plast covering the entire lateral walls, but narrow, ring-like, and 

 zonate immediately following cell division. Cells 4-8/x in diameter; 

 filament ( including sheath ) 8-18/x in diameter. 



This species often appears in the tychoplankton of acid lakes and 

 in small pools of Sphagnum bogs. Mich., Wis. 



Geminella mutabilis (de Breb.) Wille 1911, p. 72 



PI. 6, Fig. 16 



Uniseriate filaments of broadly ovate, spheroidal, or cylindrical 



cells, almost equally separated from one another, but with daughter 



cells remaining in approximation. Chloroplast completely covering 



the cell wall. Cells 9-13-(20)(U in diameter. 



InteiTningled with other algae in shallow water of small lakes and 

 swamps. Wis. 



Geminella ordinata (West & West) Heering 1914, p. 41 



PI. 24, Fig. 9 



Uniseriate filaments of oblong-ellipsoid cells, arranged in an inter- 

 rupted series, separated from each other by a distance of a cell's 

 length or more. Chloroplast solitary, extending completely around 

 the wall. Cells 5-5.8/x in diameter. 



Intermingled with other algae in shallow water of lakes and ponds. 

 Wis. 



HORMIDIOPSIS Heering 1914, p. 50 



Filaments short, composed of from 5 to 20 cells, arranged in con- 

 tinuous or interrupted linear series. Cells ovoid, cylindric, or trans- 

 versely ellipsoid, inclosed by a gelatinous sheath. Chloroplast a 

 parietal, incomplete band, without a pyrenoid (or with 1 ?). Oil 

 formed as a food reserve. Reproduction by zoospores or gametes 

 unknown. 



Hormidiopsis ellipsoideum Prescott 1944, p. 350 

 PI. 7, Figs. 1, 2 



Cells transversely elliptic, arranged in linear series in groups of 4, 

 each group inclosed by a wide, hyaline, and homogeneous gelatinous 

 sheath. Chloroplast a parietal band as wide as the cell but not en- 

 tirely encircling the wall; with 1 pyrenoid. Cells 8/x in diameter, 

 5.5/i, long; filament 14.8|U, wide. 



Although this plant was found in only one collection it appeared 

 distinctive enough to be worthy of description. Hormidiopsis is a 

 little-understood genus, apparently containing but one other species, 

 H. crenulata Heering. To this genus, Heering has also assigned ques- 



[101] 



