PREAMBLE. 14

the Edible Boletus is the type. Another example, the Hedgehog Mushroom, illustrates a type in which the gills or pores are replaced by teeth or spines, which cover the whole underside of the pileus, or cap. These three groups can be distinguished from each other by features that are distinct and unmistakable, so there need not be a moment’s hesitation in identifying them. The few additional forms that do not conform to any of these groups need not be mentioned here, but will be described later under their separate names.

Returning to the original definition, where a stem and pileus are the two primary elements, we must note that, in the gill-bearing fungi, this stem may have a ring or collar surrounding it near the top, or that ring may be entirely absent. This is an important feature in the discrimination of species, since it forms a part of the specific character. It is present in the Common Mushroom, but it is absent in the