formation, there is, at least, great probability that these deposits belong to the same period, and that the whole regio Fucoidarum is to be regarded as a representative of the lower part of the Cambrian system. If that be not admitted, it must be supposed that the regio Fucoidarum has no equivalent in England, and that Sweden is deficient of every deposit from the earlier Cambrian period. For such a supposition, however, no sufficient reason can be afforded. The occurrence of plant-remains cannot be regarded as such, at least so long as nothing corresponding has been known from the Upper Cambrian, and Brachiopods have now been found also in the Longmynd formation. As even the Longmynd formation is said to contain one or perhaps more Brachiopods common to the Lingula-flags,' the break between these formations cannot be very considerable, and we have thus additional reason to give to the Cambrian period a longer duration than Sir R. Murchison has assumed. This circumstance and the great dissimilarity between the faunas of the Upper and Lower Lingula-flags has induced some English writers to refer to the Lower Cambrian system not only the Longmynd group, but also the Lower Lingula-flags. Accordingly the regio Conocorypharum should also be referred to the Lower Cambrian system. The great geognostical resemblance, however, between the regio Conocorypharum and the regio Olenorum makes it more suitable, if a tripartition of the system (into a lower, a middle, and an upper stage) be not preferred, to refer them both to the upper division, at least till some closer palæontological relation, than any hitherto shown, shall have been discovered between the former and the regio Fucoidarum, or between the Lower Lingula-flags and the Longmynd formation. While thus referring, with Sir Charles Lyell, both portions of the "Primordial zone," characterized by Professor Angelin, to the Upper Cambrian system, I still think that the "Tremadoc group" is to be excluded from that System, and, together with its nearest equivalent in Sweden, the regio Ceratopygarum of Professor Angelin, to be regarded as the lowest portion of the Lower Silurian.

2

The sandstone layer of Vestrogothia belongs as a whole to the regio Fucoidarum, but in some other parts of Scandinavia there are deposits of Sandstone also belonging to the younger Cambrian period. Thus in Norway the "Hoejfjelds Kvarts" forms a part of the primordial zone, the stage 2 of Professor Kjerulf.3 In Oeland, at the base of the alum-slate layer, lies a "calcareous quartz-schist" in which the earliest genera of Trilobites have been found, and which by reason of its fossils has been referred by Professor Angelin to his regio Olenorum, but which, with greater show of reason, might be referred to the regio Conocorypharum. In Vestrogothia the same forms occur in the lowest part of the alum-slate, to which the quartz schist of Oeland is thus equivalent.

1 L. c.. p. 2.

? See Th. Belt, On the "Lingula-flags," or "Festiniog Group" of the Dolgelly District. GEOL. MAG. 1867, p. 493 et seq.

Kjerulf, Stenriget og Fjeldlæren, p. 212.

A. Sjögren, Anteckningar om Oeland. Ofversigt af K. Vet. Akad. Förhandl. 1851.

On geognostical as well as upon palæontological grounds two divisions may be distinguished in the sandstone of Vestrogothia. In the lower, which is seldom seen in any natural section, the rock is hard, usually thin-bedded; in the upper, which is in many places exposed and has chiefly given rise to the names of Fucoid sandstone and regio Fucoidarum, it is softer and often thick-bedded. At the very limits of the adjoining layers the sandstone is of an anomalous composition. At the limit of the gneiss it has the appearance of a conglomerate, and contains also some felspar grains. The uppermost sandstone which lies immediately beneath the lowest alum-slate contains a great deal of pyrites, and sometimes, as at Hunneberg, of clay also. These anomalous portions of the layer are very thin, being hardly more than one or two feet in thickness.

The lower parts of the sandstone, although not overlooked by earlier writers, have, owing mainly to the researches of Dr. Wallin and to Professor Torell's descriptions of the fossils collected by the former, attracted a greater degree of attention, and it was through their works that I was led to make myself acquainted with them.

The Lugnås mountain offers the best opportunity of observing the lower division of the sandstone layer and its contact with the underlying gneiss, that is to say, the line of demarcation between the Cambrian and the Laurentian systems. For that reason this locality has often been visited by geologists, but their views respecting the position of the limit are very different. From the olden time millstones have been quarried on a large scale in many places at the foot of the mountain, out of a rock containing the ingredients of granite and gneiss, but in which the felspar has partially been converted into kaolin. According to some writers, this rock is a weathered granite or gneiss, and as such referred to the Laurentian system, or the "fundamental rocks;" others have believed it to be an arkose formed by the mechanical decomposition of a granitic or gneissose rock and the subsequent cementation of the components. According to this opinion it would constitute the lowest portion of the sandstone, and thus belong, together with the overlying sandstone, to the Cambrian (respectively Silurian) system, or the lowest part of the "Transition formation." Hisinger hesitates between these two opinions; sometimes he names the rock a "rotting" granite or gneiss, but sometimes he says that "the millstone bed may be perhaps properly regarded as a granitic transition arkose separated from the fundamental rock or the gneiss by a thin quartzose layer." Sir Roderick Murchison believes the rock to be a Silurian arkose, constituting the lowest part of the sandstone." But Dr. Wallin, in his detailed and accurate description of the layers of the Lugnås mountain," has clearly shown, that the millstone rock is nothing but a variety of the common gneiss of the district, caused by the partial

2

1 Pronounce Lungnose.

2

Anteckningar i Physik och Geognosi, Vol. iv. p. 48, 49 (1828).

3 Anteckningar, Vol. v. p. 67 (1831).

Russia in Europe, etc., vol i. p. 16.* Siluria, 4th ed., p. 347.

Bidrag till kännedomen om Vestgötabergens byggnad. Lund, 1868.

weathering of the felspar, and by no means, as the true arkose, a sandstone-like rock. In visiting the millstone quarries of Lugnås last autumn, I felt convinced, almost at the first glance, of the truth of Dr. Wallin's determination. The mica scales are often seen to be arranged in well-marked laminæ, usually dipping almost vertically, so as to produce a more or less distinct gneissose structure. Besides this the rock (as stated by Dr. Wallin) increases in hardness downwards and resembles more and more the unchanged gneiss of the neighbourhood.

Thus it is above the millstone bed, that the oldest Cambrian deposit commences. The all but horizontal sandstone overlies unconformably the nearly vertical strata of the millstone gneiss. In the quarries its lower division only is exposed. The rock nearest to the gneiss is, as before mentioned, a conglomerate, the sandstone-like cement of which contains larger or smaller rounded fragments of quartz and grains of felspar, the latter sometimes being, as in the millstone gneiss, converted into kaolin powder. In the fourth volume of his "Anteckningar" Hisinger has given a tolerably accurate description of this conglomerate, but he says afterwards, erroneously, that the millstone bed is in immediate contact with a fine-grained sandstone. The conglomerate is usually concreted into one mass with the millstone gneiss, but the limit, as may be expected from the different nature of the rocks, and above all, from their unconformable stratification, is very distinct. As yet no fossils have been found in it.

2

The thin conglomerate is followed, often without any very distinct line of demarcation, by the main mass of the lower sandstone, which is fine-grained, hard, greyish, and reddens in the air. Except in its undermost parts, its layers are very thin. It is interbedded with thin layers of a greenish-grey shale. Sometimes the sandstone, owing to a greater number of lamina of mica, assumes a schistose structure. Hisinger and Sir R. Murchison have already described this sandstone and the shale alternating with it ("bluish-grey clay" Hisinger, "greenish-grey shale" Murchison). Dr. Wallin has not only pointed out all its petrographic characters, but also remarked that it contains peculiar fossils, and for that reason, on the suggestion of Professor Torell, he has termed it "Eophyton sandstone," reserving the name of Fucoid sandstone for the upper and softer parts. It is especially in the deep and numerous quarries on the north-eastern side of the mountain that sections of the Eophyton sandstone are exposed, but the limit next the Fucoid sandstone proper is not exposed there and has not been observed in any other place. The thickness therefore has not been ascertained. Dr. Wallin has found it to be at least 30 feet.

It was in this sandstone that Dr. Wallin during the summer 1867 discovered the Eophyton Linnaanum, Torell, and in the following year he added the Arenicolites spiralis, Torell. Last autumn I visited Lugnås, and collected the fossils I am about to describe. The rock, being very fine-grained, has preserved distinct casts of the 2 Vol. v., p. 67; Vol. vi., p. 60.

1 P. 49.

plants and animals which lived in, or were swept into, the water where it was deposited, so that the most delicate parts can often be distinguished with accuracy. The knowledge, however, to be gained from the materials hitherto obtained is far from being satisfactory, and the interpretations must often be uncertain. Still I have thought it advisable not to delay publishing my observations, as every contribution that may throw some light on so remote a period, can hardly fail to be acceptable.

Arenicolites spiralis, Torell.-The worm described under this name by Professor Torell, at the last meeting of the Scandinavian Naturalists in Christiana, is one of the commonest fossils, especially in the shale. The spirally curled form, which has given rise to the name, is easily recognized and is very constant. Its relations to the numerous burrows which are found along with it are difficult to decide. The thickness of the burrows-almost the only character to be relied upon-is nearly the same as in the spiral form.

Lingula (?) monilifera, n., Plate XI., Figs. 1 and 2.-Of this species, with the exception of a nearly complete and very distinct cast of the outside of the one valve, Pl. XI. Figs. 1 and 2, I found only a few fragments. The inner parts are not visible in any specimen, and the generic determination therefore cannot be settled; but by the size and the general form, and, above all, by the sculpture of the shell the species is easily distinguished from all the Brachiopods with which I am acquainted. In the cast the apex itself is not visible, and one cannot therefore decide whether it is formed by the dorsal or ventral valve. The shell would seem to have been oval and very much depressed, except near the apex, where the sides are more sloping. The length and breadth are about 22 millimetres. The shell is ornamented with extremely close and fine longitudinal, slightly diverging, raised and beaded lines, of which about five may be counted within the breadth of a millimetre. The lines of growth are apparent only near the front margin. Judging from the thickness of the detached slabs in which this species was found, it would seem to have made its appearance in the undermost layer of the Eophyton sandstone, and may thus be considered the earliest Mollusk hitherto known.

In a slab of schistose sandstone I found a Brachiopod which, in the sculpture of the shell, bears some resemblance to the preceding species, but in other respects, as far as one can judge from the indistinct fragments, is widely different. On the surface of the slab lie two shells, of which the margins only are preserved, and even these but incompletely, the middle part being totally effaced. The contour seems to have been almost circular with a diameter of about 50 millimetres. The shell, like that of Lingula monilifera, bears raised, beaded lines, but these lines here seem to be directed towards the centre of the shell; near the circumference their distance from each other is somewhat less than a millimetre. From the general form of the shell this species may most likely be supposed to be a Discina or Trematis.

Eophyton Linnæanum, Torell,' Plate XI. Figs. 3 and 4, and Plate XII.—It is to be hoped that Professor Torell will soon communicate some further observations about this remarkable but as yet not suffi'ciently known species. In the meantime I may venture upon the following remarks. With the materials I have hitherto obtained it is hardly possible to give a full specific description, and I must therefore confine myself to describing separately some of the specimens collected. In Fig. 3 of Plate XI. is shown a piece of sandstone with two specimens lying parallel and close together. The one to the left agrees, as far as I can recollect, with the specimens exhibited by Professor Torell himself, which I had an opportunity of seeing at the last meeting of Scandinavian Naturalists in Christiania. It is a regularly convex fragment of a stem, of equal breadth throughout, and perfectly straight, 170 millimetres long and about 25 millimetres broad, with a height of about six millimetres. Along its whole length it bears a large number of regular furrows, say 35, the breadth of which is nearly the same as that of the intervening raised ribs. Towards the sides both the furrows and ribs are generally somewhat larger, and especially a few millimetres from the margin one broad and deep furrow is to be seen, besides some ribs raised above the others and at nearly regular distances from one another. These higher ribs are for the most part arranged in pairs and separated by a comparatively broad furrow. Such a pair runs along the middle, and several others are more or less discernable on the right side, this arrangement being less conspicuous on the left side. The smaller ribs and furrows running between the larger are exceedingly fine, and it has not therefore been possible to represent them all distinctly enough in the figure, since even in the original they are to be distinguished only with difficulty. All the ribs and furrows are straight except in the uppermost part (a), where those in the middle are gently bent asunder, as though nearly the origin of a branch. On the sides of the stem (b and c) are to be seen awl-like appendages, the organic connexion of which with the stem is somewhat uncertain.

The specimen on the right hand is depressed and mutilated and not visible throughout its whole breadth, which must have been considerable, the preserved portion being more than 25 millimetres broad. The ribs and furrows are much coarser and much less regularly arranged. On the left side they are comparatively equal and small in size, though coarser than in the former specimen. Further to the right hand the breadth of the furrows is much larger, sometimes amounting even to three millimetres. The ribs are several times narrower than the furrows, the coarser among them being often divided. Even in this specimen they are for the most part straight, but near the left margin the outer ones (d) bend outwards, probably where a branch has been given off. Close above this flexion the sculpture is effaced; when the furrows in the upper part again appear, they run quite straight.

1 Bidr. till Sparagmitetagens geogn. och pal., p. 36, t. ii. f. 3, t. iii. f. 1–3. In the figure the inner part of the right side appears more depressed than in the original.