116 M. E. lliickcl o/i the Oryaaizutloii of Sponges^ 



the stomacluil cavity aiul each ])erij^astiic radial chamber. 

 Thus the '''' jierson " of Cyathiseus dicides into a radial systein 

 of antiniera, JiiKt like each dcvelojyed coral-person. 



That the formation of antiinera occurs frequently in the 

 sponges generally, and that thereby a still closer approxima- 

 tion to the corals is ejected, has hitherto been entirely over- 

 looked, ^liklucho having only last year called attention to it 

 {I.e. p. 230). In Aj'inella j}ol//j>oideSj Osculina j>oli/stomella, 

 and many other sponges — among fossil forms, csj)eeially in 

 Ccelopf^chiuiH lohatain^ Siplionia costata^ &c., they strike one 

 at once. These '' radial " sponges are true " lladiata" no less 

 than most corals. It is evident, however, that, from a tecto- 

 logical point of view, the sponges in which antimora are so 

 distinctly ditlerentiated rise no less than the more highly deve- 

 lo})ed corals above the lower sponges, in whicli no formation 

 of antimcra occurs. 



Consequently, except the higher degree of histological dif- 

 ferentiation in most corals, there remains not a single character 

 which completely separates the sponges from the corals. Even 

 the tentacles surrounding the mouth, which have hitherto 

 appeared to be the exclusive property of the corals, begin their 

 development in certain sponges. At least I would regard as 

 {ncijnent tentacles the extremely remarkable curled and fringed 

 '' papilla; " which form a circlet surrounding the mouth-open- 

 ing of Osculina polystomellaj one of the most remarkable of 

 sponges. Moreover less importance is to be ascribed to the 

 tentacles of the corals, as secondarily developed appendages, 

 because even corals occur in which they are almost wanting 

 or developed only in the form of rudimentary buttons (e. g. 

 Antipathes). 



That the conditions of stock format ion or cormogeny are 

 exactly the same in the corals and in the sponges scarcely 

 needs to be particularly mentioned. It is precisely in this 

 respect that the agreement between the two classes is so 

 striking that it was this principally Avhich led the older natu- 

 ralists to unite the sponges and corals in their classifications. 

 \n the sponges we find no less multi^jlieity than in the corals in 

 the combination of the '' persons "to form stocks ; and even the 

 special modifications in the stock-formation which are produced 

 by the multifarious forms of inconq)lete division and gemmation 

 in the corals are reproduced in the sponges. Only one peculia- 

 rity pertaining here may be specially indicated, because it has 

 repeatedly led to singular misinterpretations. This is the 

 formation of peculiarly reduced stocks l)y the growing together 

 or concrescence (f the branches, i. e. ^^ persons." Just as in the 

 well-known fan-corals (e. g. lihipidogorgia flahellum) the pe- 



