7 he Myxomycetcs of the Miavii Valley, Ohio. 153 



Growing on old leaves. Sporangia .5-. 8 mm. in diameter, 

 the surface smooth and polished. 



6. DiDERMA CRUSTACEUM, Peck. Sporangia subglobose, 

 irregular from mutual pressure, closely crowded together on 

 a thick, vellowish-while common hypothallus, and at the 

 base confluent with its substance ; the wall with a creamy 

 white, smooth, crustaceous outer layer of lime, distinct and 

 separable from the inner membrane, and easily breaking up 

 and falling away; the inner membrane very thin, rugu- 

 lose, cinereous and iridescent. Columella whitish or cream 

 colored, small, irregular, subglobose or ellipsoidal, often 

 wanting. Capillitium of slender, uneven, dark colored 

 threads, branched and combined into a loose net. Spores 

 globose, minutely warted, violet-black, opaque, 12-15 ^ic. in 

 diameter. Plate XII, Fig. 45. 



Growing on old leaves, sticks, etc. A common species in 

 this country. Sporangia .7-1.0 mm. in diameter, the surface 

 even but finely pulverulent rather than polished. CJiondrio- 

 dernia affine, Rost., is said to be the same species. It is 

 readily distinguished from D. globosion by the much larger 

 spores. 



^3. AsTROTiUM. Sporangia gregarious, scattered, or some- 

 times crowded and confluent, often much depressed, sessile, 

 rarely stipitate ; the hypothallus none or very scanty. 



7. DinERMA MiCHELii, Lib. Sporangia orbicular, very 

 much depressed, often umbilicate above and concave under- 

 neath, stipitate or sessile, gregarious, with the margins of the 

 sporangia sometimes confluent. The wall with a white crus- 

 taceous layer of lime, which soon ruptures around the edges, 

 allowing the upper part to break in pieces and fall away ; the 

 inner membrane cinereous, rupturing irregularly. Stipe 

 short, stout, erect, arising from a small, circular hypothallus, 

 whitish or alutaceous, longitudinally rugulose, expanding at 

 the apex, the wrinkles running out as veins on the under side 

 of the sporangium ; the columella much flattened, lenticular 

 or discoid, alutaceous or pinkish. Capillitium of very slender, 

 colorless threads, simple or forking a time or two, and con- 

 nected by short branchlets at the extremities. Spores glo- 

 bose, even, violaceous, 7-9 mic. in diameter. 



