EXPLANATION OF PLATE XIII


Fig. 1. Five paraphyses of _Rhizocarpon alboatrum_ to illustrate types
of simple and branched forms found in the same hymenium. X 450.

Fig. 2. A section of the thallus of _Bacidia rubella_ and two cells of
the woody substratum: a, the upper densely interwoven portion of the
thallus; b, part of the less densely interwoven portion below; c, the
algal-host cells; d, one of the cells of the woody substratum and three
hypal rhizoids within it. X 450.

Fig. 3. Spores of _Lecidea enteroleuca_ to illustrate the simple,
hyaline type. X 760.

Fig. 4. Spores of _Biatorina chalybeia_ to illustrate the 2-celled,
hyaline type. X 760.

Fig. 5. Spores of _Bilimbia trachona_ to illustrate the several-celled,
hyaline, fusiform or dactyloid type. X 760.

Fig. 6. Spores of _Bacidia fuscorubella_ to illustrate the
several-celled, hyaline, acicular type. X 760.

Fig. 7. Spores of _Bacidia umbrina_ to illustrate the several-celled,
hyaline, hamate or spirally twisted type. X 760.