PIJELIMINARY NOTES ON SOME TETRACTI- 

 NELLIDS OF THE BAY OF NAPLES. 



BY 



G. C. J. VOSMAER. 



lü the following lines I will endeavor more exactly to deter- 

 mine those tetractinellid Sponges of the Bay of Naples, which 

 have been only insuflficiently described and which have proved to 

 vary to such an extent, that any one who is not well versed in 

 systematic spongiology, can easily be misled. 



The more specimens one has studied carefully and the more mi- 

 croscopic sections as well as preparations of isolated spicules one 

 has compared , the more the conviction imposes itself that species 

 vary enormously, and that each species has a great uumber of 

 modifications, which at most should be called »varieties". A good 

 mauy specific names can consequently be dropped and conside- 

 rable simplification can thus be obtained. 



I have often insisted upon this point; however with only a 

 moderate success. Yet I do not intend to give it up. As before , 

 I still believe that there is e. g. but one species of Thenea. The- 

 nea muricata (Bwk.) Gray has more than twenty synonyms. Even 

 those species, which have been carefully described by Sollas in 

 his elaborate Report on the Tetractinellids ^) as Thenea schmidtii, 

 grayi, wy villi , delicata, wrighti, intermedia etc. are according to 

 me nothing more than varieties, for which uo special name is 



1) Challenger Reports. Zoology Vol XXV (188S). 



