Part 1 (2/2)
The plants which have gone to make up the coal are not at once apparent to the naked eye We have to search a the shales and clays and sandstones which enclose the coal-seams, and in these we find petrified specimens which enable us to build up in our les and forests of these iether on the old forest floor of those days, is now apparent to us as coal
[Illustration: Fig 2--_Annularia radiata_ Carboniferous sandstone]
A very large proportion of the plants which have been found in the coal-bearing strata consists of numerous species of ferns, the number of actual species which have been preserved for us in our English coal, being double the nureater part of these do not see ferns, and, indeed, many of the species The impressions they have left on the shales of the coal-, and point to a time when the sandy clay which imbedded them was borne by water in a very tranquilthe them into their mass of future shale In one species known as the _neuropteris_, the nerves of the leaves are as clear and as apparent as in a newly-grown fern, the na ”nerve-fern” It is interesting to consider the history of such a leaf, throughout the ages that have elapsed since it was part of a living fern First it grew up as a new frond, then gradually unfolded itself, and developed into the perfect fern Then it beca waters, and buried beneath an accuone on in connection with the surface of the earth, it has lain dor-place exactly as we see it, until now excavated, with its conteetation, to form fuel for our winter fires
[Illustration: FIG 3--_Rhacopteris inaequilatera_ Carboniferous lireatly rese species, yet there were others in these ancient days utterly unlike anything indigenous to England now There were undoubted tree-ferns, similar to those which thrive now so luxuriously in the tropics, and which throw out their graceful crowns of ferns at the head of a naked stem, whilst on the bark are the marks at different levels of the points of attachment of former leaves These have left in their places cicatrices or scars, showing the places frost the tree-ferns found are _aphyton_, _paloeopteris_, and _caulopteris_, all of which have thesethat at one tiland
[Illustration: Fig 4--Frond of _Pecopteris_ Coal-shale]
One form of tree-fern is known by the name of _Psaronius_, and this was peculiar in the possession of rouped round the stem Some of the smaller species exhibit forms of leaves which are utterly unknown in the noned to them in accordance with certain characteristics which they possess This was the more possible since the fossilised impressions had been retained in so distinct a manner Here before us is a specimen in a shale of _pecopteris_, as it is called, (_pekos_, a coether unlike the well-known living fern _osmunda_ The position of the pinnules on both sides of the central stalk are seen in the fossil to be shaped so like a comb, or a sahilst up the centre of each pinnule the vein is as pro gracefully in the air, and but to-day imbedded in its shaly bed
[Illustration: FIG 5--_Pecopteris Serlii_ Coal-shale]
_Sphenopteris_, or ”wedge-fern,” is the naue-leaf”; _cyclopteris_, or ”round-leaf”; _odonlopteris,_ or ”tooth-leaf,” and many others, show their chief characteristics in the names which they individually bear
_Alethopteris_ appears to have been the common brake of the coal-period, and in some respects rese 6--_Sphenopteris Affinis_ Coal-shale]
In some species of ferns so exact are the representations which they have impressed on the shale which contains them, that not only are the veins and nerves distinctly visible, but even the fructification still remains in the shape of the marks left by the so-called seeds on the backs of the leaves So look at the coal speciood museum ell repay the time so spent
What are known as septarian nodules, or snake-stones, are, at certain places, common in the carboniferous strata They are coated around some central object, such as a fern-leaf or a shell When the leaf of a fern has been found to be the central object, it has been noticed that the leaf can sometimes be separated from the stone in the form of a carbonaceous filo by M Goppert to illustrate the process of fossilisation of ferns Having placed so ferns in a mass of clay and dried them, he exposed the reseree of heat to which they were subjected, the plants were found to be either brown, a shi+ning black, or entirely lost In the last mentioned case, only the ione to stain the surrounding clay black, thus indicating that the dark colour of the coal-shales is due to the carbon derived from the plants which they included
Another very proetation of the coal period, was that order of plants known as the _Cala ferns were so slight in uishable This resemblance between the ancient and the modern is not found so apparent in other plants The Cala resemblance, and were closely related, to our modern horse-tails, as the _equiseta_ are popularly called; but in some respects they differed considerably
Most people are acquainted with the horse-tail (_equiseturaceful plant, and stands erect with a jointed steed in whorls around the joints, and, unlike its fossil representatives, its joints are protected by striated sheaths The ste species rarely exceeds half-an-inch in diameter, whilst that of the calareat point which is noticeable in the fossil calareater height than any siht feet high In the nature of their stee to Dr Williaenous woody ste almost al ways disappeared has left the fluted stee consisted of whorls of long narrow leaves, which differed only frole-nerved Sir Willians the calamites to four sub-types: _calamite_ proper, _calae: FIG 7--Root of _Catae: FIG 8--_Cala used the word ”exogenous,” it , to the nomenclature and broad classification of the various kinds of plants We shall then doubtless find it far easier thoroughly to understand the position in the scale of organisation to which the coal plants are referable
[Illustration: FIG 9--_Asterophyllites foliosa_ Coal-anisation are known as _Cellular_ They are almost entirely composed of numerous cells built up one above the other, and possess none of the higher foranisation which are met with elsewhere This division includes the lichens, sea-weeds, confervae (green aquatic scui (mushrooms, dry-rot), &c
The division of _Vascular_ plants includes the far larger proportion of vegetation, both living and fossil, and these plants are built up of vessels and tissues of various shapes and character
All plants are divided into (1) Cryptogams, or Flowerless, such asFlowering plants are again divided into those with naked seeds, as the conifers and cycads (gymnosperms), and those whose seeds are enclosed in vessels, or ovaries (angiosperain divided into the monocotyledons, as the palms, and dicotyledons, which include most European trees
Thus:--
------------------------------------------------------------------- | (MA Brongniart) | |(Lindley) | |CELLULAR | | | | _Cryptogaens | | | lichens | | | | | | |VASCULAR | | | | _Cryptogaens | | | ) | | | | Gyens | | naked seeds) | cycads | | | Two or| | | | enclosed seeds) | | | | Monocotyledons |Palrasses | | | Dicotyledons |Most European |Exogens | | | trees and shrubs | | -------------------------------------------------------------------
Adolphe Brongniart terens,” because, as we shall see, of the great predoaens”