486 Wisconsin Academy of Sciences , Arts , and Letters. 
S. duplex Ktz. 
Kiitzing, 1833, p. 609; Fig. 100. 
It is impossible to say just what this form is, but it is not 
a Scenedesmus. 
S. stomatomorphus (Turp.) Ktz. 
Kiitzing, 1833, p. 607. 
Achnanthes stomatomorpha. Turpin, 1820, Fig. 11. Turpin, 
1828, p. 312; PI. XIII, Fig. 10. 
Now generally recognized as Sphaerozosma stomatomor- 
phum (Turp.) Rabenhorst. 
S. moniliformis (Turp.) Ktz. 
Kiitzing, 1833, p. 607. Zanardini, 1857, p. 250. Balsamo, 1900. 
p. 266. 
Tessarthonia moniliforme. Turpin, 1820; Fig. 1. Turpin, 1828, 
p. 316; PI. XIII, Fig. 18. 
Scenodesmus moniliformis. Kiitzing, 1845, p. 139. Kiitzing, 
1849, p. 185. 
Is Cosmarium moniliforme (Turp.) Ralfs. 
Scenodesmus convergens (Ehr.) Ktz. 
Kiitzing, 1843, p. 164. 
Arthrodesmus convergens. Ehrenberg, 1838, p. 152; PI. X, 
Fig. 18. 
This is a very well recognized species of Arthrodesmus at 
the present day. 
S. duplex (Ktz.) Ralfs. 
Ralfs, 1848, p. 193; PI. XXXIV, Fig. 17A. 
Scenodesmus duplex. Archer, 1861, p. 753. 
Raphidium duplex. Kiitzing, 1845, p. 144. 
Is Ankistrodesmus falcatus var. duplex (Ktz.) G. S. West. 
This S. duplex should not be confused with the S. duplex 
described by Kiitzing in 1833. 
