entertained of the vegetable nature of some even of the most ancient of these. Many, however, as believed by Professor E. Forbes and Mr. Salter, are certainly referable to the tracks or burrows of marine animals. More recently the Cambrian rocks of Sweden have yielded to the researches of Torell and Linnarsson some remarkable impressions and casts of fossils, which are believed to be of a vegetable nature (GEOL. MAG., September, Vol. VI., p. 393, Plates XI., XII., and XIII.). In Britain there is not, as far as I am aware, any instance of the occurrence of plant-remains in deposits of Lower Silurian age, as to the nature of which all authorities are agreed.1 The Oldhamia of the Cambrian rocks is believed by Mr. Salter to be a plant, but good authorities would place it either amongst the Polyzoa or Hydrozoa. The Cruziana semiplicata of the Lingula Flags has often been assigned to the Fucoids, but it is believed by Mr. Salter to be "the filled-up burrow of a marine worm" (Mem. Geol. Survey, vol. iii., p. 248). Long ago Professor McCoy described from the Skiddaw slates (lowest Llandeilo) certain fossils which he believed to be fucoids (Quart. Journ. Geol. Soc., vol. iv., p. 223, and Pal. Foss., pl. i. A). After studying a large number of specimens, however, I have been compelled to come to the conclusion, held by Mr. Salter and Professor Harkness, that these fossils (viz. Palæochorda major, P. minor, and Chondrites acutangulus) are truly referable to the action of marine worms. Within the last few years, however, I have obtained from the Skiddaw Slates several fossils, which certainly do not admit of being explained in this manner, though I would not go so far as to assert that they are unquestionably plants. The age of the deposit in which they occur renders them, at any rate-whatever their true nature may be of sufficient interest to merit a short description.

Buthotrephis Harknessii, n. sp. (Pl. XVIII., Fig. A). In his Palæontology of New York, Professor Hall describes several species of plants under the generic name Buthotrephis, their range in time extending from the Calciferous Sandstone up to the Clinton Group (Upper Silurian). The characters assigned to the genus are as follows:"Stems sub-cylindric or compressed, branched; branches numerous, divaricating, leaf-like; structure vesicular"? (See Pal. N. York, vol. i., p. 8.) The nature of the fossils described under this head is such as to show clearly that, if not of vegetable origin, they are certainly not referable to the operations of Annelides, Molluscs, or any other animals. This is proved by the fact that they are always more or less regularly branched; and also by their not being simple impressions on the sediment, but by their possessing, on the other hand, a true organic structure, differing in colour and grain from the surrounding matrix, and sometimes even exhibiting a carbonaceous texture.

In the upper beds of the Skiddaw Slates, I have found specimens of a fossil apparently belonging to the genus Buthotrephis, and bearing considerable resemblance to B. gracilis, more especially to the variety 1 With the details of Mr. Hicks's recent discovery of plants in the Cambrian Rocks of St. David's I am not acquainted.

crassa, described by Hall from the Clinton Group (Op. cit. vol. ii., pl. v. fig. 3). The characters, however, of these fossils are so little definite, and the above-mentioned species is so variable, that I have not thought it safe to include our specimens under it, more especially as they exhibit some curious points which are not present in the American form. The fossil in question shows unequivocal organic structure, consisting of dark, nearly black, cylindrical, regularly branching stems, usually about a line in width, which can not be obtained in relief, as they split right through when the shale is laid open. The best specimen which I have found is broken, and consists of a central stem giving off alternately on both sides long secondary branches, which diverge at angles of from 25° to 60°. The terminations of none of these branches are shown, though one attains a length of nearly three inches; nor is any diminution in their diameter observable. The secondary branches in turn bear, at irregular intervals, on both sides, short tertiary offsets, which taper rapidly to a point, and would seem, therefore, to be of the nature of leaves. rather than the bases of fresh branches, though it is not possible to be quite certain of this.

This singular fossil is unquestionably the remains of some organism, and cannot be referred to the action of marine animals of any kind. Its regular mode of branching demonstrates this beyond a doubt. The proofs of its being a vegetable, though less strong, are, I think, sufficiently weighty, more especially as it is difficult to see what else it could possibly be. If it were a Sponge, a Polyzoon, or a Coelenterate of any kind, it would almost infallibly exhibit some structure by which this could be certainly determined, the nature of the sediment being such that the most delicate details-as shewn by the accompanying Graptolites-would be preserved. It is not, however, siliceous, chitinous, or calcareous, and it is merely of a much coarser grain than the enveloping matrix. As to its place in the vegetable kingdom, it were premature, in the absence of perfect specimens, to offer any decided conjecture, though the mode of branching would not lead us to refer it to the Alga. Hall, however, thinks that Buthotrephis is "doubtless allied to the recent Fucus," and it certainly presents some resemblance to the "fucoids" of the lower Ludlow Rock of the neighbourhood of Ludlow.

Loc.-Upper beds of the Skiddaw Slates, Thornship Beck, near Shap.

Buthotrephis (?) radiata, n. sp. (Pl. XVIII. Fig. B.). This fossil occurs only in conjunction with the preceding, and in exactly the same state of preservation, so that there is some reason to think that they are different portions of the same organism. From the contiguity of the two in some specimens-though this, of course, may be accidental -I have been led to think it possible that this form may in reality be the whorled leaves of B. Harknessii, but I have never seen them in direct connection. Its description, however, as a distinct species must be regarded as simply provisional, and I have placed it in the genus Buthotrephis only in view of its probably being a fragment of another form.

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crassa, described by Hall from the Clinton Group (Op. cit. vol. ii., pl. v. fig. 3). The characters, however, of these fossils are so little definite, and the above-mentioned species is so variable, that I have not thought it safe to include our specimens under it, more especially as they exhibit some curious points which are not present in the American form. The fossil in question shows unequivocal organic structure, consisting of dark, nearly black, cylindrical, regularly branching stems, usually about a line in width, which can not be obtained in relief, as they split right through when the shale is laid open. The best specimen which I have found is broken, and consists of a central stem giving off alternately on both sides long secondary branches, which diverge at angles of from 250 to 60°. The terminations of none of these branches are shown, though one attains a length of nearly three inches; nor is any diminution in their diameter observable. The secondary branches in turn bear, at irregular intervals, on both sides, short tertiary offsets, which taper rapidly to a point, and would seem, therefore, to be of the nature of leaves, rather than the bases of fresh branches, though it is not possible to be quite certain of this.

This singular fossil is unquestionably the remains of some organism, and cannot be referred to the action of marine animals of any kind. Its regular mode of branching demonstrates this beyond a doubt. The proofs of its being a vegetable, though less strong, are, I think, sufficiently weighty, more especially as it is difficult to see what else it could possibly be. If it were a Sponge, a Polyzoon, or a Cœlenterate of any kind, it would almost infallibly exhibit some structure by which this could be certainly determined, the nature of the sediment being such that the most delicate details-as shewn by the accompanying Graptolites-would be preserved. It is not, however, siliceous, chitinous, or calcareous, and it is merely of a much coarser grain than the enveloping matrix. As to its place in the vegetable kingdom, it were premature, in the absence of perfect specimens, to offer any decided conjecture, though the mode of branching would not lead us to refer it to the Algæ. Hall, however, thinks that Buthotrephis is "doubtless allied to the recent Fucus," and it certainly presents some resemblance to the "fucoids" of the lower Ludlow Rock of the neighbourhood of Ludlow.

Loc.-Upper beds of the Skiddaw Slates, Thornship Beck, near Shap.

Buthotrephis (?) radiata, n. sp. (Pl. XVIII. Fig. B.).—This fossil occurs only in conjunction with the preceding, and in exactly the same state of preservation, so that there is some reason to think that they are different portions of the same organism. From the contiguity of the two in some specimens-though this, of course, may be accidental -I have been led to think it possible that this form may in reality be the whorled leaves of B. Harknessii, but I have never seen them in direct connection. Its description, however, as a distinct species must be regarded as simply provisional, and I have placed it in the genus Buthotrephis only in view of its probably being a fragment of another form.

B. radiata consists of detached whorls of tapering leaves (?), meeting in a common centre, narrow at their origin, and gradually widening out to terminate in blunt rounded extremities. The size of the whorls varies a good deal, the shape being circular or somewhat elliptical. The number of rays in each whorl varies from ten to twenty-five, their length being from a quarter to more than threequarters of an inch, and their breadth at the extremities being from one-twentieth of an inch to over a line. The colour of the fossil is nearly black, and its texture, like that of the last, is of a much coarser grain than the enveloping matrix.

It is even more difficult than in the case of B. Harknessii to imagine what this can be if not a plant, its form not being that ordinarily assumed by phytoid animals. It seems, however, pretty certain that if its vegetable nature be conceded, it can hardly be referred to the Algæ.

Loc.-Upper beds of the Skiddaw Slates, Thornship Beck, near Shap.

Eophyton (?) palmatum, n. sp. (Pl. XVIII., Fig. c.)-Unlike the two preceding forms, this exhibits no distinct organic structure, but presents itself merely as an impression upon the surface of the stone. The texture of the rock is so coarse that nothing further than the shape of the fossil can be stated. It consists of a central stem, about two lines in width, which gives off alternately on both sides fan-shaped expansions, which are narrow at their origin, but widen out rapidly till a breadth of about three-quarters of an inch may be attained. A similar fan-shaped expansion terminates the stem, and all are marked with numerous sub-parallel or slightly diverging ridges.

Having only a single fragmentary specimen, it is not possible to fix accurately the position of this fossil, but it agrees in its longitudinal furrowing with Eophyton, and may be placed here in the meanwhile. Its characters are, I think, such that it can hardly be ascribed to the action of marine worms, and it is chiefly for this reason that I have been induced to describe it. It also exhibits a much greater affinity to the Algae than does either of the previously described forms.

Loc.-Lower beds of the Skiddaw Slates, Barff, near Keswick.

Chondrites (?) (Pl. XVIII., Fig. D.)-Besides the above I possess a specimen from the Skiddaw Slates which is, probably, referable to the genus Chondrites. I do not describe it, however, as it possibly may belong to the Graptolitida, and its state of preservation is such that this point can not be decided. It consists of a branching and re-branching frond, the branches of which have a uniform width of little less than a line, and terminate in rounded extremities. The branches are flexuous, and are given off alternately in a sub-dichotomous manner. The surface of the specimen is so much discoloured with iron that no details of structure can be made out.

Though larger and less branched, this fossil is not unlike the Chondrites verisimilis of the Ludlow Rocks of the Pentland Hills, which Mr. Salter fully admits to be a true fucoid (Mem. Geol. Survey of Scotland, No. 31, p. 134). As many branched Graptolites, however,

VOL. VI.-NO. LXV.

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