58 R- T. Güuther 



(CladcuoniHta) of the Pycnomerinthia or Oceanidac wliich have solid teiitacles 

 almust tìllod with laige endoderm cclls. My investigations on Mncstra, ITaeckel's 

 drawings of Gemmaria and Dcndronema and Allman's description of Clado- 

 nema prove tliat tliese forms at any rate possess tentacles of the Coelomerin- 

 thic type i.e. contractiie hollow teutacles with endodermal cells surrounding 

 tho lumen. On these and other grounds it would seem advisable to retain the 

 Cladonemidae iu a position of importance equal to that of the Codonidae and 

 Oceanidae, as a thiid family of Anthomedusae in the System of Vanhöffen. 



Conchisions. 



In conclusion, it is believed that Mnestra owes its peculiar structure partly 

 to the tendencies of growth which it has inherited froui past ancestors and 

 which it shares to a greater or lesser extent with other Cladoneiuldae, and partly 

 to its sessile habit of life. In the first category I would include: 



1. Such radial symmetry of parts as is disco verable in selected indi- 

 viduals. 



2. 4 hollow tentacles armed with stalked cnidophors, in a series along 

 tlie aboral luargin. 



3. 4 radial canals. 



4. 4 perradial cnidacts upon the exumbrella. 



5. A ring of cnidoblasts all round the margin of the umbrella. 



6. The in-pushing in the centre of the exumbrella. 



The characters supposed to be due to its sessile habit are: 



1. Asymmetry of form. 



2. Reduction of cnidophor-bearing tentacles from the primitive number (4). 

 .'5. Inegularitics in the development of gastric cavity, radial canals, cnidacts 



and exuiiibral in-pushing. 



4. Suctorial mouth. 



5. Suppression of swimming powers. 



6. The supposed migration of the germ cells into the body of the Phyllirho'é 

 where fertilisation and development are believed to take place. 



Yocabulary. 



The literary pioneer who breaks ground new to his language is repeatedly 

 confronted with the paucity or want of exactness of his vocabulary. Hakckel 

 in his report on the Deep Soa Medusae of the Challenger, has doue his best 

 to eiirich the English language with many medusological terms, but even his 

 comprchensive list leaves much to be desired when Cladonemidae have to be 

 described. 

 Capitulura = "bouton urticant", a battery of thread cells at the end of a ten- 



tacle cf. Coryiie, Elcuthcria. 

 Cnidact = "Ncsselrippe" = "bandelette urticante", a radially disposed row of 

 cnidoblasts upon the exumbrella. 



