28 BRITISH FUNGI 



Hydnace^ 



In tliis family the hymenium is spread over sharp-pointed or 

 awl-shaped spines, \\'hich are closel}' packed side by side, on the 

 under-side of the cap in the highest types, where, in some species, 

 tiie spines are an inch in length. Hydiiitni rcpajidiim, a yellowish 

 buff fungus, commonly picked up by the beginner for an agaric, 

 clearly illustrates the structure typical of the family, having the 

 under surface of the cap thickly studded with spines about a 

 quarter inch in length, instead of gills as in an agaric. 



The student will perhaps have begun to grasp the idea tliat in 

 each family there is a gradual sequence of forms, from the most 

 highly specialised representative to the most primitive one. Pro- 

 perly speaking, it should be said from the most primitive types to 

 the liigliest ones, but as the complete forms most clearly illustrate 

 the points most essential to a clear understanding of the classi- 

 fication adopted, I have preferred to commence with such. The 

 student can readih-' re\'erse the order of things, when able to grasp 

 the evolution of fungi generally. 



As the grade of development decreases, we meet with repre- 

 sentatives of the family with the cap growing out laterally, and 

 without a stem, and a step lower are numerous forms which are 

 merely thin, flat expansions growing on wood, having the entire 

 upper surface covered with crowded, very short spines, which in 

 some species are reduced to the most minute warts, visible under 

 a pocket lens. Yet, wherever the surface of a patch of fungus shows 

 a granulated surface, it suggests the family Hydnaceae. 



Thelephorace^ 



This is a family of primitive forms, taking into consideration 

 the gradual evolution of the hymenium or spore-bearing surface, 

 as previously explained. In fact, the one feature stamping the 

 present family is the perfectly smooth hymenium, as compared 

 with a hymenium bearing spines, tubes, or gills, as in the preceding 

 families. In some of the highest genera, as Thclcphora, there are 

 indications of ^^•rinkIes or warts on the hymenium, but they are 

 sufhciently vague to allow of lliclephora being considered as more 

 closety allied to the Thelephoraceas than to the next family, Hyd- 

 naceae. In many species of Corticium and allied genera, the entire 

 substance of the fungus is thin, in many instances not much 

 thicker than a coat of paint on the wood or bark on which they 

 are growing. In such instances the hymenium appears warted or 

 wrinlded, but this appearance is in reality due to the uneven 

 nature of the substratum on wliicli the fungus is growing, and not 

 to any irregularity of the hymenium itself. 



Tliere is a great variety of form met with in the various genera, 

 from the perfectly flat, thin films attached to the wood, as in 



