Cover; Preface; Map; The localities studied; Illustrations; INTRODUCTION; General references; ECOLOGICAL CONSIDERATIONS; Epigaeic lichens; Epilithic lichens; Epiphytic lichens; A migratory lichen; ARTIFICIAL KEY TO THE LICHEN GENERA OF THE NORTH SLOPE; LICHENS OF THE NORTH SLOPE; Lichinaceae; Porocyphus; Collemataceae; Leptogium; Collema; Leciophysma; Heppiaceae; Heppia; Pyrenopsidaceae; Pyrenopsis; Placynthiaceae; Vestergrenopsis; Massalongia; Polychidium; Placynthium; Pannariaceae; Psoroma; Parmeliella; Pannaria; Coccocarpiaceae; Coccocarpia; Peltigeraceae; Peltigera; Solorina