io6 CORALS 



twigs. In some forms the branching takes place in all 

 directions, forming bushy or tree-like structures, but more 

 commonly the branching is in one plane only, so that the 

 structure is fan-shaped or flabelliform. 



The presence of the horny substance in the axis of the 

 Gorgonians is of advantage to them in man}/ sea localities 

 where the tides and currents are particularly strong, in that 

 it gives them the power to bend without breaking, the 

 calcareous skeleton of the purely calcareous Alcyonaria 

 being quite inflexible. In the tropical seas it is a wonderful 

 sight to see through a few feet of the clear water the great 

 tufts of brightly coloured Gorgonians attached to the piles 

 of a pier, or in favourable situations on the reef waving 

 backwards and forwards with the rise and fall of the water. 

 An intelligent observer seeing them for the first time would 

 probably be inclined to classify them with the other corals 

 of the neighbourhood, but would notice that they differ 

 from them in their flexibility. 



The Gorgonians, however, are not the only coral-like organ- 

 isms that are flexible, and the famous work by Lamouroux 

 published in 1816, entitled Poly piers coralligenes flexihles, 

 included Algae, Polyzoa, Hydrozoa, as well as some of the 

 Anthozoan corals. Nevertheless the popular expression 

 " flexible corals " has become more restricted, and is still 

 sometimes used to signify only the Alcyonarian corals with a 

 horny flexible axis. 



In the course of the descriptions that are given of 

 different kinds of Alcyonarian corals reference will be made 

 to their colours. These colours are, as a rule, due to a pig- 

 ment in the calcareous spicules which is permanent, that is 

 to sav, it does not fade or disappear when the coral is dried. 

 The permanence of these colours is really remarkable, as is 

 exemplified by the colour of the red coral beads in the 

 ancient British shield found in Lincolnshire (see p. 241), 

 which is probably as bright now as it was several hundreds 

 of vears before the Christian era, when the coral was dredged 

 up from the sea. The Alcyonarian polyps when fully ex- 

 panded in the seas are usually either transparently white 

 or of a faint pale pink colour, and when they are retracted 



