286 R. E. Lloyd : A new gcinis of Hydroids. [VOL. I, 



structures, of about uniform size throughout, arising from differ- 

 ent points of attachment at the base from the gonosomes They 

 are, Hke the gonosomes, destitute of appendages, but they prob- 

 ably have an opening at the free extremity. The walls of the fili- 

 form bodies are composed of an outer thin and an inner thickened 

 layer. There is a cavity within. The walls are dotted with pig- 

 ment spots, which are especially numerous around the free extrem- 

 ity. In one of these filiform bodies there is a spherical mass, 

 which resembles half-digested food. It is doubtful whether this 

 mass is food. The free end of the filiform bodies is sometimes 

 trumpet-shaped, but ordinarily rounded, the opening being con- 

 cealed by the contraction of the lips. The bodies of the filiform 

 structures move backwards and forwards on their attachments, 

 and are sometimes spirall}^ coiled in a single turn. They recall in 

 general appearance the spiral zooids of Hydractinia and the 

 tasters of Siphonpphora, but, unlike either of these structures, 

 have an orifice at their free end. They are thought to have close 

 likenesses to the ' central polyp ' of Velella." 



The difficulty of interpreting the nature of the fiask-shaped 

 bodies of Hydrichthys , becomes lessened in the light of the new 

 genus Nudiclava ; and the present writer is strongly of the 

 opinion tnat the flask-shaped bodies of the former and the 

 club-shaped bodies of the latter are both hydranths devoid of 

 tentacles. Furthermore, that it is by means of these hydranths 

 that the colonies obtain their food. In his description of Hydrich- 

 thys, the author expresses the following view of its mode of 

 nutrition, a view expressed, necessarily at that time, somewhat 

 doubtfully : — 



" The absence of tentacles, or organs the function of which 

 is the capture of food, would seem to deprive Hydrichthys of 

 those means of capturing and drawing food to the mouth which 

 are almost universal among fixed hydroids. Possibly in its 

 parasitic life the hydroid obtains its sustenance from the fish on 

 the sides of which it lives." 



The close resemblances in the structure of the two forms 

 now under comparison make it most probable that, whatever the 

 mode of nutrition, it is of a similar nature in both cases. It 

 seems from the following observations, that the genus Nudiclava 

 does not obtain sustenance from the fish to which it is attached. 

 It was previously mentioned that on removing a portion of the 

 colony, an outer layer of the fish's skin was removed with it. 

 Part of this was separated from the hydroid and examined 

 microscopically ; it was found to be quite intact ; there was no 

 sign of perforation by any radical organs. In the absence of any 

 such special organs, it does not seem likely that the fish would be 

 so accommodating as to diffuse nutriment, uncompelled, through 

 its own skin into the tissues of the hydroid. 



How, then, do these colonies obtain their food ? The as- 

 sumption is made here, that Hydrichthys and Nudiclava obtain 

 nutriment in the same way. The absence of tentacles in these 



