638 Professor Harkness on Coal. 
vegetables growing on the spot, and this may have had its origin in, 
a great measure from the vascular cryptogamic plants which a 
marshy country, such as it might have been, would have produced 
in great abundance, and with a luxuriance of which we can now have 
but little conception, unless we contemplate the profuse vegetation 
of the tropics. The Scotch coal basins, on the contrary, seem to 
have been formed in large inland lakes or hollows, produced by the 
expansion of immense bodies of water. In these lakes or hollows, 
the produce of vast forests, which may have existed in the valleys of 
the high regions, may have been carried down by eddies and currents. 
As these trees had grown at great elevations, most of them carried 
along by the great rivers and their tributary streams, may have con- 
sisted of coniferee, or plants possessing a structure closely allied to 
that of our present pines.”” With respect to these remarks of Mr 
Witham, which tend to the conclusion that coal-seams may have been 
derived from different forms of vegetation, and in which it is inferred 
that the Scotch seams have been the result of drifted plants, the 
latter a circumstance which the nature and arrangement of the seams 
does not support, we have the inference of the existence of a different 
flora under different circumstances during the same time,—a flora 
which may be regarded as occupying the high lands, where conditions 
obtained such as were not favourable to the production of coal. The 
evidence of the existence of this more elevated flora during the 
coal epoch is principally obtained from the sandstone strata of the 
coal measures,—a series of deposits which have had their origin in 
water having a considerable power of transport; and the position of 
the fossil plants which are found in them leads to the conclusion that. 
there had been, in a great measure, different vegetables amongst these. 
plants, or some hard-wooded trees, to which Witham has applied the 
generic term of Pinites, and these seem to have considerable affinity 
to the modern araucaria. These hard-wooded trees appear to enter 
very sparingly into the composition of coal, and their existence dur- 
ing this epoch in no way affects the question as to the nature of the 
plants which constitute the mass of fossil fuel. 
So far as coal affords us evidence in the form of plants which re- 
tain their external aspect, this, for the most part, consists of por- 
tions of sigillarize and nearly allied forms ; and the circumstance that 
the underclays of coal-seams contain such an immense quantity of stig- 
marie, the roots of sigillariz, and kindred plants, supports the in- 
ference that such plants entered largely into the composition of coal. 
—See a recent Memoir published in the Quarterly Journal of the 
Geological Society, vol. x., where Mr Dawson describes in detail the 
measures which make up the coal fields of Nova Scotia, and in these 
coal measures there occur many seams of fossil fuel, which, in almost 
all instances, he attributes to the growth of sigillariz ; and as respects 
conifers, he remarks, that “trunks of this description occur in the 
sandstones both in a carbonized state, and petrified by carbonate of 
