PHYLUM CCELENTERATA 



"3 



similar to that which has been described in the case of 

 Aurelia, with a fixed scyphistoma stage ; but in others the 

 ciliated larva; developed from the ova give rise directly to 



gen 



mnt> 



fp.vt irt ^ 



i.r. 



Fig. 53.— Tessera princeps. A, external view; E, vertical section; g. _/, gastric 



filament; gon, gonad; i.r.t. tentacle; ;;/;//', manubrium; mth, mouth; p.r.t, 



tentacle; st, stomach; tn, taniiole or gastric ridge. Antarctic Ocean. (After 

 Haeckel.) 



jellyfishes like the parent, without the intercalation of any 

 fixed stage. 



The Scyphozoa are all marine, and the majority are 

 pelagic, i.e., swim freely in the surface waters of the ocean. 

 1 



