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size and were of a firmer texture than the filmy ferns with which we are familiar ; but there is a 
New Zealand fern ( Loxsoma ) which has large, much-divided, coriaceous fronds, not unlike the 
Devonian plant, and yet is a true hymenophyllaceous fern. The uniform flabellate veins of the 
fossil occur in some filmy ferns, especially among those with simple fronds ; and the reduction 
of the pinnule to pedicellate veins in the fertile part of the frond is precisely what is met with in 
the fertile frond of the genus Feea , from Central America, which is reduced to a slender rachis, with 
a series of short pedicels on either side, each supporting a trichomanoid cup. Several fossils 
belonging to the same genus have been observed in rocks of Devonian age in North America, 
and a few species pass up into our Coal measures. Associated with Palceopteris in the Devonian 
rocks are the remains of another hymenophyllaceous fern, with venation and cutting of the 
frond more closely resembling the majority of the existing species of this group. 
The rocks of the Carboniferous period contain the most abundant materials for determining 
the nature of the plants which, in these remote ages, lived on the surface of the earth. Beds of 
coal are found in all parts of the world. These are the remains of forests which grew on the 
localities where the coal is found. The plants had for their soil the clay on which the beds of coal 
now rest, and their dead remains were covered by the clay sediment brought down by rivers into 
great lakes which, through changes in the level of the land, had submerged the low level tracts 
on which the forests grew. The under- and over-clays have, so to speak, hermetically sealed 
the enclosed plant remains. Whatever metamorphic changes were taking place within the beds, 
nothing could escape through the investing clays. The hydro-carbons fixed by the living plants 
of the Coal period — the “bottled sunshine” — have been preserved intact, but the individuality of 
the plants has been lost in the compact substance into which they are now converted. Happily, 
however, there occur in some beds of coal rounded masses of crystallised carbonate of lime, 
which, though only a trouble to the miner, are of the greatest service to the botanist. The lime 
has crystallised in these incombustible masses before the plants forming the coal had lost their 
form and structure. When cut by the lapidary into slices, to permit of microscopic examination, 
these nodules supply materials for forming an accurate estimate of the plants which formed the 
coal. In the under-clay the roots are still to be found, while leaves, branches, and fruits, floated 
down on the running water into the still lakes, are spread out on the old surfaces of the over-clay, 
and are there so preserved as to show the form and external markings with remarkable minute- 
ness of detail. The examination of these various materials have made it certain that coal is 
entirely composed of the altered remains of ferns, and their near allies the club-mosses and horse- 
tails. It is true that Gymnosperms, not far removed from our yew, were then important elements 
in the flora of the world ; their remains, however, do not occur in the coal itself, but are found 
under conditions which show that they have been carried from higher grounds. The club-mosses 
of the Palaeozoic period were represented by arborescent Sigillarias and Lepidodendrons, and 
the horse-tails by tree-like Calamites. Though differing greatly in size they agreed with living 
Lycopods and Equisetums in all essential characters. 
The ferns of the Carboniferous period are represented by some three hundred forms, so distinct 
that they have been described as separate species, and received technical names. Having only 
fragments of fronds to deal with, it is certain that the diversity of form, and the modifications in 
the venation in accommodation to their diverse forms, have led to the establishment of more 
species in our books than existed in connection with the known materials in nature. Yet, after 
the most liberal deductions have been made, there remains a great variety. They have been 
classified from the character of their venation, as the fructification has been observed in only a few 
cases. It is not possible, on account of the imperfect materials for classification, to give them 
