Smith—Monograph of Scenedesmus. 
437 
plane of the other cells, which are more often sigmoid than 
lunate. The terminal cells of the four-celled colonies show 
at times the same relationship to the colony as do the ter¬ 
minal cells of the eight-celled colonies (Figs. 203, 208) but 
at other times all the cells are in the same plane (Figs. 206, 
209). The two median cells in these colonies come in con¬ 
tact with each other only in the middle portion but join the 
terminal cells by their apices. 
The objection to recognizing this material as a distinct species 
might be raised on the grounds that the extreme polymorphism of 
S. obliquus has created a Dadylococcus stage and not a distinct 
species. The question of the Dadylococcus stage of S. obliquus 
has already been discussed. The fact that the cells in the cultures 
of S. Bernardii are always grouped definitely in twos, fours, or 
eights shows that we are dealing with a definitely organized coenobe 
and not an irregular branching system. There is also the further 
evidence that S. obliquus and S. Bernardii both retain their 
identity when grown under the same conditions of light, tempera¬ 
ture, and chemical environment. 
5. S. acuminatus (Lag.) Chodat (PI. XXV: Figs. 3—5). 
Chodat, 1902, p. 211. Lemmermann, 1904A, p. 40. Lemmer- 
mann, 1904G, p. 159. Hansgirg, 1905, p. 459. Lemmermann, 1905B, 
p. 158. Reinhardt, 1905, p. 26. Volk, 1905, p. 64. Lemmermann, 
1907B, p. 411. Brunnthaler, 1907, p. 207. Schorler, 1907, p. 356. 
Selk, 1907, pp. 5, 57, 61, 64, 68, 73, 78, 79, 85, 91, 94, 98, 99, 
103, 108, 112, 115. Tanner-Fullmann, 1907, pp. 122, 125, 132. 
Bachmann, 1908, p. 44. Bernard, 1908, p. 183; PI. XIV, Fig. 
422. Kolkowitz und Marsson, 1908, p. 93, 120. Marsson, 1909, 
pp. 547, 557, 559, 561. Marsson, 1911, p. 261, 263, 266, 275, 282, 
285. Petersen, 1911, p. 160; Fig. 5. Conrad et Kufferath, 1912, 
p. 321. Brunnthaler, 1913, p. 165, 170; Fig. 2. Chodat, 1913, 
p. 22. 
Selenastrum acuminatum Lagerheim, 1883, p. 71; PI. Ill, Figs. 
27-30. de Toni, 1889B, p. 596. Turner, 1892, p. 162; PI. 
XX, Fig. 30. Marsson, 1901B, p. 96. Marsson, 1904, p. 146. 
Marsson, 1908B, p. 107, 111. Marsson, 1908A, p. 32, 40. £. 
obliquus var. acuminatus Playfair, 1912, p. 518, PI. LVI, Fig. 8. 
S. falcatus Chodat, 1894, p. 625. de Wildemann, 1897A, p. 60. 
Chodat, 1900, p. 3. Chodat, 1901, p. 1309. Tanner-Fullmann, 
1906, p. 158. Tanner-Fullmann, 1907, pp. 124, 125. S. acuminatus 
var. biseriatus Reinhardt, 1905, p. 26. 
“*S. familiis e cellulis quaternis constitutis, cellulis arcuatis 
vel falcatis, apicibus acuminatis; apicibus cellularum adul~ 
