5. STEMONITIS WEBBERI, Rex. Sporangia subcylindric, the apex obtuse, tapering gradually downward, growing close together on a common hypothallus. Stipe and columella black and smooth, the stipe very short, the columella extending nearly or quite to the apex of the sporangium, the upper part usually flexuous. Capillitium composed of slender, flexuous brown threads; these immediately branch and anastomose several times, forming an interior network of very large meshes; the superficial network consisting of large irregular meshes, sometimes much elongated.

Spores globose, very minutely warted, brown, 7-9 mic. in diameter. See Plate XI, Fig. 34.

Growing on old wood, bark, etc. Sporangium with the stipe 5-10 mm. in height, the stipe 1-2 mm. in length, the sporangium .3-.4 mm. in thickness; meshes of the superficial net of the capillitium 40-100-150 mic. in extent. This is a much smaller species than _Stemonitis splendens_, and the structure of the interior network of the capillitium is entirely different.

6. STEMONITIS SPLENDENS, Rost. Sporangia linear-cylindric, obtuse at the apex, growing close together on a conspicuous hypothallus. Stipe and columella black and shining, the stipe very short, the columella reaching nearly or quite to the apex of the sporangium, often flexuous above. Capillitium composed of brown threads, variable in thickness, often with membranaceous expansions; the primary branches some of them simple or only branched above, others with a few anastomosing branchlets, forming an interior network of extremely large meshes; the superficial network consisting of large, irregular, roundish or polygonal meshes. Spores globose, very minutely warted, brown, 7-9 mic.

in diameter. See Plate XI, Fig. 33.

Growing on old wood. Sporangium with the stipe 15-25 mm. in height, the stipe 4-6 mm. in length, the sporangium about .4 mm. in thickness; the meshes of the superficial network of the capillitium 25-50-80 mic. or sometimes as much as 100 mic. in extent. This is _Stemonitis Morgani_, Peck.

V. ENERTHENEMA, Bowm. Sporangium regular, globose, stipitate; the wall thin and fragile, fugacious. Stipe stout, thick, tapering upward, entering the sporangium and prolonged to its apex, there expanding into a discoid membrane. Capillitium originating from the lower surface of the apical disk of the columella; the threads branched a few times and hanging downward, their extremities free. Spores globose, violaceous.

A well-marked genus, by reason of the peculiar origin of the capillitium.

1. ENERTHENEMA PAPILLATUM, Pers. Sporangium globose, stipitate; the wall brown or blackish, soon disappearing. Stipe black, rugulose, thick below, tapering above into the slender columella, which, at its apex, expands into a thin membranaceous disk. Capillitium of long brown threads suspended from the apical disk, the threads branched a few times, occasionally anastomosing by a short, transverse branchlet, the free ends often forked. Spores globose, very minutely warted, violaceous, 10-12 mic. in diameter. See Plate XI, Fig. 35.

Growing on old wood. Stipe and columella .8-1.2 mm. in height. The species seems to be rare in this country, as I have met with it but once myself, and have received only a few specimens from elsewhere.

VI. DIACHaeA, Fr. Sporangia globose to oblong, stipitate, arising from a common hypothallus; the wall thin, rugulose, iridescent with metallic tints, breaking up irregularly and gradually falling away. Stipe and columella thick, erect, rigid, tapering upward, filled with minute, roundish granules of lime, white or yellowish in color. Capillitium arising from numerous points of the columella, the threads repeatedly branching and anastomosing to form an intricate network, attaining the wall by numerous short free extremities. Spores globose, violaceous.

This genus is scarcely to be distinguished from Lamproderma, except by the white ma.s.s of lime which fills the tube of the stipe and columella.

1. DIACHaeA LEUCOPODA, Bull. Sporangia ovoid-oblong to short cylindric, the base obtuse or slightly umbilicate, the apex more rounded; the wall with bronze, blue, purple, and violet tints, gradually falling away.

Stipe short, thick, white, arising from a white, venulose, hypothallus, tapering upward; the columella cylindric or slightly tapering, obtuse, terminating below the apex of the sporangium. Capillitium of slender, flexuous brown threads forming a dense network of rather small meshes.

Spores globose, very minutely warted, violaceous, 7-9 mic. in diameter.

Growing on old leaves, sticks, etc., and sometimes running over living plants. Sporangium with the stipe 1-2 mm. in height, the stipe usually much shorter than the sporangium, the latter .4-.5 mm. in thickness.

_Diachaea elegans_, Fr.

2. DIACHaeA SPLENDENS, Peck. Sporangia globose, sometimes a little depressed, with the base umbilicate; the wall steel-blue with tints of purple and violet, quite persistent, rupturing irregularly. Stipe short, thick, white, arising from a white, reticulate hypothallus, tapering upward; the columella oblong or short cylindric, extending beyond the center of the sporangium. Capillitium of slender, brown threads, which branch several times and form a loose network of rather large meshes.

Spores subglobose, with very large warts, dark violet, 8-10 mic. in diameter.

Growing on old leaves and twigs. Sporangium .4-.6 mm. in diameter, the stipe about the same length. This is a beautiful species.

3. DIACHaeA THOMASII, Rex. Sporangia globose, or sometimes a little depressed; the wall gold-bronze, with tints of purple and blue, subpersistent, rupturing irregularly. Stipe thick, dull ochre-yellow in color, variable in length, usually very short and sometimes quite obsolete, arising from an ochre-yellow hypothallus; the columella varying from bluntly-conical to cylindric-clavate, attaining the center of the sporangium. Capillitium of slender, brown threads, radiating from all points of the columella, branching several times and forming a loose network of elongated meshes. Spores globose, minutely warted, violaceous, 11-12 mic. in diameter. See Plate XI, Fig. 36.

Growing on sticks, leaves, etc. Sporangium .5-.7 mm. in diameter, the stipe usually shorter or sometimes wanting. This species has been found only in the mountains of North Carolina. I am indebted to Dr. George A.

Rex for my example. In its structure the species is essentially a Lamproderma, but the stipe and columella are stuffed with granules of lime.

EXPLANATION OF PLATE XI.

Fig. 25.--Sectional view of the capillitium and stipe of Clastoderma De Baryanum, Blytt.

Fig. 26.--Section through the capillitium, columella and stipe of Lamproderma arcyrionema, Rost.

Fig. 27.--Perpendicular section through Lamproderma violaceum, Fr.

Fig. 28.--Perpendicular section through Lamproderma scintillans, Berk.

Fig. 29.--Section through the capillitium, columella and stipe of Comatricha Ellisii, Morgan.

Fig. 30.--Sectional view through the capillitium and columella of a portion of Comatricha crypta, Schw.

Fig. 31.--Sectional view through the columella and capillitium of a portion of Comatricha longa, Peck.

Fig. 32.--A portion of the capillitium of Stemonitis tenerrima, B. & C.--A sectional view through the columella above and below a view of the superficial network.

Fig. 33.--A portion of the capillitium of Stemonitis splendens, Rost.--A sectional view through the columella above and below a view of the superficial network.

Fig. 34.--The capillitium of a very short sporangium of Stemonitis Webberi, Rex; the breadth, however, somewhat exaggerated.

Fig. 35.--Showing the stipe, columella, apical disk and pendent capillitium of Enerthenema papillatum, Pers.

Fig. 36.--Perpendicular section through the capillitium, columella, and stipe of Diachaea Thomasii, Rex.

NOTE.--The figures of the objects are drawn as they appear under a magnifying power of about 100 diameters.

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

VOL. XVI. PLATE XI.]

ORDER VII.--DIDYMIACEae.

Sporangia simple and subglobose, or plasmodiocarp, rarely combined into an aethalium. Wall of the sporangium a thin membrane with an outer layer composed of minute stellate crystals, or of minute roundish granules of lime; these either lie singly upon the surface, or are compacted into a crustaceous coat. Stipe present or often wanting; the columella usually conspicuous and well-developed. Capillitium consisting of very slender, often sinuous threads, which extend from the base of the sporangium or from the columella to the walls, either simple or outwardly branching a few times at a sharp angle, combined into a loose irregular net by a few transverse branchlets, which are situated chiefly at the extremities.

Spores globose, violaceous.

This order is readily distinguished from the Physaraceae by the absence of lime from the threads of the capillitium.

TABLE OF GENERA OF DIDYMIACEae.

_a. The lime on the wall of the sporangium in the form of minute stellate crystals._

1. DIDYMIUM. Sporangium simple, subglobose and stipitate, the base commonly umbilicate, or sometimes sessile and plasmodiocarp.

2. SPUMARIA. aethalium composed of numerous elongated irregularly-branched sporangia, closely compacted together and confluent.

_b. The lime on the wall of the sporangium consisting of minute roundish granules._

3. DIDERMA. Wall of the sporangium with the outer calcareous layer usually compacted into a smooth continuous crust.

4. LEPIDODERMA. Wall of the sporangium with an outer layer of large scales, consisting of bicarbonate of lime.