1916] Gilkcy: A Revision of flir Tiihcralcs of California 315 



ill a comparison of the two preceding descriptions, while the principal 

 distinguishing characteristics of the spore of the latter plant, i.e., 

 long-ellipsoid with decidedly pointed ends, is not mentioned in Vitta- 

 dini's description. Except for three views of the ascocarp in Vitta- 

 dini's Monographia Tiihcracearum, I have been unable to find ilhis- 

 trations of T. oligosporuni. It is apparently rare, for Tulasne simply 

 paraphrases the original description, noting at the end "noii vidimus," 

 while Fischer, in Rabenhorst's Knjptogamen-Flora, includes it under 

 the heading "Ungenligend bekannte Arten." 



While the differences in color and surface characters may not be 

 sufficient to. separate our specimen from T. oUgosporum, yet so many 

 points are at present doubtful that it seems best to keep them distinct 

 until more data for both can be secured. 



Tuber (Eutuber) separans sp. nov. 



Plate 29, fig. 19 



Tuher excavatum Hk. non Vitt., Proe. Cal. Acad. Sci., 3d sor.. vol. 1, no. 8 

 (1899), p. 273. 



Ascocarp lead-purple (preserved) 1 to 1.2 cm. in diam., semi- 

 globose, convolute, surface very minutely verrucose ; gleba similar in 

 color to cortex ; veins inconspicuous ; cortex pseudoparenchymatous, 

 cells becoming smaller within and changing to compact subcortical 

 layer of unconnected hyphae ; walls of outer cortical cells somewhat 

 thickened ; thickness of peridium 200-260^ ; tissue between asci of 

 mostly loose, unconnected not parallel hyphae, 4^&jx thick ; venae in- 

 ternae very compact, hyphae parallel, often connected, sometimes be- 

 coming pseudoparenchymatous; venae externae filled with loose, 

 tangled hyphae 4-6/i, thick ; asci short stipitate, semi-globose, 56-68 by 

 60-92/x, 1-3-, rarely 4-spored ; spores brown, globose, ellipsoid, 40-48 

 by 48-56/t, alveolate, 5-10 by 7-11 alveoli across diameters. 



''Beneath oaks in claye^^ soil, Laundrv Farm, Alameda Co.. Calif., 

 April." " " "No. 159, Hk. Col. Type. 



The single specimen found under No. 159, which is listed by Hark- 

 ness as Tuber excavatum, shows no indication whatever of the basal 

 cavity which is described as characteristic of that species. The alveoli 

 of the spore are smaller and more irregular in number and size than 

 they are described for T. excavatum, and the venae internae are not 

 composed of tangled hyphae. Instead of converging at the base as in 

 the latter species, the venae externae open at various points of the 

 surface. The species comes nearest T. irradians and T. Gardnerli but 



