Kauffman : The genus Cortinarius 305 



are loosened from the tramal tissue beneath ; not hygrophanous. 

 Stem stout and fleshy, the base enlarged and tapenng upward, L e,, 

 clav^ate. No universal veil. 



Dermocybe. Pileus somewhat innately silky like the preceding, 

 but soon glabrous, dry and not hygrophanous. Flesh thin. Stem 

 slender, rather rigid on exterior, equal or attenuated, stuffed or 

 hollow. No universal veil. Partial veil fibrillose. Plants usually 

 bright-colored. 



Structure of pileus and stem 



There is nothing peculiar in the trama of the pileus of this genus, 

 by which it may be distinguished from related genera. When 

 young, the general description given by de Bary* for Myceiia, etc., 

 applies to everything but the veils. The hyph^ of the basal part 

 of the young *' button" are composed of rather large, oblong cells 

 with air spaces between, these cells becoming smaller and more 

 compact as they approach the apex of the "button,'' and finally 

 end in the beginnings of the young hymenium as a dense, close- 

 lying mass of deeply staining, minute hyphae. At least, this is true 

 of C. sqiiamulosiis Pk. and such others as have been examined. In 

 the mature plant, the trama is largely made up of hyphse, loosely 

 mterwoven, and containing cells, similar to those found in the basal 

 part of the young plant : these hyphse usually become narrower 

 and longer in the gills, gradually changing to the still narrower 

 subhymenial cells in the manner of many other agarics. 



There is one point of interest and importance, however, which 

 has some bearing on taxonomy. This is the cuticle or surface 

 layer of the pileus. In the subgenus Phlegmaciwn^ the cells of 



this layer are long and narrow, lying horizontally parallel or inter- 

 woven on the top of the trama ; their walls are easily transformed, 

 when sufficient moisture is present, into a gelatinous substance. 

 When a vertical section is made through the surface of the pileus, 

 and this is mounted in water, this layer w^idens considerably, or it 

 may be pulled out by the razor so as to assume a more or less 

 vertical position. Beneath this layer may be seen a transition 

 group of cells which connect with the ordinary tramal tissue below. 

 In the subgenera with a dry pileus and no universal veil, the 

 ^pper layer is composed of narrow, more or less long innate hyphse, 

 which compose the silky fibrils there met with. 



* 



Fungi, Mycetozoa, and Bacteria 55. 1S87. 



