22 Invertebrate Zoology. 



resultant nutritive fluid is carried, by the action of cilia, to 

 all parts of ccelenteric cavity. At the upper portion of 

 each mesentery circular openings are to be found, placing 

 the contiguous chambers in communication, and thus allow- 

 ing free circulation. These openings, the septal stomata, 

 form imaginary rings around the upper end of the oesopha- 

 gus, and are possibly comparable with the circumferential 

 canal of the Hydromedusa. 1 



Make drawings that will illustrate the more important 

 points in the internal anatomy. 



1 The inner septal stomata are placed just below the peristome near 

 the oesophagus and pierce only the primary septa. The outer septal 

 stomata are near the outer-wall and pierce all the septa. 



