Pvn H,i I'UitlS

CRENELLA. 133
logy/ published in 1827, being the same year
which Mr. Berkeley's notice appeared in the f
Journal/ a circumstance that undoubtedly
as that in
Zoological
must have
some weight with a scientific jury ; but after consider-
ing the whole case, and taking into account the positive
disadvantage which would result from a change of any
name that has been generally recognized, I must give
my verdict in favour of Mr. Berkeley. This species is
the Modiola asperula of Searles Wood's Catalogue of
Crag fossils.
2. C. decussa'ta*, Montagu.
Mytilus decussaftis, Mont. Test. Brit. Suppl. p. 69. C. decussahis, F. & H.
ii. p. 210, pi.
xlv. f. 2.
Body greyish-white : mantle quite open in front, and folded
at the posterior or broader end of the shell to form an excre-
tory tube ; edges fringed with very short and minute glistening
cilia, which correspond with the ribs of the shell : tube very
short and sessile, with a plain margin : foot worm-shaped, consisting
of a long stalk with a sheath at the end, from which
proceeds an oval creeping- disk.
Shell obliquely oval, with a slight approach to a rhomboidal
form when viewed sideways, rather solid, somewhat glossy and
prismatic : sculpture, 50-60 fine longitudinal ribs, crossed by
40-50 transverse striae ; the former resemble those of the last
the latter are thread-like and form minute nodules or
species ;
beads on the ribs at the points of intersection : colour pearlwhite
: epidermis rather thick and yellowish-brown : margins
rounded on all sides except at the back, where an obtuse
angle separates the hinge-line : beaks globular and prominent,
placed close to the anterior margin, over which they slightly
project; they are quite smooth, with the exception of some
delicate transverse striae : ligament thick, reddish-brown :
hinge-plate rather broad, finely cre-
hinge-line nearly straight :
nulated : hinge toothed as in the last species : inside nacreous,
showing more or less distinctly the impression of the ribs ;
inner margin notched all round : scars more perceptible than
* Divided crosswise.