On the Past History of the Ferns. 
BY 
E. A. NEWELL ARBER, M.A., E.L.S., F.G.S. 
Trinity College , Cambridge ; University Demonstrator in Palaeobotany. 
With a Diagram in the Text. 
U NTIL quite recently the belief has been current that, in the Palaeozoic 
period, and more especially in Carboniferous times, the True Ferns 
were sufficiently abundant to form one of the more characteristic groups of 
the then existing vegetation. Also that, of the two great divisions, the 
Eusporangiatae were, at that period, by far the most numerous and 
diversified. In the light, however, of recent Palaeobotanical research on 
the nature of the fructifications of the Cycadofilices, and other Palaeozoic 
Fern-like plants, our ideas on this subject are rapidly undergoing consider- 
able modification. The problems connected with the ancestry of modern 
Ferns have been rendered, if anything, more complex and difficult of 
solution than before. It is proposed to consider briefly here some aspects 
of the present position of our knowledge of the Palaeozoic and Mesozoic 
Ferns. 
The point of view adopted will be essentially that of the Geological 
Record. At the outset, we may distinguish carefully between the problem 
as to whether a particular race or family was actually in existence during 
any particular geological period, and the question whether that race had 
then attained to the position of a dominant 1 or ruling factor in the 
vegetation of the day. The former is not always capable of solution, 
but the latter can be answered with confidence in the great majority of 
cases. 
It will perhaps be helpful in this consideration of the ancestry of 
modern Ferns to approach the Geological Record in a somewhat novel 
1 The term 1 dominant ’ as used here, and in my ‘ Catalogue of the Glossopteris Flora,’ is intended 
to imply the adjectival sense of ‘ ruling.’ A dominant type is one of several races, which at any 
particular geological period constituted the more important and characteristic features of that flora. 
Thus, in the present day flora, among the higher plants, the Dicotyledons, Monocotyledons, Coni- 
ferales, and Filicales are the dominant groups. 
[Annals of Botany, Vol. XX. No. LXXIX. July, 1906.] 
Q 
