From the foregoing list it will be seen that all the ten species enumerated belong either to the Upper or Lower Ludlow Rock; but I find that Mr. Salter, so far back as November 1855, was aware of an older species, for he says (Quart. Journ. Geol. Society, Vol. xii., pp. 33 and 34) "the occurrence of body-rings in the Dudley Limestone has been for some time known; and in the Ludlow Museum I lately saw such body-segments connected with the long triple tailspines now known under the name of Leptocheles." And, again, "the carapace and some of the body-joints were found near together by Mr. John Gray of that place (Dudley)." In his paper in the "Annals" (in 1860) already quoted, Mr. Salter observes,-"I believe there are other forms of the genus even in Britain, besides these nine or ten species which have all turned up in the course of a year or two. Abroad still larger specimens have been found in Upper Silurian rocks. M. Barrande has figured the tail-spines of three species, of which Leptocheles Bohemicus has the greatest resemblance to our Ceratiocaris Murchisoni; and a large species, C. Dewii, has been figured as a fish-defence, by Hall, from the Niagara Limestone of New York. Our own Dudley Limestone contains one species; but the metropolis of this curious Silurian 'shrimp' is in the Lower Ludlow Rock, where it keeps company with Pterygoti and other large crustacea.1 It appears not to have been a long-lived genus, for, as yet, none have been detected below the Wenlock Limestone, or above the Upper Ludlow rock." It thus will be seen that Mr. Salter has anticipated the announcement of the occurrence of Ceratiocaris in the Wenlock Limestone, although he does not refer it to any one species. There is little doubt that this is one of the largest British forms of Ceratiocaris, but in the absence of the carapace and body segments, I do not feel justified in adding another species to the burden of palæontological nomenclature. The characters seen in this telson appear to be common alike to C. Murchisoni, C. robustus, and C. Bohemicus. If it must be christened, I would recommend the adoption for it of the name of Sir R. I. Murchison (King of Siluria), as the oldest and best known. Any apparent difference in the specimens figured is due to the difference of condition in which they are preserved-Fig. 9 being only a cast, whilst Fig. 8 still retains its shelly structure. I have not figured the fragment from the Coniston Grit (Lower Wenlock), Helm Knot, Dent, Yorkshire, as it was too small. The specimen from Kirkby Lonsdale (Fig. 9) gives us a new locality, and a fresh horizon, which Mr. Hughes kindly describes. Fragmentary as these remains may appear, yet they nevertheless point to a further extension in time of the genus Ceratiocaris, and may be the means of exciting the search for more perfect specimens. I Not only do we now find spines of Ceratiocaris in the Wenlock Limestone, but numerous portions of Pterygoti have been met with by Messrs. John Gray, C. Ketley, L. P. Capewell, E. Hollier, and other gentlemen, at Dudley, and its vicinity.-H. W. 2 In the second edition of "Siluria," these striated tail-spines are represented in Plate 19, Fig. 1 and 2, from the Uppermost Ludlow Rock, Ludlow, and are there correctly named Ceratiocaris Murchisoni, by Mr. Salter. I V.-NOTE ON THE SILURIAN ROCKS OF CASTERTON LOW FELL, KIRKBY LONSDALE, WESTMORELAND. By THOMAS MCKENNY HUGHES, B.A., F.G.S. SHOULD not have presumed to publish an opinion as to the geological position of the rocks of Casterton Low Fell without having examined the typical region of Coniston and Windermere, had not Mr. Woodward thought it desirable to notice the occurrence there of a species of Ceratiocaris and asked me to furnish him with a note on the bed from which I obtained it. Having therefore collected all the evidence I could in that limited and complicated area, I now, with the permission of the Director of the Survey, send him some extracts from my notes, which may be of interest, as showing the character and relations of the rocks there seen. The Silurian Rocks of Casterton Low Fell, and Barbon Low Fell, are bounded on the West and South by a great fault which brings various parts of the Old Red, Carboniferous, and Permian, against the Silurian Rocks. This may well be seen in Barbon Beck, near the church; where the Old Red is faulted against the Carboniferous Limestone, and this again, in less than fifty yards, is faulted against the Silurian Rocks. The fault runs in a southerly direction bending round to the S.S.W. by Whelprigg, where the Old Red Conglomerate is seen, not in contact with the Silurian, but very close by it. From this point the boundary is entirely obscured by drift till we come to Leck Beck where the Permian beds are thrown against the Silurian. Here again they are not seen in contact, but they occur near one another in such a manner that we cannot explain the phenomena by the unconformity of the Permian on the Silurian. On the East and South East of this the ground is entirely covered by drift, but proceeding up the stream to Bullpot we soon find evidence of a great double fault, like that seen on the other side of the hill in Barbon Beck, running North and South, and bringing the Yoredale Rocks against the Mountain Limestone, and that in a few yards more against the Silurian. These two sets of faults are connected by a series of transverse faults, running nearly W.N.W. and E.S.E. on the South side of Barbon Beck. Thus it will be seen that the Silurian rocks of the area under notice are cut off all round by enormous faults, and therefore that their age must be determined by the evidence we can obtain within that area. I have frequently searched for fossils in company with Mr. Gibbs, Fossil Collector to the Survey, and also with Mr. Hindson, and Mr. Haythornthwaite of Kirkby Lonsdale, but the number, both of species and of individuals, that we were able to obtain, was small. The accompanying section is drawn from the Permian beds in Leck Beck, due North, to beyond the second of the set of faults on the North slope of Barbon Low Fell, about a quarter of a mile South of Barbon Beck. The first beds seen are dark grey coarse flags; the dip is at first irregular, but afterwards tolerably steady in a North-Westerly direction at from 20° to 30°, and this dip prevails with small minor variations all along the ridge. In the lowest beds Graptolites, probably G. priodon, and an Orthoceras, like O. tenuicinctum, occur. Further North we find these flaggy beds succeeded by alternations of a coarse greywacke, 'with joints at right angles to the bedding and a roughly cleaved, distinctly bedded sandstone. All this part of the series I have included under (a), and would estimate its thickness at about 1000 feet. It it succeeded by about 1200 feet of unfossiliferous greywacke (b), with occasional bands of red earthy nodules in the upper part, and alternations of finer sandstone sometimes roughly cleaved. These are succeeded by a set of dark grey shivery sandstones (c), (d) and (e), about 3000 feet thick, with occasional beds of tough greywacke and generally a rough cleavage in the softer beds. Cardiola interrupta occurs all through (c) and (d), but the specimens are not so fine or so numerous in the middle part (d) as in the lower (c). I procured many fine ones from the Fell Road side near where it crosses Eller Beck. In the middle part (d) a very interesting set of fossils occurs, among which the following have been determined by my colleague, Mr. Etheridge: 1 I use the word greywacke merely as a lithological term for the rough, tough, gritty sandstones, so common in the Paleozoic rocks; the term grit being required for the Leck Beck. + Drift. NORTH AND SOUTH SECTION ACROSS CASTERTON LOW FELL AND BARBON LOW FELL. (Length of Section, 3 Miles.) • Permian. a. Dark-gray coarse flags, with alternations of coarse Greywacke and roughly-cleaved, distinctly-bedded Sandstone-about 1000 feet. c. d. e. Dark-grey shivery Sandstones, about 3000 feet thick, with occasional beds of tough Greywacke: fossiliferous. b. Unfossiliferous Greywacke, with red nodules and alternations of finer Sandstones-about 1200 feet. coarse-grained rock intermediate between sandstone and conglomerate, e.g. Millstone grit. and the Ceratiocaris now described by Mr. Woodward. The general character of the rock in the upper part (e) is very similar to that in (c) and (d), but I was unable to procure many fossils except a Graptolite, probably G. priodon, and an Orthoceras, like that found all through the series. On the whole, I find that the lithological character of the rock is very similar throughout, except that at the bottom the tough greywacke passes into dark blue flags, and towards the top there is more of the roughly cleaved dull dark grey sandstone which alternates with the harder beds all through. Prof. Ramsay at once pointed out the general resemblance of these beds to the Denbighshire grits, and the fossils seem to bear out this suggestion. The micaceous flags of Benson Knot, from which the specimens of the carapace of Ceratiocaris in the British Museum were obtained, belong to what are locally called Kirkby Moor Flags-i.e. Upper Ludlow-and are separated from the beds of Casterton Fell by an enormous series, the exact position and thickness of which I shall not be able to determine until I have worked much further north into a clearer country. VI. NOTE ON COAL AND CANNEL. By JNO. ROFE, F.G.S. ALTHOUGH many theories have been suggested to account for the formation of coal-beds, all of which agree in the vegetable origin of the coal itself, none have yet appeared which meet many of the difficulties which surround the subject of their origin, and probably they have been deposited under so many varying conditions that no one supposition would account for the difference in the constituents of the mineral, or for the mode of its formation in different localities. From the Stigmaria found in the underclay, in the great majority of cases, it seems fair to assume that the vegetation from which the coal above it was formed, grew where the coal is found, and there are other reasons for coming to the same conclusion in these cases, but in some places, where the underclay is wanting, this may be doubtful. There can, however, be but little doubt that coal and cannel must have been deposited under different circumstances, and yet in some places they are found interstratified and in contact. This subject was named at the meeting of the British Association at Birmingham, when one of the speakers suggested that the vegetable matter of the cannel was so far decayed as to be reduced to a pulp, like thoroughly rotted peat, which gave the cannel its homogeneous structure, whilst that from which the coal was formed was less de It is, composed, so that coal was more like consolidated lignite. however, difficult to conceive how, in the same bed the vegetable matter could have been first partially decayed, then a layer thoroughly rotted, and then another only partially decomposed; and yet, if this theory be correct, such must have been the case where the two varieties are interstratified, as they are found near Blackrod in the Wigan coal-field. But there is in most, if not in all, cases a well-marked distinction between coal and cannel. Though they both are undoubtedly of vegetable origin, the fossils found in them differ. In the body of the coal itself, what fossils are found are almost, if not entirely, vegetable, whilst in the cannel, at least in that of Lancashire, fishremains not unfrequently occur. Besides this, in the destructive distillation of cannel for gas-making, it is necessary to have the pipes from the retorts much larger than when common coal is employed, because, in the former case, these pipes are very liable to become choked by a deposit, which at first was supposed to be pitch, but which on examination is found to be formed of crystals of chloride of ammonium, agglutinated by tar, from which they may easily be washed out and re-crystallized. May not this large quantity of chloride of ammonium be accounted for by the cannel bed having been deposited in saltwater, the habitat of the fish found in the cannel; the seawater furnishing the chlorine for this salt. I am fully aware that the distillation of common coal gives salts of ammonium, but they are principally carbonate, sulphate, and sulphide with very little chloride, and these are all found in what is technically called the ammoniacal liquor. The cannel also gives these salts in solution in the liquor in addition to the crystals sublimed into the pipes as above stated. There would be nothing very unreasonable in supposing the growth of a rank vegetation in a swamp on the margin of an estuary, sufficient to form a bed of coal; that this, either by subsidence or by the breaking of a bank, became covered by the sea, and from a fresh became a marine swamp like the mangrove swamps of the tropics (under which fish feed), and thus accumulate another stratum under seawater, and probably from a different class of plants, until by some fresh alteration of level or by the acumulation of another bank to exclude the sea, the original state of things was restored and another freshwater deposit is formed. There might then be a bed of cannel between two beds of coal, and that such alterations of levels may take place, or have taken place, can scarcely be doubted by any geologist. It does not appear possible, under the supposition that coal results from transported materials, to account for the interstratification above referred to. Possibly, in some instances, independent beds of cannel may have been derived from a deposit of sea-weed, such as the great weed-bed of the Atlantic. VOL. III-NO. XXIII. 14 |