us 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

Thallus foliose, with plectenchymatous cortex above (Fig. 5), or both
above and below (Fig. 2), with medulla of loosely interwoven hyphae,
trichomatic hyphae, usually present, attached to the substratum by
compound rhizoids; apothecia of considerable size, commonly on extended
lobes, usually imbedded in the tissues on the upper side, or more rarely
on the lower side; exciple inconspicuous; hypothecium usually light or
darker brown; hymenium usually pale below and brown or tinged brown
above; paraphyses simple or branched, distinct, seldom gelatinized or
coherent; spores hyaline or brown, 4- to several-celled, elongat