G. MASSEE ON BASIDIOMYCETES. 7 



the same level ; hence the hymenium, as seen with the naked eye, 

 appears as if pierced with myriads of pinholes in the majority of 

 species. In some forms the holes or openings of the component 

 tubes are so minute that they cannot be seen witli the unaided 

 eye ; whereas in the genus Hexagona the openings are hexagonal, 

 two to three lines across, and present the appearance of a honey- 

 €omb. In all cases the walls of the cavities are studded with 

 projecting basidia bearing spores. The primitiv^e genera, as in 

 Coi'ticiiun, form thin expansions, often of considerable dimensions ; 

 then follow numerous species growing on wood under the form of 

 semicircular brackets, bearing the hymenium on the under surface, 

 the upper surface being sterile, frequently scaly or hairy, and 

 often bright- coloured. Finally, numerous species have reached 

 the mushroom type of structure, with a central stem, and having 

 the hymenium protected from the elements by being placed on 

 the under surface of the cap. In addition to this mode of pro- 

 tection, a supplementary protective arrangement is met with in 

 some of the higher species, consisting of a thin membrane reach- 

 ing from the upper part of the stem to the margin of the cap or 

 pileus ; by means of this arrangement the hymenium is entirely 

 concealed from view until the spores are ready for dispersion, 

 when the membrane separates from the margin of the pileus, 

 collapses, and forms a ring round the stem, or in some species it 

 entirely disappears after having fulGUed its protective function. 

 In the genus Pohjporus, taken in the broad sense, many of the 

 species are woody and perennial, forming a new stratum of pores 

 each season. On the other hand, the species of Boletus are all 

 annuals and very fleshy, the pileus in many species resembling a 

 penny bun in shape and size, and supported on a stout stem five 

 to seven inches long and two inches thick. Several kinds of 

 Boletus are edible, others contain poisonous alkaloids. About 

 two thousand five hundred species are known. The vvoody forms 

 occur in both temperate and tropical regions, whereas the soft, 

 fleshy genera, Boletus and Strobilom;i/ces, are mostly confined to 

 temperate regions, the first-named genus being most abundant in 

 the northern hemisphere, the latter in the southern. 



Agaricine.^:. — In this, the most modern of the families passed 

 iunder review, the hymenium occupies the entire surface of very 

 thin plates or lamellse, popularly known as gills. In the higher 

 forms, as the common mushroom, and the entire category 



