wn; the peridium rather thick, yellow within, the dehiscence
circumscissile; capillitium scanty, of slender, sparingly branched
filaments, the surface minutely roughened, warted or spinulose;
spore-mass yellow; by transmitted light pale yellow, 9-11 mu.

Differs from the preceding by the much smaller size of the sporangia,
different color and habit. The sporangia, while depressed, still
maintain considerable rotundity; they are occasionally quite spherical,
and then of very uneven size, hardly in contact. In some cases the
plasmodium before maturing seems to assume the form of a plasmodiocarp,
which, by transverse fission at intervals, forms the curious four-sided
conceptacles. At other times the plasmodium assumes the shape of a flat
cushion or plate, which then subdivides into minute polygonal segments.
This form has been known some years to collectors, and, if named at all,
has been called _P. irregularis_. Lister, _l. c._, assures us that
Berkeley's type "is typical _P. depressa_."

Not common. Pennsylvania, Ohio, Illinois, Missouri.

3. PERICHAENA CORTICALIS (_Batsch_) _Rost._

PLATE II., Figs. 1, 1 _a_, 1 _b_.

1783. _Lycoperdon corticale_ Batsch, _Elench. Fung._, p. 155.
1875. _Perichaena corticalis_ (Batsch) Rost., _Mon._, p. 293.
1817. _Perichaena populina_ Fries, _Symb. Gast._, p. 12.

Sporangia sessile, gregarious, flattened, hemispherical; peridia simple,
opening by a lid; dehiscence circumscissile, the upper part chestnut
brown, the lower almost black; capillitium feebly developed, smooth,
attached to the lid and usually coming away with it, bringing the
brilliantly yellow spore-mass, and leaving a delicate, shining cupule
adherent to the substratum; spores yellow, nearly smooth, 10-12 mu. On
and under the bark of dead elms of various species.

A very handsome little species occuring rarely with us, or perhaps
overlooked by virtue of its protective coloration. Found sometimes on
the inner side of the bark where the latter has separated, but not yet
wholly parted company with the wood. In such situations the tiny
sporangia are so nearly quite the color of the moist substratum as to
escape all but the closest scrutiny. The dehiscence is very remarkable,
characteristic, beautiful. Black, brown, chestnut, and gold are
harmoniously blended, in the opening coffers. Prior to maturity the
future line of fission is plainly indicated by the difference in color.

This is clearly the species found by