7. CYTIDIUM PENETRALE, Rex. Sporangium ellipsoidal or pyriform, stipitate; the wall a thin pellucid membrane, covered with small scales of lime, yellow-gray to greenish-yellow, rupturing at maturity into two to four segments. Stipe long, slender, translucent, pale red to dark red in color, tapering upward, entering the sporangium and prolonged nearly to the apex as a slender columella. Capillitium of very slender tubules, radiating from numerous points of the columella, forming a delicate net-work of very small meshes, scarcely expanded at the angles; the nodules of lime small, not numerous, roundish or obtusely angled, white or yellowish. Spores globose, very minutely warted, pale violaceous, 5.5-6.5 mic. in diameter. Growing on old wood. A rare and singular species. Sporangium .5-.7 mm. in height by .3-.5 mm. in diameter, the stipe two or three times the height of the sporangium. There is an affinity between this species and the _Physarella_. The obscure _Tilmadoche hians_ Rost., may be the same as the present species. EXPLANATION OF PLATE XIII. Fig. 49.--Angioridium sinuosum, Bull. _a._ Plasmodiocarp × 5 _b._ Capillitium and spores × 500. Fig. 50.--Cienkowskia reticulata, A. & S. _a._ Plasmodiocarp × 5. _b._ Piece of plasmodiocarp × 90. _c._ Capillitium and spores × 500. Fig. 51. Leocarpus fragilis, Dicks, _a._ Sporangia × 5. _b._ Capillitium and spores × 500. Fig. 52.--Leocarpus caespitosus, Schw. _a._ Sporangia × 5. _b._ Capillitium and spores × 500. Fig. 53.--Physarella oblonga, B. & C. _a._ Sporangia × 5. _b._ Sporangia × 90. _c._ Capillitium and spores × 500. Fig 54--Cytidium penetrale, Rex. _a._ Sporangia × 5 _b._ Sporangia and columella × 90. _c._ Capillitium and spores × 500. Fig. 55.--Cytidium globuliferum, Bull. _a._ Sporangia × 5. _b._ Sporangia × 90. _c_. Columella × 90 _d._ Capillitium and spores × 500. [Illustration: The Journal of the Cin. Soc. Natural History. VOL. XIX. PLATE XIII. MORGAN ON MYXOMYCETES] VI. CRATERIUM, Trent. Sporangium obovoid to cylindric, stipitate; the upper and usually greater part of the wall covered with granules of lime, the basal portion naked and more persistent. Stipe short or sometimes elongated, arising from a small circular hypothallus, longitudinally plicate, confluent above and similarly colored with the base of the sporangium. Capillitium of tubules, forming a loose network, bearing numerous large angular and irregular nodules of lime, which are often confluent along the axis of the sporangium into a pseudo-columella. Spores globose, minutely warted, violaceous. In this genus the sporangium is commonly obovoid, with a naked base which is confluent with the stipe and similarly colored; after dehiscence there is left behind the more persistent cyathiform portion standing on the substratum.