COSMARIUM. 67 



rather the two cells into which it first divides, remaining in 

 the center of the group." Wood, p. 35. 



I would suggest this to be very near, or identical with C. 

 tinctum, Ralfs. 



C. TINCTUM, Ealfs. ( Sphaerozosma tinctum, Eah.) Plate XIX, 



fig. 31. 



Cells small, somewhat longer than broad ; isthmus broad, 

 constriction outwardly enlarged; semi-cells oval ; chlorophyl 

 a single mass ; cytioderm smooth, often tinted with yellow, 

 brown or red. 



Diameter 10-15 ;/. 



Of the sporangium, Ralfs writes, " It is large in proportion 

 to the cells, and quadrate with an empty segment of the 

 fronds permanently attached at each corner. Sometimes the 

 fronds couple in a crossed position, when the sporangium 

 appears variously twisted or distorted." 



I find single specimens of this plant occasionally, but have 

 not had a satisfactory group of them, or fruiting specimens. 



C. TUMIDUM, Lund. Plate XVIII, fig. 23 ; Plate XXI, fig. 20. 



Cells somewhat longer than broad, constriction narrow 

 linear. Semi -cells suboval, rather flat base, apex broad con- 

 vex, with one chlorophyllous mass. Cytioderm punctate 

 and more or less granularly rough in the central part, margin 

 smooth. Plate XXI, fig. 20, appears to be a variety of 

 this form, coarsely granular. 



Diameter 20-33 jw. 



Pennsylvania, New Jersey, etc. 



In front view this species bears some resemblance to C. 

 Phaseolus, Breb., but differs in being proportionately longer, 

 and in not having the base of the semi-cells reniform, and in 

 not having an entirely smooth membrane. Some specimens 

 are very distinctly punctate, others not so evidently except 

 away from the margins. Kirchner makes two varieties : 

 a. genuinum, cytioderm distinctly granular in the middle; b. 

 subtile, cytioderm finely punctate over the whole cell. 



C. INFLATUM, Wolle. Plate XLVIII, figs. 18, 19. 



Cells one-half longer than broad; semi cells gradually en- 

 larged from a narrow base to a broadly dilated end ; end 

 view broadly elliptic; lateral view circular, with somewhat 

 flattened sides ; membrane finely punctate or smooth. 

 Diameter 25-28 n. ; length about 40 //. 

 Ponds, Minnesota. 



