WISCONSIN PHTTOPLANKTON 43 



one another. Individual cell sheaths confluent with the colonial en- 

 velope. Cell contents homogeneous, grey to pale blue-green. (Tycho- 

 planktont). 



Diam. cells 3.5-4.5 /*. 



Beaver (r), Beaverdam (sss), Harris (rrr), Lac Court Oreilles (ss), Win- 

 nebago (rr). 



APHANOCAPSA GREVILLEI (Hassall) Rabenhorst. PI. 3, Fig. 1. 



Flora Eur. Algarum 2: 50. 1865; G. S. West, Brit. Freshw. Algae, 351, fig. 

 165 A . 1904. 



Colonies free-floating or sessile ; spherical to ellipsoid when free-float- 

 ing, dirty green in color. Cells spherical, solitary or in pairs and some- 

 what crowded. Cell contents homogeneous or finely granulose, bright 

 blue-green in color. (Facultative Planktont). 



Diam. cells 3.5-5 p.. 



Beaverdam (rr), Birch (ss), Camp (ss), Chetac (sss), Muskallonge (rr), 

 Rice (1) (rr), Silver (1) (rrr), Whitefish (ss). 



APHANOCAPSA RIVULARIS (Carm.) Rabenhorst. PI. 3, Fig. 2. 



Flora Eur. Algarum 2: 49. 1865; Cooke, Brit. Freshw. Algae 210, pi. 86, fig. 2. 

 1884. 



Colonies free-floating or sessile ; spherical, tubular, or irregular in 

 shape. Cells spherical, solitary or in pairs and some distance from one 

 another Avithin the colony. Individual sheaths of cells confluent with 

 the hyaline, homogeneous, colonial envelope. Cell contents homogene- 

 ous or finely granulose; bright blue-green in color. (Tychoplanktont). 



Diam. cells 5-6 //.. 



Star (rrr). 



APHANOTHECE Nageli 1849. 



Colonies free-floating, sessile, or endophytic; spherical or expanded 

 into amorphous masses and enclosed by a firm, copious, homogeneous, 

 hyaline or colored envelope. Cells oblong to cylindrical, with rounded 

 ends. Cells forming a solid mass distributed throughout the colonial 

 envelope but lying some distance from one another. Individual cell 

 sheaths indistinct, confluent with the colonial envelope. Cell contents 

 homogeneous or finely granulose, never with pseudovacuoles ; grey, light 

 to bright blue-green, or olive-green in color. 



Reproduction by vegetative division of cells in three planes, but with 

 cell divisions always taking place at right angles to the long axes of 

 cells. 



