18 
Ohio Biological Survey 
ascomycetes as to their origin and relationships would be to invite 
serious failure. Consequently, in preparing the system to follow, all the 
orders of ascomycetes have been considered, while many families that 
do not occur in our flora, and, consequently, do not appear in the outline, 
have been kept in mind, and have been discussed in part. How these 
families should be treated will be taken up more fully in the third paper 
of the series on “The nature and classification of lichens” (Fink 30 and 
31), in which the whole problem of the classification of ascomycetes will 
be reconsidered with such additional data as may come to light in the 
interval. 
As stated in the introductory paragraph of this paper, ascomycetes 
have been treated previously as a whole. Lists from Nebraska (Webber 
64 and 65) and California (McClatchie46) have distributed lichens 
among other ascomycetes, and certain writers (Bessey 6, 7 and 8; 
Clements 17 and 18; Fink 28, 29 and 31, and Schaffner 54) have either 
united all ascomycetes into one system or intimated that this method of 
treatment is in accord with present knowledge of the group. Certain 
European mycologists regard lichens as fungi, and some of them have 
either advocated their distribution among other fungi, or have admitted 
that they may, without inconsistency, be so treated (Fink 31). The dis¬ 
position proposed below is based on the belief that we have sufficient 
data, in part briefly outlined above, to warrant the distribution of lichens 
in the best manner possible in order that we may present relationships 
better and have a good basis for comparative studies of all ascomycetes. 
The statement in this paragraph expresses views that are held by various 
botanists and have been used in certain arguments, keys, catalogues of 
plants, and systems of classification cited. However, this series of 
papers will be the first to treat lichens as fungi with other ascomycetes in 
a descriptive catalogue. 
A summary regarding the arrangement of the orders and some of 
the families will elucidate some points. The Hemiascales {Herniascineae) 
of some authors have not been admitted, though Eremascus and some 
others of these plants may yet prove to be ascomycetes rather than 
phycomycetes. The Lahoulbeniales have been placed first in the outline 
of classification, since the work of Thaxter (6) and Faull (26 and 27) 
makes them undoubted though aberrant ascomycetes, apparently near to 
the Rhodophyceae, which have similar archicarpic characters. With 
respect to ascogenous structures, they must be regarded either degenerate 
or closely related to those members of the Rhodophyceae that produce 
ooblastema filaments, while the closed ascocarp would seem to indicate 
