REPORT ON THE ANTIPATHARIA. 215 



cilia and are to be regarded as organs of circulation. They are formed from the 

 ectoderm by a downward growth of the stornodaaum. They are the last to be developed 

 in the oozooid, but the first in the blastozooid. The remaining six mesenterial filaments 

 are all derived from the entoderm, and have a digestive function. With regard to the 

 phylogeny of the mesenterial filaments, Wilson makes the following proposition : — 

 " I would suggest that it is in a high degree probable that the lateral lobes or ' Flimnier- 

 streifen ' of Actiniaria, at least in the principal or complete septa, are the homologues 

 of the ectodermic bands of Alcyonaria, and are likewise ectodermic downgrowths from 

 the stomodasum, and that the central lobes or ' Nesseldriisenstreifen ' are homologous 

 with the entodermic filaments. As the Hertwigs have described, if we follow the 

 filament upwards towards the oesophagus, the central lobe disappears and only the 

 lateral lobes remain. The filament is then closely similar to the dorsal filaments of 

 Alcyonaria, which are also bilobed. If we follow the filament downwards, the lateral 

 lobes disappear and the middle lobe remains. The filament is then essentially 

 similar to the entodermic filaments of Alcyonaria" (Mitth. Zool. Stat. Neap., Bd. v. 

 p. 21). 1 



Wilson also states, on the authority of Andres, that there is a certain amount of 

 embryological evidence in favour of the view that the upper part of the filaments of the 

 six principal mesenteries is derived by a downgrowth from the ectoderm of the 

 stornodaaum. 



Fowler, in a paper on the structure of Madrepora, &c, discusses Wilson's view as 

 to the phylogeny of the Anthozoan mesenterial filaments as applied to the Madreporaria, 

 and adds : — -" I may here state that, so far as histological evidence from the adult is 

 valuable, it points, in all the Madreporaria that I have yet examined, distinctly in the 

 opposite direction. The central ' Nesseldriisenstreifen ' have precisely the same micro- 

 scopic appearance as the stornodaeal ectoderm ; while the ' Flimmerstreifen,' in the 

 unbroken gradation by which they pass into the entoderm and by their characteristic 

 staining, seem to be much more nearly connected with that layer than with the ectoderm, 

 and to exhibit an intermediate condition between the ordinary cubical or pavement cells 

 of the endoderm and the enormously lengthened cells of Madrepora durvillei" (Quart. 

 Jour. Micros. Sci., vol. xxvii. pp. 8, 9). This is practically a return to the views of von 

 Heider, as Fowler himself points out. 



In the Antipathinae the structural evidence on this subject appears to me to be almost, 

 if not quite, conclusive. There is no similarity whatever between the ectoderm and the 



1 In the final section of his paper, Wilson discusses the relation of the Anthozoa to the Enteroecela, and points out 

 that morphologically each polyp consists of an anterior and a posterior chamber, together with a variable number of 

 paired lateral chambers, and compares the adult condition in Anthozoa with developmental phases of Peripatus. His 

 conclusions are so closely in harmony with those advocated on pp. 57-59 of this Report, that I feel it only just to state 

 that my conclusions have been arrived at quite independently, and that I had not read Wilson's paper until the whole 

 of my Report, with the exception of these last few pages, was in type. 



