Murrill: Polypokaceae of North America 99 



(Margin sometimes concolorous.) Hymenium pale cinnamon- 

 brown, generally effused at the base and abruptly sub-porous at 

 the margin. Sinuses labyrinthiform, flexuose, intricate, torn and 

 toothed ; very similar to those of D. unicolor Fr., except in color 

 and much larger size. The largest single pilei observed measure 

 about two inches in length by three in breadth." 



Authentic specimens of this plant have not been seen, but 

 there appears to be little in the description to distinguish it from 

 forms of Cerrena unicolor. 



FAVOLUS Beauv. Fl. Owar. I : i. pi. i. 1805. 



This genus was founded upon a single species, F. hirtus Beauv., 

 which, although commonly known under the name of Hexagona 

 hirta, recalls the true honeycomb-like structure of the hymenium 

 which was originally the distinguishing feature of the genus 

 Favolus. The genera Hexagona and Favolus, both monotypic in 

 origin, were interchanged by Fries because the species were un- 

 familiar to him and they have been incorrectly used ever since. 



In the Systema, Fries followed Beauvois and included Hexagona 

 under the subgenus Favolus of Polyporus. In the Epicrisis, Fries 

 includes F. hirtus, Beauvois' type, in the genus Hexagona and fol- 

 lows it with H. Mori, Pollini's type. He then begins his genus 

 Favolus with F. europaeus, a synonym of H. Mori. 



The plants of this genus are not well known, few as they are. 

 The two species ordinarily collected in North America are con- 

 fined to the tropics, a comparatively unworked region. There is 

 little difference either in the abundance or the distribution of these 

 species, but they may be easily distinguished by color and mark- 

 ings. Both species vary rather remarkably in the size of their 

 pores. Berkeley frequently commented upon it in his writings and 

 his varieties testify to the fact. There appears to be absolutely 

 no other different character accompanying this difference in pore 

 measurement. A large collection of specimens is needed in order 

 to guess at the cause of this variation, which at times amounts to 

 two or three diameters. 



Synopsis of the North American species 



Surface marked with white and light-brown zones. I. F. tenuis. 



Surface variegated with dark-brown and purple zones. 2. F. variegata. 



