4 CORALS 



It is a word, in fact, which has no longer any defined meaning 

 in zoological and botanical systematics, but signifies simply 

 a heterogeneous group of organisms or the products of 

 such organisms that have the common habit of living in 

 the sea and producing a shell structure of carbonate of lime. 



Such a definition, or rather attempt at a definition, is 

 incomplete without reference to some special cases. There 

 is a certain group of animals, known to the zoologists as 

 the Antipatharia, which produce a hard black axial structure 

 of keratin or horn, and the substance of this structure can 

 be polished and used in the same way as the Precious coral. 

 It was used by the ancient Greeks as an antidote {dvnirad^'}^) 

 to poison, it was called by many writers of the sixteenth 

 and seventeenth centuries the Coralliitm nigrum, and is 

 still called Black coral in the shops where it is sold. Some 

 reference to the Antipatharia, therefore, should be made 

 in any general account of Corals, although they do not 

 secrete any calcium carbonate and are not included in the 

 general definition of the word. 



The large subdivision of the Animal Kingdom called the 

 Mollusca, and also the Brachiopoda, include many forms 

 that are sedentary in habit and secrete shells of calcium 

 carbonate, but all of these must be excluded from the 

 definition, for I do not believe that the name Coral has ever 

 been applied to them by serious students of Natural History. 



A more difficult question to decide is whether to include 

 in a general treatise on Corals, the Alcyonaria with hard 

 axes of horny substance or with axes composed of both 

 horny and calcareous substance which have been known 

 for a long time under the general name of " Gorgonia." 

 There can be no doubt whatever as to their close zoological 

 relationship with the Precious coral, and one genus of them, 

 namely Isis, was known to Imperato as Corallium articu- 

 latum and to later writers as the " King Coral " or " Jointed 

 Coral." On the other hand, they are also closely related to 

 the soft and spongy Alcyoniums (Dead Men's Fingers) of our 

 own coasts and the Sarcophytums of the coral reefs which 

 were not usually given the name Coral by the older writers.^ 



1 See, however, Milne-Edwards on p. 6. 



