or in short series; remote from the heterocysts; 10-12-(14)jli in 

 diameter and up to 70^ long. 



This species should be compared with A. oscillarioides, from 

 which it di£Fers in having spores remote from the heterocysts, which 

 are subcyhndric rather than round. The cells in A. Felisii are cylin- 

 drical, whereas those of A. oscillarioides are barrel-shaped. 



Tychoplankter. Wis. 



Anabaena jios-aquae ( Lyngb. ) De Brebisson in 



De Brebisson & Godey 1836, p. 36 



[A. Lemmermannii P. Richter] 



PI. 116, Fig. 7 



Trichomes planktonic; very flexuous and contorted, sometimes 

 coiled in an irregular spiral fashion; either solitary or entangled in 

 a twisted mass. Cells spherical to subcylindric; (4)-5-6-(8)yii in 

 diameter, 6-8-(12)/i, long; cell contents granular with conspicuous 

 pseudovacuoles. Heterocysts globose or somewhat depressed at the 

 poles; 7-9;u, in diameter, 6-10/^ long. Gonidia cylindrical or sausage- 

 shaped; solitary, or sometimes in a series, crowded near the center 

 of a tangle of filaments; usually adjacent to the heterocysts; (6)-8- 

 12-(lS)fx in diameter, (20) -24-30- (50)/. long. 



Common in the plankton of hard and semi-hard water lakes; 

 sometimes producing conspicuous water bloom growths during the 

 warm summer months, often in association with Microcystis aeru- 

 ginosa and Gloeotrichia echinulata. Mich., Wis. 



Anabaena flos-aquae var. Treleasei Bornet & Flahault 1888, p. 230 



[A. Mendotae Trelease 1889, p. 123] 



PI. 120, Fig. 2 



A variety differing from the typical by the somewhat smaller size 



of the vegetative cells and by the more slender gonidia; vegetative 



cells 4ix in diameter. Heterocysts S/x in diameter, 10/* long. Gonidia 



6fx in diameter, 40/a long. 



Forming dense water blooms. Wis. 



Anabaena helicoidea Bernard 1908, p. 52 

 PI. 116, Fig. 8 

 Trichomes free-floating; solitary or entangled in a group; spirally 

 twisted throughout their length. Cells ovate or somewhat barrel- 

 shaped, with large granules of food reserve, 3.5-3.8ju, in diameter, 

 4-5ju, long. Heterocysts globose, 5-6/a in diameter, 6ju, long. Gonidia 

 small, cylindrical, 5fi in diameter, 17jti, long. 



This species is quite similar to A. flos-aquae but is separated pri- 



[515] 



