96 E. PERCIVAL 



in the floor of the mouth angles ', adding ' but this may not be 

 the whole explanation '. 



In both ephyra and scyphistoma the use of powdered carmine 

 seems to show that the lining of the proboscis or the manubrium 

 has cilia which may produce exhalant or inhalant currents 

 when necessary. The stream of particles passes down the angles 

 in the perradii as well as along the ridges of the interradii ; 

 further, expulsion of material may follow the same channels. 

 In only one case did I observe both currents acting simultane- 

 ously, and then the in-currents moved along the interradial 

 ridge and the ex-currents along the perradial angles. A 

 strobila shows a strong current from the foot upwards to the 

 uppermost ephyra. This is due to the fact that the surface 

 is composed of a considerable portion of the aboral surface of 

 each ephyra, on which surface the current is centrifugal to the 

 ends of the lappets. There did not appear to be any passage 

 of carmine in between any two ephyra rudiments. This 

 suggests that the intermediate ephyrae or ephjTa rudiments 

 do not feed by means of these currents. 



High power examination shows that the currents are caused 

 by flagellated ectoderm cells (PI. 6, figs. 6 and 7). The ectoderm 

 of the scyphistoma, except on the pedal disc, and of the 

 ephyra appears to consist entirely of flagellated cells. Even 

 the surface of the tentaculocyst is provided with flagella. 

 When death takes place, either naturally or by poison, the 

 flagella usually disappear. Occasionally in a well-fixed specimen 

 they still persist and can be studied by means of sections. 

 In the case of the lining of the manubrium or of the proboscis 

 the flagella are almost always visible in sections, an interesting 

 point which corroborates the histological evidence as to the 

 endodermal nature of this lining. 



Eemarkable cases of Polyp Formation. — While 

 keeping under observation a young strobila for the purpose of 

 watching the transformation of the oral disc into an ephyra, 

 I was able to observe a number of interesting but unexpected 

 changes. There were five constrictions in the strobila, and 

 the two ephyra rudiments next below the oral disc proceeded 



