TIMA FORMOSA. 



115 



capsules along the circular tube, and yet these Medustv have all been 



traced to a Canipanularian-like liydrariuni. Tiiua differs from the 



other generca 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. See the 



magnified portion of the circular tube of Tinui (Fig. 1G<S), and compare 



this, crowded with marginal capsules, to the circular tube 



of Melicertum and Lafoea. Having kept in confinement 



males and fenuiles of this species, I succeeded in raising 



from the eggs the Planula, and ultinuitely 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 Ilydrarium ; as this is identical in 



both, I shall only describe the Planula and Hydrarimn 



as far as they differ from those of the Melicertum. 



The Planula is more pear-shaped {]), Fig. 171) than 

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

 taching itself [j), Fig. 171.) The Hydrarimn is also more slender, 

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

 are connected at the base by a n-. 172. 



web (Fig. 172) ; this seems to 

 be a mere emluTonic feature, as 

 I have noticed the same w'eb in 

 several young 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 appeared 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. 



Massachusetts 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. 171. /), young planula ; />', planula immediately before attachin<f itself. 

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



