560 VICTORELLID.E. 



only seen a few mounted cells (wbicli I owe to Mr. Kent^s 

 kindness), and have therefore had no opportunity of 

 making a minute study of the structure. But a few 

 points it has been possible to determine. 



The endosarcal cord which pervades the stolon dilates 

 as it enters the cell-like expansion, and takes the form of 

 a plexus-like tissue, which partially fills the cavity, and 

 within which the polypide is developed. The expanded 

 and more or less ovate portion of the stolon is closed 

 above by a diaphragm, beyond which the stem is con- 

 tinued. At its upper end, and immediately below the 

 diaphragm, a tubular projection rises in front, which is 

 the rudiment of the erect portion of the adult cell. At 

 this stage (as represented in Plate LXXIX. fig. 7) the 

 forming polypide consists of an ovate body, prolonged and 

 attenuated below, where it seems to be doubled upon it- 

 self, and above continued into a kind of neck, which 

 reaches to the top of the tubular i3rojection. The later 

 course of the development I have not been able to follow; 

 but the polypide must increase greatly in size to fill, as it 

 does, the erect tube into which it is ultimately withdrawn. 



These fragments of the developmental history of Vic- 

 torella give the following results : — 



1. They confirm Joliet^s views respecting the formation 

 of the polypide out of the endosarc. 



2. They suggest very forcibly the homology between 

 the zooecium and the stolonic internodes amongst the 

 Ctenostomata. 



3. They indicate the primitive condition of the zocecium, 

 and give us a clue to the meaning of the stolonic expan- 

 sions in such a form as Aetea, and to the mode in which 

 the tube may have been gradually superadded in the 

 latter to a simple hippothooid cell. 



