From the earliest times the Tridacna shells, on account, of their huge size, have attracted the notice of naturalists, so that, the pioneers of conchology more than a hundred years ago already had collected a large body of information about them. But modem zoologists have not found much more to add, perhaps because the subject was considered to be exhausted. Yet the history of the habits, affinities and nomenclature of this curious genus is still far from complete.
A Tridacna occurring abundantly in the Gulf of Suez was examined by Dr. Leon Vaillant. He determined it, probably erroneously, as Tridacna, elongata, Lamarck, and described it as buried in sand so that the serrate margin of the valves alone projected and as moored by a profuse byssus hawser to the stone beneath; he adds that the bivalve may change its position and even move to a distance. Vaillant concluded that all other members of the genus Tridacna have similar habits and disparages those writers and travellers whose observations differ from his own. Thus he doubted the accuracy of the account of the large, fleshy foot given independently by Quoy and Gaimard and by Woodward. In reference to the statement that T. crocea lives buried in coral, Vaillant supposes that it, could not actually excavate the stone and must therefore have been enveloped by an over growth of the living coral polyps. These views, advanced with so much authority, seemed to have gained general acceptance.
In Australia, Tridacnidae do not behave as Vaillant describes...