- [Footnote: parts of which the whole consists forming a number of
organically distinct individuals. In the group of Phytocorals these individuals cannot detach themselves at pleasure, but remain united with each other by thin plates of carbonate of lime. It is not, therefore, by any means the case that each trunk of coral has a central point of common vitality or life. (See Ehrenberg's Memoir above referred to, S. 419.) The propagation of coral-animals takes place, in the one order, by eggs or by spontaneous division; and in the other order, by the formation of buds. It is the latter mode of propagation which, in the development of individuals, is the most rich in variety of form.
Coral-reefs, (according to the definition of Dioscorides, sea-plants, a forest of stone-trees, Lithodendra), are of three kinds;—coast reefs, called by the English "shore or fringing reefs," which are immediately connected with the coasts of continents or islands, as almost all the coral banks of the Red Sea seen during an eighteen months' examination by Ehrenberg and Hemprich;—"barrier-reefs," "encircling-reefs," as the great Australian barrier-reef on the north-east coast of New Holland, extending from Sandy Cape to the dreaded Torres Strait; and as the encircling-reefs surrounding the islands of Vanikoro (between the Santa Cruz group and the New Hebrides) and Poupynete (one of the Carolinas;—and lastly, coral banks enclosing lagoons, forming "Atolls" or "Lagoon-islands." This highly natural division and nomenclature have been introduced by Charles Darwin, and are intimately connected with the explanation which that ingenious and]*
