10 THYROSCYPHUS. 



This is a very large, strong form, rendered striking by its regularly pin- 

 nate hydrocaulus, and its large, nearly cylindrical hydrothecse, with perfectly 

 even orifice margined by a narrow clear band. 



Without a knowledge of the gonosome its reference to Obella must be 

 regarded as purely provisional. 



The beautiful little Lafoea venusta crept over the stem and pinnae of one 

 of the specimens. 



Obelia longicyatha. 



PI. VII. Figs. 4, 5. 



Trophosome. — Hydrocaulus attaining a height of nearly an inch, fascicled 

 below, alternately branched ; main stem annulated for a short distance above 

 each ramulus; ramuli annulated at their origin; hydrothecal peduncles of 

 moderate length, more or less annulated. Hydrothecaa narrow, deep, nearly 

 cylindrical above, and then tapering towards the base; the orifice cut into 

 about twenty acute, deep, narrow teeth. 



Gonosome not known. 



Dredged from a depth of 90 fathoms off the Florida Reef. 



The specimens were found attached to Halecium macrocephahmi. It is a 

 delicate species with the hydrothecae very thin and compressible. No gono- 

 some was present, and its reference to Obelia is therefore only provisional. 



THYROSCYPHUS Allman nov. gen. 



Geneeic Character. Trophosome. — Hydrocaulus divided into internodes, 

 each internode carrying a hydrotheca. HydrothecEe pedunculate ; orifice 

 closed by an operculum which is formed by four converging valves. 



Gonosome not known. 



The small and definite number (4) of valve-like segments composing the 

 operculum of the large and strong hydrothecse, combined with the very 

 definite division of the hydrocaulus into distinct and equal internodes, dis- 

 tinguishes the genus Thyroscyphus from the other operculate genera of the 

 Campanularida;. It is highly probable that if we were acquainted with 

 the gonosome other and still more important characters would be foimd. 



