32 WISCONSIN PHTTOPLANKTON 



MERISMOPEDIA ELEGANS A. Braun. PI. 2, Fig. 5. 



in Kiitzing, Species algarum 472. 1849; G. S. West, Brit. Freshw. Algae 348: 

 fig. 162 C . 1904. 



Colonies small or large, of 16-4000 cells regularly arranged in recti- 

 linear series and groups of four; with the cell number a multiple of 

 two in young colonies but becoming irregular in arrangement and num- 

 ber in old colonies. Colonies flat except when containing many cells. 

 Cells spherical to broadly ovoid, with homogeneous, bright blue-green 

 contents. (Facultative Planktont). 



Cells 5-7 p. broad, 5-9 /i long. 



Carson (rr), Center (rr), Green (1) (rr), Kegonsa (rr), Little Bear (rrr), 

 Mendota (r), Monona (r), Mud (1) (rr), Nancy (r), Upper Nashotah (rrr), 

 Waubesa (rr). 



This alga is a good example of a typical benthitic organism that is 

 able to thrive under limnetic conditions. It never becomes a conspicu- 

 ous member of the plankton but the colonies attain a much larger size 

 and I have observed specimens 60-70 cells broad and 60-90 cells long. 

 There is a certain amount of irregularity in such colonies so exact de- 

 terminations of cell numbers are impossible. 



var. major var. nov. PL 2, Fig. 6. 



Colonies usually containing many cells. Cell shape the same as in 

 the typical form. Cell contents homogeneous, bright blue-green. (Eu- 

 planktont) . 



Cells 10-11 n broad, 12-14 /* long. 



Beaverdam (r), Lindy (rr). 



MERISMOPEDIA GLAUCA (Ehrenberg) Nageli. PI. 2, Fig. 4. 

 Gatt. einz. Algen 55, pi. 1, fig. D 1 . 1849. 



Colonies generally containing less than 64 cells, compactly and regu- 

 larly arranged. Cells spherical to broadly ellipsoid, hemispherical for 

 some time after division. Cell contents homogeneous, generally pale 

 blue-green. (Facultative Planktont). 



Diam. cells 3-5 p.. 



George (rr), Jones (rrr), Lac Court Oreilles (rrr), Loon (rrr), Meta (rr), 

 Mill (rr), Waubesa (rr). 



This species resembles M. punctata in the size of the cells but differs 

 in the distance between the cells. 



