38 
Ohio Biological Survey 
larger area, or finally to the family as a whole. It is evident that the 
taxonomic value of the diagnostic characters used, both morphological 
and physiological, may be lietter known after a large number of species 
has been studied carefully, but it is not probable that extension of the 
method given herein will involve other than minor modifications. 
In deciding on a method of treatment of the algal host, other 
ascomycetous lichens which will require treatment similar to that which 
is given to the Collemaceac in this paper were kept in mind. Other 
nosticolous lichens may be treated in essentially the same manner as the 
Collemaceac. Other types are illustrated by Epliebc, the thallus of which 
is similar to that of the Collemaccce, but is found penetrating throughout 
the tissue of the branched, filamentous alga, Sirosiplion, and by 
Coenogonium, which has a mycelial thallus that covers a portion of the 
filaments of the algal host, Trentcpohlia. From a purely technical point 
of view, it would be better, in treating the Collemaceac and all other 
lichens which require special methods for disposition of the modified 
algal host, to treat the host in a paragraph following the description and 
dealing with habitat and distribution. However, the practical advantage 
of placing immediately under the name of the species that which is first 
noticed in field or laboratory is so great that all who use our descriptions 
will doubtless agree that we are justified in departing from a more exact 
scientific procedure sufficiently to place the statement about the trans¬ 
formation of the algal host before the description of the lichen, which, 
excepting its apothecia, is known only through microscopic study. 
The penetration of the thallus of members of the Collemaceac 
throughout the algal-host colony as a distinct mycelial structure unat¬ 
tached to the algal cells (Fig. 1) renders the somatic areas so plainly 
visible that even the sexual reproductive areas, imbedded in the vegetative 
structures, are much more readily visible in section than those of most 
other lichens. In beginning our work, it was thought that these re¬ 
productive structures, so plainly visible, might be available in this family 
of lichens for diagnostic purposes. The archicarps (Fig. 18) and the 
spermagonia (Fig. 25) were carefully described for each species of 
Synechoblastus studied, and later those of a majority of the species of 
our other genera were more or less carefully examined, even though the 
work on Synechoblastus indicated that these organs do not dififer enough 
in the various species examined to make them of diagnostic value, except 
in a few instances. Added to this is the difficulty, sometimes very great, 
of finding specimens that bear the sex organs, and the areas of the thallus 
in which these organs occur. 
