206 THE AUSTRALIAN HYDROMEDUS.E, 



THE AUSTRALIAN HYDROMEDUS^E. 

 By R. von Lendenfeld, Ph.D. 



Part L — The Classification of the Hydromedus^e. 



The Hydvomedusae are here taken in the sense, which Claus (1) 

 attaches to his order Hydroidea. They are characterized by 

 Claus (I.e.) in the following manner : — 



" Kleine Polypen nnd ramificierte, festsitzende Poly penstock e 

 mit inediisoiden Geschlechtsgemmen oder mit kleinen Medusen 

 als zugehorige Geschlechtsgeneration, sowie kleine mit Randsaum 

 versehene (craspedote) Medusen, ohne polypoide Ammengener- 

 ation." 



It must be noted, that all Hydroid Zoophytes, " whether they " 

 have Medusoide Geschlechtsgemmen "or" produce generative 

 elements without the aid of medusoid buds, are placed in the order 

 Hydroidea by Claus. The same course will be adopced in this 

 paper. 



Accordingly the Hydromedusas comprise the Hydroid Zoophytes 

 (Hincks), and the craspedote Medusen (Haeckel), together with 

 the Hydrocorallinse (Moseley.) 



Although, perhaps only few groups of animals have been the 

 subject of so many papers, as the Hydroruedusse, still our know- 

 ledge, particularly of the Australian representatives of this group, 

 is very limited. 



Most of the Hydromedusse undergo a change of generation, 

 which is very different in the different Families. The adult animal 

 with sexual products is in many cases a Medusa, and of course it 

 is this stage of the whole cycle of changing generations, which 

 must be considered most in describing, naming and classifying our 

 animals. 



(1.) C. Claus Grundziige der Zoologie vierte Auflage. Seite, 248. 



