Chapter VIII: Section 2: =Tilmadoche= Fries (1)

53. PHYSARUM GYROSUM (_Rost._) _Jahn._

1875. _Physarum gyrosum_ Rost., _Mon._, p. 111.
1902. _Physarum gyrosum_ Rost., Jahn, _Ber. Deutsch. Bot. Ges._, XX.,
p. 272, t. XIII.
1911. _Physarum gyrosum_ Rost., List., _Mycetozoa, 2nd ed._, p. 75.

Sporangia gyrose, variable in form, or plasmodiocarpous and irregular, venulose, sessile upon a common, strongly developed hypothallus, sometimes isolated and irregularly globose, dehiscing irregularly or by longitudinal fissure, yellowish or greyish white; columella none; capillitium delicate, the nodules elongate, variable in size; spores pale violaceous, minutely spinulose, 7-10 mu.

This is a European species recently resuscitated by Dr. Jahn. It perhaps might more correctly be recorded as _P. gyrosum_ Jahn, since Rostafinski certainly attempted in his description to cover two apparently distinct things. He seems to have had before him _Fuligo muscorum_ Schw. and "_P. gyrosum_," but he thought them the same, and his description touches now one, now the other. Since _F. muscorum_ Schw. has all along held its own and received due recognition, it is interesting to note the recovery of this gyrose form.

Judging by description and figures, it resembles a very large, sessile phase of _P. polycephalum_. See further under that species.

Europe, Japan, Eastern United States (?).

54. PHYSARUM POLYCEPHALUM _Schw._

PLATE VIII., Figs. 2, 2 _a_, 2 _b_.

1822. _Physarum polycephalum_ Schw., _Syn. Fung. Car._, No. 382.
1829. _Didymium polycephalum_ (Schw.) Fries, _Syst. Myc._, III.,
p. 122.
1837. _Didymium polymorphum_ Mont., _Ann. Sci. Nat._, Ser. 2, 8,
p. 361.
1837. _Didymium gyrocephalum_ Mont., _op. cit._, p. 362.
1875. _Physarum polymorphum_ (Mont.) Rost., _Mon._, p. 107.
1875. _Tilmadoche gyrocephala_ (Mont.) Rost., _Mon._, p. 131.
1899. _Tilmadoche polycephala_ (Schw.) Macbr., _N. A. S._, p. 57.
1911. _Physarum polycephalum_ Schw., List., _Mycetozoa, 2nd ed._,
p. 58.

Sporangia spherical or irregular, impressed, gyrose-confluent, helvelloid, umbilicate below; peridium thin, ashy, covered with evanescent yellow squamules, fragile; stipe from an expanded membranaceous base, long-subulate, yellow; spores smooth, violet, 9-11 mu.

A most singular species and well defined is this, occurring in masses of decaying leaves or on rotten logs. The plasmodium at first colorless; as it emerges for fructification, white, then yellow, spreading far over all adjacent objects, not sparing the leaves and flowers of living plants; at evening slime, spreading, streaming, changing; by morning fruit, a thousand stalked sporangia with their strangely convoluted sculpture. The evening winds again bear off the sooty spores, and naught remains but twisted yellow stems crowned with a pencil of tufted silken hairs. August.

Although Rostafinski's description of this species is accurate and marks exactly a _Tilmadoche_ and is very different from his description of _Physarum polymorphum_, nevertheless it is probable that both descriptions have reference to the same thing. All specimens on which both species were based were American; _P. polymorphum_, North American. But the only North American form to which reference can be made is that by Schweinitz called _P. polycephalum_ and, fortunately, sufficiently described. Furthermore, Rostafinski, under _T. gyrocephala_, himself affirms the probable identity of Montagne's _Didymium gyrocephalum_ with the Schweinitzian species, and uses Montagne's specific name provisionally. For these reasons it seems proper to write the species as above.

Widely distributed and common, from Maine and Canada to Nebraska, and Washington and south to Nicaragua.

This species is so common that its plasmodium and fructification may be easily observed. Professor Morton E. Peck, who has been for years a close observer of the vegetative phases of our Iowa species, says of _P. polycephalum_: "In one instance I observed a plasmodium for twelve successive days on the surface of a decaying stump. During this period it crept all around the stump and from top to bottom several times. At one time the color was bright yellow; at another, greenish yellow; and once, shortly before fruiting, it became clear bright green. A heavy rain fell upon the plasmodium but it appeared to sustain little injury and ultimately developed normal sporangia."

55. PHYSARUM NUTANS _Pers._

1791. _Sphaerocarpus albus_ Bull., _Champ._, p. 137, t. 407, III.,
and t. 470, I, A-L.
1791. _Stemonitis alba_ (Bull.), Gmel., _Syst. Nat._, p. 1469 (?).
1795. _Physarum nutans_ Pers., _Ust. Ann. Bot._, XV., p. 6.
1803. _Trichia cernua Schum., Enum. Pl, Saell._, II., p. 241.
1829. _Physarum cernuum_ (Schum.) in part, Fr., _Syst. Myc._, III.,
pp. 130, 147.
1848. _Tilmadoche cernua_ (Schum.) Fr., _Summ. Veg. Sc._, p. 454.
1873. _Tilmadoche nutans_ (Pers.) Rost., _Versuch_, p. 10.
1899. _Tilmadoche alba_ (Bull.) Macbr., _N. A. S._, p. 58.
1911. _Physarum nutans_ Pers., List., _Mycet., 2nd ed._, p. 67,
in part.

Sporangia gregarious, depressed-spherical, stipitate, umbilicate, gray or white, thin-walled, nodding; stipe long, tapering upward, brown or black below, ashen white above, lightly striate, graceful; capillitium abundant, threads delicate, intricately combined in loose persistent network with occasional minute, rounded, or elongate calcareous nodules; spores minutely roughened, globose, about 10 mu.

The nodding, lenticular, umbilicate sporangium, barely attached to the apiculate stipe, is sufficient to distinguish this elegant little species, recognized and quite aptly characterized by mycologists for more than one hundred years. As _Sphaerocarpus albus_ Bulliard first prescribed the limits by which the species is at present bounded. The description by Fries (_Syst. Myc.,_, III., 128) is especially graphic; "Peridium very thin, in form quite constantly lenticular, umbilicate at base, at first smooth then uneven, generally laciniate-dehiscent, the segments persistent at least at base."

The stipe is usually white above, fuscous below, at the apex almost evanescent; hence the cernuous sporangia. The same character is less strikingly manifest in the species next following.

The plasmodium is bright yellow, sometimes greenish. Brought in from the field and maturing under a bell-jar, the color changes to a watery white just before the sporangia rise in fruit. _P. album_ Fuckel, _Rhen. Fl._, No. 1469, 1865, is believed to be _P. cinereum_ (Batsch) Pers.

Persoon changed Bulliard's specific name in this case to furnish one himself, more descriptive as he thought and distinctive. His success in this attempt must be esteemed but partial since all the related forms, immediately listed, _nod_ as well. Bulliard's name as applied by Persoon is therefore to be preferred. But the transfer from _Tilmadoche_ to _Physarum_ loses for us one step in the ladder of priority. _P. album_ (Bull.) may not enter here, since Fries has given us one species under that title. So Persoon comes next on the list, all the world now nodding approbation, let us hope!

Under the name _Physarum gracilentum_, Fries cites an extremely delicate form of this species. The sporangia are of the most minute, about .2-.3 mm. in diameter, globose, slightly umbilicate below, the stipe usually white at top, but sometimes black throughout. This graceful form occurs rarely in undisturbed woods.

Widely distributed in the eastern United States, apparently rare in the west. Reported from various parts of the world; Europe, Japan, Australia, etc.

56. PHYSARUM VIRIDE (_Bull._) _Pers._

PLATE VIII, Figs. 8, 8 _a_, 8 _b_.

1791. _Sphaerocarpus viridis_ Bull., _Champ._, t. 407, Fig. I.
1791. _Sphaerocarpus luteus_ Bull., _Champ._, t. 407, Fig. II.
1791. _Sphaerocarpus aurantius_ Bull., _Champ._, t. 484, Fig. II.
1791. _Stemonitis viridis_ (Bull.) Gmel., _Sys. Nat._, p. 1469.
1794. _Physarum aureum_ Pers., Roemer, _Neu. Mag. f. die Bot._, I.,
p. 88.
1795. _Physarum viride_ Pers., Usteri, _Ann. Bot._, XV., p. 6.
1801. _Physarum aurantium_ Pers., _Syn. Meth._, p. 173.
1829. _Physarum nutans_ var. Fries, _Syst. Myc._, III., pp. 128-129.
1875. _Tilmadoche mutabilis_ Rost., _Mon._, p. 129.
1880. _Tilmadoche viridis_ (Bull.) Sacc., _Michelia_, II., p. 263.
1894. _Physarum viride_ Pers., List., _Mycetozoa_, p. 50.
1899. _Tilmadoche viridis_ (Bull.) Sacc., Macbr., _N. A. S._, p. 59.
1911. _Physarum viride_ Pers., List., _Mycetozoa_, 2nd ed.

Sporangia globose, flattened or lenticular, beneath plane or concave, variously colored, yellow, greenish yellow, rusty orange, stipitate, nodding; the peridium splitting irregularly or reticulately; stipe variable in length and color, through various shades of red and yellow, subulate; capillitium strongly developed, concolorous with sporangium, the tubes with colorless or yellow calcareous thickenings; spores smooth, fuscous or violet-black, 8 mu.

A very handsome and rather common little species; like the preceding, but generally greenish-yellow in color, and occasionally brilliantly orange without a suggestion of green. Indeed, the color is so variable that some authors have been disposed to discard the species entirely, inasmuch as the chief specific character is color. The plasmodium is pale yellow, in rotten logs, stumps, etc. In the paler yellow or greenish forms the stipe is more commonly black.

This is _Physarum luteum_ (Bull.) Fries, and likewise also includes the three varieties, _viride_, _aureum_, _coccineum_, listed by the same author under _P. nutans_, while he at the same time remarks that they might with equal propriety be elsewhere referred. Rostafinski considers that all the colored forms agree in capillitium sufficiently to be associated under one name and are in the same way unlike _T. nutans_.[29] Rostafinski thinks to avoid confusion by suggesting a more fitting specific name, _T. mutabilis_, but there seems no good reason for not adopting the earliest identifiable specific appellation, which in this case appears to be _viride_. The yellow phase is common in Iowa, resembles in size, color, stipe, _P. galbeum_ Wingate, but is instantly distinguishable by the capillitium. _N. A. F._, 1213.

Widely distributed specimens are before us;--from New England, New York, Pennsylvania, Maryland, Ohio, Nebraska, Iowa, California, Oregon, Canada, Nicaragua, Samoa, Alaska, India, etc.

=EXTRA-LIMITAL=[30]

PHYSARUM MUTABILE (_Rost._) _List._

1875. _Crateriachea mutabilis_ Rost., _Mon._, p. 125.
1892. _Crateriachea mutabilis_ Rost., Mass., _Mon._, p. 344.
1894. _Physarum cinereum_ List., _Mycetozoa_, p. 55, in part.
1895. _Physarum crateriachea_ List., _Jour. Bot._, XXXIII., p. 323.
1910. _Physarum crateriachea_ List., Petch, _Mycetozoa Ceylon_,
p. 336.
1911. _Physarum mutabile_ List., _Mycetozoa, 2nd ed._, p. 53.

Sporangia cylindrical ovoid or sub-globose white, plasmodiocarpous, sessile or stipitate, stipes when present yellow, with or without lime, often connected by a hypothallus; peridium thin, squamulose; capillitium persistent, intricate, the nodules white, more or less confluent at the center to form a real or a pseudo-columella; spores brownish-purple, spinulose, 7-8 mu.

Reported from Europe, Africa, Ceylon.

PHYSARUM ROSEUM _Berk. & Br._

1873. _Physarum roseum_ Berk. & Br., _Jour. Linn. Soc._, XIV., p. 84.

Plasmodium rose-red; sporangia gregarious, stipitate, globose, rose-red; the stipe erect, brown, rugulose, translucent; capillitium lax, delicate, lilac, the nodules few, large, purple-red, branching; spores reddish-lilac or brown, minutely spinulose, 7-10 mu.

Reported from Ceylon, Java, Borneo, Japan.

PHYSARUM DICTYOSPERMUM _List._

1905. _Physarum dictyospermum_ List., _Jour. Bot._, Vol. XLIII.,
p. 112.

"It is distinguished from the other known species of _Physarum_ by the strongly reticulated spores. Its nearest ally is perhaps _P. psittacinum_ which it resembles in having orange-red lime-knots and in the sporangium-wall being studded with orange crystalline disks." _Lister._

Reported collected once only; New Zealand.

PHYSARUM STRAMINIPES _List._

1898. _Physarum straminipes_ List., _Jour. Bot._, Vol. XXXVI., p. 163.

Plasmodium white; sporangia greyish-white, obovoid or wedge-shaped, .7 mm. in diameter, clustered or scattered, stipitate or sessile, when stipitate stalks long, weak; peridium membranous, pale purple; capillitium a persistent rigid net, the nodules white, rounded, sometimes aggregate as a pseudo-columella; spores purple-brown, 10-11 mu, warted, the papillae in definite patches.

Related to _P. compressum_.

Reported from England; Germany.

PHYSARUM CRATERIFORME _Petch._

_Physarum crateriforme_ Petch, _Ann. Perad._, IV., p. 304.
_Physarum crateriforme_ Petch, List., _Mycetozoa, 2nd ed._, p. 69,
Pl. 76.

Sporangia gregarious, globose, clavate or crateriform, sessile or stipitate, white; stalk when present opaque conical, black below, white above, in crateriform sporangia entering and developed as a columella; capillitium various, strongly calcareous, the nodules either grouped in a pseudo-columella, or in globose sporangia, rod-like, ascending; spores closely spinulose, 11-15 mu.

Reported from Ceylon, Japan, West Indies; Lisbon.

PHYSARUM GULIELMAE _Penzig._

1898. _Physarum gulielmae_ Penzig., _Myx. Beut._, p. 34.
1909. _Physarum gulielmae_ Penzig., Torrend, _Fl. des Myx._, p. 208.
1911. _Physarum gulielmae_ Penzig., List., _Mycetozoa, 2nd ed._,
p. 76.

Plasmodium yellow; sporangia sub-globose, sessile, brownish-orange or chestnut brown, rugulose, clustered or heaped, often with a yellow membranous hypothallus; peridium membranous with clustered deposits of yellowish-brown lime granules; capillitium abundant, the nodes angular, branching, white; spores purplish brown, spinulose, 10-12 mu.

Reported from Java, Sweden, Switzerland.

PHYSARUM ECHINOSPORUM _List._

1899. _Physarum echinosporum_ List., _Jour. Bot._, XXXVII., p. 147.

This species is distinguished from the preceding chiefly in episporic characters. "Spores purple, 8 mu, marked by strong ridges and spines," 8 mu.

Reported from Antigua.

PHYSARUM AENEUM (_List._) _R. E. Fries._

1898. _Physarum murinum_ var. _aeneum_ Lister, _Jour. Bot._, XXXVI.,
p. 117.
1903. _Physarum aeneum_ Lister, R. E. Fries, _Arkiv. Bot._, I., p. 62.

Sporangia sessile, sub-globose or plasmodiocarpous, pinkish-brown or bronze, glossy; peridium double, the outer somewhat cartilaginous, brittle, falling back from the shining, membranous inner wall; capillitium dense, the nodules not large, brown, sometimes aggregated to form a pseudo-columella; spores pale brownish-violet, nearly smooth, 6-8 mu.

Reported from West Indies, Bolivia.

=Related Genus=

TRICHAMPHORA _Junghuhn_, p. 12.

1838. _Trichamphora_, Junghuhn, _Fl. Crypt. Javanica_.

Sporangia discoidal, above concave, saucer-shaped, stipitate; the capillitium variable, anon physaroid, badhamioid, or even as in _Didymium_.

This genus is set up for the accommodation thus far of the single species following. It differs from _Physarella_ in the apparently constant discoidal shape, absence of trabecules, etc.

TRICHAMPHORA PEZIZOIDEA _Jungh._, _op. cit._

1838. _Trichamphora pezizoidea_ Jungh., _op. cit._
1854. _Didymium zeylanicum_ Berk. & Br., _Hook. Jour. Bot._, VI.,
p. 230.
1869. _Physarum macrocarpum_ Fuckel, _Symb. Myc._, p. 343.
1875. _Chondrioderma pezizoidea_ Rost., _Mon._, p. 424, tab. VIII.,
Fig. 122.
1876. _Badhamia fuckeliana_ Rost., _Mon._, _App._, p. 2.
1894. _Trichamphora pezizoidea_ Jungh., List., _Mycetozoa_, p. 89.
1911. _Trichamphora pezizoidea_ Jungh., List., _Mycetozoa, 2nd ed._,
p. 90.

Sporangia discoidal or saucer-shaped, gregarious, stipitate, erect or nodding, grayish-white, the peridium thin, breaking irregularly and persistent; stipe subulate, striate, reddish brown, transparent; capillitium variable as above stated; spores pale violet-brown, spinulose or nearly smooth, about 9 mu.

In _Mycetozoa, 2nd ed._, the spores are described as "dark or pale purplish brown, spinose, spinulose or nearly smooth, 9-17 mu in diameter." This would seem too great a variation even in this protean species. The only specimens in our herbarium are from the Congo valley. The spores are pale and nearly smooth, as in _Tilmadoche alba_, and 9 mu. Spores 17 mu suggest immaturity; penultimate cell-division.

The synonymy above cited shows how this species has impressed careful students. Doubtless in every case the reference is correct, judging from the specimen each author had before him, although it is hard to see how _Chondrioderma_ might have been suggested.

The species is evidently tropical, though reported from Europe.

=4. Craterium= _Trentepohl_

1797. _Craterium_ Trentepohl, Roth, _Catal._, I., p. 224.

Sporangia more or less distinctly cyathiform, stipitate, the peridium generally plainly of two layers or even of three, opening at the top by circumscission more or less definite, or by a distinct lid, the upper part calcareous often to a marked degree, the lower, cartilaginous, long persistent as a vasiform cup containing the capillitium and spores, the calcareous nodes aggregating more or less to form a pseudo-columella.

This genus is distinguished from _Physarum_ and _Badhamia_ chiefly by the form of the sporangia and the method of dehiscence. The capillitium is in some specimens particularly, of the _Physarum_ type; in others, like that of _Badhamia_. There are accordingly species that receive at the hands of different authors diverse generic reference as one feature or another in the structure is emphasized in the different cases. It is granted that it is hard to draw the line sometimes between forms in which the dehiscence is irregularly circumscissile and those in which the wall breaks without any regularity whatever, since, in all, the breaking up of the peridium usually begins at the top. Species here included will, however, offer little ambiguity.

=Key to the Species of Craterium=

A. Dehiscence circumscissile or by the breaking up of the upper wall
of the sporangium.

_a._ Sporangia violet or purple 1. _C. paraguayense_

_b._ Sporangia yellow 2. _C. aureum_

_c._ Sporangia white-capped.

1. Sporangia obovoid or globoid 3. _C. leucocephalum_

2. Sporangia cylindric, elongate 4. _C. cylindricum_

B. Dehiscence by a distinct lid.

_a._ Capillitium pale brown 5. _C. concinnum_

_b._ Capillitium white 6. _C. minutum_

1. CRATERIUM PARAGUAYENSE (_Speg._) _List._

1883. _Didymium paraguayense_ Speg., _Fung. Guar. Pug._, 1, p. 141.
1893. _Craterium rubescens_ Rex, _Proc. Philad. Acad. Nat. Sci._,
p. 370.
1894. _Craterium rubescens_ Rex, List., _Mycetozoa_, p. 71.
1899. _Craterium rubescens_ Rex, Macbr., _N. A. S._, p. 75.
1904. _Iocraterium paraguayense_ (Speg.) Jahn, _Hedwigia_, XLII.,
p. 302.
1911. _Craterium paraguayense_ List., _Mycetozoa, 2nd ed._, p. 95.

Sporangia gregarious, cylindrical or elongate cyathiform, stipitate, dark violet-red, the apex slightly roughened by pale calcareous granules, the peridium longitudinally wrinkled below; dehiscence, irregularly circumscissile; stipe darker, one-half the height of the sporangium, longitudinally wrinkled; capillitium dense, abundantly calcareous; spores violet-brown, minutely roughened, 7-8 mu.

In form resembling the following species, but instantly distinguished by the color, which is red throughout, tinged with purple or violet. The capillitium is badhamioid, as noted by Dr. Rex. Very distinct from _P. newtoni_ in color, form, habit, epispore, etc.

2. CRATERIUM AUREUM (_Schum._) _Rost._

1803. _Trichia aurea_ Schum., _Enum. Pl. Saell._, II., p. 207.
1829. _Craterium mutabile_ Fries, _Syst. Myc._, III., p. 154.
1875. _Craterium aureum_ (Schum.) Rost., _Mon._, p. 125.

Sporangia gregarious, globose or obovoid, stipitate, yellow, erect, the peridial wall thin, especially at the summit, where at maturity it breaks up somewhat reticulately, leaving the persistent lower portion with an uneven margin above which projects the pale yellow capillitium; stipe short, orange, or brownish-red, arising from a small hypothallus; capillitium dense, yellow, the nodules not large, irregular, tending to form a pseudo-columella in the centre of the cup; spores minutely warted, violaceous-brown, 8-10 mu.

Fries regards this, which he names _C. mutabile_, the most distinctly marked species of the genus; chiefly, as it appears, on account of the bright yellow color. This, however, varies. Some specimens before us are gray, showing only a trace of yellow below. In some European specimens a reddish tinge prevails. The form of the sporangium also varies. In typical specimens, unopened, the shape is almost pyriform; opened, we have a cylindric, oftenest lemon-yellow vase, mounted on a short striate stalk. But again, from the same plasmodium, we may have globose sporangia, opening so as to leave only a shallow, salver-shaped base. In this case the stipe is also longer. The plasmodium is said to be "clear lemon yellow."--_Massee._

There seems little doubt that Schumacher had in mind the present species in his _Trichia aurea_. Rostafinski shows that Fries's synonym, _C. mutabile_, is founded on a mistake. The earlier specific name is therefore on Rostafinski's authority adopted.

Not common. Pennsylvania, New Jersey, North Carolina, Ohio, Iowa.

3. CRATERIUM LEUCOCEPHALUM (_Pers._) _Ditmar_.

PLATE VIII., Fig. 5.

1791. _Stemonitis leucocephala_ Gmelin, _Syst. Nat._, II., p. 1467.
1801. _Arcyria_ (?) _leucocephala_ Persoon, _Syn. Fung._, p. 183.
1801. _Craterium_ (?) _leucocephalum_, Persoon, _Syn. Fung._, p. 184.
1813. _Craterium leucocephalum_ (Pers.) Ditmar, Sturm, _Deutsch.
Flora, Pilze_, p. 21, Pl. 11.
1889. _Physarum scyphoides_ Cke. & Balf., _Jour. Myc._, V., p. 186.
1896. _Craterium convivale_ (Batsch) Morg., _Jour. Cin. Soc._, p. 86.

Sporangia gregarious, short-cylindric or ovate, pure white above, brown or reddish-brown below, stipitate, dehiscence irregularly circumscissile, the persistent portion of the peridium beaker-shaped; stipe short, stout, expanded above into the base of the peridium with which it is concolorous; hypothallus scant; capillitium white or sometimes, toward the centre, brownish, the calcareous nodules large, conspicuous, and persistent; spore-mass black, spores violaceous-brown, minutely spinulose, 8-9 mu.

Distinguished by its white cap from all except the next, from which the markedly different form serves as the diagnostic feature. In some gatherings, curious patches of yellow mark the otherwise snow white cap and sides; these are mere stains, or sometimes definite, crystalline, flake-like bodies, standing out in plain relief on the sporangial wall, or lurking in the larger nodules which are massed along the axis of the cup to form the pseudo-columella here strongly developed. Mr. Lister calls attention to these yellow flakes, and regards them as diagnostic. European specimens show the capillitium yellow, sometimes throughout!

The nomenclature question is here somewhat difficult. Fries heads his list of synonyms with _Peziza convivalis_ Batsch. Batsch simply described Micheli's figure! Now there is nothing in Micheli's figure (Pl. 86, Fig. 14) to enable one to say with certainty which craterium Micheli had in mind, if craterium at all. Nor does Batsch help the matter when he offers the description following: "Stipitata; acute conica, patens; stipite subdistincto, lineari, brevi, valido. _Albicans. In foliis hederae putridis._" (_Elenchus Fungorum_, Batsch, 1783, p. 121.) There is nothing definitive here but the one word "albicans" quoted from Micheli. But this term is applicable the rather to _C. minutum_, the cups of which whiten with weathering. It may be, as insisted by Fries (_Syst. Myc._, III., p. 149), that Micheli drew crateriums; but if so, we cannot determine which species.

The specific name here adopted was applied by Persoon probably to this form; but Persoon likewise failed to distinguish the present species from _C. minutum_ (see _Syn. Fung._, pp. 183, 184), and Fries, _op. cit._, p. 153. Ditmar, _l. c._, leaves no doubt as to what he figures and describes, and accordingly the name he first correctly uses is here adopted.

Not common. New England, Pennsylvania, Ohio, North Carolina, Iowa, Colorado, Washington, California; reported from Europe.

4. CRATERIUM CYLINDRICUM _Massee_.

PLATE XVI., Fig. 2.

1873. _Craterium minimum_ Berk. & C., _Grev._, II., p. 67.
1892. _Craterium cylindricum_ Massee, _Mon._, p. 268.
1894. _Craterium leucocephalum_ Ditm., List., _Myc._, p. 72, in part.
1899. _Craterium minimum_ Berk. & C., Macbr., _N. A. S._, p. 77.
1911. _Craterium leucocephalum_ var. _cylindricum_ List., _Mycetozoa,
2nd ed._, p. 97.

Sporangia closely gregarious, very small, .5 mu or less, slender, cylindric, almost entirely white, stipitate, the peridium delicate, transparent although calcareous nearly to the base, opening by a dehiscence regularly circumscissile; stipe short, about one-third the total height, clear orange-brown, somewhat furrowed, rising from an indistinct hypothallus; capillitium very lax, physaroid, the calcareous nodules large, rounded, pure white, aggregated at the centre of the cup; spore-mass black, spores minutely roughened, violaceous-brown, 8-9 mu.

This is the common form in the United States. Massee describes it as _C. cylindricum_ Mass., and it seems not to occur in Europe. Lister has put it in with _C. leucocephalum_, from which its more delicate structure and elegant cylindrical shape certainly distinguish it. The dehiscence is even more regular than in the preceding species and approaches that of _C. minutum_ Leers., with bleached forms of which it must not be confused. _N. A. F._, 1400.

_C. minimum_ Berk. & C. has here priority. Massee regards this name as indicating a distinct species. We have been unable to determine what the authors really had before them, and adopt accordingly the first available combination.

New England to Iowa and south; reported also from the orient.

5. CRATERIUM CONCINNUM _Rex._

1893. _Craterium concinnum_ Rex, _Proc. Phila. Acad._, p. 370.

Sporangia scattered, usually minute, broadly funnel-shaped, stipitate. The peridium simple, variously colored by innate lime granules, opening by a regular cap or operculum, brownish white, darkest in the centre, always more or less convex; stipe equalling the cup in height, dark brown, longitudinally ridged; the capillitium a close-meshed network, with small rounded or slightly angular masses of ochre-brown lime-granules, larger toward the centre; spores pale brown, minutely warted, 9-10 mu.

This species differs from the following, to which it seems most nearly allied, in form, color, as in the capillitium, and color of the spores. In habitat, however, it seems no less distinct, being found always (?) on the spines of decaying chestnut-burs lying on the ground, and in company with that other peculiar species _Lachnobolus globosus_.

The range is probably that of the chestnut, _Castanea dentata_ Borkhausen, east of the Mississippi River.

6. CRATERIUM MINUTUM (_Leers_) _Fr._

PLATE XV., Fig. 5.

1775. _Peziza minuta_ Leers, _Fl. Herborn_, p. 277.
1797. _Craterium pedunculatum_ Trent., Roth., _Catal. Bot._, I.,
p. 224.
1813. _Craterium vulgare_ Ditmar, Sturm, _Deutsch. Fl. Pilze_, p. 17.
1829. _Craterium pedunculatum_ Trent., Fr., _Syst. Myc._, III.,
p. 150.
1829. _Craterium minutum_ Leers, Fr., _Syst. Myc._, III., p. 151.
1893. _Craterium pedunculatum_ Trent., Macbr., _Bull. Lab. Nat. Hist.
Iowa_, II, p. 385.
1894. _Craterium pedunculatum_ Trent., Lister, _Mycetozoa_, p. 70.
1899. _Craterium minutum_ (Leers) Fr., Macbr., _N. A. S._, p. 78.
1911. _Craterium minutum_ Fr., List., _Mycetozoa, 2nd ed._, p. 94.

Sporangia scattered, gregarious, cyathiform or turbinate, grayish brown, stipitate, the peridial wall rather thick, double, opening by a distinct lid which lies usually below the slightly thickened and everted margin of the cup; stipe paler, translucent, about equalling in height the peridial cup, longitudinally wrinkled, with hypothallus scant or none; capillitium physaroid, the calcareous nodules large, white, and generally aggregated at the centre of the cup; spore-mass black, spores by transmitted light violaceous, minutely warted, 8-10 mu.

This is the most highly differentiated of the whole series. The cup is shapely and well defined, while the lid is not only distinct, but is a thin, delicate membrane of slightly different structure when compared with the peridial wall. It is in all the specimens before us much depressed below the mouth of the sporangium, and the whole structure in our specimens corresponds with Fries' description of _C. pedunculatum_ Trent., while specimens received from Europe correspond to Fries' account of _C. minutum_ Leers. Nevertheless we are assured that the two forms are in Europe developed from the same plasmodium, and therefore adopt the earlier specific name as above. _N. A. F._, 2500. This is probably _Fungoides convivalis_ of Batsch and Micheli.

In this species yellow sporangia are sometimes seen. Miss Currie reports from Toronto such variation and in Europe the case seems not unusual.

In fact, there is a yellow tinge about the sporangia of every species listed here, except the first. With the same exception, the plasmodium in every case is yellow.

Common throughout the eastern United States, west to Iowa, Colorado, and south to Louisiana; cosmopolitan.

=5. Physarella= _Peck._

1882. _Physarella_ Peck, _Bull. Torr. Bot. Club_, IX., p. 61.

Sporangium pervious to the base, the interior walls forming a persistent spurious columella; capillitium composed of filaments with here and there minute knot-like thickenings, straight tubes containing lime-granules extending from the exterior to the interior walls of the sporangium, persistently attached to the former.[31]

Such is Dr. Peck's original description of this most peculiar genus. The form of the sporangium in the only species is very variable, but in typical cases is vasiform, the peridial wall at the apex introverted. The capillitium is like that of _Tilmadoche_, except for the presence of the "straight tubes" emphasized in the original description. These are very remarkable and at once diagnostic. They take origin in the sporangial wall and pass across to the "columella"; but at the dehiscence of the sporangium, in typical cases, they remain attached at the points of origin, projecting as stout spine-like processes.

PHYSARELLA OBLONGA (_Berk. & C._) _Morg._

PLATE VIII., Figs. 4, 4 _a_, 4 _b_, 4 _c_; PLATE XVI., Figs. 1, 1 _a_, 1 _b_, and 6.

1873. _Trichamphora oblonga_ Berk. & C., _Grev._, II., p. 66.
1876. _Tilmadoche oblonga_ (Berk. & C.) Rost., _Mon. App._, p. 13.
1876. _Tilmadoche hians_ Rost., _Mon. App._, p 14.
1882. _Physarella mirabilis_ Peck, _Bull. Torr. Bot. Club_, IX.,
p. 61.
1893. _Physarella oblonga_ (Berk. & C.) Morg., _Jour. Cin. Soc._,
p. 79.
1894. _Physarella mirabilis_ Peck, List., _Mycet._, p. 68.
1899. _Physarella oblonga_ (Berk. & C.) Morg., Macbr., _N. A. S._,
p. 71.
1911. _Physarella oblonga_ Morg., List., _Mycet., 2nd ed._, p. 91.

Sporangia scattered or gregarious, typically cup-shaped or sub-infundibuliform, stipitate, erect or cernuous, but varying through low salver-shaped cups, to irregular applanate and sessile masses, the peridium thin but firm, tawny, roughened by numerous yellowish calcareous scales, at length ruptured above and often reflexed in the form of petal-like segments from which project upwards the spiniform trabecules of the capillitium; stipe when present long, terete, red, arising from a scant hypothallus and extended within the sporangium to meet the tubular "columella"; capillitium of delicate violaceous threads seldom branched or united, radiating from the columella with few calcareous nodular expansions, but supported by stout yellow calcareous trabecules, running parallel to the capillitial threads, long adherent to the sporangial wall; spores smooth, globose violet-brown, 7-8 mu.

Not uncommon in wet places. New York, Ohio, Iowa, South Dakota, Louisiana, Nicaragua; reported also from Ceylon, Java, etc.

Not the least remarkable feature of this remarkable species is the variation in the form of the fruit or sporangia. We have specimens from Louisiana (Rev. Langlois) which show no trace of columella, the whole structure involute and plicate, short stipitate, recalling the extremest complexity of such a species as _P. polycephalum_. _Vid._ Pl. XVI., Fig. 6. Moreover, in these specimens the calcareous deposits are white and not yellow, giving the entire fructification a grayish aspect. Yet there is no doubt we have here simply an exaggerated abnormality of the species; the spores are identical in size, color, and surface. Plasmodium bright yellow. Dr. Peck gave to his forms the name _Physarella mirabilis_; but specimens sent by Michener of Pennsylvania, and by Berkeley and Curtis described as _Trichamphora oblonga_ (_Grev._, II., p. 66), are the same thing. _N. A. F._, 1212.

_Physarella lusitanica_ Torrend is a globose form depressed above or betimes discoidal, occurring on Eucalyptus trees in Portugal. _P. oblonga_ is so variable in form that it sometimes suggests a different genus. Forms of it have been mistaken for _Fuligo gyrosa_ R., etc. Professor Torrend would include here _Physarum javanicum_ (Rac.), i. e. _Tilmadoche javanica_ as Raciborski saw it! We may not too often reflect that genera are purely artificial things set up for our convenience; but surely _Physarella_ as a natural genus is distinct enough to all.

=6. Cienkowskia= _Rost._

1873. _Cienkowskia_ Rost., _Versuch_, p. 9.

Fructification plasmodiocarpous, irregularly dehiscent, the wall a thin cartilaginous membrane destitute of lime, except the capillitial attachments within; capillitium scanty but rigid, and characterized everywhere by peculiar hook-like branchlets, free and sharp-pointed, the spores as in _Physarum_, etc.

The genus contains, so far, but a single species:--

CIENKOWSKIA RETICULATA (_Alb. & Schw._) _Rost._

PLATE XIV., Figs. 2, 2 _a_, 2 _b_.

1805. _Physarum reticulatum_ Alb. & Schw., _Cons. Fung._, p. 90.
1829. _Diderma reticulatum_ Fr., _Syst. Myc._, III., p. 112.
1873. _Cienkowskia reticulata_ (Alb. & Schw.) Rost., _Versuch_, p. 9.

Plasmodiocarp an elongated, irregularly limited, close-meshed net, closely applied to the substratum, the wall thin, transversely rugulose, and roughened, dull orange-yellow, splashed here and there with scarlet, anon entirely red, within marked by transverse calcareous ridges, supporting in part the calcareous system of the capillitium; capillitium of delicate, rigid, reticulating yellow tubules or threads with numerous free, uncinate or sickle-shaped branchlets, and large, irregular, calcareous plates, more or less transverse to the axis of the sporangium, attached to the peridial walls, as if to form septa, ordinary calcareous nodules few; spore-mass jet-black, spores, by transmitted light, violaceous, minutely roughened, 9-10 mu.

A very rare species, as it appears, easily recognized by the Coddington even, much more by the microscopic characters quoted; probably often overlooked by the collector, as to the naked eye it presents the appearance of some imperfectly developed, dried-up plasmodium. Very unlike _Physarum serpula_ Morgan, not infrequently offered by collectors as _Cienkowskia_. It is _Diderma reticulatum_ of Fries, who, strangely enough, thought it might be a plasmodial phase of _Diderma_ (i. e. _Leocarpus_) _fragile_ (_Syst. Myc._, III., p. 102).

Eastern United States, Europe, Java, Ceylon, California. See under _L. fragilis_, next following.

=7. Leocarpus= (_Link_) _Rost._

1809. _Leocarpus_ Link, _Diss._, I., p. 25.

Sporangia sessile, or short stipitate; peridial wall double, the outer thick, destitute of lime, polished, shining within and without, the inner very delicate, enclosing the capillitium and spores; capillitium of two, more or less, distinct systems, the one a delicate network of hyaline, limeless threads, the other calcareous throughout, or nearly so, the meshes large and the threads or tubules broad; columella none, although a pseudo-columella may sometimes be detected.

This genus was by Link established on characters purely external. Rostafinski supplemented Link's definition by calling attention to the peculiar character of the capillitium and to microscopic characters in general. The outer peridium is thick and strong, unlike the ordinary structure in _Physarum_. Some physarums, however, have a very similar outer wall; _P. brunneolum_, for instance; compare the peridium of _P. citrinellum_. In dehiscence and structure there is also some resemblance to some species of _Diderma_, and by Persoon and Fries the common species was so referred, but the capillitium is again definitive.

A critical study of all these things really begins with Rostafinski's microscope. Under his definition of the present genus _P. squamulosum_ Wingate and _P. albescens_ Ell. might well be entered here. Such course at present would but increase confusion, and until by future research the ontogeny of all these, and so their relationship, shall be more exactly known, the genus may be left with its historic species,--montotypic.

LEOCARPUS FRAGILIS (_Dickson_) _Rost._

PLATE VIII., Figs. 3, 3 _a_, 3 _b_.

1785. _Lycoperdon fragile_ Dickson, _Fasc. Pl. Crypt. Brit._, I.,
p. 25.
1795. _Diderma vernicosum_ Persoon, _Ust. Ann. Bot._, XV., p. 34.
1809. _Leocarpus vernicosum_ Link, _Diss._, I., p. 25.
1875. _Leocarpus fragilis_ (Dicks.) Rost., _Mon._, p. 132.

Sporangia gregarious or clustered, sessile or stipitate, obovoid, rusty or spadiceous-yellow, shining; peridium opening at maturity in somewhat stellate fashion; stipe filiform, white or yellow, weak and short; spores dull black, spinulose, 12-14 mu.

A common species, distributed through all the world, Iowa to Tasmania. Recognizable at sight by the form and color of the sporangia. In shape and posture these resemble the eggs of certain insects, and, occurring upon dead leaves, generally where these have drifted against a rotten log, they might perchance be mistaken for such structures. With no other slime-moulds are they likely to be confused. The outer peridium opens irregularly, or more rarely stellately. At centre of the capillitium is a calcareous core. The plasmodium is yellowish white, spread in rich and beautiful reticulations. _N. A. F._, 1123.

A plasmodiform gathering of this species which will be mistaken for an entirely different thing, is yellow, sessile, and has _adherent_ spores; looks like a badhamia, but is after all a leocarpus and probably belongs here. The spores are irregularly clustered and the badhamioid section of the capillitium seems now dominant.

California.

B. DIDYMIACEAE

=Key to the Genera of the Didymiaceae=

1. Fructification aethalioid 1. _Mucilago_

2. Fructification plasmodiocarpous, or forming more
often distinct sporangia.

_a._ Calcareous deposits crystalline, stellate 2. _Didymium_

_b._ Calcareous deposits amorphous, peridium double 3. _Diderma_

_c._ Calcareous deposits in form of scattered
scales 4. _Lepidoderma_

_d._ Peridium double, the outer gelatinous 5. _Colloderma_

=1. Mucilago= (_Mich._) _Adans._

1729. _Mucilago_ Micheli, _Nov. Pl. Gen._, in part.
1763. _Mucilago_ (Mich.) Adanson, _Fam. des Pl._, II., p. 7.
1791. _Spumaria_ Pers. in Gmelin, _Syst. Nat._, II., p. 1466.

Fructification aethalioid, consisting generally of large cushion-shaped masses covered without by a white foam-like crust; within, composed of numerous tubular sporangia, developed from a common hypothallus, irregularly branched, contorted and more or less confluent; the peridial wall thin, delicate, frosted with stellate lime-crystals, which mark in section the boundaries of the several sporangia; capillitium of delicate threads, generally only slightly branched, terminating in the sporangial wall, marked with occasional swellings or thickenings.

By the descriptions offered by most authors, and especially by Rostafinski's figures (_Mon._, Pl. ix.), a pronounced columella is called for in the structure of _Spumaria_. The individual sporangia rise from a common hypothallus, and occasionally portions of this run up and give to a sporangium the appearance of being stipitate. Sometimes also this upper extension of the hypothalline protoplasm passes beyond or behind the base of the sporangium or between two or more, and is more or less embraced by these in their confluent flexures. This, it seems, suggested Rostafinski's elaborate diagram, Fig. 158; at least, none other form of columella is shown by American materials at hand.

1. MUCILAGO SPONGIOSA (_Leyss._) _Morgan._

PLATE VII, Figs. 6, 6 _a_, 6 _b_.

1783. _Mucor spongiosus_ Leysser, _Fl. Hal._, p. 305.
1791. _Reticularia alba_ Bull., _C. Fl. France_, p. 92.
1791. _Spumaria mucilago_ Pers., Gmel., _Syst. Nat._, II., 1466.
1805. _Spumaria alba_ (Bull.) DC., _Fl. Fr._, II., p. 261.
1897. _Mucilago spongiosa_ (Leyss.) Morg., _Bot. Gaz._, XXIV., p. 56.

Aethalium white or cream-colored, of variable size and shape, half-an-inch to three inches in length and half as thick, the component sporangia resting upon a common hypothallus and protected by a more or less deciduous calcareous porous cortex; peridial walls thin, and where exposed iridescent, generally whitened by a thin coating of lime crystals; capillitium scanty, of simple, mostly dark-colored, slightly anastomosing threads; columella indefinite or none; hypothallus white, spongy; spore-mass black, spores violaceous, exceedingly rough, large, 12-15 mu.

Very common in all the eastern United States and the Mississippi valley, south to Texas. The plasmodium is dull white, of the consistence of cream, and is often met with in quantity on beds of decaying leaves in the woods. In fruiting the plasmodium ascends preferably living stems of small bushes, herbaceous plants, or grasses, and forms the aethalium around the stem some distance above the ground. The cortex varies in amount, is also deciduous, so that weathered or imperfectly developed forms probably represent the var. _S. cornuta_ Schum.

Two varieties of this species are recognized; the one from Bolivia, var. _dictyospora_ described by Mr. R. E. Fries (_Arkiv. for Botanik_ Bd. 1, p. 66) differs from the type chiefly in its finer capillitial threads its darker spores with longer spines and fine reticulate sculpture; the other from Colorado, var. _solida_ described by Professor Sturgis differs, as the name implies, principally in its greater compactness and slightly smaller calcareous crystals; a desert phase.

=2. Didymium= (_Schrad._) _Fr._

1797. _Didymium_ Schrad., _Nov. Gen. Plant._, p. 20, in part.
1829. _Didymium_ (Schrad.) Fr., _Syst. Myc._, III., p. 113.
1875. _Didymium_ (Schrad.) DeBy., Rost., _Versuch_, p. 13.

Sporangia distinct, stipitate, sessile or even plasmodiocarpous, never aethalioid; the peridium thin, irregular in dehiscence, covered with a more or less dense coating of calcareous crystals; columella more frequently present; capillitium of delicate threads, simple or sparingly branched, extending from the columella to the peridial wall.

The genus _Didymium_, as set up by Schrader _l. c._, included a number of species now assigned to _Diderma_, _Lepidoderma_ or _Lamproderma_. Fries set out the didermas; DeBary and Rostafinski completed the revision by setting out the remaining alien forms.

The genus is among Myxomycetes instantly recognized by the peculiar form of its calcareous deposits, stellate crystals coating, or merely frosting, usually distinct sporangia.

=Key to the Species of Didymium=

1. Lime-crystals merely whitening the peridial wall.

A. Fructification plasmodiocarpous.

_a._ White.

O Capillitium with adherent vesicles 1. _D. complanatum_

OO Capillitium simple 2. _D. anellus_

OOO Capillitium much combined; spores
10-13 mu 3. _D. wilczekii_

OOOO Capillitium crystal-bearing 18_a_. _D. anomalum_

_b._ Yellow or tawny 4. _D. fulvum_

B. Fructification normally of distinct sporangia.

_a._ Sporangia sessile or nearly so; outer
calcareous wall conspicuously developed 5. _D. crustaceum_

_b._ Sporangia plainly stipitate.

i. Peridium much depressed; umbilicate below.

O Stipe white 6. _D. squamulosum_

OO Stipe black.

+ Larger, about 7.5-1 mm. 7. _D. melanospermum_

++ Small, about .5 mm. 8. _D. minus_

+++ Sporangia discoid 9. _D. clavus_

ii. Peridium small, globose.

O Stipe dark brown or black; columella
dark, obsolete or none. 10. _D. nigripes_

OO Stipe generally paler, of various tints
of brown, orange, etc.

+ Columella pale or white, nearly
smooth 11. _D. xanthopus_

++ Columella, yellow, discoid, rough 12. _D. eximium_

iii. Peridium turbinate, columella
hemispheric 13. _D. trochus_

iv. Peridium annulate 14. _D. annulatum_

2. Calcareous crystals forming a distinct crust.

A. Fructification wholly plasmodiocarpous 15. _D. dubium_

B. Sporangia ill-defined, sessile, plasmodiocarpous.

_a._ Spores generally nearly smooth 16. _D. difforme_

_b._ Spores very rough, obscurely banded 17. _D. quitense_

EXTRA-LIMITAL

_a._ Sporangia discoid, spores reticulate 18. _D. intermedium_

_b._ Stipe, columella, peridium, orange-brown 19. _D. leoninum_

1. DIDYMIUM COMPLANATUM (_Batsch_) _Rost._

PLATE XVI., Fig. 8.

1786. _Lycoperdon complanatum_ Batsch, _Elench. Fung._, I., p. 251.
1829. _Didymium serpula_ Fr., _Syst. Myc._, III., p. 126, Rost.,
_App._, p. 21.
1875. _Didymium complanatum_ (Batsch), Rost., _Mon._, p. 151.
1899. _Didymium complanatum_ (Batsch) R., Macbr., _N. A. S._, p. 85.
1911. _Didymium complanatum_ Rost., List., _Mycetozoa, 2nd ed._,
p. 127.

Fructification plasmodiocarpous, creeping, flattened, vein-like, annulate or reticulate, the dark-colored peridium covered with white, but not numerous crystals; hypothallus none; columella none; capillitium much branched, violaceous threads combined to form a rather dense net which bears numerous, peculiar, rounded vesicles, yellowish in color, 30-50 mu in diameter; spores minutely warted, 7-9 mu, violaceous-brown.

The defining characteristics here are the curious supplementary vesicles. These are evidently plasmodic, embraced, shot-through, by all the neighboring capillitial threads, withal warted like a spore. They remind of the curious, belated, spore-like but giant cells found in stipes, as in arcyriaceous forms. With all the wealth of his prolix, poetic, metaphoric tongue, the Polish author gives them abundant consideration. In the _Mon._, Tab. IX., Figs. 166 and 180, he clearly shows the structure, although in the explanation of the plate he has strangely mixed this species with _D. crustaceum_ Fr. Under _D. serpula_ Fries may refer to the present species, although there is nothing in his description to determine the fact. The same thing may be said of the description and figures of Batsch. Rostafinski, in the _Monograph_, seems to have been satisfied as to the identity of Batsch's materials: in the _Appendix_, he writes _D. serpula_, but gives no reason.

Rare. New York. England, France, Germany.

2. DIDYMIUM ANELLUS _Morgan._

PLATE XVIII., Fig. 7.

1894. _Didymium anellus_ Morgan, _Jour. Cin. Soc._, p. 64.
1899. _Didymium anellus_ Morg., Macbr., _N. A. S._, p. 85.
1911. _Didymium anellus_ Morg., Lister, _Mycetozoa, 2nd ed._, p. 134.

Plasmodiocarp in small rings or links, then confluent and elongated, irregularly connected together, bent and flexuous, resting on a thin venulose hypothallus, or sometimes globose, the peridium dark colored, with a thin layer of stellate crystals, irregularly ruptured; capillitium of slender, dark-colored threads, which extend from base to wall, more or less branched, and combined into a loose net; columella a thin layer of brown scales; spores globose, very minutely warted, violaceous, 8-9 mu.

This minute species resembles a poorly developed, or sessile, phase of _D. melanospermum_. Some of the sporangia (?) are spherical; such show a very short dark stalk. The columella is scant, and the spores are smaller than those of _D. melanospermum_.

Ohio. Reported more recently from Europe and Ceylon.

3. DIDYMIUM WILCZEKII _Meylan_.

1908. _Didymium wilczekii_ Meyl., _Bull. Soc. Vaud. Sci. Nat._,
XLIV., p. 290.
1911. _Didymium wilczekii_ Meyl., List., _Mycetozoa, 2nd ed._, p. 134.

Plasmodiocarpous, dehiscing irregularly, columella scant; capillitium abundant, the threads brown, anastomosing, forming an elastic net; spores purple-brown, minutely spinulose, 10-12 mu.

Resembling plasmodiocarpous forms of _D. squamulosum_, a montane var.; small and delicate, our specimen about 16 x 6 mm. Evidently not common; collected but once by Professor Bethel at an altitude of 11,000 feet, Rocky Mountains of Colorado.

Reported in Switzerland and Sweden.

In certain Swiss gatherings made in 1913 Miss Lister finds capillitial threads with _spiral_ taeniae as in _Trichia_! (_Jour. of Bot._, Apr. 1914.) The threads in our specimen are roughened, somewhat as in _D. squamulosum_, though less strongly; the spores are nearly smooth, fuliginous at first, paler and violaceous when saturate.

4. DIDYMIUM FULVUM _Sturgis._

1917. _Didymium fulvum_ Sturgis, _Mycologia_, IX., p. 37.

Sporangia gregarious, sessile, elongate or forming curved plasmodiocarps, sometimes confluent, rarely sub-globose, concave beneath, pale-raw-umber in color, 0.5-0.8 mm. in diameter, occasionally seated on a concolorous, membranous, lime-encrusted hypothallus which may form pseudo-stalks; sporangium wall membranous, stained with yellow blotches, thickly sprinkled with clusters of large acicular crystals of pale-yellowish lime; columella very much flattened or obsolete; capillitium an abundant network of delicate, almost straight or flexuose, pale-purple or nearly hyaline threads, frequently with dark, calyciform thickenings as in _Mucilago_, and occasionally showing fusiform, crystalline blisters; spores dark-purplish-brown, coarsely tuberculate, the tubercles usually arranged in curved lines, paler and smoother on one side, 12.5 to 14.5 mu. Colorado.

5. DIDYMIUM CRUSTACEUM _Fr._

1829. _Didymium crustaceum_ Fr., _Syst. Myc._, III., p. 124.

Sporangia closely aggregated, globose, or by compression deformed, sessile, snow-white, by virtue of the remarkably developed covering of calcareous crystals by which each sporangium is surrounded as if to form a crust, the peridium membranous, colorless, usually shrunken above and depressed; columella pale, small, or obsolete; hypothallus scant or vanishing; capillitium of rather stout violaceous threads seldom branched except at the tips, where they are pale and often bifid, or more than once dichotomously divided; spores strongly warted, globose, violet-brown, 10-13 mu.

This species has in some ways all the outward seeming of a diderma, but cannot be referred to that genus because of the crystalline character of its crust. This is a very marked structure; loosely built up of very large crystals, it is necessarily extremely frail, nevertheless persists, arching over at a considerable distance above the peridium proper. Sometimes, however, caducous, evanescent.

The sporangia are said to be sometimes stipitate. This feature does not appear in any of the material before us. Lister in _Mycetozoa_ Pl. XL., _c._ draws the capillitium much more delicate than it appears in our specimens. The hypothallus is sometimes noticeable under some of the sporangia where closely crowded, but is not a constant feature.

Rostafinski (by typographical error?) confused in the _Monograph_, pp. 164, 165, this species with Persoon's _Physarum confluens_. In the _Appendix_ he substitutes the Friesian nomenclature. Persoon's description of his species is insufficient, and throws no light on the problem whatever.

Rare. Iowa; Black Hills, South Dakota. Reported common in Europe. Canada; Vancouver Island to the St. Lawrence.

6. DIDYMIUM SQUAMULOSUM (_Alb. & Schw._) _Fries._

1805. _Diderma squamulosum_ Alb. & Schw., _Consp. Fung._, p. 88.
1816. _Didymium effusum_ Link, _Diss._, II., p. 42.
1829. _Didymium squamulosum_ (Alb. & Schw.), Fries, _Syst. Myc._,
III., p. 118.
1875. _Didymium effusum_ (Link) Rost., _Mon._, p. 163.
1894. _Didymium effusum_ (Link) List., _Mycetozoa_, p. 99.

Sporangia, in typical forms, gregarious, globose or depressed-globose, gray or snow-white, stipitate; the peridium a thin iridescent membrane covered more or less richly with minute crystals of lime; the stipe when present, snow-white, fluted or channelled, stout, even; columella white, conspicuous; hypothallus usually small or obsolete; capillitium of delicate branching threads, usually colorless or pallid, sometimes with conspicuous calyciform thickenings; spores violaceous, minutely warted or spinulose, 8-10 mu.

This, one of the most beautiful species in the whole series, is remarkable for the variations which it presents in the fruiting phase. These range all the way from the simplest and plainest kind of a plasmodiocarp with only the most delicate frosting of calcareous crystals up through more or less confluent sessile sporangia to well-defined elegantly stipitate, globose fruits, where the lime is sometimes so abundant as to form deciduous flaky scales. The hypothallus, sometimes entirely wanting, is anon well developed, even continuous, venulose, from stipe to stipe. The capillitium varies much in abundance as in color; when scanty, it is colorless and in every way more delicate, when abundant, darker in color and sometimes with stronger thickenings.

_D. fuckelianum Rost._, as shown in _N. A. F._, 2090, and in some private collections, seems to be a rather stout phase of the present species; the stipe is more abundantly and deeply plicate, is sometimes tinged with brown, and the capillitium is darker colored and coarser than in what is here regarded as the type of the species; but withal the specimens certainly fail to meet the requirements of Rostafinski's elaborate description and figure, _Mon._, p. 161 and Fig. 154.

_D. effusum_ Link, probably stands for a sessile form of this species, but Link's brief description (1816) is antedated by the much better one of Albertini and Schweinitz, _l. c._

Generally distributed throughout the wooded regions of North America, from New England to Nicaragua, and from Canada to California. Not uncommon about stable-manure heaps, in flower beds, and on richly manured lands. July, August.

Nicaragua specimens not only show a continuous vein-like hypothallus, but have the peridia often confluent, the columellae in such cases confluent, the stipes distinct. Furthermore, the largest spores reach the limit of 12.5 mu, and perhaps the larger number range from 10-12.5 mu, and all are very rough. This corresponds with _D. macrospermum_ Rost., which is distinguished, says the author (_Mon._, p. 162, _opis_), "chiefly by the large and strongly spinulose spores." However, the same sporangium in our Central American specimens yield spores 9.5-12.5 mu, a remarkable range. So that _D. macrospermum_ on this side the ocean, at least, cannot be distinguished from _D. squamulosum_, as far as spores are concerned. A similar remark may be made relative to the form of the columella which Rostafinski, in his figures especially, would make diagnostic. The columella in the sporangia with largest and roughest spores is that of a perfectly normal _D. squamulosum_.

7. DIDYMIUM MELANOSPERMUM (_Pers._) _Macbr._

PLATE VII., Figs. 3, 3 _a._

1794. _Physarum melanospermum_ Pers., _Roem. N. Mag. Bot._, p. 89.
1797. _Didymium farinaceum_ Schrader, _Nov. Gen. Pl._, p. 26, t. 5,
Fig. 6.

Sporangia gregarious, hemispheric, depressed, umbilicate below, stipitate or sessile; the peridium firm, dull brown in color, frosted with minute crystals of lime, breaking irregularly; stipe, when present, short, stout, dull black, opaque, arising from a broad base or hypothallus; columella large, prominent; dark-colored, rough above, concave below; capillitium of more or less sinuous, usually dark-colored threads, sparingly branched, and often with calyciform thickenings; spore-mass black, spores by transmitted light pale, purplish-gray, spinulose or rough, 10-12 mu.

A well-marked and common species, distinguished by its depressed sporangium and dark-colored, opaque stipe. The latter is usually very short, almost completely concealed in the concavity of the umbilicate sporangium. The columella is dark-colored, forming the floor of the peridial cavity.

Persoon first named this species as here. Later on, _Uster's Ann._, XV., 6, he substituted _villosum_ as a more appropriate specific name. Schrader rejects both names given by Persoon as unsuitable, and suggests _farinaceum_. Schrad., _op. cit._, p. 27.

New England, Ohio, Missouri, Alabama, Iowa, Nebraska; Europe; probably cosmopolitan.

8. DIDYMIUM MINUS _Lister._

PLATE X., Figs. 4, 4 _a_, 4 _b_.

1892. _Didymium farinaceum_ Schr., var. _minus_, List., _Mycetozoa_,
p. 97.
1896. _Didymium minus_ List., Morg., _Jour. Cin. Soc._, p. 61.
1899. _Didymium minus_ List., Macbr., _N. A. S._, p. 89.

Sporangia gregarious, depressed-globose, umbilicate below, whitish or gray, small, about 1/2 mm., stipitate; stipe erect, rather slender, black, faintly striate, about equal to the sporangium in the horizontal diameter; columella distinct, dark brown, globose or depressed-globose, attaining in some cases the centre, rough; capillitium delicate, almost colorless, radiating, sparsely branched; spores in mass dark brown, by transmitted light violet-tinted, minutely roughened, 8-10 mu.

Probably more common than the preceding, and generally mistaken for it. Distinguished by its smaller size, longer and more slender stem, and general trim, well-differentiated appearance. Certainly very near the preceding, of which Mr. Lister regards it as merely a variety. Professor Morgan thought it in this country the more common form.

New York, Ohio, Iowa; reported from Europe, Africa, South America.

9. DIDYMIUM CLAVUS (_Alb. & Schw._) _Rabenhorst._

1805. _Physarum clavus_ Alb. & Schw., _Consp. Fung._, p. 96.
1829. _Didymium melanopus_ Fries, _Syst. Myc._, III., p. 114.
1844. _Didymium clavus_ (Alb. & Schw.) Rabh., _Ger. Cr. Fl._,
No. 2282.
1875. _Didymium clavus_ (Alb. & Schw.) Rost., _Mon._, p. 153.
1899. _Didymium clavus_ (Alb. & Schw.) Rabenh., Macbr., _N. A. S._,
p. 90.
1911. _Didymium clavus_ Rost., List., _Mycet., 2nd ed._, p. 128.

Sporangia gregarious, pale gray, discoid or pileate, depressed, stipitate; the peridium dark-colored, frosted with calcareous crystals above, naked below; stipe short, slender, tapering upward, furrowed, arising from a hypothallus more or less distinct, black; columella obsolete; capillitium of delicate threads, pale or colorless, little branched; spores violaceous, pale, nearly smooth, 6-8 mu.

This species is well differentiated, easy of recognition by reason of its peculiar discoid sporangium, calcareous above, naked and black beneath. _D. neglectum_ Massee, reported from Philadelphia, is said to be a slender form of the present species. The figures of _D. clavus_ by Albertini and Schweinitz are excellent, as also the description.

Not common. Pennsylvania, Ohio, Iowa.

10. DIDYMIUM NIGRIPES (_Link_) _Fries._

PLATE VII., Figs. 2, 2 _a_, 2 _b_.

1809. _Physarum nigripes_ Link, _Obs. Diss._, I., p. 27.
1818. _Physarum microcarpon_ Fr., _Sym. Gast._, p. 23.
1829. _Didymium nigripes_ (Link) Fr., _Syst. Myc._, III., p. 119.
1875. _Didymium microcarpon_ (Fr.) Rost., _Mon._, p. 157.
1896. _Didymium microcarpon_ Fr., Morg., _Jour. Cin. Soc._, p. 61.

Sporangia gregarious, globose or hemispheric, umbilicate beneath, small, white, stipitate; the peridium smoky, covered with minute calcareous crystals; stipe slender, erect, black, opaque; hypothallus scutate, black; columella distinct, globose, black or dark brown; capillitium of delicate threads, pale brown or colorless, with occasional brown thickenings or nodes, sparingly branched; spores pale, violaceous by transmitted light, minutely warted, 6-8 mu.

This is _D. microcarpon_ Rost. Fries, _l. c._, acknowledges the priority of Link's appellation, and discards _microcarpon_. Rostafinski adopted _microcarpon_ simply because he thought it more appropriate. Fries describes the columella "none or black." It is doubtful whether we have the typical Friesian form on this continent. The fructification is in our specimens small, about .4 mm., and the spores, as noted by Morgan, small; otherwise the species is hardly more than a variety of the next. Under the name _D. nigripes_ Lister groups our Nos. 10, 11, 12. _N. A. F._, 1393, represents Dr. Rex's conception of the present species.

Not common. New York, Ohio, Iowa.

11. DIDYMIUM XANTHOPUS (_Ditmar_) _Fr._

PLATE XVI., Fig. 10.

1817. _Cionium xanthopus_ Ditmar, Sturm, _Deutsch. Fl._, III., p. 37,
t. 43.
1829. _Didymium xanthopus_ (Dit.) Fr., _Syst. Myc._, III., p. 120.
1873. _Didymium proximum_ Berk. & C., _Grev._, II., p. 52.
1892. _Didymium microcarpon_ (Fr.) Rost., Macbr., _Bull. Lab. Nat.
Hist. Iowa_, II., p. 146, in part.
1894. _Didymium nigripes_ Fr., List., _Mycetozoa_, p. 98, in part.