1925] 



BURT — THE THELEPHORACEAE OF NORTH AMERICA. XIV 225 



Fructifications broadly effused, thin, waxy-membranaceous, 

 loosely attached to the substratum by a cottony subiculum, 

 tender, small pieces separable, becoming pale ivory-yellow in the 

 herbarium, even, not much cracked, the margin thinning out, 

 fibrillose, with some mycelial strands; in section 200-300 [i thick, 

 not colored, with the thin, compact hymenium supported by a 

 very broad layer of loosely interwoven, thin- walled, granule- 

 incrusted hyphae 1H~2 (x, rarely 3 [x, in diameter, with the 

 hyphae more densely arranged in a middle zone of this layer; no 

 gloeocystidia ; cystidia not incrusted or with only a few incrusting 

 granules, 43/2~6 tx in diameter, protruding up to about 30-50 [x 

 beyond the basidia, often capitate and 6-9 [i in diameter at the 

 apex; basidia up to 6 (x in diameter, with 4 sterigmata; spores 

 hyaline, even, spherical, 43^-6 [l in diameter, copious. 



Fructifications 2-6 cm. long, l-2i/^ cm. wide. 



In woods on bark with the wood underneath wholly decayed. 

 British Columbia. December. 



P. laxa is probably white when growing and assumed the pale 

 ivory-yellow tint in the herbarium; the aspect is like that of P. 

 arachnoidea but with globose spores. P. sphaerospora of Europe 

 has similar spores but much coarser, erect hyphae and different 

 cystidia. 



Specimens examined : 

 British Columbia: Sidney, J. Macoun, 8, type (in Mo. Bot. Card. 



Herb., 5767). 



9. P. humifaciens Burt, n. sp. 



Type: in Burt Herb. 



Fructifications effused, circular, thin, membranaceous, loosely 

 attached by white rhizomorphic strands from the substratum, 

 easily separable, white, becoming somewhat pale pinkish buff in 

 the herbarium, the margin thinning out, floccose; in section 

 150 (X thick, not colored, with hyphae hyaline, up to 5 [x in diameter 

 and coarsest next to the substratum, very loosely arranged, 

 branching and becoming 3 (x in diameter towards the hymenial 

 layer, nodose-septate, with few incrusting granules; no gloeo- 

 cystidia, hymenial layer 30-40 \i thick, continuous; cystidia not 

 incrusted, 3-33^ ix in diameter at base, protruding 25-40 [x, 



