Pvn H,i I'UitlS

Beechey has dredged
LEDA. 157
it alive in 145 fathoms off the
Mull of GaUoway. It occurs in all our upper tertiary
deposits, although in all probability an allied species
(L. pernula, Miiller) has been often mistaken for it in
has a more
compiling lists of fossil shells. The variety
southern habitat, and is found on all the English, Welsh,
as well as at Oban and in the Hebrides.
and Irish coasts,
Both the typical form and variety frequent the Arctic
and Scandinavian seas, at depths of from 10 to 160
fathoms. Gould has recorded this species from Massa-
chusetts, and observed that he could find no difference
between the American shell and a specimen of L. minuta
from Norway, which had been sent to him by Dr. Loven.
Specimens vary very much in convexity
gree of striation. Those obtained from deep
and the de-
water are
usually flatter, and more delicately grooved, while specimens
from comparatively shallow water are more or
less tumid, and have stronger ribs. The flat and fine-
ribbed form has been taken by Dr. Torell at Spitz-
bergen. The fry have no ribs, but the cross lines are
very conspicuous.
Loven has not given any reason why he considers the
Area minuta of Montagu is not that of Fabricius, and
this eminent conchologist has strangely omitted the
authority of O. F. Miiller for that name. Three vears
after the publication of his *
Prodromus to the '
Zoo-
logia Danica/ Miiller described L. pernula ; so that he
was evidently aware of the difference between the two
species. Both are found living side by
side in the north-
ern seas. L. pernula is the Nucula oblonga of Brown,
which is not uncommon in the Clyde beds ;
and Stimp-
son has enumerated it among the pleistocene fossils lately
collected by Mri Drexler in Hudson's Bay. It may be
identical with the A r . cuspidata of Philippi, from the