A considerable part of the material forming the present communication was collected as long ago as 1862, but the specimens obtained at that time, with the notes thereon, remained in abeyance until quite recently. On a renewed examination of them, it appeared that much of what had been noted down had not been superseded, and this induced me to go through the whole of it again, and make such additions and modifications as seemed necessary to bring it into its present form. And I have done this in the hope, and indeed in the belief, that it will serve a twofold purpose. It will make known some forms which are new, not only to the particular locality, but also to the catalogue of English species; and it will furnish a more complete list than has yet appeared of the species from one of the best-known Coral-reefs of the Inferior Oolite.