and brown at
the apex; spores brown, ellipsoid, 4-celled, 15 to 21 mic. long and 5.5
to 8 mic. wide.

Examined from Butler and Champaign Counties. On trunks and mossy rocks.
Rare and usually sterile in Ohio.

EXPLANATION OF PLATE XIV

Fig. 1. A section through the thallus of _Peltigera canina_, showing the
cortex above and the medulla below, the medullary hyphae of the lower
portion running in a somewhat horizontal direction. The algal cells
shaded. X 380.

Fig. 2. A section through the thallus of _Nephroma helvetica_, showing
the cortices, upper and lower, and the mycelial medulla within. The
algal cell shaded. X 760.

Fig. 3. A section through a cephalodium of _Peltigera aphthosa_; a, the
surrounding cortex; b, the internal hyphae and the cells of the algal
host; c, the supporting hyphae from the thallus below. Partly
diagramatic. X 48.

Fig. 4. A small portion of a section through the exciple of _Peltigera
canina_, showing the plectenchymatous structure. X 380.

[Illustration: PLATE XIV.]

EXPLANATION OF PLATE XV

Fig. 5. A section through the cortex of _Peltigera canina_, showing its
relation to the medullary hyphae. X 760.

Fig. 6. A portion of a section of the hymenium of _Peltigera canina_,
showing two asci containing spores, two asci with protoplasmic contents,
and five paraphyses. X 760.

Fig. 7. A portion of a section through an apothecium of _Peltigera
canina_, showing part of the hymenium of interwoven hyphae below and the
bases of three paraphyses above. X 760.

Fig. 8. Types of spores found in the _Peltigeraceae_: a, 4-celled spores
of _Peltigera horizontalis_; b, 6- to 8-celled spores of _Peltigera
sorediata_; c, 4-celled spores of _Peltigera aphthosa_; d, 4- to
8-celled spores of _Peltigera canina_. X 380.

The drawings were made with camera lucida and were reduced one-half
in making the plates.

[Illustration: PLATE XV.]

INDEX

Bacidia, 345

Bacidia egenuloidea, 346

Bacidia fuscorubella, 346

Bacidia incompta, 347

Bacidia inundata, 347

Bacidia rubella, 346

Bacidia schweinitzii, 347

Bacidia umbrina, 348

Biatorella, 336

Biatorella pruinosa, 337

Biatorella simplex, 336

Biatorina, 341

Biatorina chalybeia, 341

Biatorina heerii, 343

Biatorina lentibularis, 342

Biatorina prasina, 342

Bilimbia, 343

Bilimbia hypnophila, 344

Bilimbia melaena, 344

Bilimbia microcarpa, 345

Bilimbia naegelii, 344

Bilimbia