Scenedesmtis longus var. minutus G. M. Smith 1916a, p. 471 



A small variety with short spines; cells 2-3/a in diameter, 8/i, long; 

 spines 1.5-2/x long. 

 Wis. 



Scenedesmtis longus var. Naegelii (de Breb.) 



G. M. Smith 1920, p. 156 



PI. 63, Fig. 24; PL 64, Fig. 1 



Colony composed of 8 cylindrical cells arranged in a single series; 

 outer cells bearing a long, curved spine at each pole; inner cells 

 with a long spine at one pole only (rarely with no spines); cells 

 7-12/A in diameter, 16-28/i, long. 



Plankter; in several small lakes. Mich., Wis. 



Scenedesmus obliqutis (Turp.) Kuetzing 1833b, p. 609 



PI. 63, Fig. 17 



Colony composed of 2-8 (usually 4 or 8) fusiform cells arranged 

 in a single series; apices of cells apiculate; wall smooth; cells 4.2-9//. 

 in diameter, 14-18-(21)/i long. 



Rare in tychoplankton of a swamp; rare in many lakes. Mich., Wis. 



Scenedesmus opoliensis P. Richter 1896, p. 7 

 PI. 63, Fig. 18 



Colony composed of 2-4-8 naviculoid cells arranged in a single 

 series, with free walls of outer cells convex, the lateral adjoined 

 walls in contact along 1/3—2/3 of their length; apices of cells with 

 long spines (inner cells with a spine at one pole only, or some- 

 times without spines); cells S—Sfx in diameter, 14— 26/a long. 



Rare but widely distributed. Mich., Wis. 



Scenedesmus opoliensis var. contacta Prescott 1944, p. 359 



PI. 63, Figs. 19, 20 

 Colony consisting of 4 naviculoid cells arranged in a single series, 

 adjoined along % of the length of their lateral walls; spines on 

 terminal cells either 1 or 2 at each pole, long and curved; spines on 

 apices of inner cells short and straight; cells 6-8/a in diameter, 

 20-24/x long. 



Plankter; rare. Wis. 



Scenedesmus perforatus Lemmermann 1904, p. 159 

 PI. 46, Figs. 24, 25 

 Cells subrectangular with convex end walls and concave lateral 

 walls, thus forming biconvex intercellular spaces; end cells of the 



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