54 i^- '^- Giiuther 



Klciithvria. A more logicai procedure would bave been to liave 

 estahlished a iiew position for the curious creeping- Eleutheria and 

 to have abstained from attributing- to free-swimming genera an 

 organ the existence of which in the sense of Hartlaub, has never 

 been deinonstrated and of wliich the originai describer has giveu 

 a totally differeut Interpretation. 



Tentacles of the Cladonemidae. 



Since in the Classification of the Cladonemidae, about to be 

 jìroposed, the structure of the tentacles is uiade a primary basis, 

 a few remarks upon their structure may not be out of place. Two 

 types are recognised, the semipinnate and the arbore scent or 

 branching. Mnestra affords us an example of the semipinnate 

 tentaclo with cnidophors ranged ali along the abaxial side; similar 

 tentacles occur in PteroHona, Zanclea^ Geiìimaria and Ctcìiaria, save 

 only that in the last mentioned genus the cnidophors are filiform 

 instead of being club-shaped. 



The branching tentacle in its sim]»lest forni occurs in Eleuilieria. 

 The tentacle is divided into axial and abaxial branches, of which 

 the abaxial brauch ends in a capitulum of thread-cells, but the axial 

 brandi in the younger stages [Clavatella] ends in a sucker, which 

 is stateci to be sometimes replaced by a capitulum of thread-cells in 

 old individuai of Eleutheria. In Cladonema and Dendronema botli 

 the axial (sucker) brauch and the abaxial (thread-cell-bearing) brauch 

 bear many socondary branches or ramuli. The branching is ofteu 

 of a dichotomous type. The abaxial branchlets mostly end in ca- 

 jiitula of thread-cells and they are armed with little thread-cell bat- 

 terie« at intervals along their length. The abaxial portion of the 

 tentacle is in fact very like a branching tentacle of the polyp Cla- 

 docoryne which is also provided with numerous "capitate ramuli", 

 or like the circumoral tentacles of the Margelidae. One of the 

 first questions which occurs to the morjihologist is: can it be shown 

 that eitiier the semipinnate or tlie branching type of tentacle is derived 

 from the other, or that they are of inde})endent origin? 



I believed at first that it might be denionstrable that cnidophors 

 borne on the scniipiuuate tentacles might really be much reduccd 

 tentacular ìiranches each armed with its little terminal capitulum 

 of threadcells, and that consequently the semipinnate tyjie should 

 be regarded as the derivative of the arborescent type. Pnrther 



