Chapter I: ANGIORIDIUM, Grev. Plasmodiocarp laterally compressed, more or less

elongated and flexuous, attached by the lower margin to the substratum, and, at maturity, regularly dehiscent along the upper margin by a longitudinal fissure; the wall a firm membrane, with the granules of lime forming a reticulate layer on the inner surface. Capillitium a loose, irregular net-work of tubules, extending from side to side, and containing large, irregular nodules of lime. Spores globose, violaceous.

A genus readily distinguished by its laterally compressed plasmodiocarp, splitting lengthwise by a regular fissure. The wall is a single membrane, and there is but a single reticulate layer of lime upon it, which is plainly on the inner surface.

1. ANGIORIDIUM SINUOSUM, Bull. Plasmodiocarp laterally compressed and very much flattened, more or less elongated and flexuous, sometimes confluent and branched or reticulate, without any hypothallus; the wall a more or less thickened and brownish membrane, the inner surface coated with a dense reticulately thickened white layer of lime, and often studded with the white nodules. Capillitium of hyaline tubules, forming a loose irregular net-work, with numerous broad vesicular expansions filled with lime; the nodules white, very large, irregularly lobed, and branched. Spores globose, very minutely warted, violaceous, 8-10 mic. in diameter.

Growing on old leaves, sticks, mosses, etc. Plasmodiocarp commonly about 1 mm. in height and 1-5 mm. in length, but the size is variable. The color appears to depend upon the thickening of the membrane; when it is thin and pellucid, the color is white or cinereous from the inner layer of lime and the contained spores; with a more thickened membrane, the color becomes ochraceous or brownish. _Physarum bivalve_ Pers. _Physarum sinuosum_ of Rostafinski's monograph.