44 
Ohio Biological Survey 
related to many lichens and other ascoinycetes. These relationships are 
considered in the previous jiaper of this series. 
Eleven genera of Collcmaccac are recognized in Engler and Plantl’s 
“Naturlichen Phanzenfainihen.” Of the genera recognized in Engler 
and Prantl, only Physma, Leptogium, and Collema are known in North 
America. However, there seems to be no sufficient reason for exclud¬ 
ing the monotypic North American genus, Hydrothyria, from the 
Collemaceae. Seven of the foreign genera are monotypic, and the other 
one is ditypic. Of approximately 200 species of the Collemaceae, some¬ 
what more than half occur in North America. 
Thirteen species of the Collemaceae had been listed for Ohio when 
we began our work three years since. Of these, Synechoblastiis crystas- 
pis, Collema crispiim, Leptogium juniperinum and Mallotium myochroum 
do not seem to occur in the state, the determinations being faulty or rest¬ 
ing on insufficient or sterile material. Our studies have added seven 
species to the flora of Ohio, two of which are new. The total number of 
species now known for the state is sixteen. Besides this, the species with 
internal reproductive organs remains to be described. Sets of the material 
on which this paper is based may be found in the state herbarium and 
in the herbarium of Bruce Fink. 
During most of the time that we have worked on the Collemaceae of 
Ohio, Miss Leafy J. Corrington has given her forenoons to the work 
under our direction, and we are under obligations to her for assistance. 
Systematic Account 
COLLEMACEAE 
Thallus, with rare exceptions, composed wholly or mainly of a 
mycelium which penetrates throughout and usually surrounds the algal- 
host colony; hyphse not attached to the cells of the hosts in any of our 
species; the mycelial structure surrounded, in the higher genera, by a 
cortical plectenchyma, usually a single layer of cells, except around and 
below the apothecia; attached to the substratum by hyphal rhizoids, 
which are usually seen only in sections; female sex organ an archicarp, 
differentiated into an ascogonium and a trichogyne; male sex organ usually 
a spermagonium, which contains spermatia, but sometimes an internal 
spermatium (antheridium, or antheridial conidium?) ; external conidia 
known in one member of the family; apothecia with an exciple, either 
plectenchymatous or of interwoven hyphae, a hypothecium, the structure 
