INTRODUCTION TO CRYPTOGAMIC BOTANY. 251 



well as Australia, and there is, at least, a closely allied form in 

 India. Of the larger genera, such as Agaricus and Poly- 

 porus, some species, as for instance the common mushroom 

 and P. lucidus, occur in almost every part of the world ; and 

 in hotter climates the Agarics are mostly identical with 

 species of more temperate climes. Of Folypori certain species, 

 as P. sanguineus and xanthopus, are at home wherever the 

 climate is tropical or sub-tropical ; and the more the species are 

 examined, the more widely do we find that they extend. 

 Polyporus is, however, far more the genus of warmer countries 

 than Agaricus, and accordingly we find species which we should 

 in vain search for in temperate regions, extending in sub-tro- 

 pical districts from Carolina to the Philippines. In the 

 Sikkim and neighbouring Himalayas, which abound in Fungi, 

 we have species of every different climate at different heights. 

 We have below, Pol. sanguineus and xanthopus; higher 

 up, we have the species of Ceylon and Java; we have then the 

 species of southern Europe, and finally the more northern 

 species ; or, if we have not the identical species, we have 

 others so nearly aUied that it is matter of difficulty to distin- 

 guish them. One species occurred as high as eighteen thousand 

 feet, while others flourished in the warm valleys at a compa- 

 ratively low height above the level of the sea. The Hymeno- 

 mycetous fungi were, however, far the most abundant, and the 

 Sphserias were barely represented. 



247. Fungi occur in locahties as various as the forms which 

 they assume ; the sandy desert, the open field, the close wood, 

 the bleak mountain, provided there be sufficient moisture, have 

 all their proper species, and those which are parasitic are 

 almost as numerous as the plants which they affect ; but not 

 ■only do they cover the surface of the earth in countless myriads, 

 but there are numerous species which are distinctly subter- 

 ranean in their habits. The truffles comprise a large number 

 of species, included in numerous genera differing extremely in 

 structure. They occur in various cHmates, but are confined 

 almost entirely to calcareous districts. The species are very 

 generally diffused, the same kind occurring in central America, 

 Italy, and Sweden. They prefer the warmer temperate regions ; 



