but are at once distinguished from them
by their want of milk.

They are very abundant in the forests and open woods. The genus is cited
by some authors as the most natural of the agarics, but, as many of the
species very closely resemble each other, it requires careful analysis
to determine them. The plants of this genus are not volvate, and have
neither veil nor ring. The hymenophore is not separate from the trama of
the gills. Although some are pure white, the caps are usually brilliant
in coloring, but the color is very susceptible to atmospheric changes,
and after heavy rains the bright hues fade, sometimes only leaving a
slight trace of the original coloring in the central depression of the
cap.

The cap in youth is somewhat hemispherical, afterwards expanding,
becoming slightly depressed in the centre, somewhat brittle in texture;
gills rigid, fragile, with acute edge; stem thick, blunt, and polished,
usually short. The spores are globose, or nearly so, slightly rough,
white or yellowish, according to the species. In R. virescens the spores
are white, while in R. alutacea the spores are an ochraceous yellow in
tint.

A number of the species are of pleasant flavor, others peppery or acrid.
Out of seventy-two described by Cooke, twenty-four are recorded as
acrid. With some of these the acridity is said to disappear in cooking,
and a few mycophagists claim to have eaten all varieties with impunity.
We have recorded, however, some well authenticated cases of serious
gastric disturbance, accompanied by acute inflammation of the mucous
membrane, caused by the more acrid of these, notably _R. emetica_ and
_R. foetens_, and in view of this fact it would seem a wise precaution
for the _amateur_ collector to discard or at least to use very sparingly
all those which have an acrid or peppery taste, until well assured as to
their wholesomeness.

The _genus Russula_ has been divided into the following tribes or
groups:--Compactae, Furcatae, Rigidae, Heterophylla, and Fragiles. The
species _Russula (Rigidae) virescens_, illustrated in Plate I, belongs
to the tribe Rigidae. In the plants of this group, the cap is absolutely
dry and rigid, destitute of a viscid pellicle; the cuticle commonly
breaking up into flocci or granules; the flesh thick, compact, and firm,
vanishing near the margin, which is never involute, and shows no
striations. The gills are irregular in length, some few reaching half
way to the stem, the others