Under this name we may provisionally include those rounded spherical bodies found in the coal and its accompanying beds, and also in the Erian, which may be regarded as Macrospores or Sporocarps of Protosalvinia, or other Rhizocarpean plants akin to those described above in [Chapter III], which see for description.
Genus Protosalvinia.—Under this we include sporocarps allied to those of Salvinia, as described in [Chapter III].
Family Filices.
Under this head I shall merely refer to a few groups of special interest, and to the provisional arrangement adopted for the fronds of ferns when destitute of fructification.
The external appearances of trunks of tree-ferns have been already referred to.
With respect to tree ferns, the oldest known examples are those from the Middle Devonian of New York and Ohio, which I have described in the “Journal of the Geological Society,” 1871 and 1881. As these are of some interest, I have reproduced their descriptions in a [note] appended to Chapter III, which see.
The other forms most frequently occurring in the Carboniferous are Caulopteris, Palæopteris, and Megaphyton[DE] Stems showing merely masses of aërial roots are known by the name Psaronius.
[DE] See my “Acadian Geology,” also below.
With reference to the classification of Palæozoic ferns, this has hitherto been quite arbitrary, being based on mere form and venation of fronds, but much advance has recently been made in the knowledge of their fructification, warranting a more definite attempt at classification. The following are provisional genera usually adopted: