584 Long : Local Distribution and Occurrence of 



a more or less rotten condition ; these are further limited by 

 the fact that most of the wood here, such as mesquite (Prosopis), 

 cedar (Sabind) and mountain oak (Querais) do not readily decay ; 

 the fungi are thus confined mainly to elm {Ulmus crassifolid), Cot- 

 tonwood {Popuhis monilifera\ hackberry (Celtis Mississippiensis), 

 etc., which do not form a very prominent part of the timber in this 

 vicinity. Polyporaceae are especially common in this group, over 

 twenty species having been found, Clavaria, Coprimes and Xero- 

 tiis are also represented by several species, one very large club- 

 shaped Clavaria being quite conspicuous on old elm stumps. 

 The beautiful geaster-like Urnitla belongs in this group ; it is 

 strictly a Winter species. 



Group VI contains those growing in the open rocky or 

 gravelly soils, consisting of few species, usually of Lycoperdales 

 and their allies. These are all strongly xerophytic, mainly ter- 

 restrial, the early stages of their existence being passed beneath the 

 soil thus securing better protection. They seem to have adapted 

 themselves better than any of the other fungi to their environments. 



Their spores show a special adaptation to xerophytic conditions, 

 being more or less oily, often hyaline and capable of resisting 

 great heat. Being disseminated by the wind they ought to be 

 widely distributed. These characters have been selected by the 

 necessity of existing in this hot dry climate. 



The most abundant and widely distributed of this group is a 

 species of Polysaccum, which is found in open rocky, gravelly 

 soil or in the mesquite flats. Two rare and unique species 

 closely related to Gyrophragmium come in this group ; the larger 

 is an annulate species 10-14 cm - tall, with short thick stipe, 

 an agaric-like pileus and lamellae, spores slate-black, ovate- 

 spheroid and wind-disseminated ; the other species is much 

 smaller, being only 4-7 cm. tall, with pileus 3 cm. broad, lamellae 

 naked, attached at one end to a central disc and forming a 

 plant somewhat like Montagnites, only the lamellae are persistent 

 and dry and the spores wind-disseminated. Both species are evi- 

 dently connecting links between the Agaricales and Lycoperdales, 

 Myccnastrum has two species here, one * with a leathery peridium, 



* * Found also under elm tree in leaf debris ; young stages of the species were 

 found in August at same place. 



