[35/6]

I have seen two carinae in the collections of Mr Morris and Mr J . Sowerby so exactly like each other, and having a somewhat different aspect from S. maximum, var. sulcatum, to which they come nearest, that they deserve to be described, whether or not they are really specifically distinct. I long hesitated whether to give them a specific name, and have been, in some degree, influenced in doing so, from the presence of scuta and terga in the lower chalk, which indicate a distinct but closely-allied species. The scutum is in Mr Morris’s collection, and came in the same lot with the carina from Sussex: the tergum / is in Mr Bowerbank’s collection from the lower chalk of Maidstone. These valves are marked with longitudinal raised striae more plainly than is the carina.