llitium colorless, more
or less branching; spores dark purple-brown, irregularly reticulate,
9-12 mu.

Differs from _D. squamulosum_ in the reticulate epispore. Brazil.

19. DIDYMIUM LEONINUM _Berk. & Br._

1873. _Didymium leoninum_ Berk. & Br., _Jour. Linn. Soc._, XIV.,
p. 83.
1876. _Lepidoderma tigrinum_ Rost., _App. to Mon._, p. 23.
1909. _Lepidodermopsis leoninus_ v. Hoehnel, _Sitz. K. Ak. Wiss. Wien,
Math. Nat. Ks._, CXVIII., 439.

Sporangia gregarious, sub-globose, covered more or less completely with
white or yellowish deposits of crystalline lime, stipitate; stipes
short, orange or brown, containing lime, enlarged to form the globose
orange columella and often connected at base by a venulose hypothallus;
capillitium of slender threads, anastomosing, colorless at the tips;
spores violet-grey, minutely warted, 7-9 mu.

Like _Lepidoderma tigrinum_, but has different calcic crystals.

Java and Ceylon.

=3. Diderma= _Persoon_

1794. _Diderma Persoon_, _Roem. N. Mag. Bot._, I., p. 89.
1873. _Chondrioderma_ Rost. _Versuch_, p. 13, _Mon._, p. 167.
1894. _Chondrioderma_ Rost., List., _Mycetozoa_, p. 75.
1899. _Diderma Persoon_, Macbr., _N. A. S._, p. 92.

Sporangia plasmodiocarpous or distinct, sessile or stipitate; the
peridium as a rule double, the outer wall generally calcareous with the
lime granules globular, non-crystalline, the inner wall very delicate
and often, in the mature fructification, remote from the outer;
columella generally prominent.

The genus _Diderma_ is usually easy of recognition, by reason of its
double wall, the outer, crustaceous, usually calcareous, and its limits
remain substantially as originally set by Persoon. His definition is as
follows:--

"Peridium ut plurimum duplex; exterius fragile; interius pellucens,
subdistans. Columella magna, subrotunda. Fila parca latentia."--_Syn.
Meth. Fung._, p. 168.

Rostafinski changed the name of the genus to _Chondrioderma_ (_chondri_,
cartilage), seemingly at De Bary's suggestion, and seems to have
regarded Persoon's definition as applicable to those species only in
which the wall is not only plainly double, but in which the two walls
are as plainly remote from each other. More especially he esteemed a new
generic name necessary, since he regarded several included species, as
_D. spumarioides_, _D. michelii_, etc., monodermic.

Since it is doubtful whether any diderma is really monodermic, and