WISCONSIN PHYTOPLANKTON 107 



KEY TO THE SPECIES. 



Groups with cells quadrate or pyramidate W. BOTRYOIDES 



Groups with cells in a linear series W. LINEABIS 



WESTELLA BOTRYOIDES (W. West) de Wildeman. PI. 21, Fig. 4. 



Bull. Herb. Boiss. 5: 532. 1897. 



Tetracoccus botryoides W. West, Jour. Roy. Micr. Soc. 1892: 735, pi. 10, 

 figs. 43-48. 1892. 



Colonies irregularly shaped, without a gelatinous envelope, generally 

 containing 40-80 cells. Cells spherical, pyramidately or quadrately 

 arranged in groups of four (rarely eight). Chloroplast single, cup- 

 shaped or entirely filling the cell; with or without a pyrenoid. (Facul- 

 tative Planktont). 



Diam. cells 3-9 /*,. 



Blake (rrr), Fishtrap (rr), Hillman (rrr), Horse (rrr), Horseshoe (1) (rr), 



Jag (r), Little Bass (2) (rr), Little Butternut (rrr), Little Crooked (rr), 



Mendota (rrr), Mill (rrr), Nancy (rr), Pine Tree (rr), Round (3) (rr), 

 Sishebogema (rr). 



var. MAJOR Gr. M. Smith. 

 Trans. Wis. Acad. Sci., Arts, & Lett. 19 1 : 628. 1918. 



Cells larger than the typical form, otherwise the same. 

 Diam. cells 8-13 p. 



Whitefish (rr). 



Westella linearis sp. nov. PI. 21, Figs. 2-3. 



Colonies of irregular shape, rarely containing more than 40 cells. 

 Cells spherical, always in groups of four and arranged in a linear 

 series. Remains of old mother cell walls that hold the colony together 

 very inconspicuous. Colony without a gelatinous envelope. Chloro- 

 plast single, parietal, without a pyrenoid. (Euplanktont ?). 



Diam. cells 3-6 //,. 



Pine Tree (rr). 



In the arrangement of the cells this species is quite unlike the other 

 members of the genus but since the cells are in groups of four that are 

 held together by the remains of old mother cell walls it seems better 

 to place it in this genus than in Crucigenia. 



