iii. Peridium chocolate without,

inside white 17. _D. asteroides_

2. Sporangia stipitate.

_a._ Peridium pallid, smooth 18. _D. floriforme_

_b._ Peridium white, rugulose 19. _D. rugosum_

1. DIDERMA EFFUSUM (_Schw._) _Morgan._

1831. _Physarum effusum_ Schw., _N. A. F._, p. 257. 1896. _Diderma effusum_ (Schw.) Morg., _Jour. Cin. Soc._, p. 71. 1899. _Diderma effusum_ (Schw.) Morg., Macbr., _N. A. S._, p. 94. 1899. _Diderma reticulatum_ Rost., Macbr., _N. A. S._, p. 95. 1911. _Diderma effusum_ Morg., Lister, _Mycetozoa, 2nd ed._, p. 102.

Fructification plasmodiocarpous, reticulate, creeping, applanate and generally widely effused, white; the peridium thin, cinereous, covered by a delicate, white, calcareous crust; the columella simply the base of the plasmodiocarp, thin alutaceous; the capillitium pale, consisting of short threads somewhat branched toward their distal extremities; spores smooth, pale violaceous, 8-10 mu.

This is _Physarum effusum_ Schw., _vid. N. A. F._, No. 2297. It is reported by Morgan from Ohio, and we have one specimen from eastern Nebraska, so that it is probably of general distribution in the eastern United States.

This species was in the previous edition distinguished from the Rostafinskian _P. reticulatum_ with spores a little smaller, 6-8 mu, and with a much stronger tendency to the formation of definite sporangia, elongate indeed and branching but often globose or depressed globose. This we may know as,

VAR. RETICULATUM Rost.

1875. _Chondrioderma reticulatum_ Rost., _Mon._, p. 170. 1894. _Diderma reticulatum_ (Rost.) Morg., _Jour. Cin. Soc._, p. 71.

Sporangia gregarious, generally rounded, not much depressed, flat, sometimes, especially toward the margin of a colony, elongate, venulose or somewhat plasmodiocarpous, dull white, the inner peridium ashen or bluish, remote from the calcareous crust, which is extremely fragile, easily shelling off; columella indistinguishable from the base of the sporangium, thin, alutaceous; capillitium of short, generally colorless, delicate, sparingly branching or anastomosing threads perpendicular to the columella; spores black in mass, by transmitted light violet-tinted, smooth, 6-8 mu.

Perhaps our most common form. Found in fall on dead twigs, leaves, etc. Recognized by its rather large, white, depressed or flattened sporangia tending to form reticulations, and hence suggesting the name. The lines of fruiting tend to follow the venation of the supporting leaf; where the sporangium is round, the columella is a distinct rounded or cake-like body; where the fruit is venulose, the columella is less distinct.

By these rounded forms we pass easily, as by a gate, to _D. hemisphericum_, which, when wholly sessile, differs still in greater diameter of the sporangia and in having somewhat larger spores. Usually in such case the compared colony will show somewhere a very short and stout but very real stipe supporting the discoid fruit.

Rostafinski divided the genus _Chondrioderma_, i. e. _Diderma_, into three sections:--

_Monoderma_ to include those species in which the calcareous crust is less distinct or connate with the true peridium.

_Diderma_, in which the two structures were plainly separate.

_Leangium_, used as in the present work. In his first section Rostafinski placed _C. reticulatum_ and _C. michelii_; in the second, _C. difforme_ and _C. calcareum_.

Lister has examined Rostafinski's type of _C. reticulatum_ and declares that it has the usual didermic characters. Hence there is no doubt that our small-spored American specimens are covered by Rostafinski's description, No. 72. On the other hand, Lister makes _C. difforme_ (Pers.) Rost. a _Didymium_, by its crystalline coat. That species therefore is removed from consideration in this connection. _C. calcareum_ remains as applicable to American forms having the spores 10-12 mu, but according to the author of the species the capillitium is abundant and definitive. Unhappily the type of _C. calcareum_ is lost (Lister, _Mon._, p. 95), so that there is no other means of verification than the description and Rostafinski's figure. Under these circumstances we consider the name _calcareum_ inapplicable to any American forms we have so far seen. See next species. As to the American species which have been distributed as _C. calcareum_ (Lk.) Rost., they are, so far as seen, referable to _D. reticulatum_ (Rost.), Morg. Here also belongs No. 1217, Ellis, _N. A. F._

New York, Pennsylvania, Ohio, Iowa, Nebraska. Probably to be found throughout the eastern United States.

2. DIDERMA SPUMARIOIDES _Fries_.

1829. _Diderma spumarioides_ Fries, _Syst. Myc._, III., p. 104. 1833. _Physarum stromateum_ Link., _Handb._, III., p. 409. 1876. _Chondrioderma stromateum_ (Lk.) Rost., _App._, p. 18.

Sporangia sessile, crowded, spherical, or by mutual pressure irregular, white; the peridium plainly double, but the layers adhering, the outer more strongly calcareous, but very frail, almost farinaceous; hypothallus more or less plainly in evidence, white or pale alutaceous; columella distinct, though often small, globose, yellowish; capillitium variable in quantity, sometimes abundant, brown, somewhat branching and anastomosing outwardly, the tips paler; spores minutely roughened, dark violaceous, about 10 mu.

This species has the outward seeming of a didymium, but is plainly different as that genus is here defined, since the calcareous crust, although inclined to be pulverulent, is made up of minute granules, not crystals, of lime. The hypothallus is sometimes hardly discoverable, anon well developed, out-spread, rugulose, far beyond the limits of the fructification. In his _Monograph_, p. 175, Rostafinski includes here _Physarum stromateum_ Link. In the Appendix he is inclined to raise Link's form to the dignity of a distinct species, basing the diagnosis upon the superposition of the sporangia in certain cases, a feature entirely unknown to Link's description and of extremely uncertain value, since by their crowding the sporangia are liable always to be pushed above each other. We therefore regard _C. stromateum_ (Link) Rost. as a synonym of the present species, as the description, Link, Handb., III., 409, indicates, so far as it goes.

3. DIDERMA SIMPLEX (_Schroet._) _Lister._

1885. _Chondrioderma simplex_ Schroet., _Krypt. Fl. Schles._, III., 1, p. 123. 1911. _Diderma simplex_ List., _Mycetozoa, 2nd ed._, p. 107.

"Plasmodium bright yellowish brown." Sporangia gregarious, sessile, globose or depressed globose, .3-.5 mm., or anon plasmodiocarpous, brown or brick-red when fresh, becoming paler, ochraceous, etc.; hypothallus everywhere in evidence; columella ill-defined; capillitium scanty, the threads delicate, pale, branching as they join the peridial wall; spores dull violaceous, slightly roughened, 8-10 mu.

A rather crude, primitive representative of this beautiful genus. The inner peridium seems to be lacking,--a comfort to Rostafinski! Rare. Our best specimens are from New Jersey, by courtesy of Dr. C. L. Shear. These went to fruit on leaves and branches of _Vaccinium_. It seems to affect the heather of Europe, moorland, etc. I have also specimens from the herbarium of the lamented Dr. Rex. These are more plasmodiocarpous, but open beautifully by a median fissure as in _Physarum sinuosum_ Bull. In no American gathering that I have examined does the capillitium show calcareous thickenings as described by the British text.

4. DIDERMA GLOBOSUM _Persoon._

PLATE VII., Figs. 5, 5 _a_.

1794. _Diderma globosum_ Pers., _Roem. N. Mag. Bot._, I., p. 89. 1875. _Chondrioderma globosum_ (Pers.) Rost., _Mon._, p. 180.

Sporangia more or less closely gregarious, sessile, globose or by mutual pressure prismatic or polyhedral, white, the outer wall smooth, polished, crustaceous, fragile, far remote from the inner, which is thin, smooth, or rugulose, iridescent blue; hypothallus usually pronounced and spreading beyond the sporangia, sometimes scanty or lacking, columella variable, sometimes very small, inconspicuous, sometimes large, globose, ellipsoidal, even pedicellate; capillitium abundant, brown or purplish brown, branching and occasionally anastomosing to form a loosely constructed superficial net; spores globose, delicately spinulose, 8 mu.

This species seems rare in this country. We have specimens from Iowa. It is distinguished by small spores and generally snow-white color. Lister has thrown doubt upon Rostafinski's definition of this form--_Mycetozoa_, p. 78. Almost everything distributed in the United States under this name belongs in the next species. Reported also from Ohio,--_Morgan._ Washington. But:--it should be found in Europe, where first described!

There are two ways to meet the difficulty. In the first place it seems probable that a small-spored form really hides somewhere in Europe. The difference between the _Monograph_ measurement and the size admitted for _D. crustaceum_ Pk., evidently considered by Mr. Lister as type and so used in his illustration, Pl. 85, is too great to be esteemed merely an error. That added .3 (Rost.) indicates caution, the average of several measurements. Our _D. globosum_ may represent what the _Monograph_ describes.[32] In the second place we may as American students mistake larger and more globular forms of something else, of _D. spumarioides_ Fr., whose spores are but little larger; or of _D. effusum_ (Schw.) Morg., where the flattened plasmodiocarps anon splatter out to globose drops of polished whiteness, and whose spores are 8 mu. But even here the chances of error are small. In the species last named the columella or sporangial base is alutaceous, not white; in Fries' species, while the columella if present may be white, the peridial walls are different, difficult to distinguish.

For these reasons, _D. globosum_ Pers. may stand, waiting further light from Europe.

5. DIDERMA CRUSTACEUM _Peck._

PLATE VII., Fig. 7

1871. _Diderma crustaceum_ Peck, _Rep. N. Y. Mus._, XXVI., p. 74. 1889. _Chondrioderma crustaceum_ (Peck) Berl., _Sacc._, VII., p. 373.

Plasmodium at first watery, colorless, becoming at length milky white; sporangia closely crowded or superimposed, in a cushion-like colony, creamy white, globose, imbedded in the substance of the hypothallus, the outer peridium smooth, delicate, crustaceous, fragile, remote from the blue iridescent inner membrane; hypothallus prominent; columella variable, generally present, globose; capillitium dark-colored, the threads branching and combining to form a loose net; spore-mass black, spores by transmitted light dark violaceous, delicately roughened, 12-15 mu.

Common. Readily to be distinguished from the preceding by the larger spores and more crowded habit. New England west to Nebraska.

The didermas are generally delicately beautiful. The outer wall in the present species is like finest unglazed china, softly smooth, and yet not polished, often absolutely white, with porcellanous fracture. An inter-parietal space separates the outer from the inner wall, so that the former may be broken, bit by bit, without in the least disturbing the underlying structure. The inner wall is ashen or gauzy iridescent green, sending back all colors in reflected light. The spores are violet, deeply so when fresh, the capillitium strong and likewise tinted; the columella passing down and blending with the common snow-white hypothalline base. The distinct habits of the two species are represented in Figs. 5 and 7. In the one the distinct sporangia are associated but not crowded; in the other all are massed together in quite aethalioid fashion, forming circumambient, chalky masses of considerable size, 2 or 3 cm., overcrowded, superimposed, where the sporangia are regular in shape and size by reason of mutual pressure. The plasmodium develops in forests and orchards, among decaying leaves, but is inclined to rise as maturity draws near, to ascend some twig erect, or the stem of a living plant to the height of several inches where the sporangia at length appear "heaped and pent", an encircling sheath, conspicuous after the fashion of a spumaria for which it is indeed sometimes mistaken.

6. DIDERMA LYALLII (_Massee_) _Macbr._

PLATE XVIII., Figs. 5 and 5 _a_

1892. _Chondrioderma lyallii_ Massee, _Mon._, p. 201. 1894. _Chondrioderma lyallii_ Mass., List., _Mycetozoa_, p. 81. 1899. _Diderma lyallii_ Mass., Macbr., _N. A. S._, p. 99. 1911. _Diderma lyallii_ List., sub-species, _Mycetozoa, 2nd ed._, p. 105.

Sporangia obovate, more or less closely crowded, white, stipitate, about 1 mm. in diameter, the outer peridium firm, stout, encrusted, especially above, with granular masses of lime, the inner well developed, more or less cartilaginous, opaque, yellow or buff-colored; hypothallus well developed, venulose, white, passing up unchanged to form the short, stout stipe and lower outer peridium; columella prominent, half the height of the sporangium, brown; capillitium of short, brown threads, rigid, much branched, forming a net, widened irregularly and especially at the net-nodes; spore-mass black, spores by transmitted light bright brown, rough, 15-17 mu.

A very distinct species; large, fine, showy sporangia in more or less crowded clusters spring from a snow-white, common hypothallus. First reported from western Canada. Our first specimens were collected by the late Mr. Charles Irish, on the eastern slopes of the Sierras, in Nevada; now coming in abundantly from all the western mountains to the Pacific.

7. DIDERMA TESTACEUM (_Schrad._) _Pers._

PLATE VII., 4, 4 _a_, and 4 _b_.

1797. _Didymium testaceum_ Schrad., _Nov. Gen. Plant._, p. 25. 1801. _Diderma testaceum_ Persoon, _Syn._, p. 167. 1873. _Chondrioderma testaceum_ (Schrad.) Rost., _Vers._, p. 13. 1874. _Diderma mariae-wilsoni_ Clinton, _Rep. N. Y. Mus._, XXVI., p. 74. 1899. _Diderma testaceum_ (Schrad.) Pers., Macbr., _N. A. S._, p. 99. 1911. _Diderma testaceum_ Pers., List., _Mycetozoa, 2nd ed._, p. 106.

Sporangia gregarious, sessile, depressed-spherical or sometimes elongate, small, 1 mm. or less, rose-white, smooth, the outer peridium crustaceous, rather thick and persistent, polished, slightly raised above the inner, which is dull ashen and more or less wrinkled; hypothallus none; columella prominent, hemispherical in the typical rounded forms, slightly rough, reddish or reddish alutaceous; capillitium usually abundant, of slender, delicate pale or colorless threads, little branched, and smooth; spores violaceous-brown, minutely roughened, 8-9 mu.

A very beautiful species occurring at the same time as the preceding and in similar situations. All our specimens from the west are on dead leaves of oak; some eastern gatherings are on moss. Easily recognized when fresh by its delicate pink or roseate color; weathered specimens are white, and might be confused with forms of _D. reticulatum_, but the sporangia in the present species are less flattened and only rarely in special situations run off to linear or plasmodiocarpous shapes characteristic of _D. reticulatum_.

Not common, although widely distributed from east to west. New England, New York, New Jersey, South Carolina, Ohio, Illinois, Iowa, Nebraska, California (_Harkness_), Washington, Oregon.

8. DIDERMA NIVEUM (_Rostafinski_) _Macbr._

PLATE XVIII., Fig. 11 and 11 _a_

1875. _Chondrioderma niveum_ Rost, _Mon._, p. 170. 1877. _Diderma albescens_ Phillips, _Grev._, V., p. 114.

Sporangia gregarious, scattered, or more often crowded, sessile, depressed-spherical, sometimes ellipsoidal or elongate, white, the outer peridium crustaceous, chalky, smooth and fragile, the inner distinct, delicate, ochraceous; hypothallus scant or none; columella well developed, globose or hemispherical, orange-tinted or ochraceous; capillitium abundant, made of threads of two sorts, some purplish or dusky, with pale extremities, uneven, others more delicate and colorless, and with wart-like thickenings, all sparingly branched; spores violet-brown, minutely roughened, 9-10 mu.

This species is not common. From Colorado we have fine specimens typical in every way. Specimens from Washington are flat so far as at present at hand; probably represent _D. deplanatum_ (R.) List., which the last named author regards as varietal of the present species, entering it and _D. lyallii_ as sub-species 2 and 1 respectively. _D. deplanatum_ may perhaps be best so disposed of; but _D. lyallii_ is distinguished at sight, as well as by microscopic characters, spores nearly twice as great, rougher and different in color.

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 mu.

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 HEMISPHERICUM (_Bull._) _Horne._

1791. _Reticularia hemispherica_ Bull., _Cham. de Fr._, I., p. 93. 1829. _Didymium hemisphericum_ (Bull.) Fr., _Syst. Myc._, III., p. 115. 1829. _Diderma hemisphericum_ (Bull.) Horne., _Fl. Dan._, XI., p. 18. 1832. _Didymium michelii_ Lib., _Pl. Ard._, No. 180. 1873. _Chondrioderma michelii_ (Lib.) Rost., Fuckel, _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 mu.

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 identity 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 mu.

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 acuminate 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 clustered, 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, anchored 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 mu.

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 clustered, .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 mu.

Mr. Lister reports this species from Massachusetts.

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 sparse, white or colorless, composed of simple, rarely forked, sinuous threads occasionally joined by lateral branches; spores dark violaceous, distinctly warted, 12-14 mu.

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 mu.

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._

1825. _Leangium trevelyani_ Grev., _Scot., Cr. Fl._, Tab. 132. 1829. _Diderma trevelyani_ (Grev.) Fr., _Syst. Myc._, III., p. 105. 1875. _Chondrioderma trevelyani_ (Grev.) Rost., _Mon._, p. 182. 1877. _Diderma geasteroides_ Phill., _Grev._, V., p. 113. 1877. _Diderma laciniatum_ Phill., _Grev._, V., p. 113.

Sporangia scattered, globose or nearly so, smooth or verruculose, reddish-brown or rufescent, sessile or short-stipitate, the outer peridium firm, splitting more or less regularly into unequal, revolute, petal-like lobes which are white within, the inner not distinguishable as such; stipe, when present, equal, furrowed, concolorous; columella small or none; capillitium abundant, the threads rather rigid, purple or purplish brown, branching and anastomosing, more or less beaded; spores dark, violaceous brown, spinulose, 10-13 mu.

In 1876, Harkness and Moore collected in the Sierra Nevada Mountains of California, forms of _Diderma_ which are described by Phillips, _Grev._, V., p. 113, as _D. geasteroides_ and _D. laciniatum_. English authorities who have examined the 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 uncommon, especially on rotten oak logs. Easily recognized by the peculiar form of the fruit, spherical before dehiscence, floriform after. Unlike most species, this form often fruits in dark places, in the interior of a log, even in the ground.

New England, Ontario to Iowa and Nebraska, and south.

19. DIDERMA RUGOSUM (_Rex_) _Macbr._

PLATE XVIII., Fig. 10.

1893. _Chondrioderma rugosum_ Rex, _Proc. Phil. Acad._, p. 369.

Sporangia gregarious, scattered, white or ashen, rugulose over the whole surface, the ridges marking the lines of subsequent rupture or dehiscence, the peridium thin papyraceous, stipitate; stipe well developed about equal to the sporangium, subulate, almost black; hypothallus none; columella distinct, generally white, sometimes small, globose, sometimes penetrating the sporangium, to one-half the height; capillitium white or colorless, the filaments freely forked and combined by lateral branches into a loose network attached to the columella and basal wall below and the upper sporangial wall above; spores violaceous-brown, warted, 8-10 mu.

This species is well designated _rugosum_, and is recognizable at sight by its wrinkled, areolate surface. Related to _D. radiatum_ in the prefigured dehiscence, but otherwise very distinct. Liable to be overlooked as a prematurely dried physarum. Rare. Plasmodium gray.

North Carolina, Iowa.

=4. Lepidoderma= _DeBary_

1858. _Lepidoderma_ DeBy., MS. Rost., _Versuch_, p. 13.

Sporangia stalked or sessile; peridium cartilaginous, adorned without with large calcareous scales, superficial or shut in lenticular cavities; capillitium non-calcareous.[33]

=Key to Species of Lepidoderma=

_A._ Sporangia stipitate, stipe brown 1. _L. tigrinum_

_B._ Sporangia sessile, plasmodiocarpous, spores 10-12 mu 2. _L. carestianum_

_C._ Sporangia plasmodiocarpous, spores 8-10 mu 3. _L. chailletii_

1. LEPIDODERMA TIGRINUM (_Schrad._) _Rost._

PLATE XIV., Fig. 7.

1797. _Didymium tigrinum_ Schrad., _Nov. Gen. Plantarum_, p. 22. 1873. _Lepidoderma tigrinum_ (Schrad.) Rost., _Versuch_, p. 13.

Sporangia scattered, rather large, hemispherical-depressed, stipitate, umbilicate beneath, the peridium shining, olivaceous or purplish, tough, covered more or less abundantly with angular scales; the stipe stout, furrowed, dark brown, but containing calcareous deposits withal, tapering upward, and continued within the peridium as a pronounced more or less calcareous columella; hypothallus more or less prominent, yellowish or brownish; capillitium dark, purplish-brown, of sparingly branching threads radiating from the columella; spores dull purplish-brown, minutely roughened, 10-12 mu.

A singular species, rare, but easily recognized by its peculiar, placoid scales, large and firmly embedded in the peridial wall. The internal structure is essentially that of _Diderma_ or _Didymium_. The species occurs in hilly or mountainous regions, on moss-covered logs. The plasmodium pale yellow, some part of it not infrequently remains as a venulose hypothallus connecting such sporangia as are near together.

New England to Washington and Oregon; Vancouver Island.

2. LEPIDODERMA CARESTIANUM (_Rabenh._) _Rost._

1862. _Reticularia carestiana_ Rabenh., _MS. Fung. Eur. exsic._, No. 436. 1875. _Lepidoderma carestianum_ (Rabenh.) Rost., _Mon._, p. 188. 1891. _Amaurochaete minor_ Sacc. & Ell., _Mich._, II., p. 566.

Fructification in the form of flat, pulvinate plasmodiocarps, or, anon, sporangiate, the sporangia sessile, sub-globose, ellipsoidal, elongate, irregular, confluent, yellowish-grey, the peridium covered more or less completely with dull white, crystals or crystal-like scales; columella, where visible, yellowish-brown, calcareous; capillitium, coarse, rigid, more or less branched and united, or colorless, delicate, forming a definite net; spores distinctly warted, purple 10-12 mu.

This is a most remarkable species. The sporangiate forms little resemble those distinctly plasmodiocarpal. In the former the calcic scales and crystals are distinct and quite as in _L. tigrinum_; in the latter they are cuboid, irregular. The wall of the peridium in the plasmodiocarps at hand is black, and the covering accordingly shows white; in the sporangial forms the wall is brown, and the scales have a yellow tinge as if tinged with iron. In the sporangial presentation the capillitium is intricate delicate; in the plasmodiocarp, rigid, dark-colored, etc. This looks like a didymium and in so far justifies the opinion of earlier students. Fries, of course, includes all these things with the didymiums, and _D. squamulosum_ probably often sheltered them under extended wing.

_Didymium granuliferum_ Phill., _Grev._, V., p. 114, from California is by European authors referred here. The capillitium carries calcareous crystalline deposits in special vesicles and the spores show remarkable variation in unusual size--15-30 mu.[1]

Should probably be entered _Lepidoderma granuliferum_ (Phill.) Fr., spores 15-18 mu.[34]

Utah,--Harkness.

3. LEPIDODERMA CHAILLETII _Rost._

PLATE XVIII., Figs. 6, 6 _a_, 6 _b_.

Sporangia distinct, coalescent or plasmodiocarpous, large, when isolated 1-1.5 mm., dull drab in color, very sparsely sprinkled with white tetrahedral or irregular scales; the peridium thin, more or less translucent, rugulose, dull brown, persistent; columella none; capillitium abundant, under the lens purple-brown, sparingly branched, even, stout, rigid, no calcareous deposits nor vesicles; spores 8-10 mu, minutely warted, fuliginous.

Yosemite Canyon, California, _Prof. B. Shimek._

This is, no doubt, similar to _L. carestianum_ but differs in the size and habit of the sporangia, and in the fact that the capillitium is uniform throughout, whatever the style of fructification, and in the size, color, and surface characters of the spore.

Evidently not _Didymium granuliferum_ Phill. Both will, no doubt, be again collected, and we shall then have much needed light.

Nor is this quite Rostafinski's species as cited. The spores are much smaller; Rostafinski says 10-12 or more, and calls for a distinctly netted capillitium, the surface strongly marked by abundant calcareous crystals. Ours may be a different thing.

=5. Colloderma= _G. Lister_

1910. _Colloderma, Jour. of Botany_, XLVIII., p. 312.

Peridium double; the outer gelatinous, the inner membranaceous; capillitium intricate, limeless.

COLLODERMA OCULATUM (_Lipp._) _G. Lister._

1894. _Didymium oculatum_ Lipp., _Verh. Zo-Bot. Ges. Wien_, XLIV., p. 74. 1910. _Colloderma oculatum_ (Lipp.) G. List., _Jour. Bot._, XLVIII., p. 312.

Sporangia gregarious, globose, or sub-globose, sessile or short-stipitate, olivaceous or purplish-brown, smooth and shining, the outer peridium gelatinous, thickened by moisture, hyaline; stipe dark brown; columella none; capillitium as in _Didymium_ purplish-brown, colorless at the tips; spores spinulose, fuscous, about 12 mu.

New Hampshire, Europe.

Our specimens from the late Dr. W. G. Farlow who collected it in New Hampshire. Swollen by immersion in water the sporangia take on an eye-like appearance, oculate, etc.

=EXTRA-LIMITAL=

PHYSARINA _von Hoehnel._

1909. _Physarina_ von Hoehnel, _Akad. Wiss. Wien; Math-nat. KL._, CXVIII., p. 431.

Sporangium wall rough with blunt spine-like processes, otherwise as _Diderma_.

One species, _op. cit._, p. 432, _P. echinocephala_ v. Hoehn.

Java. Might as well be called _Diderma echinocephalum_, one would think. Structure is that of _Leangium_. The striking character is a surface modification of the outer peridium, according to the description.

ORDER II

=STEMONITALES=

Capillitium present, thread-like, arising in typical cases from a well-developed columella; spores in mass, black or violet-brown, more rarely ferruginous.

=Key to the Families of Stemonitales=

_A._ Fructification aethalioid, capillitium poorly defined; columella rudimentary or none AMAUROCHAETACEAE

_B._ Fructification of distinct sporangia, capillitium well defined; the columella generally prominent, long and abundantly branched throughout STEMONITACEAE

_C._ Sporangia distinct; capillitium developed chiefly or only, from the summit of the columella LAMPRODERMACEAE

_A._ AMAUROCHAETACEAE

Fructification aethalioid, an inch or two in diameter, in form varying with the habitat and place; capillitium dendroid, consisting of rather stout branches which rise irregularly more or less vertically from the hypothallus, branch repeatedly, often anastomose to form a network, especially toward the periphery; spores black.

A single genus--

=1. Amaurochaete= _Rostafinski_

1873. _Amaurochaete_ Rost., _Versuch._, p. 8.

The genus _Amaurochaete_ as defined by Rostafinski and the genus _Reticularia_ as represented by _R. lycoperdon_ Bull. stand, the expression, perhaps, of not dissimilar histories. Whether in regressive or progressive series, each to-day presents a case of arrested development. Each in aethalioid fructification, reveals a mass of involved individual (?) sporangia, so imperfectly developed that their outlines can be inferred rather than anywhere, with absolute definiteness, certainly ascertained. Perhaps, because similar sporangia in the group to which either belongs, do come under other circumstances, to more perfect individual form and function--perhaps for this reason we may look upon these aethalia as exhibiting a suspended performance; the sporangia have failed to go forward to what was evidently a possible, though apparently not an essential destiny in form and figure. For the care and dispersal of the spores, achievement must surely be somewhat impaired. Whatever the measure of such inefficiency, among the _Stemonitales Amaurochaete_ shows the acme, as _Reticularia_ among the brown-spored forms.

In _Amaurochaete_ the individuality of anything like separate sporangia is less clear. The view afforded, however, by a good vertical section of a well-developed colony or cushion is interestingly arborescent. Ragged, dendroid stems arise, dissipated above into a network most intricate, a "pleached arbor" if you please. The resemblance of the overhead net to that presented by a stemonitis or comatricha is very striking.

=Key to the Species of Amaurochaete=

_A._ Capillitium rigid, irregular spores rough 1. _A. fuliginosa_ _B._ Capillitium soft, woolly, cincinnate, spores as in _A_ 2. _A. tubulina_

1. AMAUROCHAETE FULIGINOSA (_Sowerby_) _Macbr._

PLATE V., Figs. 8, 8 _a_.

1803. _Lycoperdon fuliginosum_ Sow., _Eng. Fung._, t. 257. 1805. _Lycogala atrum_, Alb. & Schw., _Consp. Fung._, p. 83. 1875. _Amaurochaete atra_ (Alb. & Schw.) Rost., _Mon._, p. 211.

Fructification aethalioid, varying in form and size, if on the upper side of the substratum, pulvinate, if below pendent and almost stipitate, covered with a delicate cortex, at first shining, soon dull, black, fragile, and early dissipated; hypothallus long-persisting, supporting the capillitium, which is extremely variable, irregular, and for its perfection dependent upon the form assumed by the aethalium, and the conditions of weather, etc., under which it matures, sometimes, especially when prostrate, in a very much depressed aethalium, spreading into long fibrous threads, again under better conditions rising in columella-like forms, supporting a peripheral net; spores dark brown or black, irregularly globose, spinulose, 12.5-15 mu.

Common in Europe, and probably not uncommon in this country wherever pine forests occur. Specimens before us are from New England and New York, Ohio, Carolina, Colorado. Canada.

Sowerby, in his comment on plate 257, _Eng. Fungi_, says: "It appears to consist of branching threads affixed to the deal and holding a dense mass of sooty powder. Over the whole is a thin, deciduous pellicle." This description seems to be applicable to nothing else. The figure amounts to little. Fries recognizes the English description, as does Rostafinski, but both authors adopt the later name given by Albertini and Schweinitz, simply because of the excellent detailed description found in the _Conspectus_.

2. AMAUROCHAETE TUBULINA (_Alb. & Schw._) _Macbr._

PLATE XX., 6 and 6 _a_.

1805. _Stemonitis tubulina_ (Alb. & Schw.), _Cons. Fung._, p. 102. 1825. _Lachnobolus cribrosus_ Fr., _Syst. Orb. Veg._, p. 14. 1912. _Amaurochaete cribrosa_ (Fr.) Macbr., _Com. in litt._ to Herbaria, Harvard, etc.[35] 1917. _Amaurochaete cribrosa_ (Fr.) Sturg., G. Lister, _Jour. Bot._, LVIII, p. 109.

Plasmodium at first transparent then white then rosy, ashen or grey finally deepening to jet-black; the aethalium even, thin, variable in extent from one to ten centimeters, covered by a distinct but thin transparent cortex, papillate, extended laterally but a short distance beyond the fructification, fragile, soon disappearing; hypothallus long-persistent, thin, silvery, supporting the capillitium as if by stipes, short slender columns, irregular plates, expansions, etc.; the capillitium an intricate network, very abundant, elastic, on fall of the peridium appearing like tiny tufts of wool, the meshes large, but formed as in _Stemonitis_, persistent, dull black; spores, under the lens, dull olivaceous black, minutely roughened, 12-14 mu.

This species differs from the preceding, already well known, especially in the capillitial characters. In the older species the capillitial branches fray out, and are only sparingly united into a net extremely lax. In the present form the net is the thing, common to all sporangia. The total effect is to lend to the blown-out aethalium a woolly appearance, entirely unlike that of its congener under the same conditions. But until fructification is quite mature, the presence of the collaborating sporangia below is indicated, suggested, by the papillose upper surface.

The amaurochetes are remarkable in that they appear upon coniferous wood, logs or lumber, to all appearance undecayed. The species just described developed abundantly in August on the recently decorticated logs of _Pinus ponderosa_, on the south-western slopes of Mt. Rainier, Washington. In logging operations in the locality referred to, the trees are felled often at considerable distance from the mill. They are not infrequently large, 75-120 cm. in diameter. The logs are dragged along the ground, the transportation facilitated by removal of the bark from the new fallen trunk. In a few weeks' time, affected by alternate rain and sun, the whole surface becomes marked with hundreds of minute, almost invisible cracks, and it is in the larger of these that the plasmodium of the present species has its habitat. Hardly any mycologic phenomenon is more surprising than to see plasmodia rising to fructification, scores at a time, upon a surface, new and white, showing otherwise no evidence of any decomposition. Doubtless the persisting cambium, the unused starches, sugars, the wood of the season yet unlignified, afford easily accessible nutrition.

When this form was first examined in the laboratory its distinctness was immediately seen. It was without doubt Fries' cribrose reticularia; nobody questions that. Under this name, citing Fries' description, specimens were sent out to herbaria as Harvard. Further study of the records, however, soon convinces one familiar with the ontogeny of the case that we are here face to face with the species, described by Alb. & Schw. in their fine _Conspectus_. Their account of the form, evidently often taken and now described with great care, is entirely clear when read in presence of the facts. It is here submitted, as less easy of access but essential, if the reader would appreciate the present disposal of the species.

"S. Tubulina NOBIS

"_S. magna pulvinata subhemisphaerica, stylidiis gregariis circinantibus, capillitiis elongatis cylindraceis in massam pulveraceam fuscam connatis, apicibus obtusis, prominulis, lucidis nigris._

"The size indeed, the circumscribed form, the capillitiums conjoined into a single body--indue this (form) with an appearance peculiar to a degree; however, should anyone prefer to call it a very remarkable variety of the preceding (_S. fasciculata_), we shall not strenuously refuse. At first glance it looks like a tubulina. After the fashion of its kind, the beginning is soft and milky. The diameter generally an inch and a half to two inches, the height four to six lines; the form perfectly round, or more rarely somewhat oblong. The hypothallus, stout, pellucid silvery, betimes iridescent, when turned to the light, easily separable from the substratum, bears the columellae, dusky, thin, hair-like, aggregate and yet entirely free, and everywhere circinately convergent, depressed by the superimposed burden, hence decumbent: ... the capillitium loosely interwoven, coalesces to a common mass whose smooth and shining surface shows above, regularly disposed minute papillae, the apices of individual sporangia.

"Far from infrequent, on decorticate pine, of _Lycogala atrum_ a constant companion"!

It goes of course without saying, that for the authors quoted, _Lycogala atrum_ is _Amaurochaete atra_ Rost. _A. fuliginosa_ (Sow.) of more recent students, described and perfectly figured in the volume cited.

It is surprising that they did not enter the present species also as a lycogala. But the stemonitis relationship this time impressed them rather than the aethalial; besides they were misled by the _S. fasciculata_ of Gmelin and Persoon, a composite which the genius of Fries hardly availed to disentangle twenty-five years later.

The last named author, as we see, wrote first _Lachnobolus_, then _Reticularia_. He calls the interwoven capillitium--_lachne_, wool, a "_pilam tactu eximie elasticam_," etc. He read the description in the _Conspectus_, but carried away the stemonitis suggestion dominant there, as we have seen, put _S. tubulina_ A. & S. as an undeveloped phase of _S. fusca_, which, of course, it is not. It needed not the authority of Rostafinski, _Mon._, p. 197, to assure us this. The earlier authors describe the species in course of development to complete maturity, and clinch the story by declaring the form a constant companion of the commonly recognized amaurochete, so fixing the relationship for us by habitat also.

These men made a mistake, of course, in placing their species among the stemonites at all. They did much better however than Fries who called it a reticularia. It was also a mistake to cite _S. fasciculata_,--the small fasciculate tufts of _S. fusca_ and _S. axifera_ offering by the aggregate habit only faint resemblance,--a possible refuge for those who would prefer another disposition of their species distinct (_aliena_) though it is.

Since Fries' day the species has been overlooked although the genus has received more than once attention. Zukal _Hedwigia_, XXXV., p. 335, describes _A. speciosa_ as a new species. This Saccardo writes down, Syll. Fung., VII., p. 399, _S. tubulina_ A. & S., admitting, however, at the same time, that as fine an authority as Raciborsky refuses to call Zukal's species either a stemonite or an amaurochete, thinks it deserving generic appellation of its own.

However, _A. speciosa_ Zuk. need not here concern us. Neither in his description nor figures does Zukal at all approach the form we study. His species is not an amaurochete; the size of the spores suggest that, to say nothing of the capillitial structure.

In the same volume VII., the distinguished author introduces another amaurochete, _A. minor_ Sacc. & Ellis, _Mich._ II., p. 566. This is American; sent from Utah by our famous pioneer collector Harkness. A specimen is before us: it is a lepidoderma! in shining, scaly armor dressed; vid. under _L. carestianum_.

Since the distribution of Washington material, as mentioned, our species reappears at various points in western Europe, points in England, etc., and will no doubt now share, hereafter as a century ago, the habitat so long conceded to the long familiar older type.

_B._ STEMONITACEAE

Capillitium abundant, springing usually as dissipating branches from all parts of the columella; the sporangia generally definite and distinct, though sometimes closely placed and generally rising from a common hypothallus.

=Key to the Genera of the Stemonitaceae=

_A._ Fructification aethalioid; capillitium charged with vesicles 1. _Brefeldia_

_B._ Sporangia distinct, or nearly so.

_a._ Stipe and columella jet-black.

1. Capillitium so united as to form a surface net 2. _Stemonitis_

2. Capillitial branch-tips free 3. _Comatricha_

_b._ Stipe and columella whitish; calcareous 4. _Diachaea_

=1. Brefeldia= _Rostafinski_

1873. _Brefeldia_ Rost., _Versuch_, p. 8.

Sporangia occupying in the aethalium several layers, those of the median, and especially of the lowest layers, furnished with columellae which blend beneath; capillitium threads in the lowest layers arising from the columella, in the upper extending radiately between the individual sporangia, and united at the sporangial limits by means of rather large inflated sacs.

The genus _Brefeldia_ is, like some others, difficult to dispose of in any scheme of classification where linear sequence must be followed. Rostafinski placed it in an order by itself. Its relationships are on the one hand with _Amaurochaete_ and _Reticularia_, and on the other with the _Stemonitales_, though easily distinguished from either. It is intermediate to _Amaurochaete_ and _Stemonitis_, and withal, as it appears to us, a little nearer the latter, as the limits of the individual sporangia are in _Brefeldia_ pretty well defined.

1. BREFELDIA MAXIMA (_Fr._) _Rost._

PLATE V., Figs. 7, 7 _a_, 7 _b_, and PLATES XXI., XXII.

1825. _Reticularia maxima_ Fries, _Syst. Orb. Veg._, I., p. 147. 1875. _Brefeldia maxima_ (Fr.) Rost., _Versuch._, p. 8.

Aethalium large, four to twenty cm, papillate above, violet-black at first, then purple or purple-brown, developed upon a widespread, silver-shining hypothallus; sporangia in favorable cases distinct, indicated above by the papillae; columellae obscure, black; capillitium abundant, the threads uniting by multifid ends to surround as with a net the peculiar vesicles; spore-mass dark violet-black, the individual spores paler by transmitted light, distinctly papillose, 12-15 mu.

A very remarkable species and one of the largest, rivalled by _Fuligo_ only. To be compared with _Reticularia_, which it resembles somewhat externally, and with some of the larger specimens of _Enteridium_. The plasmodium at first white with a bluish tinge is developed abundantly in rotten wood, preferably a large oak stump, and changes color as maturity comes on, much in the fashion of _Stemonitis splendens_, leaving a widespread hypothallic film to extend far around the perfected fruit-mass. In well-matured aethalia, "_Jove favente_," the sporangia stand out perfectly distinct, particularly above and around the margins. Closely and compactly crowded, they become prismatic by mutual pressure, and attain sometimes the height of half an inch or more. In the centre of the fructification, next the hypothallus, the sporangia are very imperfectly differentiated. Many are here horizontally placed, and perhaps supplied with an imperfectly formed peridium,--if so are to be interpreted the lowest parts of the capillitial structure, the long, branching, ribbon-like strands which lie along the hypothallus. Some of these branch repeatedly with flat anastomosing branchlets, ultimately fray out into lengthened threads, and perish after all the superstructure has been blown away. From every part of the structure so described, but more especially from the margins, are given off in profusion the strange cystiferous threads, so characteristic of this genus. These are exceeding delicate filaments, attached at one end, it may be, to a principal branch, at the other free or united to a second which again joins a third, and so looping and branching, dividing, they form a more or less extended network, a capillitium in which are entangled the myriad spores. Each filament bears at its middle point (or is it the meeting point of two?) a peculiar plexus which embraces several large cysts or vesicles whose function or further homology does not readily appear.

From the base of the fructification rise also ascending branches which are black, terete, and not infrequently branched as if to form the capillitium of a stemonitis. These ascending branches are in many cases, probably in all, real, though as yet imperfectly developed, columellae. They rise, at least in many cases, directly from the hypothallus, each is central to an individual sporangium, rises to about two-thirds its height, but never attains the summit. The sporangia are so crowded that many are choked off below, never reach the top of the aethalium. In such cases the columella may cease at the sporangium-top. The columella bears cystiferous threads sparingly, if at all; nevertheless these abound in the peripheral portions of the sporangium all the way up, and are especially noticeable beyond the level of the top of the columella. Many are so arranged that the plexus with its vesicles occupies a place in the plane separating adjacent sporangia, suggesting the possibility that we have here to do with an imperfectly developed surface-net and peridium. In this view the cysts would represent the meeting-point of two opposite radial capillitial threads rather than the middle of one. This accords with Rostafinski's observations and drawings. The cysts, then, belong morphologically to the peridium or sporangium wall. It is a stemonitis whose sporangia have never been perfectly differentiated, a case of arrested development. See further under _Stemonitis confluens_.

Rostafinski really offers the first definitive description. Fries probably distinguished it, but his description would not indicate the fact except for the added note wherein appears the reason for discarding an apparently older name, viz., that given by Link. But neither Link nor Sowerby distinguished by description or figure _Brefeldia_ from _Amaurochaete_.

Throughout the northern forest; Maine to Vancouver Island: not common.

=2. Stemonitis= (_Gleditsch_) _Rost._

1753. _Stemonitis_ Gleditsch, in part, _Meth. Fung._, p. 140. 1873. _Stemonitis_ (Gleditsch) Rost., _Versuch_, p. 7.

Sporangia distinct, though often closely aggregate, cylindric, stipitate; columella prominent; capillitium well developed by repeated lateral and apical branching of the columella, at length assuming at the surface the form of a distinct net which supports an evanescent peridium.

The genus is marked by its surface-net supported at the tips of the dichotomously branched divisions of the columella. Over the net is spread, theoretically at least, the peridial film supported by very short points projecting from the net,--the peridial processes; the peridium, however, is seldom seen; in some cases, certainly, is never developed. Rostafinski first defined the genus as employed by recent writers. Gleditsch simply renamed Micheli's _Clathroidastrum_; all writers subsequent included species of other genera.

The taxonomy of this genus is of the most difficult. Macroscopic, defining characters are few, and even these sometimes uncertain. Microscopic distinctions also tend to be illusive, variable in such fashion that often at the critical point the most exact description fails. All that may be done at present is to recognize two or three definite types and then cautiously differentiate among these with the light we have, until more general study of the group brings to service a wider range of observation with more comprehensive record on which judgment may better be sustained.

We have before us many and beautiful forms of this genus yet unstudied. Some of these doubtless have already found place in our growing taxonomic literature; some apparently undescribed; all to wait wider leisure or perhaps a younger hand.

The entire life-history of every form is none too much if we would set out with any hope of accuracy the genetic relationships for which taxonomy stands. Recently European students are making the color of the plasmodium a basis for species-discrimination, which is good so far. But plasmodic characters are at present unserviceable generally, for two reasons; they vary in the same species; and unfortunately, when most needed, they are unknown and inaccessible. The student is generally confronted by forms mature, the plasmodic stage already past.

=Key to the Species of Stemonitis=

_A._ Sporangia connately united.

_a._ Spores verruculose 1. _S. confluens_

_b._ Spores reticulate 2. _S. trechispora_

_B._ Sporangia at maturity distinct.

_a._ Spore-mass grayish black.

1. Larger, 8-12 mm. spores distinctly reticulate or warted, but sometimes nearly smooth 3. _S. fusca_

2. Spores reticulate and spinulose.

i. Spores adherent, clustered 4. _S. uvifera_

ii. Sporangia very tall, 15-20 mm., rigid 5. _S. dictyospora_