227 
Arber. — On the Past History of the Ferns. 
the stem of Psaronius , we have features which undeniably indicate close 
affinity to the modem Marattiaceae. To Mr. Kidston 1 , who regards 
Asterotheca as above the suspicion of being a male organ of a Pteridosperm, 
this difficulty of course does not exist. 
So far, we have discussed only those Palaeozoic fossils which resemble 
the modern Marattiaceae. Of the Ophioglossaceae we have, in the Primary 
rocks, almost as little trace as in the Secondary. There is, it is true, the 
Permian fossil from Autun in France, which Renault 2 described under the 
name Ophioglossites antiquus , but the evidence for this attribution is 
extremely doubtful. So far as I am aware, not even a plausible case has 
been made out at present to show that the Ophioglossaceae occur in either 
the Mesozoic or the Palaeozoic rocks. 
It will be seen, from what has been said above, that the task of tracing 
back the life-line of the Eusporangiate Ferns to the Palaeozoic period is 
beset by difficulties. There are at least some grounds for believing, either 
that they then existed, or that in the Palaeozoic rocks we are dealing with 
their direct ancestors. Which is the correct view we can hardly decide at 
present. It may be that in Palaeozoic times the Fern line of descent had 
not become clearly differentiated into Eusporangiate and Leptosporangiate. 
Dr. Scott 3 has already suggested that the Botryopterideae combine cha- 
racters common to the Ophioglossaceae and the Leptosporangiate Ferns. 
Possibly the origin of the Eusporangiatae is to be also sought for in the 
group which I have termed the Primofilices, of which the Botryopterideae 
are the best-known family at present. But until we know more of the 
exact nature of the Marattiaceous-like fructifications of the Palaeozoic 
rocks we are hardly in a position to speculate with advantage on these 
points, or to trace back the life-line of modern Eusporangiate Ferns with 
any certainty. One fact, however, stands out very clear. The evidence, 
formerly regarded as beyond suspicion, that the Eusporangiate Ferns 
formed a dominant feature of the vegetation of the Palaeozoic period, has 
been undermined, more especially by the remarkable discovery of the male 
organs of Lyginodendron by Mr. Kidston. At the best, we can only now 
regard them as a subsidiary group in that epoch in the past history of the 
vegetable kingdom. 
The Hydropterideae. 
The remaining group, the Heterosporous Ferns, may be briefly dismissed. 
So far as I understand the evidence, there are no satisfactory grounds, at 
present, for believing that this race existed at all in Palaeozoic times. 
I am aware that statements to the contrary are numerous ; in fact there 
exists a small literature on the subject of Palaeozoic Hydropterideae. 
2 Renault (’ 96 ), p. 30, pi. 82, figs. 7, 9, 
3 Scott (’ 00 ), p. 506. 
1 Kidston (’ 05 2 ), p. 162. 
