plowing sod, in old chip piles, or
decayed wood. If one will examine these threads there will be found
small knots which will in time develop into the full grown mushroom.
Hymenomycetes are divided into six families:

1. Agaricaceae. Hymenium with gills.
2. Polyporaceae. Hymenium with pores.
3. Hydnaceae. Hymenium with spines.
4. Thelephoraceae. Hymenium horizontal and mostly on the under surface.
5. Clavariaceae. Hymenium on a smooth club-shaped surface.
6. Tremellaceae. Hymenium even and superior. Gelatinous fungi.

FAMILY 1--AGARICACEAE.

[Illustration: Figure 7.--Spore-print of Agaricus arvensis.]

In the Agaricaceae or common mushrooms, and in all other of similar
structure, the spore-producing membranes are found on the under surface
of the cap. They consist of thin lamellae, or gills, attached by the
upper edge to the cap and extending from the stem to the margin of the
cap. Very frequently that space may be entirely utilized by shorter
lamellae, or gills, intervening between the longer, especially toward the
margin of the cap. In a few species where the stem seems to be wanting,
or where it is attached to the side of the cap, the lamellae, or gills,
radiate from the point of attachment or from the lateral stem to other
parts of the circumference of the cap. Berkeley gives the following
characteristics: Hymenium, inferior, spread over easily divisible gills
or plates, radiating from a center or stem, which may be either simple
or branched.

This family includes the following genera:

1. Agaricus--Gills, not melting, edge acute; including all the
sub-genera which have been elevated to the rank of genera.

2. Coprinus--Gills deliquescent, spores black.

3. Cortinarius--Gills persistent, veil spider-web-like, terrestrial.

4. Paxillus--Gills separating from the hymenophorum and decurrent.

5. Gomphidius--Gills branched and decurrent, pileus top-shaped.

6. Bolbitius--Gills becoming moist, spores colored.

7. Lactarius--Gills milky, terrestrial.

8. Russula--Gills equal, rigid, and brittle, terrestrial.

9. Marasmius--Gills thick, tough, hymenium dry.

10. Hygrophorus--Stem confluent with the hymenophorum; gills sharp
edged.

11. Cantharellus--Gills thick, branched, rounded edge.

12. Lentinus--Pileus hairy, hard, tough; gills, tough, unequal,
toothed; on logs and stumps.

13. Lenzites--Whole plant corky; gills simple or branched.