Plate 60 



Fig. 1. Tetraedron gracile (Reinsch) Hansgirg, x 1000 (after 



Smith) 



Figs. 2-4. Tetraedron limneticum Borge: 2-3, x 590; 4, x 1000 



Fig. 5. Tetraedron limneticum var. gracile Prescott, x 590 



Figs. 6, 7. Tetraedron lobuhtum ( Naeg. ) Hansgirg, x 1000 ( after 

 Smith) 



Fig. 8. Tetraedron lobulatum var. crassum Prescott, x 1000 



Figs. 9, 10. Tetraedron lunula ( Reinsch ) Wille, x 1000 



Fig. 11. Tetraedron lobulatum var. polyfurcatum G. M. Smith 



X 1000 (after Smith) 



Figs. 12-15. Tetraedron minimum (A. Braun) Hansgirg, x 1000 

 ( 14 and 15, after Smith ) 



Figs. 16, 17. Tetraedron muticum (A. Braun) Hansgirg: 16 x 1000- 

 17, X 590 



Fig. IS. Tetraedron muticum fa. punctulatum ( Reinsch ) De- 



Toni, xlOOO (after Smith) 



Figs. 19, 20. Tetraedron obesum (West & West) Wille: 19, x 600- 

 20, X 650 



Figs. 21-23. Tetraedron pentaedricum West & West, x 1000 (23, 

 after Smith ) 



Figs. 24-26. Tetraedron regular e Kuetzing, x 1000 ( 26, after Smith ) 



Figs. 27, 28. Tetraedron planctonicum G. M. Smith, x 1500 



Fig. 29. Tetraedron pusillum (Wallich) West & West, x 1750 



( redrawn from Turner, ex Brunnthaler ) 



780 



