142 CORALS 



The axis of Gerardia consists of a series of concentric 

 lamellae of black horny substance, but the lamellae appear 

 to be more firmly cemented together than is generally the 

 case in the Antipatharia. In the centre of the axis there is 

 usually found a core of a substance which is not formed by 

 the Gerardia. This may be the stem of a Gorgonian coral 

 or some other structure which the (ierardia has covered by 

 encrustation in the early stages of its growth. 



The surface of the axis is smooth to the touch, as it 

 does not possess the prickles or spines which form such a 

 characteristic feature of the axis of the branches of the 

 Antipatharia. But when the surface is examined with a 

 magnifying glass it is found to be covered with a number 

 of little pitted mounds {mamelons omhiliqiies)} 



So far as is known at present the genus Gerardia is 

 confined to the Mediterranean Sea. The large specimen in 

 the British Museum came from Grecian waters, but speci- 

 mens of great size are also obtained by the coral fishers on 

 the coast of Algeria and Tunis. 



1 According to de Lacaze-Duthiers, I.e. p. 216. 



