Smith—Monograph of Scenedesmus. 
435 
524. West and West, 1895, p. 83. Schroder, 1896, p. 46. Schroder, 
1897A, p. 372. Schroder, 1897B, p. 487. Schroder, 1897C, p. 45. 
West and West, 1897B, p. 500. Schroder, 1898, p.24. Garbini, 
1899A, p. 15. Levander, 1899, p. 70. Schroder, 1899, p. 22. 
Lagerheim, 1900, p. 10. Schorler, 1900, p. 5. West and West, 
1901B, p. 119. Zykoff, 1902, p. 61. Volk, 1903, p. 104. Fink, 
1905, p. 25. Hansgirg, 1905, p. 459. Huber, 1905, p. 57. Borge, 
1907A, p. 58. Buchanan, 1907, p. 81. Migula, 1907, p. 658. 
Huber, 1908, p. 313. Collins, 1909, p. 169. Hayden, 1910, p. 44. 
“Coenobiis 4-8-cellularibus; cellulis fusiformibus, utroque 
polo acutatis, ad 35 p longis, circ. 8 p latis, in seriem sim- 
plicem (?) arctissime conjunctis, medianis rectis, extimis vel 
lateralibus extrorsum lunulatis.” 
This species is frequently considered by some a variety 
of S. ohliquus , while others consider the curving of the outer 
cells a normal variation of £. ohliquus and consequently 
unworthy of naming. Since both the curving of the terminal 
cells and the acicular shape of all cells shows a greater re¬ 
semblance to S. acuminatus (Lag.) Chod. than to S. ohliquus 
the form might more properly be placed as a variety of 
S. acuminatus , but since the cultural work shows that this 
lunate shape of the outer cells is quite characteristic, I prefer 
to consider it a distinct species. 
There is a great deal of variation in the strain of this 
species that I have isolated. The outer cells of the very 
young four-celled colonies rarely show the characteristic 
curving (Figs. 190, 195) but the erectness of the two median 
cells and the lunate character of the terminal cells is very 
pronounced in the mature colonies. (Figs. 185, 193, 194.) 
Certain of the largest colonies in the culture, however, do 
not show this curving as well but resemble S. ohliquus (Figs. 
186, 187). The arrangement of the cells in the four-celled 
colonies is always linear or sub-alternate. 
The eight-celled colonies occur as frequently as do the 
four-celled ones. The cells in the eight-celled colonies are 
always arranged in a markedly alternate series, and never 
linear. This is in direct opposition to the general view ex¬ 
pressed in previous descriptions, namely that the cells of 
the eight-celled colonies may be either in a linear or alter¬ 
nating arrangement. Although the terminal cells are lunate 
in these colonies as in the four-celled ones they do not 
