EMBRYOLOGY OF CYANEA AURITA. 115 



of their development, neither do they remain in the ovigerous cavity, 

 but escape from the orifice of the latter into the surrounding water, 

 from whence they are again taken up by the tentacula and by the two 

 laminae of the arms, and become lodged in little pouches formed by the 

 laminated margin, in which they undergo further metamorphosis and 

 development. These ovigerous pouches are only met with at certain 

 seasons, disappearing when their functions are accomplished. 



(298.) The eggs are of a rounded form and covered with a smooth, 

 thin, membranous envelope whilst they remain in the ovary ; internally 

 they are filled with a finely- granular mass of a violet hue. 



(299.) The ova contained in the arm-sacculi are destitute of any 

 shell, and present themselves under three distinct forms, which are very 

 remarkable. Some resemble blackberries, and are of a pale violet hue ; 

 others have the shape of minute thick disks, likewise violet, resembling 

 little Medusae deprived of arms and without any nutrient canals ; lastly, 

 others are met with (and these latter are the most numerous) which 

 have a cylindrical shape, truncated at both ends, and of a brownish- 

 yellow colour. The two last-mentioned forms are densely covered with 

 cilia, and swim about with facility ; the largest among them measure 

 about -Jth of a line in diameter. 



(300.) Subsequently the ciliated embryos, escaping from their con- 

 finement, detach themselves from the cradles wherein they have been 

 nursed up to this period, and swim freely about in the surrounding 

 water until ripe for a further change in their economy; they then 

 settle down upon some foreign object, such as a piece of sea- weed, to 

 which they attach themselves by one extremity (fig. 54, 3), assuming 

 the appearance of a contracted Hydra, but, as yet, unprovided either 

 with mouth or tentacula; gradually, however, an oral aperture and 

 stomachal cavity, surrounded by tentacular organs, become apparent ; 

 and as these progressively increase in number (fig. 54, 4, 5, 6, 11), the 

 little creature assumes completely the polyp form, and, what is still 

 more wonderful, acquires in this early and, as it might be called, larva- 

 condition of its existence the power of multiplying itself under the 

 same shape, apparently ad infinitum. 



(301.) This kind of reproduction is effected by the development of 

 stolons, gemmce, and lulblets from any portion of the surface of the 

 polypoid animal, which in turn give origin to similar offsets (fig. 54, 12, 

 13, 14), precisely resembling, when mature, the original polypoid body. 



(302.) The next phasis in the development of these Acalephs is one 

 of the most remarkable circumstances connected with their history, 

 and, were it not for the accumulated testimony of numerous observers, 

 might appear almost incredible. The polyp, much in the condition 

 represented at fig. 54, 11, is immovably fixed by its basis to the surface 

 of a Eucus, or some similar support ; in length it is about -1-th, and in 

 diameter J^-th of an inch ; its surface is smooth, and its texture alto- 



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