EXPLANATIONS AND REFERENCES, 

 PLATE CLXXVIII. 



Figures magnified 250 diameters 



PAGE. 



Fig. 1-3. ISACTIS CAESPITOSA, from specimens, Vermont and New Jersey, 245 



" 4-7. GLOEOTRICHIA NATANS, progressive stages of the growth of the 



sheath of a trichome, . . 246 



" 8-12. Progressive stages of another form, .... 246 



Figs. 13, 14. Trichomes fertile, and fading, in the same thallus, . . 246 



Fig. 15-19. Smaller, young, and older thalli, natural size, . . . 246 



" 20. A form from Colorado, . . 246 



