WISCONSIN PHYTOPLANKTON 57 



Many juvenile spores of other species are spherical but the spores of 

 this species never become appreciably elongated. 



ANABAENA AFFINIS Lemmermann. PI. 8, Fig. 7. 

 Abh. Nat. Ver. Bremen 14: 261, pi. 1, figs. 12-13, 16-17. 1897. 



Filaments solitary, free-floating, straight or slightly flexed; with a 

 wide, homogeneous, hyaline, faintly discernible gelatinous envelope. 

 Mature vegetative cells generally spherical; rarely with homogeneous 

 contents, usually with pseudovacuoles. Heterocysts spherical. Spores 

 generally remote from heterocysts, short or elongate cylindrical, with 

 rounded ends and covered with a thick, smooth wall. (Facultative 

 planktont) . 



Cells 5-6 p. broad; heterocysts 7.5-10 ft broad; spores 9.5-12 ^ broad, 

 17-26 (i long. 



Lindy (rr), Lost (rr), North Turtle (c), Pardee (sss), Poplar (ss), Sand 

 (1) (s). 



ANABAENA LIMNETICA Gr. M. Smith. PI. 8, Fig. 8. 



Bull. Torr. Bot. Cl. 43: 481, pi. 26, fig. 27. 1916. 



Filaments free-floating, solitary, straight or slightly flexed; with a 

 copious, homogeneous, hyaline sheath. Vegetative cells spherical or 

 with poles flattened. Heterocysts spherical. Spores smooth-walled, 

 solitary, broadly ovoid, remote from or adjacent to the heterocysts. Cell 

 contents rarely homogeneous, generally with numerous pseudovacuoles. 

 (Euplanktont). 



Cells 12-15 p broad ; heterocysts 10-14 ^ broad ; spores 17-20 /* broad, 

 20-30 [ji long. 



Bear Trap (ss), Birch (1) (cc), Soft (ss), Tamarack (cc), White Ash (ss). 



ANABAENA MACROSPORA var. ROBUSTA Lemmermann. PI. 8, Fig. 6. 

 Bot. Cent. 76: 164. 1898. 



Filaments solitary, free-floating, straight or slightly bent, frequently 

 attaining a considerable length; with a copious, hyaline, homogeneous, 

 gelatinous envelope. Mature vegetative cells spherical or subspherical 

 with flattened ends. Heterocysts spherical. Spores solitary or in pairs, 

 adjacent to or remote from heterocysts, cylindrical with conical ends 

 and hexagonal in optical cross section. Spore wall smooth and thick. 

 Cells containing numerous pseudovacuoles. (Euplanktont). 



Cells 12-16 ^ broad, 9-12 ju. long ; heterocysts 12-16 /* broad ; spores 

 17-19 /* broad, 30-34 /* long. 



Camp (cc), Squirrel (ss). 





