WISCONSIN PHYTOPLANKTON 109 



Cells 38-41 ju, long with processes, 20-21 ix long without processes ; 

 breadth with processes 43-52 fi, without processes 17-19 fi ; breadth 

 at isthmus 10-13.5 [i. 



Carson (rrr), Devils (rrr), Whitney (r). 



This variety has considerable resemblance to 8. suhnudihrachiatum 

 in the smooth processes and their general relation to the body of the 

 cell. The variety differs, however, in the much sharper transition 

 from body to processes, more rounded semicells, smaller median con- 

 striction, parallel sides of processes, and stronger forking of the ends 

 of the processes. The general relation of process to body of semicell 

 is more like that of 8. digitahim G. S. West (Jour. Linn, Soc. Bot. 39 : 

 66, pi. 5, figs. 11-12. 1909) but the processes are totally different. 

 The forking of the processes is quite like that of 8. hrachiatum Ralfs 

 but the bodies of the semicells are different. The extent to which 

 the chloroplast extends into the processes is quite unique, since it can 

 be traced to a point beyond the forking of the processes. 



45. Staurastrum inconspicuum Nordstedt. 

 Lunds Univ. Arsskr. 9: 26, pi. 1, fig. 11. 1873. 



Cells small, length (with processes) about equal to the breadth, 

 median constriction slight, sinus semicircular, isthmus elongate and 

 broad; semicells subquadrate, with the lateral margins somewhat in- 

 flated, apex truncate and with median portion inflated, angles with 

 short hollow processes that are at first parallel to the apex of the 

 semicell and then bend upwards sharply with a knee-like joint at the 

 point of bending, ends of processes truncate ; body of cell and proc- 

 esses smooth. Vertical view quadrangular, with the sides emarginate 

 and the angles continued in straight processes that are inflated and 

 truncate at the ends. 



Zygospores unknown. 



Cells 17-26 IX long with processes, 14-15.5 jx long without processes ; 

 breadth with processes 17-26 /t; breadth at isthmus 7-9 ju, (Nord- 

 stedt.) 



Not found in the plankton of Wisconsin lakes. 



var. planctonicum var. nov. PI. 80, Figs, 5-7. 



Cells with the isthmus narrower and greatly elongate ; processes 

 longer and upward bending more pronounced ; ends of processes with 

 four minute spines. (Euplanktont.) 



Cells 26-30 /x long with processes, 17-19 fx long without processes ; 

 breadth with processes 22-30 [x, without processes 12.5 /x ; breadth at 

 isthmus 5-6 /x. 



Jag (r). 



This variety approaches the variety gracilior Maskell but has much y^^' '^ 

 slenderer processes and cell body. fy-'.^ ^ 



