224 Arber. — On the Past History of the Ferns. 
There is a further impression from the Lias of Poland, named Danaea 
microphylla by Raciborski \ in which the resemblance to the recent fructifi- 
cation is, perhaps, rather closer. 
Thus we find that although there is no evidence to show that the 
Eusporangiatae were a dominant group in Mesozoic times, there are 
apparently fairly good grounds for believing that this race was then in 
existence. But this conclusion, even on the present evidence, would have 
much greater weight than it appears to me to possess, were it not that 
there is at least a possibility, as yet to be disproved, that Taeniopteris itself 
may have been other than a true Fern. The suspicion that some of these 
Fern-like plants, possessing a fructification not unlike the synangia of 
a modern Eusporangiate Fern, may have been in reality the male organs of 
members of the Cvcadophyta, is at the bottom of our present difficulties 
with regard to the past history of the Eusporangiatae, as will be seen when 
we come to discuss possible members of this group in Palaeozoic times. 
The fact that in the male fronds of the Pteridosperms, and in the same 
organs of the Bennettiteae 2 , a group directly descended from the Pterido- 
spermae, as Dr. Scott 3 has shown, the whole male fructification is strikingly 
like that of the modern Marattiaceae, cannot be overlooked in this con- 
nexion. Also we know that as early as the Rhaetic, some of the 
Cycadophyta bore seeds, after the manner of the modern genus Cycas. 
The specimen described by Nathorst 4 , from the Rhaetic of Bjuf, in Sweden, 
under the name Cycadospadix integer , Nathorst, which I have had the 
pleasure of seeing recently, appears to me to be conclusive in this respect. 
If this is so, we should certainly expect to find, among the earlier Cycado- 
phyta, instances in which the male fructifications were not aggregated into 
cones, but borne on fronds, like the corresponding organs of the Pterido- 
sperms. At the present time, no suspicion attaches to Taeniopteris in this 
connexion, but it is a possibility still to be borne in mind, and one which 
renders, in my opinion, the otherwise excellent evidence that this genus 
was a Eusporangiate Fern, rather less conclusive. 
We know too little of the transition flora of the Palaeozoic and 
Mesozoic rocks to justify any attempt to seek for the Eusporangiate line of 
descent during that period at present. Raciborski 5 has indeed stated that, 
in the Lunzer Schichten (Keuper) of Austria, the rich flora of which has 
unfortunately never been worked out, 70 per cent, of the Ferns belonged to 
the Marattiaceae, but I am not aware of the evidence for this statement. 
The possibility, however, remains, as I have hinted with regard to the 
Leptosporangiatae, that a further study of the plants of this transition 
period may throw important light on the Eusporangiate life-line. 
When we turn to the Palaeozoic rocks, we find, as has been stated 
1 Raciborski (’ 94 ), p. 13 , pi. VI, figs. 1-6. 2 Wieland (’01). 8 Scott (’05 1 ), (’05 s ). 
4 Nathorst (’02), p. 6 , pi. I, fig. 11 . 5 Raciborski (’91). 
