conica_ (Fries) Kummer by the gills soon turning reddish, the reddish cap and the narrow spores. (viii) Subterranean fungi _General notes_ The adaptive habit of growing completely submerged beneath the surface of the ground has developed in all the major groups of fungi. Thus the simplest form related to the common bread-mould have taken up the character just as certain relatives of the disc-fungi (discomycetes) and of the flask-fungi (pyrenomycetes). In the higher fungi in several foreign countries even agarics, polypores and stinkhorns have become hypogeous, but in this country we have a very depauparate flora composed of some twenty-eight species of false (Basidiomycete) truffle. The following key may assist in identifying the different groups of hypogeous fungi for some of these species are of commercial value and includes the French or Perigord truffle, _Tuber melanospermum_ Vittadini which is used as a constituent of Pâté de Foie Gras, and many of the fungi used as poor quality substitutes. There is a long folk-history surrounding truffles and they have been utilised in the production of aphrodisiacs for centuries. Seeking them out was a difficulty and has been overcome in different countries in different ways. Thus in continental Europe, pigs have been used to sniff them out but on finding them the pigs cannot eat the truffles because of a ring placed through their nose. In Dorset a particular breed of dog was developed to do the same job--the Dorset hounds. A simple key would read as follows:-- 1. Spores produced on basidia 2 Spores produced in asci 4 2. Chambers throughout the inner tissue containing spores of approximately the same age 3 Chambers in the inner tissues containing spores found at different stages of development _Hymenogaster_ 3. Basidiospores brown or greenish brown under the microscope, and black in mass _Melanogaster_ Basidiospores colourless or pale honey colour under the microscope and ochraceous in mass _Rhizopogon_ 4. Asci globose, irregularly arranged within the fruit-body and quickly breaking down to shed the spores _Elaphomyces_ Asci globose or club-shaped and arranged in fertile areas which do not rapidly break down to shed the spores _Tuber_ & relatives Basidiomycetes ~Rhizopogon roseolus~ (Corda) Fries Red truffle _Description_: Fruit-body: globular to tubiform and up to 60 mm broad, partly covered in mycelial cords, dirty white, later reddish-tawny gradually reddish and finally olive-brown, it soon becomes tawny on bruising when fresh and young. Spores: medium sized, narrowly ellipsoid, smooth at first, hyaline then pale olive under the microscope and measuring 8-11 × 4 µm.