76 WISCONSIN PHYTOPLANKTON 



Adelaide (r), Bass (rr). Little Bass (rrr), Bear (rrr), Crooked (sss), Devils 

 (rrr), Diamond (r), Duck (rrr), Dummy (sss), Grindstone (rrr), Jenny (rr), 

 Jones (rrr), Lac Court Oreilles (ss), Lindy (rr). Lynx (rr), Nicaboyne (rrr), 

 Reserve (sss), Sanford (rrr). Tank (rrr), Turtle (rr), Whitefish (cc). 



The species should be compared with ^S'. dejectum De Brebisson, 

 S. Dickiei Ealfs, and S. curvatum W. West. It differs from all of 

 them in the stouter spines at the angles, in size and in shape of the 

 cells. Lundell states that there are both triangular and quadrangular 

 members of the species but I have observed the triangular specimens 

 only in the plankton of Wisconsin lakes. 



var. scoTicuM W. & G. S. West. PI. 69, Figs. 22-24; PI. 70, Figs. 1-2. 



Jour. Linn. Soc. Bot. 35: 544, pi 16, fig. 8. 1903. 



S. megacanthum forma Borge, Bot. Not. 1897: 213, pL 3, fig. 7. 1897. 



Sinus subrectangular to obtuse-angled, isthmus proportionally nar- 

 rower; apices of semicells generally concave, rarely straight; spines 

 at angles longer and always divergent. Vertical view with sides of 

 cells more retuse. (Euplanktont.) 



Cells 47-54 /a long with spines, 36-38 fi long without spines, breadth 

 67-82 /x with spines, 40-46 /x without spines; isthmus 8-10 /x broad; 

 spines 20-25 /x long. 



Bass (sss), Diamond (r), Horseshoe (rr), Jones (r). Little Doctor (rrr), 

 Meta (rr), Shell (c). 



The variety is more graceful than the type and differs in having 

 concave apices of the semicells and longer spines. 



15. Staurastrum Dickiei Ralfs. 



Brit. Desm. 123, pi. 21, figs. 3A-3B. 1848; W. West, Jour. Linn. Soe. Bot. 29: 

 171. 1892; G. S. West, Brit. Freshw. Algae 141, figs. 52A-52C. 1904. 



Cells fairly small, breadth (with spines) about one and a quarter 

 times the length, deeply constricted, sinus sublinear, opening out- 

 wards and with an acute apex, isthmus narrow ; semicells transversely 

 elliptic, the dorsal margin somewhat more tumid than the ventral 

 margin, angles furnished with a single short stout acute spine, spines 

 strongly convergent. Vertical view triangular, with sides of cells 

 somewhat retuse and angles rounded and furnished with a short stout 

 straight spine. Cell wall smooth. 



Zygospores spherical, clothed with fairly numerous straight spines 

 with acutely pointed apices (G. S. West). 



Cells 35 /x long ; breadth with spines 42 /t, without spines 29 /a ; 

 isthmus 6 ju, broad (W. West). 



Not found in the plankton of Wisconsin lakes. 



var. MAXIMUM W. & G. S. West. PI. 70, Figs. 3-5. 



Trans. Linn. Soc. 2nd. Ser. Bot. 5: 72, pi. 8, fig. 19. 1895; ibid. 255, pi. 18, 

 fig. 13. 1896. 



