Plate 19 



A. RHIZOCARPON CONCENTRIC!' M (DAV.) VA1NIO 



Plant on rock, showing the orbicular crustose thallus and the concentrically arranged 



apothecia. Enlarged 2^4 diameters. 



B. RHIZOCARPON GEOGRAPHICUM (l.) LAM. & DC. 



Plant on rock, showing the areolate crustose thallus and the immersed apothecia. Enlarged 



3 diameters. 



