The Hawick and Selkirk rocks fill up all the central portion of the district described, extending from near Selkirk to Mosspaul. They form the great anticline of the South Scottish Silurians, and appear to be the lowest rocks exhibited. They contain a few fossils, such as Annelida, Protichnites, Protovirgularia, Phyllopoda.

The Moffat series is remarkable for the bed (or beds) of anthracitic shale which it contains, and which is famous for the large number of Graptolites found in it. The Moffat series, with its black shale-band, makes its appearance twice in the district described,-1st, in the country between Selkirk and Melrose; 2nd, in the region of the Moorfoot Hills; these beds yield fossils of the genera Dicellograpsus, Dicranograpsus, Cladograpsus, Climacograpsus, Discinocaris, Peltocaris, Siphonotreta, Lingula.

The Gala group lies in the syncline formed by these two appearances of the Moffat series, and consists of grits, sandstones, shales, and conglomerates, that imbed a Middle Silurian fauna, including Monograpsus, Diplograpsus, Retiolites, Dictyonema, Aptychopsis, Ceratiocaris, Dictyocaris, Orthoceras.

The Riccarton beds fill up all the Silurian country to the south of a line drawn from Kirkcudbright to Jedburgh. The fossils are Upper Silurian, and include Cyrtograpsus, Ptilograpsus, Theca, Orthoceras, Ceratiocaris, Aptychopsis, Pterygotus, Rhynchonella.

The authors believe that the anthracitic bed of Moffat is of Bala age, that the Gala group contains strata of both Caradoc and Llandovery age, and that the Riccarton beds should be classed with the Wenlock or Lower Ludlow.

On the Graptolites of the Gala Group. By CHARLES LAPWORTH. The Graptolites found in the Gala group form an assemblage quite distinct from that afforded by the Moffat series. The species known at present are :—

Two of these species, i. c. Retiolites obesus and Graptolites socialis, are new to science.

In Retiolites obesus the frond is diprionidian, ensiform, or elongate-elliptical in form, with a length of 1 inch in the largest specimens, to a breadth of more than of an inch. The meshes on the central surface are hexagonal, of an inch in diameter. Round the inner margin of the frond runs a series of large subquadrangular meshes, which forms a peculiar and characteristic braiding, distinguishing this form at once from all other species of the same genus. These meshes show the place of the cellules, which are from 22 to 24 to the inch.

Graptolites socialis is monoprionidian, flagelliform, of an inch in width and less than 2 inches in length. The cellules are formed after the type of those of Graptolites Beckii (Barr.). They are arranged along the concave side of the stipe, from 34 to 44 to the inch.

This species is found in great numbers in some of the Gala beds.

On the Origin of Volcanoes. By P. W. STUART MENTEATH, The author's views are briefly stated in Scientific Opinion' for April 7, 1869. Since that date, M. Fouqué in France, and Peschel in Germany, had published very similar views, although M. Fouqué, until lately, opposed all chemical theories of the origin of volcanoes. The author, therefore, ventured to bring forward his theory more in detail, and he believed that if chemical geology were more gene

rally studied, that theory would not appear startling. He had considered the objections of Bischof and others to chemical theories, and he believed that they did not hit the explanation he proposed. That explanation attributes the force of volcanic action to solar energy, stored up in rocks by buried organic matter-this organic matter either existing in rocks as carbon and carbonaceous compounds, or represented by sulphides and other substances, produced by the reducing-action of organic matter. Volcanoes, as has been said of steam-engines, are worked by "the light of other days." Starting from the five groups of well-preserved extinct volcanoes in Spain and Portugal, proceeding to consider the volcanoes of the Mediterranean basin, and finally volcanoes in general, the author concluded that, as had been pointed out by Sterry Hunt, volcanoes, as a rule, lie on or at the borders of much sedimentary rock; and the exceptions to this rule he considered to be explicable in conformity with his theory. These sedimentary rocks, especially in the Mediterranean basin and under the volcanoes of Catalonia, could be said to contain much organic matter. Next, he examined the alleged fact of the occurrence of volcanoes along great lines of fissure, and concluded that their occurrence in lines was due to their connexion with the sea, as well as with lines of sedimentary deposition. The author believes that the sometimes alleged identity of volcanic rocks was a statement either misleading or meaningless, and that the composition of volcanic rocks was just what we should expect, if they were formed from masses of sedimentary rocks, in presence of seawater. Proceeding to the consideration of the results of Fouqué, Deville, Daubeny, and others, regarding the gaseous products of volcanoes, he showed that these afforded striking evidence that a mixture of gases, similar to that evolved in gasworks, was oxidated in volcanoes with production of great heat. To this heat, and to the burning of separated carbon, sulphur, and probably iron, he attributed the high temperature present in some lava on its appearance in the air. From the researches of Sorby, Zirkel, Daubrée, Delesse, Stoppani, and others on the subject of lavas, he concluded that these were formed at moderate temperatures, and only exceptionally fused by the great heat produced in the crater. The enormous amount of heat assumed to be present in volcanic action was, in the author's opinion, in great part mythical, and what was actually ascertained could be explained by the nature of the substances oxidating in the earth and burning at the crater. As to the introduction of air and water, he referred to the penetration of sea-water at Cephalonia, to the researches of Delesse, to the Catalan trompe, and to the fact that sea-water dissolves much oxygen; while the nitrogen evolved, in volcanic areas and elsewhere, is usually either pure or accompanied by less oxygen than would compose atmospheric air. He then pointed out that the amount of carbon found in rocks might be adequate to produce all the heat required, if we assumed the rocks to have been rapidly deposited; whereas, if they had been slowly deposited, the amount of carbon now existing in them could only be a remaining fraction of that they formerly contained, the rest having been evolved as carbonic acid. If he were to reject geological time, as some have done, he might assume that the volcanic heat to be accounted for was just as much as the average amount of carbon was adequate to supply. After attributing the origin of the vast amount of buried carbon now in rocks to buried carbon in former rocks, and remarking that it must have passed very gradually through the atmosphere, he discussed some correlated processes in nature which would keep volcanic action roughly uniform, the sun-force continually passing through organic matter into volcanic heat. He confined himself chiefly to volcanic action proper, as that was generally considered the best evidence of the original-heat theory; but he considered that such general internal heat as had been ascertained might be attributed to the distribution of volcanic heat by water, to general oxidation of the carbon almost universal in rocks, to friction as shown by Bianconi, and finally, to the electric currents ascertained to exist in the earth, and to be probably produced in great part by the sun.

The paper was illustrated by sketches taken by the writer in the Two Sicilies, the Greek Isles, Catalonia, &c., also by some curious specimens of metamorphosed glass, which he had found while excavating for antiquities in Ischia.

Further Experiments and Remarks on Contortion of Rocks.

By L. C. MIALL.

After recapitulating the results of some experiments on contortion of mountain limestone brought before the Association at Exeter, the author went on to state that with improved apparatus he had extended his experiments to various substances. Limestone appeared to be exceedingly plastic when long subjected to forces of low intensity. Flagstones from the Coal-measures with a certain amount of elasticity possessed little power of permanent deflection. This negative result is, however, to be checked by observation of cases of accidental flexure of flagstones. Examples were cited of these rocks which had yielded to strains, and had become permanently bent. Plaster of Paris the author finds remarkably plastic, and a long series of experiments with dry slabs shows that it can be bent and twisted indefinitely. Slates had also been tested, but with quite inconspicuous results. A considerable elasticity was found to characterize good slate, with a quite inappreciable plasticity. The author had obtained striking examples of artificial contortion by imbedding laminae of various rocks in pitch. These results were applied to the very sharp flexures sometimes seen in hard strata lying in beds of shale. Cases of quite superficial contortion were quoted, and from numerous instances of marked undulations in strata which were underlain by horizontal and undisturbed layers, it was inferred that many contortions extend only to trifling depths. A case of contortion traceable to the removal of part of a hill-side by a landslip was referred to as showing that flexures on a considerable scale may be of quite recent origin. In conclusion, some remarks were made on the general theory of contortions at the surface of the earth.

On the so-called Hyoid plate of the Asterolepis of the Old Red Sandstone. By JOHN MILLER, F.G.S.

In the Number of the Geological Journal' for August 1869, the author published a letter, stating that he had obtained two specimens of the Asterolepis from the great flag-deposits of Caithness, which showed clearly and distinctly that what had hitherto been considered to be the hyoid plate was not a hyoid plate at all, but was in reality the dorsal plate of the Asterolepis, fitting on immediately behind the cranial buckler, pretty much in the same way as the dorsal plate of the Coccosteus fitted on behind its head-plates. He stated that he would endeavour to lay his specimens before the Geological Society of London as soon as possible; however, circumstances have prevented this. The specimens referred to were exhibited on the present occasion, in fulfilment of the pledge given to the Geological Society.

It is right to premise that from the time these plates were first made known to geologists by Asmus and Eichwald in Russia, and by Sir Roderick Murchison and Agassiz in the west of Europe, they have been regarded in Russia and in this country as hyoid plates, down to the period of the publication by Pander of his works on the Devonian system of Russia, in which he stated his opinion that they would turn out to be dorsal plates when more complete fossils turned up. This opinion was shared in by several of our most eminent paleontologists, and amongst others by Mr. Peach, who has long worked in the Astrolepis-beds of Caithness, and is well acquainted with the geology of that county.

In his description of the Asterolepis, Hugh Miller says (Footprints of the Creator,' p. 85 of the edition of 1861):-"That space comprised within the arch of the lower jaws, in which the hyoid-bone and branchiostegous rays of the osseous fishes occur, was filled by a single plate of great size and strength, and of singular form" (ibid. fig. 40).

And again, at p. 87 (ibid.) :-" The two angular terminations of the hyoidal plate (a, a, fig. 40) were received, laterally and posteriorly, into angular grooves in a massive bone of very peculiar shape (fig. 42), of which the tubercled portion (a, a) seems to have swept forwards in the line of the lower jaw." In these short extracts Hugh Miller, with his characteristic unmistakable clearness, states the generally received opinion regarding the position of the so-called hyoid plate; and

it was the author's object to show that the generally received opinion on the subject is a mistake, and that the plate in question is in reality a true dorsal plate, fitting on immediately behind the cranial buckler or head-plates, and that those naturalists who had previously supposed that this would ultimately prove to be its right position, from Pander down to Peach, were found to have been quite correct in their opinion. The author exhibited a sketch of his best specimen, in which was seen the upper surface of the cranial buckler, described by Hugh Miller, with the dorsal plate, in its true position, and attached to the cranial buckler by two "massive bones of very peculiar shape," alluded to in the quotation above.

Conservation of Boulders. By D. MILNE-HOME, F.R.S.E.

Professor Geikie having stated that the next subject to be brought under the notice of the Section was the conservation of remarkable boulders, begged to mention that the Sectional Committee had passed a resolution, intimating their sense of the importance of the subject, and recommending that the British Association should appoint a Committee, with a grant of money at its disposal, to endeavour to discover the position of remarkable boulders in any part of the United Kingdom, and also to have them preserved. The Royal Society of Edinburgh had already taken steps for these objects as regards Scotland; and it would be well to have the movement extended so as to embrace England and Ireland; and the two Committees would no doubt cooperate, as far as Scotland was concerned. He then called on Mr. Milne-Home, the Chairman of the Committee of the Royal Society of Edinburgh, to explain more particularly the objects contemplated, and the measures which might be taken to carry them out.

Mr. Milne-Home said that his attention to the subject had first been awakened by an article in Nature,' from the pen of their President, Professor Geikie, giving an account of proceedings which had been commenced in Switzerland for the preservation of remarkable boulders. Being acquainted with Professor Favre, of Geneva, he had learned from him that the movement embraced Dauphiny and other provinces in the South of France, and that the effect had been to create a strong popular sympathy in the object. Following this precedent, he had induced the Royal Society of Edinburgh to appoint a Committee, whose duty it was to send circulars to all the parishes in Scotland, with the view of ascertaining the existence in them of any boulders remarkable for size or for other features. Many questions of much geological interest could be solved by ascertaining the nature of the rocks composing boulders, and studying their shapes, in order to deduce conclusions as to the transporting agent. These boulders, however, were fast disappearing, sometimes owing to agricultural improvements, and sometimes affording, when broken up, materials for building or for road-metal. It was therefore important to discover the localities where any remarkable boulders existed, in order that they might be examined by those who took an interest in such speculations, and in order also to have them preserved. He had reason to believe that the proprietors and tenants of the lands on which such boulders might be situated would willingly accede to any application which might be made to them by scientific societies to preserve them. He was sure that, were this Section to express views favourable to that object, great good would result.

Further Remarks on the Denudation of the Bath Oolite.
By W. S. MITCHELL.

On Geological Systems and Endemic Disease. By Dr. MOFFAT. The author remarked that the district in which he lived consisted geologically of the Carboniferous and of the New Red or Cheshire sandstone systems; that the inhabitants of the former were engaged in mining and agriculture, and those of the latter in agriculture chiefly. Anemia, with goitre, was very prevalent among those on the Carboniferous system, while it was almost unknown among those of the Cheshire sandstone, and phthisis was also more prevalent among the

former than the latter. As anæmia was a state in which there was a deficiency in the oxide of iron in the blood, he was led to examine chemically the relative composition of wheat grown upon a soil of Cheshire sandstone, carboniferous limestone, millstone grit, and a transition soil between the Cheshire sandstone and the grit; and the analysis showed that wheat grown upon Cheshire sandstone yielded the largest quantity of ash, and that it contained a much larger quantity of phosphoric acid and oxide of iron than that grown upon the other formations. He calculated that a dweller on the Cheshire sandstone who consumed 1 lb. of wheat daily, grown upon the latter formation, took in nearly five grains more per day of oxide of iron than one who dwelt on the Carboniferous system who did the same. The analysis showed also that the wheat grown upon the Carboniferous system was deficient in phosphates or nutritive salts; and one who consumed a pound of Cheshire wheat per day took in nine grains more of phosphoric acid than one who took one pound of wheat grown upon the Carboniferous system. He had endeavoured to ascertain whether the bread of those who dwelt upon the two systems was relatively as deficient in these important nutritive elements as the wheat grown upon them. He had collected twenty samples of bread used by twenty different families living upon each system, and analysis afforded results as conclusive as the examination of the wheat. The deficiency of the nutritive salts in the bread compared with those in the wheat was very remarkable; and it was no doubt owing to the removal of the bran from the flour with which the bread was made. The writer then gave some statistics as to the diseases prevalent in the counties of Chester, Flint, and Denbigh, and stated that the practical deductions to be drawn from the inquiry were, that all young persons living on a Carboniferous formation having symptoms of incipient goitre and anæmia, ought to be moved to a soil upon Red Sandstone, and persons of strumous habit ought to reside upon sandstone at an elevation of at least 800 or 1000 feet above the sea; and that both classes of

persons should live upon food, both animal and farinaceous, which contained the maximum quantity of oxide of iron and the phosphates or nutritive salts. Medical men could not too much impress upon the minds of the public the importance of using flour made from the whole of the wheat, or "whole grain.”

On the Systematic Position of Sivatherium giganteum, Faule. and Caut*. By Dr. JAMES MURIE, F.G.S., F.L.S., &c.

Among the fossil fauna discovered in the Sewalik Hills, the Sivatherium, one of these, as attested by its remains, must have attained the size of a full-grown elephant. It appears, however, to have been a ruminant, in some respects Deerlike, in others more resembling the Antelope. Still stranger, it seems to have had some characteristic features of Pachyderms-the Tapir, for example. After a careful review of the statements and deductions that have been made upon the Sixatherium, the author went on to show that it belonged to those radical forms which by some may be regarded as one of the progenitors of diverse herbivorous groups. The fossil bones studied by him are those contained in the British Museum. There is also a remarkable fragment in the Edinburgh University Museum. The points which he regarded as affording a safe basis of the affinities of this curious animal are:-1. The form and structure of the horns; 2. the shape of the bones of the face; 3. the nature of the teeth; 4. the formation of the basis of the skull; and 5. other peculiarities of the neck, chest, and limb-bones. The Sixatherium, according to him, is unlike all other living ruminants but one, the Prongbuck, from the fact of its having had hollow horns, evidently subject to shedding. It differs thus from Deer, whose solid horns annually drop off, and from the Antelope tribe, Sheep, and Oxen, whose hollow horns are persistent. Save one living form, the Saiga, no recent ruminant possesses, as did the Siratherium, a muzzle resembling in several ways the proboscis of the Tapirs and Elephants. The dentition partook of the characters of the ancient Elasmotherium, &c. The

* This paper has been published in extenso in the Geol. Mag., October 1871, accompanied by two double plates of the restoration of the skeleton and a representation of the animal, d, et juv. Therein references to the several authorities &c. will be found.