axis of a plant of this genus, from the Coal-field of Nova Scotia, was described as having a transversely laminated pith of the Sternbergia type, a cylinder of woody tissue, scalariform internally and reticulated or discigerous externally, the tissues much resembling those of Cycads. Medullary rays were apparent in this cylinder; and it was traversed by obliquely radiating bundles of scalariform vessels or fibres proceeding to the leaves. Other specimens were adduced to show that the species having this kind of axis had a thick outer bark of elongated or prosenchymatous cells. The author stated that Prof. Williamson had enabled him to examine stems found in the Lancashire Coal-field, of the type of Binney's Sigillaria vascularis, which differed in some important points of structure from his specimens, and that another specimen, externally marked like Sigillaria, had been shown by Mr. Carruthers to be more akin to Lepidodendron in structure. These specimens, as well as the Sigillaria elegans illustrated by Brongniart, probably represented other types of Sigillarioid trees; and it is not improbable that the genus Sigillaria, as usually understood, really includes several distinct generic forms. The author had recognized six generic forms in a previous paper and in his "Acadian Geology;" but the type described in the present paper was that which appeared to predominate in the fossil Sigillarian forests of Nova Scotia, and also in the mineral charcoal of the coal-beds. This was illustrated by descriptions of structures occurring in erect and prostrate Sigillaria, on the surface of Sternbergiacasts, and in the coal itself.

The erect Calamites of the coal formation of Nova Scotia illustrate in a remarkable manner the exterior surface of the stems of these plants, their foliage, their rhizomata, their roots, and their habit of growth. Their affinities were evidently with Equisetaceæ, as Brongniart and others had maintained, and as Carruthers and Schimper had recently illustrated. The internal structure of these plants, as shown by some specimens collected by Mr. Butterworth, of Manchester, and soon to be published by Prof. Williamson, showed that the stems were more advanced in structure than those of modern Equiseta, and enabled the author to explain the various appearances presented by these plants when the external surface is preserved, wholly or in part, and when a cast of the internal cavity alone remains. It was further shown that the leaves of the ordinary Calamites are linear, angular, and transversely wrinkled, and different from those of the Asterophyllites properly so called, though some species, as A. comosus, Lindley, are leaves of Calamites.

The Calamodendra, as described by Cotta, Binney, and others, and further illustrated by specimens from Nova Scotia and by several interesting and undescribed forms in the collection of Prof. Williamson, are similar in general plan of structure to the Calamites, but much more woody plants-and if allied to Equisetaceæ, are greatly more advanced in the structure of the stem than the modern representatives of that order. Specimens in the collection of Prof. Williamson show forms intermediate between Calamites and

Calamodendron, so that possibly both may be included in one family; but much further information on this subject is required. The tissues of the higher Calamodendra are similar to those of Gymnospermous plants. The wood or vascular matter of the thin-walled Calamites consists of multiporous cells or vessels, in such species as have been examined.

In conclusion, a Table was exhibited showing the affinities of Sigillaria, on the one hand, through Clathraria and Syringodendron with Lycopodiaceae, and, on the other hand, through Calamodendron with Equisetacea; while in another direction they presented links of connexion with Cycads and Conifers.

4. "Notes on the Geology of Arisaig, Nova Scotia." By the Rev. D. Honeyman, D.C.L., F.G.S.

The author referred to a previous paper on the Upper Silurian rocks of Nova Scotia, which he stated appeared to him now to be generally repetitions of his Arisaig series. He noticed the occurrence of fossils in one of the beds previously supposed to be almost destitute of organic remains, and described the occurrence, in Arisaig township, of a band of crystalline rocks which appeared to contain Eozoon and were probably of Laurentian age. A note from Prof. Rupert Jones, giving an account of the fossils referred to by Dr. Honeyman, was also read.

May 25th, 1870.-Joseph Prestwich, Esq., F.R.S., President, in the Chair.

The following communications were read :

:

1. "Contributions to a knowledge of the Newer Tertiaries of Suffolk and their Fauna." By E. Ray Lankester, Esq., B.A.

(1) The Suffolk Bone-bed and the Norfolk Stone-bed.-The author pointed out that the recognition of the distinction of these two deposits from the overlying shelly crags was an important step in the determination of the history of these beds. He combated the notion that the Bone-bed and Stone-bed were identical in their contents, and especially dwelt on the differences of the mammalian fauna found in the two. The late Dr. Falconer's views, hitherto prevalent, consisting in regarding the fauna of the Suffolk Bone-bed, Norfolk Stone-bed, and Forest-bed as all of one and the same history and extent, he most strongly opposed. Rhinoceros Schleiermacheri, Tapirus priscus, Hipparion, Hyena antiqua, and a well-defined Miocene Mastodon (Fauna 1) had been found in the Bone-bed below the Suffolk Crag-the first three in some abundance, but never in the Stone-bed or Forest-bed of Norfolk. They belonged to a different fauna from that indicated by the other mammals common to the Bone-bed and Stone-bed (Fauna 2), viz. Mastodon arvernensis, Equus sp., and certain forms of Cervus (studied by Mr. Boyd Dawkins). On the other hand, the Elephas meridionalis (Fauna 3), occurring in the Norfolk Stone-bed and in the Forest-bed, had never

been found in the Suffolk Bone-bed. Mr. Lankester suggested that the association of the first two of these three groups of mammals in Suffolk, and of the second two in Norfolk, might be explained by the hypothesis that they succeeded one another in time, the first (late Miocene) being confined to Suffolk, and dating from before the Diestien period, since he had obtained a Mastodon tooth of the M. tapiroides form enclosed in a Diestien box-stone, the third having existed in Norfolk at a period subsequent to the Coralline Crag, but before the Norwich Crag was deposited, chiefly represented in the lower part of the Forest-bed, but also in the Stone-bed, whilst the second group of mammals had existed in both areas at an intermediate period. Mr. Lankester maintained that this was the explanation suited to the facts as they at present stand, and considered that the question was not one to be shirked. All geological inferences from palæontology rest on what is called negative evidence, and hypotheses must be used in investigation. It was shown that the London clay had contributed very little indeed to the number of mammalian remains found in the Suffolk Bone-bed. Six teeth of Coryphodon and four fragments of Hyracotherium were all that could be found in the various collections.

(2) The Suffolk Box-stones.-These nodules the author had previously described as being the remains of a deposit approximately similar to the Diestien or Black Crag of Antwerp, which had preceded the Coralline Crag in Suffolk. An enlarged list of remains of Mollusca from these nodules was given, and a large series of specimens collected by the author was presented to the Society's Museum. It was from the Diestien beds, containing Conus Dujardinii, Voluta auris-leporis, Isocardia lunulata, &c., that the Cetacean remains of the Suffolk Bone-bed were derived.

(3) A new Ziphioid Cetacean from the Bone-bed of Suffolk.-The rostrum (described in detail) was in the collection of the Ipswich Museum. It indicated a Cetacean of the genus Choneziphius, differing from C. planirostris of Cuvier and C. Cuvieri (of Prof. Owen's recent Monograph) in having a solid projecting apex to the rostrum, and no trace of a bifid structure. Mr. Lankester had recently carefully examined Cuvier's original specimens in Paris, and suggested that possibly Choneziphius planirostris, C. Cuvieri, this, and two other Antwerp specimens are but varieties of one species, according to age and sex. This form, however, was noted as Choneziphius Packardi.

(4) A new Mastodon from the Suffolk Bone-bed.-A Mastodon tooth, enclosed in Diestien matrix, and indicating a form with open and clear valleys, had been obtained by Mr. Baker of Woodbridge, and noticed by the author a year ago. He had since, in various collections, detected eight other fragments of a Mastodon, very distinct from M. arvernensis, and approaching M. tapiroides. Possibly the fragments indicated more than one such distinct species. The condition of these specimens and other evidence tended to associate them with the Rhinoceros Schleiermacheri, Hipparion, &c. forming

a fauna quite distinct from and older than that which was indicated by Mastodon arvernensis.

(5) List of Mammalian Fossils of the Suffolk Bone-bed, with reference to Collections containing them, and Number of Specimens.-The object of this list was to furnish an idea of the actual and relative abundance of the various mammalia, and to afford those interested in the matter information as to the much-scattered materials in private collections.

2. "Notes on an Ancient Boulder-clay of Natal." Sutherland, Surveyor-General of the Colony.

By Dr.

The author described the extensive occurrence in Natal of a formation which he considered to present the essential characters of Mr. Bain's "claystone porphyry." It consisted of a greyish-blue argillaceous matrix, containing fragments of Granite, Gneiss, Greenstone, Clayslate, &c., often of large size, exhibited ripple-markings in some places, and in others showed a rude approach to wavy stratification. It rested generally upon Old Silurian Sandstones, the upper surface of which was often deeply grooved and striated. The author regarded this deposit as an ancient Boulder-clay, perhaps of Permian age.

3. "On the Distribution of Wastdale-Crag Blocks, or Shap-Fell Granite Boulders,' in Westmoreland." By Prof. Robert Harkness, F.R.S., F.G.S.

The author described the position of Wastdale Crag and the general distribution of the blocks of granite derived from it, and discussed the hypotheses which have been proposed to account for this distribution, and especially to explain how the blocks could have been transported to the eastern side of the elevated ground of Stainmoor. The author considered that neither of the extant hypotheses, accounting for the transport of these blocks by the agency of a glacier or of icebergs, was tenable; and he indicated what he regarded as the chief objections to each of them. He suggested that their transport had been effected by the agency of coast-ice, the land being depressed to the extent of about 1500 feet, which would leave the Wastdale Crag sufficiently exposed to atmospheric action to enable it to furnish the blocks; the icefloes, serving as rafts, would suffice to convey the blocks to other parts of the coast, whilst they would not require any great depth of water to float them.

XLVIII. Intelligence and Miscellaneous Articles.

NOTE ON SPIRAL NEBULE. BY T. S. ALDIS, M.A.

THE following are some points connected with nebula which I

have not seen noticed.

The spiral structure can, of course, only be seen when we view a nebula nearly perpendicularly to its plane of rotation.

The nebula we see are selected. All those composed of denser substances have long since compacted into stars. Those which are left are of small density; consequently motion in them will be slow. It may be noticed in passing, that to know the density of a nebula of known shape by the period of an outlying mass, the parallax of the nebula is not needed. At twice the distance, on twice the scale, with the same density the period is not altered.

Now in our own system we have reason to believe* that the planets thrown off the denser nebula (viz. the interior planets) were thrown off in comparatively compact portions; the planets thrown off when the nebula was rare (viz. the exterior planets) were thrown off in crescent-shaped masses or ansæ, extending round some considerable portion of the interior mass. It is in such crescent shapes that we find the outer portions of the nebulæ now seen. The crescent shape, then, of the detached body is probably a further criterion of their low density, confirming our expectation that the motion will be slow and therefore not easily detected.

The spiral formation itself is easily explained. The portion left behind by the contracting nebula is of a crescent shape, the concavity embracing the central mass. As this cools, the interval between the two increases, whilst the outer slowly pursues its now free orbit. If it underwent no further change it would rotate in its periodic time, keeping its concavity constantly towards the central nebula. But it, as well as the nebula, still contracts, and in so doing acquires increased speed of rotation, and thus the foremost cusp will sweep round slowly into the central body, the hinder cusp will sweep out from it. In this way a spiral arrangement of the different detached portions will arise. Of course the foremost cusp, after swinging round a considerable angle, will fall foul of the central mass and be reabsorbed in it, and the hinder cusp, too, will merge in outer masses; so that masses which have rotated considerably will not appear as elongated masses lying across the coils of the spiral, being shorn of their length in the process, and thus the nebula will take its complexion from the coils which are in the earlier stages of development. Manchester Free Grammar School,

October 11, 1870.

* See the paper on the Nebular Hypothesis in the Phil. Mag. Oct. 1869.