EXPLANATIONS AND REFERENCES, 

 PLATE CXCIII. 



Figures magnified 250 diameters. 



PAGE. 

 Figs. 1, 2. SIBOSIPHON LIGNICOLA, two well developed forms, . . 273 



" 3, 4. an occasional appearance of a distorted 



growth, .... 273 



Fig. 5-11. conditions of young developments, 273 



Figs. 12, 13 SIROSIPHON ARGILLACEUS, two simple forms from a cluster, . 273 



