PLATE CXXVII. 



FIGS. PAGE 



1-5. Staurastrum striolatum (Nag.) Arch. 



I, x 570 (after Nordstedt) ; 2, x 

 500 ; 3-5, zygospores, x 500. Fig. 

 4 is the side view of the zygospore, 

 and fig. 5 shows a zygospore in an 

 oblique position . . .177 



6. St. striolatum var. divergens W. & G. S. 



West, x 520 . . . 178 



7. St. ditspar Breb. forma. x 520 . 187 



8-ll.St.punctulatum&Teb. 8-10, x 520; 



II, x 500 . . .179 

 12. St. punctulatuin forma minor. x 460 . 181 

 13. Zygospore of St. punctulatuin var. Kjell- 



mani Wille. x 520 . . 182 



14. Zygospore of St. punctulatuin. x 500 181 

 15. St. 'punctulatuin var. subproductum W. 



& G. S. West, x 520 . . 182 



16. St. alternans var. pulchrum Wille. x 

 400 (after Wille). In fig. 16 a the 

 lower semicell is outlined in dots to 

 give a general idea of the form of the 

 sinus . . . .172 



17-19, 21, 22. St. punctulatuin var. Kjellmani Wille. 



17, x 400 (after Wille) ; 18, x 330 

 (after Wille); 19, x 520; 21, x 

 520; 22, x 400 . . . 182 



23. St. inflatum W. & G. S. West. x 520 191 

 24. St. turguscens De Not. var. arcticum 



Wille. x 400 (after Wille) . 169 



