30 Murrill: Polyporaceae of North America 



used Polyporiis in the Karstenian sense instead of Caloporus and 

 proposed the new name Melanopiis for the group to which Karsten 

 had assigned the name Polyporellns (Hymenom. Eur. 137. 1887). 

 One finds, therefore, four modern generic names, Polyporellns, 

 Leiicoporus, Ccriopoms and Melanopiis, associated either with the 

 type or with a near ally of the type of the genus Polyporiis and 

 hence synonymous with it. 



The species of this genus are in general very similar in appear- 

 ance and habit, most of them being small dark-colored plants 

 attached to fallen branches and other decaying wood on or near 

 the ground. One species, however, P. caudiciniis, is very large 

 and does considerable damage to living trees, especially in Europe 

 where it is abundant. The smallest plant of the genus is P. Acic- 

 ula, a tropical form only two millimeters in diameter represented 

 by a single specimen in the Kew herbarium. Many other species 

 of this group are based upon very scanty collections, some well 

 preserved, others now in poor condition, and most of them inade- 

 quately described. The task of the monographer is, therefore, 

 in this case unusually difficult and his results more or less unsatis- 

 factory. 



Synopsis of the North American species] 



1. Stipe pallid or light brown, centrally attached, not darker than the pileus. 2. 

 Stipe wholly or partly black or fuliginous, variously attached, usually darker than 



the pileus. I7- 



2. Margin of pileus not ciliate. 3- 

 Margin of pileus ornamented with cilia, which often disappear with age. I2. 



3. Pileus beset near the margin with hydnoid processes. I. P. hydniceps. 

 Pileus plainly villose, tomentose or scabrous, often becoming glabrous with age. 4. 

 Pileus minutely tomentose or glabrous from the first. 8. 



4. Pileus scabrous, irregular, umbrinous, margin involute ; stipe scabrous, tubes small, 



4 to a mm., dissepiments dentate. 2. P. scabriceps. 



Pileus villose or tomentose. 5- 



5. Pileus becoming virgate from the rupture of the cuticle, tubes 2 to a mm. , decur- 



rent, dissepiments dentate. Z- ^- virgatus. 



Pileus not becoming virgate. "• 



6. Pileus less than 2 cm. in diameter, ochraceous, tubes 2 to a mm., decurrent to the 



base of the stipe. 4- P- delicatus. 



Pileus m.ore than 2 cm. in diameter. 7- 



