168 FRESH-WATER ALG^E OF THE UNITED STATES. 



polar vacuole often indistinct; membrane thin and close, 

 cytioplasm divides into two, or more rarely four parts. 



Diameter of cells, 4-8 //. 



Pits of rain water, often in large numbers. 

 Plate CLIV, figs. 7, 8, the normal appearance. 



CHLAMYDOMONAS HYALINA, Cohn. 



Macrogonidia oblong elliptical, ends more or less rounded, 

 thin -green, or whitish-green, anterior end furnished with 

 two long cilia. 



Diameter of macrogonidia, 14-22 ^ ; length fully equal 

 to two diameters. 



Found countless myriads in lake, Wayne County, Penn- 

 sylvania, near the shore and extending outward, giving the 

 water a thin milky-green appearance. Dipped with the 

 hollow of the hand, the motile cells were distinctly visible 

 without the aid of glasses. 



Plate CLIV, figs. 9, 10, drawn too small in comparison 

 with figs. 7, 8. 



CHLAMYDOMONAS PULVIUSCULUS, Ehrb. 



Macrogonidia ovate, nearly twice as long as broad ; deep 

 green, with a bright red lateral spot. 



Diameter of macrogonidia, 6-13 yw (Eab. ) ; 12-19 ^ long 

 (Kirchner). 



Syn. Diselmis viridis, Dujard. 



I quote this species so common throughout Europe, certain 

 it must be found here, although hitherto escaped my notice. 

 In size and form it is almost identical with Chi. hyalina, but 

 deep green in color and possesses a distinct red, lateral pig- 

 ment spot. 



Plate CLV, figs. 23, 24, a usual appearance of this species, 

 the latter a zoospore indicating much activity by means of 

 two cilia ; fig. 25, an encysted form divided into two ; figs. 

 26, 27, a similar form divided into four parts ; fig. 28, cell 

 divided, forming new encysted cells ; fig. 29, two red resting 

 cells ; fig. 30, a macrozoospore, contents dividing ; fig. 31, 

 a cell with contents divided ; parts escaping as microzoo- 

 gonidia. 



