192 



Description. Thallus at first continuous but becoming at 

 last cracked ; from greenish and grayish assuming a fuscous 

 hue, but yet of a general aspect of inky-black. Apoihecivm 

 rising from the thallus and invested ^vith a thalloid exterior 

 covering, which disappearing, leaves it in the form of a globose or 

 somewhat conical, superficial and somewhat prominent, black 

 wart, furnished with a papillated ostiole or pore. Niidevs white 

 with numerour short clavate asci, each of which contains two 

 large muriform, brown-colored spores. Paraphyses few and 

 nearly abortive. As the apothecia mature and grow older, 

 their form becomes somcAvhat truncate-conical, the papilla and 

 nmbilicated form of the ostiole disappears, while the scales of 

 the cracked thallus are bent upwards at their edges and seem 

 inclined to become pulverulent. 



Detected in August, 1855, on the shores of Bartholo- 

 mew's Pond, near Salem, Mass. 



The larger rocks in some of our smaller fresh- water streams, 

 such as are used for mill purposes, are often covered with a 

 slimy mass of fibrous substances, that peels off in crisped flakes 

 of several inches extent after the water has been for several 

 days so drawn away as to expose them to the sun and air. These 

 flakes are greenish-black in color, are tough and fibrous, yet 

 tearino- lengthwise somewhat like paper. They are composed 

 of entangled filaments of species of Oscillatoria, a minute 

 confervoid alga, and which grows parasitically upon aquatic 

 mosses. 



Upon the smooth upper surfaces of these flaky strata, very 

 minute, black specks can be distinguished, which at first are of 

 a spherical outline, but afterward become somewhat flattened. 

 They are in effect the perithecia of a Verrucarla, consisting of 

 a delicate, single cellular layer, or at least of very thin layers 

 of epidermis, within which are large curved-clavate asci, each 

 containing six to eight bi and triseptate elliptical spores. The 

 thallus is very rudimentary and is confined to green round gon- 

 idia lying somewhat contiguous to each other on the layer of 

 the Oscillatoria. 



