THE GASTEROMYCETES OP AUSTRALASIA. XIII. THE GENUS PISOLITHUS. By G. H. Cunningham, Mycologist, Plant Research Station, Palmerston North, N.Z. (Plate xvii.) [Read 26th August. 1931.] As has been shown in the previous paper, the family Scleroderrnaceae is limited to the genera Scleroderma and Pisolithus. The latter differs from the former in that the tramal plates, instead of breaking up and disappearing in mature plants, remain to form a honeycomb-like tissue. This is due to the persistence of the tramal plates, the hyphae of which are infiltrated and gelatinized to form a firm, carbonous, brittle tissue. The spore mass at maturity completely fills these cavities; and in developing plants is enclosed within a delicate hyphal layer, free from the carbonous tramal plates. Because of this, these spore masses have been termed peridiola, a term which has persisted since the days of Fries; but as they are not comparable with the peridiola of the Nidulariales, the term is a misnomer and should be discarded. In typical plants the peridium is supported upon a firm rooting base, and as this structure is also carbonous in mature plants, it frequently persists for long after the more fragile peridium has been dispersed. The genus is at home in warm sandy regions, and, although common in Australia, is confined to the thermal regions of the North Island of New Zealand. Pisolithus Albertini and Schweinitz. Consp. fung. Lusatiae sup. Nisk. cresent., 1805, p. 82. — Scleroderma Pers., Syn. Meth. Fung., 1801, p. 151, pro parte. — Polysaccum DC. et Desp., Rapp. voy. tot. rOuest Fr., i, 1807, p. 8. — Pisocarpium Link, Mag. Ges. nat. Freunde Berlin, iii, 1809, p. 33. Plant consisting of a peridium supported on a stem-like rooting base. Peridium of a single thin membranous layer, flaking away irregularly from the apex. Gleba divided into polygonal cells by the persistent tramal plates; cells filled with the spore mass, a true capillitium wanting. Spores coloured, globose, verrucose. Habitat. — Growing half buried in the ground in sandy soils. Type species, Scleroderma tinctorium (Mich.) Pers. Distribution. — Europe; North America; East Indies; Africa; Australia; New Zealand. The genus contains but two, or possibly three, valid species. Of these, P. tinctorius has a distribution similar to that of the genus; P. microcarpus is confined to Australia; and P. Boudieri (Polysaccum Boudieri Lloyd, Myc. Notes, 1904, p. 184) is confined to the Island of Corsica. Dehiscence proceeds from the apex downwards (as does maturation of the gleba) so that old specimens are
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