IOWA ACADEMY OF SCIENCE 
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Cells elongate and acutely attenuated, often lunate, solitary or loosely grouped 
in irregular bundles. Cells of moderate length, usually with not more than 
one pyrenoid .2; Ankistrodesmus 
1 . Scenedesmus. 
KEY TO THE SPECIES. 
Cells obtuse rounded at each pole. 
No cells with hairs or spines. .S. bijugatus 
Terminal cell with a hair on each pole. .S. quadricauda 
Cells usually acute at both ends. ....£?. obliquus-— S. obliquus dimorphus 
168. S. bijugatus (Turp.) Kuetz. 
Eagle Grove. Slough, amid Utricularia. Buchanan. 
169. S. quadricauda (Turp.) Breb. 
Fayette. Fink. 
Grinnell. Fink. 
Ames. Bessey. 
170. S. quadricauda var. abundans. 
Fayette. Fink. 
Grinnell. Fink. 
171. S. obliquus Kuetz. 
Fayette. Fink. 
Grinnell. Fink. 
Ames. Aquarium. Buchanan. 
172. S. obliquus var. dimorphus Rabenh. 
Fayette. Fink. 
Grinnell. Fink. 
Aquarium, Ames. With peat from northern Iowa. Buchanan. 
2. Ankistrodesmus ( Rhaphidium ). 
' KEY TO THE SPECIES. 
Cells 16-24 times as long as broad. 
Chloroplast without pyrenoid. .A. falcatus 
Chloroplast with pyrenoid. .A. falcatus aciculare 
Cells 3-6 times as long as broad. .A. convolutus 
173. A. falcatus (Corda) Ralfs (R. polymorphum) . 
Fayette. Fink. 
Grinnell. Fink. 
17 U. A falcatus var. acicularis (A. Br.) West. 
Fayette. Fink. 
Boone. Horse trough. Buchanan. 
Eagle Grove. Slough. Buchanan. 
175. A. convolutus (Rabenh.) West. 
Fayette. Fink. 
Subfamily II. 
Oocystideae. 
1. Palmellococcus. 
176. P. miniatus (Kuetz.) Chodat. 
Ames. Under limestone arch, College. Buchanan. 
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