Dispora crucigenioides Printz 1914, p. 32 

 PI. 46, Figs. 5, 6 

 Characteristics as described for the genus; cells broadly ovate to 

 nearly spheroidal, 3-5/i, in diameter, 4-6/i, long; colonies 20-30/a in 

 width. 



Tychoplankter; in soft water, northern lakes. Mich. 



ELAKATOTHRIX Wille 1898, p. 302 



Gelatinous, fusiform or irregularly shaped colonies containing fusi- 

 form or ovate cells. Free-floating at least when mature. Cells with 

 either 1 or both poles acutely pointed. Chloroplast a parietal plate 

 containing 1 or 2 pyrenoids and covering almost all the wall along 

 one side. Division transverse, the daughter cells lying in pairs with 

 their longitudinal axes parallel with the axis of the colony. 



Key to the Species 



Cells small, narrow, spindle-shaped, 3-6/u in diameter, 



1 pole pointed, the other rounded _ E. gelatinosa 



Cells broadly fusiform, larger, up to 15^ in diameter, 



tapering to a point at both poles E. viridis 



Elakatothrix gelatinosa Wille 1898, p. 302 

 PI. 3, Figs. 13, 14 

 A free-floating colony of 4-16 fusiform cells with longitudinal axes 

 parallel, arranged end to end in pairs, broad at the adjoined poles, 

 tapering to a blunt point at the opposite pole. Cells 3-6/u, in diam- 

 eter, 15-25^1 long; colony 10-30/a in diameter, up to 160/a long. 

 Rare to common in various types of lakes; mostiy euplanktonic. 

 Mich., Wis. 



Elakatothrix viridis (Snow) Printz 1914, p. 31 

 PI. 4, Figs. 1, 2 

 A broadly ellipsoid colony, attached at first but later becoming 

 free-floating. Cells ovate or fusiform and arranged in pairs; dividing 

 transversely, but daughter cells with longitudinal axes at oblique 

 angles to one another. Cells 6-15/a in diameter, 35/x long. 

 Rare. Mich., Wis. 



ORDER ULOTRICHALES 



As interpreted here, this order includes unbranched, simple fila- 

 ments of mostly uniseriate cells, multiseriate in one suborder. With 

 few exceptions, the cells are cyhndrical and contain a single, band- 



t93] 



