CLASSIFICATION 457 



O. sieplioisii. — Peridium usually irregularly oblong, base wrinkled 

 or puckered and pitted, with white, branching strands of mycelium, 

 externally rufous ; inside white, liberating when cut a white, milky 

 juice which turns red when exposed to the air, about | in. across ; 

 cells of the gleba minute ; spores globose, echinulate, pale brown, 

 11-14 ji diam. 



A remarkable species, reachly distinguished by its oblong, smooth 

 peridium and the puckered base ending in white, root-like my- 

 cehum. The red colour assumed by the w^hite, milky fluid is not 

 permanent. Smell slight. 



Underground among humus, dead leaves, etc. 



0. compacta. — Peridium globose or of irregular form, whitish, 

 minutely downy ; cells of the gleba globose or irregularly oblong, 

 minute, soon filled with spores ; tramal walls indistinct, |-^ in. 

 across ; spores globose, minutely warted, pale yellow at first, then 

 brighter, 5-6 /j. diam. 



Peridium with a dense rooting mass of snow-white mycelium. 

 Usually gregarious. 



Underground or half buried. 



Melanogaster 



Peridium not furnished with a proper basal point of attachment, 

 hence no sterile basal portion is present ; branched fibres spring 

 from every point of the surface ; cells of the gleba more or less 

 circular in outline, peripheral ones small and becoming larger as 

 the centre is approached, septa thick, continuous with or springing 

 from the inside of the wall of the peridium ; spores smooth, coloured. 



The present genus is characterized by the absence of a sterile 

 basal portion, branched fibres traversing the whole surface of the 

 peridium, and the smooth spores. 



M. varicgatiis. — Peridium irregularly globose, at first ochraceous 

 or clear yellow, changing to reddish rust-colour, covered with ad- 

 pressed down ; tramal plates whitish, then bright orange, pulp in 

 the cavities, black, |-ii in. diam. (spores lirown, smooth, elliptic- 

 oblong, 10x5 u). 



Underground under trees. 



var. byoo»ici(iniis (hg. 4, PI. B). — Peridium subglobose or 

 irregular in form, ochraceous, then rusty red, minutely dowuiy ; 

 walls or tramal plates bounding the cavities of the gleba, whitish 

 or tinged yellow, pulp in the cavities black (spores clear brown, 

 elliptic-oblong, smooth, 9-10x4-5 /t). 



Differs from the typical form in not having the tramal plates 

 bright yellow or orange. This variety is sold in the market at Bath 

 under the name of Red Truffle, and is eaten there in preference to 

 the common truffle, Tuber cestivmn. It grows in clusters of five or 

 six, and sex'cral such clusters arc usualh' found under the same 



