Pvn H,i I'UitlS

SCROBICULARIA. 437
very short delicate and scattered minute flocculent marks, ap-
parently caused by an exfoliation of the epidermis
margin is more evenly curved and the ;
upper or dorsal margin
on the posterior side has the same curve and angle of incidence
as the lower posterior margin, both meeting halfway in
: the ventral
a rounded and upturned point ; the angle on this side is very
indistinct ; there is scarcely any depression below the beak on
the posterior side, the dorsal margin being more expanded :
the cartilage is golden-yellow and longer than in the other
species, and the pit is larger
and more twisted : the inside is
lineated lengthwise, but is also microscopically fretted like
shagreen : muscular scars conspicuous, the anterior being ob-
liquely elliptical and the posterior triangularly eval. L. 0*45.
B. 0-8.
Yar. ovata. Shell more oval, often eroded near the beaks.
Habitat : More local than S. prismatica, in muddy
100 fathoms : south coast of
sand, at from 3 to nearly
Cornwall (M 'Andrew); Dogger bank (Howse andMen-
nell) ; all the coasts of Ireland; west of Scotland; and
north and east of Shetland. The variety was taken by
Barlee and myself while dredging together in Birterbuy
writer on the Scandinavian
Bay, co. Galway. Every
mollusca has noticed its occurrence in those seas, at
depths varying from 6 to 110 fathoms. The only southern
locality recorded is Algeria, on the authority of
M. Weinkauff.
The animal is quite as lively as its congener ; but the
shell gapes (or, for the sake of the antithesis, I may say,
yawns)
much more.
It is the Amphidesma intermedia of Thompson. If
the recognition of the Mya nitida of Muller depended
on the very obscure diagnosis in his '
Prodromus/ I
should have felt the same disinclination as the authors
of the ' British Mollusca '
to accept the last-mentioned
specific name ; but an article by Fabricius,
volume of the l
in the fourth
Skrivter af Naturhistorie-Selskabet/