Verrucaria margacea , Wahl., an Aqitatic Lichen. 249 
Fig. 9. Algae from culture in 0*15% Knop solution, showing colonial arrangement of algal 
cells, x 500. 
Fig. io. Algae from culture in o*i % Knop solution in form of short filaments, x 400. 
Fig. 11. Ditto, x 800. 
Fig. 12. Vertical section of thallus with perithecia. a, ordinary thallus ; b, stratum of cells 
impregnated with brown deposit ; perithecia. x 80. 
Fig. 13. Inner lining of perithecium, a , with periphyses, s. x 1,000. 
Fig. 15. Aseptate spores, x 500. 
PLATE XIV. 
Fig. 14. Young perithecium in vertical section. /, ordinary thallus; o, ostiole ; /, periphyses; 
a , asci’; s, spores, x 800. 
Fig. 16. Simple spores after treatment with osmic acid. 0. oil granules, x 500. 
Fig. 17. Germinating spores, s. simple; a, 1 -septate; b, 3-septate. x 500. 
Fig. 18. Hyphal network expelled from ostiole of perithecium. x 400. 
