and includes a survey of additional data on European and extra-European material previously related to the genus. Of the additional species studied by me, only one, T. coccosporum Lett., belongs to Thelocarpon; the remainder are either synonyms of species already described or belong to other genera. With this single addition the number of species in the genus is now thirteen. So far Thelocarpon has been recorded mainly from Europe and the U.S.A. All the species are very small and inconspicuous and their known distribution probably reflects areas of intensive collecting. There are no correct records from Canada, the tropics or the southern hemisphere. The genus is poorly represented in most herbaria and I am particularly grateful to directors and staff of the following institutions for loans of material in their care : Botanischer Garten und Museum, Berlin-Darlem (BD); British Museum (Natural History), London (BM); Herbarium Bogoriense,
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