Tolijpothrix conglutinata Borzi 1879, p. 371 

 PL 125, Figs. 3, 4 



Sparsely-branched filaments, closely entangled to form cottony 

 masses which adhere together by their sticky sheaths. Trichomes 

 bent and curved, with false branches arising from prostrate main 

 axes. Cells quadrate, only slightly constricted at the cross walls, 

 (7.2)-8-10;u in diameter, 3.7-5)u, long. Heterocysts ovate or globose, 

 9.2/A in diameter, 3.7-5;u, long; basal and intercalary. Sheaths wide, 

 mucilaginous, not lamellate, somewhat diffluent at the base of the 

 plant mass. Filaments 12-14^(18) [x wide. 



Although type specimens or authentically named material have 

 not been seen, the Wisconsin plants are assigned here because of 

 their close agreement with the original description of this species. 



Rare; in the tychoplankton. Wis. 



Tolijpothrix distorta Kuetzing 1843, p. 228 

 PI. 125, Figs. 5, 6 



Filaments forming cottony tufts or cushion-like expansions; tri- 

 chomes repeatedly branched, the branches spreading and flexuous, 

 or erect; cells 9-1 2/a in diameter, shorter than wide, slightly con- 

 stricted at the cross walls; heterocysts subglobose, usually solitary 

 or in series of 2-3; sheath thin, firm, not lamellate, shghtly swollen 

 at the base of the branches; filaments 10-15-(25)/a wide. 



This is a species which frequently becomes planktonic. It forms 

 macroscopic growths in many lakes. Mich., Wis. 



In our observations of material the plant seems to intergrade with 

 T. tenuis. The consistently shorter cells, however, and the average 

 greater width of the filaments in T. distorta help to separate the two. 



Tolypothrix lanata Wartmann in Rabenhorst 1858, No. 768 



PI. 125, Fig. 7 



Filaments forming cottony tufts or brownish layers. Trichomes, 

 9-13/A in diameter, repeatedly branched, the branches long and 

 flexuous. Cells quadrate to cylindric, longer than wide, 8-10/x in 

 diameter, 10-12/x long; cell contents homogeneous, blue-green. 

 Heterocysts subovate or subcyhndric; solitary or 2—3 in a series; 

 7.4 in diameter, 8-11 long. Sheaths thin and firm, sometimes 

 inflated at the base of the branches. Filaments 9— 12— (18) wide. 



This species should be compared with T. tenuis, which is a more 

 slender form. J. Schmidt (1899) redescribes the latter species and 

 includes T. lanata Wartmann. 



Common in many lakes, especially in soft or acid water. Mich., 

 Wis. 



[537] 



