222 
Arber . — On the Past History of the Ferns . 
were known by some special name. On a recent occasion I suggested the 
term Primofilices, in view of the fact that such, perhaps preferable, names as 
Archaeopterideae 1 and Palaeopterideae are not available for this purpose. 
This term, although not altogether satisfactory, has the advantage of sug- 
gesting the Primary or Palaeozoic Age of the race. 
One family of the Primofilices has already been recognized (the Botryo- 
pterideae), and possibly some at least of the detached annulate sporangia, 
known from structure specimens, belonged to other representatives. It seems 
probable that yet further examples will be discovered in the near future. 
On the other hand, certain of these Fern-like plants may have already begun 
to specialize along those lines which we see exhibited by the Mesozoic, 
Tertiary, and Recent Leptosporangiatae, and have thus become virtually 
members of that group. The evidence of some of the impressions men- 
tioned above suggests that this may well have been the case. If, however, 
we admit the possibility that the Primofilices were the immediate fore- 
runners of the Leptosporangiatae, the question as to whether Lepto- 
sporangiate Ferns existed in the Palaeozoic period becomes of minor 
importance. The ancestors naturally must be of much greater interest, 
at the .present moment, than the first descendants of a race which we know 
so well in the living state. 
One further conclusion should be borne in mind. Whether we regard 
the Botryopterideae as an ancient family, from which some of the Lepto- 
sporangiatae were later derived, or as a member of that group pure and 
simple, there can be no doubt that neither the Primofilices nor the Lepto- 
sporangiatae were, towards the close of the Palaeozoic period, in the 
position of dominant or ruling group, as compared with the Pteridospermae, 
or other of the great phyla, then at their maximum differentiation. 
The Eusporangiatae. 
When we turn to the geological evidence for the existence of the 
Eusporangiatae in past times, we have to deal with less trustworthy data. 
Until quite recently it has been generally held that this group of the Ferns 
was by far the most abundant and diversified in the Palaeozoic period. As 
Professor Bower expressed it in his paper, already referred to, ‘ recent 
writers have repeatedly remarked the preponderance of Ferns of the 
Eusporangiate type in primary rocks.’ And again, ‘ where the sporangia 
have been found, they are in the overwhelming majority of cases of a 
character allied to the Marattiaceae V In view, however, of the recent 
discovery by Mr. Kidston 3 of the male organs of Lyginodendron , which 
have proved to be the fossils long known under the name Crossotheca , and 
1 The term Archaeopterideae, suggested by Professor Lignier in this connexion (Lignier (’03), 
p. 103 footnote) cannot hold good, as it is already in use for a Devonian family of Fern-like plants, 
including the genus Archaeopteris. 
2 Bower (’91), p. 122. 
Kidston (’05 1 ); (’05 2 ). 
