The principal genera are:—_Melitodes_, Verrill; widely distributed in the Indian and Pacific Oceans, Cape of Good Hope, etc. This genus is in some localities extremely abundant and exhibits great brilliancy and variety of colour. The branching is usually dichotomous at the nodes. _Wrightella_, Gray. This is a delicate dwarf form from Mauritius and the coast of South Africa. _Parisis_, Verrill; Pacific Ocean from Formosa to Australia but not very common. One species from Mauritius. The branches arise from the internodes. {352}FAM. 4. CORALLIIDAE.—The axis is formed by the fusion of spicules into a dense, solid, inflexible, calcareous core. _Corallium_, Lamarck. _Corallium nobile_, Pallas, the "precious coral," occurs in the Mediterranean, chiefly off the coast of North Africa, but also on the coasts of Italy, Corsica, Sardinia, and it extends to the Cape Verde Islands in the Atlantic Ocean. _C. japonicum_, Kishinouye, called Akasango by the fishermen, occurs off the coast of Japan, and _C. reginae_, Hickson, has recently been described from deep water off the coast of Timor.[377] The genus _Pleurocorallium_, Gray, is regarded by some authors as distinct, but the characters that are supposed to distinguish it, namely, the presence of peculiar "opera-glass-shaped spicules," and the occurrence of the verrucae on one side of the branches only, are not very satisfactory. The following species are therefore placed by Kishinouye[378] in the genus _Corallium_:—_C. elatius_, Ridley (Momoirosango); _C. konojoi_, Kishinouye (Shirosango); _C. boshuensis_, K.; _C. sulcatum_, K.; _C. inutile_, K.; and _C. pusillum_, K.,—all from the coast of Japan. Of the coral obtained from these species, the best kinds of Momoirosango vary in price from £30 per pound downwards according to the quality. The Shirosango is the least valuable of the kinds that are brought into the market, and is rarely exported.[379] Three species of _Corallium_ (_Pleurocorallium_) have been described from Madeira,[380] and one of these, _C. johnsoni_, has recently been found in 388 fathoms off the coast of Ireland.[381] Other species are _C. stylasteroides_, from Mauritius; _C. confusum_, Moroff,[382] from Sagami Bay in Japan; and an undescribed species obtained by the "Siboga," off Djilolo. These corals range from shallow water to depths of 300-500 fathoms. _Pleurocoralloides_, Moroff, differs from the others in having very prominent verrucae and in the character of the large spindle-shaped and scale-like spicules. It was found in Sagami Bay, Japan. Specimens attributed to the genus _Pleurocorallium_ have been found fossil in the white chalk of France, but Corallium has been found only in the tertiaries.[383] {353}SUB-ORDER 2. AXIFERA.