XII. LICHENES. 



943 



Parmelia parietina. 



Spennatia of ^ to , 5 in. 



(Tulasne.) 



Parmelia parietina. Vertical section of thallus, 

 and of a spermogonium from which the spermatia 

 are escaping (mag.). (Tulasne.) 



Stcreocaulon ramulosut. 



Parmelia parietina. 

 (terminating spores (mag.) 



Vmbilicaria vellea. 



Usnea barbata. 



