342 L. MURBACH. 



ward learned^ there was simply a tubular secretioUj only shreds 

 of which remained on the captured polyps. 



Last summer (1897) more specimens were obtained by 

 allowing the tow-net to scrape gently over the eel-grass. 

 These seemed to warrant my previous conjectures, and 

 although specimens were sometimes taken in clear water, I 

 now concluded that they usually are temporarily attached to 

 submerged refuse, eel-grass, &c., by means of their perisarcal 

 secretion. 



The attached condition of marine hydroids is so universal, 

 and those able to move from place to place are so few, that up 

 to the present time not much stress has been laid on this 

 characteristic. More cases of this kind would establish such 

 character as very primitive or as reversion to an ancestral 

 type, a free polyp, perhaps Actinula-like. 



To the writer's knowledge there are only two marine forms 

 so far known which may be considered free. They are 

 Protohydra Leuckartii and Halermita cumulans. 



The former, long ago discovered by GreefF,^ was con- 

 sidered, as its name indicates, to be an ancestral form of 

 hydroids, but its foot is adapted for fixation, and is therefore 

 of permanent character. Furthermore, no sexual reproduction 

 has up to the present time been observed, and partly for this 

 reason Schaudinn ^ suggests that it may be the larval form 

 of a more highly organised polyp. 



Halermita, discovered by Schaudinn- in the Berlin 

 Aquaria, is certainly a remarkable form, and as his report of 

 the finding may not be accessible to all, I shall recount the 

 principal features of the polyp. Its name indicates its solitary 

 mode of life. In form it is short and conical (stumpf kegel- 

 fiirmig). There are no divisions into hydranth and hydro- 

 caulus ; the tentacles (the figures show only one circlet) are 

 usually four in number, but never more than five, and these 



' Greeff, E.., "Protohydra Leuckartii," ' Zeitsclir. 1". Zool.,' Bd. xx, 

 1870. 



2 Schaudinn, F., "Halermita cumulans," ' Sitzber. d. Gesellsch. Nat. 

 Freunde,' Berlin, 1894. 



