30 GENERA OF AhGJE. 



n. Thallus soon diffluent into shapeless mucus, 



Tetraspora, 54, or Palmella, 56 

 n. Thallus with a definite form (0). 

 o. Cylindrical or compressed, branched, 2-12 inches long; one pole 



of cells colorless Hy drums, 52 



o. Cylindrical, sometimes septate, attached at one end and spreading, 



Palmodactylon, 53 

 o. Pear-shaped, fixed by the stem-like base .... Apiocystis, 76 

 p. Chlorophyll in spiral bands (ci). 



p. Chlorophyll in two, many-rayed bodies in each cell (f). 

 p. Chlorophyll in axile plates (/). 

 q. Conjugation geniculate. Gulf States .... Sirogonium, 71 



q. Conjugation ladder-like Spirogyra, 70 



r. Conjugation ladder-like or lateral (s). 



s. Spore in one of the cells Zygnemd, 72 



s. Spore in the connective between the cells . . . Zygogonium, 73 



/. Conjugation ladder-like {u). 



t. Conjugation lateral (v). 



t. Conjugation geniculate (w). 



t. Conjugation absent, spore formed spontaneously in the cell, 



Gonatonema, 78 

 u. Spore in the connective between the cells, 



Mougeotia,i/^, or Mesocarpus, 75 



u. Spores in one of the cells Plagiospermum, 77 



V. Spore lateral, at the point of two cells . . . Pleurocarpus, 76 

 w. Spore formed at point of conjugation . . . Craterospermum, 80 

 w. Spore between the cells, quadrangular in front view, 



Siaurospermum, 79 



CLASS III. 

 § Multicellular or apparently so, filamentous (A). 

 § Unicellular, the cells sometimes clustered or in families (V). 

 A. With hair-like points (B). 



A. Without " " (C). 



B. Branched (but spuriously so) ; in small tufts . Calothrix, 8 1 

 B. Not branched; not in jelly mass; heterocysts yellow, at the base 



of the filaments; free or in small mats . . . Mastigonema, 82 



B. Not branched; in more or less firm mucilage or jelly (h). 



C. Branched; in a sheath or jelly mass (E). 

 C. Branched; not in jelly. 



C. Not branched (D). 



