Pvn H,i I'UitlS

CARDIUM. 269
ance of being partially decussated ; the ribs are also striated
transversely, but less distinctly than the furrows ; the whole
surface is covered with frost-like microscopical markings : colour
yellowish with a reddish tinge : epidermis fibrous, only observable
near the margins, having been removed in other parts
by continual attrition : margins rounded on the anterior side,
and sloping with an oblique curve in front to the posterior side,
which is produced, much broader than the other side, truncate,
and exhibits a long and narrow but distinct gape extending from
the edge of the hinge-hue to the angle where it joins the ventral
margin : beaJcs almost touching each other ; umbones tumid :
ligament cylindrical and thick, resembling the chrysalis of a large
fly, prominent, reddish-brown : hinge-line obtusely angular :
hinge-plate folded back towards the beaks, occupying scarcely
one-third of the circumference : teeth, in the right valve two
erect cardinals, besides two laterals on the anterior and one on
the posterior side ;
in the left valve two similar cardinals, the
posterior of which is very much smaller than the other, besides
one lateral on each side ; all the lateral teeth are triangular
and pointed : inside rather glossy, fluted towards the front and
anterior margins, the concavities corresponding with the outside
ribs ; the under side of the furrows is flat :
pallia! scar broad
and entire : muscular scars about equal in breadth, but the
anterior one is the longer. L. 32. B. 3*35.
Habitat : Not uncommon on the South- Devon
coasts, especially at Paignton near Torbay, but scarcely
ever found in a living state ; Weymouth (Thompson) ;
Guernsey (Lukis) ; Dublin Bay (Brown) ; Point of
Ayre, Isle of Man (E. Forbes) ;
Hebrides and Orkneys
(Pennant). These last two localities, as well as the
next, are very doubtful. Mr. James Smith says, on the
authority of the late Dr. Landsborough,
that it occurs
in the glacial deposit at Stevenston. Sars has dredged
a fine specimen near Bergen ; De Gerville, Collard des
Cherres, and Mace have recorded the species as in-
habiting the North of France ;
and many
other authors
have described or enumerated it as Mediterranean. It
may
on the whole be considered a southern form.
Young specimens are globular and not angular ; and