EXPLANATIONS AND REFERENCES, 

 PLATE LVII. 



Figures magnified 500 diameters. 



PAGE. 



Kigs. 1, '2. STAURASTRUM WOLLK-NUM, . . 44 



" 3, 4. STAURASTKUM CORNUTUM. . . 43 



' 5, 6. STAURASTRUM BACILLARR, . . . . .41 



" 7. 8. STAURASTRUM MINNESOTENSE . 43 



" 9. 10. STAURASTRUM PSKUDOCRENATUM, . . . .42 



" 11-13. STAUKASTRUM MINNEAPOLIENSE, .... 45 



" 14, 15. STAURASTRUM CALYXOIDES, . . . . .46 



" 16, 17. STAURASTRUM ERASUM . .... 43 



Fig. 18-20. COSMARIUM INFLATUM, . . . . . .27 



Figs. 21, 22. STAURASTRUM XIPHIDIOPHORUM, .... 44 



Fig. 23-25. COSMARIUM NORDSTEDTII. . . . . .30 



Figs. 26, 27. COSMARIUM SPHALEROSTICHUM, . . 31 



" 28, 29. COSMARIUM BRAUNII, forma MAJOR, . . . .29 



" 30, 31. COSMARIUM SENDTNERIANUM, .... 29 



Fig. 32. COSMARIUM PERFORATUM. ... .28 



Figs. 33, 34. COSMARIUM LOBATUM, . . . 2s 



" 35, 36. COSMARIUM LOEVE, . . . . . .30 



Fig. 37 COSMARIUM CIRCULAR K, . 28 



