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 destitute 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.