CLOSTERIUM. 23 



Mr. Turner of England who reports this form from Minne- 

 sota remarks, "As I do not know of the publication of any 

 measurements or authentic figure of this species, I may pos- 

 sibly be in error in referring these American forms to it : 

 the figures therefore must speak for themselves." 



Diameter of cells 23-31 ju ; length of double cell as figured 

 227-260 p. 



Another form, Plate LXI, fig. 19, which may for the 

 present, be referred to this species, I found frequent in the 

 Tocoi marshes, Florida. It is unlike the preceding in the 

 absence of the transverse sutures or rib-like projections ; in 

 the variableness of diameter and proportionate lengths. 

 Diameter of smaller forms 15-18 /* and of larger form 37 yw. 

 The smaller are 10-14 and the larger 7 times longer than 

 broad. 



Chlorophyl usually thrice interrupted. 



P. CRUCIFERUM, (D.BY.) Wittr. Plate LXI, figs. 9-11. 



Cells cylindrical, nearly twice as long as wide, scarcely 

 constricted, ends roundly truncate ; seen from vertex orbic- 

 ular ; chlorophyl laminae arranged in form of a cross as seen 

 in transverse section ; cytioderm smooth. 

 Syn. Oosmarium cruciferum, D.By. 

 Marsh pools, Florida. 



P. (Cylindrocystis ) TUMIDUM, F. Gay. Plate LVI, figs. 7, 8. 



Cells twice as long as broad; each semi-cell a broadly 

 truncated cone. Cytioderm smooth. 



Diameter 28 JJL. 



Frequent in Tocoi marshes, Florida. 



Genus, CLOSTEEIUM. V. Des. U. S. p. 37. 



C. JUNCIDUM, (Des. U. S. p. 38,) forma GBACILLIMA-LOEVISSIMA, 



Breb. Plate LV, fig. 21. 



Very much smaller than the type-form and destitute of 

 striae. 



Frequent in pond near Maitland, Florida. 



C. ENSIS, Delp. Plate LV, figs. 13, 14. 



Cell elongate about twenty times longer than broad, sub- 

 linear, or lightly attenuated from the middle to the apices 5 

 ends not curved ; cytioderm smooth. 



Diameter 36 yw. 



Not rare in ponds, Minnesota, Pennsylvania and New 

 Jersey, 



