known, the genus may be left with its historic
species,--montotypic.

LEOCARPUS FRAGILIS (_Dickson_) _Rost._

PLATE VIII., Figs. 3, 3 _a_, 3 _b_.

1785. _Lycoperdon fragile_ Dickson, _Fasc. Pl. Crypt. Brit._, I.,
p. 25.
1795. _Diderma vernicosum_ Persoon, _Ust. Ann. Bot._, XV., p. 34.
1809. _Leocarpus vernicosum_ Link, _Diss._, I., p. 25.
1875. _Leocarpus fragilis_ (Dicks.) Rost., _Mon._, p. 132.

Sporangia gregarious or clustered, sessile or stipitate, obovoid, rusty
or spadiceous-yellow, shining; peridium opening at maturity in somewhat
stellate fashion; stipe filiform, white or yellow, weak and short;
spores dull black, spinulose, 12-14 mu.

A common species, distributed through all the world, Iowa to Tasmania.
Recognizable at sight by the form and color of the sporangia. In shape
and posture these resemble the eggs of certain insects, and, occurring
upon dead leaves, generally where these have drifted against a rotten
log, they might perchance be mistaken for such structures. With no other
slime-moulds are they likely to be confused. The outer peridium opens
irregularly, or more rarely stellately. At centre of the capillitium is
a calcareous core. The plasmodium is yellowish white, spread in rich and
beautiful reticulations. _N. A. F._, 1123.

A plasmodiform gathering of this species which will be mistaken for an
entirely different thing, is yellow, sessile, and has _adherent_ spores;
looks like a badhamia, but is after all a leocarpus and probably belongs
here. The spores are irregularly clustered and the badhamioid section of
the capillitium seems now dominant.

California.

B. DIDYMIACEAE

=Key to the Genera of the Didymiaceae=

1. Fructification aethalioid 1. _Mucilago_

2. Fructification plasmodiocarpous, or forming more
often distinct sporangia.

_a._ Calcareous deposits crystalline, stellate 2. _Didymium_

_b._ Calcareous deposits amorphous, peridium double 3. _Diderma_

_c._ Calcareous deposits in form of scattered
scales 4. _Lepidoderma_

_d._ Peridium double, the outer gelatinous 5. _Colloderma_

=1. Mucilago= (_Mich._) _Adans._

1729. _Mucilago_ Micheli, _Nov. Pl. Gen._, in part.
1763. _Mucilago_ (Mich.) Adanson, _Fam. des Pl._, II., p. 7.
1791. _Spumaria_ Pers. in Gmelin, _Syst. Nat._, II., p. 1466.

Fructification aethalioi