Simpson — A Revision of the Gorgonellidae. 29 



With regard to the coenehchyina in these tlivee groups, the following 

 notes are interesting : — 



(1) In all of them there is a circle of large canals separating the 

 coenenchyma from the axis. 



(2) Near the periphery of the coenenchyma there is also a circle of 

 longitudinal canals which communicate directly with the polyps. 



(3j These two series are united by numerous interlacing transverse 

 solenia. 



The polyps are very similar in all three groups. There is no definite 

 distinction into verruca and anthocodia. There is a pseudo-operculum 

 formed of small spicules on the aboral surface of the tentacles in all three 

 groups. The polyps are in all cases capable of complete retraction into the 

 coenenchyma. 



A further point of similarity may be pointed out in the case of 

 Suberogorgia and Juncellids, namely, the possession of a definite number of 

 longitudinal canals in the inner series larger than the others, which deternune 

 the distribution of the polyps. 



It would be premature to draw any hard and fast conclusions from 

 these few observations ; but it may be consiilered a question wlielher the 

 •three groups taken in the following ordei-, (1) Suberogorgia, (2j DcndnKjorgia 

 capemis, and (3) the Juncellids proper, may not represent a line of 

 evolution. In the first of these the spicules of the axis are large, 

 and there is only a small amount of horny matrix ; in the second the 

 spicules are smaller, and there is a larger proportion of horny material ; 

 while in the last the spicules (if such is the nature of the calcareous matter) 

 are extremely small, and the proportion of horny substance to the calcareous 

 is enormou-sly increased. 



For the present, and until the exact nature of the limy deposition in the 

 axis of the Gorgonellidae is investigated, it is therefore inadvisable to rank 

 them with the Axifera, and it is more than probable that their affinities are 

 closer to the Pseudaxonia. 



VII.— Division of the Gorgonelliuae into Genera. 



Before proceeding to formulate a scheme of classification which may 

 approximate to a natural classification, and whieli will be based on the foregoing 

 considerations, it may be well here to recapitulate the most recent diagnosis 

 of the genera under consideration, and see to what extent each of these may 

 be considered valid. 



Juncdla. — Tlie colony is simple or branched, the polyps are sometimes 

 small, disposed in two lateral rows, sometimes with well developed and 



