in diameter. _Diderma brunneolum_ Phillips. I have taken the description from Ma.s.see's monograph.

4. LEOCARPUS FRAGILIS, d.i.c.ks. Sporangium very large, obovoid-oblong, stipitate or subsessile; the wall a greatly thickened membrane, polished and shining within and without, from alutaceous or pale umber to dark-brown in color, dest.i.tute of lime. Stipe short, weak, and slender, arising from a thin hypothallus. Capillitium of slender tubules forming a loose network of large irregular meshes, with slight expansions at the angles; the lime white, variable in amount, sometimes quite scanty, then again filling large portions of the net-work with long-branched and reticulate ma.s.ses. Spores subglobose, dark violaceous, opaque, 12-15 mic. in diameter.

Growing gregariously on old wood, leaves, mosses, etc. Sporangium 1.5-2 mm. in length by 1 mm. in thickness, the stipe variable in length, but usually much shorter than the sporangium. _Diderma vernicosum_ Pers.

IV. PHYSARELLA, Peck. Sporangium oblong, stipitate; the apex re-entrant and confluent with the hollow columella; the wall a thin membrane covered with small scales and minute granules of lime, at maturity torn away at the apex and stellately splitting into a few segments. Stipe elongated, tapering upward, entering the sporangium and prolonged to the apex as a tubaeform columella. Capillitium distinguished by two distinct sets of tubules; the first consisting of long, thick tubules filled with lime, rising at regular intervals from the wall of the sporangium and extending to the columella; the second, of very slender threads, scarcely branched, and nearly dest.i.tute of lime, stretching between the wall and the columella. Spores globose, violaceous.

A genus founded upon the one remarkable species, and more distinct than any other from the typical genus of the Physaraceae. In fact, the structure of the sporangium is unique among the Myxomycetes.

1. PHYSARELLA OBLONGA, B. & C. Sporangium oblong, the apex re-entrant and confluent with the summit of the columella, the base obtuse or slightly umbilicate, stipitate, cernuous. The wall of the sporangium a firm, yellowish membrane, covered with minute granules and with scattered, small, yellow scales of lime; after maturity the apex is torn away more or less irregularly from the summit of the columella and the wall splits into a few segments, which become reflexed and are subpersistent about the base of the sporangium. Stipe long, erect or flexuous, the apex bent or curved, red-brown, rising from a small hypothallus, entering the sporangium and prolonged to the apex as a hollow tubaeform columella. Capillitium of thick, spiniform tubules filled with lime and slender, violet threads, extending between the wall and the columella. The tubules elongated, terete, tapering gradually from wall to columella, containing yellow granules of lime; the threads very slender, outwardly branched a time or two, the further extremities connected by short, lateral branches, often furnished with minute, free branchlets, and containing a few small, fusiform nodules of lime. Spores globose, nearly smooth, violaceous, 7-9 mic. in diameter.

Growing on old wood, bark, leaves, etc. Sporangium commonly .8-1.0 mm.

in length by .5-.6 mm. in diameter, the stipe 1-2 mm. long; the spiniform tubules measure 150-200 15-20 mic.

The abnormal forms of this species which sometimes manifest themselves are very singular; the sporangium has a tendency to dilate, becoming funnel-form or even salver-shaped, the stipe shortening and even disappearing. I have a large specimen which superficially resembles some lichen, a _Physcia_, for example; the sporangia are pressed down, flattened out, extremely irregular, and in many places confluent; the rudimentary stipes are hidden beneath the leafy expansions. In all the forms, however, may be uncovered the spiniform tubules mingled with the slender threads. This is _Trichamphora oblonga_ B. & C. _Tilmadoche oblonga_ of Rostafinski's monograph, and _Physarella mirabilis_ Peck.

V. CYTIDIUM, Morgan. Gen. nov. Sporangium globose or rarely ellipsoidal, stipitate; the wall a thin membrane, with an external layer of minute granules of lime, rupturing irregularly. Stipe more or less elongated, tapering upward and entering the sporangium as a columella. Capillitium of slender tubules, arising from the columella, repeatedly branching and anastomosing to form a regular net-work, the extremities attached on all sides to the wall of the sporangium, the tubules containing at intervals nodules of lime. Spores globose, violaceous.

This genus is readily distinguished from _Physarum_ by the columella, which gives origin to the capillitium; this feature indicates a relationship to _Didymium_ and to _Lamproderma_.

--1. EUCYTIS. Sporangium globose, the columella not reaching its center.

1. CYTIDIUM PULCHERRIMUM, B. & R. Sporangium globose, stipitate; the wall a thin lilac-tinted membrane, with a dense closely adherent layer of granules of lime, dark purple or wine-colored. Stipe long, erect, dark purple to purplish black, tapering upward and entering the sporangium as a slight obtuse columella. Capillitium of slender lilac tinted threads, forming a dense net-work of very small meshes, with slight expansion at the angles; the nodules of lime very small, numerous, dark purplish or vinose in color, ellipsoidal or obtusely angular. Spores globose, even, lilac, 7-9 mic. in diameter.

Growing on old wood. Sporangium .4-.5 mm. in diameter, the stipe two or three times as long; the lime-nodules about the size of the spores. The purple stain, which the sporangia leave on white paper, is made by the granules of lime; the spores color the paper violet. _Physarum pulcherrimum_ B. & Rav., and _P. atrorubrum_ Peck.

2. CYTIDIUM CITRINUM, Schum. Sporangium globose, the base slightly flattened or umbilicate, stipitate; the wall a thin membrane, covered with small scales of lime, yellow or greenish-yellow, breaking up and falling away at maturity. Stipe stout, erect, yellow, longitudinally rugulose, expanded at the base, tapering upward and entering the sporangium as a short obtusely conical columella. Capillitium of slender tubules, forming a dense net-work, with slight expansions at the angles; the lime-nodules numerous, roundish or ellipsoidal, variable in size, yellow. Spores globose, nearly smooth, violaceous, 7-8 mic. in diameter.

Growing on bark, leaves, mosses, etc. Sporangium .5-.6 mm. in diameter, the stipe from once to twice this length. This, the typical species, I have not seen in this country, but forms with the sporangium lemon-yellow and grayish-yellow, with the stipe golden-yellow, connect it with _C. rufipes_. It is _Physarum citrinum_ Schum. _Diderma citrinum_ of Fries., S. M.

3. CYTIDIUM RUFIPES, A. & S. Sporangium globose, sometimes a little depressed and the base umbilicate, stipitate; the wall a thin membrane, covered with small scales of lime, golden-yellow to orange in color, breaking up at maturity and falling away. Stipe variable in length, slender, from orange or orange-red to dark red in color, sometimes blackish below, rising from a thin hypothallus, tapering upward and entering the sporangium as a short obtuse columella. Capillitium of slender tubules, forming a dense net-work of very small meshes, slightly expanded at the angles; the nodules of lime small, numerous, ellipsoidal or obtusely angular, orange to red in color. Spores globose, nearly smooth, violaceous, 8-10 mic. in diameter.

Growing on old wood, mosses, etc. A very abundant species. Sporangium .5-.7 mm. in diameter, the stipe from once to twice as long. As here defined, the species includes _Physarum aurantium_ var. _rufipes_ A. & S., and _Physarum aureum_ var. _chrysopus_ Lev, which I am unable to keep separate; the variation in size of the spores is not in correspondence with the variations in color of the sporangia. _Physarum pulchripes_ Peck, and _Physarum petersii_ B. & C., mostly belong here.

The bright orange colors become dull or tawny with age and exposure to the weather.

4. CYTIDIUM RAVENELII, B. & C. Sporangium globose, stipitate; the wall a thin pellucid membrane, covered with small scales of lime, from gray or drab to pale umber in color, breaking up at maturity and falling away.

Stipe variable in length, concolorous with the sporangium or darker below, tapering upward and entering the sporangium as a short obtusely conical columella. Capillitium of tubules, forming a dense net-work of very small meshes, with slight expansions at the angles; the lime-nodules small, numerous, ellipsoidal or obtusely angular, gray or drab to pale umber in color. Spores globose, nearly even, pale violaceous, 7-9 mic. in diameter.

Growing on old wood, mosses, etc. Sporangium about .5 mm. in diameter, the stipe once to twice this length. The species as here described includes _Didymium ravenelii_ B. & C., _Physarum simile_ Rost., and _Physarum murinum_ Lister.

5. CYTIDIUM GLOBULIFERUM, Bull. Sporangium globose, the base sometimes flattened or slightly umbilicate, stipitate; the wall a thin, pellucid membrane, covered with small scales of lime, white, cream-colored, or sometimes pinkish, breaking up and falling away at maturity. Stipe variable in length, white or smoky-white, usually darker below, rising from a thin hypothallus, tapering upward and entering the sporangium as a short obtuse or conical columella. Capillitium of slender tubules, forming a dense, persistent net-work of very small meshes, more or less expanded at the angles; the nodules of lime variable in size, numerous, white, roundish, ellipsoidal or obtusely angular. Spores globose, nearly even, pale violaceous, 7-9 mic. in diameter.

Growing on old wood, bark, mosses, etc. A very common and abundant species. Sporangium .5-.6 mm. in diameter, the stipe from once to two or three times this length. The lime nodules in the capillitium are sometimes round and quite minute, then again they are large and obtusely angular; the columella varies from very short and conical to longer and more cylindric. _Diderma globuliferum_ of Fries S. M., _Physarum albicans_ Peck. The specimens with the columella well nigh obsolete, may be _Tilmadoche columbina_ Rost.

6. CYTIDIUM MELLEUM, B. & Br. Sporangium globose, stipitate or subsessile; the wall a thin yellowish membrane, rugulose, covered by large irregular scales of lime, honey-color to golden-yellow, breaking up irregularly. Stipe short, sometimes very short or nearly obsolete, snow-white, expanding at the base into a small white hypothallus, tapering upward and entering the sporangium as a short obtusely conical columella. Capillitium a loose net-work of delicate tubules with broad vesicular expansions containing much lime; the nodules numerous, white or sometimes yellow, large, irregular, lobed, and branched. Spores globose, nearly even, pale violaceous, 7-9 mic. in diameter.

Growing on old leaves, sticks, herbaceous stems, etc.; not uncommon in this region. Sporangium .4-.5 mm. in diameter, the stipe about the same length or much shorter. _Didymium melleum_ B. & Br. _Didymium chrysopeplum_ B. & C. also belongs here and not with _C. citrinum_.

--2. REXIELLA. Sporangium ellipsoidal or pyriform, the columella prolonged nearly to the apex of the sporangium.

7. CYTIDIUM PENETRALE, Rex. Sporangium ellipsoidal or pyriform, stipitate; the wall a thin pellucid membrane, covered with small scales of lime, yellow-gray to greenish-yellow, rupturing at maturity into two to four segments. Stipe long, slender, translucent, pale red to dark red in color, tapering upward, entering the sporangium and prolonged nearly to the apex as a slender columella. Capillitium of very slender tubules, radiating from numerous points of the columella, forming a delicate net-work of very small meshes, scarcely expanded at the angles; the nodules of lime small, not numerous, roundish or obtusely angled, white or yellowish. Spores globose, very minutely warted, pale violaceous, 5.5-6.5 mic. in diameter.

Growing on old wood. A rare and singular species. Sporangium .5-.7 mm.

in height by .3-.5 mm. in diameter, the stipe two or three times the height of the sporangium. There is an affinity between this species and the _Physarella_. The obscure _Tilmadoche hians_ Rost., may be the same as the present species.

EXPLANATION OF PLATE XIII.

Fig. 49.--Angioridium sinuosum, Bull. _a._ Plasmodiocarp 5 _b._ Capillitium and spores 500.

Fig. 50.--Cienkowskia reticulata, A. & S. _a._ Plasmodiocarp 5. _b._ Piece of plasmodiocarp 90. _c._ Capillitium and spores 500.

Fig. 51. Leocarpus fragilis, d.i.c.ks, _a._ Sporangia 5. _b._ Capillitium and spores 500.

Fig. 52.--Leocarpus caespitosus, Schw. _a._ Sporangia 5. _b._ Capillitium and spores 500.

Fig. 53.--Physarella oblonga, B. & C. _a._ Sporangia 5. _b._ Sporangia 90. _c._ Capillitium and spores 500.

Fig 54--Cytidium penetrale, Rex. _a._ Sporangia 5 _b._ Sporangia and columella 90. _c._ Capillitium and spores 500.

Fig. 55.--Cytidium globuliferum, Bull. _a._ Sporangia 5. _b._ Sporangia 90. _c_. Columella 90 _d._ Capillitium and spores 500.

[Ill.u.s.tration: The Journal of the Cin. Soc. Natural History.

VOL. XIX. PLATE XIII.

MORGAN ON MYXOMYCETES]

VI. CRATERIUM, Trent. Sporangium obovoid to cylindric, stipitate; the upper and usually greater part of the wall covered with granules of lime, the basal portion naked and more persistent. Stipe short or sometimes elongated, arising from a small circular hypothallus, longitudinally plicate, confluent above and similarly colored with the base of the sporangium. Capillitium of tubules, forming a loose network, bearing numerous large angular and irregular nodules of lime, which are often confluent along the axis of the sporangium into a pseudo-columella. Spores globose, minutely warted, violaceous.

In this genus the sporangium is commonly obovoid, with a naked base which is confluent with the stipe and similarly colored; after dehiscence there is left behind the more persistent cyathiform portion standing on the substratum.

--1. EU-CRATERIUM. Sporangium at maturity dehiscent in a regular circ.u.mscissile manner, the apex falling away as a lid, leaving behind the more persistent cup-shaped portion.

1. CRATERIUM MINUTUM, Leers. Sporangium cyathiform, stipitate; the lid slightly convex, discrete from the first, usually depressed below the rim of the cup, falling away at maturity, and leaving a smooth, circular margin to the lower cyathiform portion. The wall a thick, firm, yellow-brown membrane, the outer surface of the cup entirely naked, smooth and shining, varying greatly in color from alutaceous or ochraceous to various shades of brown; the lid usually whitened by a thin layer of granules of lime. Stipe short, erect or bent, and slightly curved at the apex, varying in color from rusty yellow to reddish brown, longitudinally plicate, arising from a small, circular hypothallus.

Capillitium of tubules forming a loose net-work, bearing large, irregular, white nodules of lime, which are sometimes confluent in the axis of the sporangium. Spores globose, very minutely warted, violaceous, 8-10 mic. in diameter.

Growing on old wood, sticks, leaves, etc. Sporangium, together with the stipe, .8-1.4 mm. in height and .3-.5 mm. in diameter, the stipe usually shorter than the sporangium, sometimes equal to it in length, rarely longer. The latest authorities include the three species _Craterium vulgare_, _C. pyriforme_, and _C. minutum_ of Rostafinski's monograph all in one species.

2. CRATERIUM CONCINNUM, Rex. Sporangium usually minute, broadly funnel-shaped, stipitate; operculum always more or less convex, rarely approaching a hemispherical shape, dehiscent in a regular circ.u.mscissile manner. The wall a thick, brownish membrane, externally smooth and variously colored, sometimes uniformly light or dark umber, sometimes dark brown below and brownish white above; the operculum brownish white, darkest in the center. Stipe short, dark brown, longitudinally ridged.

Capillitium of tubules forming a close-meshed net-work, bearing small rounded or slightly angular nodules of lime, ochre-brown in color.

Spores globose, very minutely warted, brown, 9-10 mic. in diameter.

Growing usually upon chestnut-burs, and frequently a.s.sociated with _Lachn.o.bulus globosus_. Sporangium .5-.8 mm. in height including the stipe and .2-.5 mm. in diameter at the top, the stipe equaling the sporangium in length. It is readily distinguished by its small nodules in the capillitium, which are invariably of a dull, brownish-ochre color.

3. CRATERIUM RUBESCENS, Rex. Sporangium subcylindric or elongated cyathiform, stipitate; the apex convex, at maturity separating by an irregular line in a circ.u.mscissile manner. The wall dark violet-red, smooth, except at the upper portion, which is slightly roughened by an external deposit of scattered lime-granules of a pale, lilac color.