I have given illustrations of most of the varieties; some have very few vesicles, in others the vesicles are more abundant. As the colonies are unevenly scattered over broken shells, stems of crinoids, &c., I have been obliged to draw the figures by the eye only, and not by the camera lucida, but the characters of all may be relied upon as being true to nature.

PLATE IV.

Fig. 1. Ascodictyon siluriense, Vine.

This figure is drawn by the aid of the camera lucida from a transparent section of shell, on which the whorls were scattered, so that all the outlines are in proportion, and the fossil is magnified a little over twenty-five times.

Figs. 2-2A. Valkeria tuberoso, Heller.

This species is also drawn by the aid of the camera lucida, and it is magnified about the same, twenty-five times. This is a recent species, dredged by Dr. Pergens, in the Bay of Naples. It is placed here for the purpose of shewing the character of the Zoarium, the whorls of Zoœcia, and the connecting hollow filamentous thread by which the whorls of cells are connected together. The striking similarity between the living and the fossil forms are at once apparent. Fig. 3 and 4. Ascodictyon Youngi, Vine.

Fig. 3 is a magnified fragment of Crinoid stem, on which colonies of this species covered the whole of the surface. On account of the undulations of the stem it is impossible to depict the continuous ramifications of the filaments, hence they appear in the sketch as broken threads. Only one cluster of vesicles is shown, and these and the filaments are magnified to about the same proportions as figs. 1 and 2.

Fig. 4. Two separated clusters of vesicles drawn by the aid of the camera lucida magnified to about 60 diameter. Examples in my own cabinet.

O
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STUDY OF "INTENSE" RAINFALL AT LEEDS, SUNDAY, JULY 19TH, 1891. BY RICHARD REYNOLDS, F.C.S.

(Scale taken from Ordnance Map, 1in. to a mile.)

A violent thunderstorm, lasting not more than 40 min., gave the only rain of the 24 hours. Its maximum fall was at Woodhouse Cliff; in the first 25 min., 23 in. fell; then 15 min. gave 37 in., ceasing sharply. The latter record is at the rate of 1.5 in. per hour.

THE AFFINITY OF DADOXYLON TO CORDAITES.

BY JAS. SPENCER.

There is a large tree-like fossil occasionally found in sandstone. rocks of the Carboniferous formation called Dadoxylon. The affinity of this remarkable plant has been generally supposed to be with the pine family; but recent discoveries have shown that it has more affinity with the Cycadeæ than with the Coniferæ. My paper deals with the various discoveries which have been made in connection with Dadoxylon, more especially with those of recent years. Many of the sandstone rocks of the Carboniferous age abound in fragments of a very curious fossil; occasionally they occur in their natural rounded form, but more frequently they are more or less flattened. They are characterised by having a series of somewhat irregular ringlike markings along the whole length of the stem; more commonly the markings somewhat resemble the rings of a ladder, and many of them are striated longitudinally. For a long time these singular fossils were thought to have been distinct plants, and were named Sternbergia by Artis, in honour of Count Sternberg, one of the founders of the Science of Fossil Botany. At about the same time, or a little before, Sternberg gave them the name of Artisia transversa; but in this country they have generally been known under the name of Sternbergia transversa. In the same sandstone quarries there occur along with Sternbergia transversa, but much more rarely, fragments of another fossil plant of a larger and more tree-like aspect. These specimens generally occur in the form of roundish stems, and of various thicknesses and lengths. When found in situ, in the quarry, they are usually enveloped in a thin layer of smudgy coal, which is probably the mineralized remains of the bark. In many places specimens have been found with portions of their original woody structure well preserved, and microscopic sections of this woody structure show that it closely resembled that of the Pine family. I have come across many specimens of this character in sandstone quarries, but for the purpose of tracing the history of the discoveries

in connection with Dadoxylon it will perhaps be best to begin with those which have been made historical by the discoveries of the late Mr. Witham.

In the year 1826 a large tree trunk, 36 feet in length and 3 feet. in diameter at the base, was discovered in the celebrated Craighleith Quarry, which is situated in the Calciferous Sandstone, a member of the Mountain Limestone series, near Edinburgh. In the year 1830 another large tree 47 feet in length and 5 feet in diameter at the base, tapering to one foot seven inches at the apex, was found in the same quarry. The structure of the wood of these two trees appears to have been identical, and it was named by Lindley and Hutton Pinites Withami after Mr. Witham, who appears to have been the first to study microscopic sections of the wood of fossil plants, and to introduce this most interesting branch of study to the scientific world. The next important discovery took place the year after (1831) in the same quarry, when a small stem with a branch was found; a thin section of the branch showed the annular rings of growth characteristic of the Coniferæ, as well as the pith, which was remarkable on account of its being much larger in proportion to the area of the woody zone than that of recent pines. The authors of the Fossil Flora uamed this specimen Pinites medullaris on account of its large pith. Two years previously a large tree trunk was found at Wide Open, near Newcastle, on the estate of the Rev. R. H. Brandling, in what Mr. Witham terms the Grindstone Post," which was considered to be one of the highest members of the coal formation of that district. The wood of this fossil tree was named by Lindley and Hutton Pinites Brandlingi, after the owner of the quarry. The structure of the wood of all these fossil trees was regarded by Witham as being identical, and therefore they ought to have been named after the first discovered Pinites Withami. It is too late now to remedy the mistake, and the names are useful to denote certain peculiarities in the preservation of the structure and in the form of the pith. Thus Pinites medullaris refers to a very important characteristic feature found in all these supposed Pines, and that is the much larger relative proportion of the pith area than obtains in modern Pines; and the structure of the wood of Pinites Brandlingi

is remarkable for its beautiful state of preservation, and also as being regarded by Prof. Renault and other French Fossil Botanists, as being identical with that of the wood of Cordaites, which they regard as belonging to the Cycadeæ.

The following extract from Witham's work on the "Internal Structure of Fossil Plants," will show that even Witham himself was well aware of some of the differences between Pinites and modern Pines. "These fossil trees," he says, "all present a texture very intimately allied to that of our present Coniferæ, but, as has been shown, differing in certain respects, namely, in most instances the want of concentric rings, and in all cases having reticulations or areoles in two or three series, on two opposite walls of the elongated cellules. In one or two instances the areoles approach very closely to those of the Pines. It is however certain that hitherto no structure precisely resembling that of the Coniferæ in every respect has been found in the Mountain Limestone Series or in the Coal formation."

Endlicher changed the name of the genus from Pinites to Dadoxylon (meaning pine or torch wood) by which it is now generally known, but it is also known under several other names, such as Araucarites, Araucarioxylon, &c., all denoting the resemblance of its woody structure to that of the Araucaria or Norfolk Island Pine, but the term Dadoxylon is preferable, because it leaves the question of its affinities an open one.

It is a singular fact that Dadoxylon does not appear to have grown in the same low-lying localites as the coal producing plants, although it is frequently found with them in the sandstone rocks. and in the shales. After many years of patient research in coal ball material, in which the coal forming plants occur in a beautiful state of preservation, I have not succeeded in finding a single fragment of Dadoxylon. But in the nodules which occur in the marine strata overlying the Hard Bed Coal, the coal in which the coal balls occur, fragments of small stems and branches of Dadoxylon are occasionally met with embedded among marine shells, such as Goniatites, Nautili, Aviculopectens and many other sea shells.

These wood specimens are generally destitute of the bark, but