EXPLANATIONS AND REFERENCES, 

 PLATE CLIX. 



Figures magnified 500 diameters. 



PAGE. 



Fig. 1. CHARACIUM SESSILE five cells, . ... 177 



" 2. CHARACIUM ACUTUM. shortly stipitate, . . .177 



u 3. CHARACIUM PRINGSHEIMII, larger and longer stipitate, . 177 



" 4. CHARACIUM NAEGELII, ..... 178 



" 5. CHARACIUM AMBIGUUM, . . . . . .177 



" 6. CHARACIUM HETEROMORPHUM, .... 178 



" 7-10. POLYEDRIUM TRIGONUM, Var. tetragonum, . . . 184 



" 11-14. POLYEDRIUM GIGAS, type-form, .... 184 



' 15-18. POLYEDRIUM TRIGONUM, Var. bifurcatum, . . . 184 



" 19-23. POLYEDRIUM ENORME, ..... 184 



u 24. POLYEDRIUM MUTICUM, ..... 185 



" 25-27. POLYEDRIUM TRIGONUM, Var. minus, . . .184 



' 28-34. POLYEDRIUM MINIMUM, some in vegetative condition, others 



discharging gonidia, . . 185 



" 35-38. POLYEDRIUM LONGISPINUM, ..... 185 



