A Key to the More Frequently Occurring Freshwater Algae - Freshwater Algae: Identification, Enumeration and Use as Bioindicators - page 227

1

3

2a 2b

4a

4b

5a 5b

7

6a 6b

8a 8b

Plate XXV 1 . Didymosphenia. 2 . Gomphonema :(a) G. augur frustule markings, (b) G. acuminatum chloroplast
arrangement. 3 . Epithemia. 4 . Achnanthes : (a) valve view, (b) girdle view, chloroplast. 5 . Tetracyclus : (a) valve view,
(b) girdle view. 6 . Diatoma hyemalis : (a) valve view, (b) girdle view. 7 . Diatoma vulgaris. 8. Fragilariaforma : (a) valve
view. (b) girdle view.