PLATE LXVIIL 



FIGS. PAOE 



1-2. Cosmarium globosum Buliili. x 500 . 29 



3-5. C. globosum var. minus Hansg. 3, x 570 (after 

 Nordstedt) ; 4, x 520 ; 5, x 416 (after 

 Belponte) . . . .30 



6-8. C. subarctoum (Lagerh.) Racib. 6, x about 



550 (after Raciborski) ; 7 and 8, x 520 . 31 

 9. C. subarctoum forma punctata. x 520 . 32 



10. C. pericymatium Nordst. x 570 (after Nord- 



stedt) . . . .34 



11. C. pericymatium var. eboracense West & G. S. 



West/ x 520. . . . 34 



12-14. C. pseudarctoum Nordst. 12, x 650 (after 

 Nordstedt) ; 13 and 14, x 520. [Consult PI. 

 LXXII, figs. 40-41.] . . .32 



15. C. pseudarctoum forma. x 520 . . 34 



16. C. Novse-Semlize Wille. , x 660; /> andc, x 



330 (after Wille) . . .35 



17-J8. C. NovsB-Semlise var. sibericum Boldt. 17, x 



400 (after Boldt) ; 18, x 520 . .36 



19-28. C. Regnesi Rein&ch. 19 and 20, x 520; 21-25, 



x 1280; 26-28, zygospores, x 520. Fig. 23, 



normal division of cell ; 24, division in which. 



the new semicells regain the more pronounced 



character of the species after having partially 



lost it by repeated divisions ; 25, chain of 4 



individuals formed by rapid division, the two 



middle cells being as yet imperfectly developed 36 



29-31. C. Regnesi var. montanum Schmidle. 29 and 



30, x 520; 31, x 1280 . . .39 



32-34. C. Reynesi ; intermediate forms between the 



type and var. montanum, x 1280 . . 39 



35-36. C. Regnesi var. tritum West, 35, x 1280; 36, 



x 520 . . . . 38 



37-39. C. cymatonotophorum West, 37, x 740; 38, x 



520; 39, x 1000 . . .40 



