Spirulina laxissima G. S. West 1907, p. 178 

 PI. 107, Fig. 17 



Trichomes very slender, 0.7-0.8)U, in diameter, twisted in a very 

 loose spiral, 4.5-5.3/i, wide; distance between spirals 17-22/^; apex 

 bluntly rounded. 



Euplankter. Mich. 



Spirulina major Kuetzing 1843, p. 183 

 PL 108, Fig. 11 

 Trichomes loosely spiralled, scattered among other algae, or when 

 aggregated forming a dark, blue-green mass; trichomes 1.2-1.7/* in 

 diameter; spiral 2.5-4/* wide; distance between spirals 2.7-5/*. 



This is a very active species of great length. It is commonly found 

 among Oscillatoria species on soil from which water has recently 

 subsided, or on muddy shores and margins of springs, etc. 

 Wis. 



Spirulina Nordstedtii Gomont 1892a, p. 252 

 PI. 108, Fig. 12 

 Trichomes rather closely and regularly spiralled, 2/* in diameter, 

 spiral 5/A wide, distance between spirals 5/*; cell contents pale or 

 bright blue-green. 



Plankter; also found on bottom of soft water lakes discolored by 

 humic acids. Wis. 



Spirulina princeps (West & West ) G. S. West 1907, p. 179 



PI. 108, Fig. 13 

 Trichomes loosely spiralled, either straight or bent, 3-5/* in 

 diameter; spirals 8.8-1 6/t wide; distance between spirals (9.5)-10- 

 12-(16)/*; cell contents bright blue-green, homogeneous or slightly 

 granular. 



Among other algae in tychoplankton. Wis. 



Spirulina suhsalsa Oersted 1842, p. 17 

 PI. 108, Fig. 14 

 Trichomes both closely and loosely spiralled in the same indi- 

 vidual, 1-2/1 in diameter; spiral 3-5/* wide, often so tightly coiled 

 that there is no space between the turns. 

 Tychoplankter. Wis. 



ARTHROSTIRA Stizenberger 1852, p. 32 



Trichome a long, loosely spiralled, many-celled plant, not at all 

 or only very briefly tapering toward the apex, which is broadly 



[480] 



