56 DE8MID8 OF THE T'XITED STATES. 



C. Clevei, (Lund), Wolle. (Penium Clevei, Lund). Plate L, 

 fig. 27. 

 Cell subcylindrical, 2h-S times longer than broad, some- 

 what constricted in the middle; .semi-cells cylindric-subconi- 

 eal, ends distinctly attenuated and rounded at apices ; vertical 

 view a perfect circle. Nuclei large, elliptic, single or rarely 

 twinned. Membrane finely punctate, at apices subgranulate 

 punctate. 



Diameter 40-50 u. Length 1 1 5-1 IK ft. 



Brown's Mills, New Jersey. 



The plant is slightly larger than Lundell's form, but so 

 good a counterpart in form and structure, I take it to be the 

 same species ; by measurement the constriction is somewhat 

 deeper. The decided constriction makes the natural position 

 of this form, I think, a member of the present genus, not- 

 withstanding the observations made by Lundell in the 

 arrangement of the chlorophyl. 



C. Thwaitkhi, Ralfs. Plate XII, fig. 19. Plate L, t\i:. 28. 



Cellsjtwo to three times longer than broad, fusiform in front 

 view; circular in end view ; constriction a -hallow sinus; 

 end- high-rounded, cytioderm not at all, or very indistinctly 

 punctate; chlorophyl scattered. 



Diameter about 30 u. 



Florida, (Bailey); frequent in pond, Spring Lake, Mon- 

 mouth County, New Jersey. 



C. diplospora, Lund. Plate XII, fig. 18. 



Cell large, twice as long as broad, subcylindrical, moder- 

 ately constricted in the middle, very -lightly but distinctly 



enlarged from the centre towards the end-; apices broadly 

 rounded; end view circular : cytioderm colorless and smooth. 

 Cytiopla-ni ha-ji-ually a tint of reddish brown. 



Diameter 25-30 fi : length 53-68 fJL. 



Frequent in ponds, Berkshire Mountains, Massachusetts. 



C. 006TATUS, Wolle. Plate XII, fig. 13. 



Cell oval i form, nearly twice as long as wide ; moderately 

 constricted in the middle. Front view a constricted oval, end 

 view circular; cytioderm longitudinally costate ; costae 5-7, 



