which present every sign of having been water-rolled and worn smooth by attrition. The pebbles consist of white or smoky quartz, and lie imbedded in a sandy or quartzitic matrix. The older rocks, from the waste of which these conglomerates are derived, were probably members of the Primary Formation, on which the Witwatersrand beds lie. That these older rocks were largely veined with quartz is evident from the nature of the pebbles, and that they were not the source of the gold is evident from the fact that the quartz pebbles do not carry gold, the metallic contents being confined to the matrix.

There is little doubt that the gold was introduced subsequently to the deposition of the beds by means of mineralising solutions, which ascended the planes of disruption and fissuring which resulted from the disturbance of the beds during their upheaval. A considerable amount of basic igneous matter was also introduced, and now appears in the beds in the form of dykes and intrusive sheets.

The angle of dip of the auriferous beds at their outcrop is generally high (50°-80°), but the lowest workings of the mines evidence a considerable flattening of the deposits, the average dip in the lowest levels being at present not more than 30°. It is probable that the flattening will continue, and that the dip in the deep level workings will be found to be not more than 25°. As these deep levels will probably be worked to a vertical depth of 4,000 to 5,000 feet, the zone of workable auriferous deposit must be at least 1 mile wide.

11. Report on the Stonesfield Slate.'-See Reports, p. 414.

12. On the Strata of the Shaft sunk at Stonesfield, Oxon, in 1895.
By EDWIN A. WALFORD, F.G.S.

Since 1860 no continuous section of the upper beds of the Inferior Oolite, and of the limestones intervening between them and the Stonesfield Slate, has been exposed in Oxfordshire. In 1860 but brief record seems to have been made of the character of the beds pierced.

The lower part of the section made by the aid of the British Association in 1894-95 resolves itself readily into three divisions:

1. Compact buff-coloured limestones.

2. Sandstone and sandy limestones with vertical markings and borings.
3. Rubbly coarse-grained oolitic limestone (Clypeus Grit) zone Ammonites
Parkinsoni.

Series 1 extends to the north-west as far as Long Compton, in Warwickshire, and on the north to Sibford in Oxfordshire. Around Chipping Norton it is best developed, but its vertical boundaries are hardly determinable. I take it to represent the Fullonian clays and limestones of the South and South-west of England. Just as at Port-en-Bessin and Caen, in Normandy, we see at one place the argillaceous and argillaceo-calcareous series, and at the other the calcareous and siliceocalcareous series, so also from west to east in England the deposits change from argillaceous to calcareous, and with a poorer fauna.

Series 2, generally underlying the limestones, may be traced as far as Banbury, and has a wide range over Northamptonshire. A bed of Trigonia (T. signata) marks is found around Hook Norton, Chipping Norton, and Long Compton, the lower part of the sandy series, with Ammonites Parkinsoni and remains of marsh plants. The higher sandy limestones are recognised by the presence of long annulated stems of Algae (?), extending also through the Northamptonshire deposits, and characterising the higher beds there. The blue and white sandy limestone of Stonesfield is full of vertical markings of plants-markings which are prominent in every section of the Estuarire' sands of Northamptonshire. The succession of these to the bed with Trigonia signata may be seen in a quarry at Sharpshill, between Brailes and Hook Norton, where a well-marked band of siliceous limestone

with Trigonia signata, Ag., T. Lycetti, Walf, is covered with two feet of shattered siliceous stone pierced with vertical markings. These are the Oxfordshire representatives of the Northamptonshire Estuarine Sands.

So far, then, the Stonesfield section enables us to get a better understanding of the relationships of the Oxfordshire and Northamptonshire Inferior Oolite.

Though the zones of the Northamptonshire Inferior Oolite appear at present to be ill-defined, we may hope in Sharpe's Series D to recognise the representative of the well-known Clypeus grit of West Oxfordshire and the Cotteswolds.

TUESDAY, SEPTEMBER 17.

The following Papers and Reports were read :—

1. The Trial-boring at Stutton. By W. WHITAKER, F.R.S.

This, the first attempt of the Eastern Counties Coal-boring Association, is in the low ground southward of Crepping Hall, and has been successful in reaching the base of the Cretaceous beds at the depth of 994 feet, and in proving that these are at once underlain by a much older rock. The Tertiary and Cretaceous beds passed through are as follows:—

Lower Chalk, with very glauconitic marl at the base (almost a

Beneath this is Paleozoic rock, with a high dip, which has been pierced to the depth of over 200 feet.

The thickness of both Chalk and Gault is slightly less th

there is also a little less of the Tertiary beds.

an at

A full account will be brought before the Geological Society.

Harwich, and

2. The Dip of the Underground Palæozoic Rocks at Ware and at Cheshunt. By JOSEPH FRANCIS, M.Inst.C.E.

Ordered to be printed in extenso.-See Reports, p. 441.

3. On the Importance of extending the Work of the Geological Survey of Great Britain to the Deep-seated Rocks by means of Boring. By F. W. HARMER, F.G.S.

The systematic exploration of the subterranean geology of these islands is equally important from a scientific and a practical point of view. At present our knowledge of the structure of the rocks which torm the foundation of our island home is due either to isolated and occasional borings, such as that of the Ipswich Syndicate in search of coal, or to deep wells sunk by mercantile firms, but the latter do not reach further than is necessary to obtain a supply of water, and the work is generally suspended just where it becomes geologically most interesting. But such a Survey is important practically, because unsuspected sources of wealth may be hidden under our very feet.

It is a mistake to suppose that a discovery such as that of a new coal-field would enrich only the landowners of the district, because whenever any appreciation of real property takes place, the State at once claims its share of the increased

value, both for imperial and local purposes. The average for the whole country of the rates raised by local taxation alone was, for 1891, 3s. 8d. in the £, to which must be added imperial taxes and the tithe. It may be stated roughly, that for every 1001. of yearly unearned increment' the State is benefited in one way or another by 25l., or one-fourth of the amount. The discovery of a new coal-field would cause increased prosperity in the district in which it occurred, and from this the State, through taxation, would derive great though indirect advantage.

The growing difficulty of finding employment for the ever-increasing population of these islands is a strong reason why this Survey should be undertaken.

Part of the cost might be borne by the landowners under whose property any minerals were discovered. Certain districts should be selected with the consent of the Local Authorities, and Parliamentary power taken to charge a royalty on any minerals obtained below a certain depth. Landowners would probably welcome proposals to make borings on their estates on such conditions. In the first instance, however, the Survey should map out accurately the subterranean limits of existing coal-fields, or mineral-bearing rocks, but trial borings should be put down in different localities, and each new boring would help to show more plainly the direction in which further investigations should be made. Much light would be thrown by such a Survey on the circulation of underground waters, a matter of great practical importance.

The expense of boring would be much reduced if undertaken on a large scale, as machinery and apparatus would be available again and again. The Survey would employ its own workmen, who would become increasingly efficient and economical.

4. The Cladodonts of the Upper Devonian of Ohio.
By Professor E. W. CLAYPOLE, D.Sc. (Lond.)

Numerous specimens of the Cladodonts of the Cleveland Shale in Ohio have been found by Dr. William Clark. They for the first time reveal to us the general form of the fishes to which belonged the teeth that have alone so long represented the genus Cladodus. The fossils are in very fair preservation, but their state of pyritisation has obscured many of the details of their structure. So far as regards their form, however, we now know that they were long, slender fishes, resembling in their character the sharks of the present day; that they possessed well-developed and powerful pectoral and caudal, with weak ventral, fins, the dorsals being unknown; that they were for the most part, or altogether, spineless; that at least one species possessed cladadont teeth of more than one pattern; and that they had near the hind end of the body a peculiar flat expansion or membrane of rudely semicircular form, which gave to the caudal extremity when seen from above the outline of a sharp-pointed shovel.

The largest whole specimen yet found shows a fish of about 6 feet in length, but detached teeth and other fragments indicate others of double this size, and supply abundant proof that in late Devonian times, and in the North American area, the elasmobranch fishes had attained very great proportions and a high stage of development.

Hitherto the Cladodonts have been regarded as, in the main, characterising the Lower Carboniferous rocks, but we now find them abounding in the earlier Devonian strata, and, as shown by the contents of their stomachs, preying-in some cases at least on the smaller placoderms of the same area.

From the evidence of the new specimens it appears most likely that the species already defined from single and isolated teeth can no longer be maintained.

For details see the author's papers in the 'American Geologist' for 1893-4-5.

5. The Great Devonian Placoderms of Ohio, with Specimens.
By Professor E. W. CLAYPOLE, D.Sc. (Lond.)

The Upper Devonian Shales of Ohio have recently afforded a remarkable series of fossil fishes rivalling in size and interest those found many years ago in the Old Red Sandstones of similar age in Scotland, and described by Agassiz and Hugh Miller. The earliest of these, Dinichthys, was closely studied, and its structure was well explained by the late Dr. Newberry. It was an immense armour-clad fish whose head measured from 2 to 3 feet in length. Titanichthys, the second of the group, though less massive, was of yet larger size. Gorgonichthys, the third, was described by the present writer in 1893, and, so far as is yet known, was the most formidable of all, possessing jaws of enormous size and thickness, above 24 inches long, ending in teeth or points from 6 to 9 inches in length. The last of the four, Brontichthys, of which a description was also published by the writer in the American Geologist' for 1894, is equally heavy and of equal size, but differs from all the rest in possessing very massive symphysial portions in the mandibles with sockets apparently for the reception of teeth, as in Titanichthys.

Of the two last-named genera only the jaws are yet known with exactness. Other portions have been found of Gorgonichthys, but are still embedded in the matrix. So far as can at present be determined, all the four are closely allied to Coccosteus, and belong to the same family.

The set of casts exhibited in illustration of the fossils have been prepared by their discoverer, Dr. William Clark, and faithfully represent the originals, of many of which only single specimens are yet known. The labour of extricating them from the pyritous shale has proved very heavy, and much yet remains to be done in this direction.

6. Notes on the Phylogeny of the Graptolites. By Prof. H. A. NICHOLSON, M.D., D.Sc., F.G.S., and J. E. MARR, M.A., F.R.S., Sec. G.S.

The authors note that the number of stipes possessed by graptolites has been looked upon as a character of prime importance, many genera being based on the possession of a certain number. Again, the angle of divergence' has been looked upon as an important factor in the diagnosis of families. They are, however, led to believe that a character of essential importance in dealing with the classification of the graptolites, and one which, in all probability, indicates the true line of descent, is found in the shape and structure of the hydrothecæ, the point of next importance as indicating genetic relationship being the angle of divergence.'

These views are illustrated by reference to forms belonging to the 'genera' Bryograptus, Dichograptus, Tetragraptus, and Didymograptus, which appear in turn in this sequence.

Out of nine Tetragrapti (and the authors know of no other forms referred to this genus which are represented by well-preserved examples), eight are closely represented by forms of Didymograptus, which are closely comparable with them as regards characters of hydrothecæ and amount of angle of divergence,' whilst the ninth is comparable with a Didymograptus as regards 'angle of divergence' only. Moreover, four of the Tetragrapti are comparable as regards the two above-named important characters with forms of Dichograptus and Bryograptus with eight or more branches, and the authors confidently predict the discovery of forms belonging to these or closely allied many-branched genera,' agreeing with the remaining Tetragrapti in what they regard as essential characters.

They give details showing the points of agreement of each group of the various series, including a two-branched, a four-branched, and a many-branched form, and point out how difficult it is to understand how the extraordinary resemblances between the various species of Tetragraptus and Didymograptus (to take one example) have arisen, if, as usually supposed, all the species of the genera have descended from a common ancestral form for each genus, in the one case fourbranched, and in the other case two-branched. On the other hand, it is comparatively easy to explain the more or less simultaneous existence of forms possessing

the same number of stipes, but otherwise only distantly related, if they are imagined to be the result of the variation of a number of different ancestral types along similar lines. They allude to similar phenomena which have been shown to exist amongst other organisms; thus Mojsisovics has described analogous cases amongst the Ammonites, and Buckman (under the name of heterogenetic homoeomorphy) amongst the brachiopods, though in this instance the cases of 'species' and not of 'genera' are considered.

Following the above inferences to their legitimate conclusion, the authors point out how 'genera' like Diplograptus and Monograptus may contain representatives of more than one 'family' of graptolites, according to the classification now in vogue, which would account for the great diversity in the characters of the monograptid hydrothecæ.

In conclusion, the authors offer a few theoretical observations upon a possible reason for the changes which they have discussed in the paper.

7. Zonal Divisions of the Carboniferous System.

By E. J. GARWOOD, M.A., F.G.S., and J. E. MARR, M.A., F.R.S.

The authors call attention to previous attempts which have been made to divide the Carboniferous rocks into zones, noting the zonal divisions of the Lower Carboniferous rocks of North England, established by De Koninck and Lohest, and the view expressed by Waagen that fuller work will enable geologists to define a series of zones in the Carboniferous as in older and newer strata.

The detailed work of one of the authors (Mr. Garwood) leads them to suppose that the following zones occur in the Lower Carboniferous beds of the northern part of the Pennine Chain and adjoining regions:-

Mr. Garwood has traced the zone of Productus latissimus, occupying the same relative position to that of P. giganteus, from Settle, in Yorkshire, to the Northumbrian coast, near Howick Burn.

The authors believe that brachiopods and goniatites will furnish good results, if a detailed study of their distribution is made; and they suggest that a Committee be appointed to inquire into the possibility of dividing the Carboniferous rocks into zones, to call the attention of local observers to the desirability of collecting fossils with this view, and, if possible, to retain the services of eminent specialists, to whom these fossils may be submitted.

8. Twelfth Report on Paleozoic Phyllopoda.-See Reports, p. 416.

9. Interim Report on the Eurypterid-bearing Deposits of the Pentland Hills.

10. On some Decapod Crustacea from the Cretaceous Formation of Vancouver's Island, &c. By HENRY WOODWARD, F.R.S.

Through the kindness of Mr. J. F. Whiteaves, F.G.S., Palæontologist to the Geological Survey of Canada, I have lately received a series of Crustacea from Vancouver Island and Queen Charlotte Island, and as they offer a close affinity with forms from our Gault and Greensand, they seem deserving of special notice.