AEthalium composed of numerous very
slender sporangia, closely compacted into a single stratum, and seated
on a conspicuous silvery hypothallus; the surface ochroleucous, honey
color or olivaceous. The sporangia are typically hexangular when the
lateral faces disappear, leaving at the edges six simple triangular
threads, extending from the angles of the hexagonal apex downward to the
base. Spores in the mass ochraceous, yellowish or brownish, globose,
minutely warted, 8-10 mic. in diameter.

Growing on old wood. AEthalium somewhat circular, or often quite
irregular in shape, 1 to several centimeters in extent, the individual
sporangia nearly 1 mm. in height, but scarcely .1 mm. in thickness.
Deviations from the typical form of the sporangia sometimes occur, they
are not seldom pentangular, and I have seen the apices quadrangular,
with only four threads, or even triangular, and with but three; the
threads, too, are said occasionally to branch and anastomose.
_Reticularia plumbea_, Fries, S. M. III, 88; and _Ostracoderma
spadiceum_, Schw., N. A. Fungi No. 2,381.

III. CRIBRARIA, Pers. Sporangia simple, globose or obovoid, stipitate,
often cernuous; the wall regularly thickened on the inner surface in two
ways, the lower basal portion by radiating ribs consisting of minute
brown granules, the upper part by slender threads combined into a
network of polygonal meshes; the basal portion of the membrane is
commonly persistent with its thickening and is called the _calyculus_,
the upper part nearly always disappears from the network at maturity;
there are usually nodules of the brown granules at the angles of the
network. Spores globose, purple, brown, ochraceous.

_a. Sporangium, large._

1. CRIBRARIA ARGILLACEA, Pers. Sporangia globose or obovoid, stipitate
or nearly sessile, standing close together on a thin and evanescent
hypothallus; the wall quite firm, silvery-shining, the greater portion
persistent, breaking away about the apex; calyculus small, the brown
radiating ribs soon passing into a network of polygonal meshes, the
threads with irregular granulose-thickened portions at intervals
throughout their whole extent. Stipe very short, erect, brown. Spores in
the mass argillaceous, globose, 5-7 mic. in diameter.

Growing in large irregular patches on rotten trunks. Sporangia .6-.8 mm.
in diameter, the stipe always much shorter than the sporangium,
sometimes nearly obsolete. The resemblance of this species to some