58 



WISCONSIN PHYTOPLANKTON 



semicell; typically with one pyrenoid in each chloroplast. (Tycho- 



planktont.) 



Zygospores spherical, bearing numerous long delicate spines with 

 conical bases and bifurcate apices (W. & G. S. West.) 



Cells 79-102)11 long with spines, 50-65 /x without spines; breadth 

 of cells 80-96 /x with spines, 50-56 jit without spines; isthmus 14^19/* 

 broad ; spines 15-22.5 fx long. 



Zygospores 45-58 ju, in diameter without spines, 80-98 ix with spines 

 (W. &G. S. West). 



Carroll (rrr), Des Moines (rrr), Jag (rrr), Eiee (rrr). 



var. POLYMAZUM Nordstedt. PI. 65, Figs. 7-9. 

 Lunds Univ. Arsskr. 9: 38, pi. 1, fig. 20. 1873. 



Cells with angles more rounded than the type, polar spines sub- 

 erect (very rarely divergent.) Central area smooth but with an arc 

 of emarginate to arcuate verrucae just below the semicell apex. Ver- 

 tical view oblong-elliptic, with poles strongly emarginate. (Faculta- 

 tive planktont.) 



Cells 70-88 /x long with spines, 52-58 fi long without spines ; 73-86 n 

 broad with spines, 52-56 /x broad without spines; isthmus 15-17/* 

 broad ; spines 10-15 /i long. 



Beaverdam (ss), Carson (rrr), Cranberry (rrr), Crooked (rrr), Fish (rrr), 

 Found (rr), George (rr), Hill (rr), Horseshoe (rr), Lake of the Woods (rrr), 

 Lindy (rr), Lost (rrr), Lynx (rrr), Meta (rrr), Middle McKenzie (rrr), Nica- 

 boyne (rr), Sand (rrr), Sanford (rrr), Speese (rrr). 



The cells of this variety have more rounded angles than the type 

 and as a result a much plumper appearance. The vertical view is 

 also different since the poles are emarginate instead of broadly 

 rounded. The chief feature of the variety, however, is the subapical 

 arc of verrucae. The number and shape of these verrucae varies 

 greatly and in certain specimens there is a double arc of verrucae. 



The variety is widely distributed in Wisconsin lakes but never 

 occurs in large quantities. 



var. MiNNEAPOLiENSE Wollc. PI. 65, Figs. 10-11. 



Bull. Torr. Bot. CI. 11: 16. 1884; Desm. U. S. 94, pi. 52, fig. 16. 1884; W. & 

 G. S. West, Trans. Linn. Soe. 2nd. Ser. Bot. 5: 252, text fig. 2. 1896. 



Cell shape and arrangement of spines as in the variety polymazum; 

 subapical verrucae generally arranged in an arc, rarely in an elliptical 

 ring, with a small erect spine above or below the verrucae. (Tycho- 

 planktont.) 



Cells 78-82 fi long with spines, 50-58 /x long without spmes ; 79-83 fi 

 broad with spines, 52-55 fx broad without spines ; isthmus 16-17.5 /* 

 broad ; spines 12.5-15 ju, long. 



Bass (rr). Diamond (rrr). Horseshoe (rrr), Jenny (rr), Little Doetor (rrr), 

 Meta (rrr), Eiee (rr). 



