Chapter VI: DIACHÆA, 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 mass of lime which fills the tube of the stipe and columella.

1. DIACHÆA 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. _Diachæa elegans_, Fr.

2. DIACHÆA 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. DIACHÆA 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 Diachæa Thomasii, Rex.

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

VOL. XVI. PLATE XI.]

ORDER VII.--DIDYMIACEÆ.

Sporangia simple and subglobose, or plasmodiocarp, rarely combined into an æthalium. 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 Physaraceæ by the absence of lime from the threads of the capillitium.

TABLE OF GENERA OF DIDYMIACEÆ.

_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. Æthalium 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.