Smith—Monograph of Scenedesmus. 439 
Var. tetradesmoides nov. var. (PL XXIX: Figs. 75-80.) 
Dimens. cell. 11 x 2.5, 12.5 x 3, 15 x 3.5, 15 x 4 g. 
The organism was isolated from a collection of algae gath¬ 
ered from the east shore of Devil’s Lake, Wisconsin. The 
cells are not as markedly lunate nor as long as those de¬ 
scribed by Lagerheim. The curve of the coenobe may be 
very slight (Fig. 75) or it may be so great that the cells form 
two parallel series (Fig. 76). All gradations between these 
two conditions can be found in my pure cultures. 
Stages similar to that shown in Figure 76 appear to be 
identical with Tetradesmus wisconsinensis Smith; the cells 
of both are about the same size, but the cultural evidence 
of both Smith and Chodat shows that the cells of T. wiscon¬ 
sinensis are always arranged in two parallel series and never 
form a flat or curved surface. This condition is compara¬ 
tively rare, however, in the form isolated since not more 
than five per cent of the colonies show a tendency toward 
an arrangement of cells in two parallel series. This variety 
is of interest from the phylogenetic standpoint since it forms 
a transition stage between Tetradesmus and Scenedesmus. 
6. S. antennatus de Breb. (PL XXVIII: Figs. 56, 58.) 
de Brebisson in Ralfs, 1848, p. 222; PL XXXV, Figs. 27A-27B. 
de Brebisson 1856, p. 412. Rabenhorst, 1868, p. 65. Cooke, 1882, 
p. 43; PL XIII, Fig. 7. Lagerheim, 1883, p. 66. de Toni, 1889B, 
p. 567. W. West, 1889A, p. 290. Roy, 1890, p. 338. W. West, 
1892A, p. 194. W. West, 1892B, p. 738. de Wildemann, 1893A. 
West and West, 1897B, p. 500. Nitardy, 1898, p. 104. Balsamo, 
1900, p. 266. West and West, 1901B, p. 119. West and West, 
1902B, p. 64. Fournier, 1903, p. 28. Nitardy, 1904, p. 318. 
Selk, 1907, p. 5. Adams, 1908, p. 35. Gutwinski, 1909, p. 435. 
Comere, 1911, p. 50. Chodat, 1913, p. 18. Brunnthaler, 1913, 
pp. 166, 170; Fig. 4. 
Scenodesmus antennatus. de Brebisson, 1856, p. 160. Archer, 
1861, p. 753. 
“Cellulis fusiformibus, 2-4-8 in seriem simplicem vel 
duplicem conjunctis, omnibus sublunulatis, plerumque ven- 
tricoses, utroque polo cuspidatis, apice globulum hyalinum 
gerentibus. Dimens. cell. 12-13 x 2.5-4 /x.” 
I am of the opinion that many of the recorders of this 
species had it confused with S. obliquus (Turp.) Ktz. In 
