mata; and the appearance of the whole, as it radiated from the central mass, whence the carved trunk proceeded, somewhat resembled that of an enormous coach-wheel divested

of the rim. Unfortunately we cannot yet complete our description of this strange plant. A specimen, traced for about forty feet across a shale bed, was found to bifurcate atop into two great branches,-a characteristic in which, with several others, it differed from most of the tree-ferns, -a class of plants to which Adolphe Brogniart is inclined to deem it related; but no specimen has yet shown the nature of its foliage. I am, however, not a little disposed to believe with Brogniart that it may have borne as leaves some of the supposed ferns of the Coal Measures; nowhere, at least, have I found these lie so thickly, layer above layer, as around the stems of Sigillaria; and the fact that, even in our own times, plants widely differing from the tree-ferns, - such, for instance, as one of the Cycadeæ,- should bear leaves scarce distinguishable from fern fronds, may well reconcile us to an apparent anomaly in the case of an ancient plant such as Sigillaria, whose entire constitution, so far as it has been ascertained, appears to have been anomalous. The sculpturesque character of this richly fretted genus was

Fig. 32.

shared by not a few of its contemporaries. The Ulodendra, with their rectilinear rows of circular scars, and their stems covered with leaf-like carvings, rivalled in effect the ornately relieved torus of a Corinthian column: Favularia, Knorria, Halonia, many of the Calamites, and all the Lepidodendra, exhibited the most delicate sculpturing. In walking among the ruins of this ancient flora, the Paleontologist almost feels as if he had got among the broken fragments of Italian palaces, erected long ages ago, when the architecture of Rome was most ornate, and every moulding was roughened with ornament; and in

he has to dwell on this peculiar feature as one of the most

prominent, and to see, in the multitude of trunks darkened

above by clouds of foliage, that rise upon him in the prospect, the slim columns of an elder Alhambra, roughened with arabesque tracery and exquisite filagree work.

In the Oolitic flora we find a few peculiar features introduced. The Cycadeæ,-a family of plants allied to the ferns on the one hand, and to the conifers on the other, and which in their general aspect not a little resemble stunted palms, appear in this flora for the first time. Its coniferous. genera, too, receive great accessions to their numbers, and

begin to resemble, more closely than at an earlier period, the genera which still continue to exist. The cypresses, the yews, the thujas, the dammaras, all make their earliest appearance in the flora of the Oolite. Among our existing woods there seem to be but two conifers (that attain to the dignity of trees) indigenous to Britain,- the common yew, Taxus baccata, and the common Scotch fir, Pinus sylvestris; and yet we know that the latter alone formed, during the last few centuries, great woods, that darkened for many miles together the now barren moors and bare hill-sides of the Highlands of Scotland,-moors and hill-sides that, though long since divested of their last tree, are still known by their old name of forests. In the times of the Oolite,

on the other hand, Britain had from fourteen to twenty different species of conifers; and its great forests, of whose existence we have direct evidence in the very abundant lignites of the system, must have possessed a richness and variety which our ancient fir woods of the historic or human period could not have possessed. With the Conifers and the Cycades there were many ferns associated,- so many, that they still composed nearly two fifths of the entire flora; and associated with these, though in reduced proportions,

1

EQUISETUM COLUMNARE.

we find the fern allies. The reduction, however, of these last is rather in species than in individuals. The Brora Coal, one of the most considerable Oolitic seams in Europe, seems to have been formed almost exclusively of an equisetum,- E. columnare. In this flora the more equivocal productions of the Coal Measures are represented by what seems to be the last of the Calamites; but it contains no Lepidodendra,-no Ulodendra,-no Sigillaria,-no Favu