TIMA FORMOSA. 



115 



Fig. 171. 



capsules along the circular tul)e, and yot these Medusae have all been 



traced to a Canipanularian-like Ilydrarium. Tinia differs from tlie 



other genera just mentioned, in developing eventually these marginal 



capsules, which are always wanting, at least in the shape of capsules 



with limestone concretions, in the above-mentioned genera. Sec the 



magnified portion of the circular tube of Tima (Fig. 1G8), and compare 



this, crowded with marginal capsules, to the circular tube 



of Melicertum and Lafcea. Having kept in confinement 



males and females of this species, I succeeded in raising 



from the eggs the Planula, and ultimately the Hydra- 



rium, as in the case of Melicertum, where further details 



will be found concerning the mode of development of 



the Planula into the Hydrarium ; as this is identical in 



both, I shall only describe the Planula and Hydrarium 



as far as they dift'er from those of the Melicertum. 



The Planula is more pear-shaped (p, Fig. 171) than 

 that of the Melicertum, and takes a far greater elongation before at- 

 taching itself {p. Fig. 171.) The Hydrarium is also more slender, 

 the cup is more distinct, the tentacles are quite long and slender, and 

 are connected at the base by a 

 web (Fig. 172) ; this seems to 

 be a mere embryonic feature, as 

 I have noticed the same web in 

 several yomig Campanularians. 

 The Hydrarium here figured at- 

 tained its present features at the 

 end of six months. The com- 

 munities are very small tufts, 

 barely perceptible to the naked 

 eye ; they appeai'ed like a few 

 slender threads on the side of 

 the glass vessel in which the 

 Planula was raised ; I did not 

 succeed in raising the Hydrarium to observe its further develop- 

 ment. 



Ma.ssachusetts Bay (L. Agassiz). 



Cat. No. 276, Cape Cod, March, 1862, A. S. Bickmore. Medusa. 



Cat. No. 372, Nahant, September, 1863, A. Agassiz. Medusa. 



Museum Diagram No. 17, after A. Agassiz. 



Fig. 172 



Fig. 171. ji. younij planula; /)', planula immediately before attaching itself. 

 Fig. 172. Single Hydra of the tuft of a Tima Hydrarium, greatly magnified. 



