56 1^- T. Günther 



cyst-coiitaiuiug structure, hcre eallcd a nematocyst tube. Allman 

 desci'ibed 1 such iu Gemmaria as "piriform Chambers" exteuding' 

 from the circular caual aud fillcd with small oval threadcells 

 wliicli cau havc nothing- to do with the capture of prey, being 

 sinik beueath the surface of the body. In CteHaria there seem to 

 he 2 8uch uematocyst tubes, aud in Willia Forbes 24 small short 

 sacs of similar nature. 



Until we have definite Information to the contrary it is safer, 

 judging from the aj)pearance of the uematocyst tubes, to regard 

 them as coecal endodermal outgrowths of the circular caual and 

 as haviug no homological relation to the ectodermal streaks upon 

 the exumbrella of finestra and Zanclea. Öeveral cases in which 

 nematocysts have developed from endoderm have already been de- 

 scribed and so there is no a priori difficulty about that. 



When we examine the Classification proposed by Haetlaub in 

 fiirthcr detail, we find that not only are Ctenaria and Gemmaria 

 separated as iu the Haeckelian system, but that Pteronenia is alien- 

 ated from Zanclea and Gemmaria, and Bendronema from Clado- 

 neina: i. e. it must be hypothecated that tentacular structures of 

 identica! nature have l)een independently evolved in two separate 

 subfamilies. It is easier to believe that the nature of the "Scheitel- 

 höhle" in Haeckel's genera is not quite what Hartlaub has assu- 

 med it to be. 



I believe that the following scheme of Classification will be 

 found to be more iu accordance with the Statements which have 

 been made conceruiiig many poiuts iu the anatomy of Cladonemid 

 mcdusae and will show clearly what is believed to be the relation 

 of ybicstra to the other genera. It must however be clearly stated 

 that no expression of opinion is intended in the scheme as to the 

 homology or lack of homology between the Scheitelhöhle of Eleu- 

 therki and of other genera and the exumbral iu-pushiug in Mnestra. 



Order Anthomedusae. 



Family Cladonemidae Gegenbaur. 



Anthomedusae witli tentacles armed with cnidophors, or brauchcd. Radial 

 canals 4 — S in ntimljer, simple or forked. Mouth either simple or provided 

 with oral lips or oral tentacles (the sessile Mnestra excepted). Genital ridgos 

 4( — 8), separate, upon the manubrium. Brood cavity, when developed, above 

 the Btomach. 



