BY R. VON LENDENFELD, PH.D. 347 



of the plant-like colony, and sometimes also forms cup shaped 

 extensions around the Trophosoms. The structure of the 

 generative zooids seems to me of a much more important nature. 

 I combine in this Suborder some Calyptoblastea, some Gyinno- 

 blastea, and Allman's Eleutheroblastea, I do not doubt that 

 everyone will agree with me, that this Suborder Hydropolypinae 

 is perfectly natural. - The difficulty lies, as pointed out above, in 

 the uncertainty of the origin of the Blastostyles. It is clear that 

 the Hydromedusa?, which are descended from species with free 

 swimming Medusae, are fundamentally different from those which 

 possess Blastostyles, which are not homologous to Medusa?, but 

 must be considered as Polypostyles. 



But the question whether a given Blastostyl is medusoid or not 

 can only be decided by careful histological researches, such as 

 those recently published by Weismann. (1) 



This author found moi'phological peculiarities in many Hydro- 

 medusse, which show that their Blastostyles are doubtlessly 

 Medusoid. In others again the evidence is not so clear, and in 

 many the careful investigator has not been able to detect any 

 trace in the morphology of the Gonophor, which would point to a 

 Medusoid origin. 



All the Genera enumerated under the Hydropolypinae, with the 

 exception of Hydra, would according to Weismann (I.e.) have to 

 be placed under the Hydroniedusime. The main features of our 

 classification would of course not be affected by this, only that some 

 of the Families placed here would then appear there. I think it 

 highly probable, that some of the Genera placed in this Suborder 

 will subsequently have to be placed in the second Suborder. 



1. FAMILY HYDRID^E. Claus, 1876. 



Solitary Polyps, which mature the sexual products in the 

 Gastral wall. 



The budding or fission (Protohydra), with which the Hydrida? 

 are propagated non-sexually is perfectly similar to and analogous 



(1. ) A. Weismann. Ueber den Urspruny der Geschhchts Zellen bei den 

 Hydroiden, 18S3. 



