326 Vniversiiij of California PuMications in Botany [Vol. g 



canals as formerly fertile canals which have lost their asci. The spores 

 of the species belonging to Piersonia are characteristic, for though 

 alveolate sculpturing is not unusual in the Tuberales, in this case the 

 walls of the alveoli are sometimes as thick (generally one-half as 

 thick) as the diameter of the alveolar cavity, making the epispore 

 appear continuous, with regularly placed, generally hexagonal de- 

 pressions. These are apparently arranged in definite concentric 

 circles, the centers occurring upon two opposite sides of the spore. 



Fischer described the genus Piersonia in the Botanische Zeitung 

 (1908), Heft VIII and IX, pp. 149-154, from No. 126 (since named 

 P. hispora), of the University of California cryptogamic herbarium. 

 His illustrations, pi. VI, figs. 5-10, picture well the characteristics of 

 that species. The conception of the genus as above described will be 

 found to be practically that of Fischer. 



Ascocarp 1-1.5 cm. in diam.; gleba showing orange-colored sj^ots; sterile 

 tissue of gleba forming veins, generally narrower than hymenial areas; 

 asci 1-4- (generally 4-) spored Piersonia alveolata. 



Ascocarp reaching 8 cm. (generally 6) in diam.; gleba without orange- 

 colored sjiots; sterile tissue of gleba generally broader than hymenial 



areas, not forming distinct veins; asci 1-2- (rarely more) spored 



Piersonia hispora. 



Piersonia alveolata Hk- 



Plate 28, figs. 1, 2, 3, 4 



Proc. Cal. Acad. Sci., 3d ser., vol. 1, no. 8 (1899), p. 275. 



Piersonia scahrosa Hk., Proc. Cal. Acad. Sci., 3d ser., vol. 1, no. 8, p. 275. 



Eydnobolites exeavatum Hk., Proc. Cal. Acad. Sci., 3d ser., vol. 1, no. 8, 



p. 266. 

 Pachyphloeus ligericus Hk. non TuL, Proc. Cal. Acad. Sci., 3d ser., vol. 1, 



no. 8, p. 269. 



Ascocarp white, becoming yellow or brown, 1.3 cm. in diam. 

 sliglitly lobed, surface scabrous, sometimes pubescent; gleba yellowish 

 witli orange-colored dots, separated by lighter-colored veins; outer 

 cortical tissue of branched intertangled hyphae, often with more or 

 less regular globose thickenings, sometimes so close and even as to 

 make hyphal thread appear like string of beads; hyphae often pro- 

 jecting from surface, forming hairs; tissue beneath other hyphae be- 

 coming pseudoparenchymatous, of distinctly angled cells reaching 20^ 

 in diameter, cells becoming smaller within, changing to subcortical 

 tissue of compactly arranged, sometimes connected hyphae running 

 parallel to surface of ascocarp ; thickness of peridium, 220-600ju, ; venae 

 externae generally short, lined with paraphyses, filled with loose, 

 branched hyphae similar to outer cortical tissue, inner hyphae less 



