9. DIDERMA CINEREUM _Morg._

1894. _Diderma cinereum_ Morg., _Myx. Mi. Val._, p. 70.

Sporangia gregarious, more or less crowded or even confluent, sub-globose, only slightly depressed, ashen white; the peridium not obviously double, very smooth and thin, rupturing irregularly; hypothallus an indistinct membrane or wholly wanting; columella large, globose or hemispheric, white, the surface granulose; capillitium of very slender colored threads, the extremities pellucid, more or less branched; spores violaceous, minutely warted, 9-11 .

Growing on old wood, leaves, etc. The sporangium .3-.5 mm., thin and smooth or rugulose. This elegant little species I know only from specimens received from Mr. Morgan. It seems to be closely related to _D. spumarioides_, from which it is distinguished by its color, darker, and its smoother, or less spinulose spores. The author compares the color and external appearance to that of _P. cinereum_,--_Jour. Cin.

Soc._, XVI., p. 154.

Ohio, Pennsylvania.

10. DIDERMA HEMISPHERIc.u.m (_Bull._) _Horne._

1791. _Reticularia hemispherica_ Bull., _Cham. de Fr._, I., p. 93.

1829. _Didymium hemispheric.u.m_ (Bull.) Fr., _Syst. Myc._, III., p. 115.

1829. _Diderma hemispheric.u.m_ (Bull.) Horne., _Fl. Dan._, XI., p. 18.

1832. _Didymium michelii_ Lib., _Pl. Ard._, No. 180.

1873. _Chondrioderma michelii_ (Lib.) Rost., f.u.c.kel, _Sym. Myc._, p. 74.

Sporangia gregarious, orbicular, discoid, depressed above and often umbilicate below, stipitate or sometimes sessile, the outer peridium white, fragile, crustaceous, soon breaking about the margins, closely applied to the inner, which is delicate, cinereous, and ruptures irregularly; stipe about equal to the diameter of the sporangium, 1 mm., rather stout, calcareous but colored, brownish or alutaceous, more or less wrinkled longitudinally, the wrinkles when present forming veins on the lower surface of the sporangium; hypothallus small; columella not distinct from the thickened brownish or reddish base of the sporangium; capillitium of delicate threads, mostly simple and colorless, often scanty; spores pale violaceous, nearly smooth, 8-9 .

A very well marked species, easily recognized, at least when stipitate, by its remarkable discoid or lenticular sporangia. After the spore-dispersal, the stipes are long-persistent, surmounted by a peculiar disk representing the consolidated columella, lower sporangial wall, and expanded stem-top. Sessile specimens are like similar forms of _D. reticulatum_, but in all the gatherings before us the stipitate type is at hand to reveal the ident.i.ty of the species.

Rostafinski's figures, 131, 146, 149, and 150, adapted from Corda, exaggerate the hypothallus, but otherwise leave nothing to be desired.

As to synonymy, Bulliard has plainly the priority. His figure, t. 446, Fig. 1, can refer to nothing else, especially reenforced as it is by Sowerby, _Eng. Fung._, t. 12.

Rather rare on fallen stems of herbaceous plants, but widely distributed, New England to Oregon and Washington.

11. DIDERMA SAUTERI (_Rost._) _Macbr._

1875. _Chondrioderma sauteri_ Rost., _Mon._, p. 181.

1891. _Chondrioderma aculeatum_ Rex, _Proc. Phil. Acad._, p. 390.

Sporangia scattered, gregarious, sessile, lenticular or hemispherical, flattened above and sometimes concave or umbilicate below, dusky or yellowish white, the outer peridium papyraceous, thin, occasionally wrinkled, rupturing irregularly, remote from the inner, which is thin, delicate, semi-transparent, grayish, rarely iridescent; hypothallus none; columella irregular, sometimes small and hardly evident, rugose, with spine-like processes, the persisting bases of the capillitial threads, reddish brown; capillitium scanty, white, or colorless, simple or sparingly branched; spores dark violaceous, spinulose, 12-13 .

This is _Chondrioderma aculeatum_ Rex, _Proc. Acad. Nat. Sci. Phil._, 1891, p. 390. After careful comparison of specimens and various descriptions, especially that of Rostafinski with the type specimens of Dr. Rex, I am constrained to concur with Lister in adopting Rostafinski's name. The sporangia in the type specimens (Rex) are on moss, borne at the extreme tips of ac.u.minate or aculeate leaves, so that at first sight they appear stipitate.

Apparently rare. Maine, New York.

12. DIDERMA COR-RUBRUM _Macbr. n. s._

PLATE XVIII., Fig. 2

Sporangia gregarious cl.u.s.tered, small .5-.7 mm., sessile corrugate-plicate, especially above, snow-white, the outer peridium cartilaginous polished without and within, the inner delicate, evanescent; columella well developed, globose or clavate, anch.o.r.ed by several stout transverse trabeculae to the peridial wall, papillate, deep-red as is the peridium especially below; capillitium very delicate, sparingly branching, colorless; spores verruculose, fuliginous tinged with red, about 12 .

This curious but elegant little species is represented by a single colony collected by Professor Morton Peck in Iowa. It resembles _D.

sauteri_ but is distinguished by the plicate white wall, the stout columella with its lateral extensions, as by the more delicate spores.

On rotten wood.

13. DIDERMA OCHRACEUM _Hoffm._

1795. _Diderma ochraceum_ Hoffm., _Deutsch. Fl. Tab._ 9, 2, b.

1911. _Diderma ochraceum_ Hoffm., List., _Mycetozoa, 2nd ed._, p. 109.

Sporangia gregarious or cl.u.s.tered, .7-1 mm., sessile, globose or sometimes plasmodiocarpous, ochraceous yellow; outer wall cartilaginous with yellow deposits of lime, the inner also yellow, adherent or free; columella not distinct; capillitium simple or branching, purple-brown, hyaline at base; spores spinulose, purplish-grey, 9-11 .

Mr. Lister reports this species from Ma.s.sachusetts.

14. DIDERMA ROANENSE (_Rex_) _Macbr._

1893. _Chondrioderma roanense_ Rex, _Proc. Phil. Acad._, p. 368.

Sporangia scattered, discoidal, thin, flattened or slightly convex above, plane or plano-concave below, umber-brown, stipitate, the outer peridium smooth, brittle, rupturing irregularly, the basal fragments somewhat persistent, concrete with the inner peridium, which is pure white, except near the columella, and punctate; stipe short, variable, longitudinally ridged, jet-black; hypothallus none; columella flat, discoidal, pale ochraceous; capillitium spa.r.s.e, white or colorless, composed of simple, rarely forked, sinuous threads occasionally joined by lateral branches; spores dark violaceous, distinctly warted, 12-14 .

This species is readily distinguished by its color. The sporangia, found on rotten wood, are large, 1 mm., brown, and have thick, persistent walls. Dr. Rex considered that the species differs from other related forms not only in color, but in the well-marked discoidal columella and the jet-black irregular stipe. It is perhaps most nearly related to the following species.

Tennessee.

15. DIDERMA RADIATUM (_Linn._) _Morg._

PLATE XVIII., Fig. 8

1753. _Lycoperdon radiatum_ Linn. (?) _Sp. Pl._, 1654.

1797. _Didymium stellare_ Schrad., _Nov. Gen. Pl._, p. 21.

1801. _Diderma stellare_ (Schrad.) Persoon, _Syn._, p. 164.

1875. _Chondrioderma radiatum_ (Linn.) Rost., _Mon._, p. 182.

1894. _Diderma radiatum_ (Linn.) Morg., _Jour. Cin. Soc._, p. 66.

1899. _Diderma stellare_ Schrad., Macbr., _N. A. S._, p 104.

1911. _Diderma radiatum_ List., _Mycetozoa, 2nd ed._, p. 112.

Sporangia scattered, depressed-globose, sometimes also flattened below, stipitate, smooth or slightly corrugate, ashen or brownish, about 1 mm.

in diameter, the peridium dehiscing irregularly or somewhat radiately from above downwards, the segments reflexed, the inner layer not distinguishable, or inseparable; stipe short, stout, brownish, sometimes almost lacking; hypothallus not conspicuous, but sometimes sufficient to connect the bases of adjacent stipes; columella large, hemispherical or globose, pallid or yellowish; capillitium abundant, of slender generally simple, colored threads, paler at the furcate tips; spores dark violaceous, minutely roughened, 8-11 .

Rare on rotten logs in the forests; September. Easily recognized by the short-stiped, ashen sporangia which before dehiscence indicate by delicate tracings the lines which subsequent cleavage is to follow. In texture the peridium resembles that of _D. floriforme_.

Pennsylvania, Ohio, Iowa, Virginia, Colorado, Washington, Oregon; Europe generally.

The Linnaean description on which to base the specific name _D. radiatum_ is wholly inadequate. It appears also by the testimony of Linne _fils_, that _L. radiatum_ Linne is a lichen! and the name is so applied by Persoon. But in the Linnaean herbarium preserved at London, _teste_ Lister, the original type of _Lycoperdon radiatum_ L. may yet be seen!

to the confusion of _fils_, Persoon, and other followers of Schrader all, and our stellar species becomes radiate now, let us hope for long!

16. DIDERMA TREVELYANI (_Grev._) _Fr._