Shell very strong, nearly spherical, heart-shaped, concentrically striated, equivalve, smooth, with a dark reddish-brown epidermis; beaks very prominent and curled; two primary teeth in the right valve, lying parallel to each other; in the left valve the outer tooth is indented and is large, the other, thin and laminar. The lateral tooth strong and elongated, situated under the ligament, which is external.
This magnificent mollusk is very partially distributed, though plentiful in some places. Specimens have been sent to me from Dublin Bay, where, I grieve to say, they are getting very scarce, and also from Brixham, where they are highly prized by the fishermen. They do not, however, often bring them on shore, though they bring them up in the dredges, unless they wish to make a present of a dish to some friend, or know where they can dispose of them. They call them "Torbay-noses," and they are also known by the names of "Oxhorn-cockles," and "Heart-shells;" in France, Coeur de boeuf; in Holland, Zots-Kappen, or fool's cap; at Naples, Cocciola zigga; and at Venice, Bibaronde mare, and Ohama a cuore. Dr. J. G. Jeffreys, quoting an interesting account of Isocardia cor, by the Rev. James Bulwer (who kept a specimen in a vessel of sea-water, and was therefore able to study the habits of the animal), given in the 'Zoological Journal,' states, "that the animal appears insensible both to sound and light, as the presence or absence of either did not interrupt its movements; but its sense of feeling appeared to be very delicate; minute substances being dropped into the orifice of the mantle instantly excited the animal, and a column of water strongly directed, expelled them from the shell. With so much strength was the water in some instances ejected that it rose above the surface of three inches of superincumbent fluid .... Locomotion very confined; it is capable, with the assistance of its foot, which it uses in the same manner (but in a much more limited degree) as the Gardiacea, of fixing itself firmly in the sand, generally choosing to have the umbones covered by it, and the orifices of the tubes of the mantle nearly perpendicular.* Resting in this position on the margin of a sand-bank of which the surrounding soil is mud, at too great a depth to be disturbed by storms, the Isocardia of our Irish Sea patiently collects its food from the surrounding element, assisted in its choice by the current it is capable of creating by the alternate opening and closing of its valves".
* 'Common Sense in the Household,' by Marion Harland. † 'Recherches sur la Faune Malacologique de la baie de Suez.' 'Journal de Couch.' tome xiii. 1865.
* 'British Conchology, vol. ii. pp. 300, 301.
Isocardia Cor._Heart shell or Oxhorn Cockle.
del.G.B.Sowerby,lith. Vincent Brooks, Imp.
The Mediterranean species of this bivalve are smaller than those found on our coasts, and there are no less than five or six kinds known in the European and Indian seas.*
Epimarchus, in his play of the 'Marriage of Hebe,' mentions shellfish of all kinds, and says, -
"And bring too the black Cockle, which keeps the cockle-hunter on the stretch".†.
This may possibly refer to the oxhorn-cockle.
The wife of a coastguardsman, who had lived many years at Brixham, and had often luxuriated in a dish of these delicious shellfish, gave me the following recipe for cooking them : -
Wash the shells well, then boil them till they open - about ten minutes or so; take the fish out of the shells and put them into a frying-pan with some butter, a little salt and pepper, and fry till they are of a good brown colour; then serve.