EXPLANATIONS AND REFERENCES. 

 PLATE CXCI. 



Figures magnified 250 diameters. 



PAGE, 

 Figs. 1, 2. SIROSIPHON PULVINATTJS, forma Alpinus, two ends of filaments 



with young spine-like growths, . 269 

 Fig. 3. A broken-oft' section of a filament, the cells bearing the uiiero- 



gonidia enlarging and sliding out of the sheath, . 269 

 Figs. 4, 5. The same increasing in size, .... 



u 6,7. Developing encysted cells, Gloeocapsa; tegument breaks; cells 



are scattered, . . . . . .269 



Fig. 8-10. Cells pass through another cycle of development, . . 269 



" 11-14. Young plants developing from the cells (8-10), . . 269 



Figs. 15, 16. Another form of microgonidia, .... 270 



" 17, 18. Advanced stages of development, .... 270 



" 19, 20. Gradually attain to the condition of Gloeocapsa, . . 270 



Fig. 21. SIROSIPHON CORALLOIDES, a single, rather large stem from a 



tomentose mat, growing on stones of shore of Green 

 Pond, New Jersey, , . , , .270 



