86 WISCONSIN PHYTOPLANKTON 



Cells 37-65 ja long with processes, 25-35 jx long without processes ; 

 breadth with processes 57-88 /x ; without processes 18-25 /x ; breadth at 

 isthmus 7.5-11 /x. 



Big Bass (sss), Beaverdam (rrr), Bettine (rrr), Carroll (sss), Clare (rr), 

 Clear Crooked (rr), Crab (ss), Cranberry (r), Crawling Stone (ss), Devils (rrr), 

 George (rrr). Granite (rrr), Horseshoe (rrr), Jenny (rrr), Lac du Flambeau 

 (rrr), Little Rice (sss). Long (rrr), Lost (rrr), Middle MeKenzie (rrr). Pine 

 (rrr), Rice (rr), Red Bass (rrr), Sand (rrr), Shell (sss). South Crab (rrr), 

 Tenderfoot (rrr), Tied Canoe (rrr), Travis (ss). 



Although the genus Staiirastrum was based upon this species and 

 many observers have recorded it, the specific limits are poorly defined, 

 even at the present day. After examining plankton material from 

 many European and American lakes I have reached the conclusion 

 that the essential characters are the relatively long and divergent 

 processes and an absence of a row of verrucae just within and parallel 

 to the margin of the cell body in a vertical view of the cell. 



Staurastrum gracile Ralfs is an alga that is exceedingly difficult to 

 separate from ;S^. paradoxum but S. gracile usually has shorter sub- 

 parallel processes and always a row of emarginate verrucae just within 

 the lateral margins in a vertical view of the cell. S. paradoxum is 

 subject to considerable variation in size and degree of divergence of 

 the processes. Under plankton conditions the granulation becomes 

 more pronounced, the granules at times becoming very short spines, 

 while the terminal spines of the processes are also much larger. The 

 present practice among phycologists is not to attempt a naming of the 

 various forms of the species as it is found in the plankton. 



var. LONGiPES Nordstedt. PI. 73, Figs. 3-6. 



Lunds Univ. Arsskr. 9: 35, pi. 1, jig. 17. 1873; W. & G. S. West, Trans. Roy. 

 Soc. Edinburgh 41: 504, pi. 7, -fig. 13. 1905. 



Semicells cyathiform, with apices flattened; angles continued in 

 very long graceful upwardly turned processes with finely crenulate 

 margins and terminating in four divergent spines; cell body smooth 

 and without ornamentation. Vertical view triangular, with the sides 

 of the body of the cell concave and the processes with the same ap- 

 pearance as in the front view. (Euplanktont.) 



Cells 67-108 /x long with processes, 22-28 jn long without processes ; 

 breadth with processes 67-114 /,<,, without processes 18-22 jx ; breadth 

 at isthmus 7.5-9 /x. 



Little Bass (rr). Bear Trap (rr). Camp (rr). Center (sss), Chetek (rr). Devils 

 (sss), Dummy (ss). Fowler (rr), Granite (ss). Hill (rrr). Hooker (rr), Lac 

 la Belle (rrr). Mud (r), Nancy (s), Red Bass (rrr), Round (rr). Big St. Ger- 

 main (rrr). Shell (rrr), Sishebogema (rrr), Speese (rrr), Two Sisters (rr), 

 Trout (rr), Vermilion (r), Whitefish (ss). 



The great length of the processes in proportion to the length of the 

 cell body is the most striking feature of this variety. There is con- 



