From the close analogy of the fossil corals to existing forms, it would not be difficult to give restored figures of the originals. Every little branch might be represented fraught with living polypes: in some cells the agile inmates might be shown with the mouth expanded, and the tentacula in rapid motion; in others withdrawn into their stony recesses, and devouring the infinitesimal atoms that constitute their food: even their varied hues might be introduced, and thus a vivid picture be presented of the microscopic beings which peopled the waters of the ancient chalk ocean. That the Corals, which from their elegance and beauty are preserved in almost every cabinet, have been fabricated--or, in other words, built up--by polypes, in the same manner as the honey-comb of the bee and wasp, is so prevalent yet erroneous an opinion, that I am induced to point out its fallacy, by giving a brief account of the formation of these substances. The three recent specimens represented in _Lign. 27_ will serve to illustrate my remarks. [Illustration: Lign. 27:--Recent Corals. 1. _Oculina ramea._ 2. _Madrepora muricata._ 3. _Isis hippuris._ ] The coral, _fig. 1_, was an internal axis or skeleton, deposited by the soft fleshy integument with which, when living, it was wholly invested; in the same manner as are the bones of animals, by the special membrane (_periosteum_) that secretes them. This integument lined every cell, and the polypes were permanently united to it. When the live coral is taken out of the water, the animalcules shrink up and quickly perish; their soft parts and the external investing substance putrefy, and the stony axis beset with the radiated cells alone remains. [Sidenote: RECENT CORALS.] In the example of _Oculina ramea_, or May-blossom Coral, _fig. 1_, from the Mediterranean, the cells are large and distinct; in the _Madrepore_ from the West Indies, _fig. 2_, they are small and very closely aggregated. The specimen of _Isis_ (_fig. 3_) belongs to a group of coral-zoophytes in which the polype-cells consist of a substance that is durable, but not so hard as coral, and invests an axis composed of a tough flexible material, which is exposed at the base of _fig 3_, by the removal of the external or cortical part in which the polypes were situated. The _Gorgonia_, or Venus's fan, has a similar structure and composition.[AS] [AS] See '_Wonders of Geology_,' vol. ii. p. 616.