187 
CARDIUM hibernicum. 
TAB, LXXXII.—Figs. 1 and 2. 
Spec. Cuar. Very broad and deep, longitudmally 
striated ; posterior side deeply truncated, bound- 
ed by a large circular ridge, concave, wth a 
nearly central umbo; anterior side elongated. 
Beaks incurved, small. 
— ee 
Tue length of this is nearly equal to the width, and the 
depth but little less than the length. The size and sharp- 
ness of the longitudinal ridge that bounds the concave poste- 
rior side, is such as to give the shell a carinated form; it 
arises from the beaks; the umbo in the centre of this side is 
a kind of wing. The striz on the surface are rather distant, 
and the spaces between them convex, but not enough sc to 
be called ribs. 
The Genus Cardium is so constant in its characters that 
it can seldom be mistaken; its species may generally be 
known by analogy, although the internal parts cannot be 
seen; the present one, however, without a knowledge or 
comparison with a recent species as unlike others of the 
Genus as itself, might have remained unintelligible, but 
with such an help we are enabled to be bold, and undoubt- 
ing: the Venus’s heart Cockle, Cardium cardissa, has the 
internal characters very decisive, and the remarkably curious 
external form is nearly the same as that of the stony cast, 
except that the sides or wings, if I may be allowed to call 
them so, are not so much elongated. It is with much plea- 
sure I thank my Friends, Dr. Wood and S. Wright, Esq. 
of Cork, for specimens from the black marble rock in that 
vicinity. Mr. J. Humphreys has materially assisted me 
with specimens, and I have had one from Mr. W. Moore 
of Cork, who considered it as the heart Cockle. They are 
provincially called Asses’ hoofs, and I am told they are 
sometimes so large as to answer to the appellation in respect 
of their size. The Cardium found in the neighbourhood of 
Paris, by Lamarcke, is quite distinct, and more like C. car- 
dissa, ours not having the denticulated edges: may their 
