_Coriscium_ is now considered to be an association of an algae and a Basidiomycete, the latter being the agaric, _Omphalina hudsoniana_ (Jennings) Bigelow, which resembles _O. ericetorum_ but for the pinkish coloured stem. _Botrydina_ may be a complex of several separate associations of an algae with different species of _Omphalina_. In the high mountains the association is with _O. luteovitellina_ (Pilát & Nannfeldt) M. Lange a small uniformly bright yellow agaric, whilst in _Sphagnum_ bogs it is with _O. sphagnicola_ (Berkeley) Moser. _Myxomphalia maura_ (Fries) Hora, a fungus typical of burnt ground, is also reported to take up this association in lowland woods and _O. velutina_ (Quélet) Quélet appears to be capable of forming a loose relationship with algal cells also. This is a most interesting association and research work is still at an early stage. In the tropics and subtropical regions of the world, similar associations are found on rotten and decomposing trunks and stumps. In these examples the _Basidiomycetes_ are frequently fairy-clubs, particularly species of _Multiclavula_ (‘many small clubs’). A few species of this genus may be found also in North temperate woodlands. _Botrydina_ also grows in Europe with _Stereum fasciatum_ (Schw.) Fries and _Athelia viride_ (Bres.) Parm. (see p. 176), and _Odontia bicolor_ (Fries) Quélet is rarely collected without green algal cells buried in the thallus. Perhaps associations like this are much commoner than at first supposed. Probably the most remarkable of this group of poorly known organisms is _Cora pavonia_ (Sw.) Fries which produces masses of interlocking fans; it is tropical and found in Brazil. Mountain fungi: general remarks There are several groups of mountain fungi, some mycorrhizal formers, some which prefer peaty soil and some which are associated with algae forming a loose relationship--the Basidiolichens. When the mountain top is covered with such dwarf willows as _Salix herbacea_ or _S. reticulata_ the leaves are cast each year, woody tissue develops above and below the ground; in fact all the processes taking place in our familiar woodlands are also taking place in these communities, the only difference being that the trees are dwarf. Indeed it looks quite odd to see normal sized agarics growing amongst the woody stalks of dwarf trees, the leaves of which are often one-tenth the size of the fruit-bodies, but this is what happens.