84 THE AQUARIAN NATURALIST. 



movements of contraction and expansion, precisely 

 like those exhibited by the free Acalephse, were di- 

 stinctly visible ; in the course of about a quarter of 

 an hour the upper individual of the group detached 

 itself from the rest and swam away, an example which 

 was immediately followed by the rest in rapid suc- 

 cession ; so that in the course of an hour from the 

 commencement of this strange breaking-up, the whole 

 colony had separated, and its various members were 

 seen swimming about in the watch-glass under the 

 form of minute Medusae. 



The colour of the little Medusae, when first libe- 

 rated from the Strobila, is a delicate red, or rather 

 they are perfectly transparent, but dotted with minute 

 red points, although occasionally they are as pellucid 

 as crystal. They swim about with great vivacity, 

 alternately contracting and expanding the little rays 

 surrounding their disc; but whether their course 

 through the water be in a vertical or horizontal di- 

 rection, the convex surface of their body is always 

 foremost. Sometimes they will sink motionless to 

 the bottom of the water, as though to rest themselves, 

 resuming after a while their merry evolutions with 

 increased energy. If one of them is touched while 

 swimming, it immediately folds up its rays over its 

 mouth and sinks, but soon recovers itself, and, if left 

 undisturbed, resumes its evolutions in the water. 



Although these little creatures are more tenacious 

 of life than the majority of the larger Acalephs, it has 

 been found impossible to keep them for any length of 

 time in confinement; for about eight or ten days 

 they continue to swim about with undiminished 



