NORTHERN POLYPORES 45 



variation in the form of the sporophore from conchate to ungu- 

 late is sometimes very puzzling. 



2. FOMES FRAXINEUS (Bull.) Cooke 



Pileus corky to woody, dimidiate, applanate, usually imbri- 

 cate, often laterally confluent, thinner in American forms, 4-10 

 X 6-15 X 1-6 cm.; surface velvety to glabrous, zonate at times, 

 concentrically sulcate with age, at first white owing to a covering 

 of fine waxy hairs, becoming bay and finally nearly black with 

 age; margin thin or tumid, sterile, cream-colored, pulverulent 

 with reddish blotches, becoming dark and hygrophanous when 

 bruised; context punky, becoming corky, isabelline, tinged with 

 carneous when fresh, 0.5-5 cm - thick; tubes indistinctly strati- 

 fied, 0.5-1 cm. long each season, isabelline when old, reddish- 

 flesh-colored in the younger layers, mouths subcircular, 4 to a 

 mm., edges obtuse, entire, light-flesh-colored, covered at first 

 with a white waxy coat, quickly changing to a darker color when 

 bruised; spores subglobose, smooth, subhyaline, 6-7 X 5-6 ju. 



Frequent on trunks and stumps of certain deciduous trees in 

 New York, Illinois, Ohio, and Michigan. 



3. FOMES OHIENSIS (Berk.) Murrill 



Pileus woody, ungulate, narrow and sometimes decurrent 

 behind, often laterally connate, 0.5-1.5 X 1-2 X 0.3-1 cm.; 

 surface minutely velvety to glabrous, zonate, light-brown, 

 becoming black at the base, and concentrically sulcate with age; 

 margin obtuse, pallid, often undulate; context corky, pallid, 

 indistinctly zonate, 2-5 mm. thick; tubes distinctly stratified, 

 3-6 mm. long each season, nearly white within, mouths circular, 

 3 to a mm., edges obtuse, chalky- white, becoming cremeous; 

 spores globose, smooth, hyaline, 5^; conidia ovoid, smooth, 

 hyaline, 12-13 X 7-8 ju. 



Frequent throughout on structural timbers and dead branches 

 of deciduous trees. 



4. FOMES SCUTELLATUS (Schw.) Cooke 



Pileus woody, dimidiate or scutellate, concave below, 0.5-0.7 

 X 1-1.5 X 0.3-0.5 cm.; surface rugose, tuberculose, zonate, 

 fuscous-black; margin acute, deflexed, pallid to light-brown; 

 context woody, indistinctly zonate, isabelline, 2-3 mm. thick; 

 tubes indistinctly stratified, 1-1.5 rnm. long each season, isa- 

 belline within, mouths subcircular to rhomboid, 4 to a mm., 

 edges rather thin, obtuse, entire, chalk-white, becoming avel- 

 laneous. 



