocks in the littoral and
Occupying
laminarian zones, and called the " rock-ovster." Some
specimens resemble a Gryphcea in shape. Var. 4. Coasts
of Essex and north Kent, in a semicultivated state, and
well known in this country as "natives." Var. 5. West
of Scotland and Burra Isles, Shetland. Mr. Grainger
has noticed this ubiquitous species as "imbedded in
considerable myriads M in a raised pliocene deposit at
Belfast; and, according
to Mr. James Smith and Mr.
Geikie, it occurs in the Clyde beds and other glacial
deposits in Scotland. Red and Coralline Crag (S .Wood) .
The shells may also be seen mixed with those of peculiarly
arctic species in the raised sea-beds near Udde-
valla. It is very difficult to ascertain its foreign distri-
bution, with any tolerable degree of correctness,
sequence of its specific identity being enveloped
in con-
in such
a cloud of different names. Depending, however, on