PLATE CXVI. 



FIGS. PAGE 



l2.Arthrodesmus Bulnlieimii Kacib. 1, X 430; 



2, x 460 . . . 105 



3. A. Bulnlieimii var. subincus W. & Gr. S. West. 



x 520 . . . . 105 



4-13. A. convergens Ehrenb. 4, x 360 (after Ralfs) ; 

 5, x 520; 6, large form,, x 500; 7 and 8, 

 forms in which one semicell is destitute of 

 the spines, x 520; 9, division of preceding 

 form, showing the acquirement of fully deve- 

 loped spines by the new half-cells, x 520 ; 

 10, form produced by rapid division and 

 entirely destitute of spines, x 520; 11, divi- 

 sion of such a form showing fully developed 

 spines re-acquired by the new semicells, x 

 520; 12, x 520; 13, zygospore, x 520 . 106 

 14. A. subulatus Kiitz. x 520 109 



