130 THE CHICAGO ACADEMY OF SCIENCES 



1. Pileus white or pallid /. lacteus. 



1. Pileus tobacco-color /. tabacinus. 



2. Plant white /. ambiguus. 



2. Plant olivaceous then -cervine I . fuscescens . 



2. Plant whitish, centrally yellowish or pale 



ferruginous /. nodulosus. 



Irpex lacteus Fr. (Plate XIX, Fig. 2.) 



Pileus effused-reflexed, coriaceous, villous, concentrically 

 sulcate, white. 



Teeth close, seriately arranged, acute, more or less incised, 

 white. 



Pileus about 2.5 cm. in width and projecting 10 or 12 mm. 



On dead sticks and branches of all kinds. Our most common 

 species. Often confluent for a distance of several meters, and 

 wholly encircling the branch upon which it grows. In old, 

 weathered specimens the teeth become cervine or ochraceous, 

 when it is /. sinuosus Fr. Sometimes wholly resupinate, oc- 

 casionally with small, irregular, nodulose elevations appearing 

 like abortive pilei. These are not always at the circumference, 

 but may appear at any point on the surface of the fungus. 



Irpex tabacinus B. & C. 



Narrowly reflexed, subzonate, pubescent, long-decurrent be- 

 hind, bright tobacco-color. 



Hymenium concolorous; teeth compressed, obtuse, unequal, 

 seriate. 



On decaying trunks of Populus, woods, Glen Ellyn. 

 Irpex ambiguus Pk. 



Resupinate, adnate, subiculum very thin, floccose-pruinate, 

 white, becoming pallid with age. 



Aculei oblique, somewhat united at the base, minute, very 

 variable, subulate and entire or compressed, acute, truncate, 

 branched, incised or subserrate, white when young, becoming 

 pallid with age. 



Near Chicago. Harper. 

 Irpex fuscescens Schw. 



Coriaceous-membranaceous, olivaceous then cervine, at first 

 orbicular, then confluent and extensively effused, with a narrow 

 fimbriate border. 



Teeth irregular, unequal, compressed, setulose, cervine. 



On dead fallen branches, Winfield and Glen Ellyn. When old, 

 the plant becomes cinnamon-colored or ferruginous. 



Old, weathered specimens become cinnamon-brownish, and 

 these are said to be /. cinnamomeus Fr. (Morgan.) 



Irpex nodulosus Pk. 



Resupinate, forming suborbicular patches 10 to 25 cm. or 

 more in diameter, subseparable ; subiculum thick, tough. 



