642 Wisconsin Academy of Sciences, Arts, and Letters. 
have found that 4-8 chloroplasts are constantly present in the 
larger cells and consider this presence of several parietal cylin¬ 
drical chloroplasts the normal condition of the vegetative cell 
and not a stage in its reproduction. The species also resembles 
0. gracilipes Lambert but only reaches the minimal dimensions 
of C. gracilpes. (Plate 11 , figs. 14 - 18 ). 
II. Browns (r), Delavan (rrr). 
Family HYDRODICTYACEAE 
Genus PEDIASTRUM Meyen 1829 
Pediastrum simplex var. duodenarium (Bailey) Rabenhorst. 
Flora Eur. Algarum 3; 72. 1868. 
Monactinus duodenarius Bailey, Smithsonian Cont. to Knowl. 7: Art. 3; 
14. pi. 1, fig. 37. 1855. 
Monactinus octonarius Baley, ibid: 14. pi. 1, f. 36. 
Pediastrum enoplon W. & G. S. West, Trans. Linn. Soc. Bot. 2nd. Ser. 
5: 81. pi. 5, figs. 1-2. 1895. 
Pediastrum elathratum var. asperum Lemmermann, Zeits. f. Fischeri u. 
d. Hilfsw. 1897: 180; Forschungsbr. a. d. Biol. Stat. zu Plon 7: 114, pi. 
2, f. 26. 
Pediastrum elathratum var. punctatum Lemmermann. Zeits. f Fischeri 
u. d. Hilfsw. 1897; 182. /. 5. 
Pediastrum simplex var. radians Lemmermann, Forschungsbr. a. d. Biol. 
Stat. zu Plon 7: 114. pi. 2, figs. 24-25. 1899. 
Pediastrum elathratum var. microporum Lemmermann, Forschungsbr. a. 
d. Biol. Stat. zu Plon 7: 114, pi. 2, figs. 29-31. 1899. 
Pediastrum elathratum var. Baileyanum Lemmermann, Forschungsbr. 
a. d. Biol. Stat. zu Plon 7: 115, PI. 2 figs. 26-28. 1899. 
Pediastrum simplex var. elathratum Chodat, Mater, p. 1. fl. crypt. Suisse 
1": 225. figs. 149A-149D. 1902. 
Pediastrum simplex var. annulatum Chodat. ihid. 225. fig. l 4 : 9 B. 
Pediastrum elathratum Yar. major Schmidle, Bot. Jahrb. f. Syst. Pflan- 
zengesch. u. Pflanzengeogr. 32: 84. pi. 3, /. 17. 1903. 
The nomenclature of- the species of Pediastrum with single 
spines is in almost hopeless confusion. West (Journ. Linn. Soc. 
Bot. 38: 135. 1907) states that ‘Gt is impossible to recognize more 
than one species, and for the specific name I have retained 
Meyen’s old name Pediastrum simplex.^^ Lemmermann (Hed- 
wigia 48: 131. 1909) takes exception to West^s statement and 
holds that according to this reasoning the forms with two pro¬ 
jections on the cell should all be grouped in one collective species. 
He recognizes four species P. simplex (Meyen) Lemmermann 
