BY DR. R. VON LENDENFELD. 211 



out in that paper, that many of the statements contained in this 

 first attempt of the kind, are erroneous. Since then a work (1) on 

 the generative elements of the Hydromedusse, has appeared which 

 is equally excellent for the correctness of the observations con- 

 tained therein as for the ingenious conclusions drawn therefrom. 

 Although I did not receive this work until after this paper had 

 been read before the Linnean Society of N. S. Wales, I shall still 

 endeavour to make as much use of it as as possible. 



The observations contained in this book are given in a table 

 (I.e. p. 214, f.f.), and show, that many of the genera which I had 

 placed in my former (I.e.) paper, among the Hydropolypina?, show 

 in the Gonophores no traces of a medusoid structure. There are a 

 few however, in the Gonophores of which such traces have been 

 discovered by Weismann ; genera which I had placed under the 

 Hydropolypinae. These are Sertularia and Plumularia. 



Weismann (I.e.), states that two genera, namely Autennularia 

 and Campanularia are peculiar, for the extraordinary difference 

 between the male and female Gonophores. In both these genera 

 the male Gonophores show no trace of the Medusoid structuie, 

 whilst such a structure — several layers of cells outside the gener- 

 tive elements — is met with in the female. 



Now of course it is quite out of the question to suppose, that 

 the ancestors of these two genera possessed female Medusae, whilst 

 the male Gonophores were always sessil Polypostyles. We must 

 therefore, conclude that both male and female Gonophores descended 

 from free Medusae or from sessile Polypostyles, Weismann 

 considers it probable — any such conclusion of course can only be 

 the more or less probable and never certain — that both descended 

 from free Medusas. Now the male, Dot Medusoid Gonaphores, of 

 these, are quite similar to those of other Hydroids, and so Weismann 

 concludes further, that also these (Aglaophenia Sertularella. 

 Opercularella) have descended from free Mudusae. 



(1.) A. Weismann. Die Entstehung der Sexnolzellen bei deu Hydro- 

 medusen. Jena, 1883. 



