There is but one genus of the Coralline Gorgon, and the type of that is the common red ornamental coral of commerce found in the Mediterranean Sea only. Dr. Carpenter has discovered that the solid calcareous stem of the Corallium rubrum is made up of aggregations of spicules closely resembling those of the other Alcyonian zoophytes, but of an intense red, sometimes rose colour or whitish. The stem and branches are delicately striated along their length, and covered with a soft substance of the same colour as the stem, into which the polypes retreat when alarmed; but when fishing for food, with their eight white tentacles expanded, the red stem and branches appear as if they were studded with stars. Prof. de Lacaze Duthiers, who was appointed by the French Government to investigate the natural history of the red coral with a view to the regulation of the fishery at Algiers, found that the individual polypes are either male or female, but that the males and females are on different branches of the same coral, one branch being almost exclusively the abode of male polypes, and another of female. The eggs are fertilized by the intervention of the water. After an egg is fertilized, it is transferred to the stomach of the female, which thus serves both for digestion, incubation, and transformations of the egg. At first the egg is naked and spherical; afterwards it becomes elongated and covered with cilia. A cavity is formed in it, which opens externally, and finally becomes the mouth; it then acquires the form of a little white worm, and when it comes into the water it is very active, swimming in all directions, avoiding its comrades when they meet, rising and descending in the water with its hinder end foremost. It loses its cilia after a time, fixes itself to a rock, and acquires the form of its parent in the manner described as to other Gorgons. [Illustration: Fig. 126. Red Coral Branch.] The red coral generally grows on the under-side of ledges or rocks, in a pendent position, and at considerable depths. It is not found at 15 or 20 fathoms; they only begin to fish for it at from 30 to 60 fathoms; and it is brought up from even 100 or 120, while the strong reef-building corals cannot exist below 25, or at most 30 fathoms; being immensely superior in vigour, these require a greater supply of air, light, and heat. The red coral is generally fished for along the coasts of Algiers and Tunis; it is also found in the seas round Sicily and Sardinia, and in the Grecian Archipelago. The red coral is always irregularly branched. The branches are sometimes white, supposed to be from disease; the white coral of commerce is a species of Caryophyllia, an Actinian, and not an Alcyon, zoophyte. [Illustration: Fig. 127. Red Coral (greatly magnified), from ‘Histoire Naturelle du Corail,’ par M. Lacaze Duthiers.]