WISCONSIN PHYTOPLANKTON 85 



visible in a front view) just above the isthmus; apex of semicells flat- 

 tened or slightly tumid, with processes arising just below the apex, 

 processes slightly attenuated and upwardly curved, terminating in 

 three minute divergent spines ; apical portion of semicells and processes 

 covered with minute spines that are generally scattered but at times 

 arranged in concentric rings near the point of juncture of cell body 

 and process. Vertical view triangular, with the angles continued in 

 long straight processes whose ornamentation appears the same as in 

 a front view; central portion of body of the cell without spines. 

 (Euplanktont.) 



Zygospores unknown. 



Cells 60-100 iM long with processes, 35-45 fi long without processes ; 

 breadth with processes 65-105 ju., without processes 18-30 [x ; breadth at 

 isthmus 9-11.5 (i. 



Balsam (rrr), Bear (r), Beaverdam (ss), Bloom (rr), Crawling Stone (rrr). 

 Deer (rrr), Dummy (ss), Found (r), Granite (ss). Half Moon (r), Little Bear 

 (rrr), Lost (r), Mercer (rrr), Meta (rr). Mud (rr), Pokegama (rr), Sand (sss), 

 Sishebogema (ss), Two Sisters (rr), Wapagossett (rr), Whitefish (r). 



Since this differs from S. paradoxum Meyen in the cylindrical body 

 of the semicells, the nature of the sinus, and the slender upwardly 

 curved processes as well as in the basal ring of spines it seems better 

 to consider this a distinct species and not a variety of S. paradoxum. 

 It should also be compared with 8. longiradiatum W. & G. S. West. 



25. Staueastrum paradoxum Meyen. PI. 72, Figs. 15-22; PI. 73, 



Figs. 1-2. 



Nova Acta Phys. Med. Ac. Caes.-Leop. Nat. Cur. 14=^: 777, pi. 43, figs. 37-38. 

 1829; Kalfs, Brit. Desm. 138, pi. 23, iigs. 8A-8F. 1848; Eoy & Bisset, Ann. 

 Scottish Nat. Hist. 1893: 241. 1893; W. & G. S. West, Jour. Linn. Soc. Bot. 35: 

 548, pi. 18, -figs. 4-5. 1903; Trans. Bot. Soc. Edinburgh 23: 27, pi. 2, -figs. 33-35. 

 1905. 



Cells of medium size, length somewhat greater than the breadth 

 (without processes), median constriction fairly deep, sinus widely 

 open and with an acute apex, isthmus fairly narrow; semicells ob- 

 versely triangular to subcampanulate, with the dorsal margin flat- 

 tened to slightly convex ; angles continued in long somewhat attenu- 

 ated processes that terminate in truncate ends that are tri- or quad- 

 rispinate ; processes always divergent but the degree of divergence ex- 

 ceedingly variable; body of semicell with scattered granules and 

 processes with concentric rings of granules. Vertical view triangular, 

 with the angles continued in processes whose length is at least equal 

 to the diameter of the cell body ; central area of body of the cell with 

 scattered granules or with the granules confined to the marginal re- 

 gion; processes with concentric rings of granules. Chloroplast axial, 

 with a bilobed process running to each angle of the semicell; pyre- 

 noid single and central. (Facultative planktont.) 



Zygospores spherical, with a few long spines that terminate in 

 bifurcate or trifurcate apices (Roy and Bisset.) 



