gQ WISCONSIN PHYTOPLANKTON 



var. occiDENTALE W. & G. S. West. PI. 71, Figs. 1-4. 

 Trans. Linn. Soc. 2nd. Ser. Bot. 5: 260, pi. 16, fig. 27. 1896. 



Cells somewhat smaller ; semicells narrowly elliptic and with apices 

 more flattened ; stout spines at angles as in the type ; delicate spines 

 on the face of the semicells reduced to one near each angle. Vertical 

 view with more rounded angles and margins with but two delicate 

 spines on each side of the cell ; central portion of the cell with fewer 

 and more scattered spines. (Facultative planktont.) 



Cells 41-45 [x long with spines, 32-33 /x long without spines ; breadth 

 with spines 57-63 jn, without spines 41-42 jx ; breadth of isthmus 

 11.5-12.5 /u, ; stout spines 10-12.5/1, long, slender spines 4r-9 /x long. 



Lae Court Oreilles (ss), Eeserve (rrr). 



The semicells of this variety are more compressed in the front view 

 than are those of the type. In a vertical view, aside from the more 

 rounded angles, the occurrence of only two delicate marginal spines 

 on each side is the most striking feature. In this respect the cells 

 show a great resemblance to >S^. suhteliferum Roy & Bisset, but the 

 semicells of the two are quite different in front view. 



var. PECTiNATUM W. & G. S. West. PL 71, Figs. 5-8. 

 Trans. Linn. Soc. 2nd. Ser. Bot. 5: 260, pi. 16, fig. 28. 1896. 



Cells with approximately the same shape and size as the type but 

 with longer spines. Vertical view having delicate marginal spines 

 confined to the angles and spines at the center of the cell more nu- 

 merous. (Facultative planktont.) 



Cells 56-60 ix long with spines, 45-49 ix long without spines ; breadth 

 with spines 58-66 jn, without spines 44-49 /t, breadth of isthmus 

 12,5-17 /a; length of stouter spines 6.5-12.5 /a, length slender spines 

 5-9 iJL. 



Dummy (rrr), Owen (rrr). Horseshoe (rrr). Big St. Germain (rrr). Sand (ss). 



W. & G. S. West give only a front view of this variety so that 

 determination of the variety is somewhat doubtful. 



var. BREVisPiNUM G. M. Smith. PI. 71, Figs. 9-13. 



Trans. Wis. Acad. Sci. Arts & Lett. 20: 350, pi. 11, figs. 6-8. 1922. 



Cells smaller, length and breadth about equal, sinus acute-angled 

 and with an acute apex ; semicells narrowly elliptic and with lateral 

 margins flattened; lateral margins with four stout spines that are 

 quadrately arranged and with one or two stout spines on the dorsal 

 margin just back of the lateral spines; body of semicell with two 

 transverse rows of smaller spines. Vertical view triangular, With 

 angles rounded and sides very sightly concave ; margin of cell bear- 

 ing 5-6 more delicate and shorter spines and with portion between 

 each pair of spines concave, body of cell with a second arcuate row 



