110 



Gaelentera. 



far as the larval stage, in saccular evaginations of tlie oral arms 

 ■of tlie parent; others pass through the early stages in similar 

 •outgrowths of the radial canals. 



The polypoid generation. When the ciliated larva, 

 developed from the egg, leaves the parent, it attaches itself to some 

 foreign body, and grows into a small polyp with a circlet of tentacles. 



Kg. 65. The development of Aurelia. 1 free larva. 2 the polyp, a short 

 -time after attachment. 3 the same somewhat later. 4 transverse fission. 5 later stag^e. 

 •6 the polyp after the separation of a number of young Medusa. 7 — 9 the young Medusse 

 at various stages of development. 7 — 8 viewed from below. 9 from the side. — After 

 M. Sars. 



Like Rydra, this polyp may form huds, which separate off and 

 -develop into adults like the parent, but no true colony is formed. The 

 polyp, which is at first relatively short, gradually grows to a con- 

 siderable length, becoming cylindrical, with a conical base. Next, 

 a number of annular constrictions appear, dividing the main portion 

 ■of the body into a series of discs, which separate from each other, 

 and, breaking away from the polyp, form small Medusse. In 

 exceptional cases the polyp generation is absent, the medusa-egg 

 .developing direct into a new medusa. 



