1921] The Thelephoraceae of North Carolina 155 



3. Aleurodiscus candidus var. sphaerosporus n. var. 



Plate 30 



Plant exactly like A. candidus except for smaller average size of 

 the crusts and for the more spherical spores. The chalk-like, min- 

 utely pulverulent surface and hard, friable, pale flesh are the same 

 in both. The smaller, more broken up pads seem to be the result 

 of the more fragmented and mossy bark of the elm. The spore differ- 

 ence is constant here and taken with the different host furnishes about 

 the right grounds for establishing a variety. 



Spores (of No. 3902) nearly spherical, white, very faintly rough, 

 13-20 X 15.5-24^, most about 16.3 X 19.2pL. Basidia large, about 

 13[x thick. The spores are even more faintly rough than in A. can- 

 didus. 



To be found on most elm trees in Chapel Hill. 



2021. On elm {Ulmus alata), March 10, 1916. 

 3902. On elm (C7. alaia), December 16, 1919. 

 3907. On elm {U. alala), December 18, 1919. Spores exactly as in No. 3902. 



4. Aleurodiscus macrodens n. sp. 



Plates 15 and 31 



Forming irregular, often somewhat elongated patches about 2 mm, 

 to 2 cm. long with well-defined margins and with much the aspect of 

 A. candidus; surface minutely pulverulent, pure white or when old 

 and weathered pale cream; entire thickness only about 150-190[x, 

 the structure in section much obscured by very small crystals and the 

 densely branched paraphyses. 



Basidia entirely embedded, 12-15[x thick, irregular and bent, with 

 four long, stout sterigmata, which only reach the surface by their 

 tips. Spores (of No. 4734, print) commonly rectangular in outline, 

 the surface set with a few large, irregularly placed, bluntly pointed 

 spines which are up to 4[ji, long; body of spore 11.5-15 x 18.5-27[ji. 



In passing the plant would be taken for A. candidus, but when 

 examined is seen to be much thinner with the closely pressed margin 

 not showing a dark underside.. The spores are remarkable and 

 unlike any others in the genus. 

 4734. On bark of a living tree of Fraxinus, December 14, 1920. Type. 



