xvi CONTENTS 



PAGE 



D. Evolution of Archilichens .... 287 



a. Thallus of Pyrenocarpineae 



b. Thallus of Coniocarpineae 



c. Thallus of Graphidineae 



d. Thallus of Cyclocarpineae 



A A. LECIDEALES 



aa. COENOGONIACEAE 



bb. Lecideaceae and Gyrophoraceae 

 cc. Cladoniaceae 



1. Origin of Cladonia 



2. Evolution of the primary thallus 



3. Evolution of the secondary thallus 



4. Course of podetial development 



5. Variation in Cladonia 



6. Causes of variation 



7. Podetial development and spore-dissemination 



8. Pilophorus, Stereocaulon and Argopsis 

 BB. LECANORALES 



aa. Course of Development 

 bb. Lecanoraceae 

 cc. Parmeliaceae 



dd. USNEACEAE 



ee. Physciaceae 



CHAPTER VIII 



SYSTEMATIC 

 I. CLASSIFICATION 



A. Work of successive Systematists . . . 304 



a. Dillenius and Linnaeus 



b. Acharius 



c. Schaerer 



d. Massalongo and Koerber 



e. Nylander 



/ Miiller-Argau 



g. Reinke 



h. Zahlbruckner 



B. Families AND Genera OF AscoLicHENS . . 311 

 C Hymenolichens 342 



II. NUMBER AND DISTRIBUTION 



I. ESTIMATES OF NUMBER 



2. GEOGRAPHICAL DISTRIBUTION 



A. General Survey 343 



B. Lichens of Polar Regions 345 



C. Lichens of the Temperate Zones . . . 348 



D. Lichens of Tropical Regions .... 352 



III. FOSSIL LICHENS 



