Pileus corky, rigid, dimidiate, sessile, imbricate, applanate, convex below, triangular in section, 6-12 X ~o X 2-4 em.; surface isabelline-avellaneous to cinereous or smoky-black with age, slightly sulcate, zonate at times, tuberculose to colliculose in the older portions; margin usually thin, pallid, glabrous; con- text isabelline, soft-corky, homogeneous, 5-7 mm. thick; tubes labyrinthiform, becoming nearly lamellate with age in some specimens, 1-2 em. long, I-Z mm. broad, chalk-white or dis- colored within, edges obtuse, entire, ochraceous to avellaneous.
Reported by Harkness as occurring on oak in California.