316 University of California Publications in Botany [Vol. 6 



it differs from the former in its smaller, thicker-celled pseudoparen- 

 ehj^matoiis cortex, witli the cells not in radial rows, more compact 

 subcortical tissue, more compact venae internae sometimes becoming 

 pseudoparenchymatous, asci never long-stipitate and alveoli generally 

 smaller ; Avhile it is distinguished from T. Gardnerii by its exceedingly 

 minutely verrucose surface, more compact subcortical layer and venae 

 internae, asci 1-3-spored, spores shorter in comparison to width, and 

 sculpturing less variable. The structure of the venae internae is par- 

 ticularly characteristic. It was difficult to secure complete sections of 

 the material, for the hymenium fell away under the knife ; but the 

 dense tissue of the venae internae remained, in most cases, for long 

 distances, forming the skeleton of the original gleba. In no other case 

 was this marked difference in delicacy between the various tissues 

 observed. 



Tuber (Eutuber) irradians sp. nov. 



Plate 29, figs. 16, 17 



Ascocarp brown, 1 cm. in diam., depressed globose, somewhat lobed ; 

 surface minutely verrucose with occasional areas more coarsely ver- 

 rucose ; gleba at first white, becoming brown ; veins few, little branched, 

 white ; cortical tissue pseudoparenchymatous, cells thin-walled, large 

 (to 24/x), in more or less clearly distinct radial rows to depth of 140- 

 160/x, changing abruptly to loose hyphal structure of subcortex ; thick- 

 ness of peridium 380fi ; venae internae and tissue between asci of some- 

 what loosely arranged unconnected hyphae, 5/^ and fewer thick ; venae 

 externae filled with loosely inter^v'Oven hyphae d/jl thick ; asci some- 

 times long-stipitate, easily separable from hyphae, pyriform, elongated 

 or subglobose, 44—64 by 76-92/a, 1-3-spored (generally 1 or 2) ; spores 

 brown, ellipsoid, 36-48 by 40-56ja, alveolate, number of alveoli vari- 

 able, 3 by 3 to 8 by 9 (usually 7 by 8) across diameters; sculpturing 

 4-6/1, thick. 



"Hvpogaeous under Quercus agrifolia, Dimond Canyon, Alameda Co., 

 Cal., Mar. 25, 1905." No. 281, U. C. Col. Type. N. L. Gardner. 



The regular arrangement in radial rows of the pseudoparenchyma- 

 tous cortical cells, in this species, together with the marked variability 

 in number and size of alveoli upon the spore, distinguish it from re- 

 lated forms as they have been described. The possession of a pseudo- 

 parenchymatous cortex and of a verrucose surface separate it from 

 descriptions of T. maculatum and T. dryophilum. It is probably most 

 closely related to T. Gardnerii but differs in several points which are 

 HU'iitioncd under that species. 



