Smith—Monograph of Scenedesmus. 
427 
C. Cells with longitudinal ridges and spines at 
poles of terminal cells. 
a. Cells with spines on end cells. 
17. S. armatus (Chod) nov. comb. 
b. Cells with spines on end cells and teeth on 
poles of all cells. 
18. S. carinatus (Lemm.) Chodat. 
4. Short spines or granulations in the middle portion of 
cell wall as well as on the ends. 
A. Spines or granulations completely covering the 
cell wall. 
X. Cells without long horns at poles of ter¬ 
minal cells. 
19. S. hystrix Lag. 
X. Cells with long horns on poles of terminal 
cells, interstices between cells. 
20. S. ornatus (Lemm.) nov. comb. 
XXX. Spines on ends of all cells. 
21. S. insignis (West and West) Chod. 
B. Spines or granulations in rows on sides of cells. 
a. 3-4 rows of granulations from pole to pole on 
each cell. 
22. S. granulatus West and West. 
b. Two rows of spines from pole to pole on me¬ 
dian cells, one row on terminal cells. Teeth 
on poles. 
23. S. serratus (Corda) Bohl. 
5. Cells without external ornamentation aside from 
long horns. 
A. Spines on both median and terminal cells. 
a. Spines on middle part of cell wall as well as on 
poles. 
24. S. abundans (Kirch.) Chod. 
b. Spines only on poles of all cells. 
25. X longus Meyen. 
B. Spines on ends of terminal cells only. 
a. Colonies without linear interstices between cells. 
X. Ends of cells rounded, cells in lateral con¬ 
tact entire length. 
