material agree that the forms
described constitute but a single species, and Lister makes them
identical with _D. trevelyani_ (Grev.) Fr. Rostafinski's figures, 161,
162, are a curious reproduction, evidently, of Fried. Nees von
Esenbeck's, Plate IX., Fig. 4. Massee describes a columella; Lister
says there is none. What may occasion such divergence of statement none
may say; such forms as come in so far from our western mountains have no
columella.

17. DIDERMA ASTEROIDES _List._

PLATE XVIII., Figs. 3, 3 _a_

1902. _Diderma asteroides_ List., _Jour. Bot._, XL, p. 209.
1911. _Diderma asteroides_ List., _Mycetozoa, 2nd ed._, p. 113.

Sporangia globose or ovoid-globose, the apex more or less acuminate,
sessile, sometimes narrowed at the base to a short, thick stalk, brown
or chocolate tinted, marked at the apex by radiant lines, and at length
dehiscent by many reflexing lobes revealing the snow-white adherent
inner peridium on the exposed or upper side; columella also white,
globose or depressed-globose; capillitium generally colorless, somewhat
branched, especially above; spores dark violaceous, verruculose, 10-12
mu.

Oregon, the Three Sisters Mountains; Colorado; California.

A very beautiful species, recognizable at sight; when unopened, by the
peculiar chocolate brown, the sporangia smaller than in _D. radiatum_.
When opened, the snow-white flower-like figure, flat against the
substratum, is definitive. Very near number 16 preceding; the dehiscence
more regular.

18. DIDERMA FLORIFORME (_Bull._) _Pers._

PLATE VIII., Figs. 1, 1 _a_, 1 _b_.

1791. _Sphaerocarpus floriformis_ Bulliard, _Champ._, p. 142, t. 371.
1794. _Diderma floriforme_ (Bull.) Persoon, _Roem. N. Mag. Bot._,
p. 89.

Sporangia crowded, generally in dense colonies, globose, smooth,
ochraceous-white, stipitate, the peridium thick, cartilaginous,
splitting from above into several petal-like lobes, which become
speedily reflexed exposing the swarthy spore-mass, the inner peridium
not discoverable, inseparable; stipe concolorous, about equal to the
sporangium; hypothallus, generally well developed, but thin,
membranaceous, common to all the sporangia; columella prominent, globose
or cylindric, often constricted below, and prolonged upward almost to
the top of the spore-case; capillitium of slender, delicate, sparingly
branched threads; spores dark violaceous-brown, studded with scattered
warts, 10-11 mu.

Not uncomm