Smith—Monograph of Scenedesmus. 
471 
of the coenobe only; so that the distinction between S. longus 
and S. quadricauda is very sharp. 
The occurrence and number of spines on the median cells 
of the colony, however, is quite variable. Spines may occur 
on both poles of every cell in the colony (Fig. 157) or not 
(Fig. 156). Again there may be more than one spine at each 
pole of a cell, this cell being either terminal or median (Fig. 
158). 
GEOGRAPHICAL DISTRIBUTION 
EUROPE. Austria-Hungary (Brunnthaler, 1907; Hansgirg, 
1886; 1890B, 1892A, 1892B, 1905; Pascher, 1903; Riabinine, 
1889A, 1889B). England (Fritsch, 1902; G. S. West, 1904B). 
Germany (Honigman, 1909; Kirchner, 1878; Lemmermann, 1893; 
Meyen, 1829; Schorler, 1900; Selk, 1907; Volk, 1903, 1905). 
Italy (Gugliemetti, 1910). Roumania (Teodoresco, 1907). Russia 
(Dorogoslaisky, 1904; Gutwinski, 1891). Scotland (West and 
West, 1909B). Sweden (Lagerheim, 1883; Borge, 1895). Switzer¬ 
land (Chodat, 1902). 
ASIA AND OCEANIA. Australia (Borge, 1911). 
AMERICAS. Canada (Borge, 1909). Pategonia (Borge, 
1901B). United States (Borge, 1909; Collins, 1909; Conn and 
Webster, 1908; Snow, 1903; Wolle, 1887). 
POLAR AND SUB-POLAR REGIONS. Faeroes. (Boergesen, 
1899B, 1901A). 
Var. brevispina nov. var. (PL XXXI: Figs. 151-155.) 
Cellulae longiores atque angustiores. Aculei breviores. 
Dimens. cell. 9x3, 9x4, 11x4, 11x4.5, 11x5 p. Long, 
acul. 2 p. 
This variety differs from the foregoing in that the cells are 
longer and narrower with shorter spines, which are rarely 
absent from the median cells. The shortness of the spines 
suggests S. denticulatus Lag., but since they are not broad at 
the base this form is classed with S. longus instead of S. 
denticulatus. 
Var. minutusnov. var. (PI. XXXI: Figs. 147-150.) 
Cellulis oblongi-ovalis longitudinibus circiter 2.5-plo 
latitudinibus. Aculei breves. Dimens. cell. 6.5 x 2, 7x2, 
7 x 3, 8 x 3 p. Long acul. 1.5-2 p. 
The largest cells found in pure cultures of this form do 
not reach the minimal size of the other varieties. The spines 
