124 



LAFCEA CALCARATA. 



appendages [h, Fig. 187) Biade up of large polygonal cells, perfectly 

 transparent, one or two sometimes placed between each of the larger 

 tentacles. The large tentacles have the same color as the ovaries. 

 The young Medusa3 differ from the adult in the extent of the ovaries, 

 which are limited to the upper part of the chymiferous tubes, close 

 to the digestive cavity (Fig. 188) ; the ovaries gradually extend 

 further towards the circular tube as they grow older ; the digestive 

 cavity is a simple cylinder pressed in, formmg small lips ; the tentacles 

 also, as described above, are less numerous. The adult Medusa is very 

 Fig. 189. active, moving with great rar 



pidity, by drawing its tentacles 

 into the bell, throwing them 

 out again with violence, and 

 allowing itself to be carried 

 along by the momentum it has 

 acquired; twisting its tentacles 

 during that time, and spread- 

 ing them in every conceivable 

 manner. When it is lazily car- 

 ried along, the bell often assumes strange attitudes ; the thick upper 

 part of the disk becomes rounded, and the thin j)ortion of the umbrella 

 is projected beyond it, like the rim of a four-cornered hat. (Fig. 189.) 

 At other times it seems as if the umbrella had been tied in the middle, 

 the upper and lower part of the disk almost joining in the middle at an 

 obtuse angle. The next moment the disk becomes perfectly flat, the 

 tentacles are drawn up in close knots or shortly-twisted coils, so that it 

 scarcely seems to be the same animal, which in a moment assumes 

 again a globular shape, and darts off to go through the same changes 

 of form. 



The Medusa in its youngest stage resembles closely the figure given 

 by Wright of the Medusa of A. repens in the Edinburgh Philosophical 

 Journal. The Hydromedusarium differs so much, that it does not seem 

 Fig. 190. to belong to the same genus as 



the English species ; it is found 

 growing along the stems of a 

 species of Dynamena, found 

 just below the hue of low- 

 water-mark. The individuals 

 are arranged, in a quincunx manner, on both sides of a long, slender, 

 creeping stem, which does not branch. It resembles a true Campanu- 

 laria in having a transparent bell disconnected from the stem. Other- 



■what injured 



189. Different attitude of the Medusa of Fig. 184. 



1 90. Hydrarium of Lafoea calcarata ; the extremity of the reproductive oalycle is some- 



See Fi<T. 191. 



