CLOSTERIUM. 47 



C. DiANJE, Ehrb. Plate VIII, figs. 8, 9. Plate IX, fig. 4. 

 Plate VI, figs. 1, 2. 

 Crescent shape, sometimes a full semi-circle as variety 

 arcuatum, Breb., attenuated from the middle to the rather 

 sharp ends, vacuole not definitely defined ; transverse striae 

 sometimes evident. Ends are separated by about 10 diam- 

 eters. Specimens Plate LV differing somewhat in size. Not 

 rare. Zygospores spherical, smooth. 

 Diameter 16-20 yu. 



Quiet waters, Rhode Island to Florida. 



C. ACUMINATUM, Kg. Plate VIII, figs. 18, 19. 



Similar to Diance, somewhat larger and less curved, ends, 

 sharper, vacuoles more distinct ; membrane very finely 

 striate, or smooth. 



Diameter 25-28 /<. 



Not rare in marsh pools ; conjugated cells frequent. 

 Pennsylvania. 



C. Jbnnert, Ealfs. Plate VIII, fig. 5. 



Crescent shaped, small, slightly tapering, six to eight 

 times longer than broad, ends obtusely rounded ; vacuole- 

 large, containing many active granules; cytioderm color- 

 less, smooth. 

 Diameter about 14 //. 



Rhode Island (Bailey) ; Pennsylvania, New Jersey. 



C. Venus, Kg. Plate VIII, fig. 6. 



Small, more or less slender, nearly semi-circular, eight to- 

 twelve times longer than the diameter ; gradually tapering 

 from the middle to the sharp ends ; vacuole distinct ; cytio- 

 derm colorless and smooth ; chlorophyl homogeneous. 

 Diameter 8-10 jx. 



South Carolina, (Ravenel); Pennsylvania, New Jersey,, 

 frequent. 



C. PAEVULUM, Naeg. Plate VlII, fig. 7 ; and Plate IX, fig. 16. 

 Six to eight times as long as wide ; differs from C. Yenus- 

 in being rather less arched aiid stouter, vacuoles not so well 

 defined, and chlorophyl lamina more evident. 

 Diameter 12 /<. 



