644 



MEDUS,E OF THE WOULD. 



hud is set free as a spindle-shaped larva which swims by means of cilia. After 2 or 3 days the 

 mouth breaks through at the pole which was at the proximal end of the bud while it was 

 attached to the parent, thus resembling the case of budding in Cotylorhiza. The mouth is 

 not formed by an invagination ot the ectoderm, but breaks through by the local disappear- 

 ance of the mesoglcea and the fusion of ectoderm and entoderm at the posterior end of the 

 larva. The anterior end then elongates to form the stem of attachment, and in about 4 or 5 

 days after being set free the larva fastens itself to some solid object. 



23 



FIG. 403. Cassiopea xamachana, after R. P. Bigelow, in Mem. Boston Soc. Natural History. 



//, interrhopalial tentacle; oc, ocellus; rht, rhopalial tentacle; .v, abnormal branched tentacle. 



17, scyphostoma showing first traces of rhopalial structure. 18, small part of margin, more highly magni- 

 fied. 19, scyphostoma at slightly older stage. 20, small part of margin of similar larva, zi, 

 early stage in stabilization. 22, rhopalial tentacle of same specimen seen from side. 23, older 

 rhopalial tentacle. 24, strobila in which rhopalial tentacles have begun to degenerate. 



