EXPLANATIONS AND REFERENCES, 



PLATE CLXXXVIII. 



Figures magnified 250 diameters. 



PAGE. 

 Fig. 1-4. SCYTONEMA ciNEREUM, from shaded rocks, New Jersey and 



Pennsylvania, . . . 258 



" 5-9. SCYTONEMA CORTEX, forma corrugata, a few typical forms from 



the bark of trees, . . . 257 



forma brunea, probably the same but in 

 older condition, . . . 258 



" 10-12. SCYTONEMA CINEREUM, from New York State, . . . 258 



Figs. 13, 14. " ' from Florida, . . .259 



" 15, 16. PETALONEMA ALATITM, from specimens from clifts, Niagara 



Falls, New York, . . .267 



