578 Cluis. W. Hargitt 



of tbc Neapolitnu fauna. It was first studied by the present writer 

 in 1S94 and ag-ain duriug- the summer of 1903, at which time it 

 was obtaiued in various stag-es, from small, single polyps growing 

 among the remains of old and mostly dead colonies of Eiidendriuni 

 and Pennaria. This fact naturally recalled the belief of Cavo- 

 lini that it was parasitic upon the former of these hydroids, one 

 of the few points in its original description in which the Neapolitan 

 naturalist was undoubtedly mistaken, as Wkismann has proven, and 

 as I have also been able to contimi, in that finely developed colo- 

 nies have been obtained wholly free from any association with 

 Eudendriuni^ or other hydroid, growing indeed upon fragments of 

 rock, etc. 



Allman 1 in describing this hydroid, knowledge of which 

 was derived entirely from Cavolini's description, expressed some- 

 what emphatic doubt upon severa! points of habit, structure, etc. 

 Among them is that of its parasitism referred to in the preceding 

 l)aragraph. Another had reference to its life history, Allman claim- 

 ing that it wüuld undoubtedly be found to have a free medusa stage, 

 and further that the claim of Cavolini to have traced the origin of 

 eggs and embryos was as undoubtedly erroneous as he believed the 

 other features to have been. He says concerning this point 'It is 

 far more probable that the egglike bodies are parasitical organisms 

 than that they have any direct relation with the hydroid'. He is 

 likewise in error as to the fascicled condition of the stems of the 

 hydroid. 



It remained for Weismann 2 to show that Allman's contentions 

 were, with the exception of that referriug to parasitism, without 

 fouudation in fact. 



My own observations have confirmed those of AVeismann ou 

 these points without exception. 



Weismann's account of the essentials of structure, habits, etc., 

 is so full and admirable that it is unnecessary to undertake here 

 to review or repeat it. What follo ws has to do almost wholly 

 with matters of development, concerning which Weismann records 

 little beyond such aspects as come within the province of his par- 

 tieular problem, namely, tlic origin of the sex-cells. 



' A Mouograi)h of the Gymnoblastic Hydroids. London 1871 pag. 263. 

 - Die Entstehung der Sexnalzellen bei den Hydromedusen. Jena 1893 

 pag. •'}.") etc. 



