the bark was firm and durable. The scales are flat, quite angular and closely appressed, but seem to have been thick, and are evidently free at their extremities and without any indication that they supported leaves. They show no ribs or nervures; but are covered with little subordinate projecting points or scales as shown in the figures. I formerly referred this plant to Knorria, on account of its scaly stem; but this genus has recently been placed in a somewhat equivocal position by Goeppert,* who finding, as I had previously done, that the plants called Knorria in the Lower coal measures, are really decorticated or imperfectly preserved Lepidodendra or Sagenariæ, seems disposed to abandon the genus. The present species might however still remain as a typical Knorria having a scaly stem and quite distinct from Lepidodendron, but to avoid any confusion between it and the plants heretofore known as Knorria but now ascertained to be of a different character, I prefer to place it in the mean time in Selaginites; in the hope that more perfect specimens may soon illustrate more fully its affinities. CONCLUDING REMARKS In comparing with each other the plants of the three localities. above referred to, it will be observed that they have few species in common. Probably 'two species are common to Perry and St. John, and two to the former and Gaspé; while it is doubtful if one is found in all three. It must be observed however that according to Mr. Billings, the fossil shells of the Gaspé sandstones indicate a Lower Devonian age, while it is quite probable that the rocks of Perry and St. John may be Upper Devonian; and this is the more likely as the plants of the St. John beds are decidedly nearer in their facies to those of the coal formation than are those of Gaspé. None of the species found in these old beds have as yet been recognised in the carboniferous system in British America; and only one, C. transitionis, elsewhere. The generic types are however the same, with the exception of Prototaxites and Psilophyton, * Flora der Silurischen, &c., 1860. † Paper on Lower Coal measures, Journal of Geological Society, Vol. XV. P. 69. CAN. NAT. 2 VOL VI. No. 3. and possibly also the form of Cyclopteris represented by C. Jacksoni, which differs from any fern of the coal formation, and is perhaps. entitled as Lesquereux maintains to a distinct generic name. The generic assemblage in the beds now under consideration, resembles that in the lower coal formation, and differs from that in the true coal measures, in the prevalence of Lycopodiaceus plants and the comparative absence of Sigillariæ; but the genera Lepidodendron and Sagenaria so characteristic of the lower coal measures are slenderly represented here. It is also to be observed that the genera Asterophyllites and Sphenophyllum, though common to the St. John group and the coal measures, are, in so far as known, absent from the lower coal formation in Nova Scotia and New Brunswick. The former genus is however found in the Lower coal in Silesia. It is interesting to observe in the St. John beds which have been disturbed and metamorphosed before the carboniferous period, a generic assemblage so similar to that of the coal. On the other hand it is still more curious to find that the absence of the great Sigillaroid and Ulodendroid trees, so characteristic of the wide swampy flats of the coal period, gives to the St. John flora a more modern aspect than that of the coal; though in its exclusively cryptogamous and gymnospermous character, and in its generic forms, it is quite as decidedly palæozoic. In comparing the plants in the Devonian of Eastern America with those of Europe, a smaller proportion of identical species appears than in the case of the coal measures. There may have been in the Devonian period a greater geographical separation or climatic difference between the European and American land than in the time of the coal formation. On the other hand, however, a part of the plants ascertained here belong to the Lower Devonian, which has hitherto afforded only one land species in Europe,while here it contains several well preserved species and even a small bed of coal; and with respect to the Upper Devonian the number of known species is too small as yet to admit of a satisfactory comparison. I trust that the species described in this and my previous paper are but a small instalment of those to be brought to light by further search. In the meantime I present the following summary of these species, as representing the present state of our knowledge. I have introduced those that are doubtful as well as those fully ascertained; and have arranged them in families according to my present views of their affinities-views which may however admit of important modifications when the plants shall become better known. Summary of Fossil Plants, from beds older than the Carboniferous system, in British America and Maine.-[Described in this paper; and in that on the Devonian plants of Gaspé, in the Journal of the Geological Society of London, Vol. 15, and Canadian Naturalist, Vol. 5.] (a).—Exogenous Gymnosperms. (1.) Prototaxites Logani, mihi,.... ........Lower Devonian, Gaspé. (2.) Dadoxylon Ouangondianum, m.,. . . . . . . . . . St. John group. (3.) Sternbergia, (probably pith of last species), Devonian, Perry. (4.) Aporoxylon,... Do. 2. Sigillariæ. (5.) Sigillaria?-Cyperites?..... ....St. John (b.)—Doubtful if Gymnosperms or Cryptogams. .St. John. (8.) Sphenophyllum antiquum, m.,. . . (c.)-Acrogenous Cryptogams. (9.) Lepidodendron Gaspianum, m.,.. (12.) Lycopodites Matthewi, m., (14.) P. robustius, m.,. .Gaspé and Perry. ...Perry. .... Perry. .St. John. Gaspé, Perry, St. John? ...Gaspé. ...Gaspé. ..... Perry. ....St. John. .....St. John and Gaspé. .Devonian, Kettle Point. .Perry and St. John. Adding to the above the species from the Devonian of New York and Pennsylvania, described in the Reports of the Geology of those states, and in the Memoir of Goeppert above referred to, we may estimate the known land flora older than the carboniferous period in Eastern America, at about thirty species, belonging to at least fifteen genera, all cryptogamous or gymnospermous. ARTICLE XI.-On the origin of some Magnesian and Aluminous Rocks. By T. STERRY HUNT, F.R.S., of the Geological Survey of Canada. (Presented to the Natural History Society.) In common with other observers, I have long since called attention to the fact that silicates of lime, magnesia and oxyd of iron are deposited during the evaporation of many natural waters, such as the mineral springs of Varennes and Fitzroy, and the waters of the Ottawa river. I have also suggested that the silicates thus produced may have contributed in a considerable degree to the formation of rocks. (Amer. Jour. Science, March, 1860, p. 284). A hydrous silicate of magnesia which approaches in composition to MgO. SiO3, combined with from ten to twenty per cent of water, and mechanically mixed with small portions of oxyd of iron, alumina, and carbonates of lime and magnesia, forms extensive beds with limestones and clays in tertiary strata, in France, Spain, Morocco, Greece and Turkey. It is the sepiolite of Glocker, the meerschaum of some authors, the magnesite of others. The quincite of Berthier, which occurs in red particles disseminated in limestone, is a similar compound, containing some oxyd of iron. The sepiolite from the basin of Paris occurs beneath the gypsiferous group, and in the lacustrine series known as the St. Ouen limestone, where it forms very fissile shaly layers, enclosing nodules of opal (menilite). The structure of this sepiolite, which I have examined and described as above, and that from Morocco, which is used by the Moors in their baths as a substitute for soap, and has been described by Damour, is peculiar. The mineral is made up of thin soft scales, and when moistened with water, swells up into a pasty mass resembling a finely divided talc. Although agreeing closely with this mineral in the proportions of silica and magnesia, sepiolite contains more water, and both before and after ignition is soluble in acids, which talc is not. We cannot however doubt that talc and steatite have been formed from sepiolite, which has undergone a chemical change and become insoluble. It is possible that serpentine may be derived from another silicate richer in magnesia than sepiolite. The frequent association of carbonates of lime and magnesia with talc, and of carbonate of magnesia, tale and serpentine, as in the ophiolite of Roxbury, would seem opposed to the notion that serpentine may have been formed from the alteration of a mixture of sepiolite and carbonate of magnesia. In ehlorite, which often forms rock masses almost without admixture, we have an alumino-magnesian silicate which cannot have been derived from sepiolite, inasmuch as this contains for the amount of magnesia present, twice as much silica as chlorite. The oxygen ratios of the silica and magnesia in sepiolite are as 3 : 1, and those of silica, alumina and magnesia (including the variable amount of ferrous oxyd which in part replaces the latter) in chlorite are as 6: 3: 5, while in the purest clays the ratio of silica and alumina equals 1 : 1, and in most argillaceous sediments the proportion of silica is still greater. It is evident, therefore, that chlorite could not be formed from a mixture of sepiolite with clay, or even with pure alumina, without the elimination of a large amount of silica, and we are led to regard it as having been generated by the reaction of a silicate of alumina or clay with magnesia, which was probably present in the unaltered sediment in the form of carbonate. Unless indeed the process, which according to Scheerer, has in recent times caused the deposition from waters, of neolite, a hydrous alumino-magnesian silicate approaching to chlorite in composition, be the type of a reaction which formerly generated beds of chlorite, in the same way as those of sepiolite or talc. A silicate of lime allied to sepiolite, has not so far as I am aware, yet been noticed among unaltered sediments, and among crystalline strata calcareous are more rare than magnesian silicates, although double silicates of lime and magnesia (pyroxene and hornblende,) often form beds, and wollastonite, either alone or mingled with carbonate of lime, sometimes constitute rock masses. The double silicates of alumina and lime are however abundant; the lime-feldspars, scapolite, epidote (saussurite), and white garnet, all form beds in crystalline rocks. Reactions in water at the earth's surface, and at no very elevated temperature, may have given rise to double silicates of lime and alumina corresponding to |