t52 Cincinnati Society of .\atural History. 



of lime. Columella convex, roughened, white or yellowish, 

 sometimes scarcely developed. Capillitium rather scanty, of 

 slender colorless threads, sparingly branched, a.^cending from 

 the columella. Spores globose, minutely warted, violaceous, 

 8-IO mic. in diameter. 



Growing on old leaves, bark, moss, etc. Sporangia .4-.6 

 mm. in diameter, irregular and rugulose. On account of the 

 pulverulent coat of lime on the sporangium, Massee refers 

 the species back to Didymium, where it was placed by Fries. 



4. Dir)ERM.\ STROMATKUM, Link. Sporangia large, sub- 

 globose, depressed, irregular and angular from mutual pres- 

 sure, closely crowded together on a thick yellowish or pinkish 

 common hypothallus ; the wall smooth and even, grayish- 

 white or cinereous, with a thin closely connate outer layer of 

 minute granules of lime. Columella considerably elevated or 

 much depressed, convex, subglobose or quite irregular, white 

 or colored, as the hypothallus, especially at the base. Capilli- 

 tium of abundant colored threads, more or less branched and 

 combined into a loose net. Spores globose, minutely warted, 

 violaceous, 8-10 mic. in diameter. 



Growing on Hickorj' bark. The .sporangia .5-.8 mm. in 

 diameter, the suface smooth. Rostafinski, in his Monograph, 

 places this species as a variety of D. spumarioides, but in the 

 Appendix it is separated as a species. The sporangia are 

 quite different from those of D. spumarioides, but I can see no 

 difference in the spores. 



5. DiDERMA GLOBOSUM, Pers. Sporangia subglobose, more 

 or less irregular from mutual pressure, closely crowded to- 

 gether on a thick, white hypothallus, seated upon it or 

 usually sunk into its substance at the base ; the wall with a 

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

 distinct and sei)arable from the inner membrane, easily 

 breaking into fragments, and falling away : the inner mem- 

 brane very thin, rugulose, cinereous with granules of lime or 

 free from them and iridescent. Columella white, small, irreg- 

 ular, subglobo.se or ellipsoidal, rarely wanting. Capillitium 

 of slender, dark colored threads, more or less branched and 

 combined into a loose net. Spores globose, very minutely 

 warted, violaceous, 8-10 mic. in diameter. 



