Astrothelium prostratum, Stirton.

Thallus well developed, continuous or rimulose, thin, yellowish white, merging into grey or cinereous; apothecia compound; receptacle black, large, broad (.02 to .07 in.), shallow, scarcely raised above the general surface; perithecia entire, irregular in outline, and all apparently opening into one ostiole, which shows on the surface; spores eight, uniserial, colourless at first—when the contents are coarsely granular—becoming brown when mature, with six crossbars, which assume the appearance of oval, coloured cells; paraphyses plentiful, filiform, simple.

On bark of trees, Wainuiomata, Wellington.