GEOGNOSY AND GEOLOGY. 157 
The vertebrate sub-kingdom is represented by a few remains of fishes, 
principally teeth, belonging to the Hybodontes. Pl. 37, fig. 72, represents 
a tooth of Cladodus marginatus. 
Various hypotheses have been suggested as to the origin of the coal beds. 
Some of these suppose an accumulation of drift-wood, and others that the 
vegetation was produced in the spot where the coal is now found. 
The latter assumption appears the more probable of the two, demanding, 
however, a greater length of time, although not so great as would perhaps 
be required at the present day. The most convincing proof of the 
indigenous origin of at least many of the coal beds is found in the fact, that 
tree-stems are found standing upright in sandstone strata of the 
carboniferous, at right angles to the stratification, and partly carbonized, 
partly pyritized. In some piaces it may be clearly seen that the roots of 
such stems were implanted in beds of slate clay. A curious instance of this 
is found in a coal mine near Treuil, not far from St. Etienne, as shown in 
pl. 52, fig. 7. The upper beds are of sandstone, in which are contained 
the erect stems; beneath this is a deposit of argillaceous iron-stone, resting, 
on a bed of shale ; the whole lies above the coal bed. Similar phenomena 
are found in various other coal mines. 
Secondary Middle Series. 
This follows immediately after the carboniferous system, and is 
covered by the tertiary middle. Crystalline masses are here in but 
slight amount, and stand in decided connexion with abnormal forma- 
tions. Clay, marl, lime, and sandstone masses here attain a high degree 
of development. They frequently alternate with each other, and occur 
in all modifications. Single coarse conglomerates present themselves 
only in restricted localities. The clay, lime, and marl masses are 
generally colored by carbonaceous matter, although sometimes they are 
of a pure white. Coal is of rare occurrence, as also is that of metallic 
minerals. Veins are sparingly distributed, and hardly worth following up ; 
karstenite or anhydrite, gypsum, and rock salt, are of more importance. 
The secondary middle series or Floetz is very rich in fossil remains, these 
occurring both in vast numbers of individuals and of species. Forms of the 
animal kingdom exhibit a great preponderance over the vegetable. The 
former are principally aquatic, as mollusca, fishes, and reptiles, the latter of 
colossal size and wonderful forms. Among the few plants dicotyledons are 
of decided occurrence. 
The Floetz generally occupies low levels, with strata more or less 
horizontal, and is divided into four formations. It has the most extended 
distribution of all the members of the middle series. 
Copper-slate formation (Permian System. Peneian System. Magnesian 
Limestone). This, according to Elie de Beaumont, likewise belongs to the 
palzozoic rocks, and embraces the red sandstone, the zechstein, and the 
rauhkalk. Ihe principal rock species consist of various conglomerates and 
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