100 



Mycologia 



established the species, or by Ed. Fischer (Tuberaceen und 

 Hemiasceen in Rabenhorst, Kryptogamen-Flora von Deutschland. 

 V Abtheilung, 1897) 5 tfte asc i an d spores are larger (the meas- 

 urements for T. Borchii given by Fischer being 60—80 by 60-100 fi 

 for asci, and 24-35 by 28-49 /* f° r spores). The latter measure- 

 ments made without the sculpturing, may be compared with 28- 

 40 by 36-60 /x, the measurements of the Michigan material made 

 in the same manner. In descriptions of T. Borchii no mention is 

 made of the distinguishing characters of the Michigan specimens, 

 i.e., the absence of or very small venae internae, the exceedingly 

 large venae externae sometimes becoming hollow, and the dis- 

 tinct palisade-like hyphae bordering the latter veins. The spore 

 measurements of T. macro spomm, given by Fischer are com- 

 parable to those of this species (28-45 by 38-80), and the surface 

 of the ascocarp is described as having " kleinen, abgerlacht pyra- 

 midenformigen Warzen oder polygonalen Feldern," but here, 

 also, paraphyses and the peculiar nature of the venae externae 

 are not mentioned, while the reticulation of the spore surface is 

 described — also figured by Tulasne (Fungi Hypogaei, 1851) — as 

 very close, 10 by 15 alveoli occurring across diameters in Tulas- 

 ne's illustration. The figure and descriptions represent the spore, 



Fig. 1. Spores of the two species described. On the left, one of Tuber 

 canaliculatum X 385. On the right, of Tuber unicolor X 625. 



too, as much longer in comparison to its short diameter than that 

 of the Michigan species. 



Tuber unicolor sp. nov. 



Ascocarp yellow-brown, 1-2 cm. in diam., somewhat convolute 

 to sometimes deeply furrowed; surface very minutely scabrous; 

 gleba yellowish with slender white veins ; outer cortical tissue 



