f^ HYDROZOA, 47 



panularia, for example, columnar gonoblastidia 



arise in the angles between the stem and branches 



of the coenosarc, or from the sides of the branches 



I ^ themselves (figs. 10 and 19). The lower portion 



a % of each gonoblastidium forms a sort of peduncle, 



^°*he.\ above which the cuticular investment of its ec- 



^desjC toderm becomes separated as an urn-shaped cap- 



a i . sule, the 'gonotheca.' Such capsules, or "ovigerous 



tpport vesicles," are very variable and beautiful in form. 



True gonophores, protected by the gonotheca, are 

 Dpl e 1 borne along the sides of its axial column. 

 . m l In some Calycophoridce and Physophoridce, 



^ t particular regions of the hydrosoma may devote 

 tt ]- themselves to the performance of the reproductive 



function, and, becoming separated from the rest 

 of the fabric, subsequently undergo a surprising 

 > T amount of modification. 



idia 



uuia % 



» 



Finally, in the Lucernaridce, with the exception 



rhose m of Lucevnaria and a few closely-allied genera, the 



. 



polypites 



are 



in 1; in their detached condition, grow with such ra- 



•*-».■« J - j_ — ^ „ "I i* ill ■ 1 « ._ _ 



e pyi' 



attain 



jj , . pounds, or even hundreds. A corresponding ad- 

 vance in structure attends this vast increase of 

 ^ s 1Z e. Each, at the outset of its free existence, 



includes a complete transverse segment of the 

 polypite from which it has separated. This soon 

 forms a lobed swimming organ, or umbrella, with 



nar 

 korai. 



uue uooueu ntnocysts betore mentioned. From 

 *■ the centre of the umbrella hangs a large polypite, 



whose lips, in such genera as Aurdia, Cyanea, 



and Chrysaora, form lobes of considerable length, 



LlQ m the folds of which serve as temporary receptacles 



