52 



R. T. Günther 



the Cladonemidae. The semi-pinnate , enidophor-bearing tentacles, 

 the streaks of nematocysts and perhaps too the in-pushing in the 

 eentre of the exnmbrella, if it be the vestige of a Scheitelhöhle, are 

 all featnres familiär among Cladonemid genera. 



But vrhen we endearour to more nearly define the relationships 

 of M/ttsfra to the other genera of Cladonemidae we are met with 

 diffieulties which will only be removed when the resnlts of a more 

 searehing investigation than has hitherto been made. of those other 

 genera is betöre ns. Then and not before wiU it be possible to 

 write the phylogenetie historv of the gronp with some pretence of 

 aecuraey. 



All schemes for the Classification of the Cladonemidae 

 which have hitherto been proposed seem to me to hare diffieulties 

 of their own. The reason for this is that within the limits of the 

 group several quite pecnliar organs have originated. organs which 

 are not known in any other gronp of Anthomedusae. We have 

 to deal with genera which differ very considerably in the grade 

 of their Organisation, and we have to take into account organs 

 which may be phylogenetieally related, or may have had an inde- 

 pendant origin among aUied organisms of which the chiefest mark 

 of kinship is that they have a tendency to develop in certain 

 ways. 



A few of the chief facts with which the systematic zoologist is 

 confronted and which he has to take into accotint in his Classification 

 are snmmarised in the following table. 



1 I adopt Hartlaub's nnmber instead of the 4 of Haeckel. 



