teae, which some
mycologists consider somewhat out of place.

Saccardo calls its asci (sacs which contain the spores) sporangia. He
does not regard them as genuine asci, but as corresponding more to the
peridium of the _Gasteromyceteae_ and _Myxomyceteae._

Peck says that this group seems to present characters of both
Hyphomycetes and Ascomycetes, with a preponderance towards Hyphomycetes.

It is a small group, however, and since it consists wholly of
microscopic fungi, need not be farther considered in this work.

In the Ascomycetes are included the sub-families Discomycetes,
Pyrenomycetes, and Tuberacei. Of these the Discomycetes and the
Tuberacei are the only groups which contain any of the mushrooms, and
but few of these are large enough or sufficiently tender to possess
value as esculents. A good example of the first (Discomycetes) is found
in the Morel, and of the second (Tuberacei) in the Truffle.

In the Discomycetes or "disk fungi," the spores are produced in minute
membraneous sacs, each sac usually containing eight spores. These spore
sacs are imbedded in the flesh of the exterior and upper surface of the
mushroom cap.

In the four classes, Hymenomycetes, Gasteromycetes, Discomycetes, and
Tuberacei, therefore, are included all of the plants which are here
designated under the generic term of "mushrooms."

Some idea of the relative numerical value of these classes may be
obtained from the following figures given by the distinguished British
mycologist, M. C. Cooke:

"Hymenomyceteae--total number of described species 9,600
Gasteromycetae-- " " " " " 650
Discomyceteae-- " " " known " 3,500"

(The Tuberacei comprise a very small group of subterranean fungi, and
comparatively few of the species are described.)

Saccardo in his Sylloge gives a total of 42,000 described species of
fungi of all classes, including the most minute. Of these the
Hymenomycetes include by far the largest number of edible mushrooms.

The family Hymenomycetes is divided into the following six orders:
Agaricini, Polyporei, Hydnei, Thelephorei, Clavarei, Tremellini.

In the order Agaricini the hymenium is found on the under surface of the
mushroom cap, covering pleats or gills, technically called lamellae.
These gills vary in character in the different genera, being "persistent
in such as the Agaricus, Russula, and Lentinus, deliquescent (melting)
in Coprinus, B