CLASSIFICATION 455 



they directly poisonous, but lack the aroma of many of the truftles, 

 which are by common consent voted nasty, to say the least, on 

 first acquaintance, but which, due to perseverance and a feeling 

 that it is the proper thing to do, are eventually said to be delicious. 



Key to the Genera 



A. Wall {epispore) of spores rough. 



Peridium having the surface cottony ; sterile base well developed. 



Odaviania. 

 Peridium smooth or only silky ; sterile base present. 



Hymenogaster. 

 Sterile base of peridium absent. Hydnangium. 



B. Wall of spores smooth. 



Peridium furnished with numerous branched fibres springing 

 from various points of its surface and becoming free from it. 



Melanogaster. 



Peridium furnished with numerous branched fibres which remain 

 adnate or attached to its surface. Rhizopogon. 



No fibres springing from the surface of the peridium ; spores 

 minute. Hysterangium. 



NOTES ON THE GENERA 

 OCTAVIANIA 



The general aspect of the various genera included in the Hymeno- 

 gastraceae are, comparatively speaking, much alike externally, and 

 in all cases attention must be paid to microscopic distinctions, 

 more especially the spores, to obtain a clear idea as to genera or 

 species. The peridium being covered with a layer of cottony down 

 or mycelium, at least during the early stage of growth, in addition 

 to the copious weft of white mycelium in the ground from which 

 the peridia originate, along with the well-marked sterile base of 

 the peridium, which can be seen when the peridium is cut in half, 

 are the principal indications of the present genus, which can only 

 be verified by an examination of the spores and the characters pre- 

 sented by the gleba. 



Hymenogaster 



In this genus a section of the peridium should show a well- 

 developed sterile base and the cavities of the gleba quite empty 

 when young, and usually obviously radiating from the sterile base. 

 These characters, supported by the absence of a distinctly cottony 

 coating of the wall of the peridium in the young condition, suggest 

 the genus Hymenogaster. 



Hydnangium 



In this genus the brightly coloured gleba and no sterile base 

 supported by the globose spores, as seen under tlie microscope 

 characterize Hyclnaiwium. 



