Page:The common shells of the sea-shore (IA commonshellsofse00wood 0).pdf/39



pretty little shell, which is represented of its natural size on Plate II., fig. 3, is rightly severed from the Basket-shells, on account not only of its shape, but of the character of the shell. It is much flatter than the Basket-shells, although, like them, it has one valve longer and deeper than the other, and overlapping it at the edges. A glance at the shell will, however, detect one of the chief points of difference. The surface is shining and polished, and has a nacreous aspect, like that of the pearl oyster; this appearance being due to the manner in which the particles of the shell are arranged. On account of this peculiarity, the shells belonging to this genus are