36 CCELENTEKATA AND 



Hdlecium. Plant-like, branched, rooted by creeping 

 stolon. Hydrothecee biserial, tubular, bell-shaped, sub- 

 sessile, jointed to short lateral process. Hydranth par- 

 tially retractile. Fixed sporosacs. 



H. gracile. 

 Lovenella. Stem simple, branched, thread-like stolon. 

 Hydrotheca turbinate, elongate, crowned with a conical 

 operculum. 



L. gracilis. 



Olytia. Stem simple, branched slightly. Creeping 



stolon. Hydrotheca: bell-shaped. No operculum. Hy- 



dranths with large trumpet-shaped proboscis. Medusae on 



stolon and stem. 



Medusa, Clylia. 



C. Johnstoni. 

 Obelia. Stem branching, plant-like, creeping stolon. 

 Bell-shaped. No operculum. Gonothecge on stem and 

 branches. 



O. gelatinosa. 



commisuralis. 



Campanularia. Stem simple, branched, filiform stolon. 



Hydrothecaa bell-shaped. No operculum. Hyaline. Hy- 



dranths with cup-shaped proboscis. 



Gonophores fixed sporosacs, which mature in the cap- 

 sule. 



O. caliculata. 

 Thawnantias. Stem simple or branched, rooted to 

 thread-like stolon. Calycles campanulate, with funnel- 

 shaped proboscis. 



Gonothyrcea. Stem erect branching, thread-like stolon. 

 Hydrotheca3 bell-shaped, transparent. Proboscis promi- 

 nent, contractile. 



G. tenuis. 

 Qampanulina. Stem slender, annulated. Calycles thin, 



