CLASSIFICATION 505 



the dissepiments ; asci Iroadly elliptical or globose ; spores col- 

 oured, smooth or variously ornamented on the wall. 



* Wall of spores reticulated or covered with a network of raised ribs. 

 T. cBstivum. — Ascophore irregularly glotose, tlackish brown, 

 covered with large, hard, pyramidal or 4-sided warts, often in- 

 dented at the base, 1-4 in. diam. ; gleba whitish, then brown, dis- 

 sepiments numerous, much branched and wavy ; spores elliptical 

 or subglobose, netted with a rather large, shallow mesh, 40-60 x 

 30-40 jL, or 30-40 /x diam. 



Distinguished by the coarsely warted ascophore and the large 

 spores ornamented with a large, shallow network. Perhaps the 

 best of our edible truffles, but much inferior to the exotic Perigord 

 truffle, T. mclanosporum. Taste somewhat insipid ; smell some- 

 what resembling that of beer yeast. 



Underground in woods, especially under beeches ; just below 

 the surface, or sometimes above ground under heaps of dead 

 leaves, etc. 



T. bituminatum. — Ascophore globose or ovate, regular, blackish, 

 and co\ered with small many-sided, pyramidal warts, 1-3 in. diam. ; 

 gleba with the dissepiments mostly radiating from the base ; asci 

 subglobose, with long stalks ; spores globose or broadly elliptical, 

 translucent brown, with a large large-meshed, shallow network, 

 40-50 /x, or 45 X 60 /^. Smell strong, like horse-radish. 



Most nearly allied to T. mesentericum, differing in its larger 

 spores and less wavy dissepiments. Differs from T. cestivum in its 

 strong smell and smaller warts on the wall of the ascophore. 



Usually deeply buried in sand. 



T. fcetidHm. — Ascophore irregularly globose, variously lobed or 

 nodulose, smooth or sometimes minutely wrinkled, brownish, J-ii 

 in. diam. ; gleba whitish, then reddish brown, dissepiments whitish, 

 much branched and anastomosing ; spores with a rather small- 

 meshed, shallow network, 27-36x20-30 /x. 



Smell and taste resembling rancid oil, with a suggestion of onions. 



Subterranean under trees. 



T. macrosporum. — Ascophore subglobose, sometimes nodulose, 

 often cracked, densely covered with minute flattened warts, blackish 

 and spotted with rusty brown, |-2 in. across ; gleba at first white, 

 changing to purplish brown or blackish, dissepiments numerous, 

 mixed with finer dusky lines ; asci subglobose ; spores elliptical, 

 brown, with a small-meshed, shallow network, 50-65x35-40 /x. 



Smell strong, like onions. Readily known by the large elliptical 

 spores. 



Underground, usually in clay soil, under oaks, willows, poplars, etc. 



T. excavatum. — Ascophore subglobose or irregularly shaped with 

 a basal indentation, ochraceous, minutely wrinkled, |-i in. diam. ; 

 gleba tinged ochraceous, dissepiments white, radiating from the 



