14 



NATURAL HISTORY BULLETIN. 



Rather common on rotten wood, especiall}' Salix; easily rec- 

 ognized by its byssine border and abundant soft (when fresh) 

 small roundish thin-walled pores. These tend to become by 

 virtue of position, oblique at length, their size and depth vari- 

 able. 



Thickness i-6 mm: width i~6 cm; length 10-50 cm or 

 more. N. A. F. 1706. 



IX. POLYSTICTUS. 



Pileus coriaceous, membranaceous, or fibrillose; pores 

 evolved successive!}' from the center toward the margin, at 

 first superficial, punctiform, discrete, open, then more deeply 

 excavated, crowded. alwa3-s vertically opposed to the substance 

 of the pileus. Trama formed from the hymenophore. 



This genus is generally easily distinguished from the two 

 next following bv the peculiar manner in w^iich the tubules 

 take rise; with Tra metes (VII) it is closely related but is dis- 

 tinguished by the fact that in the latter the pores are unequal 

 in depth, and follow the direction of the structure of the hymen- 

 ophore. With all this the distinction is not alwa3'S clear,, 

 and species seem to be by authors rather arbitraril}- assigned. 



1. PoLYSTicTus ARCTicus Fries. 



Pileus coriaceous, thin, effuso-reflexed. villous, obsoletely 

 zonate. white; pores obtuse, entire, fuscous the edge pubes- 

 cent. 



Reported bv Saccardo from arctic America and Asia, but 

 certainlv here although not common. Moreover the descrip- 

 tion applies to vounger specimens only. With age the pores 

 become lengthened, lacerate, so that the whole hymenium 

 except the m.argin takes on the appearance of an Irfex. The 

 margin remains always polystictine and pubescent. On dead 

 standing trunk of ^lercns. 



2. PoLYSTiCTUS HiRSUTUS Fn'es. 



Pileus suberose-coriaceous, convexo-plane, rough with rigid 



