[Vol. 13 

 320 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



glabrous and densely radiate-rugose, margin lobed and crisped 

 and in some specimens proliferous, young hymenium yellow, 

 becoming when old brick color when moist, paler when dry. In 

 the mature state the 3-5 concentric zones are more distinct and 

 slightly elevated. The specimens roll up in drying and become 

 hard and brittle." 



We have but very few strictly sessile or renifonn species of 

 Stcreum, although sessile specimens of common efifuso-reflexed 

 species were described as distinct species; more collections of S. 

 atrorubrum are needed to clear up this important character in 

 this case. The upper surface of the fragment seen by me is now 

 dusky brown to bone-brown, glabrous, shining, strongly radiately 

 rugose and shallowly concentrically sulcate; hymenium even, 

 glabrous, avellaneous; in structure about 800 [l thick, composed 

 of (1) an intermediate layer of longitudinal, densely arranged, 

 thick-walled, rigid hyphae 3-3}^^ (x in diameter, (2) bordered on 

 the upper side by an opaque, brown layer 60 [l thick which gives 

 the color to the pileus, and (3) curving on the lower side into a 

 hymenial layer 300 [i thick; no cystidia, gloeocystidia, nor con- 

 spicuous conducting organs; spores up to 7 X 2-2^ [i present 

 but may not belong for only 2 seen. 



The date of the collection — May — and appearance of the 

 hjTnenium suggest a specimen of the preceding season which has 

 held over through the winter and may have had somewhat dif- 

 ferent characters when growing. The very dark-colored, strongly 

 radiating rugose upper side of the pileus is noteworthy. 



Specimens examined: 



British Columbia : on old logs, J. Macoun, 86, type, a fragment 

 examined. 



S. radicans (Berk.) Burt, Mo. Bot. Gard. Ann. 7: 108. pi. 3, 

 f. 16. 1920. 



In a collection of this species from Porto Rico, in Mo. Bot. 

 Gard. Herb., 7585, the spores have become slightly colored, 

 showing that this species belongs in Thelephora. The species is 

 really an intermediate between Stereum and Thelephora, having 

 the dense, intermediate layer of Stereum and also vesicular gloeo- 

 cystidia in the hymenial layer. The spores are still hyaline in 3 

 of the 4 gatherings which I have studied. 



