296 



BOTANY. 



examples, while of the latter Usnea, ParmeKa (Fig. 202), 

 and Sticta (Fig. 201) may be taken as illustrations. 



Fig. 9X&.—Parmelia aipolia. A, a portion of a thallus with two apothecia a», 

 and several spermasonia. «, a. B, transverse section of tiiallus tlirough an apothe- 

 cium ; cc, cortical layer of pseudo-parenchyma ; j7, g', sonidial Inyery ; cm, medul- 

 lary layer j h,h, liypothecium ; ^, /, ^. ^thc hymeriiimi ; jfA, asci (thecae) witli 

 ascospores. (7, section through three spermai;onia, s. .', s ; rh, rh. rhizoids. D, 

 ctcrigmata from the interior of a spermagouium, bearing speriuaLia s' 8', AftQt' 



