32 WISCONSIN PHYTOPLANKTON 



SO that the symmetrical arrangement of three pairs of spines at each 

 angle is not found in every case. 



21. Staurastnim spiculiferum sp. nov. PI. 71, Figs. 16-20. 



Cells fairly small, length (without spines) slightly greater than 

 the breadth, deeply constricted, sinus acute-angled and with an acute 

 apex, isthmus narrow; semicells hexagonal-rectangular, with the dor- 

 sal margin subconvex to subconcave ; lateral angles broadly truncate 

 and with the truncate faces somewhat convergent towards the isthmus ; 

 semicells ornamented with delicate spines of two different lengths, 

 superior and inferior angles of lateral margin with a single long spine, 

 the two spines diverging, cell apex with a shorter spine within each 

 lateral margin and face of semicells with a similar spine near each 

 lateral margin. Vertical view triangular, median portion of the sides 

 with a slight truncate elevation; angles subrectangular and bearing 

 two long straight spines that lie in the same vertical plane, cell margins 

 with a single short vertical spine near each angle and two similar short 

 spines within each angle. Cell wall finely punctate. (Euplanktont.) 



Zygospores unknown. 



Cells 29-45 fi long with spines, 23-25 [x long without spines ; breadth 

 with spines 30-40 ju, without spines 20-24 ;li; breadth at isthmus 

 6.5-8,5 fx ; length of spines at angles 5-12.5 /x, length interior spines 

 3.5-5 (I. 



Pine Tree (r). Long (rr). 



In the shape of the cell the species has a certain resemblance to 

 8. quadrangulare De Brebisson but the spines are much too fine for 

 the alga to be considered a variety of 8. quadrangulare. In the spines 

 of two sizes, as well as in the arrangement of the spines it resembles 

 8. minnesotense Wolle, but the shape of the cells and the sizes of the 

 two algae are quite different. 



The spines of the alga in the specimens from Long lake were shorter 

 than those from Pine Tree lake and there were at times three long 

 spines at the angles of the cells, two inferior and one superior spine. 



22. Staurastrum brachiatum Ralfs. PI. 72, Figs. 1-4. 



Brit. Desm. 131, pi. 23, figs. 9A-9G. 1848; Eichler, Pamietnik Fizyograficzny 

 12: 164, pi. 10, fig. 37. 1893; W. & G. S. West, Jour. Eoy. Micr. Soc. 1896: 159, 

 pi. 4, figs. 53-56. 1896; G. S. West, Jour. Linn. Soc. Bot. 34: 391, pi. 11, figs. 

 5-15. 1899. 



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

 deeply constricted, sinus widely open, with apex rounded to acute, 

 isthmus relatively broad ; semicells obversely triangular, with the ven- 

 tral margins straight to slightly convex and the dorsal margins some- 

 what concave; angles continued in short hollow processes, the line of 

 demarcation between cell body and processes very indistinct, processes 

 terminating in three (rarely two) blunt teeth with rounded ends. 



