318 University of California Publications in Botany [Vol. (3 



averaging Sfx ; and the third was 32 by 40//,, with 7 by 8 alveoli, averag- 

 ing Ofx.. Among the smaller spores, the number and size of alveoli do 

 not appear to be directly related to spore size ; but the largest spores, 

 i.e., those occurring singly in an ascus, usually have the greatest num- 

 ber and the smallest alveoli. 



This species differs from T. irradians (which shows the similar 

 irregularity in spore sculpturing) in color, being darker; in the asco- 

 carp, which is larger, much more uneven, and more conspicuously ver- 

 rucose ; in outer cortical cells which, while coarse, are not in rows, and 

 merge more gradually into subcortical tissue ; in spores, which are not 

 so dark brown and are smaller. 



Tuber (Eutuber) argenteum sp. uov. 



Plate 30, fig. 28 



Ascocarp silver- white Avith- occasional smooth areas of darker color, 

 horny ; 3 mm.-2.5 cm. in diam., depressed, irregular, convolute and 

 sometimes minutely wrinkled ; surface smooth or in places divided 

 into minute areas by crossing of wrinkles, more or less covered by 

 slender, short, blunt, septate hairs ; gleba brownish with white branch- 

 ing veins; cortical tissue pseudoparenchymatous or coarsely and 

 loosely hyphal, outer cells often forming hairs; subcortical layer of 

 very loose, irregularly placed hyphae ; thickness of peridium 100- 

 200/x ; venae internae numerous, of loose, irregular structure similar 

 to subcortex and tissue between asci, hyphae 5-7fi thick ; venae ex- 

 ternae fewer, filled with loose, irregularly interwoven, branclied 

 hyphae 5-7/1 thick ; both venae internae and venae externae much en- 

 larged at junction with peripheral layer of ascocarp ; asci with or 

 without short stipe, semi-globose, 64-78 by 76-92/a, 1^-spored (gen- 

 erally 1 to 2) ; spores dark brown, ellipsoid, sometimes one end acute, 

 28^4 by 38-56^, regularly and mostly evenly alveolate, generally 8-9 

 by 9-10 alveoli across diameters, sculpturing 4/t thick. 



"In sand among needles of Pinus attenuata. Ingleside, San Francisco 

 Co., Calif., May 11, 1905." 



No. 284, U. C. Col. Type, N. L. Gardner. 



The generally smooth, somewhat spotted surface of the ascocarp 

 of this species, together with the spore shape and size, seem to place 

 it near Tuher niaculatum Vitt. and T. dryophilum Tul. However, 

 it differs from descriptions of both in having a pseudoparenchymatous 

 cortex, and in color, that of T. maculatiim described as first white, be- 

 coming spotted with yellow, finally entirely golden yellow, and that 

 of T. dryophilum as brownish with reddish violet spots. The alveoli 



