Fig. 13. An ascus of _Buella parasema_, containing 8 spores. X 450. The figures were outlined with camera lucida and drawn on the table, close to the base of the microscope, 100 mm. below the stage. They were reduced one-half in making the plate. Figures 2, 10, and 11 are partly diagrammatical. [Illustration: PLATE XIII.] THE ASCOMYCETES OF OHIO V[B] The Peltigeraceae. LEAFY J. CORRINGTON. Two genera, _Peltigera_ and _Nephroma_, constitute the _Peltigeraceae_ as represented in the flora of Ohio. The thallus is plainly foliose with the margins of the lobes usually ascending and is gray-green to brown in color. The lower surface is often conspicuously veined. There are two pronounced distinctions between the two genera. _Peltigera_ has a well-developed cortex on the upper side of the thallus only (Fig. 1), while in _Nephroma_ there is a well-developed cortex on both upper and lower sides (Fig. 2). The position of the apothecia constitutes another distinction. In both genera the apothecia are marginal or submarginal on the lobes, which are usually narrow and somewhat extended; but in _Peltigera_ they are immersed in the upper surface, while in _Nephroma_ they are imbedded in the lower surface. _Peltigera_ furnishes seven species for Ohio, while only one species of _Nephroma_ has thus far been found in the State. The algal hosts are usually _Dactylococcus_ or _Polycoccus_, and both hosts are sometimes found in the same thallus. The chains of cells are usually badly broken up, and the nature of the algal host is, therefore, difficult to distinguish. Other algae doubtless sometimes occur in the thalli of _Peltigerae_. _Nephroma_ with cortex on both sides, is to be regarded higher than _Peltigera_, which has the cortex on the upper side only. The family is most closely related to the _Stictaceae_, from which family it is kept distinct on account of the absence of cyphellae and the difference in disposition of the apothecia. The collecting on which this paper is based was partly by Bruce Fink in connection with general collecting of fungi in Butler County and in collecting in Adams, Warren, Fairfield, Preble, Ross, Highland, and Lake counties for the Ohio Biological Survey. However, a considerable amount of material found by other collectors and previously reported from Ohio was examined. Hence, the collecting for the Ohio Biological Survey added little to knowledge of the _Peltigeraceae_ of Ohio, except in way of addition to distribution in the State. [Footnote B: Contributions from the Botanical Laboratory of Miami University--XIX] _Systematic Account._ PELTIGERACEAE