duced two secondary ones, one on each side of the rhopalial 

 tentacle. These are connected by a slight ridge, that cross- 

 es the base of the tentacle on its aboral side, (h. Fig. 40) 

 These secondary lobes are the rhopalial lobes of the margin of 

 the umbrella (Fl'iigellappen of German authors) and the connect- 

 ing ridge is the hood (Deckplatte) that covers the rhopalium. 

 These marginal structures may be seen in Fig. 17, and this 

 brings us to another stage in the deve'^opment of the rhopalium, 

 the absorption of the distal part of the tentacle. 



In the strobila shomi in Fig. 17 the rhopalial tentacles 

 have a very different appearance from what we have seen before. 

 They are shorter than the other tentacles ar.d are much swollen 

 at a point just beyond the eye spot. The distal portion is 

 beginning to degenerate. This process, when once begun, pro- 

 ceeds rapidly. During the few hours that were spent in making 

 Lhis drawing, the rhopalial tentacles were reduced in length 

 nearly one half. The eye spots and concretions were conspic- 

 uous and in each of the former there was a slight cup-shaped 

 depression. This is the earliest stage in which I observed 

 slight medusa- like movements of the ephyra disk. ^igs 41 

 and 42 are rather oblique sections al right angles to one ano- 

 ther of rhopalia au about this stage. The tentacle is seen 

 to be in a process of degeneration for about fifteen-hundredths 



- 43 - 



