72 



oprinst the -osoplopa nnrl forin a dofinito innrr prrr l^ypr. 



Gerr! has obsorver'' ir> Roiifnirivillia that (hirinp the 

 course of cell niltir-lication the cell hourdaries br— 

 core ir.distinct a?d thc-t the -^eri-heral r.rd certral ruclel 

 are nltrrether identical. But this s'-ecies differs frcr 

 Turritcrsis. rcccrdirp to his descrlTtior ir the fornation 

 of the corract roriila stare, ir that it is brcuf^ht abrut 

 by r; nultirolar ripraticr of cells into the interior of the 

 coeloblastula; v:hile ir Turritprsis the rorula stape results 

 directly frcr se.c:nertation \;itho\it any reco.rnirable rigration 

 of cells. 



The fcr'^aticr of the erdoderr ir Turritcrsis there- 

 fore differs fro- nearly all the -'Cthods v-hich have nrevious- 

 ly beer dercribed; ard v,'hich in the rain conforr to one or 

 another of the sterertyred rethodr as established by i.'etschnl- 

 koff. The nearest arrrcach is that^described by 

 Harritt for Zuderdriun ard Pennaria, in vhich there is also 

 rore or less of a syncytium for"-ed nrior to the differertj- 



