CORALS AND SEA-ANEMONES 389 



•coral-zone of the Red Sea and the Indian and Pacific Oceans ; but the West 

 Indian coral-fauna has a distinct character of its own. As a rule, the higher the 

 minimum temperature of the sea, the more abundant and luxuriant do corals become ; 

 the richest coral-fauna in the world being that of the seas around the Fiji Islands. 



Corals, together with their near relatives sea-anemones, are members of the 

 •class Anthozoa, or Actinozoa ; the more typical group, which includes the reef- 

 building species, as well as sea-anemones, constituting the suborder Zoantharia 

 in which the polyps and their supporting cups are usually constructed on multiples 

 •of a six-rayed type, as may be verified by counting the number of vertical 

 pai-titions in a mushroom-coral. Single, non-massive corals often attain very 

 considerable dimensions, specimens of the mushroom-coral (Fungia patella), for 

 •example, not infrequently measuring as much as eight inches across the disc and 

 half as much in height. Compound colonies of the massive corals, such as some of 

 those shown in the illustration on page 367 of the great barrier-reef of Australia, 

 grow, of course, to much larger size, an example of Turbinaria peliata in the 

 British Museum measuring 16J feet in basal circumference and weighing just 

 over 13^ cwt. 



The brilliantly coloured and delicately made sea-fans or bark-corals of the 

 genus Gorgonia and its relatives, together with the sea-pens (Pennatula, etc.), in 

 which the skeleton is much reduced, belong to a group, the Alcyonaria, in which 

 the vertical divisions in the cups for the polyps are eight in number, as are also the 

 tentacles of the polyps themselves ; such tentacles, moreover, having fringed or 

 pinnate tips, instead of the simple summits of the numerous tentacles of the reef- 

 building corals and the sea-anemones. Many of these alc3 7 onarians form con- 

 spicuous features of coral-reefs. To this division belong the massive blue coral 

 (Heliopora cazrulea) of the Pacific, a species of particular interest as being the 

 survivor of a type abundant during the Palaeozoic epoch; the well-known red 

 organ-pipe coral {Tubipora musica), in which the individual polyps live in 

 separate tubes connected together by horizontal platforms ; and the precious red 

 coral (Corallium rubrum), the species to which the name coral appears properly 

 to belong. A remarkably handsome representative of the organ-pipe corals is 

 Tubipora hemprichi, of the Red Sea and Indian Ocean, in which the tubes are 

 rich purple. Corals may in fact be of many colours, ranging from white or pure 

 yellow to the full red-pink of the precious coral and the deep polished ebony- 

 black of the large branching stems of the tree-like species known as Gerardia 

 savalia, in which the branches interlace and unite with one another to form a 

 network. Despite the horny nature and peculiar form of its skeleton, this 

 splendid species should apparently be classed with the reef-building forms in the 

 zoantharian section. 



Although some mention has previously been made of the precious red coral 

 of the Mediterranean and adjacent parts of the Atlantic, it may be well to observe 

 that the genus Corallium is represented by other species in the seas of Japan, 

 Mauritius, and Madeira. Mediterranean red coral was well known to the Romans, 

 and about the beginning of the Christian era was exported in such large quantities 

 io India that it was difficult to obtain in the countries where it was produced. 

 'The great bulk of the coral is sold at Messina, Naples, Genoa, Leghorn, and 



