Fig. 143. Cytherea geographica (Chemnitz).
Among the vast number of species, many of them are extremely rare, and much sought after by collectors in consequence of their great beauty. In the principal ports of France, Venus verrucosa (Fig. 142), and another species known in the south of France under the name of Clovisse, are eaten there like oysters. Prepared with fine herbs, the Clovisse, we have M. Figuier's authority for saying, is not to be despised. "We may be believed also," he says, "if we add that nothing is more delicious than to eat the living Clovisse torn from the rock of the Phara of Lake Thau, when the Mediterranean sun of a day in winter is shining down upon us, the heart rejoicing in manhood's strength." In Pl. XVIII. some of the principal species are represented, along with some of the more remarkable species of Cytherea. In Fig. 143 we have the elegantly pencilled shell of Cytherea geographica, together with the animal in its natural connection.
The sub-section we shall now treat of is without the pallial line sinuated. The Cyprinidæ form the ninth family of our arrangement of the Conchifera, and contain, Cardia, Cypricardia, Isocardia, Crassatella, Astarte, Circe, and Cyprina, which amount together to some hundred species.
The Cycladidæ are our tenth family, and include Cyrenoides, Cyrena, Pisidium, and Cyclas.
The Lucinidæ is the eleventh family, containing Galeomma, Lepton, Montacuta, Kelia, Diplodonta, Corbis, and Lucina.
In the small family of which we have made the Tridacna the representative, as well as in some preceding families, the mantle of the animal is more or less largely open, but never with such a prolongation as to form tubes. In the Cardiums, now under consideration, as well as Donax, Tellina, and Venus, the respiratory organs are somewhat modified, so as to adapt them to the habits of the animal. All these molluscs live buried in the mud or sand, and two great tubes issuing from the interior of their bodies bring the atmospheric air into communication with their respiratory organ—namely, the branchial leaves.
The twelfth family, Cardiadæ, contains the familiar cockles—Cardium—which is derived from καρδὶα, a heart, which they are supposed to resemble in form, are amongst the most widely-distributed of shells. The shell is convex, as we see in C. hians (Fig. 144), somewhat heart-shaped, equivalved, the edges dentate or corrugated, the hinge furnished with four teeth upon each valve. The accessary ornaments vary with the species, some being smooth, as in Cardium Greenlandicum, Chemnitz (Fig. 145); others, and by far the greater number, are furnished with regular sides, generally obtuse, sometimes in ridges diverging from the point and armed with straight or curved spines, arranged in the oddest manner, as in Cardium aculeatum (Fig. 146).
Plate XVIII.—Venus and Cytherea.