Anthozoa 



Hexacorallia . 

 Octocorallia. . 



Dodecacorallia 



Antipatharia 



Ceriantharia 



Zoophytaria 



Zoantharia 



Actiniaria 



Madreporaria 



In this, again, there is a closer association of the Antipatharia and Ceriantharia than 

 seems advisable, nor should the Madreporaria be separated as distinctly from the Actiniaria as 

 are the Zoantharia. Exception may also be taken to the nomenclature employed in both this 

 and van Beneden's classification, on the ground that in the latter the terminations adopted do 

 not sufficiently differentiate subgroups from groups, while in the former the term Hexacorallia 

 is apt to be misleading both on account of its form and on account of the different sense in 

 which hexamerism has been understood. 



I would suggest an arrangement and nomenclature somewhat as follows, as representing 

 fairly accurately our present information as to the affinities of the various groups. 



Alcyonaria 



Antipatharia 

 Ceriantharia 



Anthozoa. 



Zoanthactiniaria 



Hexactiniae. 

 Zoantheae 



Rugosae 



Madreporacea 

 Actiniacea 



This is essentially the classification I proposed in my paper on the Phylogeny of the 

 Actinozoa (1891), except that the Edwardsiae are now included in the Hexactiniae and the 

 Zoantheae and Rugosae are brought into closer relationship to the same group. This is in 

 accordance with the views I have held as to the significance of the development of the mesen- 

 teries in the different groups. It seems quite certain, both from the comparative study of adult 

 forms and from the embryological development, that a condition with eight mesenteries, developed 

 in couples, is well marked in all the Anthozoan groups with the possible exception of the 

 Antipatharia. Whether these are to be regarded as possessing only six mesenteries, comparable 

 to the eight of the other groups, or whether they are to be regarded as modifications from a 

 primarily eight mesenteried stage remains for demonstration, as does also the question of the 

 significance of all the additional mesenteries occurring in such a form as Leiopathes. In the 

 Alcyonaria the primary eight mesenteries are the only ones present, but in the Ceriantharia 

 and Zoanthactiniaria additional mesenteries are added. In the former group these are always 

 developed in couples, and this is also the case with the four mesenteries which succeed the 



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