COSMARIU.M. 61 



sinus; ends liigb-rounded, cytiodei-m not at all, or very in- 

 distinctly punctate ; chlorophyl scattered. 

 Diameter about 30 f^. 



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

 mouth County, New Jersey. 



C. DiPLOSPOEA, Lund. Plate XV, fig. IS. 



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

 ately constricted in the middle, very slightly but distinctly 

 enlarged from the center towards the ends ; apices broadly 

 rounded ; end view circular ; cytioderm colorless and 

 smooth. Cytioplasm has usually a tint of reddish brown. 

 Diameter 25-30 yu. ; length 53-58 fx. 



Frequent in ponds, Berkshire Mountains, Massachusetts. 



C. cosTATDS, Wolle. Plate XY, fig. 13. 



Cell ovaliform, nearly twace as long as wide ; moderately 

 constricted in the middle. Front view a constricted oval, 

 end view circular ; cytioderm longitudinally costate ; costae 

 5-7, distinct, converging at the apices. Color of older ijlants 

 reddish brown. 



Diameter 50 yU. ; length 90 /<. 



Pond, Mount Everett, Massachusetts, 1882. 

 According to some authors this plant might be classed with 

 DocifUum, but having no inflation at the base of the semi- 

 cells, and no plication in the cell walls, I give it a place here. 



Genus, COSMAEIUM, Corda. 



Cells oblong, cylindrical, elliptical or orbicular with margins 

 smooth, dentate or crenate; always more or less deeply con- 

 stricted in the middle ; ends rounded or truncate and entire, not 

 emarginate, lobed or sinuate ; end view oblong or oval, some- 

 times with a swelling in the middle of the longer sides ; chloro- 

 phyllous cytioplasm parietal, or more or less concentrated in the 

 center of the semi-cells, or divided into two masses ; (cytioderm 

 (cell-walls), smooth, punctate, warty, or very rarely, spinous. 

 Zygospore spherical, tuberculated or spinous, seldom smooth or 

 angular. 



The plants of this genus are recognized by their short form 

 and entire end. They are usually about IJ times as long as 

 wide ; sometimes shorter and sometimes longer, rarely over 

 two diameters in length. Ends always entire, not emarginate 

 or incised. 



