62 



HYDEOZOA. 



cavity is formed throughout the central portion of 



the mass. Even at this period the larva produces 



free buds from its proximal extremity, not more 



than two appearing to arise at the same time, 



though the process of gemmation may frequently 



be repeated. Next, the distal region elongates ; 



the nutrient cavity opens at its free extremity, 



forming a mouth ; and thus a young polypite is 



produced, while from the proximal margin two 



new tentacula soon make their appearance. From 



this region a rudimentary nectocalyx now arises, 



a fold, in which are developed marginal bodies, 



appearing, distal ly, in front of the tentacles, 

 between which four other tubercular lobes are 



now seen to bud forth. The growth of the nec- 

 tocalyx slowly proceeds; eight marginal bodies 

 distinctly come into view ; the polypite diminishes 

 in size, finally becoming inconspicuous ; and the 

 animal attains the adult form characteristic of its 

 family, save only that reproductive organs have 

 not yet been observed. 



That instances of the above kind should be mul- 

 tiplied and re-observed seems, for many reasons, 

 very desirable, since, as already remarked, not a 

 few of the forms known as Meclusicloe are but the 

 free-swimming gonophores of various other Hy- 

 drozoa. Thus, from the ovum of Turns, one of 

 the so-called genera referred to this order, a poly- 

 pite is produced, which sends forth a creeping 

 coenosarc, giving rise to a hydrosoma, clearly seem 

 to belong to the Corynidcv (fig. 13). Dr. T. 

 Strethill Wright has further proved that Bougain- 

 villea Britannica, a common form of Medusoid, 

 is, in truth, the reproductive body of AtraetyK* 

 ramosa, one of the Corynidce. 



