1) Class 2) Class hymenomycetes 
The group of Basidiomycetes possessing an exposed hymenium. 
• (n. pl.) One of the great divisions of fungi, containing those species in which the hymenium is completely exposed.
name often given to an informal grouping of fungi that are members of the phylum Basidiomycota (kingdom Fungi). It includes more than 5,000 species ...
Hy`me·no·my·ce'tes noun plural [ New Latin , from Greek ... a membrane + ..., ..., a mushroom.] (Botany) One of the great divisions of fungi, containing those species in which the hymenium is completely exposed. M. J. Berkley. 
[n] - used in some classifications