72 
“ The Origin of Gymnosperms ” 
dominant or ruling groups in Palaeozoic times. The Botryopterideae 
were the only family of Primofilices that had been clearly defined. 
He proposed to leave in abler hands the discussion of the connexion 
between the Botryopterideae and the modern Leptosporangiatae. 
He would however call attention by means of lantern slides to 
the sporangial structure of the Botryopterideae, which clearly did 
not agree in detail with that of a modern Leptosporangiate fern. 
It was, however, with the Eusporangiatae, that he would be 
chiefly concerned that night, because it presented special difficulties. 
Did they exist in the Mesozoic ? Did they exist in the Palaeozoic ? 
If so, what was their relationship to the Leptosporangiatae? 
These were problems which were necessarily pushed to the front 
by the progress of contemporary research. If we search the records, 
can we find any period in which Eusporangiatae had attained the 
dominant phase ? The life-line of a group of plants could, in his 
opinion, be represented by a lenticular figure stretching through, 
perhaps, several periods of the world’s history, the breadth of the 
figure at any point being proportional to the number and variety of 
the forms existing at that time. With regard to the Ophioglossaceae, 
there was no good evidence atall of their existence either in Palaeozoic 
or Mesozoic times. He knew of no fossil put forward as a possible 
representative of the Ophioglossaceous type, which would to-day 
be regarded as trustworthy evidence of the occurrence of that family. 
Such evidence as we had related rather to the other Eusporangiate 
family, the Marattiaceae. In older Mesozoic rocks, such as the 
Rhaetic, ai very few examples could be recalled. Tceniopteris was one 
of these. T. Minister}, a typical Rhaetic plant, bore synangia closely 
comparable with those of Marattia. Danceopsis had compound 
fronds whose pinnae were like the whole frond of Tceniopteris , and 
in some cases the synangia resembled those of the recent Dancea. 
But there was a suspicion that ' Tceniopteris might be the frond of ai 
Cycad bearing microsporangiate synangia. At any rate, whether 
these plants were really Marattiaceous or not, there was certainly no 
evidence that the Eusporangiatae were a dominant group in the 
Mesozoic. In the Palaeozic rocks, however, we did find a plexus of 
plants which had for many years been regarded as being true 
Eusporangiate types. These were the Pecopterids, which had exan- 
nulate sporangia, either independent or united to form synangia. 
What was their precise nature ? Were they true homosporous ferns, 
or were they male fronds of Pteridosperms ? To this question we 
could give, at the moment, no decided answer. He was inclined to 
think, however, that the latter alternative was the more likely. There 
were three points of great significance in this regard. First there 
was the discovery that Pecopteris Pluckeneti was seed-bearing, and 
although it was not quite a typical Pecopteris, this seemed no 
sufficient reason for dissociating it from the group. Secondly there 
was the recent discovery by Mr. Kidston of the microsporangiate 
organs of Lyginodendron, which were exannulate fern-like sporangia. 
Thirdly there were the Bennettiteae, the microsporangiate fronds of 
which were very Marattiaceous-like in structure, the microsporangia 
being united into synangia. If this were so, how much more likely 
was it that the Pteridosperms themselves, the direct ancestors 
of Bennettiteae, should have had similar microsporangiate fronds. 
He would exhibit a lantern slide shewing typical Pecopterid 
leaflets bearing synangia. He now came to Psaronius, a 
