ACALEPHAE. 



161 



into a Strobila (Fig. 132 /). The separation of the segments progresses 

 continuously from the anterior end to the base of the Strobila, so 

 that after the disappearance of the tentacles (Fig. 132 g), first the 

 terminal segment, then the second, and so forth, attain independent 

 existence (Fig. 132 h). Each segment becomes an Ephyra (Fig. 131), 

 developing eight pairs of elongated marginal lobes, with a marginal 



FIG. 132. e, scyphistoma with sixteen arms (slightly magnified) ; Gw gastral ridges ; 

 /, commencing strobilisation. 



body in the notch which separates the two lobes of the same pair. 

 It is these marginal lobes which give to the edge of the umbrella of 

 the Ephyra its characteristic appearance. The young Ephyra gradually 

 acquires the special peculiarities of form and organization of the 

 sexually mature animal. 



The number of nematocysts accumulated on the upper surface of 



