abstracts were received of all but nine; most of the remainder were passed by the sectional committees for reading, but a number of those that were read were not approved by the committees for publication, an example that might be very usefully followed in the case of our British Association. The general character of the meeting was stated to be decidedly scientific, and the discussions to have been carried on with good feeling, and free from personalities; though complaint was made that less sympathy was exhibited on the part of the citizens with the objects of the Association than at any previous meeting. The next meeting will be held at Hartford, Connecticut, on the second Wednesday in August 1874, when a report will be received from a special committee appointed to revise the constitution of the Association with a view to a better carrying out of its objects. The general officers for the meeting will be Dr. J. L. LeConte, president; Prof. C. S. Lyman, vice-president; Dr. A. C. Hamlin, general secretary; and Mr. J. W. Putnam, permanent secretary.

DR. BEKE writes to the Times as follows with respect to Dr. Livingstone :-"If the intelligence from the West Coast of Africa is to be depended on, we may very shortly expect the return of our great traveller, Dr. Livingstone, to his native country On the 1st and 4th inst. you inserted communications from me. to the effect that our countryman was detained a prisoner at a place about 300 miles from Embomma, on the Congo. According to the news brought by the last African Royal mail steamer, it was reported at St. Salvador that Livingstone was then in the interior, about 30 or 40 miles from that place. Now, as St. Salvador is only 80 miles from Embomma, the distance to the latter town from the spot at which, according to the later intelligence, our adventurous countryman was, is not more than 120 miles; and, Embomma being 70 miles from the mouth of the Congo, he would have been within 200 miles of the coast. As the hardy and energetic traveller is not in the habit of letting the grass grow under his feet, he may well be supposed to have come on nearly, if not quite, as quickly as the natives who brought the news of his whereabouts. Consequently, on the assumption that the intelligence received is founded on truth, we may not unreasonably look for the veteran traveller's arrival in England by the next mail steamer from the West Coast of Africa."

WE learn from the Journal of the Society of Arts, that one of the first results in the rise of the price of coal has been the formation of a company in France, whose object is to utilise the power of the ocean tides on the French coast by proper machinery. The first experiment is to be made at St. Malo, where the tide rises nearly 80 ft., and overflows many squarc miles of flats.

DR. GEORGE BURROWS, F.R.S., has been appointed one of the Physicians-in-Ordinary to Her Majesty, in the room of the late Sir Henry Holland.

AT a meeting of the Trustees of the Hunterian Collection of the College of Surgeons, held on Saturday, 8th inst., George Busk, F.R.S., was elected a member of the board, to fill the vacancy occasioned by the death of the Bishop of Winchester.

DR. LYON PLAYFAIR, C. B., F. R. S., M.P. for the Universities of St. Andrews and Edinburgh, has been appointed Postmaster-Ge

neral in succession to Mr. Monsell. Dr. Playfair was a pupil of Liebig, was formerly Professor of Chemistry in the University of Edinburgh, and was at one time Government Inspector-General of Schools and Museums of Science and Art. We hope the new Postmaster-General will endeavour to introduce something like scientific method into the postal department.

THE promoters of the railway tunnel which is intended to cross the Mersey, the shafts for which have already been sunk, have always believed that they would have only a continuous

mass of solid sandstone rock to penetrate. A paper has just been published in the transactions of the Liverpool Geological Society for 1872, by Mr. T. Mellard Reade, C. E., of Liverpool, in which he contends that in all probability a deep gorge, filled up with clay or sand, will be met with, being the (site of an ancient river or torrent formed in or before the times when England was covered with ice, and when its valleys were filled with glaciers. Mr. Reade believes that the ascertained data warrant the hypothesis, that before the boulder clays and other recent strata were laid down, a river draining the land now drained by the Mersey flowed past Runcorn Gap, between land of some considerable elevation, to the sea.

on

We have received, in the form of a neat little pamphlet of 20 pp., price only one penny, an exceedingly interesting lecture "How Flowers are Fertilised," delivered by Mr. A. W, Bennett, F. L.S., at Manchester, on the 5th inst. It is one of a series of Science Lectures for the People, published after delivery by Mr. Heywood of Manchester; they are carefully and neatly printed, and judging from the one before us, purchasers have a very good pennyworth indeed. The enterprise is very creditable to the publisher.

AMONG the papers presented to Parliament, says the Times, relating to the South Sea Islanders, is a report by Captain C. H. Simpson, of Her Majesty's ship Blanche, giving an account of his visit last year to the Solomons and other groups of islands in the Pacific Ocean. While at Isabel Island. Captain Simpson, with a party of officers, went a short distance inland to visit one of the remarkable tree villages peculiar, he believes, to this island. He found the village built on the summit of a rocky mountain rising almost perpendicular to a height of 800 ft. The party ascended by a native path from the interior, and found the extreme summit a mass of enormous rocks standing up like a castle, among which grow the gigantic trees, in the branches of which the houses of the natives are built. The stems of these trees lie perfectly straight and smooth, without a branch, to a height varying from 50 ft. to 150 ft. In the one Captain Simpson ascended the house was just 80 ft. from the ground; one close to it was about 120 ft. The only means of approach to these houses is by a ladder made of a creeper, suspended from a post within the house, and which, of course, can be hauled up at will. The houses are most ingeniously built, and are very firm and strong. Each house will contain from ten to twelve natives, and an ample store of stones is kept, which they throw both with slings and with the hand with great force and precision. At the foot of each of these trees is another hut, in which the family usually reside, the tree-house being only resorted to at night and during times of expected danger. In fact, however, they are never safe from surprise, notwithstanding all their precautions, as the great object in life among the people is to get each other's heads.

THE additions to the Zoological Society's collection during the past week include an Alligator Terrapin (Chelydra serpentina) from North America, presented by the Smithsonian Institution of Washington; a large Hill Mynah (Gracula intermedia) from North India, presented by Rev. T. Main; twelve Gray's Terrapins (Clemmys grayi) from Bussorah, presented by Captain Phillips; a Changeable Tree Frog (Hyla versicolor) from North

America, presented by Prof. Rolleston; a Ground Rat (Aulacodus swinderianus) from West Africa; a Sharp-nosed Badger (Meles leptorhynchus) from China; a Telerang Squirrel (Sciurus bicolor) from the East Indies; two Mantchurian Crossaptions (Crossaptilon mantchuricum) from North China, and two Bluerowned Hanging Parrakeets (Loriculus galgulus) from Malacca, purchased; an Agile Gibbon (Hylobates agilis) from Sumatra, deposited.

SCIENTIFIC SERIALS

THE November number of the Monthly Microscopical Journal commences with a paper by Dr. R. L. Maddox on an organism found in Fresh-pond Water, which he thinks to be new. The accompanying illustration, as well as the description, shows that the monads under consideration are of the simplest structure, and amoeboid in character, of a violet tint, and highly refracting. They vary in size, and contain great numbers of little granular bodies embedded in the gelatinous matrix. The name Pseudoamata violacea is proposed for the new form.-Mr. F. Kitton describes some new species of Diatomacea, including Aulacodiscus superbus from Barbadoes, and others of the genera Stictodiscur, Isthmia, Nitzschia, and Tryblionella.-Mr. Carruthers answers Dr. Dawson's comments on his interpretation of the microscopic appearances of Nematophycus (Carruthers) or Protolaxites (Dawson). As he remarks, the question whether the plant under consideration is a sea-weed or a conifer, is entirely an histological one. Dr. Dawson, in his sections of the fossil found "wood cells, showing spiral fibres and obscure pores; Mr. Carruthers finds "elongated cylindrical cells of two sizes, interwoven irregularly into a felted mass," and the latter observer substantiates the correctness of his observations and his drawings, which prove the accuracy of his views as to the affinities of the plant.-Mr. J. J. Woodward explains the optical principles involved in the construction of Mr. Tolles' new immersion objective that has caused the contest between him and Mr. Wenham.-Dr. Braithwaite continues his description of bog mosses, treating of figuring Sphagnum rigidum and S. molle. This paper is followed by one on the investigation of Microscopic Forms by means of the images which they furnish of external objects, by Prof. O. N. Rood, of Troy, N. Y., which gives an extremely ingenious and simple method of testing with certainty, when the refractive indices of the body examined and the fluid in which it is immersed, are known, of determining whether markings, as of Coscinodiscus triceratium, are depressions or elevations; by regarding the object as part of the optical system, and thence finding whether its influence is that of a convex or concave lense.

SOCIETIES AND ACADEMIES

LONDON

Geological Society, Nov. 5.-Prof. Ramsay, F.R.S., vicepresident, in the chair.-The following communications were read :-"On the Skull of a species of Halitherium from the Red Crag of Suffolk," by Prof. W. H. Flower, F.R.S. A description of this has been already given in NATURE, at p. 13 of the present volume.-"New Facts bearing on the Inquiry concerning Forms intermediate between Birds and Reptiles," by Henry Woodward, F.R.S. The author, after giving a brief sketch of the Sauropsida, and referring especially to those points in which the Pterosaurians approach and differ from birds, spoke of the fossil birds and land reptiles which he considered to link together more closely the Sauropsida as a class. The most remarkable recent discoveries of fossil birds are :-(I.) Archeopteryx macrura (Owen), (II.) Ichthyornis dispar (Marsh), (III.) Odontopteryx toliapica (Owen). The author then referred to the Dinosauria, some of which he considered to present points of structure tending towards the so-called wingless birds. (I.) Compsognathus longipes (A. Wagner), from the Oolite of Solenhofen. (II) The huge carnivorous Megalosaurus, ranging from the Lias to the Wealden. The author next drew attention to the Frilled Lizard of Australia, Chlamydosaurus Kingu (Gray), which has its fore limbs very much smaller than the hind limbs, and has been observed not only to sit up occasionally, but to run habitually upon the ground on its hind legs, its fore paws not touching the earth, which upright carriage necessitates special modifications of the sacrum and pelvis bones. The Solenhofen Limestone, in which Pterosauria are frequent, and which has yielded the remains of Archeopteryx and of Compsognathus, has also furnished a slab bearing a bipedal track, resembling what might be produced by Chlamydosaurus or Compsognathus. It shows a median track formed by the tail in being drawn along the ground; on each side of this the hind feet with outspread toes leave their mark, while the fore feet just touch the ground, leaving dot-like impressions nearer the median line. Hence the author thought that while some of the bipedal tracks which are met with from the Trias upwards may be the "spoor" of stru

thious birds, most of them are due to the bipedal progression of the Secondary Rept les." Note on the Astragalus of Iguanodon Mantelli," by J. W. Hulke, F. R.S. The author exhibited and described an astragalus of Iguanodon from the collection of E. P. Wilkins. The bone was believed to be previously unknown. The upper surface presents a form exactly adapted to that of the distal end of the tibia, so that the applied surfaces of the astragalus and tibia must have interlocked in such a manner as to have precluded all motion between them. The author remarked upon the interest attaching to this fact in connection with the question of the relationship between the Dinosauria and Birds.-"Note on a very large Saurian Limb-bone, adapted for progression upon land, from the Kimmeridge Clay of Weymouth, Dorset," by J. W. Hulke, F. R.S. The bone described by the author presents a closer resemblance to the Crocodilian type of humerus than to any other bone, and he regarded it as the left humerus of the animal to which it belonged. The author refers it provisionally to a species of Ceteosaurus, which he proposes to name C. humero-cristatus.—A despatch from Mr. Alfred Biliotti, British Vice-Consul at Rhodes (dated June 16, 1873), communicated by H. M. Secretary of State for Foreign Affairs, and relating to a volcanic outburst in the island of Nissiros, one of the Sporades, in which there existed a volcano supposed to be extinct. Shortly before June 10 new craters opened in this volcano, and from them ashes, stones, and lava were ejected; many fissures, from which hot water flowed, were produced in the mountain, and the island was daily shaken by violent earthquakes.

Royal Astronomical Society, Nov. 14.-Prof. Cayley, president, in the chair. Sir Geo. 'B. Airy, the AstronomerRoyal, explained the general state of the preparations for the transit of Venus. First, as to the selection of stations. He had originally selected five observing-stations, and in making his choice he had endeavoured to keep in mind what other Governanother station in Northern India for the purpose of taking a ments were likely to do. He had been induced to recommend series of photographic observations to be used in conjunction with the photographic records to be obtained at the southern stations. As the French would not support the station which he had selected in the Sandwich Islands, by an expedition to the Marquesas Islands, he had found it necessary to recommend to our own Government that there should be two subsidiary observing stations in the Sandwich Islands. The station which had originally been chosen was Honolooloo, at about the middle of the islands; the new stations were to be Ha-wai-i to the east and an island at the western extremity of the group. The three stations would thus be distributed over a distance of some 300 miles a fact which would greatly add to their chances of fine weather. He had also been considering the propriety of establishing_stations at Christmas Island, at Hurd Island, and in Whisky Bay, but at present they knew little of the chances of anchorage or fine weather at these places. The Challenger was, however, about to visit and survey them. It would then proceed to Australia, whence the results of their investigations would no doubt be telegraphed to England. As to the selection of stations in the extreme south, the Admiralty would have nothing to do with any station where there was no anchorage, and where there were no human beings. Any station which laboured under both disqualifications must undoubtedly be rejected as unsuitable. He felt himself borne out in this determination by the fact that other nations had adopted the same practical view in their selection of stations. The Astronomer Royal then enumerated and pointed out upon a globe the stations which had been selected: 8 American, 5 French, 4 German, 19 Russian, and 8 English, besides the private enterprise of Lord Lindsay. He then proceeded to give a description of the now well-known "black drop," which was sometimes described as being so large as to make Venus appear “pearshaped,” at other times the illegitimate connection between Venus and the limb consisted only of a narrow black strap or band. The Astronomer-Royal had had a working model prepared at Greenwich with a black disc moved by clock-work. The black ligament, or drop, came out as a very marked feature of the contact with the artificial limb. And he hoped that Capt. Tupman would be able, from a discussion of the observations of different observers with different telescopes, to determine in what proportion the phenomenon was due to the aperture of the telescope used, and to what he might call the personal equation of the observer. He then proceeded to explain how when Venus was upon the sun's limb measures are to be made of the

common chord of Venus and the limb, and how these measures are affected by the formation of a "black drop" between the two images. Lord Lindsay then showed some photographs of a model of Venus upon the limb, in which the "black drop" was photographed as a remarkable feature. He pointed out that when the exposure was longest the "black drop" was most marked; and he showed that its size might be greatly reduced by using a stop which only permitted the rays from the central parts of the lenses to reach the plate. Dr. De La Rue said it was quite wonderful to see the amount of preparations which were going forward at Greenwich. It was not right to throw out such insinuations as Mr. Proctor had done about "official obstructiveness." Mr. Proctor's last paper in the Monthly Notices was a disgrace to the Society. In former days such papers never appeared.-A paper was read by Mr. Lassell on the finding of longitude with small instruments.-Mr. Ranyard then read a note upon a remarkable spot observed by Pastorff upon the sun's disc of May 26, 1828. In June 1819 Pastorff ob ved a nebulous spot with a bright nucleus upon the sun, which has since been recognised as being the comet of 1819 projected upon the bright background of the photosphere. The drawing referred to by Mr. Ranyard contained a similar though smaller nebulous marking, with a bright centre. His object in bringing the drawing to the notice of the society was to inquire whether any small comet or known meteoric stream was between the earth and the sun on May 26, 1828.

Anthropological Institute, Nov. 11.-Prof. Busk, F. R.S., president, in the chair.-Mr. T. J. Hutchinson, F.R.G. S., H.M.'s consul at Callao, read a paper on "Explorations amongst ancient burial grounds, chiefly on the sea-coast valleys, of Peru," Part I. The object of the paper was to describe the "huacas" or burial-grounds, especially those lying beweent Arica and the Huatica Valley, and to expose some popular errors respecting them. Every bit of old wall, every heap of gravel, mound of earth, large or small cluster of ancient ruins of any kind is there called a "huaca." The term huaca (Quichua) is synonymous with Quilpa (Aymara) and means "sacred;" the title may therefore be considered as much applicable to the burying-grounds of Ancon, Pasamayo, and other places where there is no elevation above the country, as to those of Pando and Ocharán, large burial mounds in the valley of Huatica. The author proceeded to describe in detail the mode of interment and the various articles discovered. The celebrated Pacha- Cámác was described. Along the whole course of the Huatica Valley-from Callao to Chorillos-a distance of ten miles direct or sixteen miles round by Lima, there is no natural elevation that could be made available as a sub-structure for those colossal burial mounds. He gave at considerable length his reasons for concluding that there was no "Temple of the Sun" and House of the Virgins" of the Inca religion, and that every huaca was not a "Huaca de los Incas."-Dr. Simms, of New York, gave a most interesting and instructive communication on a flattened skull from Mameluke Island, Columbia River, and described minutely the practice of flattening the head in infancy. In reply to questions put to him, he said that the flattening does not seem to cause pain; that males and females are treated alike, although it had been supposed only males were so treated; that flattening is not apparently transmitted from parents to children; and that, judging from the general intelligence of the native Indians, the practice does not seem in any way to affect the brain or injure the health of the people.

no

MANCHESTER

W.

Mr.

Literary and Philosophical Society, October 7.-Edward Schunck, F.R.S., vice-president, in the chair. Boyd Dawkins, F.R.S., exhibited a fragment of a post struck by lightning on June 2, 1873. It was completely shattered, fragments being driven as far as the walls of the house, twenty-five yards off, and the downward direction of the loose splinters implied that the explosive force was exerted from below upwards, instead of from above downwards. Baxendell thought it was most probably due to the sudden conversion of a portion of the moisture in the post into steam of high tension by the heating action of the electrical discharge, and mentioned instances in which condensed vapour was said to have been seen rising from trees immediately after they had been struck by lightning." On the Relative Work spent in Friction in giving Rotation to shot from Guns rifled with an increasing, and a uniform twist," by Osborne Reynolds, M.A., Professor of Engineering, Owens College, Manchester, and Fellow of Queen's

College, Cambridge. The object of this paper was to show that the friction between the studs and the grooves necessary to give rotation to the shot consumes more work with an increasing than with a uniform twist; and that in the case of grooves which develop into parabolas, such as those used in the Woolwich guns, the waste from this cause is double what it would be if the twist was uniform. The following conclusions were arrived at by Prof. Reynolds :

1. That when the pressure of the powder is constant, Work spent in friction with parabolic grooves Work spent in friction with plane grooves

=

32

2. That when the pressure diminishes rapidly the above ratio = 2.

3. That this ratio may have any values between these two, but that it cannot go beyond these limits.

PARIS

Academy of Sciences, November 10.-M. de Quatrefages, president, in the chair.-The following papers were read An examination of the law proposed by Herr Helmholtz for the representation of the action of two elements in a current, by M. J. Bertrand.-Remarks on an historical point in relation to animal heat, by M. Berthelot.-On the foundation of a meteorological observatory at the foot of the peak Du Midi by the Ramond Society, by M. Ch. Sainte-Claire Deville.-An extract from a letter from M. de Lesseps to Lord Granville on the projected Central Asian Railway. In the letter M. de Lesseps argued against the supposed danger of a Russian invasion of India, and expressed a hope that the Viceroy would permit his son and Mr. Stuart to commence their surveys.-On the structure of the teeth of the Helodermata and Ophidians, by M. P. Gervais.-Memoir on the problem of three bodies, by M. E. Mathieu.-Note on magnetism, by M. J. M. Gaugain. This formed the fifth of the author's notes on this subject.-Researches on the absorption of ammonia by saline solutions, by M. Raoult. The author stated that the difference between the coefficient of solubility of this gas in pure water and in saline solutions of the same salt is proportional to the weight of the salt dissolved in a given volume. -On the transpiration of water by plants in air and in carbonic anhydride, by M. A. Barthelémy.-New researches on the upward transport of nourishment by the bark of plants, by M. Faivre. On the development of swellings on the rootlets of the vine, by M. Max. Cornu.-On certain cases of intermittence of the electric current, by M. A. Cazin.-On a process for finding the nodes of a sonorous tube, by M. Bourbouze.-On the presence and estimation of titanium and vanadium in the basalts of Clermont-Ferraud, by M. G. Roussel.-A method of estimating sugar by means of iron, by M. E. Riffard.-Certain facts relating to the development of bony tissue, by M. Ranvier.-On the Femphigus of Pistacia terebinthus compared with the Phyl loxera quercus, by M. Derbès.-On a new kind of fossil Lemur recently found in the Quercy deposits of tricalcic phosphate, by M. Filhol. On the influence of the moon on meteorological phenomena, by M. E. Marchand. —On a method for the determination of the direction and force of the wind; abolition of weathercocks, by M. H. Tarry.

THURSDAY, NOVEMBER 27, 1873

THE SOUTHERN UPLANDS OF SCOTLAND* II.

THE

HE next member of the series of rocks making up the upper Llandeilo series in the Southern Uplands has received from the officers of the Scotch Geological Survey the name of the Lowther group. In its typical area, which is in the N.W. of Dumfriesshire, this group is composed of "fine grey shales and finely laminated felspathic greywackes with occasional grit beds." The estimated thickness of this group amounts to 5,000 feet. It is seen overlying the Haggis rock group in the streams which drain the upper portion of the Lowther hills; with the underlying Haggis Rock group it forms a synclinal trough in which the Lowther hills are contained.

In Wigtonshire the Lowther group rests upon the Dalveen group. The strata here generally correspond with those of Dumfriesshire, but shales are less abundant, and flagstones and grit with shale bands become more developed. In this county, however, the proportion of the fine and coarse rocks of this group varies in different localities. The rocks of the Lowther group in Wigtonshire are best exposed on the shores of the Irish Channel. Here between Morroch Bay and Knockienausk Head, cliffs are seen from 100 to 300 feet high composed of strata often very twisted and broken, belonging to the Lowther group; and in the higher portion of this group, where the flags are well developed, they have been worked for roofing and flooring purposes.

Above the Lowther group, and forming the highest member of the Upper Llandeilo series, as these occur in the Southern Uplands, are strata composed of grey shales with bands of fine-grained blue greywacke and flinty mudstones. Numerous bands of dark anthracitic shales with graptolites interstratify these rocks. These strata, with their associated anthracitic beds, have received the name of the "Upper Black Shale Group." Their estimated thickness is about 3,400 feet. This Upper Black Shale group occurs near the northern limits of the Upper Llandeilo rocks, and is more abundantly developed in Lanarkshire than in Dumfriesshire.

The Upper Black Shale group, in its typical area, has yielded the officers of the Geological Survey a rich grap tolitic fauna, no less than 27 species having been obtained from this series of rocks. These species bear a very close resemblance to such as occur in the Moffat Shales, a horizon much below the Upper Black Shale group in position. Two Brachiopods have also been found in connection with these Upper Black Shales, viz., Siphonotreta micula, a form also occurring in the Moffat Shales, and likewise in the Upper Llandeilo rocks of Wales, especially in the neighbourhood of Builth; and a Discina which has not yet been specially recognised.

The Upper Black Shales group, following the persistent strike of the Upper Llandeilo rocks of the Southern Uplands of Scotland, makes its appearance in Wigtonshire. Two bands of this group lying in a synclinal trough traverse the portion of Wigtonshire contained in Sheet 3. One of these bands is well seen in Morroch Bay, about a

Continued from p. 24.

VOL. IX.-No. 213

mile and a half south-east of Port Patrick. The other appears south-west of Stranraer, and crossing the moors to the north-east, is seen in the bed of the Luce below Cairnarzean. In Morroch Bay the Upper Black Shale group exhibits a threefold petrological nature. The higher beds consist of thin black shales, having in them lenticular masses and seams of coarse clay, ironstone, and nodular layers of greywacke and pyritous kernals. The strata here are much crumpled, and intrusive masses and veins of felstone have invaded them. It is in this upper portion of the group that graptolites occur, but the number of species obtained from these strata is considerably under what have been found in the Upper Black Shale group of

Lanarkshire.

The representatives of the Upper Llandeilo rocks in the Southern Uplands of Scotland attain to a very great thickness. Of the lower portion of the series, the Ardwell group, the Lower or Moffat Black shale group, the Queenberry grit group, the Hartfell group, and the Daer group, the officers of the Geological Survey have not given their thickness in Dumfriesshire. Of the other four groups, the Dalveen, the Haggis Rock, the Lowther and the Upper Black Shales, these have an estimated thickness of 13,000 ft. If to this amount be added the five groups below, we have a development of Upper Llandeilo strata in the south of Scotland which must amount to nearly 20,000 ft. This great thickness of strata much exceeds the same series of rocks developed elsewhere in the British Isles.

The Upper Llandeilo rocks of the Southern Uplands of Scotland have a greater uniformity in their mineral nature than is usually common to the series. Greywacke in the form of shales, sandstones, grit, and conglomerates, having in some of their sub-divisions black shales containing graptolites, constitute this great thickness of sedimentary rocks. There is an absence of limestone strata, only nodules occurring occasionally, and the calcareous flags which are so characteristic of this portion of the Lower Silurian in its typical area Llandeilo, have no representatives in the South of Scotland. The rocks in this district have been originally greyish and reddish muds, grey and purple sands, and pebble-beds, with occasionally dark carbonaceous muds, which may have derived their black colour either from decaying sea-weeds or decomposing Hydrozoa. The presence of carbonate of lime seems to have been very rare in the Upper Llandeilo seas of the areas which are now recognised as the Southern Uplands, during the deposition of their strata, and to this great absence of carbonate of lime we may probably attribute the absence of some of the fossils which are so abundant in Wales in this series of rocks. Graptolites are essentially the characteristic fossils of the Upper Llandeilo of the Southern Uplands. The same species seem to run through whole strata from the Moffat Shales to the highest member of the series, having a range of probably 18,000 ft.; and many of these forms of graptolites are common alike to the Upper Llandeilo rocks of Wales and Scotland.

The case is, however, very different when we come to compare the crustacea of the two regions. In Scotland the Upper Llandeilo crustaceans are very few, and almost confined to Phyllopods, being Peltocaris Harknessi, P. aptychoides, and Disinocaris Brownii, while in Wales we have a considerable development of trilobitic life. Of the

E

latter only one specimen, in the form of a tail, has yet been obtained from the Upper Llandeilo strata of the South of Scotland; and this specimen is too imperfect to admit of its being specifically determined. With reference to molluscs, these are nearly equally rare in the Southern Uplands. Only two Brachiopods have hitherto been recognised, while many forms appertaining to several genera have been obtained from the Welsh Upper Llandeilo strata. Notwithstanding the paucity of varied forms of organic remains in the Upper Llandeilo rocks of the Southern Uplands, their rich graptolitic fauna is at once indicative of their age, and the absence of other forms is most probably referable to want of calcareous strata in connection with these deposits.

The labours of the officers of the Geological Survey among the highly contorted and crumpled rocks of the Southern Uplands have afforded further information, were such required, of the causes from whence cleavage results. In a country so subject to flexures and contortions, where anticlinal axes and synclinal folds have been inverted, we should naturally look for abundant evidence of the superinduced structures from which true slates have derived their origin. The great mass of the Upper Llandeilo rocks of the South of Scotland rarely furnishes anything in the form of slates proper; and when we consider the nature of these rocks, which consist for the most part of greywacke sandstones and grits, we cannot fail to discover that the cause of the general absence of cleavage from these rocks has arisen from their petrological nature. The officers of the Survey have, however, in several instances, pointed out the recurrence of cleavage among the finer shales; and this occurrence usually accompanies violent contortions of the strata.

Although rocks of an Upper Llandeilo age enter so largely into the composition of the Southern Uplands, they are not the exclusive representatives of the Lower Silurian rocks in this area; above the Upper Llandeilo strata rocks referable to the Bala or Caradoc age occur. These Caradoc rocks, which occupy a very small area when contrasted with the Upper Llandeilo strata, are marked in the Southern Uplands by a feature which is unknown to their occurrence elsewhere. They are unconformable to the underlying Upper Llandeilo beds, a circumstance which Prof. Geikie well describes as feature in the geology of Britain." The Caradoc rocks have not been recognised in Wigtonshire. They are described in connection with Sheet 15. They occur in a trough extending from Wedder Dod N.E. at least as far as the hills on the right bank of the Clyde, below Abington in Lanarkshire.

66

a new

Here they are seen as greywackes, "passing on the one hand into a crumbling sandstone, and on the other into pebbly grits, with shale partings and with beds of conglomerate found chiefly at their base." In one spot a little concretionary limestone is seen, "the only example of limestone met with in the Lower Silurian rocks in Sheet 15." This limestone has afforded no fossils, but the conglomerates and the pebbly and gritty beds higher up in the series are abundantly fossiliferous. Denudation has probably removed some higher beds from this group. Its total thickness amounts to about 1,700 feet.

From the Caradoc rocks of the Lead Hills the geological surveyors have obtained a good series of fossils.

We miss from their list the whole of the graptolites so abundant in and so characteristic of the Upper Llandeilo strata. In their place we have corals, trilobites, many forms of brachiopods, two lamellibranchiates, several gasteropods, and an arthorceras. Most of the species are characteristic Caradoc forms; but they have associated with them some which occur also in the Llandovery series. The Southern Uplands of Scotland have other members of the great Silurian series besides those which have been referred to. These occur along a portion of the south-east flanks of the range, and consist of rocks having a general resemblance to the greywacke strata which form so large a part of the Upper Llandeilo rocks in the South of Scotland. The newer Silurian strata occurring on the south-east margin have, however, a very distinct series of fossils; and associated with their shales are found calcareous concretions frequently affording organic remains; the greywackes flaggy beds also in this higher group often contain fossils, especially graptolites. These graptolites belong to species occupying a much higher horizon than the forms which make their appearance in the Upper Llandeilo rocks; and the organic remains derived from the calcareous nodules also indicate strata higher in position than the Caradoc series. The rocks of an Upper Silurian age are well developed on the shores of the Stewarty of Kirkcudbright, especially on the eastern side of the mouth of the Dee. They occur also in Dumfriesshire, being seen near the southern margin of the Silurians at Dalton Mill, in the parish of Dalton, where the flaggy strata yield the same forms of graptolites which occur near the mouth of the Dee; and they have been extensively recognised in Roxburghshire.

As contrasted with the nearest area where Silurian rocks occur in England, the strata and the organic remains of the Southern Uplands of Scotland show great dissimilarity.

The distance of the nearest portion of the area where Silurian rocks are seen in England from the south-east side of the South of Scotland strata of the same series does not exceed 30 miles; for the northern flank of the Caldbeck range in Cumberland is not greater than this, in distance from the axis of the Lower Silurian rocks in Dumfriesshire where the Ardwell group occurs.

The Lake district of the north of England, occupied principally by Silurian rocks, exhibits strata of a lower position than any of the Silurian deposits of the Southern Uplands. These lower rocks of the Lake district are the Skiddaw slates of Prof. Sedgwick, which in many localities contain graptolites.

The facies of this graptolitic fauna is, however, widely different from that of the graptolitic fauna of the Upper Llandeilo rocks of the south of Scotland. In the Lake district there are no strata which can be paralleled with the Upper Llandeilo rocks. Above the Skiddaw slates of the north-west of England there occur great accumulations of igneous rocks in the form of traps, ashes, traptuffs and similar volcanic products. And it is only when the highest of these rocks is reached, which appear to have resulted from sub-aërial volcanic action, that strata occur in which organic remains are met with.

These strata, the Coniston limestones and their associated shales, are prolific in fossils of a nature indicative of the Caradoc age.