[Read before the Auckland Institute, July 16, 1952; received by the Editor, July 24, 1952] Abstract The first part deals with the Thelephoraceae as' a whole, especially criteria for their classification; the rest is a detailed taxonomic treatment of the New Zealand spp. of Cyphelloideae. It is held that maciofeatures like shape, size and colour of the hymenophore are of less value in classification of Thelephoraceae than microfeatures such as hyphal systems, arrangement of context, structure of hyrnenial layer, and type of ancillary organ-e.g., gloeocystidia, cystidia, dichophyses, acnnthophyses, astero-physes, setae, pseudo–setae, fascicles and conducting vessels. These features, which are illustrated, were examined in hand sections of herbarium material, stained in aniline blue (0.1% in 50% lactic acid) and counterstained if greater contrast was required with 1% aqueous Safranin 0. All N.Z. spp. and some hundreds examined at Kew have monomitic or dimitic hyphnl systems, but both may occur in one genus. Presence or absence of clamp connections, and hyaline or brown hyphae, are also variable within most but not all genera. Ancillary organs provide some of the most useful features for generic segregation. Hfertthus and Serpula are treated as a sub-family Meruloideae of Thelephoraceae. instead of Polyporaceae as previously, because the hymenium is continuous. There is a key to the sub–families, tribes and genera (20) of Thelephoraceae. The sub-family Cyphelloideae is represented in N.Z. by 2 genera, Solenia Pers. (5 spp.) and Cyphella Fries (10 spp.). There are keys to the species of both genera, and each sp. has a full description with distribution and locality records. New species, with Latin and English descriptions, are S. huia, C. hebe, C. totara, C. pyriforma, C. turbinata, C. tongariro and C. pseudopanax. Excluded species are C. cookei Sacc. & Syd., cupulaeformis Berk. & Rav., C. discoidea Cke., C. filicicola Cke., and C. zealandica Cke. & Phillips. Introduction The traditional Thelephoreae was used by Persoon (1822, p. 109), and later by Fries (1874, p. 629) for a tribe to contain fungi with an even hymenial surface as opposed to plants with gills, pores, or definite spines. Later workers have shown that many diverse groups were so included, and have gradually eliminated certain ascomycetes, heterobasidiomycetes and other unrelated fungi. As defined to-day, the family Thelephoraceae contains species with the hymenial layer carried upon a resupinate or pileate hymenophore, and formed from a vertical palisade of basidia and paraphyses with which may be associated additional ancillary organs discussed below. Basidia are simple, one–celled, and produce spores on two or four apical sterigmata. Though nominally even the hymenial surface is seldom smooth; consequently the position of a few genera and species is still uncertain. In some species the hymenium is definitely papillate, and though the microstructure shows them to be members of the Thelephoraceae, on this one feature certain workers have removed them to the Hydnaceae. In Epithele fascicles of hyphae arise deeply within the context, pierce the hymenial layer, and project some distance, giving the hymenium an irregular tufted appearance. Because of this several authors have placed the genus also under the Hydnaceae. In Cyphella and Solenia the hymenial surface is concave and