Sporangia sessile or plasmodiocarp; the wall a thin membrane, with a more or less thickened outer layer of minute brownish scales and granules. Capillitium of long and very slender tubules, proceeding from numerous points of the sporangial wall, loosely branched, forming no evident network, the surface minutely warted or spinulose. Spores globose, oval, or somewhat irregular, yellow.

The order is distinguished by the sessile sporangia, with thick brown walls, and the very slender threads of the capillitium, with irregular and indefinite markings.

Table of Genera of PerichÆnaceÆ.

• 1. PerichÆna. Sporangia more or less depressed, roundish or more commonly polygonal and irregular, dehiscent in a circumscissile manner.
• 2. Ophiotheca. Plasmodiocarp terete and more or less elongated, bent and flexuous, sometimes annular or reticulate, irregularly dehiscent.

I. PERICHÆNA, Fr. Sporangia more or less depressed, roundish or more commonly polygonal and irregular, the edges approximate and sometimes confluent; the wall a thin membrane, with a thick dense yellow-brown outer layer of minute scales and granules, becoming darker at the surface, dehiscent in a circumscissile manner. Capillitium of very slender loosely-branched threads, with the surface minutely warted. Spores globose, oval or somewhat irregular, yellow.

Distinguished from Ophiotheca by the flattened sporangium with a regular circumscissile dehiscence.

1. PerichÆna depressa, Lib. Sporangia very much depressed, polygonal, irregular, crowded, the edges contiguous, sometimes confluent; the wall thick, yellow-brown within and scarcely impressed by the spores; the outer surface smooth, brown-red to brown or blackish in color, dehiscent in a circumscissile manner. Capillitium of slender loosely-branched threads, 1–3 mic. in thickness, the surface merely uneven or very minutely warted. Spores globose, yellow, 9–10 mic. in diameter. See Plate I, Fig. 13.

Growing on the inside of the bark of Juglans, Acer, etc. Sporangia variable in size, 7–1.3 mm. in breadth, irregular and angular, much flattened. It is said to include PerichÆna vaporaria, Schw.

2. PerichÆna irregularis, B. & C. Sporangia depressed, irregular, polygonal, crowded, the edges contiguous and sometimes confluent; the wall thick, yellow inside and faintly reticulately impressed by the spores, the outer surface smooth, purplish-brown, dehiscent in a circumscissile manner. Capillitium of slender-loosely branched threads, about 2 mic. in thickness, the surface minutely warted or spinulose. Spores subglobose, yellow, 9–10 mic. in diameter.

Growing on the outer bark of Acer, etc. Sporangium .5-.6 mm. in width, closely crowded and irregular. It is much smaller than PerichÆna depressa, and its threads are more distinctly warted and spinulose.

3. PerichÆna corticalis, Batsch. Sporangia globose, the base depressed, gregarious: the wall thick, yellow within and distinctly reticulately impressed by the spores, the outer surface reddish-brown or yellow-brown in color, dehiscent in a circumscissile manner. Capillitium of slender loosely-branched threads, about 2 mic. in thickness, the surface very minutely warted. Spores subglobose, yellow, 10–12 mic. in diameter.

Growing on the inside of the bark of Elm. Sporangia .5-.6 mm. in diameter, quite regular in shape, with a slightly flattened base. My specimens are from Prof. McBride, of Iowa.

4. PerichÆna marginata, Schw. Sporangia depressed, polygonal, approximate and sometimes confluent, the surface cinereous-pulverulent, seated on a silvery hypothallus; the wall firm, thick, the outer surface yellow-brown, covered with minute whitish scales, the inner surface yellow, deeply reticulately impressed by the spores which rest against it, dehiscent in a circumscissile manner. Capillitium consisting of a few simple or somewhat branched threads or well-nigh obsolete. Spores subglobose, yellow, 12–14 mic. in diameter.

Growing on the outer surface of the bark of Acer, Fagus, etc. Sporangia .4-.6 mm. in width. This is plainly PerichÆna cano-flavescens, Raunkier. I do not find any threads of a capillitium in my specimens.

II. OPHIOTHECA, Currey. Plasmodiocarp terete and more or less elongated, bent and flexuous, sometimes annular or reticulate, the surface not polished or shining: the wall a thin membrane, with a thin outer layer of minute scales and granules, irregularly dehiscent. Capillitium of very slender loosely-branched threads, with the surface minutely warted and spinulose. Spores globose, oval or somewhat irregular, yellow.

Distinguished from PerichÆna by the terete plasmodiocarp and by the more spinulose capillitium. Cornuvia of Rostafinski.

1. Ophiotheca chrysosperma, Currey. Plasmodiocarp globose or oblong to elongated, and bent or flexuous, sometimes annular or branched and reticulate, dull brown in color; the wall a thin yellowish membrane, with a thin yellow-brown outer layer, irregularly dehiscent. Capillitium of slender loosely-branched threads, 2–3 mic. in thickness, the surface minutely spinulose. Spores subglobose, yellow, 8–9 mic. in diameter.

Growing on the inner surface of old bark of Quercus, etc. Plasmodiocarp .4-.5 mm. in thickness, variable in length. Cornuvia circumscissa of Rostafinski's monograph.

2. Ophiotheca Wrightii, B. & C. Plasmodiocarp more or less elongated, bent and flexuous, very commonly in small rings, from brownish-ochre to brown or blackish in color, not polished; the wall a thin yellow membrane, with a thin brown outer layer, irregularly dehiscent. Capillitium of slender loosely-branched threads, 2–3 mic. in thickness, furnished with numerous straight or bent long-pointed spinules. Spores subglobose, yellow, minutely warted, 10–12 mic. in diameter. See Plate I, Fig. 14.

Growing on the inside of bark of Acer, Carya, etc. Plasmodiocarp about .5 mm. in thickness, variable in length, often in small rings 1–2 mm. in diameter. The prickly threads are quite characteristic; the spinules are 3–5 mic. in length. Hemiarcyria melanopeziza, Speg., is evidently the same thing.

3. Ophiotheca vermicularis, Schw. Plasmodiocarp terete and more or less elongated, bent and flexuous, sometimes annular or reticulate, the surface not polished, brownish in color; the wall a thin yellow membrane, covered on the outside by a more or less thickened brown layer of scales and granules, irregularly dehiscent. Capillitium of slender loosely branched threads, 2–3 mic. in thickness, the surface with minute warts and ridges. Spores subglobose, yellow, 10–12 mic. in diameter.

Growing on the inside of old bark. Plasmodiocarp about .4 mm. in thickness and various in length; in my specimens the sporangia are mostly small rings. The species looks exactly like Ophiotheca Wrightii, but the character of the threads is quite different.

4. Ophiotheca pallida, B. & C. Plasmodiocarp terete, oblong or elongated annular and flexuous, the surface dull, pale ochraceous; the wall a thin pellucid membrane, minutely granulate, with a thin pale ochraceous outer layer, irregularly dehiscent. Capillitium of slender loosely-branched threads, 2–3 mic. in thickness, the surface minutely warted or spinulose. Spores subglobose, pale yellow, 10–12 mic. in diameter.

Growing on dead stems of herbaceous plants. Plasmodiocarp .3-.4 mm. in thickness, variable in length, sometimes short and roundish or oblong, sometimes much elongated and flexuous. More delicate than Ophiotheca vermicularis, and distinguished by its pallid color throughout.