marily on the form of the plant, which is a loose spiral, not a 

 tangled knot. It also should be compared with A. circinalis which 

 has gonidia of quite different shape, relatively longer and larger. 

 Euplankter. Wis. 



Anabaena inaequalis ( Kuetz. ) Bornet & Flahault 1888, p. 231 

 [A. laxa (Rab.) Braun ex Bornet & Flahault 1888, p. 120] 



PI. 116, Figs. 9, 10 



Trichomes straight or slightly twisted; lying parallel and entwined 

 and inclosed by a definite sticky sheath, 7.4-8;u, wide; forming 

 gelatinous strands, entangled among other algae and adherent 

 (sometimes floating free). Cells short barrel-shaped or truncate- 

 globose, 3.7-4.2-(5);u, in diameter. Heterocysts globose or ovate, 

 4-6/x in diameter, 7.2/i, long. Gonidia cylindrical, scattered, with 

 wall often golden-brown when mature; 6-8//, in diameter, 15-16- 

 (17)/. long. 



Among other algae and floating free in marginal waters. Mich., 

 Wis. 



Anabaena lapponica Borge 1913a, p. 101 

 PI. 116, Fig. 11 



Trichomes straight, somewhat entangled; cells globose, 7.4-9.2/i, 

 in diameter; heterocysts globose, 7.4-10/x in diameter; gonidia cylin- 

 drical, ( 11.5) -13-14- ( 17)/x in diameter, 40.7-63- ( 85 )/x long, develo- 

 ping on one or both sides of the heterocysts. 



Type specimens of this plant have not been seen for confirmation, 

 but our material agrees with Borge's description. The spherical 

 shape of the vegetative cells and heterocysts separate this species 

 from A. oscillarioides, which has barrel-shaped or elongate-ovate 

 vegetative cells and heterocysts. 



Tychoplanktonic in lakes; in roadside ditches. Wis. 



Anabaena Levanderi Lemmermann 1906b, p. 536 

 PI. 117, Figs. 1, 2 

 Trichomes planktonic, solitary, straight or flexuous. Cells cylin- 

 drical, 4-6fji in diameter, 11-33/a long; constricted at the cross walls, 

 which are rounded; contents with pseudovacuoles. Heterocysts 

 spherical to ellipsoid, 6.5-8// in diameter, 6.5-9.5- (14)// long. Gon- 

 idia solitary, ellipsoid, 8—15// in diameter, 19— 45/t long. 

 Euplankter. Wis. 



Anabaena limnetica G. M. Smith 1916, p. 481 

 PI. 117, Fig. 3 

 Trichomes planktonic, solitary, straight or flexuous, inclosed by 



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