es ash 2A Ea aK i oe a si Y) Ne ae 2 iY SS eal a. S, Weeaecne/ L Dee pvers I: - Maree 2 RN pF pitas } i aN :\.. yess Pay ts ~ PEoLIH) Peretti et aye Tm etlt : Fae ss == ae Ras Leh Oe rs ee 0 20%, ACTA ts : I % & wal Mi it % —Ss : = ——1 2 == oe . a We i ¢, 2s 6 RN So hae aes bees = TE ee f ‘ | i x a i i | ' on ee ay Bye aht FESO THE “GEOLOGICAL MAGAZINE NEW SERIES. DECADE VI. VOL. VI. OR VOL. LVI OF WHOLE SERIES. ° JANUARY—DECEMBER, 1919. : we Ws ( A Oi yu" | di = Nie THE GHOLOGICAL MAGAZINE Monthly Journal of Geology. aw Gn Oly OG, Lsi: NOS) DCLV. WO! DCI Vir EDITED BY MANY WOODWARD, iL Do FORSs EGS.) BOR MS. LATE OF THE BRITISH MUSEUM OF NATURAL HISTORY; PRESIDENT OF THE PALAONTOGRAPHICAL SOCIETY ; ETC. AND IR dels UR AULA Ea ASSISTED BY Prorrssor J. W. GREGORY, D.Sc., F.R.S., F.G.8. V8, JBL, TEONINOEL, Ieee INE IOs CE REowesson ds By MARR Sc.D; (Camb:), FR.S., F.G.5:. Siz JETHRO TEALL, Sc.D. (Camb.), LL.D., F.R.S., V.P.G.S. EROnNSSORE Ve We WEAUUES (Sess. TLDs MESe, KIR:S. E-G:s: HENRY WOODS, M.A., F.R.S. De. ARTHUR SMITH WOODWARD, LL.D., F.R.S., F.L.S., WG aS. NW SHRInSs. DECADE Vi, VOL. Vr. VOL. LVI OF WHOLE SERIES. Zcsonian lnstis, i FPO SON JANUARY—DECEMBER, 1919. ‘f ( 24F 636 | Nears LONDON: aloral Muse DULAU & CO., LTD., 34-36 MARGARET STREET, CAVENDISH SQUARE, W.1 1919: STEPHEN AUSTIN AND SONS, LTD. PRINTERS, HERTFORD SOR EATS: PLATE FACING PAGE Dr. Charles Doolittle Walcott : 5 : 5 ‘ 1 II. Paleolithic Flake Implements ; : F . c Behe) III. Pores and Channel-Systems in Megacystis : : : . 115 IV. Lower Cambrian Hyolithide, etc., from Hartshill . : 5 ae V. Slabs of Clay Ironstone from the Highest Coal - measures, Claxheugh, Co. Durham . ! ; : é 3 5 au VI. Adoral Surfaces of Megacystss : : é é é - 262 VII. Section across the Northern and Southern Oil- and Gas-fields of Pennsylvania . : ; : : ; : . 5 ASK) VIII. Neolenus serratus (Rominger), Burgess Shale, C. D. Walcott. . 359 IX. Fossil Myriopod from Rochdale, Lancashire. j : . 411 X. John Hopkinson . a P 2 : 3 ; ‘ . 431 XI. Cryptophyllum Hiberncum, gen. et sp. nov. . : ; . 441 XII. Shell-Limestone Conglomerate at Blackhall Rocks and Jean Jiveson’s Rock . . : : : j é : . 498 XIII. Rock and Spindle Shore Stack East from St. Andrews. Con- centric arrangement of Ash Layers, Rock and Spindle. . . 506 XIV. Bunaia Woodwards, gen. et sp. nov., J. M. Clarke . . . . 5382 XV. Archwocryptolaria skeatsi, Chapman, etc. . . . . . . . 550 St OF nnUSTRATIONS IN TH TEXT Sketch-map of Carboniferous Limestone outcrops near Wellington, Salop 78 Facial suture in Trilobites 104 Diagrammatic section of the atmosphere from the Hquator to the Pole 159 Air rising in the centre of a cyclone 160 Diagrammatic section of termination of Coal-measures, 8. Durham 169 Section showing position of fossiliferous ironstone bands and thrust plane 204 Section at XY in previous Figure 206 Bellinurus Trechmanm, H. Woodw., sp. nov. 210 Kyanite, Sandringham Sands 214 Zircons, Great Gransden 217 Zoned Crystals of Zircon, Great Gransden 218 Crystals of Rutile, Great Gransden . ; : : { ; 9) ele) Map of Drake’s Island, Plymouth 263 Quartz grains, Parish Sand-pit, Aspley Guise 267 Sphene, Aspley Guise 268 Kyanite Crystals, near Woburn 271 Isoseismal lines and disturbed area, Stafford Earthquake . . 302, 304 Harthquake cutting a crust-fold 310 Map showing site of Gravel Plain near Corwen 313 Hydropore-sutures in Megacystis 323 Geological sketch-map of parts of Hritrea and Abyssinia 341 Map showing the outcrops in the Harbertonford area 351 Diagram illustrating arrangements of the coarse fragments in the Crag 353 Sections at Crowdy’s Quarry, New Quarry, and Copse of Austin’s Close . 357 Neolenus serratus (Rominger), by C. D. Walcott . 360 Sketch-map of distribution of Igneous rocks, Strathbogie and Lower Banffshire 365 Tron-ore and basic steel 389 Sketch-map of part of Southern Sikkim 399 View from Badamtam across the Valley of the Ranjit . 401 Map of N. India showing localities connected with Pleistocene glaciation 402 Vill Iist of Illustrations in the Text. North bank of the Great Rangit Valley . d : ; : : “405 Rive segments from the cast of Paleosoma giganteum . F ‘ 5) AKON Reconstructed posterior segments of Paleeosoma giganteum . ; . 408 Paleosoma robustum ; 6 c ; : 3 ; : . 409 Development of major septa in a normal Rugose Coral Q : . 436 Analysis of interambulacral tuberculation in Pyrina and Conulus . . 445 Teeland, after Th. Thoroddsen . : i ; 5 4 . 468 Diagrammatic section across the Bryozoa Reef. : : ‘ . 486 Curve showing number of invertebrate species, Durham Permian . . 488 Diagrammatic section across the Permian outcrop : 0 3 . 489 Diagram to illustrate structure of Rock and Spindle shore stack . . 502 Four diagrams to illustrate the occurrence, proportions, and distribution of silica in Chalk . i : i : c : : 538-44 - No. 655. Decade VI.—Vol. VI.—WNo. I. Price 2s. aa EY . eological Magazine OR Monthly Fournal of Geology. WITH WHICH IS INCORPORATED Hea. GEOLOGIST, EDITED BY HENRY WOODWARD, LL.D., F.B.S. AND R. H. RASTALL, M.A., F.G.S. ASSISTED BY Pror. J. W. GREGORY, D.Sc., F.R.S. | Str JETHRO J. oH. THAL siz Tv. H. HOLLAND, K.C.1 B., D.Sc., F.R.S. PROF. W. W. WATTS, SG.1 Pror. J. E. MARR, Sc.D., F.R.S. Dr. A. SMITH WOOP JANUARY, 1919. | CONTENTS — I. ORIGINAL ARTICLES. Page REVIEWS (continued). Page Eminent Living Geologists: Dr. R. Speight: Buried Forests, New Charles D. Walcott. (With a . ZBERIEW EG lene en teat a iach a ae Oh 39 | Pomtrait. Plate L.) . <.: <<. selneesch>- il The Progress of Mineralogy from III. REPORTS AND PROCEEDINGS. 1864 to 1918. By Dr. G. T. * | Geological Society of London ...... 40 PRIOR, MIAS, FP RAS i282. Gee 10 | Edinburgh Geological Society ...... 49 _A Mines Department for the United Wellington Philosophical Society, TEGHNG{él@ya0) aousaoreb be esseseesaascnannnee 16 Wor Zenllamel 55 Gob sdeobkeceeen one 43 The Interior of the Earth. By | 3 lity 1D)E eae DN stShog WoGresian | lus) IV. CORRESPONDENCE. _ Notes on Ammonites.-—I. By L. F. J.C. Brown....2.-..4 se, 44 SParH, B.Se.4 PGB. cu. 200) De R. F. Scharff od... 46 Il. REVIEWS. Dr. Troedsson: Brachiopod Shales OST eU Ney OVS Carmi cites Wi cuiene is G88 sa. 35 | John Duer Invinge 22).......... ieee 46 Dr. Maury: Santo Domingo Fossils 36 . J. A. Bartrum: Coneretions in VI. MISCELLANEOUS. bus New Zealand Joe ee aOR SAS 38 | Preservation of Meteoric Irons...... 47 Dr. F. H. Hatch: Jurassic Iron- Honorary Deeree of M.A. for SUONES > 9 =. eat eee te Rae aie laee on cee 38 Mr. F, W. Harmer, F.G.S. ...... 48 LONDON: DULAU & OO., Lrp., 34-86 Marcarnr STREET, CAVENDISH SQUARE, W.1. Subscriptions (24s. net) for 1919 are now due; please remit as early as possible to avoid delay in the despatch of the next number. Cloth Cases for Binding may be JAMES SWIFT & SON, Manufacturers of Optical and Scientific Instruments, Contractors to all Scientific Departments of H.M. Home and Colonial and many Foreign Governments. GrandsPrix, Diplomas of Honour, and Gold Medalsat London, Paris, Brussel/s, etc. MICROSCOPES AND OTHER INSTRUMENTS FOR ALL BRANCHES OF GEOLOGY, MINERALOGY, PETROLOGY. Sole Makers of the “DICK”? MINERALOGICAL MICROSCOPES. Dr. A. HUTCHINSON’S UNIVERSAL GONIOMETER. UNIVERSITY OPTICAL WORKS, 381 TOTTENHAM COURT ROAD, LONDON, W.t. Watson's Microscopes for Geology. WATSON & SONS manufacture a special series of Microscopes for Geo- logical work. All have unique features, and every detail of construction has been carefully considered with a view to meeting every requirement of the geologist. Le All Apparatus for Geology supplied. WATSON’S Microscopes are guaranteed for 5 years, but last a lifetime, and they are all BRITISH MADE at BARNET, HERTS. W. WATSON & SONS, Ltd. (ESTABLISHED _1837) 313 HIGH HOLBORN, LONDON, W.C.1. Works:—HIGH BARNET, HERTS. ; Grou. Maa., 1919. Puate I, THE GEOLOGICAL MAGAZINE NEVIISERIES. 0 DECADE Vio VOR. a Vir No. I.—JANUARY, 1919. ORIGINAL ARTICLES. 1.—Eminent Living GeroLoaists. Dr. Cuartes Dootrrrie Watcort, For. Memb. Geol. Soc. Lond., Secretary of the Smithsonian Institution, Washington (D.C.). (WITH A PORTRAIT, PLATE 1.) R. CHARLES DOOLITTLE WALCOTT acquired a taste for geology and natural history when very young. As a schoolboy he made large collections in the region of his home, and determined to follow a scientific career if possible. Descended from New England settlers who emigrated from Shropshire, Dr. Walcott was born in New York Mills, Oneida County, New York (U.S.A.), March 31, 1850. His first American paternal ancestor was Captain Jonathan Walcott, of Salem, Massachusetts, who died in 1699. Ofthe grandfather of Dr. Walcott, Benjamin Stuart Walcott, a writer says’ that he ‘‘moved from Rhode Island in 1822, and became one of the leading manufacturers of central New York; he had broad interests in educational matters, was the founder of a professorship at Hamilton College, and was well known as a philanthropist. His son, Charles Doolittle Walcott, was a man of unusual energy, was well established in business, and held an influential and leading place in the community. Dying at the early age of thirty-four, he left a wife and four children, the youngest, two years old, being the subject of this sketch”’. Dr. Walcott’s early education was in the public schools of Utica, which he entered in 1858, and in the Utica Academy, which he left in 1868. He then entered a hardware store as a clerk and, continuing in such occupation two years, acquired a practical business training, which has proved of great value to him. His scientific tastes were developed at the age of 138, when he became interested in the systematic collecting of fossils and minerals. The following’winter he met Colonel E. Jewett, geologist, paleontologist, and conchologist, from whom he borrowed books and received many suggestions. Geological reading and collecting were continued, and for two winters he devoted much time to optics and astronomy, and incidentally made large collections of insects and birds’ eggs in the spring and summer months. Of this period he says,” referring to fossils accidentally opened u by his wagon wheel when driving: ‘‘In a small drift block o 1 Appleton’s Popular Science Monthly, vol. lii, No. 4, February, 1898, p. 547. 2 Evidences of Primitive Life, Smithsonian Report, 1915 (1916), p. 243. DECADE VI.—VOL. VI.—NO. I. 1 2 Hnuinent Living Geologists—Dr. C. D. Walcott. sandstone which I found in 1867 on the road from Trenton to - Trenton Falls, Oneida County, New York, there is an unusual apparent association of Upper Cambrian (Hoyt limestone) and Ordovician (Aylmer sandstone, Chazy) fossils. When asa boy I found the rounded block of sandstone referred to I broke out all the fossils possible, as at the time I was well acquainted with the Trenton hmestone fauna, and the fossils in the block were strangers to me, with the exception of Leperditia armata. ‘he following winter I endeavoured to locate the stratigraphic position of the associated trilobites, but could not, further than that they were evidently of pre-Trenton age. This study aroused an interest in the American early Paleozoic fossils that gradually ied me to take up the Cambrian rocks and faunas as my special field of research. ‘« As a boy of seventeen I planned to study those older fossiliferous rocks of the North American Continent which the great English geologist Adam Sedgwick had called the Cambrian system on account of his finding them in the Cambrian district of Wales.” In 1871 business took Mr. Walcott to Indianapolis, Indiana, where his scientific tendencies were further stimulated by Professor E. T. Cox, who was then making a geological survey of the Indiana coal- fields. ‘The time now arrived when it seemed necessary to choose between a business life and a life of research. A partnership was offered him on favourable terms, but if accepted little time would remain for study and investigation. Deciding in favour of scientific work, Mr. Walcott left Indiana and returned to New York State. Establishing himself on the farm of William P. Rust, at Trenton Falls, he arranged to do a certain amount of farm-work for his board and lodging, reserving the remainder of his time for study and field- work. Here he remained five years, making a rich collection of unique Trenton limestone fossils, which was sold in 1873 to the Museum of Comparative Zoology of Harvard College. He made an arrangement to go to Cambridge (Massachusetts) and pursue a course of study, under the advice and direction of the great naturalist Louis Agassiz, but this was frustrated by the death of Agassiz. Of this period Dr. Walcott writes:! ‘‘In September, 1873, I said to Professor Louis Agassiz that if opportunity offered I would undertake as one bit of future research work to determine the structure of the trilobite. This promise has kept me at the problem for the past forty-five years, and except for the demands of administrative duties the investigations would have advanced more rapidly. Since 1873 I have examined and studied all the trilobites that were available for evidence bearing on their structure and organization.” In November, 1876, he received his first official appointment, becoming assistant to Professor James Hall, State Geologist of New York, While holding that position researches were made in New York, Ohio, Indiana, and Canada. In July, 1879, Mr. Walcott was appointed field assistant in the United States Geological Survey, then under the direction of Clarence King, and was assigned to the 1 “* Appendages of Trilobites’’: Smithsonian Misc. Coll., vol. lxvii, No. 4, pls. xiv—xlii (in press). Eminent Living Geologists—Dr. C. D. Walcott. 3 study of the great geological section extending from the high plateaus of southern Utah to the bottom of the Grand Canyon of the Colorado. In 1882 he collaborated with Mr. Arnold Hague in the survey of the | Eureka mining district in Nevada and the working out of the great Paleozoic section of central Nevada. The charge of the Palzeozoic paleontology of the Survey was now assigned to him, and though this entailed considerable routine work in the identification of fossils brought from many fields by the various geologists, he was enabled to pursue with vigour his cherished plans for the investigation of the older faunas. He examined the Cambrian formations of the Appalachian belt all the way from Alabama to Quebec, and carried his researches on a more easterly line through New England and New Brunswick to Newfoundland. He also began a series of Western studies which eventually included the most important known bodies of Cambrian and pre-Cambrian rocks in Texas, Arizona, California, Idaho, Nevada, Montana, Wyoming, and South Dakota. In 1888 he was advanced to be paleontologist in charge of invertebrate paleontology in the Geological Survey; in 1891, to be chief paleontologist ; and in 1898, to be geologist in charge of geology and paleontology, in which ‘capacity he had the general direction of that branch of the work of the Survey. In July, 1894, Major J W. Powell retired from the office of director of the Survey, and Mr. Walcott was selected by President Cleveland to succeed him. ‘This position he held until his resignation in 1907 to become Secretary of the Smithsonian Institution, of which he had previously been assistant secretary in charge of the United States National Museum. During those years he reorganized and Mev alnnes the Geological Survey on scientific and business principles. . The confidence reposed in him by the Coneress is attested. by the oe that the initial appropriation of $484, 640 was increased during his administration to several times that amount (¢1,700,000). Between 1902 and 1907 Dr. Walcott directed the organization and conduct of the United States Reclamation Service. He fostered imterest in the forestry movement, and in. 1898 he secured the passage as an amendment to an appropriation for the Geological Survey of the first comprehensive law organizing rie forest reserves of the United States. As the initiator and secretary of the Carnegie istitution of Washington, and its direct administrative officer from 1902 to 1905, and as a member of its Executive Committee from 1902 to the present time (now chairman), he has assisted largely in the suceessful organization and development of the administrative and research work of that Institution. Since 1907, when he was chosen by the Board of Regents as Secretary of the Smithsonian Institution, Dr. Walcott has directed research investigations in various parts of the world, and has personally studied large areas in the Rocky Mountains of British Columbia and Alberta, Canada. The Smithsonian foundation was established by Act of Congress in 1846, under the terms of the will of James Smithson, an Englishman, who in 1826 bequeathed his fortune to the United States of America ‘‘to found, at Washington, 4 Eminent Living Geologists—Dr. C. D. Walcott. under the name of the Smithsonian Institution, an establishment for the increase and diffusion of knowledge among men’’. It was under _ the direction of the Smithsonian Institution that Colonel Theodore Roosevelt (1909-10) made his memorable African expedition, being accompanied by representatives of the Institution and its branches. The administration of the Smithsonian Institution includes the Unites States National Museum, International Exchanges, Bureau of American Ethnology, National Zoological Park, Astrophysical Observatory, and International Catalogue of Scientific Literature, besides the Aerodynamical Laboratory and the National Gallery of Art. Dr. Walcott is especially known as a student of the Lower Paleozoic (Cambrian) and pre-Paleozoic (Algonkian) sedimentary formations and included organic remains. Of his work he says*: ‘“My own investigations have been mainly in the Cambrian and pre-Cambrian strata, and have involved new and somewhat startling discoveries that helped to show how very much earlier life was developed on our planet than we had previously supposed. These researches have taken into consideration the records left on all the continents and many of the great islands. Field- work, with compass, hammer, and chisel, has been the rule, followed by laboratory and critical comparison of many thousands of specimens of fossil genera and species of ancient marine life, and often study of microscopic sections of rocks and fossils in the hope of finding evidence of the presence of minute and active bacterial and simple algal workers, such as exist in modern seas and lakes, which by their united efforts form great masses of the recent sea and lake deposits.”’ He has worked up and correlated the Cambrian formations and included faunas on the North American continent, has personally discovered large and unique additions to the previously known Cambrian faunas, and has published his researches on the Cambrian faunas of the world; studied and developed the history and sedimentation of 30,000 feet of Algonkian sediments in western North America, and discovered and published an account of the organic remains in the Algonkian. An important find by Dr. Walcott a few years ago of a rich fossil locality in the Burgess shale, near Field, British Columbia, Canada, has given the finest and largest series of Middle Cambrian fossils yet discovered, and the finest invertebrate fossils yet found in any formation, including—besides brachiopods and trilobites — merostomes, holothurians, meduse, annelids, brachiopods, malacostracans, etc. Many of the forms are not yet deseribed and illustrated. His many published works include especially studies of the Cambrian Brachiopoda and Trilobita. A few titles, suggestive of the scope of this work, are: Paleontology of the Eureka District, The Cambrian Faunas of North America, The Fauna of the Lower Cambrian or Olenellus Zone, Pre-Cambrian Fossiliferous Formations, Correlation Papers, Cambrian Brachiopoda, The Cambrian Faunas of China, Discovery of Algonkian Bacteria, Evidences of Primitive Ixfe, and an 1 Evidences of Primitive Life, loc. cit., pp. 235-6. Eminent Living Geologists— Dr. C. D. Walcott. 5 extended series under Cambrian Geology and Paleontology in Smithsonian Miscellaneous Collections, including ‘‘ Appendages of Trilobites ’’ (now in press). . Dr. Walcott’s activity in other directions besides his own scientific field is well known. He is a director and was one of the founders of the Research Corporation of New York City, which is affiliated with the Smithsonian Institution. He is a member of two military committees: chairman of the Executive Committee of the National Advisory Committee for Aeronautics, appointed by President Wilson in 1915, and chairman of the Military Section of the National Research Council. Since 1917 he has been President of the National Academy of Sciences. Of his varied inquiries Dr. Walcott says,’ ‘‘1 have had generous assistance in obtaining collections and exchanging publications with students all over the world, including geologists, paleontologists, zoologists, and paleobotanists in America and Europe, and in far- away outposts of China, Siberia, India, Australia, and New Zealand.”’ In 1888 he visited Wales for the purpose of making a personal study of the type district of the Cambrian system—the district rendered classic by the original labours of Sedgwick and the subsequent researches of Hicks. It was on this visit to England that he presented his Cambrian researches before the International Geological Congress at London. The London Geological Society in 1895 awarded him the Bigsby Medal, and in 1918 the Wollaston Medal. Dr. Walcott is an active member of many scientific and literary bodies, both at home and abroad. These include the National Academy of Sciences (President), American Association for the Advancement of Science (Fellow; Vice-President, 1893), American Academy of Arts and Sciences (associate fellow), American Society of Naturalists, Geological Society of America, American Philosophical Society, Washington Academy of Sciences (President, 1899-1910), Archeological Institute of America (President, Washington Society, 1915-17), Academy of Natural Sciences of Philadelphia (Hayden Medal), Geological Society of London (Bigsby Medal, Wollaston Medal), Société géologique de France (Gaudry Medal), Christiania Scientific Society, corresponding member of l’ Academie des Sciences of Institut de France, Royal Geographical Society of London, honorary member Imperial Society of Naturalists of Moscow, foreign associate Royal Academy of Sciences of the Institute of Bologna, etc. The occasion of Dr. Walcott’s visit to Cambridge, England, in 1909, was a happy one, the degree of Sc.D. being conferred upon him. Other degrees which he has received include LL.D. from Hamilton (1897), Chicago University (1901), Johns Hopkins (1902), Pennsylvania (1908), Yale (1910), St. Andrews, Scotland (1911), and Pittsburg (1912); Ph.D., Royal Fredericks, Christiania (1911), ‘and Se.D., Harvard (19138). Since the entrance of the United States into the great war, in 1 Evidences of Primitive Life, loc. cit., p. 236. 6 Eminent Living Geologists—Dr. C. D. Walcott. 1917, Dr. Walcott has divided his time between war work and the administrative duties of the Smithsonian, but his leisure for research has been curtailed. In spite of this, however, he has prepared a paper of unusual interest to paleontologists, on ‘‘ Appendages of Trilobites’’ (now in press). This represents the fulfilment of the promise to Professor Louis Agassiz, in 1873, that he would undertake the investigation of the structure of the trilobite. To the War Service his contribution has been especially in Aeronautics. He has given two sons to the Air Service, one of whom, Benjamin Stuart Walcott, fell in combat over the German lines December 12, 1917, and the second son, Sidney, is on active service. His daughter, Helen, served for nearly a year as nurse in a French military hospital, and is now in Italy. The present war activities have made heavy claims upon Dr. Walcott’s time and strength, but in spite of this he has again this summer (1918) succeeded in going on an expedition to the Canadian Rockies to continue investigations in Alberta and British Columbia. Dr. Walcott has been favoured by fortune in many ways. A short acquaintance with him suffices to reveal some of the causes which have contributed to his success. His commanding figure is an indication of exceptional energy and physical strength, and on seeing him one is not surprised that at a ripe age he is able to carry out his field-work under arduous conditions. His unwearied industry also strikes one at once, for no opportunity for work is lost. The powers of specialization and generalization are equally developed with him; while missing no feature in the minute anatomy of some organism, he is able ‘‘to think in continents” and has thus contributed largely to the elucidation of physiographical problems connected with Paleozoic times. He can turn at will from one task to another. ‘The onerous duties of administrative work in no wise check the enthusiasm with which he enters into his field labours. Fascinating as is the revelation of the rich faunas of the Cambrian rocks of British Columbia, he also recognizes the importance of the search for organic remains in the barren Algonkian strata, and discovers Beltina and ‘‘a pre-Cambrian (Algonkian) Algal flora from the Cordilleran area of Western America’’. He has been fortunate in his home life. His first wife helped him with ever-ready sympathy throughout the years when he was rising to fame, and the present Mrs. Walcott is already known to the geological world by-her writings. His sons and daughter have laboured with him in the field, and especially in that wonderful and prolific district of British Columbia, where so much of his recent work has been done. Dr. Walcott has been also happy in his environment, especially of later years, when he discovered the remarkable Cambrian faunas in a region which he himself terms ‘‘a geologist’s paradise’’. Amongst the fairest scenes of nature he has toiled month by month and year by year, and unearthed that marvellous series of faunas, one of which is preserved in a rock recalling the Solenhofen Slate alone among geological formations, so faithfully are the most delicate parts of organisms preserved in it. Truly, the Burgess shale is a silent Eminent Living Geologists—Dr. C. D. Walcott. 7 witness of the imperfection of the geological record, which the discovery of its treasures has lessened at a bound. We look forward eagerly to the publication of the full accounts of these Cambrian faunas, of which preliminary descriptions only have yet appeared. But Dr. Walcott has already admitted others to his paradise by the publication of the beautiful photographs and photographic panoramas of the British Columbian Alps, which bear testimony to his skill in yet another direction—as an expert photographer of mountain scenery. Well might the ex-President of the Geological Society (Dr. Harker) state when handing the Wollaston Medal to the Attaché to the Embassy of the United States in London for trans- mission to Dr. Walcott, that “his personal researches have excited interest and admiration wherever geology is cultivated’. Dr. Walcott has many friends in this country who are proud of the friendship. He has been the recipient of honours here; he has encouraged British workers with much kindly help; some of his most brilliant discoveries have been made in the territories of the British Empire; and as we have seen, he has done his work and suffered loss in connexion with the great war for the sake of civilization. He has forged a prominent link in the chain that unites the English-speaking peoples on the two sides of the Atlantic. BIBLIOGRAPHY OF CHIEF SCIENTIFIC PUBLICATIONS. 1875. ‘‘ Description of the Interior Surface of the Dorsal Shell of Ceraurus pleurexanthemus, Green’’: Ann. Lyc. Nat. Hist. New York, xi, pp. 159-62, pl. xi, November, 1875. (Read June 7, 1875.) 1876. ‘‘ Preliminary Notice of the Discovery of the Remains of the Natatory and Branchial Appendages of Trilobites.’? (Advanced print, December, 1876.) 28th Ann. Rep. New York State Mus. Nat. Hist., pp. 89-92, 1879. 1877. ‘* Notes on some Sections of Trilobites from the Trenton Limestone.”’ (Advanced print, September 20, 1877, pp. 3-6.) 31st Ann. Rep. New York State Mus. Nat. Hist., pp. 61-3, Albany, 1879. ae in pamphlet with the following, bearing date September 20, 1877. ““ Note on the Eggs of the Trilobite.’’ (Advanced print, September 20, 1877, pp. 11-12.) Ibid., pp. 66-7, 1879. 1879. ‘‘ Fossils of the Utica Slate and Metamorphoses of Triarthrus becki.” (Advanced print, June, 1879, pp. 18-38, pls. i, ii.) Trans. Albany Inst., vol. x, pp. 18-88, pls. i, ii, Albany, 1879. (Read March 18, 1879.) 1880. ‘‘The Permian and other Paleozoic Groups of the Kanab Valley, Arizona’’: Amer. Journ. Sci., ser. 111, xx, pp. 221-5, September, 1880. 1881. ‘‘ The Trilobite: New and Old Evidence relating to its Organization’? : Bull. Mus. Comp. Zool. Harvard College, viii, No. 10, pp. 191-224, pls. i-vi, March, 1881. 1882. ‘‘ Description of a New Genus of the Order Kurypterida from the Utica Slate’’?: Amer. Journ. Sci., ser. Ill, xxiii, pp. 213-16, March, 1882. 1883. ‘‘Pre-Carboniferous Strata in the Grand Canyon of the Colorado, Arizona ’’: ibid., xxvi, pp. 437-42, 484, December, 1883. ‘‘The Cambrian System in the United States and Canada’’: Bull. Phil. Soc. Washington, vol. vi, pp. 98-102, 1884. (Read November 24, 1883; abstract printed. Separates in December, 1883: J. B. Marcou.) 1886. 1887. 1889. 1890. 1891. 1892. 1894. Eminent Living Geologists—Dr, C. D. Walcott. Paleontology of the Hureka District: Mon. U.S. Geol. Surv., viii, pp. i-xili, 1-298, pls. i-xxiv, figs. 1-6. Date on title-page 1884, but received at Survey March 16, 1885.. ““On the Cambrian Faunas of North America: Preliminary Studies ”’ : Bull. U.S. Geol. Sury., No. 10, pp. 1-74, pls. i-x. i ‘‘ Classification of the Cambrian System of North America ’’: Amer. Journ. Sci., ser. WI, xxxii, pp. 138-57, figs, 1-9, August, 1886. (Read before National Academy of Sciences, April 23, 1886.) ** Second Contribution to the Studies of the Cambrian Faunas of North America’’: Bull. U.S. Geol. Surv., No. 30, pp. 1-222, pls. i-xxxiii, figs. 1-10. ‘““ Fauna of the ‘ Upper Taconic’ of Emmons, in Washington County, New York’’: Amer.. Journ. Sci., ser. I, xxxiv, pp. 187-99, pl. i, September, 1887. ““The Taconic System of Emmons and the use of the name Taconic in Geologic Nomenclature’’: ibid., xxxv, pp. 229-42, March, 1888 ; pp- 807-27, April, 1888; pp. 394-401, May, 1888; with 13 figures and a map. ““On the Relations and Nomenclature of Formations between the Archean and Cambrian, and the use of the term Taconic’: Congr. géol. internat., Compte rendu, 4me sess., Appendix A, Reports of Amer. Comm., 1891 (1888), pp. 69. “ Stratigraphic Position of the Olenellus Fauna in North America and Europe’’: Amer. Journ. Sci., ser. Ill, xxxvii, pp. 374-92, May, 1889 ; xxxviii, pp. 29-42, July, 1889. ““A Simple Method of Measuring the Thickness of Inclined Strata.’’ (Advanced print, June 11, 1889.) Proc. U.S. Nat. Mus. for 1888, xi, pp. 447-8. i ‘“ A Fossil Lingula preserving the Cast of the Peduncle.’’ (Advanced Pa eae 3, 1889.) Ibid., p. 480. (Read December 3, 1887. “Study of a Line of Displacement in the Grand Canyon of the Colorado in Northern Arizona’’: Bull. Geol. Soc. America, i, pp. 49-64, February, 1890. (Read August 29, 1889.) ““The Fauna of the Lower Cambrian or Olenellus Zone’’: Tenth Annual Report U.S. Geol. Surv. for 1888-9, pt. i, pp. 509-774, pls. lxili—xeviii. “Correlation Papers, Cambrian’’: Bull. U.S. Geol. Sury., No. 81, pp. 447, pls. i-iil. “‘The North American Continent during Cambrian Time’’: 12th Ann. Rep. U.S. Geol. Surv. for 1890-1, pt. i, pp. 523-68, pls. xlii—v. “Notes on the Cambrian Rocks of Pennsylvania and Maryland, from the Susquehanna to the Potomac’’: Amer. Journ. Sci., ser. IM, xliv, pp. 469-82, December, 1892. (Read before Philosophical Society of Washington October 29, 1892.) “Notes on the Cambrian Rocks of Pennsylvania, from the Susquehanna to the Delaware ’’: ibid., xlvii, pp. 37-41, January, 1894. “Paleozoic Intra-Formational Conglomerates’’: Bull. Geol. Soc. America, v, pp. 191-8, pls. v-vii, February 5, 1894. ““Note on some Appendages of the Trilobites’’: Proc. Biol. Soc. Washington, ix, pp. 89-97, pl. i, March 30, 1894. “* Pre-Cambrian Igneous Rocks of the Unkar Terrane, Grand Canyon of the Colorado, Arizona,’’ by Charles D. Walcott; with Notes on the Petrographic Character of the Lavas, by Joseph P. Iddings: 14th Ann. Rep. U.S. Geol. Surv. for 1892-3, pt. ii, pp. 497-519 (Walcott) and 520-4 (Iddings), pls. lx-v. ““Geologic Time as indicated by the Sedimentary Rocks of North America’’: Proc. Amer. Assoc. Adv. Sci., 42nd Meeting, Salem, pp. 129-69; Smithsonian Inst., 48th Ann. Rep., 1893 (1894), pp. 301-34, pl. xvi. 1895. 1909. 1910. 1911. 1912: 1913. Eminent Living Geologists—Dr. C. D. Walcott. 9 ‘““The United States Geological Survey’’: Pop. Sci. Monthly, xlvi, No. 4, pp. 479-98, February, 1895. ‘* Aleonkian Rocks of the Grand Canyon of the Colorado’’: Journ, Geol., ili, No. 3, pp. 312-30, pl. vi, April-May, 1895. ‘* Pye-Cambrian Fossiliferous Formations’’: Bull. Geol. Soc. Amer., x oe a pls. xxii-vili, April, 1899. (Read December 30, 1898. ‘“Random, a Pre-Cambrian Upper Algonkian Terrane’’: ibid., xi, p- 3-5, January, 1900. ‘The Cambrian Fauna of India’’?: Proc. Washington Akad. Sci., vil, pp. 251-6, July 24, 1905. ‘* Aleonkian Formations of North-Western Montana’’: Bull. Geol. Soc. Amer., xcii, pp. 1-28, pls. i-xi, May, 1906. ‘Nomenclature of some Cambrian Cordilleran Formations.’? Cambrian Geology and Paleontology, i. Smithsonian Misc. Coll., vol. lii, No. 1, Publ. 1804, pp. 1-12, April 18, 1908. ‘“Mount Stephen Rocks and Fossils’? : Canadian Alpine Journ., Alpine Club of Canada, vol. i, No. 2, pp. 232-48, pls. i-iv, 3 text- pls., Calgary, Alberta, September, 1908. ‘“Cambrian Sections of the Cordilleran Area.’’ Cambrian Geology and Paleontology, i. Smithsonian Mise. Coll., vol. lili, No. 5, Publ. 1812, pp. 167-230 (incl. Index), pls. xiii-xxii, December 10, 1908. é ‘‘Bvolution of Early Paleozoic Faunas in relation to their Environ- ment’’: Journ. Geol., vol. xvii, No. 3, pp. 194-202, March— April, 1909. (Read before Section EH, Amer. Assoc. Adv. Sci., Baltimore Meeting, December, 1908.) ‘“ Olenellus and other Genera of the Mesonacide,’’ Cambrian Geology and Paleontology, i. Smithsonian Mise. Coll., vol. lili, No. 6, Publ. 1934, pp. 231-422 + Index, pls. xxiii-xliv, August 12, 1910. ‘‘Pre-Cambrian Rocks of the Bow River Valley, Alberta, Canada.’’ Ibid., No. 7, Publ. 1939, pp. 423-97 (incl. Index for entire vol.), pls. xlv—xlvi, August, 1910. ‘« Abrupt Appearance of the Cambrian Fauna on the North American Continent.’’ Jbid., vol. lvii, No. 1, Publ. 1940, pp. 1-16, 1 map, 1 text-fig., August 18, 1910. ‘“Middle Cambrian Merostomata.’’ Ibid., No. 2, Publ. 2009, pp. 17-40, pls. ii-vii, April 8, 1911. ‘‘Middle Cambrian Holothurians and Meduse.’’? Ibid., No. 3, Publ. 2011, pp. 41-68, pls. viii—xiii, text-figs. 2-6, June 13, 1911. ‘‘ Middle Cambrian Annelids.’’ Ibid., No. 5, Publ. 2014, pp. 109-44, pls. xvili-xxiii, September 4, 1911. ‘“Middle Cambrian Branchiopoda, Malacostraca, Trilobita, and Mero- stomata.’’ Ibid., No. 6, Publ. 2051, pp. 145-228, pls. xxiv-xxxiv, 2 text-fies., March 13, 1912. ‘‘ Gambro-Ordovician Boundary in British Columbia, with Description of Fossils.’”’ Ibid., No. 7, Publ. 2075, pp. 229-37, pl. xxxv, March 8, 1912. ‘“The Sardinian Cambrian Genus Olenopsis in America.’’ Ibid., No. 8, Publ. 2076, pp. 239-49, pl. xxxvi, March 8, 1912. ‘“ Notes on Fossils from Limestone of Steeprock Lake, Ontario’’: App. to Memoir No. 28, Geol. Surv. Canada, (Reprint) pp. 1-6, pls. i, ii. - “ New-York Potsdam-Hoyt Fauna.’? Cambrian Geology and Paleonto- logy. Smithsonian Mise. Coll., vol. lvii, No. 9, Publ. 2136, pp. 251-304, pls. xxxvii-xlix, September 14, 1912. Cambrian Brachiopoda. Mon. U.S. Geol. Surv., vol. li, pt. i (text), pp- 1-872 (incl. Index), pt. ii (plates), pls. i-civ+deser. pp. 1-363 (incl. Index), text-figs. 1-76, December, 1912. ‘“The Monarch of the Canadian Rockies: The Robson Peak District, British Columbia and Alberta, Canada’’?: Nat. Geog. Mag., May, 1913, pp. 626-39, 12 illus. (incl. long panoramic view). 10 Dr. G, T. Prior—Progress of Mineralogy. ‘“New Lower Cambrian Subfauna.’’ Cambrian Geology and Paleonto- logy, ii. Smithsonian Misc. Coll., vol. lvii, No. 11, Publ. 2185, pp. 309-26, pls. l-iv, July 21, 1913. “* Cambrian Formations of the Robson Peak District, British Columbia and Alberta, Canada.’’ Ibid., No. 12, Publ. 2186, pp. 327-43, pls. lv-lix, July 24, 1913. , ‘The Cambrian Faunas of China’’: Research in China, Carnegie Institution of Washington, vol. iii, Publ. No. 54, pp. 1-375 (inel. Index), pls. 1-29, text-figs. 1-9. 1914. °* Dikelocephalus and other Genera of the Dikelocephaline.’? Cambrian Geology and Paleontology. Smithsonian Misc. Coll., vol. lvii, No. 13, Publ. 2187, pp. 345-498 (with Index to entire vol.), pls. lx-Ixx, text-figs. 13-20, April 4, 1914. ‘“Pre-Cambrian Algonkian Algal Flora.’’ Ibid., vol. lxiv, No. 2, Publ. 2271, pp. 77-156, pls. iv-xxiii, July 22, 1914. 1915. ‘* The Cambrian and its Problems in the Cordilleran Region: Problems of American Geology’’ : Dana Commemorative Lectures (delivered Silliman Foundation, December, 1913, Yale University), Yale Univ. Press, ch. iv, pp. 162-233, pls. i, ii, text-figs. 1-8. “Discovery of Algonkian Bacteria ’’ (presented to National Academy of Sciences, April 9, 1915): Proc. Nat. Acad. Sci., vol. i, pp. 256-7, text-figs. 1-3. 1916. “‘Cambrian Trilobites.’’ Cambrian Geology and Paleontology, iii. Smithsonian Mise. Coll., vol. lxiv, No. 3, Publ. 2870, pp. 157-256, pls. xxiv—xxxvili, January 14, 1916. ‘‘ Relations between the Cambrian and Pre-Cambrian Formations in the Vicinity of Helena, Montana.’’ Ibid., No. 4, Publ. 2416, pp. 259-301, pls. xxxix—xliy, text-figs. 10-13, June 24, 1916. ‘*Cambrian Trilobites.’’ Ibid., No. 5, Publ. 2420, pp. 303-570 (incl. Index), pls. xlv-Ixvii, September 29, 1916. “Evidences of Primitive Life’?: Smithsonian Report for 1915, pp. 235-55, pls. i-xviii, Publ. 2389. 1917. “‘ The Albertella Fauna in British Columbia and Montana.’’ Cambrian Geology and Paleontology, iv. Smithsonian Misc. Coll., vol. lxvii, No. 2, Publ. 2445, pp. 9-59, pls. i-vii, May 9, 1917. Fauna of the Mount Whyte Formation.’’ Ibid., No. 3, Publ. 2480, pp. 61-114, pls. viii-xiii, September 26, 1917. 1918. ‘‘ Appendages of Trilobites.’? Ibid., No. 4, Publ. 2523, pp. ; pls. xiv—xlii, 3 text-figs. (in the press). ee II.—Revrew or Proeress or Mineratocy From 1864 ro 1918. By G. T. Prior, M.A., D.Sc., F.R.S., Keeper of the Mineral Department of the British Museum (Natural History). BRITISH MUSEUM official may perhaps be pardoned if, in a review of the progress of mineralogy since the first appearance of the Grotogican Macazine, he begins with a reference to scientific work done in the Museum with which the Editor was so long associated. At the time when the Magazine first saw the light the Keeper of the Mineral Department was the late Professor Nevil Story-Maskelyne. He was one of the first to grasp that efficient tool for deciphering mineral aggregates which had been provided by Nicol and Sorby in the thin-section. He was engaged in the particular work to which Keepers of that Department have since appeared to consider they must in duty bound devote much of their time and energy, viz. the investigation of meteorites, and, assisted by the microscopic examination of thin slices of these bodies, he was Dr, G. I. Prior—Progress of Mineralogy. il soon able to announce the discovery in them of several new species, one of which, the sulphide of calcium, oldhamite, must have been formed under conditions very different from those which prevail on the earth’s surface. Shortly before this time the sciefces of both geology and mineralogy, having passed through times of stress, had been placed upon the sure foundations on which the present superstructures have been built. In the case of geology, starting with the broad conception of the earth’s crust as made up of rocks, the founders of the science, after a prolonged and bitter struggle between ‘‘neptunists’’ and “‘ylutonists’’, had at length learned, by accepting truth from both sides, to distinguish clearly between two main types of rocks, the sedimentary, owing their origin to superficial agencies acting on the earth’s surface, and the igneous, resulting from deep-seated agencies acting from the earth’s interior. Guided by the principle that the present is the key to the past, which had been enunciated by Hutton and enforced by the teaching of Lyell, the geologist soon saw spread before him the ordered sequence of the sedimentary rocks, with their fossils giving a record, imperfect though it might be, of the gradual evolution of plant and animal life down the ages. Along these lines geology, on its stratigraphical and palxontological side, could develop, and has indeed continued to develop up to the present day, without feeling the necessity for paying a great amount of attention to the mineral composition of the rocks with which it dealt. ‘he investigation of the igneous rocks, however, presented a different problem. After the main facts of the processes of vulcanism and igneous intrusion had been grasped, further progress might have been barred for a long time but for such work as that of Sorby in directing attention to the use of the microscope in determining the mineral composition of rocks. The branch of microscopical petrography thus initiated, and developed later by the exertions of Zirkel, Rosenbusch, and Teall, forms the connecting link between geology and mineralogy. As has been rightly said, mineralogy is the chief buttress on which the science of rocks, or petrology, rests; for to attempt to study rocks without minerals would be like trying to investigate and classify a group of animals by their external features with little reference to their internal anatomy. Into an error of this kind mineralogy, indeed, had been in danger of falling in the earlier stages of its career. Under the influence of Mohs an attempt had been made to restrict the study of minerals to their natural history characters, such as crystalline form, hardness, and specific gravity, to the exclusion of the chemical properties. Mineralogy without elements would thus have been in a state comparable to that of geology without minerals. No branch of science, however, as pointed out by Sir Henry Miers in a recent lecture on this same subject before the Chemical Society, can afford to maintain a position of splendid isolation for long. Sooner or later in its development there comes a stage when for any further advance it becomes necessary to seek the aid of other sciences in order to elucidate the 12y Dr. G. T. Prior—Progress of Mineralogy. new problems presented. Theimportance of theaccurate determination of the chemical composition of minerals, as insisted upon by Berzelius and Rammelsberg, was too obvious to be long neglected; and in 1850 J. D. Dana, in the third edition of his System of Mineralogy, the textbook which has since become the standard work of reference for English-speaking mineralogists, rejected the natural history, classification, ‘‘ with its classes, orders, genera, and Latin names,’’ as set forth in the first edition, and replaced it by a chemical one. As Dana remarked, however, the natural history classification had some advantages in ‘‘ displaying many of the natural groups which chemistry was slow to recognize”, for example, the felspars. A reconciliation of the purely chemical and the natural history classification was effected by Gustav Rose, who in 1852 published his ecrystallo-chemical system under which crystalline form was given almost as much importance as chemical composition in the distribution of minerals into groups. This was the system which was adopted by Story-Maskelyne for the re-arrangement of the mineral collection of the British Museum. ‘The general acceptance of such a system, in which minerals were classified, in the first place by chemical composition, and in the second place by crystallographic characters so as to bring together members of isomorphous groups, marked a distinct advance in the science of mineralogy. It was in the very year in which the Grorocican Magazine first appeared that Tschermak published his discovery of the nature of the felspar group. The fact that minerals with such apparently dissimilar chemical compositions as albite and anorthite should erystallize together in all proportions threw a new light upon the principle of isomorphism, and helped to pave the way towards the modern view that it is the arrangement in space of the atoms themselves that determines the crystal structure. During the period under review, indeed, the great problem which has exercised the minds of mineralogists has been the determination of the connexion between the chemical composition, the crystalline form, and the physical (more especially optical) characters of minerals. The close interrelation between optical and crystallographic characters had been to a large extent already recognized by the work of Brewster, who had shown how different types of crystals differed in their behaviour towards polarized light. The gradual accumulation of knowledge which led to the distribution of crystals into groups or systems, each distinguished from the others by the optical characters of its members, is well brought out in the Introduction to the Study of Minerals, one of the British Museum Guidebooks, first published in 1884, for which geologists desirous of gaining some knowledge of minerals owed a debt of gratitude to Sir Lazarus Fletcher, the successor to Story-Maskelyne in the Keeper- ship of the Mineral Department. The exact determination of the optical characters of rock-forming minerals such as the felspars, pyroxenes, and amphiboles, which has been rendered possible, first by the researches of Des Cloizeaux and Tschermak, and later by the improvements in apparatus and methods effected by more modern =e wy 48 | LL 2S © 4 _ \ Dr. G. T. Prior—Progress of Mineralogy. 13 workers, of whom mention may be made of Becke, Fedorov, and Wright, is of the utmost importance for the development of petrology. Such advances have been made in this direction that it will soon be possible from the determination of the optical characters oi any one of these minerals, as seen in thin-sections under the microscope, to make fairly accurate deductions as to its other properties, including the chemical composition. Steps towards the solution of the other branch of the problem with which mineralogists have been concerned, viz. the connexion between crystalline structure and chemical composition, had also been taken, before the period under review, in the study of isomorphous ups. More recently, series of brilliant researches, oi which those made by Tutton on isomorphous groups of sulphates and selenates are the most remarkable, have shown that the individual members of such groups are not crystallographically absolutely similar, but that quite definite and concordant, though minute, changes in the crystal form and optieal characters are produced by the replacement oi one metal by another. Most notable also in this connexion are Penfield’s classic demonstration of the isomorphous replacement of fluorine and hydroxyl, and his investigation of the morphotropie relations oi the members of the humite group of minerals. It was as far back as 1850, however, that perhaps the most striking advance was made towards the goal to which mineralogists were striving. In that year was published what might appear at first sight to have little bearing upon the matter, viz. the mathe- matical memoir of Bravais on the regular arrangement of points in space. Bravais’ work was a more complete development of the geometrical investigations of Frankenheim on parallelepiped networks of points known as space-lattices. In a space-lattice points are arranged in space for the most part at the intersections of three sets of planes, the planes in each set being parallel and spaced at equal distances apart. In such an arrangement space is divided up by the points into parallelepiped cells, just as the space of a room may be regarded as divided up into so many cubie inches, the shape of the cell depending upon the inclinations to each other of the three sets of planes, and upon the distances apart of the parallel planes in the three sets. It was assumed that as crystals are homogeneous structures they must be built up of units occupying the position of points in space-lattices; and according to the particular kind of space-lattice, ie. to the shape of its elementary parallelepiped cell, erystals could be divided into the same seven systems into which they had been grouped by the consideration of crystal-symmetry. Since the publication of Bravais’ memoir erystallographers have realized that crystals can be divided according to the degree of symmetry they exhibit, ie. according to the number of planes and axes of symmetry they possess, into thirty-two distinct classes, and that these may be regarded as to some extent mutually independent, _ althongh capable of being distributed through the seven larger systems according as they have certain geometrical and physical relations in common. The fact that only thirty-two types of symmetry are possible in crystals had been discovered by Hessel as 14 Dr. G. T. Prior—Progress of Mineralogy. far back as 1830, and rediscovered by Gadolin in 1867, but the actual grouping of crystals into these classes is of comparatively recent date; for although prominence is given to it in Miers’ Mineralogy, published in 1902, and in Lewis, Crystallography, published in 1899, it is not taken into account in Story-Maskelyne’s Morphology of Crystals, published in 1895. Now space-lattices only sufficed to represent the symmetry of the most symmetrical (holohedral) class in each system. It has been the work first of Sohnke and later of Schonflies, Fedorov, and Barlow to show how all the thirty-two types of symmetry recognized in erystals can be represented by point-systems, which are generally reducible to a certain number of interpenetrating space-lattices in each case of the same kind. The kind of space-lattice determines the system, but the mode of interpenetration of several lattices of the same kind determines the particular class in that system. In setting up a erystal, crystallographers have now in most eases to choose as axial planes three faces which they have reason to suppose are parallel to three sides meeting in a corner of the elementary cell of the space-lattice. Recently Fedorov, by choosing crystallographic axes somewhat on these lines, has prepared a general table of the characteristic angles of all measured crystals, which makes it possible to identify quickly from its crystals any substance that has been previously measured. The question now arose as to the nature of the units involved in the crystal structure. The old notion that the crystal-molecule consisted of a polymerization of many chemical molecules was soon discarded, and, through such a work as that of Tutton, the idea was gaining ground that the units in the erystal structure might be single molecules or even the atoms themselves, when Barlow and Pope brought forward their well-known valency theory, according to which the crystal structure of any chemical compound can be explained by the ‘‘ close-packing”’ of spheres representing the atoms of its molecules, the sizes of the spheres being approximately pro- portional to the valencies. This theory has been applied with a fair measure of success to many organic compounds as well as minerals, though the recent: demonstration, by means of X-ray experiments, of the equality in volume of the elementary cells of the space- lattices of crystals of ammonium sulphate and rubidium sulphate, would appear to suggest that some modification of it may be necessary which shall take into account other properties of the atom besides the valency. Quite recently, as all the world knows, actual experimental proof has been forthcoming of the space-lattice arrangement in crystals. To Laue first came the truly brilliant inspiration that, just as a closely ruled (1,000 lines to the inch) diffraction grating behaves towards light with its wave-lengths measured in thousandths of a millimetre, so it was conceivable would the parallel planes of atoms, as arranged in interpenetrating space-lattices in a crystal, behave as diffraction gratings to X-rays with their wave-lengths (of the order 10-% cm.) so infinitely more minute than those of light. The experimental testing of this stupendous idea was marvellously Dr, G. T. Prior—Progress of Mineralogy. 15 successful. Photographic plates exposed to X-rays which had traversed plates of crystals showed spots of maximum effect which were distributed in accordance with the symmetry of the crystal. In the hands of W. H. Bragg and W. L. Bragg a modification of this method of experiment has given results, the most reasonable interpretation of which fixes the actual arrangement in space of the atoms in crystals of many minerals. In crystals of common salt, for example, the experimental data indicate that the atoms of sodium and chlorine are each distributed on a separate space-lattice of which the elementary cell is a centre-faced cube (i.e. a cube with points not only at the corners but also at the centres of faces), the two lattices interpenetrating in such a way that the sodium and chlorine atoms oceur alternately at equal distances apart. In another cubic mineral, iron pyrites, the three atoms of its molecule are again distributed on centre-faced eube lattices, but the interpenetration of the three lattices is so much more complex as to account for the fact that whereas salt crystallizes in the most symmetrical holohedral class, iron pyrites belongs to the less symmetrical pyritohedral class. With the account of this brilliant consummation this review may well come to a close. Limits of space allow of a reference only to the wonderful series of experiments by van’t Hoff and his pupils on the Stassfurt salt deposits, which have shown how their minerals separated from solution; and to the investigations by Vogt, Doelter, and the band of energetic workers in the Geophysical Laboratory at Washington on the problem of the crystallization of silicates and sulphides from fused magmas. These researches which are still in progress are of great geological interest, as they may be expected to throw much light upon the origin of rocks and ore deposits. Other recent investigations, also having their appeal to geologists, are the determinations by Fenner of the temperatures of inversion of quartz, tridymite, and cristobalite, which enable these silica-minerals to be used as geological thermometers; and the use made by Joly, Strutt, and others of radioactive work on the rate of disintegration of unstable elements such as uranium and thorium in order to measure geological time, and thus to help towards the solution of the vexed question of the age of the earth. Many of these researches, however, as well as the attempts, both experimental and theoretical, made by Clarke, Tschermak, and others, to elucidate the chemical constitution of silicates, have been the subject of some controversy ; and none have as yet reached such a climax as the demonstration of the atomic structure of crystals. This last attainment, it may be noted, has been the result of a gradual extension of investigation from great things to the infinitely small. The science of geology began with the study of rocks, the large bodies which constitute the earth’s crust. In order to determine the composition of rocks geology had to seek the aid of mineralogy. The latter science, in its turn, after concerning itself at first mainly with the natural history characters of minerals, had to apply for knowledge of their elemental composition to the science of chemistry which it had itself originally created. Finally physics and mathematics had to be invoked in order to explain how the 16 A Mines Department for the United Kingdom. atoms of the elements are arranged in space in order to produce those exquisite shapes, the crystals, in which minerals generally occur. It may be'that the problem of crystal structure will eventually receive its complete solution by a continuation of the same process in making use of the knowledge now being acquired of the complexity of the atom and the immense forces stored up in it. Mineralogists, having done so much for erystals, may then perhaps direct more attention to the study of non-crystalline colloidal minerals, and thus possibly forge a connecting link with the biological sciences. In conclusion, the dominant impression produced by a review of the progress of mineralogy during the past half-century is that it 1s only in their initial stages that natural history sciences can attempt to keep in rigid compartments mutually independent of each other. As they continue to advance the greater becomes the necessity, and this is true not only of those which concern themselves with the inorganic world but also of those which deal with the living things upon it, to stretch out for aid to the sciences which really stand at the base of all others—chemistry, physics, and mathematics. In the future it is probable that a much more thorough training in these fundamental sciences than is at present considered sufficient will be regarded as an essential preliminary to the proper study of any department of natural history. LTII.—A Mines Department For tHe Unirep Krnepom. fW\HE formation of a new Government organization to foster and promote the interests of the Mining Industry of the United Kingdom has been recently proposed in two distinct quarters. The Coal Conservation Committee of the Ministry of Reconstruction, which issued its report (Cd. 9084) early in the past year, recommended the establishment of a Ministry of Mines and Minerals, to be presided over by a Minister with a seat in Parliament; while in a report to the Minister of Munitions, issued as a white paper (Cd. 1984) on November 15, Sir Lionel, Phillips, late Controller of the Department for the development of Mineral Resources in the United Kingdom, favours the setting up of a Mines Department, to be attached to one of the existing great Departments of State. In a country like ours, which has probably greater mineral wealth than any area of equal size on the globe, and where the development of vast untapped resources of coal and iron-ore is to some extent hampered by ancient vested interests, the necessity for an organiza- tion of the kind indicated scarcely needs any advocacy. We can therefore confine ourselves to the discussion of the functions that such a Mining Department should be designed to fill. Some of them are already performed by various existing Government departments. Thus the Home Office administers the legislation affecting mines and quarries and, in connexion therewith, carries out an inspection by qualified officers: it also collects and publishes in an annual report certain statistics regarding accidents, labour, and output; and it conducts examinations for colliery managers’ certificates. The Board of Trade collects, under the Census A Mines Department for the United Kingdom. 17 of Production Act, 1906, particulars of the quantity and value of the output of coal, metalliferous minerals, and of works engaged in the smelting of metals; and duringthe War it has been largely concerned with the regulation of the supply and distribution of coal and coke. The Board of Education, in its capacity as administrative head of the Geological Survey (in succession to the old Science and Art Department), has to do with the Geological Survey of the United Kingdom, i.e. with the preparation of geological maps, explanatory memoirs, and of special Reports on Mineral Resources, as well as the maintenance of a Museum of geological collections and economic resources. The Moods, Forests, and Land Revenues, through its Commissioner, acts as Gaveller of the Forest of Dean and also exercises the rights of the Crown in respect of mines under the sea, below high-water mark, in all parts ofthe Kingdom. Similar Crown rights are exercised by the Duchies of Lancashire and Cornwall. During the War the Ihnistry of Munitions has, under the Defence of the Realms Act, exercised many of the functions of a Mines Department. Its activities with regard to minerals have separated naturally on the lines of ferrous and non-ferrous. Through its Iron and Steel Department under the administration of Sir John Hunter and Colonel Charles Wright, C.B., it has been able to develop rapidly home supplies of iron-ore so as to more than make up for any loss of foreign supplies due to the activities of the enemy submarines; in connexion with this, it became necessary, in order to properly gauge the industrial situation, to organize the collection of very complete statistics of production of raw and semi-finished materials, and it is understood that in the course of this work a most valuable series of records has been accumulated. The Department for the Development of Mineral Resources was established for the purpose of increasing in the United Kingdom the supply for War purposes of minerals other than coal and iron. Sir Lionel Philli ips was made Controller; and his Report, which has just been issued, is the one referred to above. The proposal made by the Coal Conservation Committee is that the duties hitherto performed by so many different Government bodies should, with certain specified exceptions, be transferred to and administered by a Ministry of Mines for the United Kingdom. The functions of such a Ministry would from the foresoing appear to be: to collect statistics of production, consumption, and metal requirements of the United Kingdom; to provide for the certification of the managers of all mines and quarries; to safeguard the health and safety of the employees by administering the legislation affecting mines and quarries; and finally, to set up machinery to deal with such local mining problems as the working of barriers, the drainage of waterlogged areas, wayleaves, royalties, etc. In Sir Lionel Phillips’ scheme it is suggested that there should be attached to the proposed 1] Mines Department, (1) an Imperial Mineral Resources Bureau, forming a link with the self-governing Dominions; (2) a Mines and Minerals Commission to watch and foster the interests of the Empire in the output and trade in mineral and metallic products. Other notable points in his scheme are (1) the DECADE VI,—VOL. VI.—NO. I. 2 18 R. D. Oldham—The Interior of the Harth. appointment of commissioners authorized to take action in cases of improper exploitation of properties, or unreasonable or prohibitive conditions imposed by landowners for royalties and wayleayes; (2) the provision and administration of a fund for the purpose of undertaking experimental work. Since Sir Lionel Phillips wrote his report an Imperial Mineral Resources Bureau has been set up. It has been designed as an Imperial link between the respective Mines and Mineral Departments of the self-governing Dominions, India, and the United Kingdom, and its constitution would not appear to permit of its being attached to a Mines Department of the United Kingdom. The Bureau is, we understand, already at work on its internal organization. It is an Imperial body to be incorporated by Royal Charter under the Presidency of the Lord President of the Council, with a governing body containing representatives appointed by the self-governing Dominions, India, and the United Kingdom, as well as certain technical men appointed by the Minister of Reconstruction to represent the mineral, mining, and metal industries generally. In the collection of statistical information it will work through the Mines Departments of all parts of the Empire, including the United Kingdom, and as an Imperially constituted body its relations to a Home Mines Department should be of similar nature to those of the self-governing Dominions. From what has been said, however, it must be clear that it would be a great advantage for the dispatch of important business relating to the mining industry of this country to bring under one official head the functions performed by so many different governing bodies. Whether an independent Ministry should be formed or to what existing Department of State a Mines Department should be attached are questions of comparatively minor importance. But if a Ministry to deal with Commerce and Industry were to be formed this would obviously be the proper home fora Department of Mines and Minerals, just as in France the Conseil général des Mines is a department of the Ministre des travaux publies. 1V.—Tae Inrprior oF tHE EHarru. By R. D. OLDHAM, F.R.S., F.G.S. Being the Introduction to a Geophysical Discussion organized by a Committee of the British Association for the Advancement of Science, and held in the rooms of the Royal Astronomical Society on November 19, 1918. HEN I received the invitation to open this discussion my first feeling was of diffidence, for, the interior of the earth being necessarily inaccessible to direct observation, the solution of the problems connected with it has principally been left to mathematical research, and this must remain the final court of appeal. In these circumstances it seemed verging on presumptuousness to address an audience consisting so largely of mathematicians in inauguration of a discussion on the interior of the earth. Second thoughts showed R. D. Oldham—The Interior of the Earth. 19 that there was much to be said against this view, for, though mathematics is the court of appeal, it can only decide on the facts placed before it by the sciences of observation, and so the discussion seems profitably prefaced by a statement of the leading facts which have been collected, and those conclusions which are so directly derived from them as to have almost the validity of observation. The first, and still one of the most important, of these observations is that the temperature rises regularly to the greatest depth yet penetrated into the earth, the rate of increase being on the average about 1° C. for every 25 m. of depth; we also know that at depths from which volcanic eruptions take place the temperature reaches at least 1000° C. So long as the nebular hypothesis held undisputed sway, it was natural to suppose that the increase of temperature was continuous to the centre of the earth, and, as long ago as 1793,’ we find Benjamin Franklin indicating the necessary corollary from this, that below a certain depth the material, of which the earth is composed, must necessarily be in a molten, and, at a still greater depth, be converted into a gaseous, condition, an hypothesis very similar to that associated in recent times with the name of Arrhenius. The fundamental assumption on which this deduction is based has been sapped by the discovery that the radium content of the outer layers of the earth is amply sufficient to account for the whole of the temperature gradient observed in its superficial portion, and, other considerations being ignored, the hypothesis which has been seriously proposed, that the innermost parts of the earth may be intensely cold, approaching the absolute zero temperature of space, is a possible one. We have also the demonstration that the earth as a whole is something lke twice as rigid as an equal-sized globe of solid granite, which precludes the assumption that the interior can be in a fluid or gaseous condition in any ordinary sense of the word, but here we must allow for the effect of pressure. When it is remembered that at a depth of but 4km., or about 23 miles, the pressure is already greater than the crushing strength of the strongest known rock, and that at the centre it is about three thousand times as great as this, it becomes evident that the properties of matter may be very greatly modified and that the terms used to describe the three states, as we know them under surface conditions, may need to be used in a very esoteric sense when transferred to the interior of the earth. For the present all that need be said is that material, which can be shown to be from twice to six times as rigid as strong granite, can only be described as fluid or gas in a very Pickwickian sense of the word, and it is_possibly a mere accident that the threefold division of the interior, outlined by Benjamin Franklin, comes so near that which I propose to show is the deduction to be drawn from the present state of knowledge. Taking the outer layers of the earth first, we find that the rocks which are exposed at the surface consist in part of material which has been disintegrated by the processes of surface denudation, trans- ported, deposited, and resolidified, and partly of rock which has not 1 Trans. Amer. Phil. Soc., iii, pp. 1-5, 1793. 20 R. D. Oldham—The Intervor of the Earth. yet undergone these processes, but is thoroughly cooled and solid in every sense of the word. To the greatest depth yet reached the rocks are of this type, and it evidently continues for some distance below the depths which can be reached by direct observation or by immediate deduction. This outermost portion of the earth, in which the physical condition is similar to that of the surface rocks, is commonly known in geology as the crust, a name which originated in the days when the earth was supposed to consist of a molten interior and an outer solid crust, and has survived that supposition for want of a better, and after all the word does not necessitate a fluid interior; a loaf of bread, for instance, has a crust, though the interior should be solid. At the present day the term means no more than the outer layers in which composition and constitution have not undergone any great change, as opposed to the more deeply seated material, which differs on one or both of these characteristics. The thickness of this outer crust has been estimated by various methods, the increase of temperature, the pressure under which certain minerals must have been formed, the strength of the crust as indicated by the anomalies of gravity, and some others, all of which agree in putting the lower limit at about 50km., or some 30 miles, well under one-hundredth of the radius of the earth. In the outer regions of the crust geological investigation has shown that movements of displacement have taken place on a large scale. Over widths of some hundreds of kilometres rocks have been compressed to the extent of one-third to one-half or less of their original extension, as is shown by the folds into which originally horizontal strata have been thrown. In other cases clean-cut, gently sloping, or horizontal fractures have been recognized, and, along these fractures, displacements have taken place to the extent, well established, of over 60 km. and in some cases possibly of over double this, or from 3° to 1° of the circumference of the earth. In other places there is evidence of extension, much less capable of measurement than. the compression, which, though probably smaller on the whole than the compression, may be comparable in amount. Displacements in a vertical direction have also been well determined, along defined surfaces of fracture the displacement of opposite sides of faults has been established up to about 5 km., and possibly to half as much again, and, as regards places less than a couple of degrees apart, such as the crests of the Himalayas or Andes compared with the plains at their foot, or the mountains of Japan with the bottom of the Tuscarora deep, the vertical displacements may be as much as 15 km. The cause of these great earth movements is still an unsolved problem of geophysics. At one time they were generally attributed to compression of the earth’s crust through contraction due to gradual cooling, and the notion is by no means extinct, but the curiously local distribution of the compression is against this interpretation, no less than the fact that the amount is largely in excess of any con- traction permissible on this hypothesis, and besides we have the equally well-established facts that regions of very considerable extent show signs of tension and expansion of their dimensions. R. D, Oldham—The Interior of the Earth, 21 Especially in the case of the great thrust-faults is explanation difficult ; the appearances are such as suggest a simple fracture and displacement by compression due to approach to each other of the limits of the region affected, but it can easily be shown that the thrusts involyed in this explanation are many times greater than those which could be transmitted by the material of which the blocks are composed. The final explanation must wait until it can be treated by one who is at the same time fully cognisant of the geological results and of the physical principles involved, probably also till a further advance is made in our knowledge of the physical properties of the material under conditions such as exist, even at the comparatively small depths involved. Leaving this question aside, it is clear that extensive displace- ments have taken place in the outermost layers of the crust, and these are presumably taken up, possibly in a somewhat different form, by the lower layers, but in any case necessitate that, below the rigid and solid crust, must come material which possesses some of the properties attributed to a fluid, though not necessarily more than the power of changing its form when exposed to stresses of sufficient magnitude and of long enough duration. This has been recognized for some time, and we were content to accept the general conclusion without giving it a name, but this does not satisfy American thought, and Professor J. Barrell has not only introduced the name asthenosphere for the region of material comparatively weak as against permanent stress, but has given a numerical estimate of this weakness or strength. According to him the material at the weakest part of the asthenosphere reached by his investigation, placed at 400km. from the surface, is about 45 of that of massive surface rocks, and of the order of a capacity of sustaining stress differences of about 1,000lb. per sq. in, with extreme permissible limits of 100 and 5,000 lb. per sq. in. At this depth the conclusions drawn from his method of deduction become distinctly doubtful, but, at the lesser depth of 50 km., the strength is Only about six times that quoted and at 100km. about four times this amount.} The nature of the transition from the solid crust, or lithosphere, to the underlying asthenosphere is of interest, and on it two lines of reasoning can be brought to bear. First, we have Professor Barrell’s calculations, according to which the permanent strength between the depths of 20 and 30 km. amounts to about four to five times that of granite, and at a depth of 50km. to only one-quarter, showing a very rapid diminution of strength at depths below 80 km. and a tolerably abrupt transition from the crust to the underlying material. The other line of reasoning depends on the phenomenon of reflection of earthquake waves. It is now pretty well established that long distance records, when clear enough, show the arrival not only of waves which have travelled from the origin by a direct path, but of others which have been reflected at or near the surface. .In the mathematical treatment of these waves it is necessary to assume 7 Journal of Geology, xxiii, p. 44, 1915. 22 R. D, Oldham—The Interior of the Harth. a spherical body with a definite outer surface, from which reflection takes place, and it was not unnatural to regard this as the outer surface of the earth, but there are some very real difficulties in the way of this interpretation. Just thirty years ago Dr. C. G. Knott showed! that, in the heterogeneous material of which the outer layers of the earth are composed, simple condensational and dis- tortional waves could not be transmitted, as each would undergo a breaking up into two forms at every passage from rock of one kind to that of another; ten years later Professor M. P. Rudzki further showed * that only a very small proportion of known rocks possessed those characters of elasticity which would enable them to transmit unaltered the two simple forms of elastic waves, and the records of seismographs show that the movement of the wave particle at the surface is of a very complicated nature, having no relation to the simple movements required by the theory of reflection. For these reasons it seems probable that the reflection, of which we find evidence in long distance records, does not take place at, but a short distance below, the surface, and it is natural to place it at the limit where the more heterogeneous rocks of the outer layer pass into the more homogeneous material of the central core—in other words, at the lower limits of the crust or at about 30 km. below the outer surface. Professor Barrell’s figures suggest that the limit is probably sufficiently defined to give rise to reflection, and the fact that the reflected waves are not always equally conspicuous is in consonance with the natural assumption that the lower limit of the crust may be more sharply defined in some places than in others, an assumption which is strengthened by fact that these reflected waves are especially conspicuous where the point of reflection lies under the great nexus of mountains forming the Pamir Plateau and the ‘‘ Roof of the World”. It is not unnatural to suppose that this region, unique as regards surface features, should be equally singular in the character of the under surface of the crust, and so give rise to the more than usual prominence of the reflected waves, where incidence takes place under this region. For the rest of the interior of the earth we are principally dependent on the results obtained by the modern development of seismology. When it was recognized that the long distance records of great earthquakes represented the arrival of mass waves which had travelled through the earth it must have occurred to more than one worker that they would give information regarding the constitution of the material traversed by the wave paths, but I know of no published work previous to a paper by myself, read before the Geological Society in February, 1906, on the ‘‘Constitution of the Interior of the Earth as revealed by Earthquakes’’,’? to which, doubtless, I owe the honour of having been invited to address you to-day, and in treating the subject the most convenient course + ' Trans. Seismol. Soc. Japan, xii, pp. 115 ff., 1888. ® Beitriige z. Geophysik., iii, pp. 519-40, 1898. = Quart. Journ. Geol. Soc., Ixii, p. 456, 1906. R. D, Oldham—The Interior of the Earth. 23 will be to outline the position as there presented, and the modifica- tions which have been introduced by subsequent work. In 1905 there were twelve earthquakes of which direct and accurate knowledge was available of the place and time of origin, and two of which the place was known, but the time had to be inferred from distant records. Tabulating the records of these earthquakes, it was found that the intervals taken by the first and second phases to reach the place of record increased regularly up to a distance of about 120° from the origin. The rate of transit increased more rapidly at first, less rapidly later, and showed that the deeper the wave path penetrated the greater became the rate of transmission, which meant that the wave paths were curved with a convexity towards the centre of the earth. Up to 120° there was no breach in the regularity of the time curve, and the ratio between the rate of propagation of the condensational and distortional waves remained much the same; beyond 120° distance an irregularity appeared, the first phase, or commencement, was appreciably delayed, and the second phase completely disappeared, only at about 140° did something reappear which was recorded as second phase, but must either be distinct from the second phase at lesser distances, or be delayed by about ten minutes in its arrival. From these facts it was concluded that the earth, down to the depth reached by wave paths emerging at 120°, or to a little more than half the radius measured from the surface, was composed of material capable of transmitting the two primary forms of wave motion, and that down to this depth there was no indication of any change of condition, the increase in elasticity, indicated by the increasing rate of propagation, being no more than might be attributed to the increased pressure and compression of the material. Beyond this depth there is a rapid transition to a material which can only transmit the condensational waves at a somewhat reduced rate, and is either incapable of transmitting the distortional waves, or transmits them with a reduction to about half the velocity attained in the lower parts of the outer shell; at that time it was impossible to decide between the two alternatives which were both presented, with some leaning towards the former. In dealing with subsequent developments it will be convenient to take the two parts of the time curve, and of the resulting parts of the earth’s interior separately. Beginning with the outer shell the first work to be noticed is the often quoted paper by Professor Wiechert, which appeared in 1907,! where the subject is treated in a more elaborately mathematical form, and appended to it is a detailed discussion of the records by K. Zoppritz, the most important part of which, from the present point of view, is the discussion of the depth reached by the wave paths. For those emerging up to a distance of about 45° the depth reached by the two wave paths is about the same, and increases rapidly at first, then less rapidly ; from 45° to about 70°, where the depth reached is about 1,400 to 1,500 km., there is very little increase, but a considerable difference 1 ““ Ueber Erdbebenwellen ’’; Gottingen Nachrichten, 1907. 24 R. D. Oldham—TPhe Interior of the Earth. in the depth reached by the two forms of waves; beyond that distance the depth reached increases again, and gradually becomes more equal for the two forms of wave motion till the limit of about 120° is reached. In detail these results have been modified by later work and more exact and numerous determinations of the time intervals, which Professor H. H. Turner has, within the last three years, found to require considerable corrections; it is also a fact that the mathematical methods were not altogether sound, and quite recently the problem has been tackled anew by Dr. C. G. Knott.! He informs me that he has succeeded in solving the integrals in an unequivocal manner, no longer needing the use of any assumptions, as had previously been used by himself and by Professor Wiechert. From this he has computed and plotted the wave paths for various distances, which show that those emerging at from 45° to about 75° are crowded together in their deepest-lying parts, in a zone lying just outside about one-quarter of the radius from the surface, or at a depth of 1,300 to 1,500km. The flattening of the wave paths in this region shows that the increase in rate of propagation suffers a check, and in the case of waves emerging at 73° the lower part of the path is actually concave towards the centre, indicating a Ee vCEay decrease in the rate of travel.” The coincidence of these results make it apparent that a change of some kind takes place in the neighbourhood of 1,400 km., or rather less than a quarter of the radius, from the surface, but it is equally clear that it is not a change of state, for both here and at greater depths the two forms of simple mass waves continue to be propagated at about the same relative rates as is demanded by theory. The change indicated is rather of chemical composition than of physical constitution, and in discussing this it is necessary to hark back. There is a considerable body of evidence, principally astronomical, though partly also geological, which goes to show that the central portion of the earth is composed of metal, principally iron, surrounded by a sheath of stony material. In part this deduction is reached from spectroscopic analysis of the sun and stars, in part from the composition of meteorites, which, whether regarded as the fragments of older worlds, or as the material from which worlds are built up, may be regarded as fair samples of the composition of our earth, and in.part from certain geological observations which indicate that deep down in the earth masses of metallic iron are associated with the ? Not yet published in full; for an abstract see Nature, November 21, 1918, p. 239. - * In this connexion it is noteworthy that just a year ago Dr. G. W. Walker announced his conclusion that many of the earthquakes which give rise to long distance records originate at about this depth (Brit. Assoc. Rep., 1917). The conclusion cannot be regarded as fully established, and there are some difficulties in the way of its acceptance, but it is an important and interesting suggestion, which must receive serious consideration, with the reservation that the origin is jot of the earthquake proper but of the bathyseism, of which the surface quake, which is felt and does damage, is a secondary result (see Quart. Journ. Geol. Soc., Ixy, p. 14, 1909). R. D, Oldham—The Intervor of the Earth. 25 stony matter of the onter layers. This hypothesis was mathemati- cally investigated by Professor S. Wiechert in 1897,' who found that, within permissible variations, the earth might be regarded as composed of a central core of density about 8 and an outer sheath of density about 3, the dimension of the core being from about three-quarters to less than four-fifths of the radius of the earth, according to the actual densities adopted, and that such an earth would satisfy the known conditions of mean density, as well as of precession and mutation. On the latter I can offer no opinion or criticism ; the former is easy of veritication, the densities are about right for the stony casing and the mainly iron core, allowing for the effects of pressure and compression, so that the hypothesis may be accepted as at least a possible one, and it is noteworthy that the limit of the two parts of the earth le just where the earthquake records indicate a change in composition, unaccompanied by change in state, of the material of which the earth is composed. There remains the central part of the earth, penetrated by wave paths emerging beyond 120° from the epicentre. In 1906 it was still doubtful whether the so-called second phase at these distances represented the much delayed distortional waves, travelling by a direct path, or was of a different character. In Professor Wiechert’s paper, already referred to, the slowing down of the rate of transmission, at depths below a little more than half the radius, was recognized, but the second phase was accepted without question as representing the same phenomenon as at distances of 100° and less, and this has remained the interpetation accepted by the Gottingen school, up to the latest publication which has reached us. In this country the trend of thought has been different; the first noteworthy landmark was the demonstration by Dr. G. W. Walker that what was recorded as the second phase at these great distances synchronized with the time at which waves reflected at, or near, the surface of the earth would reach the place of record,? and this seems still the most probable interpretation. Lately Professor H. H. Turner has attacked the same problem and, in the latest reports of the British Association and the Shide Bulletins, has shown, by statistical methods, that the so-called second phase at distances beyond the limit of 120° must be a different phenomenon from the second phase at lesser distances. Meanwhile, by an entirely different path, I had myself arrived at a similar conclusion; the examination of records of instruments of the type generally used in Italy, which give the second phase in an exceptionally clearly marked and conspicuous manner, showed that the so-called second phase at very long distances was of a different type altogether, and a few years ago I was able to examine some of the records of the Galitzin instrument at Mskdalemuir, which gave just the same result. The typical second phase, when well developed, shows a distinct commencement, a well-marked maximum and a less rapid dying out; it is, in fact, patently the record of a single group of waves of one character and 1 Gottingen Nachrichten, 1897, pp. 221-43. 2 Modern Seismology, 1913. 26 R. D. Oldham—The Interior of the Harth. form. At long distances, on the contrary, the commencement is more gradual; there is no well-marked maximum, but two or more succeeding each other, and the record bears the impress of being due to the successive arrival of more than one group of waves, just the appearance, in fact, which would be anticipated from Dr. Walker’s interpretation. Taking all this into consideration it is not possible to accept the supposed second phase at distances beyond 120° as being identical in character with the feature which is so well marked at lesser distances, and in these very long distance records nothing can be recognized which may be identified as the arrival of condensational wayes travelling bya direct path from the origin; if present they are much reduced in intensity and delayed in arrival. Hence we may conclude that the wave paths which penetrate deeper than the outer limits of a central nucleus, extending to something less than half the radius of the earth from the centre, encounter a material which is devoid of rigidity even against stresses of only a few seconds’ duration. A similar conclusion seems to have been reached by Mr. Harold Jeffreys, if I understand him aright, as the result of a mathematical investigation of the viscosity of the earth,'! based on tidal deformation and the periodic variation of latitude, so that we have two entirely independent lines of research leading to the same conclusion. To sumaup, we have found that the interior of the earth is divided into three distinct regions, characterized by differences in the physical condition of the material. They are :— 1. An outer crust, of matter which is solid in every sense usually attaching to the word. Its thickness is comparatively insignificant, being little more than half a hundredth of the radius. Atits lower limit this passes rapidly into 2. A shell of about half to three-fifths of the radius in depth, consisting of matter to which neither the term solid nor fluid can be applied without introducing a connotation which is contradictory to some of its properties, for while highly rigid as against stresses of short duration, or even of duration measured by years, it is capable of indefinite yielding to stresses of small amount if of secular duration. At its lower limit this passes somewhat rapidly, but more gradually than at the outer limit, into 3. A central nucleus consisting of matter having little or no rigidity, even against stresses of very short duration. Here the material may be described as fluid, whether liquid or gas, without introducing any contradictory connotation. In composition, as distinct from constitution, the earth appears to consist of two parts; a central portion mainly metallic and principally iron, extending to somewhere between three-quarters and four-fifths of the radius, and an outer envelope composed of stony material. - Geologically, we have a twofold division, into the outer crust composed of material more or less similar, in composition and 1 Monthly Notices of R.A.S., May, 1917, p. 454. - LL. F. Spath—Notes on Ammonites. 27 constitution, to the surface rocks with which we are acquainted, and an inner core which difiers in one or both of these characters. Etymologically the word “geology” should apply equally to the study of both these regions, but, for convenience and from the limitation of the individual human mind, it is usually confined to the problems presented by the rocks composing the crust, while those of the deeper regions lie outside its scope. Sach, briefly, are the conclusions which may be drawn from the Sciences of terrestrial observation. The statement, I know, is in- complete and imperfect; some at least of the conclusions will doubtless be traversed and regarded as incompatible with the results - obtained from other lines of research, but in their main features of the threefold division of physical condition and the twofold division of chemical composition they seem to me so weil founded that the ' barden of proof lies with those who would traverse, rather than with those who are prepared to accept, them. V.—Nores on AMUMONITES. By L. F. Spatu, B.Se., F.G-.S. Ee IJ \HE following notes were compiled, for the most part, some years ago, but their publication in the present form suggested itself to the writer on the perusal (during a short “‘leave” from active service) of a number of recent papers on Ammonites, principally Professor Swinnerton and A. E. Trueman’s study of the ** Morphology and Development of the Ammonite Septum”.! The Main part of that inquiry is devoted to the development of the septum, iliustrated by successive “septal sections’’, and it is claimed that where sutural development cannot be worked ont, ‘‘septal sections” will to some extent serve as a substifute. The writer has no intention of discussing the usefulness of ‘‘sepial sections”; but some of the suggestions put forward, and conclusions arrived at, by the authors, as well as certain opinions, which they adopt from other workers on Ammonites, invite critical examination. Since, in the present paper, other recent work on the morphology and physiology oi the Ammonite septum and suture-line, not yet embodied in text- books, is also included, and since the writer ventures to put forward opinions that differ in many essentials from the views of both textbooks and other authors, it is met | that the paper may prove oi general interest. ~ Tae Forwaep Buiter or roe Szprem. Swinnerton and Trueman give interesting contoured plans of the second and of the adult septum of Dactylioczras commune, Sowerby sp., and graphs illustrating the average profile of these two septa, and restate that “‘on the whole the second septum tends to be concave rather than convex forwards” (p. 37), and that “‘it appears that the _ [adult] septum as a whole is convex forwards” (p. 32). Professor ? Quart. Journ. Geol. Soc., vol. ixxiii, pt. i, pp- 26-58, pls. ii-iv, 1917. 28 L. F. Spath—Notes on Ammonites. Blake’s suggestion is adopted, that this forward convexity of the later septa (so conspicuous only because the average section of an Ammonite happens to pass through the ventral and dorsal lobes) is evidence of pressure from behind the animal; and it is assumed that “in Ammonites the vigour of secretion may have been so great that the gas exerted sufficient pressure upon the soft mantle to make it bulge forward while the septum was being deposited” (p. 83). The influence of this pressure is referred to in connexion with the modification of the adult suture-line in Dactyloide, where among other ‘‘ageing’’ characters of the later suture-lines the authors mention the ‘‘ more intricate wrinkling of the minor details”. They state (p. 39), ‘‘This complexity is strongly suggestive of the wrinkling of a collapsing or flaccid bladder, as opposed to the simpler and more turgid outlines of the folioles in earlier septa, and suggests a diminution in the vigour of gas-secretion in the declining period of life.’ The association of complexity with decline may seem contradictory ; for the authors, speaking phylogenetically, say (p. 51) “during retrogression this fringe [of complicated frilling | is gradually lost’’. This complexity is not so apparent, however, as the other ‘‘ageing”’ characters mentioned, namely the ‘‘ decrease in the antero-posterior range of the lobes and saddles”’ or ‘‘ crumbling down of the apices of the saddles to approximately the same plane’, and the ‘‘swinging forward of the umbilical portion of the suture-line”’ (p. 39). Following S. 8. Buckman, the authors consider the Dactyliocerates to be “evidently a decadent offshoot of Celoceras’’, though to the writer neither the decadence of this most flourishing family nor the derivation from the Carixian pettos-group, to which the genus Celoceras must be restricted, is evident. They see in them ‘‘the phenomena which characterize the first stages in the simplification of the suture-line, a simplification that is carried to such extremes in Cretaceous Ammonites”? (p. 40). CoRRELATION OF SUTURE-LINE AND WHORL-SHAPE. Attention must be drawn in this connexion to the close relation- ship that exists between the suture-line and the shape of the whorl. In the Dactyloide the tendency is towards loosely coiled, more or less cylindrical whorls, and in the evolution from a cadicone ancestor, through depressed whorls, to the slightly involute shell of the Dactylioceras figured by Swinnerton & Trueman, the suture-line would adapt itself to the altered whorl-shape. Zittel! stated: ‘‘ When the whorls are circular one observes ordinarily only a few lobes, and in that case they are of nearly equal dimensions (Lytoceras); upon a wide ventral area the external lobe and external saddle acquire considerable dimensions; the flatter the sides are and the thinner the ventral part, the larger the size of the lateral lobes and lateral saddles, and the more numerous the auxiliary lobes.” Pfaff? mentions that ‘compressed forms would show the greatest differentiation of their suture-lines in the lateral region and in the ' Handbuch d. Pal., vol. i, 2, pp. 332, ete., 1881-5. 2 “*Form u. Bau d. Ammon.-Sept., etc.’’: Jahresb. Niedersichs. Geol. Ver., vol. iv, pp. 221-2, 1911. ‘ L. F. Spath—Notes on Ammonites, 29 principal lobe; depressed forms on the other hand externally and internally. Again, as during growth the septal gurface increases at the relatively quickest rate on the external side, differentiation must begin here” On Scamination of the three types of Ammonites chosen by Swinnerton & ‘Trueman, it is found that in TZragophylloceras. Loscombi! with wide lateral areas, the first lateral lobe and first lateral saddle show the greatest differentiation; and in the depressed Spheroceras Brongniarti it is the external saddle. In the Dactyliocerate suture-lines figured by the authors on p. 89 the widest-ventered form (fig. 4) has the external saddle strongly developed, and it has already been remarked that there is a tendency to equalize the size of the saddles on the adoption of a more cylindrical whorl. It should be pointed out, however, that there are what may be called family peculiarities that modify the suture-elements in certain cases. They are of value in tracing the affinities of homoeomorphs, such as the perfectly similar oxycones that appear at so many horizons. he Triassic Antomoceras denudatum, Mojsisovics, and the Cretaceous Garnierta e.g. had been put into the strictly Lower Liassic genus Oxrynoticeras by different authors. Although, in the mechanical adjustment to a wider side, either by the spreading-out of the lateral lobes and saddles or by the addition of auxiliary or adventitious elements,’ similar suture-lines may result in different stocks, yet the modified shells can generally be referred to their ancestral stock by means of some retained family characteristic. Again, the genera Jlacrocephalites, Cadoceras, Pachyceras, Torn- quistes, and ELrymnoceras, with wide ventral areas, all have a very large external saddle. In Chamoussetia, a smooth and keeled descendant of the Cadoceras stock, what may be considered the natural adjustment of the suture-line to this type of shell is shown; yet in the later keeled Quenstedticeras and Cardioceras the suture- line at first still is more or less similar to that of the fat ancestral forms. This may partly be retention of the family character or hastening of the development of the keel; but it may be assumed that ornament and other mechanical expedients for the increase of the solidity of the shell also influence the septal edge. This may account for the changing width of the external saddle in Macrocephalites and Tornquistes to which R. Douvillé® has drawn attention. Zragophylloceras ibee, with strong ornament, has a simplified suture-line as compared with the smooth Phyllocerates* of _ 1 The specimen used by Swinnerton and Trueman for their series of septal sections (fig. 13 on p. 46) shows the small terminal leaflets of the ibex group. 2 Pictet (Traité de Paléont., p. 669) pointed out already in 1854 that the inflated “* varieties ’’ of a species often differed from the compressed ones in the number of the accessory lobes, and that modification of the umbilicus produced the same result. 3 ‘*Htude sur les Cardioceratidés de Dives, etc.’?: Mém. No. 45, Soc. Géol. France, Pal., i, 19, fase. 2, p. 14. + Additional work on the various features of the suture-line has demonstrated to the writer the impossibility of basing the separation of genera which other 30 LL. FP. Spath—Notes on Ammonites. the ancestral stock. In Saculites again, where, theoretically, the suture-elements should be equal, there is a fair amount of variation, caused probably by the differences in cross-section, ornament, and thickness. It may be added here that certain Lower Aptian developments of the Upper Barremian Leptoceras (trispinosum-group) show how with the gradual straightening out of the shell the suture-elements become more nearly equal. One such form is e.g. ‘ Hamites” nodosus, v. Koenen,' which, of course, has nothing to do with the Albian genus Hamites, just as ‘‘ Bochianites” undulatus, v. Koenen,? cannot be attached to Bochianites, a homceomorphous development of an earlier perisphinctoid Hoplitid. The suture-line of these hoplitid Crioceratids then assumes the aspect of that of the lytoceratid Macroscaphitide, and the distinction between these two important families becomes very difficult. CorreLaTION oF Svurure-LineE, ATTACHMENT TO SHELL AND MopsE - oF Lire. Another factor has to be considered here. It appears probable that in Ammonites, as in the recent Wauéilus, the shell-muscie could easily be detached from the shell when the animal moved forward a certain space to form a fresh chamber, and that, as there would have been considerable risk of the shell falling away from its inhabitant, the folded posterior portion of the Ammonite animal with its lobes and saddles afforded the means of holding on, a function performed in WVautilus by the strong central siphuncle.* When a stock lke #aculites, in addition to its tendency to equalize the suture-elements of its straight shell, also shows simplification of the suture-line, it may be assumed that it represents an adaptation to a benthonic mode of life which its form alone would indicate. For Lytoceras itself, ‘‘often as thin as paper and clear as glass, with feeble ornament, i.e. characters that clearly remind one of adaptive forms of nectonic Gastropods of the high seas, Atlanta,’ * and the delicate and smooth shells of Phylloceratide and Arcestide do not generally show simplification of the suture-line. In the latter, and also in most oxynote shells, so admirably adapted for an actively swimming mode of existence, the need for secure attachment of the animal to its shell was probably greater than in benthonie crawlers. In those one-sided Ammonites of the Lias, called Zurrilites by VOrbigny, which, unhke Buckman® I would consider to be such characters and especially geological occurrence would appear to connect (in this case Tragophylloceras and Rhacophyllites) on the comparatively in- significant difference in the endings-of the external saddle. 1 ‘“* Ammonitiden des Norddeutschen Neocom.’’?: Abh. Preuss. Geol. Landesanstalt, N.F., Heft xxiv, p. 393, pl. xxxy, fig. 13. 2 Tbid., p. 398, pl. liii, figs. 11, 18, 14. * See E. A. Smith, ‘‘ Note on the Pearly Nautilus,’? Journ. Conch., Oct., 1887; and Foord, Cat. Foss. Ceph. Brit. Mus. (Nat. Hist.), pt. i, pp. xi, xii, 188s. * Diener, ‘‘ Lebensweise u. Verbreitung d. Ammoniten’’: N. Jahrb. Miner., ete., ii, pp. 67-89, 1912. > **Vererbunesgesetze und ihre Anwendung auf den Menschen *’ : Darwinist. Schriften, I, vol. xviii, p. 22 (214), 1893. L. F. Spath—Notes on Anvmonites. dl adaptations to a benthonic existence, the suture-line is not affected. But in such aberrant types as Cochloceras, Rhabdoceras, and Choristoceras, where the reduction of the septal edges to great simplicity is accompanied by modifications of the coiling, the adaptation to a different mode of life can scarcely be doubted. Professor J. P. Smith' calls these ‘‘ reversionary’’ types; but if the reduction of the suture-line and uncoiling were reversions to a primitive type. they should be preservative. ‘The writer would also look upon (WMeoptychius Christo, Beaudouin, sp., Popanites patturatensis, Greppin, sp., and similar forms as aberrant, benthonic types. ‘¢PrynocERontic”? SurvuRE-LINES. CoRRELATION oF SUTURE-LINE AND ORNAMENT. With regard to the ‘‘reduction” of the suture-line, distinction has to be made between such simplification as is shown in many individual Ammonites, where the last few septa may be simpler and be associated with an (equally sporadical) approximation. This is a growth-phenomenon of the individual. The formation of septa probably ceased when maturity was reached and the character does not become ‘‘phylogerontic’”’; for the stock muy continue to _ elaborate its suture-line. Or, again, in the broad stream of develop- ment of a whole family, one branch, under local influences or owing to a tendency to diversity, may modify or simplify its suture-line. It is clear that if whorl-shape and suture-line (and of course also the other characters of the shell) are as closely interconnected as the writer believes, a form like Hudlestonia must adapt the suture-line of its probable ancestor Phlyscogrammoceras to an oxynote shell, with wide lateral area, according to the general rules mentioned above. Similar modification is shown in Staufenia and Clydoniceras.” The latter, a local development * of the Bathonian Oppelia, does not so much ‘‘ reduce” its suture-line as, rather, take on a specialized type that resembles certain ‘‘ Pseudoceratites’’, with an increased number of elements, but less frilling. It is to be noted that the families themselves (Ludwigine and Oppelide) are not affected. In Proplanulites and Pictonia* the reduction is shown in the shortening of the saddles and lobes and the decreased complication 1 In Zittel-Eastman, Text-book of Pal., 2nd ed., vol. i, p. 673, 1913. 2 Menzel, Zeitschr. Deutsch. Geol. Ges., vol. liv, p. 90, 1902. * Blake (in Great Oolite Mollusca, Mon. Pal. Soc. vol.), from the occurrence of this genus in the southern part only of the Cornbrash outcrop in England, concluded that it was dependent on the presence of the Great Oolite Series below, of whose fauna it was a relic. Compared with the almost universal distribution of the genus Macrocephalites, this restriction of Clydoniceras is interesting and shows that, like many modern marine organisms, certain Ammonite genera were undoubtedly strictly limited in their horizontal distribution. In aberrant or benthonic types, of course, like the Oxynoticeras derivative ‘* Zigoceras’’ Slatteri, Wright, or Nipponvites, the local restriction . might be expected, more than in active swimmers. * Tornquist, ‘‘Proplanuliten a. d. Westeuropdischen Jura’’: Zeit. Deutsch. Geo]. Ges., vol. xlvi, 1894; also ‘‘Die degenerierten Perisphinctiden d. Kimmeridge vy. Le Havre’’: Abh. Schweiz. Pal. Ges., vol. xxiii, 1896. 32 L. F. Spath—Notes on Ammonites. oftheirmargins. Withregard to Prctonie, Tornquist’ stated: ‘‘ We get the impression that they are Ammonites that have resulted from different groups of normal Ammonites, through general degeneration affecting them under local influences during Kimmeridgian times.’’ It must be repeated here that development or loss of strengthening ornament on the shell would affect the suture-line as much as change of whorl-shape. For e.g. in Pictonia cymadoce the ornament may be more ‘‘reduced”’ than the suture-line in one specimen, and in another the suture-line more than the ornament.” Adaptation to a Nautiloid, or less exclusively swimming mode of life,? might have taken place in Mrechiella, which is also often one- sided and which shows the modification of its ancestral AHuldoceras suture-line in its ontogeny. And the oxycones of Hudlestonia and Stanfenia were better adapted to an actively swimming existence than their Grammoceratan and Ludwigian ancestors. With Renz and J. yon Pia* the writer would be inclined to favour the theory of adaptation, therefore, even if the special mode of adaptation be not quite clear in some cases, rather than speak of decline of vitality or phylogenetic degeneration. WaotesaLeE Puyteric ‘ Catacenesis’’. This applies, of course, also to the modification of the suture-line in the Cretaceous Pseudoceratites, which, however, is on a different scale, and whigh has been explained as a phenomenon coincident with the approaching end of the whole race of Ammonites. Walther ° had stated: ‘‘ Ammonites, after dominating the seas through three long periods and nearing their end, show in all groups such clear symptoms of abnormal growth, such evident signs of senile degeneration, that their extinction through a kind of senile decay seems to us inevitable.” As far as it affected the suture-line, this “‘degeneration’’ produced ‘‘forms which remind one of Triassic Ceratites and even of certain Palgzozoic Goniatites”.® Indeed, Neolobites Vibrayanus (dV Orbigny) and DMetatissotia Ewaldi (v. Buch) e.g. had been put into the genus Ceratites by d’Orbigny and even into Goniatites by Pictet. Just as in the modification of the shell, only certain lineages were affected, however, and these differently and at different horizons. But this going back, as it were, along the line followed in the evolution of the group from Goniatites through Ceratites to Ammonites, however incomplete, fitted into the representation of Ammonite phylogeny as a series of cycles ‘‘ which 1 Op. cit., p. 42. 2 Thid., p. 39. 3 Diener (‘‘Lebensweise u. Verbreitune d. Ammoniten’’: N. Jahrb. Miner., etc., ii, p. 69, 1912) says that Nawtilws lives chiefly crawling, but can swim well and quickly, and has also been found attached to the bottom, which ‘“ shows that its present mode of life is little stable yet’’. Diener, therefore, does not agree with Dollo (‘‘ Les Cephalop. adaptés 4 la vie nect. second. et & la vie benthique tertiaire’’: Zool. Jb. Spengel. Festschr., Suppl., xv, 1, p. 111, 1912), who ascribes a primarily benthonic mode of life to Nawtilus, the ““type of the ancient Cephalopod with functional, external shell’’. 4 N. Jahrb. Miner., etc., ii, p. 169, 1913 (in review of Renz). ° Geschichte der Erde und des Lebens, 1908, p. 451. 6 Haug, Traité de Géologie, vol. ii, fasc. ii, p. 1166, 1908-11. L. F. Spath—Notes on Ammonites. 33 is in direct contradiction to a causal explanation of their develop- ment’’’, as it conveys the impression of an inborn racial necessity of a predestined character. The ceratitic suture is one type of line that may recur in the Ammonoid history, just as the same types of ornament appear repeatedly between the Devonian and the Cretaceous, owing to the limited possibilities of variation in each character. Hyatt? had considered ‘‘ the multiplication of the principal inflections in Pseudoceratites of the Cretaceous”’ to be necessitated ‘‘in compensa- tion for the suppression of marginals”. The pseudoceratitic suture- line also is not by any means always ‘“‘reduced”’, so that its function as a means of attachment of the animal to its shell is not impaired. A form like Indoceras baluchistanense, Noetling, with 37 lobes and 38 saddles or 75 elements in its suture-line, recalls the acme of specialization among Triassic Ammonites. According to its author, this youngest of all Ammonite genera, the well-formed specimens of which occur abundantly in beds that pass without break or un- conformity into the Hocene, shows no geratologous characters. Prrtopic Kvotution anp UnstasBte ENVIRONMENT. | It might be suggested that in the evolution of the suture-line “periodicity of elaboration’? occurs such as is claimed for other features and as is observed in the Cretaceous Asteroidea by Spencer,* and that after a period of ‘‘catagenesis”’ affecting the Pseudoceratites in general, there was renewed elaboration in Lybicoceras or Indoceras. There can be no doubt, however, that Pseudoceratites represent a number of independent developments of different normal Ammonites, just as the tendency to attain dissimilarity in form, in response to differences of environment, is shown in many different stocks. This ranges from the Hauterivian Crioceras to the Maestrichtian Bostrychoceras and culminates (morphologically) in the incredible tangle of Wipponites; but their relationship is confined to a similar benthonic mode of life. Strong adaptive radiation, such as is generally shown in the young stages of a stock, occurs repeatedly during Cretaceous, as in previous, times. ‘‘Changes of structure and diversity of life” are probably ‘‘ directly related to the physical conditions of habitat’’,. and the ‘stability of organic forms is in direct ratio to the stability of the conditions of existence’’.* As mutation was so continuous during Cretaceous times, the conditions of existence in so far as they concerned the Ammonites cannot have been stable. EXTINCTION AND Environment. LimE SECRETION. The writer favours the view that the disappearance of Ammonites was not due to inherent phylogenetic relations and inability to 1 J. y. Pia, N. Jahrb. Miner., etc., i, p. 169, 1914, in review of Mr..-Buckman’s Yorkshire Type Ammonites. 2 In Zittel-Eastman, Text-book of Pal., vol. i, p. 544, 1900. 3 ‘*The Evolution of the Cretaceous Asteroidea ’’: Phil. Trans. Roy. Soe. Lond., ser. B, vol. 204, pp. 156-7, 1913. 4 Joel A. Allen, “‘ The Influence of Physical Conditions in the Genesis of Species’’: Smithson. Inst. Ann. Rep., 1905, p. 401. DECADE VI.—VOL. VI.—NO. I. 3 34 LL. EF. Spath—WNotes on Ammovnites. modify, but to physical causes. To quote Diener, ‘‘ A flourishing family like Lytoceratide, which during the whole of the Cretaceous period produced a number of irregular forms and which, itself, persisted later than these irregular forms, cannot by any means be considered degenerate.” One of the most reduced types, with ‘‘goniatitic’’ suture, is Flickia simplex, Pervinquieére,* which is a morphic equivalent of the Triassic Lecanites. Whether this is regarded as a local modification of Neolobites or an independent benthonic dwarf development, its Cenomanian age is of no significance; for the writer has seen a specimen in the British Museum (Natural History) with a similar entire suture-line (at a diameter of 12mm.) from the Caloceras bed of the Hettangian that looked like a Paleozoic Pronorites. The diminutive size of lickia, of course,. suggests unfavourable surroundings; but it appears that in the dwarf faun of Morade Ebro* and other localities the suture-line is little affected. It is conceivable that thickening of the shell may take place in a series under local influences, i.e. increased lime-secretion, shallowing of the sea, or alteration of the incoming sediment in a more or less confined region. ‘The simplification of the suture-line of Metoicoceras* (Turonian Jnoceramus facies) as compared with that of the Cenomanian Acanthocerates may be due to such environ- mental changes, affecting metabolism generally, and thus the secretion of lime; and this might also apply to the Kimmeridgian Pictoni@ already mentioned, where the suture-line may be more reduced than the ornament in one specimen, and the ornament more than the suture in another. With regard to the simplification in individual Ammonites referred to above, this follows on a continuous elaboration to often great complexity, and is associated occasionally with approximation of the last few septa, which association alone would account for the simplification of the edge. Or, again, they may be thickened, like the last septum of the recent autilus pompilius or certain Liassic Nauti, and thus make up in the enlarging of the adhering surface for what strength was lost in the simplification. No observations seem to have been made on this point, however. It will be noted that in Psiloceras and other Ammonites the last few suture-lines show what Swinnerton and Trueman in Dactylio- ceras call ‘‘simpler and more turgid outlines of the folioles’’, as } Op. cit., 1912, p. 79. Frech, ‘‘ Neue Cephalopoden a. d. Buchensteiner, Wengener, and Raibler Schichten d. siidl. Bakony’’: Res. Wiss. Erf. Balatonsees. Pal. Anh. z. Teilid. Bd. i, p. 72 (quoted by Diener), expresses similar views. 2 The local restriction and numerical insignificance of this ‘‘ goniatitie’’ form compared with its normal contemporaries and the flourishing Scaphites and Turrilites shows the incompleteness of the ‘‘ cycle’’: > A. Wurm, ‘‘ Beitr. Kenntn. Iberisch-Balearischen Triasprovinz*’: Verh. Naturhist.-mediz. Ver. Heidelberg, vol. xii, 4, 1913. This fauna is even more reduced than that of St. Cassian, which it resembles. 4 M. Leriche, ‘‘ Sur la présence du genre Metoicoceras, Hyatt, dans la Craie du Nord de la France, etc.’?: Ann. Soc. Géol. Nord, vol. xxxiv, pp. 120-4, 1905. Reviews—The Brachiopods of Scania. 35 opposed to their ‘‘ageing” character of more intricate wrinkling, assumed to be due to diminished gas-pressure. Psiloceras shows not only complex suture-lines with dependent inner portions at first and simpler ones with ascending auxiliaries at the end, but also often asymmetry of the suture-line, and approximation of the last few septa, and these features will be considered in the following parts of this paper. (To be continued.) RAVI WwWSsS- f J.—On rue Bracarorop Suares or Scania. Om Sxanes Bracwiopopskirrer. By Gustav T. ‘TRoxEpsson. Meddelande fran Lunds Geologiska Faltklubb, ser. B, Nr. 10, TOTS: 'H\HE memoir by Dr. Troedsson on the Brachiopodskiffer of Scania is of importance to students of the Ordovician strata, and must be consulted by anyone who proposes to work at the Ashgillian faunas. These Scanian beds have long been recognized as the general equivalents of the Ashgill Shales of the North of England, which they resemble in respect of lithological characters, fauna, and stratigraphical position. The memoir is divided into two parts, the first stratigraphical, the second paleontological. In the first part the author gives a historical sketch, which is followed by details of the succession in various localities, and by a comparison of the beds with those of other areas. The second part is concerned with a description of the species. The fauna consists largely of species which ascend from the Staurocephalus beds, but is much poorer in species than are those beds. The author, however, has made a noteworthy addition to the fauna; only five species were known before, whereas he gives a list of forty-six forms. Although the beds as a whole are equivalent to the Ashgill Shales, it is possible that they contain earlier strata than the lowest part of those shales, for Dr. Troedsson divides them into two sub-zones, the lower (that of Dalmanites eucentrus) being distinguished also by the abundance of Ostracods. This is a characteristic feature of a calcareous band with abundant D. eucentrus below the Ashgill Shales, which has been bracketed with the underlying Stawrocephalus beds, and this calcareous band may represent the lowest Brachiopodskiffer, though differing in lithological character. The summit of the Brachiopodskiffer is probably older than the uppermost Ashgill Shales, for the author separates from the former a zone of Chimacograptus scalaris, which, like the highest Ashgill Shales, is succeeded by the beds of the zone of Diplograptus acuminatus. The zone of C. scalaris is probably only of local value. C. normals is recorded in England in beds below the Ashgill Shales, and is abundant inthe succeeding Valentian rocks, and although it has not yet been found in the shales themselves it must have lived at the time of their formation. 36 Reviews—Santo Domingo Fossils. In the paleontological part of the memoir the author gives the distinguishing characters between Dalmanites eucentrus and D. mucronatus, concerning which there has been so much confusion. The former was described by Angelin from the Brachiopodskiffer of Rostanga, in Scania, and the same author described the latter from the Brachiopodskiffer of Ostrogothia, where it occurs in beds of a higher horizon than the highest beds of that name in Scania, in rocks which contain a Valentian fauna. These two species have been stated to be identical, and it is satisfactory to have a description . of their differences. It must be noted, however, that in Scania the two forms occur in the Ordovician Brachiopodskiffer, though it is doubtful whether D. eucentrus has ever been discovered in strata of Valentian age. A new Dalmanites (D. Ktert) is described from the Norwegian Brachiopodskiffer, and stated ‘‘to be allied to D. obtusicaudatus, Salt., from the Upper Caradoc of England”’. The latter species is really of. Lower Ludlow age, and the Norwegian form more closely resembles D. Roberts, described by Dr. Cowper Reed, from the Ashgillian strata of Hover onbyest (Gron. Mac., Dec. V, Vol. I, Pp: 106, 1904). An English summary ‘of the two parts is given in the concluding portion of the memoir, which is illustrated by many plans and sections, and by two plates of fossils and illustrations of others in the text. . J. E. M. I1.—Santo Domtneo Fossits. Santo Domineo Type Sections anp Fossits. By Cartorra Joagurna Mavry. Bulletins of American Paleontology, 1917, vol. y, No. 29, pt. i, Mollusca, pp. 165-415 (1-251), pls. xxix—lxy (iii-xxxix); No. 30, pt. ii, Stratigraphy, pp. 416-59 (1-48), with sketch-map of expedition, views of country, geological sections, correlation table, and 36 plates of molluscan figures. FE\HE authoress is beetle well known to geologists for her memoirs on “Some New Oligocene Shells from Florida” and ‘The Paleontology of Trinidad’, She was fortunate in being selected as a member of a small expedition to the Island of Santo Domingo, in 1916, for the furtherance of geological research, which was carried out under the auspices of the ‘‘Sarah Berliner Foundation”. In the volume before us comprehensive details are given of the many sections visited on that occasion, from which numerous fossils were obtained, all having been zonally collected and properly localized. These fossils comprised a considerable fauna belonging to several groups of the animal kingdom, although the Mollusca form the larger series and contained over 800 species, many of them being described as new to science. The descriptions of the Mollusca, accompanied by more than 500 illustrations, form the first and largest part of this work, while the second part relates entirely to stratigraphy. The writer refers gratefully to the pioneer work of Colonel Heneken, who nearly seventy years ago surveyed the same Reviews—Santo Domingo Fossils. 37 country and made valuable collections of fossils, which he sent to the Geological Society of London, but which have been since transferred to the British Museum. Heneken described the geological features of the region, whilst the molluscan remains were studied by G. B. Sowerby and J. Carrick Moore, and the corals by W. Lonsdale, the combined results forming notable memoirs in the Quarterly Journal of the Geological Society for 1850 and 1853. Both Moore and Sowerby recognized that some of the shells exhibited Pacific affinities, although more often a Miocene facies Was apparent with resemblances to those found in the deposits of Bordeaux, Touraine, and Malta, as well as to those of similarly aged beds in the more eastern parts of the United States. At a later date R. J. L. Guppy and W. H. Gabb contributed largely to our knowledge of this subject, and supported the Miocene age for the fossiliferous rocks as first enunciated by Heneken and his colleagues. Like Heneken’s collections most of the writer’s fossils were obtained from the northern part of the island, in the Yaqui Valley. Among the Tertiary clays and limestones of that district, three well-defined formations, differing in their molluscan faunas, have been determined as the Sconsia levigata, the Aphera islacolonis; and the Orthaulax inornatus, the last being the oldest. ‘he first named is recognized as belonging to the Burdigalian stage of the Middle Miocene of Europe, the second is included in the Upper Aquitanian or Lower Miocene, and the third is regarded as Rupelian or Upper Oligocene. “The Gatun beds of Panama, together with the Alum Bluff and Oak Grove deposits of Florida, are said to be synchronous with the Sconsia levigata formation, whilst the Bowden beds of Jamaica, with a mixed fauna, are scheduled as belonging to both the Sconsia levigata and the Aphera islacolonis formations, the latter also ‘ineluding the Chipola River marls of Florida. The Orthaulax imornatus formation includes the Tampa silex beds of Florida. Further, it is urged that this fossil fauna of the Yaqui Valley is not only most closely allied to that of the Bowden beds of Jamaica, but exhibits affinities with that characterizing deposits in Cumana, Trinidad, and Martinique. It will be readily seen from this brief survey of Dr. Manry’s book that all the best methods of investigation have been utilized in its preparation. Instead of being satisfied as to the Miocene age of the fossils under which they had hitherto been generally recognized, her employment of the zonal system of collecting, and a careful classification of the numerous molluscan remains obtained, have facilitated the recognition of some important faunal distinctions, and so enabled the writer to divide these Miocene and: Oligocene rocks into certain stages which are in eee eee with the European standard of stratigraphy. This is a valuable and an authoritative memoir, and will be greatly welcomed by geologists and paleoconchologists alike, as a history of the Tertiary sequence in this and neighbouring parts of the Western Hemisphere, founded upon molluscan evidence. iter Bre- Nis 38 Reviews—Concretions, Auckland Harbour. I11.—Concretions IN tHE RECENT SEDIMENTS OF THE AUCKLAND Haxzpour, New Zeatanp. By J. A. Bartrum. Trans. New Zealand Inst., vol. xlix, pp. 425-8, with 1 plate, 1916. URING the dredging operations of Auckland Harbour a number of caleareous concretions were brought up by the pumps. These consisted of nodular masses of hard, compact limestone, varying in size from }in. up to 6 inches or more in diameter. They enclose recent shells of all kinds, some of which seem to have served as nuclei for the precipitation of the calcium carbonate, and also diatoms and quartz grains. They give no indication of having been derived from any previously consolidated rock, and seem to have been formed contemporaneously with the harbour silt, by precipitation of calcium carbonate from the sea-water. This precipitation was probably occasioned by the decay of organic matter in the epidermis of molluscs, or the hard parts of crabs which form the nuclei of the concretions. W.. BiWe IV.—Tae Jurassic [ronsrones or tHE Unitep Kinepom, KconomicaLuy CONSIDERED. By F. H. Harca. Journ. Iron and Steel Inst., vol. xevii, pp. 71—120. AvreracGeE AWNALYsEs oF British JROoN-onES AND JRONSTONES PropuceD IN 1917-18. By F. H. Harcu. Published by the Ministry of Munitions. 12 pp. 1918. N important part of the work of facilitating the supply of munitions of war lies in the proper development and economical utilization of raw materials. In the case of iron-ores the Ministry was fortunate in securing the services of Dr. Hatch to assist in supervising these matters. Besides the actual mining of the ores it was found that other subjects were also in need of attention, such for example as ‘‘ blending’”’ of ores of varying composition to produce a standard product, methods of calcining, and economies in transport. All of these are briefly touched on in the first of these memoirs, but the greater part of it is taken up with a description of the actual occurrences and mining of the Jurassic ironstones of the British - Isles, with analyses and statistics of production. The Jurassic iron-ores occur at three principal horizons, namely, in the Lower Lias in Lincolnshire, in the Middle Lias in Cleveland, Leicestershire, and Oxfordshire, and in the Inferior Oolite in Northamptonshire. Expressed in percentages of the Jurassic out- put the Lower Lias was responsible in 1917 for 22:3 per cent, the Middle Lias for 51 per cent, and the Inferior Oolite for 26:2 per cent. The Upper Lias ore of Raasay amounted only to 65,985 tons or 0°5 per cent of the total. The Corallian ores of Westbury are not now worked. The most striking recent development is in connexion with the Middle Lias ores of Oxfordshire, which are now being exploited on a very large scale, largely for the supply of furnaces in South Wales. The total output of this county in 1917 was 434,435 tons, with an average iron content of 24 per cent. Reviews—Ancient Buried Forest. 39 The second publication above quoted contains some new and interesting material. It is mainly taken up by a tabulation of analyses of British iron-ores mined in 1917, but the brief introduction of two pages gives in a very condensed form a summary of the statistics of production for 1917. Of 15,028,000 tons mined in that year 89°5 per cent was phosphoric and of iow iron-content, the remainder being high-grade hematite ore with low phosphorus, obtained almost entirely from Cumberland and Lancashire. The phosphoric ores derived from the Jurassic formation make up 80°6 per cent of the total productione the rest coming from the Coal-measures, with an almost negligib|1 amount (under 1 per cent) from other sources. These facts may be summarized as follows :— per cent. tons. Lias . j F : 59-5 8,947,520 Inferior Oolite . y 21-1 3,169,110 Coal-measures . é 8-1 1,194,882 Miscellaneous . - + 0-8 129,961 Hematite ores . : 10:5 1,586,429 100-0 15,027,902 Thus it appears that at the present time the Jurassic System is the dominant factor in the iron-ore industry of this country, while the one-time importance of the Carboniferous is rapidly waning. It is, perhaps worth bearing in mind that it was the introduction of the basic Bessemer process that rendered possible the utilization of these low-grade ores, both in Britain and in Lorraine. Without this the cqurse of recent industrial development must have been very different. Fortunately the mining of the Jurassic ores of the Midlands is a very simple matter, being quarrying rather than mining, and the introduction of suitable machinery has done much to stimulate large and economical production in a time of labour shortage. Jiggadels 1k V.—An Ancrtenr Burtep Forest NEAR RiccarTon: Its Brsrine on THE Mopr or Formation oF THK CantrrBuRY Prains. By R. Seeient, M.Sc., F.G.S. Trans. New Zealand Inst., vol. xlix, pp. 361-4, with 1 plate, 1916. ee Canterbury Plains which form the eastern part of the South Island have been built up almost entirely by the alluvial cones brought down by the rivers from the western mountain chains. This deposition of alluvial gravel has been accompanied by a down- ward movement of the land, and timber is often found in boreholes as much as 450 feet below the surface. The stumps of the trees which formed the forest described in this paper were found in place on a bed of clay, under 12 feet of gravel, at a height of about 50 feet above the sea, in a pit near Riccarton. Some of the trunks were standing, but most of them had been snapped off very 40 Reports & Proceedings—Geological Society of London. low down. This fact, and the general relations of the clay and gravel in which they were found, suggest that the forest was destroyed by the flooding of the surface with gravel from the migrating cones of rejection, a process which may be seen still in operation in other parts of South Island. The roots were held firmly by the gravel so that the trunks could be snapped off leaving the stumps in place and undisturbed. This occurrence, therefore, is additional evidence in favour of the idea that the Canterbury Plains were formed almost entirely above water, from the gravel of the alluvial fans of rivers, and that the material was not deposited under the sea. REPORTS AND PROCHEDINGS. I.—Grotocicat Socorery oF Lonpon. November 20, 1918.—G. W. Lamplugh, F.R.S., President, in the Chair. The President referred with regret to the loss that the Society has sustained by the death of Miss Maude Seymour, on November 6 last, after a very short illness. He alluded to the high value of her services as an Assistant in the Library, and to her energetic assistance in the preparation of the ‘‘ List of Geological Literature’’. The following communication was read :— ‘““The Geology of the Meldon Valleys, near Okehampton, on the Northern Verge of Dartmoor.” By Richard Hansford Worth, M.Inst.C.E., F.G.S. The area dealt with lies between the London and South-Western main railway line, from a point a litte east of Meldon Viaduct to near Sourton, and the ridge of Dartmoor occupied by Black Tor, High Wilhays, Yes Tor, and West Mill Tor, being the greater part of the valley of the Redaven and a portion of the valley of the West Okement. The southern extreme of this area is occupied by the Dartmoor Granite, north of which are shales, in which occurs a patch of limestone, and these are intersected by numerous bands of igneous rock. The shales as a whole, with but slight local deviations, strike north-east and south-west and dip north-westwards, the mean angle of dip being about 50°. The sedimentary rocks are divisible into :— 1. An alumino-arenaceous series, extending from the granite northwards for a breadth of somewhat over half a mile. . A calcareous series, abruptly but conformably succeeding the last. . A limestone, which occurs a short distance south of the railway. . Radiolarian cherts a little above and a little below the horizon of the limestone. . An aluminous bed north of the railway. or H= Oo bo Reports & Proceedings—Geological Society of London, 41 Of these, (1) consists of impure grits, which, being well within the aureole surrounding the granite, have developed secondary mica, a little tourmaline, and small well-formed rutiles. In some places, at contacts with granitoid veins, andalusite is also found. (2) Consists mainly of porcellanites with beds of black chert-like rock. ‘The characteristic mineral of the porcellanites is wollastonite, but at contacts with the Meldon Aplite garnet, idocrase, scapolite, axinite, and lepidolite are also developed. (8) Shows little sign of metamorphic action. (4) Are cherts of the character already well known as occurring in the Lower Culm-measures, and described by the late Dr. G. J. Hinde & Mr. Howard Fox. (5) Is a dark-grey rock, almost black, the characteristic mineral of which is chiastolite. All these rocks succeed each other conformably, and there is no _ evidence of folding or repetition. In the sedimentary series planes of weakness have developed, the surface traces of which are broadly coincident with the strike, but which frequently lie counter to the dip. These planes have been more or less successfully invaded by at least three series of igneous rocks, the order of which, commencing with the earliest, is as follows :— 1. A felsite with phenocrysts of micropegmatite, and quartz which shows good rhombohedral cleavage. 2. A series, hereafter called the ‘‘ dark igneous rocks ”” 3. Granitoid veins, subdivided into— (1) The Meldon Aplite and its associates ; | (2) Fine-grained granite of the ordinary Dartmoor type. The evidence on which this chronology has been based seems fairly clear. The felsite with micropegmatite occurs as inclusions in the ‘‘dark igneous rocks’. The ‘‘dark igneous rocks’”’ occur as ‘inclusions in the Meldon Aplite. The Meldon Aplite occurs as veins in the ‘‘dark igneous rocks’’. No evidence is available as to the relative age of the Meldon Aplite and the granite veins. A marked feature of the ‘‘dark igneous” rocks is that they are locally agglomeratic; as such they have been identified as meta- morphosed tuffs. But, on the other hand, every exposure is also in part homogeneous and compact, with clear flow-structure. The inclusions, where present, are always in part fragments of the contact-rocks of the walls of the sills or dykes. Some of the agglomeratic rocks are certainly dykes and not sills, and as such cannot be interbedded tuffs. Every exposure at some place irregularly invades the contact-shales. For these and other reasons their identification as tuffs is dismissed, and it is sought to explain the occurrence of the included fragments by successive injections of the same fissures and the break-up of previously consolidated injected material. _ The geography of the Meldon Aplite is described; it occurs in several dykes, the principal of which extends from east of the western wall of Okehampton Park to the old Ice House on Sourton Tor, a distance of nearly 2 miles. There are other minor dykes north and south of this. 42 Reports & Proceedings—Hdinburgh Geological Society. The texture of the aplite is microgranitic. The principal minerals are albite, orthoclase, microperthite, quartz, lepidolite, green tourmaline, and topaz. Blue apatite is almost entitled to be classed with these. Fluorspar, montmorillonite, and axinite are accessories. Although, in conformity with other observers, the author has described this rock as an aplite, he uses the term with reservations. The rock is neither more acid than the normal granite, nor does it approach freedom from mica, and he submits that the true description, even if cumbrous, would be lepidolite- soda-granite. The whole of the mica is apparently lepidolite, and of 8°70 per cent, the total of the alkalies, ruughly five-eighths are soda and three-eighths potash. Some veins of true granite occur, always of fine grain: in these andalusite is locally developed. It is noted that topaz and andalusite have never yet been found side by side in any Dartmoor granite or granite vein, but topaz may occur in granite which is in contact with slate in which andalusite is present. In one and the same rock the minerals appear to be mutually exclusive, or, in other words, when the conditions are such that topaz may form andalusite is not to be expected. I{.—Enpinsorca Gronoeicat Socrery. October 16,1 1918.—Professor Jehu, President, in the Chair. ‘Peat and its Utilisation.” An Address by H. M. Cadell, B.Sc., F.R.S.E., Vice-President. At times such as these, when the Great War had emphasised the need of conserving all natural and scientific resources, the peat question deserved its full share of attention. The high price and scarcity of coal made the prospect of success in the working of peat greater than it had ever been. During recent years peat had been found valuable for producing many other things besides ordinary fuel. By wet or dry distillation, peat products included alcohol suitable for internal combustion engines, ammonia for agricultural fertilisers, acetic acid and acetone for explosives, paraflin for making wax, creosote for preserving timber, tar for coating roads, oil and spirit for burning and power production, as well as gas and coke for heating and smelting. Besides these more or less complex products, the fibrous red peat of the surface of bogs was of great value for moss litter for bedding horses and cattle, and peat dust was useful for packing fragile objects such as eggs and fruit. Cardboard and brown paper, suitable for packing, had been successfully made in America from peat as asubstitute for wood pulp, and as timber was now becoming scarce much saving might be made by this use of peat, which was one of the most abundant, but least developed, of our natural resources. Immense areas of undeveloped peat moss occurred both in Europe and America, the utilisation of which would not only provide good fuel and other valuable things, but would afford useful employment to a large population in many otherwise poor rural districts. In Europe the peat mosses covered over 200,000 square miles, and in 1 Received November 16, 1918. Reports & Proceedings— Wellington Philosophical Soc. 43 - Canada half a million, while two-thirds of Newfoundland were under peat. Some of the Scottish peat mosses were as much as 50 feet deep and of great age. Others had, like the Flanders Moss in the Vale of Menteith, been formed since the pre-existing forest had been felled by the Romans. ‘The mosses varied greatly in quality as well as in thickness, and all of them in their natural state contained _ between 80 and 90 per cent of water, the elimination of which was ‘generally the rock on which industrial peat-producing enterprises had been wrecked. Vast sums had been lost in trying to dry peat artificially either by pressure or by heat, and an evil spirit like the will-o’-the- wisp seemed to haunt the bogs and lure on the adventurer till he was finally swallowed up. But the light of modern science could show the right path to follow, and as oil shale had only been recognised as one of the precious stones after much loss and hard-bought experience, so would peat moss be made to minister to the needs of man after the wrong roads had been abandoned and the right trail found out. Many new processes have been discovered lately, including Ekenberg’s wet carbonising process of heating the wet peat so that it could be afterwards dried by pressure. The briquettes of dried peat were capable of distillation, and as two-thirds of the mass was volatile and about a quarter fixed carbon, it was clear that once the water was successfully eliminated the peat substance was far more valuable than oil shale. The nitrogen in peat was a very important item, and some mosses contained over 2°5 per cent, and the sulphate of ammonia derived from the nitrogen alone might in good mosses be worth twenty-five shillings per ton of dry peat, which was about five times as much as was yielded by oil shale. Alcohol had been made by the fermentation of peat and its wet distillation, and it was claimed that this product could be manufactured for 3d. or 4d. per gallon. Peat alcohol would be of great value for motors as a substitute for petrol, and if the Government wished to assist the development of this wealth-producing discovery after the War the excise duty might well be greatly reduced, so that the producer would be encouraged to go on and the consumer might obtain the large supply of liquid fuel that was becoming more necessary every day for vehicular traffic and agricultural motor machinery. The development of the peat industry was largely a matter of scientific investigation and technology, and there was in this country an open field and every prospect of final economic success, notwithstanding the failures to achieve it in the past. Ii1.—Geonocgtcan Srecrion oF tHe Wetvtrineron PxiLosopHicaL Society, N.Z. The annual general meeting was held on August 21; 1918. ~The annual report, which was read and adopted, stated that since the preceding annual meeting, September, 1917, five ordinary meetings had been held, at which there had been a number of interesting exhibits and eight papers had been read. ‘The titles and authors of the papers were as follows: (September 19, 1917) “The 44, Correspondence—J, Coggin Brown. Geology of the Papakaio District,” by G. H. Uttley; ‘A Comparison . of the New Zealand and Western North American Cretaceous and Tertiary Formations,” by P. G. Morgan. (October 17, 1917) ‘Natural Regions in New Zealand,” by E. K. Lomas. (May 15, 1918) ‘The Geomorphology of the Coastal District of South- Western Wellington,” by C. A. Cotton. (June 19, 1918) ‘‘ Notes on the Post-Tertiary History of New Zealand,” by J. Henderson. (July 17, 1918) “The Origin of the Amuri Limestone and Flint Beds,” by J. Allan Thomson; “Notes on the Geology of Stephen Island,” by J. Allan Thomson; ‘‘Permo-Carboniferous or Maitai Rocks of the East Coast of the South Island,” by P. G. Morgan. At the meeting a resolution was adopted expressing appreciation. of the paleontological work of the late Mr. Henry Suter; and also a resolution expressing appreciation of the paleontological work of the late Dr. E. A. Newell Arber, in particular of his work on the Mesozoic floras of New Zealand. CORRESPONDENCE. THE GENESIS OF TUNGSTEN ORES. Siz,—It is to be regretted that Mr. R. H. Rastall, when compiling his very useful summary of our present knowledge of the genesis, mode of occurrence, and mineral associations of the ores of tungsten, the first part of which appeared in the Grotoetcan Macazine for May, 1918, had not before him the results of later researches than those of Dr. Bleeck regarding the ore-deposits of the Tavoy district of Lower Burma, as his results have not been accepted entirely by later workers. For the past three years a party of the Geological Survey of India has been working in Tavoy, and the district has also had the advantage of the presence of several enthusiastic private geologists. The Geological Survey party has examined most of the lodes which occur, investigated their contents as carefully as possible, and mapped the boundaries of the granite and the sedimentary series into which it is intruded. Our results may be summarized briefly :— 1. Up to the present time not a single specimen of columbite has been found. 2. Tourmaline does not occur in the ore mineral association, and is not a normal constituent of the granite. The occurrence of tourmaline pegmatites is known, but they are not associated with the ore- bearing zones and do not contain either wolfram or cassiterite. 3. Fluor spar is a widely distributed lode mineral, but it is only found in insignificant quantities. 4. Topaz is known to occur in one alluvial cassiterite deposit, and to-day, after three years of detailed field investigation together with petrological and chemical determinations in the laboratory, has only been found in situ once, in conjunction with fluor spar bordering a lode which contains relatively large quantities of pyrite, molyb- denite, cassiterite, and very little wolfram. There are over one hundred producing mines in Tavoy district alone, and the lodes examined must amount to many hundreds. ; Correspondence—J. Coggin Brown. 45 Wolfram and cassiterite are nearly always associated together, though lodes containing one of these minerals, especially wolfram, to the entire exclusion of the other, are known. The mineral associa- tion in order of deposition is as follows: molybdenite, wolfram, cassiterite, native bismuth, bismuthinite, chalcopyrite, arseropyrite, pyrrhotite, galena, and blende. Scheelite also occurs in small quantities. In Mr. Rastall’s classification of tungsten occurrences into paragenetic sub-types Burma should be associated with Queens- land rather than with Etta Knob and Ivigtut. In a paper read before the fourth Indian Science Congress at Madras in January, 1916, of which only an incomplete summary has been published (see Journ. As. Soc. Bengal, n.s., vol. xiii, No. 2, boron may have been taken by sulphur and arsenic in the pneumato- lytic stages of ore formation here. I am driven to this conclusion by the universal presence of sulphides, generally in the form of pyrite, in the T'ayoyan lodes and the relative absence of minerals containing fluorine and boron. Some of our lodes are pegmatites. They contain felspar as well as quartz. They have the composition, structure, texture, and other characteristic features of normal pegmatites, but they carry wolfram and cassiterite as well. I have suggested that others in which the pegmatitic origin is not so clear may represent a hydrothermal phase of pegmatite development resulting in the production of quartz with the ore minerals. There are cases here where true wolfram and cassiterite-bearing pegmatites pass in short distances along their strike directions into pure quartz veins with wolfram and tinstone. I do not deny the part played by pneumatolytic reactions as they are generally understood. I cannot account for the greisens which sometimes border the walls of lodes in granite and also carry valuable quantities of ore minerais by any other theory, but I doubt whether fluorine and boron played much part in the reactions. It is pleasing to note that Mr. Rastall concludes that there is no real distinction between magmatic segregations and veins in this type of ore-deposit, for if it is correct to regard the pegmatite-aplite group of rocks as differentiation products of granites, it is reasonable to regard their metallic ores as segregations from acid magmas to the same extent. The wolfram occurrences in other parts of Burma are not identical with those of Tavoy, though this district produces by far the greater proportion of Burma’s output. Tourmaline is present in the Mergui lodes and also in those of the Thaton district. Beryl is a common mineral in the lodes of the Yamethin district. Mr. Rastall has alluded to the widely scattered literature on the subject, and to his bibliography on this district the following published papers may be added: ‘‘ Economic Geology of Tavoy,”’ by J. Coggin Brown; ‘‘The Origin of Wolfram and a Preliminary Investigation as to its persistence at depth in the Tavoy District,” by Dr. W. R. Jones. Both these papers are published in a work entitled Lectures delivered at Tavoy under the auspices of the Mining Advisory Board, Superintendent Government Printing, Rangoon, 46 Correspondence— Dr, R. F. Scharff. 1918. ‘‘The Disintegration of Wolfram,” a letter published in the Mining and Scientifie Press, San Francisco, September, 1917, by myself; Zhe Ore Minerals of the Tavoy District, by J. Morrow Campbell, published privately, but available from Messrs. Rowe & Co., Rangoon, As far as I understand their published views, Dr. W. R. Jones supports the pneumatolytic theory of the origin of the deposits, while Mr. J. Morrow Campbell believes that highly siliceous water was the agent which leached tin and tungsten from the magma and at quite moderate temperatures deposited cassiterite, wolfram, and associated minerals in veins. J. Coeein Brown, Assistant Superintendent, Geological Survey of India. Tavoy, BURMA. October 1, 1918. THE FAUNA AND FLORA OF THE GREAT ICE AGE. Sir,—The remains of the past fauna and flora have frequently been utilized in supporting the theory of an Ice Age. But little justice has been done to this subject, although it has been maintained by some authorities that the geological history of both animals and plants furnish strong evidence in favour of an Ice Age. In Sir Henry Howorth’s series of instructive articles in the GxronoeicaL Magazine of August, September, and October last he emphasizes some features in the past and present marine fauna of the Baltic which deserve very careful consideration. His remarks about Yoldia and its distribution apply with equal force to dozens of other species of marine organisms. ‘The argument that because a species now lives at a certain depth in the Arctic Ocean it must have lived at the same depth during the Ice Age much further south is a fallacy, as Sir Henry Howorth points out. Although some forms of animal and plant life readily adapt themselves to changes of temperature in the course of their migrations most of them require for their existence and welfare a uniform temperature. The con- clusions arrived at by Sir Henry Howorth are based on the conditions which obtain almost everywhere near the coasts of Europe at the present day. We may observe Arctic species thriving at considerable depths, while Southern species inhabit the shallow water of the same area. In elucidating the geological history of the Baltic these conciusions, with which I entirely agree, are of the highest importance. R. F. Scwarrr. NATIONAL MUSEUM, DUBLIN. November 23, 1918. OBITUARY. JOHN DUER IRVING. Born AUGUST 18, 1874. DIED JULY 20, 1918. Joun Durr Irvine, the son of Professor R. D. Irving, of the University of Wisconsin, was educated at Columbia University, and Miscellaneous—The Preservation of Meteoric Irons. 47 after taking his degree he joined the United States Geological Survey, carrying out work in Dakota and Colorado in conjunction with Whitman Cross and 8. F. Emmons. His most important Survey work was a memoir on the Leadville district of Colorado. In 1908 he was appointed professor of geology at the University of Wisconsin and afterwards at Lehigh University. In 1907 he became professor of economic geology at the Sheffield Scientific School at Yale. He was also editor of Heonomic Geology from its commencement in 1905 until his death. When the United States declared war he entered the Army, and soon left for France with the rank of captain. At first engaged in railroad work, he subsequently became instructor in a school of mining and engineering as applied to warfare. Hard work and unremitting attention, to duty wore him out, and he succumbed to pneumonia following influenza, to the deep and lasting regret of all who knew him, both in the Army and in the scientific world. MISCHLUANBHOUS. OTD On rae Discovery oF A MrrHoD OF ARRESTING THE DECOMPOSITION OF Merroric Irons, sPPLIED SUCCESSFULLY To MurrrorITES 1N THE British Musrum (Narorat Hisrory). Henry Gadsdon (1861-1918), who died on December 2, aged 57 years, had been for over ten years employed at the Natural History Museum as french-polisher.. He was an excellent workman of the best type, one who took pride in maintaining the high quality of his work. It is thanks to his aid that the problem of safeguarding the Meteoric Irons in the National Collections has—so it is hoped—been successfully solved. Kvery curator who has had such specimens under his care knows well the difficulty of preventing them from rusting. ‘The chief agent in causing the mischief appears to be the unstable protochloride of iron— lawrencite—which immediately breaks down in the presence of damp. This substance is disseminated through certain specimens in extremely thin veins, and, since the change that takes place causes it to swell, such specimens are often found to be split across; further, as a result of the alteration of the lawrencite the nickel-iron alloy which is the principal constituent of the meteorite is attacked, and finally nothing is left of the specimen but a lump of rusty fragments and powder. By keeping the air in the case as dry as possible, the rate of attack may be slackened, but only slackened; the ultimate end is just as sure and inevitable. Varnishing the specimen is more effective, but this process completely spoils the specimen for exhibition purposes. Six years ago, in 1912, as the result of experiments made on pieces of steel exposed to the weather, it was thought that coating the meteorites with a thin, transparent film of shellac by the process of french-polishing might overcome the difficulty without sensibly interfering with the appearance of the specimens, and the Keeper of Minerals decided to have first those specimens which showed considerable signs of rusting treated in this 48 Miscellaneous—Mr, F. W. Harmer, M.A. manner. The work was entrusted to Gadsdon. At first he experienced some difficulty in getting the polish to work properly on the metal, but soon discovered the proper temperature to give satisfactory results, and proved very successful and skilful in treating the specimens. It calls for a careful inspection at a glancing angle to realize that there is anything on a specimen which has been polished, and the harmful rusting has been all but stayed. It is true that some specimens have of necessity been treated more than once, but the cause is no doubt the action that has still gone on in the depths of the cracks within the specimen, and there is evidence that the action is steadily becoming feebler. In one of his books Wells suggests that in the course of a century or two Meteoric Irons will be represented in museums by lumps of rust; at the Natural History Museum at least, thanks to the method | first applied by Gadsdon, it may be that the Meteoric Irons will retain their original form and constitution much longer than that eminent writer foreboded. Honorary M.A. conrerrep By CAMBRIDGE UNIVERSITY ON Mr. F. W. Harmer, F.G.S. At a Congregation in the Senate House at Cambridge on Dec. 7 the Public Orator, Sir J. E. Sandys, delivered the following speech in presenting Mr. Frederic William Harmer, F.G.S., for the titular Degree of Master of Arts honorts causa :— ‘< Abhine annos quattuor et octoginta natus, adest vir in geologiae scientia penitus exploranda per vitae partem longe maiorem feliciter occupatus, qui patriae toti devotissimus, Angliae Orientalis regionem nobis propinquam @ ante omnia praetulisse confitetur. Vitae in parte prima, aevi tertii geologici reliquiis diligenter investigandis operam dedit; in secunda, comitatus Norfolcensis in urbe maxima honore municipali summo praeclare functus est; in tertia, ad aevi tertil geologiam, ad amorem suum primum, animi ardore prope iuvenili reversus est. Idem (ne plura commemorem) glacialis aevi et causas primas et eventus ultimos perscrutatus est; ventorum vim in caeli temperie mutanda antiquitus non minus quam recenter multum valuisse luculenter ostendit :. ipsas denique causas sollerter investi- _ gavit, quae loca illa nobis propinqua, paludosa illa quidem et uliginosa, sed pulchritudine sibi propria exornata, aut olim crearunt aut in amplitudinem maiorem auxerunt. ‘‘ Habetis, Academici, exemplar viri, non modo et suo et uxoris suae solo natali, sed etiam patriae toti in unum coniunctae, et rerum naturae studiis devotissimi. Nostis Tulliana illa de loco suo natali verba: ‘Omnibus municipibus duas esse censeo patrias, unam - naturae, alteram civitatis ... 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OriGinaL ARTICLES. Page REVIEWS (continued). Paleolithic Flint Inplements from | M. . Wilson: Timiskaming Co., High Level Verraces of Thames Quebec, Canada Valley. By HENRY DEWEY, | W. A. Johnston : F.G.S., of H.M. Geological Ontario Survey. (Plate II.) ¢ Canada, Department of Mines, Climate and Time. By hk. M. Ottawa DEELEY, V.P.G.S i South Australia, Department of Quartzose Conglomerate at Caldon Mines, Adelaide 86 Low, Staffs. By J. WiILFrm Permian Insects, Sydney, New JACKSON, F.G.S., and W. Wi. South Wales 87 ALKINS, B.Se. f J. Allan Whomson : Notes on Ammonites. By LL. I. | Considerations SparH. B.Se., F.G.S. Ree Noteson Yunnan Cystidea. PartIII. UI]. Reports and PROCEEDINGS. By F. A. BATHER, D.Sc., F.R.S. The Royal Society The Carboniferous Limestone of | Geological Society of london-— the Wrekin. By lL. M. Parsons, December 4, 1918 M.Se., F.G.S. (With a Sketel- December 18 VW. Tevinws IV. CORRESPONDENCE. Dr. G. Hickling : Genloen of Man- | Dr. F. R. 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PALAOLITHIG FLAKE IMPLEMENTS, HIGH-LEVEL TERRACES OF THE THAMES VALLEY. THE aaeeney GHOLOGICA L MAGS NE” ' NEW SERIES. DECADE VI. Y@L.-Vh No. II.— FEBRUARY, 1919.\ M, on; o A a /Ona| Wit Wser _ QOrREGTaN A L. A Cae Baek! nee T.—On some PatmonirHic FLaAkre-IMPLEMENTS FROM THE HigH LrvEL TERRACES OF THE ‘’HAMES VALLEY. By Henry Dewey, F.G.S., of H.M. Geological Survey. (PLATE II.) VER most of North-Western Europe the occurrence of river- terrace deposits containing Paleolithic implements has been -long known, and the establishment of a sequence of forms among these implements has resulted from the researches of Gongmenetn and especially of French archeologists. With the pioneer work the name of M. Boucher de Perthes,! of Amiens, will always be associated. His was the task of convincing unwilling minds of the human work- manship of the ancient flint- weapons found in the eravel-pits of the Somme Valley. For the next great advance we owe a debt of gratitude to ‘another French savant, the late Professor Victor Gommont, 2 for his life-work was the taking up of the researches of his predecessor and establishing the sequence of cultural types and their relative chronology.?* Flint implements of the same forms had long been known to occur in the gravels of the Thames Valley; but as their precise stratigraphical position had never been ascertained, it was held generally that the several forms occurred on one and the same horizon. This assumption, based on careless collecting, became a strong prejudice in the minds of some archeologists, but no efforts were made to test by proper investigations the truth of the hypothesis they held. In view of the conclusions arrived at by the Continental authorities, however, it was certainly desirable to examine at home the validity of the stages of paleolithic culture they had found to hold good abroad. Some investigations were therefore undertaken in the years 1912, 1913, and 1914, by the Geological Survey and the British Museum, in co-operation, at ! De Vindustrie antiquitées Celtiques et Antédiluviennes, Paris, 1847. 2 L’ Anthropologie, xix, pp. 527-72, 1908; Compte rendu de I’ Association Francaise, 1908, pp. 634-45 ; Assoc. Préhist. Congrés de Lille, 1909, p. 437 ; Revue préhistorique, 1909, No. 10; Bull. Arch., 1911, p. 27; Congrés inter- national d’ A> thropologie, xiv, p. 240, 1912. 3. The names of Prestwich and Lyell, and later those of Messrs. Spurrell, W. Smith, Kennard, Leach, and Chandler, should, however, be mentioned in connexion with the advance in scientific classification of the Paleolithic periods. 4 These stages are in descending order: Azilian, Magdalenian, Solutrean, Aurignacian, Moustierian, Acheulian, Chellean, Strépyan. DECADE VI.—VOL. VI.—NO. II. 4 50 Henry Dewey—Palwolithic Flake-implements various sites in North Kent and near Rickmansworth. The results are published in Archeologia,’ but a brief account of these results is necessary for the discussion of the present paper. All the flake- implements illustrated * in Plate II, and described on pp. 538-5, were collected by the author, or in his presence, at these sites during visits made to the pits after the publication of the official work. The chief interest attaching to these flake-implements is the light they throw upon the ancestry of the types that became dominant in the cave periods and in the Neolithic age. During the early paleolithic periods core-implements were characteristic and pre- dominant; in the early cave period (Le Moustier) flake-implements suddenly, and almost completely, replaced them; but that the pattern was not unfamiliar to the earlier peoples is proved by the occurrence of similar types, and it may therefore be concluded, either that the earlier men were not in such urgent need of these forms, or that they preferred the use of others. The age of these flake-implements is indicated by the position in which they were found. ‘Deposits oF THE 100 Fr. TERRACE OF THE THAMES. The first site selected for investigation was the large gravel-pit, at Milton Street, near Swanscombe, known to the owners (The Associated Portland Cement Manufacturers) as the Barnfield Pit. The Company, through one of their Managers, Mr. George Butchard, courteously invited the British Museum and the Geological Survey to undertake an examination of the sand and eravel for flint implements before this overburden was removed, preparatory to the quarrying of the underlying chalk for making cement. A preliminary visit showed that over the whole area around the pit there was a persistent series of Pleistocene deposits composing a 35 ft. section. As the deposits had already been removed to various depths at different parts of the pit it was possible to examine nearly every bed without shifting those above, and the danger of mixing the beds was thereby avoided. The following sequence was found to occur :— Soil. Feet. Gravel, irregular pockets and pipes in stiff clay (the Upper Gravel) \ 4h Loam (the Upper Loam) fh 2 Gravel and current-bedded sand (the Middle Gravel) . ; . 8 Loam and Marl (the Lower Loam) : : : : . 2-4 Gravel (the Lower Gravel) . 5 ! : ! ‘ : . 5-6 On the northérn side of the pit the gravel overlaps the Thanet Sand and hes directly on the Chalk. The overlap is due to the general southerly dip. About two weeks’ digging resulted in the collection, and accurate location, of many paleolithic implements and rough flakes, and 1'Vol. Ixiv, pp. 177-204, 1913; vol. lxv, pp. 187-212, 1914; vol. Ixvi, PP. 195-224, 1915. 2 iBone these drawings and descriptions I am indebted to my een Mr. Reginald A. Smith, of the British Museum. from High Level Terraces of Thames Valley. 51 sufficed to prove that there was a sequence of paleolithic types corresponding to a succession of Pleistocene deposits. The beds of the lower gravel contained many large flakes without secondary working, and a few cylindrical nodules either chipped into a chisel edge or roughly pointed at one end. ‘These resemble some of the implements discovered by Dr. A. Rutot from a locality known as Strepy, in Belgium. No true palzolithic implements, however, were found in this gravel. The Mippre Graver contained a large number of true implements, those found near the base being of rougher workmanship than the smaller number lying at the higher levels. From the lower part nearly all were of ‘‘ pear” shape, many carefully worked and devoid of cortex, while others were rougher, with much cortex remaining at the butt end. There was also a large number of chips and flakes without signs of trimming or usage, many closely resembling, except in size, the flakes from the Lower Gravel. Only four worked scrapers were afterwards found at this horizon, two round scrapers and two pointed forms (see Pl. II, Figs. 1, 3,5, 6). None of the implements shows the slightest mark of abrasion, a fact which seems to indicate that they had not travelled far, but had rather been dropped into the river somewhere in the heighbourhood during the time the gravel was collecting. ‘They are strictly contemporaneous, therefore, with the gravel and not derived from an older source. Moreover, as no forms characteristic of higher levels occurred with them the gravel in question may be assigned to one period, In the Upper Gravel no implements were found, but the workmen stated that implements of ovate form and white patination had been found in the clay of this gravel-bed. On the eastern side of'a road (Craylands Lane) bounding the Barnfield Pit, a small gravel-working had been opened. This deposit, which lies at a slightly higher level than most of the Middle Gravel, is current-bedded and overlain by even-bedded gravel with clots of clay and ae filling channels in its surface. At the top of the current-bedded gravel some sixteen implements have been found. They are all ovates, most with the edge curved like a reversed § and patinated white. In other words, they are typical St. Acheul forms, and being practically unrolled must be contemporaneous with the gravel in which they were discovered. All these deposits lie on a widespread terrace-platform cut by the Thames in the Chalk and Thanet Sand. The base of the Pleistocene beds is about 90 feet above the Ordnance Survey datum, and the deposits are described as those of the 100 ft. terrace of the Thames. 'o summarize the evidence derived from these stone implements for a complete ‘‘ Drift”? sequence in the deposits of this terrace it has been seen that the lowest gravel contains no true paleolithic form, In the Middle Gravel all the forma may be assigned to the Chelles type of the Somme Valley, and DEOL to those of pine lower series at St. Acheul. The small collection of ovate forms from the pit east of Chaytande Lane can be assigned provisionally to the St, Acheul type, as they are all of ovate form; several have a characteristic pronounced twist 52 Henry Dewey—Paleolithie Flake-umplements in the usual direction, and many have ine white or cream patination so frequently found at St. Acheul. In another pit (Globe Pit) near Greenhithe a flake- implement having a china- white patination was found in loam from which forms assigned to the Le Moustier period have frequently been collected. A racloir flake belonging to the St. Acheul period was dug out of the clay of the Middle Gravel. Subsequently to the deposition of the 100 ft. gravels a tributary of the Thames, the Ebbsfleet, cut out a valley some 50 feet deep. This valley was afterwards partially filled up with an unstratified mass of chalky rubble, sand, pebbles, and clay containing a number of bones, teeth, and tusks of various extinct mammals. At the base of this rubble, and lying on a fairly even floor, many thousands of flakes, cores, and implements have been found. ‘The cores resemble the carapace of a tortoise, and the worked flints are characterized by a peculiar faceting of the platform or striking-plane. The core was carefully flaked and a complete implement struck off at a single blow on one of the facets, but the underside carried an enormous bulb of percussion. . Precisely similar forms were discovered by Professor Commont, who succeeded in dating the finds as belonging to the early part of the Le Moustier period. In the Ebbsfleet Valley the flake industry had very nearly replaced the core implement, as has already been described by Mr. Reginald A. Smith.? The investigations at Mill End, near Rickmansworth, were less decisive in their results. They were undertaken in the large gravel- pit where some 16 feet of red gravel with seams of sand are exposed. A peculiar feature of the gravel is the occurrence of large cave-like spaces, which may have been formed by the thawing of frozen masses of sand. ‘I'hese deposits rest upon a wide terrace flanking the River Colne. Paleoliths of Chelles type have been found in abundance in the past; in fact, nearly every implement that has come from this pit is of the early Chelles coup-de-poing form, with heavy base and acute point. ‘The Croxley Green pit, higher up the river, on the other hand, has yielded numbers of the early St. Acheul, ovate, type of implement.? Asa result of the joint examinations by the Geological Survey and the British Museum, but very few implements were found, although such as were discovered supplied confirmatory evidence of Sir Hugh Beevor’s conclusions. One good flake-implement resembling a coup-de-poing, but probably a racloir, was secured by the author: it is figured in Pl. II, Fig. 7, and may be compared with one found by the late Lieut. C. H. Cunnington at Knowle Pit, Savernake. The two implements are very nearly identical as regards workmanship, shape, size, and use. These British deposits and their contained implements may now be compared with those examined by Professor Commont in France. He worked out in detail the paleolithic sequence in the Pleistocene deposits of the terraces in the valley of the Somme. There are there four terraces representing the succession of levels at 1 Archeologia, \xii, 532. * Sir Hugh Beevor, Proc. Geol. Assoc., xxi, 245. from High Level Terraces of Thames Valley. 53 which the river has undercut its banks since the Pliocene period. The deposits of the highest terrace are Pliocene, and no flint implements have been found in them. ‘The second terrace deposits are early Pleistocene and contain Strépyan forms; the third, or 30 metres, terrace gravels have Strépyan forms at their base, and in the sands near the top implements assignable to early Chelles. Upper Chelles types are plentiful in the gravels of the lowest terrace. Sweeping downward from the plateau over these terraces are two mantles of loam, an earlier and a later, called respectively the older and the younger Loess. Each of these Loess deposits is separable into upper, middle, and lower beds—those of the younger Loess being called locally the Ergeron; each seam is underlain by a bed of pebbles, while the surface of each is an ancient soil. Caleareous concretions, known as Poupeés or Loess-ptippchen, occur at the base of both Upper and Lower Loess, those of the latter being larger than the piippchen of the Upper Loess. The ancient Loess consists in upward succession of (a) the damon rouge sableux, (b) the limon ad points noirs, and (¢) the limon rouge. In gravels at the base of the dimon rouge sableux the whole series of forms assigned to the St. Acheul stages are found, but no implements of any kind have so far been found in beds 6 and e. In the younger Loess, and especially in the pebble-beds at the base, the Le Moustier types have been recorded; some occurrences of implements of the later cave periods also occur in this younger Loess. Most of the Chelles implements are coups-de-poing. This fact is so striking that it led M. de Mortillet? to conclude that no other type of implement was made during that period, but more recent finds show that in the Somme Valley as in that of the Thames flake- implements also occur, though rarely, with the other forms. One of these? is practically identical in every detail with that figured on Pl. II, Fig. 2, and further corroborates the inference drawn from the English evidence. ‘These curved scrapers possess the characteristics of the racloirs of Aurignacian age found at Chatelperron and to some extent the broad points from the Abri Audi. They are of clumsier technique, and are larger, but evidently designed to meet a similar need. In the following notes a brief description is given of the implements figured upon Plate II.* _ Fic. 1.—Large flake of yellow-mottled flint, unrolled, with broad rounded end flaked to form a scraper, the under (flat) face trimmed at end; bulb of percussion and flat striking platform or butt. A median ridge runs half-way from the rounded end, and the side edges are irregularly worked. Length 4-1in., breadth 3-1lin., thickness 1-1in. From the lower part of the Middle Gravel at Barnfield Pit, Swanscombe, Kent, for which see Arche@ologia, \xiv, 185. A specimen pairing with this is in the British Museum. It came from the Somme Valley drift at St. Acheul, and has the following dimensions: 1 Bull. Soc. d’Anthr., Paris, 1887, ser. 111, pt. x, p. 173. 2 VV. Commont, L’ Anthropologie, xix, p. 551, fig. 40, 1908. * [The Editor regrets that the name of the author has, by an accident, been inserted at the foot of Plate II instead of that of his friend, Mr. R. A. Smith, who kindly made the drawings for him.—ED. ] 54 Henry Dewey—Paleolithic Flake-vmplements length 3-7in., breadth 3-lin., thickness 1-lin. An inadequate drawing is included in Lartet & Christy's Reliquie Aquitanice, p. 14, fig. 7. Though rather darker in colour, the character and workmanship are identical, and the form must therefore be recognized, not as an accident, but as a type, though round scrapers or planes are seldom met with in the river gravels. Obermaier reproduces one 3-7in. long from St. Acheul (Rue de Boves) and classifies it as a grattoir (Die Steingerdte des franzisischen Altpaldolithikums, fig. 84) dating not from the earliest but the best Chelles period, when hand-axes were the dominant form. Fic. 2.—Massive yellowish-grey flake, Tieton and unrolled, with a straight edge on left used as a side-scraper, and on the right towards the top a thick curved edge, worked as a finger rest; bulb of percussion and flat platform at base. Length 3-3 in., breadth 2-3 in. From the pit east of Craylands Lane, Swanscombe. : This is a rare form, and might be mistaken for a knife, but the plain underface on the left shows it was used as a racloir. The mode of holding such an implement (called a knife) was illustrated by the late Professor Commont in L’ Anthropologie, xix, p. 551, fig. 40, 1908, reproduced by Obermaier, op. cit., fig. 67a; a side-scraper with similar accommodation for the finger is represented in his fig. 99. A few bold striations on the bulbar face of this specimen should not be overlooked. Fic. 3.—Round scraper on a broad gabled flake, with a spur at one end of the planing edge; of typical “‘ mahogany’’ flint as common at Swanscombe, with bulb of percussion, large flat platform, and plain flat bulbar face. The side edges are parallel, as in the later blade-scrapers, but the specimen is rather broad for that category. Length 2-7in., breadth 1-9in., thickness 0-9in. A rare form from the Drift, but two specimens somewhat larger were found in the same Barnfield Pit, Swanscombe (now in British Museum), one having a spur in the same position; and a more slender example, from the lower part of the Middle Gravel there, is recorded in Archeéologia, |xiv, 187 (cf. Obermaier, op. cit., fig. 85, from Rue de Boves, St. Acheul). Fic. 4.—Yellow-brown ridged flake, with bulb and flat platform at one end and at the other a sloping worked edge ending in a point at the top and extending round a shoulder down the left side. The longer edge on the right also has signs of use, and the plain bulbar face has a number of scratches nearly all parallel with the longitudinal axis. The principal features are the top angle and the steeper shoulder on the left; no doubt used for scraping. - Length 8:2in., breadth 2-lin. Found in gravel at Milton Street, Swans- — combe, Kent. Fic. 5.—Black and yellow mottled flake, ridged and slightly notched on either side of the thinner end to form anose; the broader end rounded and underface quite plain, the bulb missing. The working end of an implement is often emphasized by one or two side notches, but the ‘present specimen cannot be classed as a borer. Jength 3-2 in. , breadth 1-7in. From gravel at Milton Street, Swanscombe, Rom Similar ‘specimens from St. Acheul are figured by Obermaier (op. cit., figs. 56, 78) and assigned to the Chelles period. Fie. 6.—Broad olive-brown flake, with careful shallow working along the right edge, where secondary work indicates use as a side-scraper (racloir). The edge near the point on the left is zigzag and bruised, and the lower edge is thick and rough, the bulb remaining in the lower angle on theright. The bulbar face.is not flat, and the edge is chipped in places. Length 4in., breadth 3in. From gravel.at Milton Street, Swanscombe, Kent. The flaking of this specimen, apart from the result of use, seems to be rather in the style of St. Acheul than of Le Moustier, though in form the resemblance to the latter. type is very striking. Compare specimens from St. Acheul figured by Commont, Les Hommes contemporains du Renne, figs. 45, 51. Fic. 7.—Triancular hand-axe, lustrous brown, made from a flake, with bulb at angle of base ; the side edges nearly straight and the lower edge thick and crusted; worked on both faces along the edges, and the point carefully formed. Length 2-Sin., breadth 1-9in. From Mill End Pit, near Rickmans- worth. (See Archeologia, |xvi, p. 196.) from High Level Terraces of Thames Valley. 55 Fic. 8.—Small subtriangular implement, made of an olive-green flake, with erust at the butt and traces of an older ochreous surface on the front. The bulb is at one angle of the base, and the other is the lower limit of the work on the right-hand edge, which must be classified as a side-scraper, as the bulbar face is untouched. Length 2-8in., breadth 2in. From Knowle Farm Quarry, Savernake Forest, Wilts. The horizon is unknown, but the specimen has all the appearance of a racloir or side-scraper of Le Moustier date. (See Archco- logia, xvii, p. 30, fig. 2.) Examination of any representative collection of flint implements shows that there are assemblages of forms each fashioned after an accepted pattern. Of the paleolithic implements, those belonging to the Drift. period are chiefly of a general pear-shape in outline among the earlier deposits, but ovate in the later, but both are flat although made from trimmed cores; that is, they are chipped on two faces, and not simply spindle-shaped pieces with sharp points, but flattened cones and discs with cutting edges. With the advent of the Cave periods the core was given up and the flake adopted. Nearly all *‘cave’”’ implements are made from flakes; some are carefully worked on a disc-face, a facetted platform prepared, and by a single blow on this platform a complete implement detached from the core. By this means half the work expended on their manufacture was saved and the implements were as effective as the earlier core-forms. Many flakes were used as “scrapers’’; some being trimmed along one side to make a comfortable hold which would not cut the hand. Asa result of use the scraping edge gradually got chipped off so as to meet the holding-edge, and a triangular form resulted resembling in outline the coups-de-poing. Such are figured on Plate II. The original implement was a racloir; by use it became a coup- de-poing, but it is doubtful if they were ever used as points. . In the later Cave periods the principal tools were the racloir or side-scraper, the grattoir or plane, and the burin or graver. Among the implements described on pp. 53-5 examples of the racloir and erattoir are noted. The age of the implements is determined by their stratigraphical position; they are either Chelles or St. Acheul.’ They were therefore evidently used by early paleolithic man, and that they were in use over widespread areas is proved by their occurrence alike in England, France, and Belgium. What is perhaps of even more interest is the variety of form of the tools, pointing to the differentiation of function and of speciali- zation among the workers. Thus the coups-de-poing, the grattoirs and the racloirs, three kinds of tools, of which each attains its maximum development both as to numbers and style of workmanship at a different period, are all known in the Chelles stage. ‘The early paleolithic forms may therefore be regarded as the ancestral types of the later periods. During the paleolithic periods some tools and weapons decreased in numbers, while others greatly increased. Attending this alteration of dominant form was the gradual evolution from one type to another, and there is no more interesting instance of descent with modification than that of the Neolithic celt from the paleolithic coup-de-poing. ‘his subject has already been dealt with by Mr. Reginald Smith,’ and it suffices here to say that in any Archeologia, vol. Ixvii, pp. 27-48, 1916. 56 Henry Dewey—Paleolithic Flake-vmplements. representative collection similar instances could be found. It is to be hoped that the histories of the modification of other characteristic forms may be traced. They are suggested by such forms as are figured on Plate II, and especially the racloirs and grattoirs, and there can be but little doubt that intermediate forms exist. These modifications of the implements imply changes in the needs of the men who used them; changes brought about presumably by different climatic conditions, the incoming of cther animals and plants, and the substitution of co-operation for hostile competition. The decrease in the relative proportion of weapons to tools accompanies the increase of civilization and marks the advent of the artistic races. Co-operation among men was soon followed by that larger co-operation between man and the animals, when the hunter became the herdsman and shepherd ; the resulting domestication was perhaps reciprocal. But it must always be remembered that the histories of the several types of implement could never have been traced without the aid of geology. For certainty as to relative chronology was unattainable until the precise location of the finds was ascertained. Before the necessity of such precision was realized no better classification could be made than that of ‘the late Lord Avebury,' who divided all flint implements into paleeolithic and neolithic.? All that were not of the one age belonged to the other, and all members of each group were considered to be more or less contemporaneous. Geological observations, however, proved the error of such generalizations, and supplied the means of fixing the relative ages of the finds’ Flint implements then promised to become of value to geologists as ‘‘ zone”’ fossils, and although uncertainty still exists obscurities are being cleared up. ConcLUSIONS. The early paleolithic implements of France and Belgium have been classified according to their form into two groups, namely, the coup- de-poing or pear-shaped; and the limande, or ovate, forms. Where these implements occur in river-deposits, e.g. in the Somme Valley, the beds containing the ‘‘coups-de-poing” always underlie those with the ‘ limandes ” The ‘‘coups-de-poing”’ are therefore assigned to an earlier or Chelles period and the ‘‘limandes”’ to a later or St. Acheul period. Later than these implementiferous deposits there are others of a different character in which le flake-implements known as Le Vallois flakes; or, from their resemblance to the implements found in eaves at Le Moustier, as Mousterian. So far as scientific research has been carried in England a similar sequence has been found. The dominant types of implements in the. Chelles and the St. Acheul periods were made from cores, whereas the Mousterian ushered in a great abundance of flake-implements, among which coups-de-poing and limandes are rare. ‘ But see Lyell, Antiquity of Man, 4th ed., 1873, ch. vili-x. 2 Lubbock, Prehistoric Times, 1869. R. M. Deeley—Climate and Time. 57 During the later Cave periods the flake-implements show more skilled workmanship and a greater variety of forms, and this improvement is maintained in the Neolithic age. The occurrence, however, in the Chelles and St. Acheul periods of most of the types of flake-implements, such as the grattoir, the racloir, and the knife, points to the fact that early paleolithic man was already acquainted with the patterns and methods of making the flake-implements, but for unknown reasons he preferred, or was compelled to use, the core-implement. Evolution or descent with modification can be traced from some paleolithic to neolithic types, corresponding with changes of conditions and a gradual advance in civilization. Without the aid of geology no precise chronology among cultural stages could be traced; with its aid, time-relationships can be determined and the several types of flint-implements, instead of of being mere objets de vertu, acquire a new value as ‘‘ zone-fossils’”’. Il.—CrimatEe ann Tre. By R. M. DEELEY, V.P.G.S. IR CHARLES LYELL in his Principles of Geology, published in 1834, remarks upon the accumulating proofs that the climate of the earth had undergone great changes in the past, and he endeavoured to show that these changes might have been produced by the varying distribution of sea and land. He says, ‘‘ But if, instead of vague conjectures as to what might have been the state of the planet at the era of its creation, we fix our thoughts steadily on the connexion at present between climate and the distribution of land and sea; and if we then consider what influence former fluctuations in the physical geography of the earth must have had on superficial temperature, we may perhaps approximate to a true theory.” The attitude adopted by Lyell may be well illustrated by a few quotations from chapter vii of the above-mentioned work :— ‘““The ocean has a tendency to preserve everywhere a mean temperature, which it communicates to the contiguous land, so that it tempers the climate, moderating alike an excess of heat or cold. The elevated land, on the other hand, rising to the colder regions of the atmosphere, becomes a great reservoir of ice and snow, attracts, condenses, and congeals vapour, and communicates its cold to the adjoining country.” ‘‘Among other influential causes, both of . remarkable diversity in the mean annual heat, and of unequal division of heat in the different seasons, are the direction of currents and the accumulation of drifting ice in high latitudes.” ‘If we now proceed to consider the circumstances required for a general change of temperature, it will appear, from the facts and principles already laid down, that whenever a greater extent of high Jand is collected in the polar regions, the cold will augment; and the same result will be produced when there shall be more sea between or near the tropics; while on the contrary, so often as the above conditions are reversed, the heat will be greater. If this be admitted, it will follow as a corollary, that unless the superficial inequalities of the 58 R. M. Deeley—Climate and Time. earth be fixed and permanent, there must be never-ending fluctuations in the mean temperature of every zone; and the climate of one area can no more be a type of every other, than is one of our four seasons of all the rest.” Lyell goes on to describe the ‘“ position of land and sea which might produce the most extreme of cold of which the earth’s surface is susceptible’’, and concludes that if the continents were grouped about the equator the extreme of heat would be experienced, whereas if they were grouped about the poles the extreme of cold would be attained. There is nothing in Lyell’s writings to lead us to suppose that he thought that the continents were ever grouped in this way. He assumes such an arrangement as an extreme case to show that his theory will hold.even then; and he clearly recognizes the fact that even comparatively small changes in the distribution of the land would considerably affect the climate. James Geikie,’ discussing Lyell’s theory, says, ‘‘But we are assured that no such distribution of land and water as Lyell thought necessary for the production of our Glacial Period ever obtained in Pleistocene times. We have no reason to doubt that the positions of land and sea were practically the same as they are now.’ But the view is now gaining ground that the changes in the distribution of land and sea which are known to have occurred in Pleistocene times were sufficient to affect the temperature appreciably. Croll? also dissented from Lyell’s theory. He says, ‘‘The only — other theory on the subject worthy of notice is that of Sir Charles Lyell. These extraordinary changes of climate are, according to his theory, attributed to differences in the distribution of land and water . . . It will be shown in subsequent chapters that this theory does not duly take into account the prodigious influence exerted on climate by means of the heat conveyed from equatorial to temperate and polar regions by means of ocean currents.” Lyell did not go to the lengths Croll did on this subject; but that he was quite well aware of it and considered it the following remarks of Lyell show: ‘‘ The general climate of Europe is materially affected by the volume of warmer water thus borne northwards; for it maintains an open sea free from ice in the meridian of East Greenland and Spitzbergen.” — Mr. C. HE. P. Brooks * has recently devised an empirical method of calculating the probable alteration in the temperature that might be expected from known geographical changes in the outline of the continent of Europe during late geological times, .and he considers that they were sufficiently great to cause the Glacial Period. . However, he recognizes that such changes could not account for the four great cold periods of the Pleistocene we are now coming to recognize. He suggests that the weight of the ice slowly weighed down the land until the new geographical conditions thus introduced caused the ice to disappear and the climate to ameliorate. On the _1 The Great Ice Age, 3rd ed., p. 792. 2 Climate and Time, p. 8. j * Quart. Journ. Roy. Met. Soe., vol. xliii, pp. 159-73, and vol. xliv, pp. 253-70. J. W. Jackson & W. H, Alhins—Quartzose Conglomerate. 59 disappearance of the ice the land again slowly rose, reintroducing glacial conditions. ‘This is supposed to have taken place four times in succession, each succeeding cold period being less severe than the last. In Europe there may appear to be some evidence in favour of the view that the periods became less cold as they succeeded each other; but in America there is little evidence of this kind. In Europe during the first cold period the Straits of Dover probably did not exist and the ice advanced over the area now occupied by the North Sea. The opening of the straits at alater period much restricted the advance of subsequent ice-sheets. I have suggested that the Glacial Period was the result of two agencies acting together. Separately they could not produce the required conditions ; but jointly they could. It is well known that the great polar cyclones of the earth are acting in direct opposition to the gradient of temperature on the earth’s surface, and produce the poleward flow of the air in temperate regions.! The energy which keeps these cyclones in action is very probably cosmical and may undergo periodic fluctuations. In pre-Tertiary times the distribution of land was seldom such as to lower the temperature sufficiently to enable a temporary decrease in the strength of the polar cyclones to produce a glacial period. In Pleistocene times, however, the polar areas became so continental or landlocked that the periodic waning and strengthening of the polar cyclones led to alternating cold and warm periods. Winds from the Poles towards the Equator do blow, of course, but they are not anticyclonic. They are merely surface winds, or winds resulting from travelling cyclones. The great cyclonic low-pressure areas of the Poles persist throughout the year. Il1.—Own rue Discovery or a Quarrzose ConGLoMEMRratEe At: CALDON Low, StTAFEs. By J. Winrrip JAcKson, F.G.§., and W. E. ALKINS, B.Sc. URING a visit to the limestone quarries at Caldon Low last September we had the good fortune to discover an interesting exposure of a quartzose conglomerate containing numerous fossils. The bed was exposed in a strong joint-face running approximately N.N.W. to 8.8.E., at the northern extension of the quarry on the north-west flank of the Low, just beyond the mineral line of the North Staffordshire Railway. ‘he altitude is about 900 feet O.D. The conglomerate apparently extended some little distance to the south-west before the opening of the quarry, as we ascertained that some 20 or 30 yards had been removed in gaining access to the limestone behind. It appears to extend for some distance round the flank of the Low towards the north-east. _ In the section exposed the conglomerate did not appear to possess definite bedding in its lower portion ; but higher up the slope of the hill, on the 8.8.H. side of the section, it was seen to pass upwards 1 Phil. Mag., vol. xxx, pp. 13-33, July, 1915; vol. xxxi, p. 399, April, 1916 ; vol. xxxv, pp. 221-36, March, 1918. 60 J. W. Jackson & W. HE. Alkins—Quartzose Conglomerate into thinly-bedded impure limestones with arenaceous layers and lenticular beds of quartz-pebbles, dipping N.N.W. at an ‘angle of 30°. Strong joints, at right-angles to these inclined beds, Gaended downwards into the more Gansete conglomerate. The condition of the section rendered the relation of the conglomerate and upper inclined beds to the massive light-grey limestones (Productus humerosus-beds) of Caldon Low somewhat. doubtful. On the 8.S.E side the conglomerate and inclined beds appeared to overstep the truncated ends of the Huwmerosus-beds (which exhibited little or no dip), thus suggesting an unconformity or a fault. At the opposite end of the section some inclined grey limestones, in part crinoidal, had been left as a low ridge running approximately W.S.W. to E.N.E., i.e at right-angles to the con- glomerate section. These beds formed a small anticline near the conglomerate, and may dip under it to the E.N.E.; but this is not certain. The relationship of these beds to the Humerosus-beds could not be ascertained owing to the intervention of the quarry-platform. Judging from the specimens obtained the conglomerate appears to consist mainly of water-worn pebbles of vein-yuartz and quartzite, about the size of hazel-nuts: many of these are green-coated. Mixed with them are small pebbles of red jasper, black limestone, chert, light-buff micaceous sandstone, purple voleanic ashes and tuffs, etc., together with water-worn fragments of grey compact limestone, sometimes of large size, the whole being cemented together by a calcareous matrix. Numerous fossils, chiefly Brachiopods, were obtained from the blocks of conglomerate lying in the quarry. The matrix in and around these has a structure resembling oatmeal. Pebbles of limestone, vein-quartz, fine grey oolite, and other rocks, are also present. The peculiar ‘‘ oatmeal” type of matrix is particularly — striking, and in section the structure is not unlike that of the penecontemporaneously brecciated limestones figured by Professor S. H. Reynolds and Dr. A. Vaughan from the Upper Seminula-zone (S,) of Burrington Coombe.’ The original source of the various pebbles is not easy to determine. The fragments of grey compact limestones are undoubtedly of Lower Carboniferous age, and the fact that they consist mostly of fairly large pieces suggests that they had not travelled very far. The black limestone, grey oolite, and chert, are also of Lower Carboniferous age; these, however, are smaller and more worn, and may have come from a greater distance. With regard to the vein-quartz, quartzite, volcanic tuffs, ashes, etc., nothing very definite can be said until further study and comparisons are made. ‘The pebbles of this series are well-rounded by wave-action, the majority being no bigger than hazel-nuts. ‘he included fossils comprise an interesting series. They are mostly in the form of casts, but several still retain the greater part of the shell. In most cases only single valves are present. The imperfect state of preservation of some specimens renders precise identification rather difficult, but careful comparison with examples in our own collections and with figures 1 Q.J.G.S., vol. Ixvii, pl. xxviii, figs. 3 and 4, 1911. at Caldon Low, Staffs. 61 in Dayidson’s monograph,’ and in the various papers on the sequence of the Carboniferous Limestone in the British Isles, has enabled us to identify most of the forms. The full list of species, with references, is as follows :— BRACHIOPODA. Orbiculoidea sp. Dielasma hastatum (Sow.). Uarge form. Seminula ambigua (Sow.)? Dav., pl. xv, fig. 16. Athyris cf. expansa (Phil.). Cf. Day., pl. xvii, figs. 3, 3a. Martinia cf. glabra (Mart.). Dav., pl. xiii, fig. 8. M. ovalis (Phil.). Dav., pl. ix, fig. 21. Spirifer bisulcatus (Sow.). Dav., pl. vi, figs. 6-9. S. senvicircularis (Phil.). Dav., pl. vi, figs. 1-5. S. aff. grandicostatus, M’Coy. Davy., pl. viii, fig. 8. ““ Bhynchonella’’ cf. carringtoniana, Dav. Davy., pl. xxiii, figs. 22-20; pl. liii, figs. 1, 2. Orthotetes cf. crenistria (Phil.). Rhipidomella michelini (Li Eveillé). Dav., pl. xxx, fig. 7. Schizophoria resupinata (Mart.). Large forms. Productus corrugato-hemisphericus. Including forms like P. cora, D’Orb., Dav., mut. D; of Vaughan, in Q.J.G.S., 1905, pl. xxv, figs. 4a, b. . cf. giganteus, Day. (non Mart.). Dav., pl. xl, fig. 3. . longispinus, Sow. concinnus, Sow. Cf. mut. De of Sibly, Q.J.G.S., 1906, pl. xxxiii, figs. 3a, b. . martini, Sow. Dav., pl. xliii, figs. 7, Ta. cf. pyxidiformis, De Kon. Dav., pl. xlii, fig. 4. cf. fimbriatus, Sow. Narrow convex forms like Dav., pl. xxxiii, fig. 14c. . fimbriato-pustulosus. punctatus (Mart.). Dav., pl. xliv, fig. 14. . cf. aculeatus (Mart.). Davy., pl. xxxiii, fig. 19. ef. margaritaceus (Phil.). Strongly convex forms near Dav., pl. xliy, figs. 5, 5a. ryt tbh OTHER GROUPS. Phillipsia sp. Pygidium. Lewopteria sp. Bellerophon sp. Phanerotinus ct. nudus (Sow.). Fish-tooth. Cf. Psephodus magnus. ‘Near the top of the section a small, much-weathered, coral of Zaphrentoid type was noticed, but it was impossible to extract it: without considerable damage. The general faunal assemblage would seem to suggest that the forms represented belong to some of the higher beds of the Carboniferous Limestone sequence. As in the case of the pebbles these may all be derived. Comparing the above list with the faunal lists given by Dr. T. F. Sibly for the Carboniferous Limestone of the Midland area,? it will be seen that a number of species are identical, more especially perhaps with those listed for the subzone of Lonsdalia floriformis = De. Highly fossiliferous white limestones without a trace of any pebbles or extraneous material occur in the churchyard at the ' Brit. Foss. Brachiopoda, Part V: The Carboniferous Brachiopoda. Pal. Soe., Lond., 1858-63. 2 Q.J.G.S., vol. Ixiv, pp. 42 et seq., 1908. 62 J. W.Jackson & W. H. Alkins—Quartzose Conglomerate adjacent village of Cauldon, some 300 yards to the north of the conglomerate section. ‘hese beds resemble the ‘‘ Brachiopod-beds” of Treak Cliff and Peakshill, west of Castleton, Park Hill, north of Longnor, and other places in the Midland area, and contain much the same fauna. Unfortunately there are no good exposures of these beds, the material collected by one of us (W. HE. A.) over a period of two or three years having been obtained mainly from grave-shafts in the churchyard and from a small exposure in a field on the south side. According to the 1 inch Geological Survey Map (72 N.E.) the limestone here is cut off from the Pendleside Series by faults on the north-west and north-east sides, but no faults are shown on the south, or Caldon Low, side. Another somewhat similar exposure of highly fossiliferous lime- stones occurs off the main road, opposite the Red Lion Inn, about half a mile south of the conglomerate section. The close proximity of a conglomerate to highly fossiliferous pure limestones recalls similar features elsewhere in the Midland area, especially in the neighbourhood of Castleton. A rolled-shell and limestone-pebble conglomerate has long been known in the latter area, and seems to lie at, or near, the top of the Zonsdalia-subzone =]),. Itis well seen on the eastern side of Cave Dale, Castleton, immediately above the limestone bluffs, beyond the second mineral vein (Faucet Rake?). The dip of the beds here is 30° N.N.W., and in addition to worn and fragmentary valves of Productus ‘‘ giganteus ” the conglomerate contains rounded pebbles of limestone, nodules of oolitic chert, and fragmentary corals. An imperfect tooth of Petalodus was also obtained here by one of the writers (J. W. J.). A further exposure of the conglomerate is seen at the foot of Cow Low, west of Castleton village. Here the beds dip at 15° N.W., and consist principally of abundant water-worn and rolled shells of Productus ‘‘giganteus’’. It extends westwards to the entrance to the Winnatts, near the Speedwell Mine, and is again seen in a quarry at the foot of Treak Cliff, where the beds dip at an angle of about 20° N.N.E. The conglomerate here contains much crinoid debris, large Productids, Spirifer bisulcatus, etc., and in the succeeding flaggy limestones (also in part conglomeratic) numerous fish-teeth, especially Petalodus, and the spines and plates of Archeocrdaris, are to be found. The conglomerate is apparently cut off from the famous ‘‘ Brachiopod-beds” of Treak Cliff by a fault running N.N.W. to S.S.E. from the Odin Mine to the Winnatts. It reappears, however, near Windy Knoll, where limestone pebbles and oolitic erains form a prominent feature; chert is also associated with it, as at Cave Dale. Similar conglomerates are to be seen at Barmoor Quarry, near Sparrowpit, and at Glutton Dale, north of Longnor. Along with the shell-debris (Spirifer bisulcatus, etc.) and fish-teeth (Psammodus, Psephodus, Petalodus, etc.) at the Sparrowpit locality, a fairly large amount of quartz of a well-rounded character is said to occur." 1 Trans. Manchester Geol. Soc., vol. xxv, p. 125, 1896. at Caldon Low, Staffs. 63 The only record of a rolled-shell conglomerate on the eastern side of the limestone massif appears to be that of Cracknowl quarry, near Hassop Station.* It is interesting to note that Dr. Sibly* and Mr. C. B. Wedd* have described sections in the eastern part of the Midland area which afford evidence of local earth-movement and erosion in Upper Carboniferous Limestone times. One section is near Youlgreave, the other at Darley Bridge. The limestones in these sections are regarded as representing a high level in the Lonsdalva-subzone, and in both cases black shales, presumably of Pendleside age, clearly overstep their denuded edges, thus causing local unconformity. It is not improbable tHat the formation of the shell and limestone- pebble conglomerate of Castleton and other places was contem- poraneous with the earth-movement and erosion which produced these unconformities. . In addition to the main unconformity near Youlgreave, Dr. Sibly also points out the probability of further contemporaneous elevation and erosion during the formation of the Upper Zonsdalia-beds, as in the lower part of the section the truncated edges of a series of limestone-beds form a surface upon which rests another series of beds, less steeply inclined. In the North Wales sequence Dr. Wheelton Hind and Mr. J. T. Stobbs have described a similar phenomenon to that of Youlgreave in the upper beds of the Carboniferous Limestone seen in Waenbrodlas Quarry, Halkyn Mountain (Flintshire).4 At or about the same horizon (D2) in other localities in North Wales the same authors record the occurrence of a conglomerate with quartz-pebbles succeeding a Productus giganteus-bed. The absence of sections at Cauldon renders it difficult to ascertain the relationship of the quartzose conglomerate to the limestones containing a fauna typical of the Brachiopod-beds of Castleton. Consequently, at the moment, it is not possible to correlate with absolute certainty this conglomerate with that of Castleton and other places. The contained fauna seems to suggest that it may be contemporaneous, and if so there appears to be a considerable gap between it and the Humerosus-beds of Caldon Low. The age of the latter beds is a subject upon which some difference of opinion prevails. Dr. Sibly, in 1908,° regarded them as probably belonging to the upper part of D,, while others, including Dr. Wheelton Hind, are inclined to place them much lower in the sequence, viz. C—S,.° In this connexion it will be of some interest to record the discovery by one of the writers (J. W. J.) of an interesting coral recently in 1 Elizabeth Dale, The Scenery and Geology of the Peak of Derbyshire, 1900, p. 17. 2 Op. cit., 1908, p. 63, and fig. 5 (p. 62). * Discussion of Dr. Sibly’s paper, op. cit., p. 81, and Mem. Geol. Sury., The Geology of the Northern Part of the Derbyshire Coalfield and Bordering Tracts, London, 1913, p. 35. + Grou. MAG., N.S., Dec. V, Vol. III, p. 396, Pl. XXII, 1906. > Q.J.G.S., vol. lxiv, p. 44, 1908. 6 GEOL. MAG., Dec. VI, Vol. V, p. 480, October, 1918. 64 J. W. Jackson & W. HE. Alkins—Quartzose Conglomerate. these beds. ‘This may prove of some assistance in arriving at the precise age of the limestones in question. ‘he specimen, which is unfortunately rather imperfect, was obtained from a large block of limestone in a quarry worked for road-metal on the western side of the Low, midway between the Red Lion Inn and Cauldon village. Other blocks in this quarry contained numbers of Chonetes ct. comoides, Bellerophon, and Productus humerosus (P. sublevis) of two forms—one strongly convex and narrow with a broad shallow depression down the centre of the back;' the other broader and flatter with a similar depression down the back, from which later on a low central ridge bearing spine-bases arises: these spine-bases are also visible on the umbonal portion of the depression, and on the ears.” The coral, which consists almost entirely of the calix, is distinctly Caninoid in character, and measures about 32mm. in diameter. It is apparently closely related to Caninia cylindrica, mut. 8), as figured by Dr. Vaughan in 1905.* Regarding Productus humerosus (= sublevis) Dr. Vaughan states * that in the Franco-Belgian area an early smooth form occurs at the top of Cz. In the South-Western Province this form is very rare, but is recorded from the Cs-oolite of Burrington. In the Clitheroe region this early form enters at the top of C, and forms a persistent band at the top of C, (asin Belgium). Productus cf. sublevis is also recorded from the Lane Limestone (co. Dublin) = C,. This lime- stone underlies the Lane Conglomerate = C,, and both were formerly regarded as D.° Most of the Caldon examples we have seen agree closely with Vaughan’s figure of the early form from the Franco- Belgian area,’ and with a specimen from Twiston, Lancs, in the collection of one of the writers (J. W. J.); but there is the broader spinous form to be considered. It is unfortunate that more definite conclusions cannot be given as to the age of the quartzose conglomerate and its relation to the Humerosus-beds of Caldon; but we are hoping that, in the near future, quarrying operations will expose further sections which will provide us with more conclusive evidence. The material dealt with in this paper will be deposited for future reference in the Manchester Museum. 1 Cf. Q.J.G.S., vol. lxxi, pl. vii, fig. 8, September, 1915. 2 Cf. Davidson, Monograph, pl. li, figs. 1, 2. The original of fig. 2 is stated by Davidson, p. 234, to have been found at Caldon Low. 2 Q.J.G.S., vol. lxi, pl. xxiii, fig. la, 1905. 4 Q.J.G.S., vol. Ixxi, p. 47, 1915. > L. B. Smyth, Scient. Proc. Roy. Dublin Soc., N.S., vol. xiv, No. 41, August, 1915. SONGS. vol. lxxig ple wil, te. 8) Ola. L. F. Spath—WNotes on Ammonites. 65 IV.—Novrrs on AMMONITES. By L. F. Sparu, B.Sc., F.G.S. (Continued from p. 35.) ch eae) OBLIQUITY OF THE SUTURE-LINE. CHARACTER of the suture-line that has received considerable Ws attention lately is the obliquity with regard to the radius. Of course, it had long been noticed that suture-lines may vary in the form and foliation of their elements (brachyphyllic, dolchophyllic, and leptophyllic suture-lines of Mojsisovies,’ and euryphyllian and stenophyllian suture-lines of Haug’) as in their general course. There may be (externally) a strong convexity forward ( Cyclolobus), a straight (Sphenodiscus) or wavy line (Pseudosageceras), or a con- vexity backward (Protengonoceras). Again, the suture-line may be inclined strongly forward towards the umbilicus (Cheltonia) or have a retracted or dependent inner portion (Pszloceras). It is this latter obliquity that has been used as a generic and even family distinction, e.g. by Mr. Buckman,’ to determine the affinity of Bredya with Hammatoceratide, and not Hildoceratide. On a previous oceasion* when dealing with the ‘‘suspensive lobe”? (dependent auxiliaries) of Pszloceras. and its ancestors, the writer expressed the opinion that its significance was doubtful. Since then the dissection of a number of Ammonites showing this obliquity of the suture-line towards the umbilicus, e.g. Derocerates, and the developing of the whole of their external and internal suture-lines has confirmed his belief in the impossibility of using this variable character—like the above-mentioned divisions proposed by Mojsisovics and Haug—even for generic distinctions. Mr. Buckman, in his Monograph of the Inferior Oolite Ammonites,’ figures on pl. A, fig. 29, the suture-line of a Hzldocewas that has a strongly ascending inner portion as compared with the type given in fig. 28. Waehner® has shown that dependent auxiliaries are neither always present in Ps¢loceras, nor always absent in Arvetites. Tornquist’ figures suture-lines of Pictonie that show the typical descent towards the umbilicus and others that are straight. And it may be recalled here what R. Douvillé® says concerning the genus Macrocephalites: ‘‘ As regards the more or less great obliquity of the 1 ““ Die Cephal. d. Hallstatter Kalke ’’: Abh. k.k. Reichsanst., vol. vi, p. 2, 1873-93. 2 **Ties Amm. du Permien et du Trias’’: Bull. Soc. Géol. France, ser. III, vol. xxii, p. 409, 1894. 3 “Certain Jurassic (Lias-Oolite) Strata of South Dorset; and their Correlation’: Q.J.G.S., vol. lxvi, pp. 97-8, 1910. + “* Development of Tragophylloceras Loscombt’’: Q.J.G.S., p. 352, 1914. ° Pal. Soc., vol. i, 1887-1907. 6 “ Beitr. Kenntn. Tief. Zonen Unt. Lias Nordéstl. Alpen ’’: Beitr. Geol. Pal. Osterr.-Ung., vol. iv, pts. iii, iv, pp. 190-202. “ “‘Nie Degenerierten Perisphinctiden des Kimmeridge yon Le Havre’’: Abh. Schweiz. Pal. Ges., vol. xxiii, p. 41. 8 ““Hitude sur les Cardioceratidés de Dives, etc.’’?: Mem. No. 45 Soc. Géol. France, Pal. i, 19, fase. ii, p. 14. DECADE VI.—VOL. VI.—NO. II. 5 66 L. F. Spath—WNotes on Ammonites. suture-line in relation to the radius, it seems to vary with time in the whole group, as has recently been shown by Lemoine (1910). The same thing is noticed in Pachyceras and Tornquistes, where the most recent forms have the most inverse suture-lines. We have to do here, therefore, rather with a general phenomenon, appearing in a parallel manner in the different branches of a given family, or even in fairly distant groups, than with a special character peculiar to a single branch, and permitting us, consequently, to follow it through time. In this connexion it may be called to mind that in quite another group of Ammonites, in S¢mbirskites of the Lower Cretaceous, identical and exactly contemporaneous forms may have either a normal or a freely inverse euture-line (S. enversus and subinversus). It does not seem, therefore, that this character of an oblique suture-line has very great importance.” It might be thought that the character of the umbilical edge or slope, and its ornament, could affect the position of the auxiliaries, but the evidence in favour of this is not satisfactory. One should not find in identical smooth oxycones, with an exactly similar, rounded, umbilical edge, suture-lines that may be either concave forwards or convex, either rising or descending towards the umbilicus. But in, e.g., Cheltonia, the extremely oblique and almost tangential suture-line of the sides is compensated for by a very deep internal lobe, and the variation in the course of the suture-line does not appear to affect the convexity of the septum as a whole. It may be recalled here that the deposition of calcium- carbonate, as in the recent WVautilus, probably began at the sides of the shell, i.e. in the region farthest removed from the siphuncle, so that dependent auxiliaries near the umbilicus suggest less penetration posteriorly of the attaching fibres of the lobes. Swinnerton & ~ Trueman (p. 36) give two Gmberestine illustrations of incomplete septa in Dactylioceras and Polymer plates. They show that the septa were indicated in all sutural details, and though only formed in part were situated at the normal distance from the preceding septa. The functions of the septal edge are not impaired by the ‘variation of its course or curvature, therefore, and the comparative insignificance of the obliquity is realized when the external and internal’ suture- line is considered as one whole. That in a Lioceras* direction and curvature may vary within the same species, and that in Pszloceras* even in the same individual, first a complex suture-line with dependent inner lobes, and at the end a simple one with ascending 1 The presence of a high internal saddle in certain Japanese Scaphites induced Yabe (“* Die Scaphiten a. d. Oberkreide von Hokkaido’’: Beitr. Pal. Osterr.-Ung., etc., vol. xxiii, p. 167, 1910) to create a new genus, Yezoutes ; but the writer would agree with Nowak (in ‘‘ Untersuchungen ti. Cephal. Ob. ~Kreide in Polen’’, ii, Die Skaphiten: Extr. Bull. Acad. Sci. Cracovie, July, 1911, p. 549), who cannot admit that the internal portion of the suture-line of Ammonites is the most important as regards the determination of their relations, though ‘‘ it must not be underestimated or, still less, neglected, as is still done very often at the present day ’’. 2 Horn, ‘‘ Die Harpoceraten der Murchisone-Schichten des Donau-Rhein- Zuges’’: Mitt. Grossh. Bad. Geol. Land. Anst., vol. vi, pt. i, p. 264. * Neumayr, ‘‘Kenntn. Fauna Unterst. Lias i. Nordalpen’’: Abh. k.k. Reichsanst., vol. vii, pt. v, p- 25, pl. iv, figs. 6a, b, 1879. L. F. Spath— Notes on Ammonites. 67 auxiliaries may be found, shows the unimportance of this character for classificatory purposes, even if, occasionally, it be constant in a group of forms. Workers on Ammonites recognize that the details of the suture- line may vary greatly in a given species. Noetling,’ e.g., in his research on the suture-line of Pseudasageceras multilobatum, examined many specimens, but found no two suture-lines alike. On pl. xxvu, e.g., he figures forty-eight suture-lines, arranged in six groups, and showing a great variability both in the ventral and in the first lateral lobes. Pompeckj* thinks that Oxynoticeras oxynotum presents as many varieties. On the other hand, the writer® found that the suture-line of young specimens of Zragophylloceras Loscombi was very constant, and that the only variability noticed was in relation to the degree of complication at a given size; whereas in larger examples, again, no two suture-lines were exactly alike. This only confirms that the development of the suture-line should be studied, from its first, angustisellate beginning, and when this, in conjunction with the development of all the other features of the shell, is used as a basis for classification, variability within a species will prove no obstacle. That in Phylloceratide and Lytoceratide neither this variability and obliquity, nor the features of instability already referred to, are apparent, seems to the writer of some significance. SpacInG OF THE NSEPTA. Hyatt stated ‘+ that the septa ‘‘ vary exceedingly in number among different species and also at different ages of the same individual, but they are tolerably constant, as a rule, within the limits of one and the same species, if specimens of the same age are compared. They follow one another in regular succession, but, as observed by Hyatt, the intervals are relatively greater in the young, more constant in the adult, and then markedly decrease in the oldest stage of development”. Bather, before Hyatt, had been more definite, and stated that the ‘‘ radio of the normal septal intervals was constant in any given shell, while the approximation of the last septa was a geratologous character’’.° Blake® remarked with regard to the latter statement that ‘‘if any law could be founded on this and applied to phylogeny, we should not find the ratio of the second chamber to the first so variable as Barrande has shown it to be, nor should we find approximate septa in the early Orthocerata, nor crowded sutures in Ammonites at their acme’’. Both in Nautili and in Ammonoids there are many irregularities in the spacing of the septa. Mr. Crick’ mentioned ‘‘two Wautilc ! Paleontographica, vol. li, pts. v, vi, p. 259, 1905. 2 ‘Notes sur les Oxynoticeras du Sinémur. Supér. du Portugal, etc.’’: Comm. Serv. Geol. Portug., vol. vi, pt. ii, p. 219, 1906. 3. Op. cit., 1914, p. 346. 4 Op. cit., i, p. 510, 1900. > “The Growth of the Cephalopod Shells’?: Grou. MaG., Dec. III, Vol. IV, pp. 446-9, October, 1887; and ‘‘ Shell-growth in Cephalopoda (Siphonopoda)’’: Ann. Mag. Nat. Hist., ser. vi, vol. i, pp. 298-310, April, 1888. 6 “The Evolution and Classification of the Cephalopoda, an Account of Recent Advances ’’: Proce. Geol. Assoc., vol. xii, p. 291, 1892. 7 Proc. Geol. Soc., No. 979, p. 3, November 11, 1915. 68 L. F. Spath—Notes on Ammonites, from the Upper Cretaceous Rocks of Zululand. Hach showed approximation of the last three septa .. . One specimen showed also irregularities of depth in the other chambers of the camerated part of the shell”. Foord’ figures two Inferior Oolite Wautili (NV. pseudolineatus and IV. polygonalis), one of which has the last septum closer than the usual interval, the other has it more distant. A fair. amount of variability as regards the spacing of the septa (especially the last) is also found in Paleozoic genera, e.g. the Middle Devonian forms referred to ‘‘Gomphoceras’’ by Cleland.* In Wisconsin this genus is found not only in great abundance as regards the number of individuals, but is also represented by a variety of more or less closely related species, which rather suggests favourable conditions. In Bohemia also, where the Silurian period produced an exceedingly rich Cephalapod fauna, this variability prevails, as is shown in Barrande’s classical work.’ As regards Ammonites, the irregularity is even more striking. A. E. Trueman‘ has recently figured some Polymorphites that show approximation of the last septa. This seems to be an unstable genus of generally small and very variable forms of limited horizontal distribution. But in Aildoceras bifrons, which species-group, with horizontal variants and vertical mutations, is found in North- Western Europe, in the Alpine-Mediterranean-Pontian province, and as far as Japan, the phenomenon is observed, as well as in its probably benthonic and often one-sided derivative Mechiella. Among fifty-six specimens of Amioceras niger (Blake), i.e. of another universal genus, that the writer examined, six specimens had their suture-lines fairly distant, and in five more the distance was some- what less. Twenty-seven specimens had the septa a medium distance apart; in five they were fairly close, and in thirteen very close together. Besides, there were irregularities in almost every specimen, many of them showing closer septation after a fairly distant beginning. On thirty-one specimens the last sutures were well displayed, and here even greater irregularity was noticed. In one specimen there was no approximation at all, and in.two more it was only just noticeable. Nine specimens had the last two suture-lines fairly close, in three more they were very close. In eight specimens there was approximation of the last three septa; in one the last four suture-lines were fairly close, and in another they were very close together. One specimen had the last five septa closer than the previous ones, but they were equidistant from one another, whereas in another specimen the last five septa were gradually approxi- mating. ‘wo more specimens had the last six suture-lines gradually vetting closer, and finally, in another two there was first 1 Op. eit., vol. ii, p..214.) 2 « MINERALOGICAL MICROSCOPES. Dr. A. HUTCHINSON’S UNIVERSAL GONIOMETER. University. Optical Works, | $81 TOTTENHAM COURT ROAD, LONDON, W. 1. pearson s Microscopes for Geolozy- WATSON & SONS manufacture a special series of Microscopes for Geo- logical work. All have unique features, and every detail of construction has been carefully considered with a view to meeting every requirement of the geologist. All Apparatus for Geology supplied. WATSON’S Microscopes are guaranteed for 5 years, but last a lifetime, and they are all - BRITISH MADE at BARNET, HERTS. W. WATSON & SONS, Ltd. ‘£STABLISHED 1837) 313 HIGH HOLBORN, LONDON, W.C.1 Works:—HIGH BARNET, HERTS. THE GHOLOGICAL MAGAZINE NEWO SERIES) DECADE Vin: VOL VW Ni No. III.— MARCH, 1919. EDITORIAL NotTHs. '%,, \ ITH the present number a new feature is introduced into — Y the Grorocicat Macazine, namely, an Kditorial page. Hitherto announcements of events of current interest have been relegated to a section with the somewhat unsatisfactory title of ‘‘ Miscellaneous” and have been confined within rather narrow limits. The intention is to extend this feature into the form of Editorial notes and comments on topical matters, personal, academic, administrative, scientific, and economic; in fact, any subjects bearing on the development and progress of geology at home and abroad. It is hoped by this means to extend the usefulness of the Magazine and to interest a still wider circle of readers by affording an opportunity for a free and informal discussion of the problems of the day. This is a period of altogether exceptional conditions and also, it is believed, the dawn of a new era in the history of science in general and of geology in particular. In order that geology may play its part in the great work of reconstruction that les before us a wide dissemination of ideas is essential, and, without being unduly egotistical, it is the ‘hope of the Editors that the Grotoarcan Macazinz may take a humble share in this great task. Mr. Atrrep Harker, M.A., LL.D., F.R.S., has been appointed Reader in Petrology in the University of Cambridge. There is at present no permanent Readership connected with Geology in the University, but ‘‘having regard to the long service and scientific achievements of Mr. Harker” it was decided that a special Reader- ship should be established for him, the appointment to date from January 1, 1919. * % Be Art the annual meeting of the Geological Society, held on February 21, the officers for the ensuing year were elected as follows: President (for the second year), Mr. G. W. Lamplugh; Vice- Presidents, DECADE VI.—VOL. VI.—NO. III, 7 98 Editorial Notes. Professor J. E. Marr, Sir Jethro Teall, Mr. R. D. Oldham, and Sir John Cadman; Secretaries, Dr. H. H. Thomas and Dr. H. Lapworth; Treasurer, Dr. J. V. Elsden; Foreign Secretary, Sir A. Geikie. The following were also elected to replace the five retiring members of Council: Dr. G. T. Prior, Professor P. F. Kendall, Dr. G. Hickling, Mr. A. Howe, and Mr. R. 8. Herries. % % % % % In view of the change in the political status of women brought about by the new Franchise Act it was inevitable that the question of their admission to the Geological Society should again be brought forward. In this connexion the award of the Murchison Medal to Miss G. L. Elles, as recorded last month, is significant. At the meeting of the Society on January 22 the President announced that a special general meeting will be held on March 26 to consider the following motion : ‘‘That it is desirable to admit women as Fellows of the Society.” There can hardly be any doubt as to the outcome of the discussion, and we may hope that a long-delayed measure of justice will be carried out without serious opposition. % 2 2 * % Messrs. Grorce AtLen & Unwin, Lrp., have done a useful service by publishing, under the title of German Designs om Trench Lorraine, a translation, with introduction, of the secret memorandum presented by the German iron and steel manufacturers to the Imperial Chancellor and to Field-Marshal von Hindenburg at the close of 1917. This is a document of remarkable interest in many ways, partly as an exposition of German unscrupulousness and cynical disregard for truth and partly as an example of how completely a case may be given away by excess of zeal. Since the main points brought forward are essentially matters of geological fact, distorted to suit German arguments, it may be briefly summarized here. The gist of the argument is as follows: Germany will require, after a peace victorious for the Central Powers, a greatly increased supply of iron and steel: her home supplies are approaching exhaustion, therefore it will be necessary for the continued existence of the Empire, and especially for the successful prosecution of the next war, to annex that part of Lorraine which still remains French. In order to diminish the atrocity of this annexation, the reserves still remaining in Germany are much under-estimated, while the amount of the supplies available in the rest of France are multiplied enormously. ‘The figures given are stated to be on the authority of the well-known geologists Beyschlag and Krusch. These authorities value the average life of the German mines at 40 to 50 years. According to the best pre-War figures the German resources were in 1910 about 3,900,000,000 tons of ore: if this is to be exhausted Editorial Notes. 99 in 50 years it would correspond to an average yearly production of 35,000,000 tons of pig iron from home ores alone, without counting imports, an apparently impossible figure, and more than double the pre-War production. ‘The figures given for France are still more startling. In 1916 a German engineer estimated the resources of Normandy at 500,000,000 tons of ore, but the authors of this memoir adopt the figure of 5,000,000,000 tons for this area, or ten times as much. As a subsidiary argument the urgent need for phosphatic manures, i.e. basic slag, for German agriculture is insisted on, and this can best be obtained from the Lorraine ores. This memorandum in point of fact proves in the clearest possible manner that without the Lorraine iron-fields the German Empire can never again conduct a great European war, and the general impression left on the mind of the non-political reader is that the one thing that really matters at the present Peace Conference is the restoration of Lorraine to France; without this iron-field Germany, on her own showing, is helpless for good or evil for evermore. This is of course an exaggerated view of the case, nevertheless it is clear that the matter is of paramount importance, and it is much to be hoped that the geological aspect of it has been duly placed before the responsible authorities. 2 * % % % Tux issue of Nature for January 16, 1919, contains a valuable article by Mr. V.C. Illing on Borings for Oilin the United Kingdom. The whole subject is reviewed from an eminently practical and common-sense point of view; while due weight is given to the admitted occurrence of petroleum in small quantities in many British localities, especially in the Carboniferous, these are reduced to their true proportions, which are shown to be insignificant, and the author evidently entertains no hope of a commercially successful result from the investigations now proceeding. The article should be read in conjunction with the memoir on this and cognate subjects recently issued by the Geological Survey, which likewise pours floods of cold geological common-sense on the rosy optimism which has lately been prevalent in the columns of the daily press. Such a treatment of the subject was much needed, since the indulgence of such hopes can, in the opinion of competent geologists, only lead to disappointment. Although the scheme now in operation in Derbyshire is on a some- what higher plane than the famous leaky tank at Ramsey, neverthe- less if is to be gravely doubted whether the results will be of much more practical value. It is of course possible, however, that these extensive borings may yield other results of unlooked-for scientific or economic importance, apart from the problematical supply of liquid fuel. ORIGINAL ARTICLIHS. —>>———_ I.—Fosstz Fisors In THE Dervontan Rocxs or Norta Devon. By INKERMANN ROGERS. HE Devonian rocks in Devon, like those of the Old Red Sandstone of which they are the equivalents, have been divided into three groups. Mr. T. M. Hall,’ writing in 1879, quoted no less than five separate classifications suggested for the beds of North Devon, nor has uncertainty been removed by the conclusions arrived at by geologists since that date.? But we may for present purposes take the following as the nearest approach to a generally accepted succession :— Yi f Pilton Beds. Baggy Beds. Ua) EVOL Pickwell Down Sandstones. Morte Slates in part. Morte Slates in part. Ilfracombe Beds. Hangman Grits. LOWER DEVONIAN 5 Lynton grits and shales. Foreland grits and shales. MIDDLE DEVONIAN While examining the rocks of the Middle and Upper series for fossil plants during the past eleven years (1907-18), the results of which have already in part been published,* other discoveries were made incidental to the work of collection of plant remains. Among these the discovery of fossil fish remains seems worthy of special notice. The object of this brief note is to describe the discovery of fossil fishes made by the writer in the Pickwell Down Sandstone within a few hundred yards of the junction beds of the Morte Slates. As far as he has been able to ascertain, it is with one exception the only find of such remains made in any of the North Deven rocks classified above as Upper Devonian. The exception is a scale of Holoptychius 17. M. Hall, “‘ Classification of the North Devon Rocks’’: Trans. Devon Assoce., vol. xi, pp. 180-90, 1879. 2 J. B. Jukes, ‘‘ On the Carboniferous Slate (or Devonian Rocks) and the Old Red Sandstone of South Iveland and North Devon’’: Q.J.G.S., vol. xxii, p. 320, 1866, and his pamphlet, Additional Notes on the Grouping of the Rocks of North Devon and West Somerset (privately printed), Dublin, 1867 ; R. Etheridge, ““On the Physical Structure of West Somerset and North Devon’’: Q.J.G.S., vol. xxiii, p. 568, 1867; W. A. EH. Ussher, ‘* On the Paleozoic Rocks of North Devon and West Somerset’’: GEOL. MaG., Dec. II, Vol. VIII, 1881, and “‘ Cornwall, Devon, and Somerset’’: Jubilee Volume Geol. Assoc., 1910, p. 859; J. KH. Marr, “* On some Effects of Pressure on the Devonian Sedimentary Rocks of North Devon’’: Grou. MaG., Dec. III, Vol. V, 1888; H. Hicks, ‘‘ On the Morte Slates and Associated Beds in North Devon and West Somerset’’: Q.J.G.S., vol. lii, p. 254, 1896, and vol. liii, p- 441, 1897; Rev. G. F. Whidborne, ‘‘ Preliminary Synopsis of the Fauna of the Pickwell Down, Baggy, and Pilton Beds’’: Proc. Geol. Assoc., vol. xiy, pt. ix, p. 371, 1896. 3 Arber & Goode, ‘‘On some Fossil Plants from the Devonian Rocks of North Devon’’: Proc. Camb. Phil. Soc., vol. xviii, pt. iii, p. 89, 1915. Inkermann Rogers—Fossil Fishes from North Devon. 101 referred to by Professor J. Phillips in his Paleozoie Fossils,’ published in 1841, as having been discovered at Baggy Point. On the shore at Woolacombe Sands, about a quarter of a mile ‘south of Woolacombe, an isolated patch of Pickwell Down sandstones and shale, dipping to the south at an angle of 60°, projects seaward from the foot of the sand-dunes. This outcrop, which is locally known as Mill Rock, measures 60 feet by 50 feet, and rises from 6 to 7 feet above the level of the tidal sands. Ihave not seen it myself, but Mr. J. G. Hamling, F.G.S., who has visited the spot, informs me that the exposure is fragmentary and covered by ‘‘ head”. In the year 1913 Dr. Thomas Young, of Colyton, then of Woolacombe, called my attention to there being an igneous vein about 2 inches thick in Mill Rock. JI obtained a sample of it and recognized it as voleanic tuff. Eastward the vein is met with in a rock cutting leading to a large quarry opposite Fox Hunter’s Inn on the Braunton road, three miles from Woolacombe. Here it is 18 inches in thickness and badly weathered. ‘Three miles still further eastward it is well exposed in an old quarry a little south of Bittadon. Here the bed is 25 feet thick, fully crystalline, and much weathered. Mr. Ussher,? and also T. M. Hall,? refer to it as the Bittadon felsite. Tt extends to Bratton Fleming, another six miles eastward. Here I have not seen it myself, but Mr. Hamling, F.G.S., who has, informs me that it is fragmentary and probably not more than two or three inches in thickness. Recently (May, 1918) I polished a piece of the tuff from Mill Rock. On closely examining it I detected to my surprise what appeared to be fish-remains and a tooth, whereupon I determined to obtain further samples of the rock. The result was I found not only that there were fish remains in the tuff, but that fragments of bones and teeth could be observed in almost every part of Mill Rock. One lenticle of redeposited tuff mingled with shale was discovered containing several scales, portions of scales, and bone plates, as well as many small bones. These proved to be the remains of typical Upper Devonian fishes — Holonema, Bothriolepis, Holoptychius, Polyplocodus. All the specimens were forwarded to Dr. A. Smith Woodward, F.R.S., for examination, and he has kindly sent me the subjoined report. 1 J. Phillips, Figures and Descriptions of the Paleozoic Fossils of Cornwall and Devon and West Somerset, p. 1383, 1841. See also Rev. D. Williams, ‘“On the Killas Group of Cornwall and Devon’’: Trans. Roy. Geol. Soc. Cornwall, vol. vi, pp. 122-38, 1843; R. Etheridge, ‘‘On the Physical Structure of West Somerset and North Devon’’: Q.J.G.S., 1867, p. 156; W. Pengelly, ‘«The History of the Discovery of Fossil Fish in the Devonian Rocks of Devon and Cornwall’’: Trans. Devon Assoc., vol. ii, pt. ii, p. 423, 1868; J. G. Hamling, ‘‘ Recently Discovered Fossils from the Lower and Upper Devonian Beds of North Devon’’: ibid., vol. xl, pp. 276-80, 1908; ‘’ Excursion to North Devon, Easter, 1910’’: Proc. Geol. Assoc., vol. xxi, pt. ix, 1910. 2 W. A. E. Ussher, ‘‘ On the Palmozoic Rocks of West Somerset and North Devon’’: Proc. Som. Arch. and Nat. Hist. Soc., 1879, and ‘* Cornwall, Devon, and Somerset’’: Jubilee Volume Geol. Assoc., 1910, p. 869; T. M. Hall, ‘‘ Geology of the Ilfracombe Coast-line’’?: Trans. Devon Assoc., vol. xi, p. 278, 1879. 102 Inkermann Rogers—Fossil Fishes from North Devon. Norrs on THE Fisa-REMAINS FROM THE PIcKWELL Down SANDSTONES. By A. SMITH WOODWARD, LL.D., F.R.S. The fish-remains discovered by Mr. Inkermann Rogers in the Pickwell Down Sandstones of Woolacombe Bay are merely scattered fragments. Some are sufficiently well preserved to exhibit their microscopic structure, but many are much obscured by the ferruginous infiltrations in the rock. A few appear to be generically determinable. Hotonema cf. ornatum, Traquair.—The most important specimens are two portions of dermal plates with an ornament much resembling that of the armour from the Upper Old Red Sandstone of Shetland named Holonema ornatum by Traquair. The larger fragment is about as broad as long (measuring 9 cm. each way), but its borders are incomplete; and in both specimens the ornament is obscured by ferruginous stains which cannot be removed. The greater part of the plate is covered with low and rounded vermiculating ridges, which sometimes blend into a network; and the margin, to the width of about 2cm., is ornamented with finer and closer straight ridges which are directed mainly at right angles to the edge. here are also some vague traces of tubercles on or between the ridges. ‘The middle part of the larger specimen is 5mm. in thickness; and a microscope-section of the smaller specimen shows that all the tissue is well preserved except that of the superficial ornament. The calcification is in almost structureless lamellae, without bone-cells, and there are numerous irregular, horizontally-extended spaces between the lamelle which give the plate a very open texture. The spaces are evidently all connected, for straight vertical canals are often conspicuous crossing the lamelle. The structure of the plate is therefore similar to that of the Ostracoderms Psammosteus and Drepanaspis,? and very different from the true bone of Arthrodiran armour. This fact, indeed, suggests doubts as to whether the Shetland end Devon fossils are rightly ascribed to Holonema; for, although the microscopic structure of the original specimens of this genus from the Upper Devonian of North America remains unknown, the arrangement of the plates, so far as discovered, corresponds most closely with that of such an Arthrodiran as Coccosteus. Borurioteris.—The proximal end of the articular plate of an appendage and the remains of a posterior ventro-lateral plate belong to an Asterolepid, which other fragments of ornamented dermal armour seem to identify with Bothriolepis. The structure of the ventro-lateral plate, sofar as preserved, agrees with that of the latter genus. The ornament of the other fragments is a coarse network of rounded ridges which often rise into low tubercles or are even subdivided into separate tubercles. In one specimen the most prominent ridges are concentric with the margin of the plate. 1 Trans. Roy. Soc. Edinb., vol. xlvi, p. 327, pl. ii, 1908. 2 J. Kier, Rep. 2nd Norwegian Arctic Exped. Hram, 1898-1902, No. 33, pp. 28, 30, 35, text-figs. 5, 6, 8, 1915. Prof. Swinnerton—The Facial Suture of Trilobites. 103 Some portions of the Asterolepid cancellous tissue belong to plates of considerable thickness. They may perhaps represent a Bothriolepis with a large dorsal crest, such as has been described by Traquair in a species from the Upper Old Red Sandstone of Elgin,’ Hotorrycurus.—One Holoptychian scale, shown in impression, is ornamented with very coarse rounded ridges, which are closely arranged and are not subdivided into tubercles. Another specimen, in which only a fragment of the original scale remains, shows by a clear impression that the inner face is destitute of a median tubercle. PotyrLocopus.—There are several isolated small Rhizodont teeth, which agree with those from the Upper Devonian of Russia and Scotland commonly named Polyplocodus.2 They are not compressed to sharp edges, but rounded in section, and their outer face is marked by fine vertical grooves or striations. A microscope-section of two specimens shows the typical Rhizodont structure, and one broken tooth proves that the pulp-cavity extends upwards nearly to the apex. Part of the impression of one of these teeth is seen in a piece of Bittadon felsite. Coccostran.—Some portions of tuberculated plates are probably Coccostean, but not sufficient for exact determination. Concruston.—The fish-fauna represented by the fossils from the Pickwell Down Sandstones is therefore typically Upper Devonian. Il.—Tue Facrat Survre oF TRILosires. By Professor H. H. SWINNERTON, D.Sc., F.G.S., F.Z.S., University College, Nottingham. InrTRopucTION. fVVRILOBITES in common with all other Arthropods shed their more or less rigid external covering or exoskeleton periodically. To accomplish this ecdysis it is necessary for this covering to split somewhere; and it is highly probable that the facial suture was the line along which such splitting took place. There seems, however, to be a tendency to assume that all lines which served this purpose are homologous. This has introduced unnecessary difficulties into the study of Trilobite classification. The object of this paper is to do something towards the elimination of this source of error. THe SEGMENTATION oF THE Heap. A consideration of the segmentation of the cephalon will do much to give precision to our ideas of the position and homologies of the facial suture. ; Bernard? considered that the number of segments in the head region was not fixed, and that within the order Trilobita new ' Bothriolepis cristata, R. H. Traquair, Fishes of the Old Red Sandstone (Mon. Pal. Soc., 1906), p. 130, pl. xxxi. 2 See R. H. Traquair in Brown & Buckley’s Vertebrate Fauna of Moray Basin, 1896, p. 257. °H. M. Bernard, ‘‘The Systematic Position of Trilobites’’?: Q.J.G.S., vol. 1, p. 414, 1894. 104 Professor H. H. Swinnerton— segments had been added to the posterior margin. He based this view upon two considerations: first, that the number of segments indicated on the axial portion of the dorsal side of the cephalon varied; second, that the last or occipital segment bears so close a resemblance to a trunk segment as to suggest that it had ‘been recently incorporated”’. In discussing the former consideration, he observes that whilst the majority of trilobites show traces of five segments on the glabella, some, e.g. Muicrodiscus and TZriarthrus, show only four. This line of reasoning is fallacious, for glabellar furrows are often reduced or smoothed out, so that if indications of four segments are left it is not safe to say that there are not more than four segments in the head, but it is safe to say that there are at least four. The presence of five segments on the glabella of Hodzscus speciosus* and the discovery since his day of five pairs of cephalic limbs in Triarthrus refute his first argument. a b Tpeutes showing the position of the ‘‘facial suture’? of Raymond and (2?) Beecher in Pedewmias and Agnostus. a. Head-shield of Pedewmias transitans (Walcott) after Walcott (Smiths. Mise. Coll., vol. iii, pl. xxxiv, fig. 6). 6. Carapace of Agnostus mnudus (Beyrich) copied from Raymond (Amer. Journ. Sci., 1917, fig. 1). d. Doublure of Pedeumias reflected from underneath the head-shield. s.m. Sutural margin of the doublure. s. Approximate position of the marginal suture (facial suture of Raymond) on ventral surface. e. Hye. c. Cephalon of Agnostus according to authors. p. Cephalon of Agnostus according to Raymond. m.s. Marginal suture (‘‘ ventral facial suture ’’ of Raymond and ?Beecher) of Agnostws. f.c. Wentral free cheeks according to Raymond and (?) Beecher. With regard to the resemblance of the occipital segment to the trunk segments, it may be observed that this is merely an illustration of the principle that in segmented animals specialization of the posterior lags behind that of the anterior segments.. Thus, within the Trilobita the glabellar furrows are obscure or absent most frequently in front, and again, it is this part of the glabella that varies most in shape and dimensions; compare for example, such forms as Conocoryphe, Olenus, Paradoxides, Phacops, Staurocephalus. 1 Bull. U.S. Geol. Sury., No. 30, p. 154, 1886. The Facial Suture of Trilobites. 105 Nevertheless, amid all these changes the occipital, and sometimes the next segment in front of it, retain a close resemblance to a trunk segment. The fixity or non-fixity of the number of cephalic segments cannot be definitely settled until the ventral surfaces of many more trilobites are known. Meanwhile it is significant that in such widely separated genera as Zriarthrus and Marella’ five pairs of cephalic appendages occur and that the last pair in each case resembles those in front more than it does the trunk appendages. The existence of this condition in so primitive a form as Marella suggests that the cephalic segments became marked off as cephalic en bloc, and proves that the posterior limits of the head-shield became defined and the number of its segments fixed at a very early stage in the evolution of the order. In all trilobites, young or old, which possess eye-lines or eye-lobes as well as a clearly segmented glabella, the line or lobe is related to the palpebral segment that is the fifth from the posterior margin. This is another fact which indicates that these five segments are homologous in all typical trilobites, and that no new segment has been added to the cephalon since definitive trilobites came into existence. How many segments lie in front of the palpebral it is quite impossible to say. An additional one is sometimes indicated on the glabella.2 This must be the ocular segment whose pleural portion bears the visual area of the eye upon its hinder margin. ‘The segmentation of the region in front of this is at present merely a matter for conjecture. Tue Position oF THE EYE. The position of the eye seems to be very variable. In the early stages of development of many trilobites it is first seen on the margin. In later stages it shifts on to the dorsal surface, and in the adult it may be quite close to the glabella and to the posterior margin of the cephalon. ‘These facts led Bernard* to regard the eye as a lonely wanderer on the face of the trilobite, and to conclude that it ‘‘had no fixed hereditary locus on the dorsal surface’’. But in other animals an organ that wanders usually takes a train of other organs with it, that is to say it retains its major morphological relationships. Thus the eye of the flat-fish, Plewronectes,* wanders during development from one side of the head over the dorsal surface on towards the other side, but throughout its wandering it is accompanied by its full complement of muscles, nerves, blood-vessel, and bones. That is to say, it retains a definite position in relation to the general morphology of the head. Bernard unconsciously recognizes this fact for the trilobites when he says, ‘‘ The eye never 1. D. Walcott, ‘‘ Middle Cambrian Brachiopoda, etc.’?: Smithsonian Mise. Coll., vol. lvii, pp. 192, 193, 1912. 2 C. D. Walcott, ‘‘ Olenellus, ete.’?: Smiths. Mise. Coll., vol. liii, p. 277, pl. xli, fig. 9, 1910. 31894, p. 420. * Vide F. J. Cole & J. Johnstone, L.M.B.C., Memoirs, No. viii: Plewro- nectes, pp. 174 et seq., 1901. 106 Professor H. H. Swinnerton—._ crosses the cephalic suture.’’?! Had we spirit specimens to dissect we should no doubt find that the trilobite’s eye maintained equally stable relations to the nerves, vessels, and other organs vitally connected with it. The position of the eye, then, is a definite morphological point. When, therefore, every worker from Burmeister to Raymond in describing the trilobite organization states that the facial suture passes behind the visual area and in front of the palpebral lobe, he 1s giving to that part of the facial sutwre a very precise position in the trilobstic anatomy. THe Ecpystat Linz 1n Mrsonactp@. In the Mesonacide there is no fully developed facial suture on the dorsal surface. Rudiments occur occasionally. Nevertheless, these trilobites must have undergone ecdysis. As long ago as 1891 Walcott in describing Callavia Broggeri wrote: ‘‘It is a very common occurrence to find the ‘doublure’ on the reflected under margin lying free from the other parts of the head and with the hypostoma attached. his fact leads to the conclusion that a suture passes around near the frontal margin.”* He mentions that a similar suture is described by Holm in Holmia Ajerulfi. In 1910 the same worker figures an interesting specimen of Pedeumias transitans (see Figure), which further substantiates these observa- tions.* Raymond, referring to this figure, describes the detached portion of the doublure as ‘‘swung back so that it presents its ventral face to the observer on the same block with and still attached to the head-shield”.t This fortunate find makes it possible to determine the morphological relation of this ecdysial line to the dorsal facial suture. Though no true dorsal suture is present the eye-lobes are well shown. If one imagines the doublure replaced in its original position it becomes evident that its line of separation from the remainder of the head-shield must he either marginally or submarginally, and in any case morphologically, far distant throughout its length from the eye. That is to say, no fraction of it passes between the palpebral and ocular segments, and therefore that no fragment of it is homologous with that portion of a typical facial suture which takes this course. To homologize this line with the facial suture and the detached portion with the free cheeks is merely to cause confusion. For the purposes of this paper these may be called the marginal suture and doublure respectively. Tae Ecpystat Linrk 1x AGNOSTIDm. The Agnostide are blind and show no suture dorsally. Beecher believed that they possessed facial sutures and free cheeks on the ventral side.2 Raymond claims to have found these in Agnostus nudus® (see Figure). Before applying the results of the above 1 1894, pl. 420. 2 C. D. Walcott, Tenth Ann. Rep. U.S. Geol. Surv., 1891, p. 638. 3 1910, pl. xxxiv, fig. 6. 4p. kh. Raymond, Amer. Journ. Sci., vol. xliii, p. 208, 1917. > Amer. Journ. Sci., 1897, p. 183. $ Tbid., 1917, p. 198. The Facial Suture of Trilobites. 107 discussion to this case it should be noted that the region which he calls the cephalon in this species has hitherto been unanimously regarded as the pygidium. The only reason he advances for disagreeing so utterly with previous workers is that he has discovered structures like free cheeks on the ventral side of the ‘‘ pvgidium”’. Until he brings forward independent evidence to prove that the pygidium is not a pygidium, or that the ventral structures are free cheeks, his discovery cannot be regarded as valid. Meanwhile, all independent evidence seems to be against him, and his discovery seems to prove only that Agnostus underwent ecdysis by way of the pygidium. It is of course possible that Raymond may yet prove his case. When he does that his further deduction! will be valid, viz., that the suture and ventral linear ‘‘free cheeks” he has found in Agnostus are “‘analogous”’ with the marginal suture and detachable doublure of Pedeumias. But this can only prove that they cannot be homologous with the dorsal facial suture and dorsal free cheeks of other trilobites. The fact that the closely allied but distinctly more primitive genus Pagetia* has both eyes and true facial sutures indicates that Agnostide have lost both these features, and have reverted secondarily to a marginal ecdysial line. This point of view receives support, on the one hand, from a consideration of the extraordinary degree of specialization attained by the Agnostide in all respects, and on the other hand from the existence of indications of eyes and true facial sutures in the allied but much more primitive genus Mollisonia.* Tue Eopysran Line In THE TRINUCLEIDE. The problem of the facial suture in Zrinucleus has been very fully discussed by Reed,* who concludes that the true facial suture has disappeared, that the free cheeks have fused with the fixed cheeks, and that the suture which is present along the margin has come into being secondarily. Raymond disagrees entirely with these con- clusions, and regards the marginal suture and ventral free plates of Trinucleus as facial suture and free cheeks respectively. He rightly homologizes these features with those which he claims to have discovered in Aynostus® and, by implication, with the suture and free doublure of Pedewmias. In other words Trinucleus has nothing which is homologous with the true facial sutures and free cheeks, and Reed’s conclusions are proved to be correct by Raymond’s own evidence. Moreover, though Reed finds no satisfactory traces of dorsal facial sutures, he does find eye-lines and vestiges of eyes. When these occur they do not show that association with the marginal suture which would prove this to be a true facial suture. Orometopus, if it be related to the ancestral stock of Zrinucleus, 1 Thid., p. 208. 2 C. D. Walcott, Smiths. Misc. Coll., vol. lxiv, No. 5, p. 407, 1916. ? Smiths. Misc. Coll., vol. lvii, p. 195, 1912. 4 GEOL. MaG., 1916, p. 175. ° 1917, pp. 201 et seq. 8 p. 203. 108 Professor H. H. Swinnerton— supplies proof positive that Reed is right. Raymond,! however, denies the relationship because Orometopus has compound eyes, large free cheeks on the dorsal side, less specialized glabella, more than six free thoracic segments, and a square hypostome. ‘he first two differences, being the subjects of dispute, may be left out of account. The remaining differences are not differential characters, but are such as are usually looked for between the earlier and later members of a genetically related series. The type of argument he thus applies to Orometopus would prove that Meritherium had no relation- ship to Hlephas, or Hyracotherium to Equus. Incorrecr Usace or Eupryonocican EVvIpENCcE. Agnostus and Trinueleus are the typical representatives of Beecher’s Hypoparia, which was founded upon inferences drawn from the study of the development of many trilobites. In this it was observed* that the eye appeared most frequently upon the margin, and travelled backwards bringing the facial sutures and free cheeks with them as development advanced. The occurrence of this phenomenon in so many trilobites was taken to indicate that the ancestors had marginal eyes, marginal or sub-marginal facial sutures, and ventral free cheeks. In coming to this conclusion sufficient care was not taken to test. the value of the developmental evidence by a comparative study of the adult structure. The larve to which Beecher attached most importance have, in addition to the marginal position of the eyes, a glabella which increases in calibre anteriorly and often extends to or even beyond the front margin of the head-shield. Compare this condition with that found in such primitive adult trilobites as Conocoryphe, Ptychoparia, etc., which were known to Beecher, and Nevadia*® and Nathorstia,s which have been discovered since he finished his work. In these adults the eyes when present are dorsal in position, the glabella diminishes anteriorly, and does not approach the frontal margin. When the facts of embryology clash thus with those of comparative anatomy the former must be interpreted with extreme caution. — The conditions prevailing in less primitive trilobites throws a flood of light upon the conditions in these larve. Thus an increase in the width of the anterior segments of the glabella is frequently exhibited by the more advanced members of a progressive series, ef. Olenellus with Mevadia. It can only be concluded that the larvee which exhibit this feature are specialized also, at least, in this respect. Again, in such a series as Cheirurus, Spherexochus, and Deiphon the forward extension and inflation of the glabella are accompanied by an assumption of other features, such as the marginal position of the eyes and curious isolation of the pleure, which according to Dollo point to a planktonic mode of life. The peculiarities of the glabella and the position of the eyes in the 1p. 208. 2 Amer. Journ. Sci., 1897, p. 184. °C. D. Walcott, Smiths. Mise. Coll., vol. liii, p. 256. 4 Thid., vol. lvii, p. 194. The Facial Suture of Trilobites. 109 protaspis of certain trilobites are therefore not to be regarded as ancestral features, but, more probably, as adaptive characters associated with a planktonic habit.’ If this be the true interpretation of the facts, then the backward shifting of the eye during development has no phyletic significance, but is merely associated with the cessation of the larval planktonic mode of life and the assumption of the benthic habits of the adult. Beecher was unfortunate in his choice of developmental evidence upon which to base his opinions. Had he given more attention to the larve of the Mesonacide he would never have instituted the division Hypoparia. These larve retain traces of several pleure in the cheek region, and thereby show themselves to be the most primitive of all known trilobite larvee and therefore the most valuable indicators of ancestral. conditions. But even in the youngest of these larve known the eyes are dorsal and the facial suture is absent. This agrees with the evidence of the comparative study of the adult and therefore outweighs the perhaps more abundant evidence from more specialized larve. Raymond falls into the same error*as his great teacher when he hints at the resemblance between the young of Zrimucleus and the adult of Agnostus as evidence of affinity. A trilobite with such forms as Harpes and Dionide closely allied to it could not possibly have descended from an Agnostus-like ancestor. THe Tritopita Ark MonopHy etic. Raymond finds difficulty in accepting my interpretation’ of Mesonacid structure and development because it implies that ‘‘ the anterior segment was not oculiferous’’ ‘ in them as in other trilobites, and that therefore trilobites must be polyphyletic. Why he should consider it necessary that the oculiferous segment must be the anterior one he does not state, but as long as there are to be found annelids such as Avrudo having eyes on every segment as far back as the fifth there is no need to postulate the first segment as the only one that can be oculiferous in trilobites. It has been shown above that the ocular segment is the sixth from the posterior margin in all trilobites which exhibit sufficiently abundant traces of segmentation to enable an opinion to be formed. Whether this is the anterior segment or not does not matter; the essential point is that the segment which bears the eye is the same for all trilobites, so that from this standpoint the order is monophyletic. ConcLusion. The trilobites are a compact group, the members of which at first underwent ecdysis along a line which may be called the marginal suture. ‘To facilitate the removal of the covering of the eye in moulting”® dorsal facial sutures appeared independently in several distinct lines of descent. It is necessary to emphasize the fact that taken as a whole the true facial suture is composite, L. Dollo, La Paléontologie ethnologique, Bruxelles, 1910, pp. 406 et seq. 2 p. 204. * GEOL. MAG., 1915, p. 492. * Amer. Journ. Sci., 1917, p. 208. > Tbid. 110. Dr. F. A. Bather—Notes on Yunnan Cystidea. being made up of a new dorsal portion intimately associated with the eye, and an anterior portion which is probably a section of the marginal suture. The posterior section of the latter seems to have been completely replaced functionally by the newly instituted line running behind the visual area. The whole of the marginal suture was liable to be resuscitated in forms which, like Zrinucleus, became blind secondarily and thus had no special use for a dorsal suture. The position of the marginal suture, whether primarily or secondarily instituted, lay somewhere in the vicinity of the margin of the cephalon. For the present it may be left as an unsettled point whether the suture seen near the margin in such blind forms as Conocoryphe and Ampyz is a true facial suture or a marginal one. The line of reasoning followed above points to the latter as the correct interpretation. The theoretic implications of the name Hypoparia render it unsuitable for describing those forms in which a dorsal suture has not yet appeared, and in which the marginal suture is of primary origin; hence the introduction of the name Protoparia for these. The Protoparta cannot include Trinucleus, for that is a highly specialized, not degenerate Opisthoparian, neither can it include Agnostus, for that is an even more highly specialized Proparian. This being the case Raymond’s suggestion that the terms Hypoparia and Protoparia are practically synonymous cannot be accepted. III.—Norrs on Yunnan Cystipga. III. Szvocysrrs coMPARED WITH SIMILAR GENERA. By F. A. BATHER, D.Sc., F.B.S. . (Published by permission of the Trustees of the British Museum.) (PLATE III.) B.—Comparison wire Iaeacysris (continued). 3. Structure of the Pores in Megacystis. SSENTIALLY the pores of Megacystis are diplopores, for they are arranged in pairs. This is evident on the inner surface of a plate (E 16169, EK 7671). Here each pore-pair lies in a shallow depression, and each pore again lies in a slight depression at the bottom of this (fig. 14). Compare Sinocystis yunnanensis (antea, . 038). : no these inner openings the pore-canals pass outwards through the meso-stereom, still retaining their paired character. This can be traced in vertical sections, since the canals as a rule follow a fairly straight course normal to the surfaces; but it is more easily seen in horizontal sections of a plate (KE 7675), or in the naturally worn surfaces. For instance, E 16169 shows the @-channels in only a small region, while the remaining surface is worn, with the result that the structures manifest all over the theca appear to be ordinary diplopores. This effect is particularly obvious when the pore-canals - have been filled with a dark matrix (e.g. E7644, E 7641). Some- times the matrix has been dissolved out, leaving the canals empty (E 16171). | 1 1916, p. 209. Dr. F. A. Bather—WNotes on Yunnan Cystidea. 111 An outer surface that has been slightly worn, so as to uncover the w-channels without obscuring them, shows the outer openings of the pore-canals connected by shallow channels on the following plan (fig. 15). The simplest arrangement consists of two channels, curved like the sides of an O, with a pore at each end. Next comes a doubling of these channels. Both of these arrangements are well shown near the base of E 7676 (fig. 16). It appears as though the doubling were due to, first, a broadening of each channel, and, secondly, a median up-growth of its floor. This process may take place on one side only, so as to yield a total of three channels; or it may be repeated on one side, yielding five channels (fig. 15), or, very rarely, on both sides, yielding six. It is, however, unusual to find quite so simple a pattern: modifica- tions arise in two ways. First, by simple irregularity in the curves of one or more channels. Secondly, by other up-growths of the floor so as to bar one or more channels (fig. 17). Each of these modifica- tions seems to be subject to a special limitation. The irregularity is subject to the bounds which are set to the channel-system of a single pore-pair. The barring is subject, apparently, to the condition that such a channel-system must be continuous; thus, no part of a channel has been observed with a bar at each end; however irregular the labyrinth may become, it is always possible to track along every part of it. Now as to the bounds of a channel-system. In no case does a system transgress the boundary of a plate; no pore-canal, and no channel, ever crosses a suture. Within each plate the diplopores are distributed over the whole surface—not regularly or according to any pattern, but at approximately equal distances. ‘There are two plans of structure: the diffuse (figs. 16, 17, 18) and the concentrated (figs. 19, 20, 21). In the former the channel-system is diffuse and is separated from adjoining systems by a tract no wider than a single channel or, what comesto the same thing, no wider than a ridge between two channels. No wider is the space left at the sutural margin. Each channel-system spreads itself out until brought up against its neighbours; and, since the foci of each system are distributed irregularly, the boundaries also become irregular ; did the systems start from equally-distributed centres, their boundaries would form regular hexagons, but, as it is, they form irregular polygons. It is therefore not easy to distinguish these boundaries from the other ridges, and so the whole thecal surface appears at first sight covered with a confused maze of channels. It seems possible that this complexity has misled even so acute an observer as Professor Jaekel (1899). His plate iv, fig. 2a shows in some cases as many as 5, 6, or 7 pores belonging to the same channel- system. There may in rare cases be more than one pore-pair to a system, but I am not convinced even of that. What does often happen is that the outer opening of one (or both) of the pores is erossed by a bar (fig. 17), so that externally the pore seems duplicated or even triplicated. There is also a deceptive appearance of pores at other bars. Finally, the pores and their connecting channels are covered on the 112. Dr. F. A. Bather—WNotes on Yunnan Cystidea. outer surface by a thin epistereom, so that on a well-preserved surface they are at first invisible, and all that one sees is the finely-vermicular ornament of the epistereom (EK 7633). If, however, the surface be wetted, it is usually possible to see the channels beneath, looking much like the tunnels that a boring sponge or alga makes between the layers of a mollusc shell (fig. 18). The manifestation of the buried channels is generally increased by the fact that they are injected with a fine mud, which has reached them through the pore- canals from the interior of the test. It does not seem possible to explain the appearances as due to anything other than a complete coating of stereom. In thecas with diffuse channel-systems, the outer surface, when well-preserved, is equable and smooth, except for the fine ornament. In thecas with concentrated channel-systems, the outer surface is raised into a little pustule over each system (E 7629, E. 7672, EK. 7673, see fig. 19). When slightly worn, the ends of the channels are opened up and look like so many pores on the surface of the pustule (fig. 20). Further wearing shows that in every case there is only one diplopore to each pustule (fig. 21). Thus, Miller writes of H. ornatus (1878, p. 182): ‘‘ Surface . . . pustulose.. . The pores open upon the summit of the granules, and where the granules are worn off, the plates show the pores, in pairs, passing through to the interior.” So also of H. splendens, Miller & Gurley write (1894, p.7): ‘‘The whole body is pustulose and every pustule is pierced by a pair of pores.” These pustules with their appearance of many pores may be compared with those vesicular multiperforate tubercles in Caryo- crinus, of which so admirable an account was given by James Hall (1852, Paleont. N.Y., vol. 2, p. 220). There a single pepper-box pustule, as one may term it, may have as many as six outer openings, but only one pore-canal leads to the inner surface of the thecal plate. In older specimens the pustules of a single row enlarge till they coalesce, ‘‘ forming a vesicular ridge.”’ The various modes of preservation and the differing amount of weathering produce a number of diverse appearances in these two plans of structure. Besides those already alluded to, one notes that in the diffuse pattern weathering frequently affects the area of the channel-system more than its boundary, so that the latter stands up as a ridge; possibly it is actually of denser stereom than the channelled area. On the other hand, the injected material may be more resistant than the stereom, and in this case the channels, and especially the pore-canals, stand out while the surrounding tract is weathered away. In some cases this eventually produces an irregular pustulation (E 7630), which must not be confused with the true surface-pustulation of the concentrated plan. It is plain that the thecas were often lying for some time on the sea-floor, and that their surface was then worn and overgrown in part by bryozoans and other incrusting organisms. When fossilization took place the open channels formed a key for the matrix, which ultimately became firmly bound to them by secondary calcification. In such cases the pattern shows up in sinuous ridges of pale Dr. F. A. Bather—Notes on Yunnan Cystidea, 1138 light-reflecting matrix on the darker light-absorbing stereom, and it is hard to believe that these ridges really represent channels once covered by epistereom. Even when one’s mind is clear as to the facts, it is not easy to understand the origin of the channel-systems. There are two features to be explained : first, the number and sinuous extension of the channels; secondly, their closure by epistereom. The simplest pattern, as Professor Jaekel points out (1899, p. 418), seems but a modification of a single oval peripore’ (Hofchen) ; when the outer covering is worn away, there is indeed little difference apparent. The channels connecting the two pores correspond to the moat of the peripore (fig. 16). How or why did they become covered? The answer to that question might also furnish the clue to their multiplication. ‘lo one who, like Prof. Jaekel, believes that the normal diplopore was covered (antea, p. 518), there should be no particular difficulty. Now the diplopore is obviously a complete unit. If it had a roof of epistereom, the development of a channel- system would take place by the union of the periporal floor with the roof—first between the two pores, leaving a channel on each side; then along the floor of each channel, thus splitting it into two; and soon. Itis assumed by this hypothesis that the channels as they multiplied would move apart, at all events in the case of the diffuse pattern. This explanation is beautifully simple, but it provides no motive force. A diplopore seems so finished a structure, so obviously adapted to some function or other, that one cannot imagine why in this limited genus it should become broken up in this way. Let us now suppose that the diplopore was not originally roofed over. The natural interpretation then seems to be that the pore- canals served to bring fluid (probably ccelomic) into osmotic connection with the surrounding medium, and that the fluid passed out by one canal and in by the other. The combined tube probably extended as a papula, and for the base of the papula the peripore afforded an attachment suggestive of retractile muscles. We have seen in Sznocystis how the central region of a diplopore is raised into a pustule, attaining sometimes considerable height. This implies deposition of stereom in the walls of the papular tube. Excess of deposition would interfere with the assumed function of the papula, and might lead to the closure of the pores, as Dr. Reed believes to have been the case. ‘This calcification of the wall, with consequent reduction of the osmosis, would have to be counteracted, and that can be effected only by increasing the surface. Here then is the motive for the multiplication and extension of the channels. In the case of pustule-formation, the channels seem to have remained close round the original pustule, producing the concentrated plan. The diffuse plan can not have been preceded by pustule-formation, and we must suppose the calcification to have taken place round the margin of the peripore more rapidly than in its central area. 1 The term ‘‘ peripodium ’’ was extended to these structures by Lovén (1883, Pourtalesia, p. 57), since he believed that tube-feet sprung from them as from the similar structures in Echinoidea. It seerfs advisable to drop this use of the term, along with the belief that it implies. DECADE VI.—VOL. VI.—NO. III. 8 114 Dr. F. A. Bather—Notes on Yunnan Cystidea. There is yet a third hypothesis. By placing his Zrematocystis with Aristocystis in a family Aristocystide, Dr. Jaekel implies that the channel-systems were derived from the irregular groves of the latter genus. He says in effect :—In this family of Diploporita the peripores are lengthened in worm-fashion and form closed respiratory spaces beneath the epistereom. In Aristocystis the epistereom shows a smooth surface, and the pores are not visible till this is removed. They are then seen to be connected by irregular channels—the elongate peripores—and each channel may include two or more pores. One of Jaekel’s drawings (p. 409) shows as many as four pores, three at the ends of a Y and one at the fork. One of Barrande’s figures (1887, pl. 38, fig. 23) shows six pores in a channel. In Zrematocystis, Jackel continues, this tubular elongation of the peripores led to their duplication and combination, while the mesostereom also shared in their envelopment. It is not quite easy to follow this account. In the first place there is still room for scepticism concerning the covering of epistereom. The outer layer seen in many of these Bohemian fossils has not yet manifested any structure, and may be nothing more than an adherent film of limonite induced by the decay of the organic stroma. Secondly, the account implies that the channel-systems of Trematocystis, or at any rate the more complicated ones, involve more than two pores; as already stated, I am unable to confirm this. Thirdly, the interposition of the peculiarly irregular stage repre- sented by Aristocystis bohemicus between the normal diplopore and the simplest system seen in Zrematocystis raises a gratuitous difficulty, and one apparently inconsistent with Jaekel’s own comparison of the two latter. Possibly Jaekel had in mind (though he did not mention them) the channel-systems of Mippocystis (antea, p. 72). There is an obvious resemblance between an omega and two horseshoes set side by side with the adjacent ends meeting in a single pore. But closer scrutiny of the facts renders it doubtful whether a system of this pattern is ever found in either Megacystis or Hippocystis: in the former, if the pattern resembles an omega, it is with a difference, and there are two pores to the system, not three; in the latter the horseshoes neither meet nor overlap, so far as one can judge from Barrande’s figures and description. It is therefore no easier to derive the Degacystis system from that of Hippocystis than from any simple diplopore. On the whole the second of the three hypotheses here discussed seems best to harmonize the various views that have been expressed as well as the greater number of the structural facts. The idea that the assumed papule tend to be calcified is confirmed by the lofty pore-pustules of Sznocystis Jloczyi and the pore - turrets of S. yunnanensis. The supposed clogging by excess of calcification is confirmed by the pepper-box pustules of Caryocrinus ornatus. Two large tubercles of similar nature appear, as a result of individual and local hypertrophy, in the holotype of Megacystis hammelli (Miller, sub LHolocystites). Whether the elongation and sinuosity of the peripores in Aristocystis was due to a similar need for extending the respiratory surface, cannot be decided. At any rate the channel- Geox. Maa., 1919. Prare III. F.A.B. del. Bale & Danielsson. PORES AND CHANNEL-SYSTEMS IN MEGACYSTIS. 16, 17, 18, Diffuse plan. 19, 20, 21, Concentrated plan. All figures enlarged 20 diameters. L. F. Spath—Notes on Ammonites. 115 systems of Megacystis, each with its single diplopore, do not seem like direct modifications of the Aristocystis plan. It is curious that this type of channel-system should, to all appearance, have been confined to a single arm of a single sea during one relatively brief period of the earth’s history. EXPLANATION OF PLATE III. PORES AND CHANNEL-SYSTEMS IN MEGACYSTIS. Fic. 14.—Openings of two diplopores on the inside of the theca in EK 7671. 15.—Three diagrams to show the multiplication of the channels from (a) the primitive two, through (6) four, to (c) five. ,, 16.—Simple channel-systems, corresponding to stages a and 0 of Fig, 15, seen in K 7676. ,, 17.—A portion of the worn thecal surface in H 7639, showing more com- plicated channel-systems. In a the two pores are distinct, but there is a deceptive appearance of a pore where the short channel ends on a bar. In 0 the pore to the right is divided by a bar. In ¢ both pores are so divided. ,, 18.—A portion of the unworn thecal surface of E 7633. Two channel- systems are faintly seen beneath the epistereom. ,, 19.—A portion of the unworn thecal surface of E 7673, showing pustules. Here conditions of petrifaction are such that the underlying channels can nowhere be detected. ,, 20.—Pustules in various stages of weathering; from the deceptive appearance of many pores, through the exposure of the channel- system, to the beginning of its disappearance. Selected from EK 7629. », 21.—Other stages in the wearing down of the pustules till the primitive diplopore is exposed. Selected from a single plate in the theca of E 7672. The figure-numbers continue those of the text (Nov. and Dec., 1918). All figures enlarged 20 diameters. 2? IV.—Norrs on AMMONITES. By L. F. Spatu, B.Sc., F.G.S. JU M N addition to the variability of the suture-line in a given species, mentioned previously, asymmetry of the elements on opposite sides of the same suture-line is very frequent and probably universal in so far as the minor frillings are concerned, which is only to be expected in organic beings. This phenomenon has lately been illustrated again in Zioceras by Horn,! and in Dactylioceras by Swinnerton & Trueman.? The latter authors also have some interesting observations on asymmetry associated with lateral displacement of the siphuncle which is of sporadical occurrence in Ammonites. Canavari* had noticed that in some Spezia forms the siphuncle was asymmetrical in the young. and then became central; and Solger* records a familiar excentricity in Hoplitoides. The 1 “Die Harpoceraten der Murchison#-Schichten d. Donau-Rhein Zuges ”’ : Mitt. Grossherz. Bad. Geol. Land. Anst., vol. vi, pt. i, p. 264. 2 Op. cit., Q.J.G.S., vol. Ixxiii, pt. i, pp. 40, 51, 1917. 3 ‘* Beitr. z. Fauna d. Unt. Lias v. Spezia’’: Paleontographica, vol. xxix, pt. ili, p. 192, 1882. 4 ** Fossil d. Mungo-Kreide ’’: Geol. vy. Kamerun, ii, p. 217, 1904. 116 L. F. Spath—Notes on Ammonites. asymmetry here is lost when the venter becomes acute. On the other hand, when dissecting a specimen of, e.g., Pstloceras erugatum (Bean-Phillips) with asymmetrical suture-line it is found that on the innermost whorls the suture-line is quite normal and that the position of the siphuncle (and of the ventral lobe) shifted gradually away from the median plane, thus causing unequal development of the opposing halves of the suture-line. Swinnerton & Trueman remark that usually only the ventral features are affected, and enumerate many genera in which this sporadical displacement has been noticed. These authors also point out that nearly every specimen in which this type of asymmetry has been noticed has a rounded or flat venter. The most notable example of the round-ventered shells is Ps¢loceras, several signs of instability in which have already been noticed. On a previous occasion! the writer attempted to demonstrate the Monophyllites-Mojsvarites ancestry of this genus, and in this original stock asymmetry apparently is unknown. In the Yorkshire repre- sentative Pseloceras erugatum, a particularly variable species-group, asymmetry may be associated with close or distant septation, or may be absent altogether. Again, there may be approximation of the last two to six septa or no approximation at all, with or without “reduction”. The specimens are also generally smaller than the Somerset equivalent P. planorbis (Sowerby), which unfortunately is — always squashed, or the Wurtemberg P. pszlonotum (Quenstedt), and — the Yorkshire examples remind one of the dwarf-forms of the Hierlatz, so that one might be tempted to compare them with organisms living under unfavourable conditions, such as the shells in the brackish waters of the Baltic. But the enormous development ot the genus Pszloceras in the Alpine Hettangian, where asymmetry is very common, shows that it was a dominant and thriving stock. It may be assumed that there was a great ‘‘ burst’ when, with the extension of the sea over wide new areas, the Ammonites which in the Rheetic had nearly become extinct, were able to spread again. The one surviving family Phylloceratide, reduced to a few secluded localities of the Alpine Rheetic Sea, entered upon a new phase of development, and in its principal first Liassic descendant Pszloceras showed a strong adaptive radiation. It might be asked whether this could not have affected the position of the siphuncle, and therefore the suture-line, in an attempt to ' change a bilaterally symmetrical swimmer into a crawling benthonic organism. For, as has already been pointed out, its probably nectonic contemporary Phylloceras (which, like the somewhat later ‘* Rhacophyllites”’, Huphyllites, Parapsiloceras, Pleuracanthites, and Analytoceras, never migrated beyond the Alpine Hettangian Sea) does not show these signs of instability.2, Diener, who thinks the 'L. F. Spath, ‘‘On the Development of Tragophylloceras Loscombi’’ : Q.J.G.S., vol. lxx, p. 352, 1914. 2 Canavari (op. cit., 1882, p. 69) has thought that asymmetry of the suture-line was not found in Phylloceratide, but he figures as Amaltheus (Sphenodiscus) sinister (ibid., pl. ii, xvi, fig. 17a—c) a form of ‘‘ Rhacophyllites’’, that clearly shows this asymmetry; and both Pompeckj, and Swinnerton and Trueman mention it as occurring in Tragophylloceras, but these are not typical L. F. Spath—Notes on Ammonites. ly) asymmetry of no biological importance, would look upon such forms as “ Psiloceras”’ abnorme (Hauer), ‘‘ Pstloceras’’ Suessc (Hauer), and Oxynoticeras Janus (Hauer), as small forms, with limited geographical distribution, and probably adapted to a crawling mode of life.1 The first two, in which apparently the asymmetry is fairly constant, are comparable to Psiloceras, with which genus, however, they cannot be united. The last, where the ornament also is affected, has a counterpart in Amaltheus paradoxus (Stahl), though here the suture-line may also be normal, and it seems that Diener’s suggestion of a crawling mode of life may hold good for these abnormal forms. In helicoid shells that must be explained in this manner, the position of the siphuncle apparently is not affected, however. In a round-ventered shell the position of the siphuncle in the median plane is, of course, not essential; and the functions of the indented septal edge, both as a strengthening feature and as a means of attachment of the animal to its shell, would not be interfered with by an unsymmetrical arrangement. It may be assumed that Psiloceras, though a dominant and thriving genus, was comparatively unstable owing to the instability of its conditions of existence. Neumayr’ drew attention to this instability, and pointed out the variability of the Alpine P. (calliphyllum species-group) forty years ago, and Rothpletz* shows that even in a locality where there is a continuous transition from the Rheetic Keessen beds with Moysvarites planorbodes to the variegated limestone facies of the planorbis-zone (Marmorgraben, near Mittenwald, Bavarian Alps), only brachiopods and lamellibranchs are found in the first six to twelve feet of Lower Liassic marls. Asymmetry of the suture-line in Psiloceras may then be looked upon as an abnormality that had attained a considerable degree of constancy, but which was due to constitutional instability. This was eliminated when an exceedingly strong radiation with production of keeled and grooved forms (both keel and groove being in part protection of the siphuncle) took place. In the case of flat-ventered shells, such as Hoplites splendens, Swinnerton & Trueman think that ‘‘ asymmetry is probably a growth- phenomenon associated with the tendency of the siphuncle to take up Phylloceratids. Itmay be suggested for e.g. Meneghiniceras and other ‘‘ Rhaco- phyllites ’’, that, like many modern marine organisms, they were pelagic in the young and littoral when adult. The form figured by Canavari affords a good illustration of the unsatisfactory results of a morphological classification of Ammonites according to the adult suture-line. Canavari wrote: ‘‘ A remarkable circumstance in this species is the presence of three lateral lobes. Thus it lets itself be grouped in section B of the Amaltheids, according to Neumayr & Uhlig, which comprises the forms with three or more lateral lobes, and perhaps in the sub-genus Sphenodiscus, Meek, with complicated lobes.’’ In1888, Canavari (‘‘ Contribuzione alla Fauna del Lias inferiore di Spezia’’: Mem. R. Com. Geol. Ital., vol. iii, pt. ii, p. 34) assigned this form to the genus Oxynoticeras, but its suture-line shows it to be a Rhacophyllitid. 1 Op. cit., 1912, p. 81. 2 “Zur Kenntnis d. Fauna d. Unterst. Lias i. d. Nordalpen’?’: Abh. k.k. Geo]. Reichsanst., vol. vii, pt. v, p. 25. 3 ‘‘Das Karwendelgebirge’’: Zeitschr. d. D. O. Alpenvereins, vol. xix, pp. 427-8, 1888. 118 L. F. Spath—Notes on Ammonites. a stable position along the angle bounding the venter’’.! Among Pseudoceratites, e.g., Protengonoceras and Heterotissotia belong to this group, and Hoplitovdes in the young stage, though here the develop- ment of an acute venter in the adult causes the disappearance of the excentricity of the siphuncle. Solger saw an adaptation to a benthonic existence in the latter, but the great variability shown in the thirty-five specimens of Hoplitoides, quoted by Solger, points to unstable conditions. This author also adduces the reduction of the suture-line, the local restriction of the genus Hoplitoides, his discovery of a specimen with several destroyed air-chambers, and the similarity to the Triassic Ceratites, as evidence for the adaptation to a benthonic existence. The writer has already given his opinion on the first and third points, and the second does not now apply since Hoplitoides has been found, e.g. in Tunis (Pervinquiére). With regard to the likeness of the Pseudoceratites of the Cretaceous to the real Ceratites of the Trias, Phillipi’s conclusions on which Solger’s theory of adaptation to a benthonic mode of iife for both was based, have also been disproved (Diener). Asymmetry in oxynote shells is very rare, and Swinnerton and Trueman mention that they have not detected one case of asymmetry in specimens with keeled venters (p. 54). The most notable example is Garmeria heteropleura. Neumayr & Uhlig? examined about fifty specimens of this and found the siphuncle excentric in each. It may be assumed that the function of an oxynote venter was, primarily, to assist rapid motion through the water, and only secondarily to act as protection for the siphuncle, which in an unstable stock might vary its position slightly, especially if the keel be hollow. Though this last: case is doubtful, however, the writer is inclined to think that asymmetry of the siphuncle and suture-line cannot, by itself, be taken as sound evidence in favour of adaptation to a benthonic, crawling existence. In connexion with a pathological or accidental case of asymmetry in a Perisphinctoid form, where the dorsal as well as the ventral features of the suture-line are affected, Swinnerton & Trueman refer again to the gas-pressure which, in Ammonites, was assumed to have been strong enough to impose upon the septum a marked convexity. They state (p. 52): “If this [septum-secreting area of the mantle | became hypertrophied on one side, it would still assume the form of a stretched membrane, but being more resistant to pressure from behind, would not become so concave forwards as the other half.” And on p. 37 the authors suggest that the second septum of Dactylio- ceras already must have been formed under the influence of that pressure, though at the time of formation of the protoconch and even of the first septum, the mantle was strongly convex. Brief allusion to this pressure has already been made in connexion with the phylogenetic ‘reduction’ of the suture-line; but in Pseudoceratites, where the simplification is said to have been carried to such extremes, the septum is still convex forwards. It seems to * Op. cit., p. 55. 2 “Uber Ammon. a. d. Hilsbild. Nordd.”’: Paleontographica, vol. xxvii, pp. 135-6, 1880-1. L. F. Spath—WNotes on Ammonites. 119 the writer that the internal pressure of air, gas, or aerated fluid in Ammonoids need not have differed from that in Nautiloids of a corresponding type of shell and mode of existence, that it depended on the depth at which the septum was formed, i.e. external pressure, and that the differences in the position of the siphuncle, in the thickness of the shells, and in the methods of attachment, determine the shape of the septum. Mr. Crick* has shown that ‘‘not only was the Ammonoid animal, like the WVautilus, at least at some periods, attached to its shell by means of the lobes and saddles of the posterior portion of the body—corresponding to those of the edge of the septum of its shell—but it seems . . . that it was further provided with an annulus in addition to shell-muscles, as in the recent Nautilus. It would appear, therefore, as if the provision of an annulus were an absolute necessity to the animal in addition to the shell-muscles, and most probably Dr. Waagen’s explanation of its occurrence is the correct one, viz. that the annulus and shell-muscles served not merely to hold the animal to its shell, but formed also an air-tight band around it, fastening the mantle to the shell.’”’ Since the muscles could probably easily become detached, as in Nautilus, it may be assumed that the protrusions of the mantle that went into the lobes tended to strengthen their adherence to the septum by progressive backward penetration of their fibres, thus causing the convexity of the septum. In acylindrical shell like Lytoceras, where the elements radiate from the centre of the septum, the lobes would attach themselves more or less equally all round the shell-wall, and the more complex the septal edge the firmer the attachment. Such progressive complication is shown, e.g. in the first lateral lobe of the Androgynoceras Henleyi—Becher-nautilifornus series, and on the other hand it has already been suggested that, on the adaptation to a benthonic existence in such forms as Cochloceras or Rhabdoceras, extreme simplification of the suture-line may result; for in these the need for firm attachment of the animal to its shell, while muscles and annulus shifted forward after completion of a new septum, was probably less great than in an active swimmer. It has already been mentioned that ‘‘the tortuous windings of the foliated margin of the transverse partitions . . . strengthened the shell of Ammonites’’.?, Buckland* examined at great length the ‘“proofs of contrivance and design’’. Apart fromthe “use of giving 1 “*On the Muscular Attachment of the Animal to its Shell in some Foss. Ceph. (Ammonoidea) ’’: Trans. Linn. Soc., vol. vii, pt. iv, p. 109, 1898. 2 R. Owen, Lectwres on the Compar. Anat. and Physiol. of the Invertebr. Anim., 1843, p. 331. ° ** Geology and Mineralogy, etc.’’?: Bridgwater Treatise VI, vol.i, sect. iii, “Nautilus,’’? pp. 310-32; sect. iv, ‘“ Ammonites,’’ pp. 333-57; also sects. v and vi, pp. 357-60; and vol. ii, pp. 58, 59, 62. This author (p. 62, vol. ii) also stated that the “‘course of the transverse plates was beneath the depressed and weakest part of the external shell, avoiding the bosses . . . which from their form were strong’’. This is not borne out by the specimen of Hoplites awritus, figured by Swinnerton and Trueman (op. cit., pl. iv, fig. 8), and it seems that in general the septal edge is independent of the position of the tubercles, which are also often irregularly spaced. 120 L. F. Spath—Notes on Ammonites. strength to the shell to resist the pressure”, the ‘‘ further use suggested by von Buch of affording points of attachment to the manutle’’, showed to him “the union of two beneficial results from one and the same mechanical expedient’”’. Zittel’ and Uhlig? held that the strongly ramified borders of the septa serve to increase the solidity of the shells, and the latter author showed (for Lytoceras) that ‘‘as the whorls only just touch one another they could offer little mutual support, and therefore every increase of resistance, if only slight, must have been of great value. Thus, physiologically, the sutural lobes would have served the same purpose that was attained in another genus with very evolute whorls, “Beitr. z. Geol. v. Niederland. Indien’’: I, 4, Palseont. Suppl. IV, 1912, p. 173. ® Whether the earliest representatives were active benthonic animals or attached and sedentary, is not known. But it is probable that from the ancestral capulicone, cyrtocones and orthocones arose, with elongation of the shell after the manner of tubular structures in Actinozoa, Polyzoa, Annelida, and Gastropoda ( ‘‘Guide to the Fossil Invertebrata Animals in the Department of Geol. and Pal. in the Brit. Mus. (Nat. Hist.),’? 1907, p. 147), and the formation of septa at the end of the cone only after a continued period of elongation and pulling away of the visceral hump from the cone, probably to give it buoyancy. But orthocones and cyrtocones cannot have been active swimmers. (See the interesting paper by O. Jaekel, “‘ Thesen iib. d. Organis. u. Lebensweise ausgestorbener Cephalopoden’’: Z.d.g.G., vol. liv, p. 67, L. F. Spath—Notes on Ammonites. 121 of which the Ammonite septum was composed was probably of the same character and the same strength per unit cross-section as it is in the living Vautilus, and similarly deposited on a conchiolin membrane, starting in the region away from the siphuncle. Pfaff! found that in many well-preserved Gault Ammonites the pearly substance was quite similar and showed an identical structure of more or less parallel thin lamelle, as in the septum of Nautilus pompilius. This author also shows in detail how in the case of Nautilus where the septa are concave forwards, as well as in Ammonites, external excess pressure would be transferred to the shell wall; and he comes to the conclusion that the arched septum of Ammonites need be only one-sixth of the thickness of the septum of Nautilus. But Pfaff? further assumes that one reason why the suture-line of JV. pompilius is only curved as compared with the highly ramified suture-line of Ammonites is the thickening of the end-septum of the former. This is improbable, however, for as all the previous septa were capable of withstanding the external excess pressure, there was no need to thicken the last one, and it seems to the writer that this thickening is on a par with the occasional approximation of the last few septa when the animal had reached its full growth. In Wautilus the siphuncle occupies exactly the centre of the supporting septal surface, though, as Dr. Foord has pointed out,° a change of position of the siphuncle during ontogeny is of frequent occurrence in fossil Mautili. The central siphuncular structure of these acted not only as a strengthening feature, as suggested already in 1854 by Pictet,4 who thought it probable that in Ammonoids the complicated septa ‘‘ were necessitated by the excentric position of the siphuncle’’, but the siphon also afforded an additional means of attachment.® In primitive Goniatites the earliest few septa are concave, and it has already been stated that the second septum of e.g. Dactylioceras also tends to be concave and is similarly associated with a simple suture-line and a sub-central siphuncle. When it is further found that e.g. in the Carboniferous Subclymenia evoluta (Phillips), the Triassic Clydonautilus goniatites (Hauer) or the Upper Jurassic Pseudonautilus Geinitzi (Pictet) a nearly external siphuncle is associated with an angular suture-line, it seems, indeed, probable that the shifting of the siphuncle to the external side first started the differentiation and convexity of the septal surface. 1902; also R. Ruedemann, ‘‘ Structure of some Primitive Cephalopods ”’ : Report of New York State Pal. 1903, p. 334, for Piloceras.) They were probably benthonic, and it was only after the shell had become coiled upon itself and bilaterally symmetrical, that the Cephalopod animal could adopt a freely swimming mode of life. 1 “Uber Form und Bau"d. Ammonitensepten und ihre Bezieh. z. Sutur- Linie’’: 4. Jahresber d. Niedersachs. Geolog. Ver., 1911, p. 212. FAOpcite (ps. 212% 3 Cat. of Foss. Ceph. in the Brit. Mus. (Nat. Hist.), pt. ii; Nautiloidea, 1891, p. 322. * Traité de Paléont., vol. ii, pp. 666-7. ° Older authors (e.g. Vrolik & Van Breda, Ann. Mag. Nat. Hist., vol. xii, p. 173, 1843) even held that the animal was attached to the shell only by the siphon. : 122 L. F. Spath—Notes on Ammonites. The writer would like to draw attention in this connexion to the interesting series of Vautil: from the London Clay, which shows the close interconnexion of the various mechanical features of the shell. Nautilus Parkinson, Edwards, which has Aturia lobes (but the siphunele farther away from the dorsum than e.g. the galeate-whorled NV. Sowerbyi, Wetherell, with only slightly undulating septal edges) lacks the wide trumpet-mouthed funnels of typical Aturie where the siphuncle is dorsal. It might be suggested that apart from its connexion with the attachment of the animal to its shell, the differentiation of the septal surface in the neighbourhood of the siphuncle would afford protection for the latter. This would apply especially to the typical Ammonites in which elaboration of the suture-line begins at the siphonal lobe and progresses dorsally as is shown, e.g. in fig. 9 (p. 42) of Swinnerton & Trueman’s paper, and in which external features such as a keel or a groove are similarly interpreted as contrivances for the protection of the siphuncle. It is probable, however, that this is partly also a case of retention of an original feature and gradual elaboration of the first ventral lobe or siphonal collar of the Goniatite radical, in such a manner that in a later Ammonite, e.g. the external saddle of stage 1 = the first lateral saddle of stage 2 = the second lateral saddle of stage 3 = the first auxiliary saddle of the (latest) stage 4.) Pfaff * states that ‘‘as during growth the septal surface increases at the relatively quickest rate on the external side, differentiation must begin here”. But in that case Clymenide, with an internal siphunele, should not show greater elaboration of the suture-line on the dorsum. Here, also, protection for the siphuncle would have to be assumed, and the abnormal position of both siphuncle and deeper lobes suggests derivation of this stock, not from Gyroceras as Frech thinks, but from a Goniatite ancestor with a siphuncle, the position of which may have been unstable (as in the early whorls of most latisellate Ammonoids) but which had already become associated with the region of greatest differentiation of the septal surface. It is necessary to distinguish between the progressive elaboration ‘of the suture-line in the whole order Ammonoidea and the differentiation in certain stocks necessitated by e.g. whorl-shape. The Dimorphoceras—Thalassoceras lineage, e.g., seems to be the first one in which the minor details of the ventral lobe are elaborated, and from Pronorites onwards, and especially during the Permian and Lower Trias, first the lobes and then the saddles of all the stocks show progressive frilling. On the other hand, in more specialized lineages, such as the Devonian Beloceras, already differentiation is most pronounced in the lateral region, though it begins with the primitive ventral lobe. This applies to practically all compressed Ammonoids, as has already been stated, and demonstrates the impossibility of a morphological classification that groups together the above Devonian Beloceras and the Upper Triassic Pinacoceras, simply because these heterochronous homceomorphs possess a compressed shell. 1 See L. F. Spath, Q.J.G.S., vol. lxx, fig. on p. 341, 1914, stages e, f, h, and J. 20 Ops (cits, ps 222% J. B. Scrivenor—A Tin-bearing Mineral from Siam, 123 | -V.—Purrocrrotsm in a Tin-peantnc MinERAL FRoM Sram. By J. B. ScrivEnor, M.A., F.G.S. ‘JN 1915 a heavy concentrate of sand from an unknown locality in Siam was submitted to me for identification. The sand consisted of rather coarse grains of a dark mineral, and finer grains of ilmenite, ‘monazite, tourmaline, zircon, and topaz, with some of the same dark mineral as that occurring in coarse grains. The dark mineral was isolated and examined by partial chemical analysis and by optical methods, the results proving that it was a tin-bearing mineral with a remarkable pleochroism. The specific gravity was found to be 6-913. The chemical examination, carried out by Mr. C. Salter, gave the following constituents: Sn, 74°50 per cent; TiO, 0°17 per cent; and some iron and alumina. Metallic tin was readily obtained on fusion with KCN. Optically the mineral was found to be uniaxial and positive, and it exhibited a very marked pleochroism of deep red to green, suggesting the colours seen in hypersthene. Unfortunately no crystals were available, therefore it was impossible to prove the mineral to be cassiterite, but the optical properties, apart from the pleochroism and the chemical composition, point to that identification. I have little doubt myself that this dark mineral is cassiterite, showing abnormal pleochroism, because in undoubted specimens of that mineral I have frequently noted a less marked pleochroism of (E) carmine to (0) pale green or colourless. This pleochroism 1s not always equally distributed over a section, but may appear in irregular patches that suggest local variation in chemical composition. T have been informed that a similar pleochroism has been noted in a tin-bearing mineral from Nigeria, and have little doubt that it has been observed by mineralogists who have examined numerous tin-ore specimens from elsewhere. I published a note on this pleochroism in my Annual Report (Federated Malay States Government) for 1904, and have mentioned it in subsequent publications, but this specimen from Siam shows the phenomenon in a much more marked degree than any other specimen I have seen, and now that one has time to return to such matters I would suggest that the connexion between coloration, pleochroism, and chemical composition of cassiterite is a subject that might be pursued with some hope of arriving at interesting results. In crystals and in grains, viewed by reflected light, there is a wide range of colour; but in thin sections examined by transmitted polarized light the differences of coloration are more pronounced still. Pleochroism is sometimes present, sometimes not. The most distinct pleochroic effects I have seen are thisdeep red to green, deep brown to a lighter brown, and violet to almost colourless. It would, of course, be necessary to examine large quantities of material before one could ascribe any particular coloration to a particular chemical constituent ; but it is perhaps worth noting one point here in connexion with this Siamese mineral. One might 124 R&R. A. Smith—High-level Deposits on the Chalk. aunine that the TiQ, is responsible for the pleochroism, but a titaniferous cassiterite described in the Mineralogical Magazine for 1911 (‘‘ Notes on Cassiterite in the Malay Peninsula,” pp. 188-20), showed the brown pleochroism noted above. On the other hand, this cassiterite contained so high a percentage of iron that it could be lifted by an electromagnet ; and itis possible that the iron masked any pleochroic effect ‘that, the TiO. might produce were no iron present. VI.—Nore on rae Hieu-teven Deposits on tHE CHatk at Litre Haru, NEAR BeRKHAMSTED.! By REGINALD A. SMITH, F.S.A., British Museum. T a meeting of the Geological Society on January 22 a section at Little Heath, near Bérkhamsted, was described! and discussed ; but both in the papers and in the discussion attention was focussed on the lower part of the section, and the gravel, which is separated by about 6 inches of bull-head from the Chalk, was assigned to the Pliocene and correlated with the Westleton Beds of Prestwich. But the upper beds have an interest of their own, especially for the archeologist who is acquainted with the work of the late Mr. Worthington Smith; and it seems worth while to point out some striking resemblances to deposits in a line running north-east of the site in question. The Little Heath strata referred to are :— 6. Surface-soil with bleached flint-pebbles from the Reading Beds : about 2 feet thick. 5. Pebbly clay and other glacial deposits ae from : PQ 2O Mies ns ne 4. Stratified loamy ‘eouedl A if ; LO SOR a aa A sharp break was noticed between the loamy sands and the underlying gravels, and analogy justifies the treatment of Nos. 4-6 as a series quite distinct from the Pliocene gravel below. The length of the interval may perhaps be determined by archeeo- logical data. No. 4 is a stratified deposit of dark reddish-brown mottled loamy sand, the entire deposit being banded with very fine lines or partings of the grey clay. An abundance of sun - cracks throughout the stratum suggest genial climatic conditions, and indicate that each separate layer became exposed to the air after deposition. Sun-cracks in brick-earth at Caddington, 7 miles distant, were noticed many years ago and illustrated in Man, the Primeval Savage, p- 80, fig. 49, the interstices being filled with later deposits of the same material, in which several floors or occupation-levels were noticed and examined with interesting results. Not only were flint implements of definite types and excellent workmanship collected in situ, but flakes capable of being fitted together again were recovered in quantities, proving that there had been no disturbance of the various surfaces when brick - earth was laid down from time to time. Above the brick - earth, which often ' See Reports and Proceedings, Geological Society of London, January 22, in this number of the GEOL. MaG., pp. 138-41 (issued January 31, 1919). Some Recent American Petrological Iiteratwre. 125 reached a thickness of 20 feet, was what Mr. Worthington Smith called a contorted drift, evidently a glacial deposit, containing ochreous implements swept from a distant surface and perhaps of earlier date than the brick-earth specimens. The same sequence with corresponding implements was observed on two sites at Caddington (595-530 feet O.D. and 250-185 feet above the Lea); at Round Green, one mile north-east of Luton (530 feet O.D. and 178 feet above the Lea); at Whipsnade, 4 miles south-west of Luton (600 feet O.D. and 166 feet above the River Ver); and at Gaddesden Row, 8 miles north of Little Heath, on the other side of the Gade (544 feet O.D. and 184 feet above the Gade). Details of the above discoveries may be found in Arche@ologia, |xvii, p. 49, and in a paper about to be published by the Society of Antiquaries. Little Heath is 550 feet O.D., about the average level of the other sites mentioned, which all have the same relation to the chalk escarp- ment, and are nearly 200 feet above the nearest river. chase reasonable view that the present valleys have been cut down to that extent since the brick-earth was laid down and covered with glacial drift, on what are now the watersheds of several rivers. The brick-earth implements show the beginnings of Le Moustier culture and are quite unabraded. If there is one point.on which the authorities agree it is that the period of Le Moustier coincided with a cold climate, some would say a glaciation. Whether this ‘‘ contorted drift’ is connected with the Boulder-clay found in the immediate neighbourhood is at present undecided, but it may be recalled that James Geikie connected Le Moustier with the Boulder-clay. It is perhaps too soon to expect. the discovery of implements at Little Heath, but beds 4 and 5 seem (on paper) to correspond so closely to the implement-bearing deposits to the north-east that hopes may be entertained of eventual success; so that the newly opened pit may prove to have a human interest, and even a greater scientific value than was recognized at the meeting. VII.—Some Recent AMERICAN PrerrotoeicaL LITERATURE. OR the last few, years many geologists have been unable to keep in touch with the literature of their subject, partly owing to pre-occupation with war work of various kinds and partly owing to the spasmodic arrival in this country of non-British periodicals. The following short bibliographical notes on one limited branch of geological research have been put together in the hope that they may be of use to those who are now returning to their normal avocations, by affording them some idea of what has been done in America in the way of petrological investigation during the last few years. The list makes no pretence at completeness, since the compiler is himself suffering from the difficulties mentioned above, and the abstracts have purposely been made as short as possible, giving merely the barest indication of the contents of each paper, as a guide to readers who may desire to select what is of special interest to them. If the idea meets with approval it is hoped to publish from time to time similar compilations on other branches of geology. 126 Some Recent American Petrological Literature. “ The System Anorthite-Forsterite-Silica,”” by O. Andersen. Amer. Journ. Sci., vol. xxxix, pp. 407-54, 1915. A detailed experimental and theoretical discussion of this system,. which must be treated as one of four components, in order to account for the formation of spinel in some of the ternary mixtures. The results are applied to actual rocks, especially to varieties that contain olivine. ‘‘Crystallization-Differentiation in Silicate. Liquids,” by N. L. Bowen. Amer. Journ. Sci., vol. xxxix, pp. 175-91, 1915. Experiments were undertaken with artificial melts to determine whether sinking or floating of crystals could be obtained. Olivine and pyroxene were found to sink and tridymite to float: the rate of sinking indicates a progressive increase of viscosity with increase of silica. The results obtained are applied to the observations of Lewis on the Palisade sill, and it is concluded that sinking of crystals is of importance even in acid magmas. ‘“The Crystallization of Haplobasaltic, Haplodioritic, and related Magmas,” by N. L. Bowen. Amer. Journ. Sci., vol. xl, pp. 161-85, 1915. The relations of diopside to the plagioclase series are studied by the quenching method of thermal analysis. The facts determined for artificial melts are applied to their natural analogues, and it is concluded that there can be little reason to doubt that crystallization controls the differentiation of the sub-alkaline series of igneous rocks. ‘The Later Stages of the Evolution of the Igneous Rocks,” by N. L. Bowen. Supplement to the Journal of Geology, vol. xxiii, INomSs Lod on oli pe In this long paper Dr. Bowen gives a summary of his conclusions. based on an extensive discussion of the whole problem of the evolution of the igneous rocks, taking into account the results of investigations of the course of crystallization in artificial melts and the theoretical conclusions arising from them. Assimilation and direct refusion of sediments are regarded as unimportant, since they would lead to rock-types such as are never found. The decision is. reached that differentiation is controlled entirely by crystallization, mainly by sinking of crystals and squeezing out of residual liquids, and it is shown that with slow cooling typical rock-series could be formed from basaltic magma, which is probably the primitive type. ‘Differentiation in Intercrustal Magma Basins,” by A. Harker. Journ. Geol., vol. xxiv, pp. 554-8, 1916. This is mainly a criticism and review of Dr. Bowen’s advocacy of differentiation in situ as opposed to differentiation before intrusion. It is pointed out that increase of viscosity in a cooling body of moderate size would soon stop sinking of crystals, and the frequency of small, separate, but obviously related intrusions is insisted on. It is also shown that the great majority of the crystalline schists of igneous origin belong to the calcic branch, indicating the connexion of calcic magmas with tangential thrusting movements. Some Recent American Petrological Literature. 127 “Genesis of the Alkaline Rocks,” by R. A. Daly. Journ. Geol., vol, xxvi, pp. 97-134, 1918. An examination of recent publications has led the writer to renewed faith in the general explanation for most’of the alkaline rocks advanced in Jgneous Rocks and their Origins. Doubts are expressed as to the validity of some of Bowen’s conclusions on this subject. “Internal Structures of Igneous Rocks, their Significance and Origin, with special reference to the Duluth Gabbro,” by F. F. Grout. Journ. Geol., vol. xxvi, pp. 489-58, 1918. A study of the significance and origin of banded structures, which are found to be in nearly every case parallel to the bounding surfaces of the intrusion. The banding is attributed to convection- circulation during crystallization. ‘‘Two-phase Convection in Igneous Magmas,” by F. F. Grout. Journ. Geol., vol. xxvi, pp. 481-99, 1918. Banding and other parallel structures in igneous rocks indicate the occurrence of convection during cooling. The idea of convection becomes of practical service when applied to banding as an indicator of the form of the intrusion, assisting in locating and orienting bands of magnetite and other economic minerals and estimating their probable position and extent. ‘CA Study of the Magmatic Sulfid Ores,” by C. F. Tolman, jun., and A. F. Rogers. Stanford University Publications, 1916. A microscopic and metallographic study of ore-bodies of the Sudbury type, associated with basic intrusions. It is concluded that the magmatic ores in general have been introduced at a late stage asa result of mineralizers and that the ore-minerals replace silicates. The process, however, is distinguished from pneumatolysis, since quartz and secondary silicates are not then formed. ‘Two main types are recognized, namely, nickeliferous pyrrhotite- chalcopyrite deposits in norite and gabbro, and chalcopyrite-bornite. deposits in norite and diorite. ‘‘The Nickel Deposits of the World,’ by W. G. Miller and C. W. Knight. Reprinted from the Report of the Ontario Nickel Commission, l’oronto, 1917. The origin of the Sudbury ores is fully discussed, with detailed descriptions of all the mines: in opposition to the views of Coleman and others the authors consider that the sulphides were deposited from heated waters at a period subsequent to the consolidation of the norite. It is pointed out that the commercial ore-bodies form the cementing and replacing material of breccias along crushed and sheared zones, not in the norite but in the country rock, often at some distance from the contact. Analyses of the norite show little or no evidence of differentiation. 128 Reviews—La Face de la Terre. ‘“Magmas and Sulphide Ores,” by A.-P. Coleman. Econ. Geol., vol. x11, pp. 427-34, 1917. _ A discussion of the work of the Ontario Nickel Commission and of Tolman and Rogers on the Sudbury ores. The author maintains that the field relations there seen are in good agreement with the theory of magmatic segregation under gravity, but inconsistent with the deposit of the ores by circulating solutions. : ‘‘Magmatic Ore Deposits, Sudbury, Ont.,” by A. M. Bateman. Keon. Geol., vol. xu, pp. 891-426, 1917. A description of the field relations and characters of the nickel- bearing ore-deposits of Sudbury, with a discussion of recent views as to their origin. The author’s own hypothesis is that an intermediate magma was differentiated ina reservoir and a portion was extruded to form the ‘‘nickel eruptive”. This portion then continued to differentiate, giving rise to the successive portions, which vary from granite to pyrrhotite-norite and ore-bodies. ‘““On the Geology of the Alkali Rocks of the Transvaal,” by H. A. Brouwer. Journ. Geol., vol. xxv, pp. 741-78, 1917. A detailed petrographical description of the Bushveld complex, with a special discussion of the possible origin of the nepheline syenites and allied rock-types of the Pilandsberg area, Leeuwfontein and Lydenburg. It is concluded that these highly alkaline rocks may have been derived by differentiation from the same magma as the granites and norites of the Bushveld. ‘“The Problem of the Anorthosites,” by N. L. Bowen. Journ. Geol., vol. xxv, pp. 209-43, 1917. The occurrences of anorthosite in the Adirondacks and in the Morin area are described, and it is concluded that the monomineralic rocks of the anorthosite group have probably been formed by gravity- separation of femic minerals from a gabbroid magma. The remaining plagioclase liquid again separates into a basic anorthosite layer below and a lighter syenitic or granitic phase above. (To be continued.) RAV LEws- I.—La Face pe 1a Terre. Tome III, 4¢ Partie (fin). Traduit et annoté sous la direction de E. pE Maxerrin, avec un Hpilogue par Pirrre TermMier. pp. xv and 1861-1724, with 3 coloured maps, 2 plates, and 115 figures. Tables générales de l’ouvrage, pp. 258. Paris: Armand Colin. 1918. Tis with great pleasure that we welcome the appearance of this the concluding instalment of the French version of Das Antlits der Erde, and we congratulate M. de Margerie and his colleagues on the successful termination of their labours, in spite of the adverse conditions of the last four years. Although nominally a translation Reviews—La Face de la Terre. 129 this work should be called rather an edition. Itis true that the text follows as closely as the idioms of the two languages allow the wording of the original German, but it is enriched by such a mass of new references and notes, by so many new figures and maps, that it is almost a new book: in fact, Suess brought up to date. The index volume alone is a large work in itself, and it contains some very useful tables arranged to facilitate the finding of maps and figures referring to particular subjects and areas: these alone occupy 75 pages. It is unnecessary at this time to review the book in the ordinary sense of the word, but it is perhaps permissible to make a few remarks on certain special points that suggest themselves on reading it. In the first place it is pleasing to find that the French editors have in some cases corrected injustices with regard to the assignment of ideas to their true authors: for example, it has been the fashion in German and other foreign petrological literature to attribute the conception of Atlantic and Pacific suites of rocks to Becke, whose work was published in 1902. .An additional note on p. 1542 of this volume states that the idea, though foreshadowed by Iddings in 1892, was formulated clearly for the first time by Harker in 1896, six years before Becke wrote. Although probably unintentional on the part of Suess, this sort of thing is sadly too common in German scientific writings, and such statements are often copied without verification in other countries. Asis probably well known to most people, this part of the book contains a summary of the result of the author’s lifelong work, and some of the conclusions here set forth differ somewhat from those reached in the earlier volumes. Such a study as this, extending over sO many years, was naturally evolutionary, illustrating the development of the author’s views as knowledgeincreased. Of special interest is the importance attached in the chapter entitled ‘‘ Les Profondeurs”’ to the nature of the earth’s interior and the genesis of the igneous rocks. The use of the rather barbarous manufactured terms like Crofesima and Nife is significant of the trend of modern petrological thought in the way of recognizing the desirability of studying the genesis of the metallic ores as well as of the silicates ; the study of the sulphides is now becoming an important part of theoretical petrology, and in this way the work of Vogt, carried out nearly thirty years ago, is bearing good fruit. The epilogue, by M. Pierre 'ermier, of the Académie des Sciences, partakes rather of the nature of a panegyric of Eduard Suess, and shows clearly the veneration of the French school for the great Austrian geologist, in spite of all the events of the last few years. It brings into strong relief the influence of his work on Bertrand and others, work which has largely substantiated and amplified the ideas of the master. The labours of the French editors have carried on this tradition, and there can be no doubt that geologists who wish to gain an insight into the structure of the earth will turn to this rather than to the original German or to the English translation as an exposition of the state of knowledge on this subject at the present time. 1a sys DECADE VI.—VOL. VI.—NO. III. i) 130 Reviews—Discovery of Diamonds vn South A jrica. II.—Tue Discovery or Diamonps in Soutn Arica. By E.J. Dunn, formerly Director of the Geological Survey of Victoria. Industrial Australian and Mining Standard, vol. lx, p. 91, 1918. (WVHIS article, which was reprinted in the Mining Magazine, November, 1918, is a very interesting and readable account of the beginnings of the South African diamond industry, and especially so since the author was present in the very early days of the discoveries, and watched the gradual growth of the mining at first hand, while he also knew personally all the men who played the chief parts in the early development. When he first arrived on the fields in 1871 the presence of diamonds had been known for four or five years, and a considerable amount of work had been done on the river diggings; but the exodus to the dry diggings was only just taking place; the site of the De Beers Mine was a low knoll, and no one had so much as scratched the surface at this place, where the shaft 1s now 3,520 feet deep. The original discovery of the diamonds was quite accidental; the first was picked up by a Bushman herd-boy who gave the ‘‘ blink klip” or bright stone to his master’s children to play with, and it was only after some considerable time that its value was realized. After this finds became gradually more frequent till at last the rush took place and diamonds became a serious factor in the life of the country. Before the discovery the trade and industries of South Africa were at a very low ebb and the country had become almost bankrupt, but the herd-boy’s discovery on the Orange River was the beginning of a period of prosperity which is still continuing, and to which diamonds have contributed to a very considerable extent. IJI].—Tuer GromorpHotocy or THE CoastaL District or Soura- Wesrern Wetrineron. By C. A. Corron. Trans. New Zealand Inst., vol. 1, pp. 212-22. (J\HE fertile coastal district of South-Western Wellington shows certain peculiar physiographic features of comparatively modern growth which appear to be explicable as the result of alternate retreat of the shore-line under wave-attack (retrogradation) and advance of the shore-line due to accumulation of land-detritus (progradation). The author gives an interesting theoretical dis- cussion, with diagrams, of the growth of a coastal lowland under conditions of fluctuating waste-supply, and applies his conclusions to the features of the area under review. It appears that the dominant factor in this instance is a variation in the supply of sand coming from rivers further to the north-east, rather than a fluctuation in the gravel brought down by the local streams. Other possible explanations are also considered. Reviews—Tertiary Beds in the Pareora District. 181 TVY.—Tuer Scccusston or TErrrany Beps 1n THE Pareora Drsrricr, Sour Canrersury. By M. C. Guprx. Trans. New Zealand Inst., vol. 1, pp. 244-62, 1918. -fPVHE Pareora district les about half-way between Christchurch and Dunedin on the east coast of the South Island of New Zealand. The complete sequence of Tertiary beds includes repre- sentatives of the Oamaru and Pareora series, with a total thickness of about 1,250 feet. An enormous number of fossils have been collected, and their detailed occurrences are tabulated at the end of the paper. The lithological character of the beds is very variable, including sands, clays, marls, and limestones, and at the base a series of grits and conglomerates alternating with coal-seams. The coal is apparently inconstant and has a dip of 60°, so that it seems -unlikely to be of commercial value: it appears to have been formed in an estuary or bay and not by growth in place. V.—On roe Ace or roe Atpine CHarin oF Western Ortaco. By James Park. Trans. New Zealand Inst., vol. 1, p. 160, with plate, 1918. f{.HE Alpine chain of Western Otago consists of folded rocks of Lower Paleozoic age, but deeply involved in the eastern folds of the chain is a remarkable narrow strip of Tertiary strata which can be traced for some 25 miles. This has been involved to a depth of at least 4,500 feet. The beds consist of conglomerate, sandstone, clay, and limestone with badly preserved fossils, the maximum thickness being about 80 feet. The fossils indicate an Oamaruian (Miocene) age, probably belonging to the upper part of this forma- tion. This occurrence affords satisfactory evidence that the mountain-building movements took place in post-Miocene times, probably early Pliocene. VI.—Nores on tHE GeroLtocy or THE TuBUAI ISLANDS AND OF Prrearrn. By P. Marswary. Trans. New Zealand Inst., vol. ], pp. 278-9, 1918. ‘hss Tubuai Islands are a scattered group situated near 23° S. lat. and 150° W. long. Little is known of their geology, and Professor Marshall has examined petrographically three stone imple- ments brought thence: two of them are dense, rather acid basalts, while the third is a rather coarse-grained olivine basalt. None of them present any special peculiarities. An examination of a box of rock specimens sent by the Chief Magistrate of Pitcairn revealed the presence here also of fine-grained basalts, many being glassy and probably of submarine origin. Most of them contain a good deal of olivine, and are moderately basic, though less so than varieties described by Michel-Lévy, which were not represented in this collection. 132 Reviews—The Building Stones of Queensland. VII.—Tue Burpine Stones or Quernstanp. By H. C. Ricwarps. Proc. Roy. Soc. Queensland, vol. xxx, No. 8, pp. 97-157, 1918. N the Official Year Book of Australia for 1916 it was found necessary to remark that ‘‘there is not sufficient information available to permit of a detailed statement ... in regard to the quantity and quality of Queensland Building Stones”. This reproach is now largely removed by Dr. Richards, who has given in this paper the geological and physical characteristics of the stones available for constructional purposes. Numerous chemical analyses are quoted, and tables showing the resistance to crushing, specific gravity, absorption coefficient, etc., of many of the rocks, are provided. The papercontains many details of petrographical interest and is illustrated by eighteen photomicrographs. VIII.—Report on tHe Cray Resources or SouTHERN SASKATCHEWAN. ’ By N. B. Davis. Canada, Department of Mines. pp. 98, with 21 plates, 1 figure, and 2 maps. Ottawa, 1918. fJYHE Province of Saskatchewan contains abundant and excellent deposits of fireclay, and of clays suitable for the manufacture of all kinds of ceramic ware, especially bricks and tiles, a fact of much importance in a region devoid of building stone and with little timber. The most valuable clays are found in the lower and middle divisions of the Fort Union formation, of Eocene age, associated with silts, sands and lignite, the best of all being in the White-mud series. The Pleistocene and Recent deposits also include beds of clay suitable for making common bricks. In this report a very full account is given of the technology and properties of the clays with records of numerous tests, and a detailed description of the manner of occurrence and thickness of the beds in a great number of localities. IX.—Ow tHe Inrrvusion Mecuanism or trae ARncHHAN GRANITES OF CenrraL Swepen. By P. Geer. Bull. Geol. Inst. Univ. Upsala, vol. xv, pp. 47-60, 1916. HE older and younger Archean granites of Central Sweden show characteristically different relations to the rocks invaded by them, the earlier intrusions being to a large extent connected with anticlinal structures, while among the younger batholiths two types can be discerned, the anticlinal and the transgressive. The former resemble in this respect the older gneissic granites, while the others, the Serarchean granites of Hogbom, furnish excellent examples of the features quoted by Daly in favour of the hypothesis of intrusion by overhead stoping. Many of these stoped batholiths occur in regions characterized by plateau structure, as defined by Harker; in others this relation is not so typically developed, but the structural relations are always those of the zone of fracture, with regional subsidence and faulting, in strong contrast to the conditions con- trolling the development of anticlinal batholiths which are associated with strong contemporaneous folding and compression of the surrounding stratified rocks. : “hel RA) Reviews—Swedish Archean Structures. 133 X.—Swepish Arcoman Srrvcrures and THEIR Mranine. By P. J. Hormauisr. Bull. Geol. Inst. Univ. Upsala, vol. xv, pp. 125-48, 1916. ROM the evidence brought forward in this paper the following sequence of events seems probable: the porphyry-leptite rocks are the oldest known formation; they represent ashy volcanic deposits, comparable to the Keewatin. These sank in blocks into the underlying granite magma, being metamorphosed and partly assimilated. After the consolidation of this granite magma the whole was affected by dynamometamorphism, forming different varieties of gneissose and schistose rocks of varying grades of alteration, the highest grades of metamorphism being closely connected with pegmatitization. The latest eruptive masses of the Archean consist of very acid granites, pegmatites, and aplites. XI.—Department oF Mines, Canapa, Summary Report, 1917. Parr B. 48 pages, with 1 text-figure. Ottawa, 1918. VHIS instalment of the Summary Report for 1917 contains accounts of geological reconnaissances and surveys in various parts of British Columbia and the Yukon Territory. Most of the areas dealt with contain minerals of economic value, especially gold, and mining is now being developed to a considerable extent. Most of the mineralization is evidently due to the intrusion in Jurassic and early Cretaceous times of the great igneous masses known collectively as the ‘‘ Coast Batholith’’. More detailed work has shown the existence in many places of portions of the original sedimentary roof of this batholith in regions formerly considered to be entirely occupied by igneous rocks. This is of much importance, since most of the ores occur as contact deposits at the junction of the batholith with the older rocks. REPORTS AND PROCHHDINGS. I.—Grotogicat Soormty or Lonpon. 1. January 8, 1919.—Mr. G. W. Lamplugh, F.R.S., President, in the Chair. The following communications were read :— (1) ‘*On ‘ Wash-outs’ in Coal-seams and the Effects of Con- temporary Earthquakes.’’ By Percy Fry Kendall, M.Sc., F.GS., Professor of Geology in the University of Leeds. The author differentiates two types of interruptions in coal- seams which have been confused under the general term of ‘‘ wash- outs”’, ‘‘ wants’’, ‘‘ nips”, or ‘‘dumb-faults”. One type he believes to be due, as geological writers have mostly held, to erosion by contemporary or sub-contemporary streams which coursed through the alluvial area where the coal-material was accumulating as a species of peat. The channel thus cut was subsequently infilled with sedimentary materials. He describes a number of examples of this type in the Midland Coalfield, some being sinuous in course and traceable over many 1384 Reports & Proceedings—Geological Society of London. miles; others being of great width and of irregular form, and due possibly to shifting and meandering streams. Split seams of the type in which the seam rejoins are kindred phenomena, but in these cases the erosion was always contemporary, and, after a channel was filled up with sediments, peat-produen ys plants spread completely across the infilling. Great diversity in the phenomena of splits and wash-outs arises from the differences in the ratios of shrinkage during consolidation of the various SUREELLELIDS, coal undergoing a shrinkage variously estimated from 5%; to 4% of the peat from which it is formed; mud undergoing, as Sorby showed, a considerable though lesser degree of reduction; and sand undergoing almost no reduction at all. ‘hus the hog-back section of split seams is due to the shrinkage of the enclosing coal-substance letting down a relatively incompressible infilling of a channel deeper in the middle than at the sides. In the process the lower surface of the sedimentary mass would flatten to adjust itself to the floor, and the top would consequently assume a curve corresponding generally with the original lower curve, but reversed. The upper element of the seam has some species of seat- earth which arches over the hog-backed inclusion. Cannel, which the author considers to be due toa kind of vegetable pulp that underwent most of its decomposition and chemical change coincidently with deposition, acts as a substance of little com- pressibility ; and, whenever pools of cannel-pulp took the place of an equivalent thickness of normal coal stuff, they survive as swellings in the coal-seam. The infilling of the erosion-channels, usually of muds and sands, which often show current-bedding, sometimes includes masses of conglomerate with, in exceptional cases, boulders measuring up to three feet in length. The pebbles are almost invariably of clay- ironstone, never much rounded, and presumably the product of the erosion of the measures through which the stream has cut its way. Other disturbances of the coal-seams, commonly miscalled ‘‘ wash- outs”’, the author believes to be due to earthquakes, and he holds that in Coal-measure times earthquakes had an importance which | has never hitherto been suspected. The area in which our Coal-measures accumulated he supposes to have resembled generally such alluvial tracts as were the scene of the great earthquakes of Assam and New Madrid described by Mr. R. D. Oldham and Mr. Myron Fuller, save that in the Coal-measures peat- beds were piled in a much more numerous suite, and were on a vaster scale both of thickness and of area than in any part of the modern world where earthquake phenomena have been studied. Some of the effects of earthquakes in Coal-measure times might be expected consequently to be of a magnitude greater than the effects of recent earthquakes, but the types of phenomena are similar. The formation of permanent and transient ridges, ats and fissures, the lurching ont of place of belts of the superficial strata, great displacements by the subterranean flow of quicksand, traces of ‘‘sandblows”’ and of the caving-in of river banks have all been recognized by the author in coal-seams. Reports & Proceedings—Geological Society of London. 185 Disturbances of this character are frequent along the margins of erosion-channels, just as earthquake-formed fissures and ridges are often marked beside recent rivers in alluvial tracts. A striking abnormality in coal-seams consists in the intrusion into the coal of sedimentary material, or the encroachment of masses of amorphous sandstone as ‘‘rock-rolls”. The author attributes these to the invasion of sands rendered mobile by excess of water, and perhaps of gas, and moving under the impulse of waves of elastic compression produced by earthquakes. An earthquake-wave would tend to push forward the water contained in a peat-bed enclosed beneath a cover of laminated clay or mud. Where this cover was impenetrable the effect would be merely transient; where the tenacity of the cover could be overcome, or where it came to an edge through erosion or failure of deposition, water would be ejected from the peat. Ifthis passed into a sand-bed a quite small excess of water, whether accompanied or not by the gases generated in the peat by decomposition, would be sufficient to convert the sand into quicksand; and, in turn, wherever the sand-bed itself was not confined within impenetrable laminated muds there would under the elastic strains of the earthquake be an extravasation of quicksand into adjacent beds, or its expulsion as ‘‘sand-blows”’ at the surface of the ground. When impenetrable mud-beds occurred in a sufficiently yielding condition, such extravasation of sands might carry these beds with them in a more or less stretched condition, and so be perpetuated as solid rolls enveloped in a wrapping of stratified shales. Lurching of the superficial strata took place on a considerable scale. The evidence is found in the gaps (often miscalled ‘“ wash- outs’’) of a type usually narrow and not sinuous, in respect of which the loss of coal is compensated for by swellings or folds of the seam, or by the overriding ofthe seam by great flakes of coal still retaining the characteristics of the seam. These flakes always show torn and ragged edges, which are sometimes splayed out and interpenetrated by tongues of sandstone or of amorphous ‘‘clunch”’, and the fine laminze of the coal preserve their parallel arrangement to the extremities of the projections without contortion. In some cases the flake has been thrown in complicated folds, and in one instance completely inverted. The inference is that the flake of coal was not moved (‘‘ over- thrust’) by any tectonic stress, but that under the impulse of an earthquake a mass of unconsolidated, or but partly consolidated, peat- stuff or lignite was projected forward by its own inertia ina medium, usually of sand, which, through excess of water and gases, had only such resisting power as belongs to a fluid. Such disturbances are (with some doubtful exceptions) always limited to single seams and their contiguous measures, and there is cumulative evidence that usually the coal-stuff, and always the measures, were unconsolidated at the time of the movement. In the overriding flakes the coal retains undistorted vegetable structures in its excessively tender ‘‘ mother-of-coal” layers. The ‘‘cleat”’ in the overriding flakes follows the orientation general to the locality. 136 Reports & Proceedings—Geological Society of London. The gap left by the projection forward of the belt of seam is filled with an unstratified sludge-like substance, commonly containing angular masses of stratified argillaceous or arenaceous material. MINERALOGICAL MICROSCOPES. Dr. A. KRUTCHINSON’S UNIVERSAL GONIOMETER. University Optical Works, 81 TOTTENHAM COURT ROAD, LONDON, W. 1. Watson’ s Wicroscopes for Bas 5 Geology. \ WATSON & SONS manufacture a special series of Microscopes for Geo- logical work. All have unique features, and every detail of construction has been carefully considered with a view — to meeting every requirement of the geologist. All Apparatus for Ceclogy supplied. WATSGN’S Microscopes are guaranteed for 5 years, but last a lifetime, and they are all BRITISH MABE at BARNET, HERTS. W. WATSON & SONS, Lid. “ESTABLISHED _1837)) 313 HIGH HOLBORN, LONDON, W.C. 1. Works:—HIGH BARNET, HERTS. 3 ait Pi nian THE Pow? GHOLOGICAL MAGAZINE NEW SERIES a OCA DE) Vi MOLL AV] ji) bf ae ayy Rey No. IV.— APRIL, 1919. HDITORIATL NOTES. PVVHE Editors of the Grotocrcan Magazine desire to take this opportunity of thanking their friends and subscribers for the kindly expressions of good-will and promises of practical support that have followed the issue of the circular sent out with the December Number. They also wish to say that it is their hope and intention to make the Magazine of service to the geological world as a vehicle for the publication of original work, also as a review of the progress of the science and a means of intercommunication between fellow- workers in different parts of the world. In furtherance of this latter object, they appeal especially to geologists in the British Dominions beyond the seas and in foreign countries to continue to send copies of their publications for review. As a matter of fact, a large number of such publications are actually received, but it is feared that in the last three or four years a good many more never reached their destination. It is certain that a free interchange of ideas between widely separated parts of the world is one of the surest ways of forwarding the progress of knowledge. Geologists in the less developed countries where “fresh fields and pastures new ”’ are constantly turning up, enjoy many opportunities denied to those in regions where field-work and mining investigations have been carried on for over a century and where the great fundamental principles of our science have long been applied and geological features mostly worked out. In new countries geologists and explorers also develop their own theories and represent fresh phases of thought, which should be disseminated as widely as possible for the benefit of mankind at large. The Editors trust that their readers will assist them in their ambition to help in the spreading of new light in the geological world. * % % % % Tne Annual General Meeting of the Geological Society of London took place on Friday, February 21, when the medals and awards were handed to the recipients, whose names have already been announced in this Magazine. A portrait of Dr. Henry Woodward, F.R.S.;. painted by Miss Lancaster Lucas, was formally accepted as a gift to the Society. ‘The President also delivered his annual address, the subject chosen being ‘‘ The Structure of the Weald and Analogous Tracts”. It was pointed out how deep borings have shown that the Wealden anticline is a superficial phenomenon imposed on a huge wedge of Jurassic and Lower Cretaceous rocks forming a deep syncline: the accumulation of the Mesozoic sediments took place in a gradually deepening trough with DECADE VI.—VOL. VI.—NO. IV. 10 wana | th SFist bisa 146 i Editorial Notes. relatively stable sides, and the anticlinal structure was due to a slight reversal of the earlier direction of movement. Similar conceptions were extended to the Jurassic rocks of the Midlands and of Yorkshire; in both cases the recumbent wedge was found to be in evidence, and such structures can probably be traced in Triassic, Carboniferous, and even older rocks. It was also pointed out that where such formations lie above sea-level their outcrops represent areas of maximum development and coincide with the deepest parts of the old troughs. These considerations may be of wide application and have a practical bearing. Tue Report of the Council of the Geological Society of London, presented at the Annual General Meeting on February 21, must be regarded as highly satisfactory considering all the circumstances of the time, since it shows that the Society has been able to keep most of its activities unimpaired. The number of Fellows shows, as might be expected, a slight decrease, and there ure a good many vacancies in the list of Foreign Members and Correspondents. The financial position is satisfactory, in spite of the increased cost of nearly everything, and more especially of paper and printing. The pro- duction of volume Ixxiii of the Quarterly Journal cost over £860 exclusive of postage. The generous action of the Council in remitting the annual contributions of those Fellows on active service has led to a diminution of receipts for some years, but that is now presumably a thing of the past. An increase of income may be expected in the future from the admission of women as Fellows, although this is not likely to be very great, at any rate for some _ time to come. It is well known that the Society’s library has been found of the utmost value during the War to the Admiralty, the War Office, and many other Government departments, since it contains publications, and especially maps, not to be found elsewhere in this country. - It is gratifying to observe that a small sum has been set aside from the Prestwich Trust Fund for the purchase of books’ on economic geology, in which the library is still somewhat deficient. It is certain that the demand for economic literature will increase greatly in the immediate future, and this is a step in the right direction. Tur Cambridge University Reporter for February 18 last announces the subject for the Sedgwick Prize Essay for 1922 as follows: ‘The Petrology of the Arenaceous Sediments of Lower Cretaceous Age in England, with special reference to the Source of the Material.”? The prize, which is triennial and of the value of about £80, was not awarded in 1915 or 1918, as is natural under the circumstances, but even in normal times it has happened that no essays have been sent in. This is possibly owing to one of the conditions: that the prize shall be open to all graduates of the University who have resided in Cambridge for sixty days during the twelve months preceding the date at which the essay must be sent in. This greatly limits the number of possible candidates, since Editorial Notes. 147 few geologists can afford the time to reside for a term in Cambridge for this special purpose. Tue list of fifteen candidates selected by the Council for election to the Royal Society contains several names of interest to geologists. The many contributions of Dr. J. W. Evans to geology and mineralogy are well known to all, as well as his wide experience of travel and his activities at the Imperial Institute. He is also now taking a prominent part in the organization of the new Imperial Mineral Resources Bureau. Dr. W. D. Matthew is a Canadian paleontologist who has contributed largely to our knowledge of the fossil mammals of the North American Continent, especially by his generalizations as to the phylogeny of the Cervide, Felide, and other groups. Sir Charles F. Close, Director-General of the Ordnance Survey, is responsible for the excellent maps which are so invaluable for geological work of all kinds in this country. Mr. E. Heron-Allen, although primarily a protozoologist, recently gave a most interesting lecture before the Geological Society on the application of X-ray photography to the elucidation of the structure of minute fossils, especially Foraminifera, showing results of remarkable technical excellence. % % % * % Tue retirement of Sir Lazarus Fletcher, Knt., M.A., F.R.S., Director of the Natural History Museum, marks the disappearance from active service of the last of the four Keepers who under Professor Owen represented this great section of the old British Museum in Bloomsbury, and were responsible for the transfer of its several collections in 1889 from Great Russell Street, W.C., to their present home in Cromwell Road, South Kensington. Mr. Fletcher, who, after a remarkably brilliant career as a student and mathe- matician at the University of Oxford, entered the Museum as a First-class Assistant in Mineralogy in March, 1878, succeeded Professor Story Maskelyne as Keeper of Minerals in 1880, a post which he held for twenty-nine years, being made Director of the Museum in 1909, and retiring after ten years in the month of March. During this long period of forty-one years Sir Lazarus Fletcher has rendered important services to science and to the Museum; amongst others may be specially mentioned the arrangement of the entire Mineralogical Collection, and the preparation and publication of a most admirable series of Guide-books, namely, an Introduction to the Study of Meteorites, 1881; to Minerals, 1884; to Rocks, 1895; and, still earlier, an Optical Indicatrix in 1872. Numerous are the honours, medals, and awards which have been conferred upon Sir Lazarus Fletcher, but notwithstanding he is probably one of the most modest, reserved, and retiring scientific men of eminence in London. % % % # # Tae Zimes of March 13 last announced the appointment of Dr. Sidney Frederick Harmer, F.R.S., as Director of the Natural History Museum in place of Sir L. Fletcher. Dr. Harmer, who is the son of 148 Editorial Notes. Mr. F. W. Harmer, M.A., F.G.S., was formerly Fellow of King’s College, Lecturer in Zoology, and Superintendent of the University Museum of Zoology at Cambridge. In 1907 he was appointed Keeper of Zoology at the Natural History Museum, and it is under- stood that he will continue to hold this post for a time, conjointly with the Directorship. Dr. Harmer has specialized in Invertebrata, especially Polyzoa, and with Dr. Shipley, now Vice-Chancellor of the University, he edited the Cambridge Natural History. Geologists may feel every confidence that in Dr. Harmer’s hands the interests of their science will receive due consideration, and that every facility will be afforded to enable the specialists in charge of the different branches of the Museum to maintain the high standard of the collections and to continue their invaluable work of investigation and research. This appointment is very satisfactory also in that it shows the success of the protest put forward by many leading zoologists and geologists against the proposed appointment of a layman to this important post, which may be regarded as the blue ribbon of the biological world. Tar Mining Magazine for February last contains a reprint of an interesting lecture by Mr. J. Morrow Campbell on the minerals of the Tavoy district of Burma, a region which has lately come into so much prominence as a producer of tungsten ores. As is well known, the origin and mode of occurrence of the ores in Tavoy have led to a good deal of controversy. Without entering in any way into the merits of the rival theories, it is perhaps permissible to point out the great interest which attaches to such investigations from the scientific as well as from the practical point of view. The origin of ore- deposits and the laws governing their formation are matters within the province of the theoretical petrologist just as much as the study of the silicates, and they possess the added advantage of possibly leading to results of practical value in the prospecting and locating of valuable mining areas. If it can be established, as seems possible, that ores of particular metals commonly show definite relations to one another and to certain types of igneous rock, it will become possible to draw conclusions as to the probability of successful development of metalliferous areas by exploration of a particular kind, such as diamond drilling, for example. As a concrete instance the well-known relations of copper and tin ores in Cornwall may be mentioned, or the association of platinum with serpentine, which actually led to the discovery, based on scientific reasoning, of platinum in the Serrania de Ronda in the South of Spain. In this way the theoretical and the practical geologist can work hand in hand for their mutual benefit and the good of the science in general. * 1 * Arrer two years’ interval owing to war conditions, the British Association for the Advancement of Science will resume its series of annual meetings this year at Bournemouth, from September 9 to 13, under the presidency of the Hon. Sir Charles Parsons, K.C.B., F.R.S. ORIGINAL ARTICLES. EER T.—Camesriran Hyori”, Erc., From Harrsnirt in roe Nuneaton Districr, WARWICKSHIRE. By E. S. Copsoup, F.G.S. (PLATE IV.) ROFESSOR CHARLES LAPWORTH, in his ‘‘ Sketch of the Geology of the Birmingham District”’,’ gives a list of species (pp. 848 and 349) from ‘‘the Hyolite Limestone ” and the associated shales as provisionally determined by Miss E. M. R. Wood (Mrs. Shakespeare). He referred the beds generally to the Lower Cambrian and paralleled them approximately with the fossiliferous - beds of Comley, the details of which had not then been worked out. The present study of the Hyolithide, ete., of Woodlands Quarry, fully confirms the reference to the Lower Cambrian, and it would seem that the position of the Hyolite Limestone in the faunal sequence is near to or a little below that of the Olenellus and Grey Limestones of Comley at the local summit of the Lower Cambrian. The evidence of this is indirect, for no species has yet been identified from both localities, unless it be Mdicromitra labradorica, Billings sp. Nevertheless, the Hyolithidz, etc., found in North America that are nearest to, or representative of, those of Hartshill, are there associated more or less intimately with a number of trilobites and brachiopods that find their representatives in the Comley Limestones. To put the matter in another way: the Hyolithide, etc., of Hartshill, combined with the trilobites of Comley, make up what is practically the same Lower Cambrian fauna that is found at North Attleboro’, Massachusetts, in the exposures of Manuel’s Brook, Newfoundland, and at many intermediate positions. During the past four years Mr. L. J. Wills, F.G.S., has kindly sent me, for comparison with the forms found at Comley, a number of specimens that he had collected from Woodlands Quarry. This communication is the result of a critical examination of these specimens, without any previous reference to Mrs. Shakespeare’s determinations above alluded to. The specimens are preserved in the Birmingham University collection, and are found upon a number of pieces of red sandy limestone, specially characterized by plentiful tubes of Coleoloides and Hyolithus. A few other fossils occur and also some very obscure fragments of trilobites which are quite indeterminable: Where unweathered the rock is of a dull purplish-red colour, on which the white sections and fragments of shells stand out clearly. Usually the examples are very unsatisfactory for the shells break open tangentially and rarely show their surface characters. Where weathered the rock becomes brick-red and the fossils occur as casts or partially weathered exteriors, which may be more or less completely freed from the matrix. Invagination of shells is very frequent, as many as three or four shells of the same species are sometimes found one within another, 1 Proc. Geol. Assoc., vol. xv, pt. ix, 1898. 150 HE. S. Cobbold—Cambrian Hyolithide from Hartshill. and, where they have the same orientation in cross section and are closely approximated, they give the appearance (noted by Billings? for H. communis) of the individual shell being ‘‘ thickened by concentric lamin, and thus approaches the structure of Salterelia’’. A few detached opercula occur, usually very indifferently pre- served, and it is impossible to say, without reserve, to which species they belong. Descriptions of Species. HYOLITHUS, Eichwald. Sub-genus Orrnoruuca, Novak. Hyolithus ( Orthotheca) de Geert, Holm. (P1. 1V, Figs. 1-6 and (?) 7-9.) Hyolithus (O.) de Geert, Holm, Sver. Geolog. Undersékning, ser. C, No. 113, p. 54, pl. i, figs. 25-7, 1893. Orthotheca de Geert, Holm, Lapworth, Proc. Geol. Assoc., vol. xv, p. 345, 1898. Shells referred to this species are very plentiful in the collection. They agree closely with Holm’s figures and description, the only difference observed being that the apical angle varies from 12° to 8° (taper 1 in 5 to 1 in 7) instead of from ‘9° to 8°”’, The ratio of the sectional diameters also varies somewhat, but is always near to 3 to 2.2. The surface has a texture as of ground glass, with very faint strize of growth, which are transverse on both dorsal and ventral sides. The aperture is frequently seen, but in no instance has the apex been preserved. In two cases the internal cast has a smooth convex end representing a septal division below which the shell has been apparently decollated. Operculum.—A few examples of opercula occur that are referred with reserve to this species. In outline they agree with the transverse section of the principal shell; the margin is practically in one plane; the nucleusis situated at about two-thirds of the diameter from the dorsal edge ; the semi-conical portion is clearly marked off by two radiating lines, and in addition to these, on the exterior surface, two other radiating lines are seen, marking off triangular portions on each side similar to those of the opercula of Hyolithus, sens. strict., at the places where the curvature changes from the conical (dorsal) portion to the upturned (ventral) part; at the bases of these triangles the margin is seen in a side view to be a little depressed from the general plane; the ventral margin is marked by a slightly raised, rounded fillet, between which and the nucleus there is a pit-like hollow. H. (0.) Johnstrupi, Holm,* has a cross section that is somewhat similar, but the dorso-ventral diameter is proportionately greater and the surface marks are described as being rather strong. Hl. primevus, Groom,* from Malvern, has a very similar cross section but a rather greater apical angle (10° to 11°) and indications ! Billings, Canada Naturalist and Geologist, ser. 11, vol. vi, p. 214. 2 Where the ratios of the diameters are mentioned in this paper it is intended to indicate those of the width to the dorso-ventral diameter. > Op. cit., p. 56, pl. i, figs. 28-38. 4 Q.J.G.S., vol. Iviii, p. 116, 1902. E. S. Cobbold—Cambrian Hyolithide from Hartshill. 151 of longitudinal strie; it is uncertain whether this species is an Orthotheca or Hyolithus. H. (0.) Emmonsi, Ford,’ appears to be the nearest American species; the cross section and rate of taper are very similar, the principal distinguishing feature being a shallow hollow all along the dorsal side, making it slightly concave. Horizon and Locality.—Lower Cambrian : red sandy limestone. of Woodlands Quarry, Hartshill. (?Sub-genus) Hyorrrnus® (Holm). Hyolithus (H.) alatus, sp. nov. (Pl. IV, Figs. 18-15 and (?) 16.) ? Hyolithus cf. obscurus, Holm, Lapworth, Proc. Geol. Assoc., vol. xv, pt. ix, p. 343, 1898. Type-specimen [34 ].° Diagnosis.—Shell slightly curved toward the ventral side, taper about 1 in 4 (equivalent apical angle 14°); greatest length about 24 mm., diameter of aperture 6mm.; apex having the same rate of taper as the remainder of the shell, often filled with calcite, but no septa have been observed. Section, dorsal face gently convex centrally, almost concave towards the lateral angles which form rounded projections, ventral face strongly convex centrally, slightly concave towards the lateral angles, ratio of axis 1:°6. Surface, resembling ground glass, but marked with strie of growth, which are transverse on the ventral side, but convex forwards on the dorsal. Aperture in two planes, dorsal lip projecting to a distance equal to about two-thirds of the longer diameter ; ventral lip a little sinuous, with a rounded notch on the centre line. Operculum (?): several examples occur which are assigned with little hesitation to this species. In the view of the operculum as usually seen the outline is nearly circular (Fig. 16), but when the plate is tilted so as to bring the dorsal margin parallel to the line of sight the outline conforms very closely to the section of the shell. In the circular view the nucleus is distant about four-fifths of the diameter from the dorsal margin, and the sides of the conical part meet at an angle of 110° to 120°; the ventral portion is strongly coneave and rises in front (the upper side in the figure) like an upturned brim to a soft felt hat to about twice the height of the nucleus. The curve joining the ventral to the dorsal margin is slightly indented in correspondence with the alate lateral angles of the shell. Comparisons with other species—The section of H. alatus is of the same character as that, of Hyolithus sp. a, Groom,* but is not provided with a ‘“‘blunt keel”, and the proportion between the diameters is different. The species is readily recognized by its alate cross section. HT. obscurus® has two impressed lines on the dorsal side close to 1 Amer. Journ. Sci., ser. WI, vol. v, p. 214, figs. 3a-e. = Tt seems doubtful whether Hichwald’s genus Hyolithus can be used, sens. str., also as a swb-genus.—H. W. * Numbers in square brackets are those attached to the blocks on which the specimens are found. * Groom, op. cit., 1902, p. 116. ° Holm, op. cit., 1893, p. 76, pl. v, figs. 29-33. 152 EH. S. Cobbold—Cambrian Hyolithide from Hartshill. each lateral angle; these cause the angles to project something like those of H. alatus; the ventral side is, however, bluntly keeled. Horizon and Locality.—Lower Cambrian: red sandy limestone of Woodlands Quarry, Hartshill. Hyolithus (H.) biconvexus, sp. nov. (Pl. IV, Figs. 10-12.) ? Hyolithus ef. lenticularis, Linnarsson, Lapworth, Proc. Geol. Assoc., vol. xv, pt. ix, pp. 343, 349, 1898. Diagnosis.—Shell straight, taper 1 in 3 to 1 in 4 (equivalent apical angle 18° to 14°), length of type-specimen 14 millimetres, diameter of mouth in another specimen 5 mm. Section biconvex, dorsal face moderately convex, ventral strongly convex, ratio of diameters 1 to ‘66, lateral angles rather sharply rounded; aperture in two planes, dorsal lip projecting but little; surface marked by fairly strong ridges of growth, spaced about eight to the millimetre in the body of the shell, but closer near the aperture, and having a tendency’ to be alternately strong and weak; the ridges are strongly bent forwards on passing the lateral angles; interior, surface apparently smooth. Operculum (?): one or two examples of opercula that may belong to this species have been found. They are constructed on the same general lines as those assigned to H. alatus, but are more oval in outline as usually seen in the rock, the ventral margin does not rise to so great a height above the convex conical portion of the plate, and the sides of the conical portion meet at an angle of about 90°. Comparison with other species.—H. biconvezus has a similar section to that of H. acadica (Hart MS.), Walcott,’ which, however, has faint longitudinal striz and a greater apical angle. The Middle Cambrian form H. socialis, Linnarsson,? has a some- what similar section, but a smaller apical angle, and is provided with a rounded keel on the ventral side. Hf. lenticularis, as figured by Holm,® has its dorsal and ventral sides equally convex. Horizon and Locality.—\Wower Cambrian: red sandy limestone of Woodlands Quarry, Hartshill. Hyolithus (H.) Wilisi, sp.nov. (P1. IV, Figs. 17, 18.) 2? Hyolithus ef. princeps, Billings, Lapworth, op. supra cit., pp. 343, 349. The type-specimen [27 and 28] exhibits a fragment of the dorsal face together with (on the other side of the piece of limestone) the much-weathered ventral face, from which the outline of the shell may be reconstructed; two oblique sections are also visible. Diagnosis.—Shell large, straight, tapering at the rate of 1 in 2°6 (equivalent apical angle 22°). Section uncertain (the specimen 1 U.S. Geol. Surv., Bull. 10, 1884, p. 20, pl. ii, fig. 5. * Holm, op. cit., 1893, p. 78, pl. i, figs. 72-7. 2 Id., p. 77, pl. v, figs. 23-8. E. 8. Cobbold—Cambrian Hyolithide from Hartshill. 153 has uneven surfaces, indicating some amount of damage or com- pression when freshly embedded in the matrix), ratio of axes (as preserved) 1 to -5; aperture in two planes, dorsal lip projecting a distance equal to one-third of the width (in the type-specimen it is somewhat emarginate at the central line); surface marked near dorsal lip with obvious lines of growth, elsewhere unknown ; internal surface finely granular; dimensions, the complete shell (as reconstructed) would be about 63 millimetres long and the width of aperture (as preserved) is about 20 mm. Comparison with other species.—H. Willsi is only exceeded in size by the Bohemian species 1. giganteus, Novak’ (Ordovician), and H, maximus, Barrande (Middle Cambrian).* Itis of about the same length as H. princeps, Billings,? which, however, is much more acuminate. H, Wiilst agrees closely in some respects with H. excellens, Billings,‘ from the Red Limestone of Trinity Bay, Smith’s Sound, Newfoundland. ‘The Hartshill species has the same length, width, rate of taper, and projection of dorsal lip, but its other characters (convexity and surface marks) are unknown, and until further material is available from Hartshill it seems best to describe it under a new specific name. Horizon and Locality.—Lower Cambrian: the red sandy lime- stone of Woodlands Quarry, Hartshill. Hyolithus (Z.) equilateralis, sp. nov. (Pl. IV, Figs. 21, 22.) Type-specimens [ 25, 2]. Diagnosis.—Shell straight and tapering uniformly, so far as known, at a rate of about 1 in 5 (equivalent apical angle about 12°), apex not preserved. Section, dorsal face very gently convex, lateral angles rounded, ventral face consisting of two surfaces which are very slightly, if at all, more convex than the dorsal and are joined by a rounded angle, the whole forming an equilateral triangle ; aperture in two planes, dorsal lip projecting to a distance of about one-quarter of the diameter, exterior not known. Remarks.—This species seems somewhat scarce; where the cross section can be observed it is easily recognized, but otherwise it is difficult to distinguish it from some views of H. (O.) de Geert, with which it agrees in the rate of taper. Itis near to H. Americanus, Billings,’ which has a similar triangular section, but is not so equilateral; the projection of the dorsal lip also appears to correspond. The exterior of that species is marked by transverse lines of growth and longitudinal striz. Horizon and Locality.—Lower Cambrian: the red sandy limestone of Woodlands Quarry, Hartshill. 1-K. Bohm. Gesell. der Wissensch., Folge vii, Band iv, No. 4, p. 19, pl. iv, figs. 40-50, 1891. 2 Sil. Syst. de Boheme, vol. iii, p. 5, pl. x, figs. 22-9, 1867. > Can. Naturalist and Geologist, N.S., vol. vi, p. 216, 1872. $1d., p. 471. > Billings, op. cit., 1872, p. 215. 154 £. 8. Cobbold—Cambrian Hyolithide from Hartshill. Satreretta, Billings. Salterella (?) curvata, 8. & F. (PI. IV, Figs. 16a, d.) Salterella curvatus, S. & F., Bull. Mus. Comp. Zool. Harvard, vol. xvi, p. 34, pl. ii, fig. 22, 1888. A a a Walcott, Tenth Ann. Rep. U.S. Geol. Sury., p. 625, pl. Ixxix, figs. 3, 3a, 1890. bi Fe iN Grabau, Occ. Papers Boston Nat. Hist. Soc., vol. iv, p. 660, pl. iii, 1900. ‘'wo specimens on one block [38] in the collection suggest a reference to Shaler and Foerste’s species; they lack, however, the cone-within-cone structure of shell that characterizes the type species for the genus Salterella rugosa. ‘They are curved tapering tubes with a rounded or somewhat oval section, scarcely three millimetres long and less than one mm. in diameter. ‘he aperture is not seen, the open ends being fractured. ‘he shell is thick; its outer surface is smooth but marked near the apex with very faint transverse strie spaced about eight to the millimetre. The interior is also smooth, and though filled with calcite shows no trace of annulations or septal divisions. The rate of taper is about 1 in 4, equivalent to an apical angle of 14°. Horizon and Locality.— Lower Cambrian: the red sandy limestone of Woodlands Quarry, Hartshill. CotrotorpEs, Walcott. Coleoloides typicalis, var. multistriata, var.nov. (PI. LV, Figs. 30, 32.) Coleoloides typicalis, Walcott, U.S. Nat. Mus. Proc., vol. xii, pl. xxxvii, 1889. zs a ae U.S. Geol. Surv., Tenth Ann. Rep., p. 624, pl. lxxix, figs. 6, 6a, 1890. Sy 40 35 Lapworth, Proc. Geol. Assoc., vol. xv, pt. ix, ‘p. 343, 1898. Straight tubes of circular section with very slight taper are plentiful in the rock specimens to hand, but very rarely preserve the original surface. In two instances [15 and 38], however, the external surface marks are perceptible: they are very closely set spiral lines, numbering about seventy in the whole circumference of the tube, which is one millimetre in diameter ; they are inclined at such an angle as to make one complete circuit ‘of the tube in a length equal to about 10 diameters. C. typicalis, Walcott, as figured, has much fewer spiral lines and they are set at a more acute angle. The tubes vary in diameter from 1 to 1:3 millimetres. Horizon and Locality.—Lower Cambrian: red sandy limestone of Woodlands Quarry, Hartshill. BRACHIOPODA. Micromirra (Meek), Walcott. Micromitra cf. Phillipst, Hall, sp.) (BIL Ve Bic. 25.) Obolella Phillipsi, Holl, Q.J.G.S., vol. xxi, p-. 102, figs. 10a—c, 1865. O. (2) Phillipsi (Holl), Davidson, Pal. Soc. Mon. British Fossil Brachiopoda, vol. iii, pt. vii, p. 62, pl. iv, figs. 17-19, 1866. E. 8. Cobbold—Cambrian Hyolithide from Hartshill. 155 Kutorgina cingulata, Davidson, id., p. 342, pl. i, fig. 25, 1871. K. cingulata Phillipsi (Holl), Matley, Q.J.G.S., vol. lviii, p. 145, 1902. Micromitra (Paterina) Phillipsi (Holl), Walcott, U.S. Geol. Sury. Mon., vol. ii, p. 351, pl. iii, fig. 8, 1912. One external cast of a ventral valve and a few obscure fragments are very like specimens obtained at Malvern and Comley. The general outline and surface characters agree with MHoll’s species, but, in the absence of further specimens and particularly those showing the false area and pseudodeltidium, the reference is made with considerable reserve. Horizon and Localityn—Lower Cambrian: the red sandy lime- stone of Woodlands Quarry, Hartshuill. GASTEROPODA. Pratryceras, Conrad. Platyceras cf. primevum, Billings. (PI. 1V, Fig. 34.) Platyceras primevum, Billings, Can. Nat., N.S., vol. vi, p. 220, 1871. ne Be AS Walcott, U.S. Geol. Surv., Bull. 30, p. 130, : pl. xii, figs. 5, 5a, 1886. a a ae Grabau, Occ. Papers Boston Nat. Hist. Soc., vol. iv, pt. ili, p. 628, pl. xxxi, figs. 7a, b, 1900. A single specimen [37] consisting of an internal cast of a whorled shell with oval aperture appears to be nearly allied to or, possibly, identical with Billings’ species. In the absence of better preserved specimens the reference must remain doubtful. Horizon and Locality.—Lower Cambrian: the red sandy limestone of Woodlands Quarry, Hartshill. Hetctonrrna, Grabau & Shimer. Felcionella (?) emarginata, sp.nov. (Pl. IV, Figs. 26, 27.) The type-specimen [46] shows two internal casts, from. one of which a fragment of the external cast was preserved during develop- ment, indicating the character of the surface. Diagnosis.—Shell strongly recurved so that the apex projects beyond the limit of the posterior margin; aperture almost circular, slightly flattened anteriorly owing to the presence of a rhomboidal notch; apex (in the cast) somewhat blunt; exterior with many irregular raised lines of growth, some of which are more pronounced than others; allconform in shape to the apertural notch; no radiating striz detected in the material to hand; interior marked with several, irregularly arranged raised concentric lines, seen as depressions in the cast, in addition to which there are in one of the specimens (Fig. 26) two symmetrically arranged rounded and _ ill-defined depressions, that simulate muscle-scars of Brachiopoda, but it seems more probable that they are somewhat fortuitous and possibly connected with the trace of the apertural notch. Dimensions.—Length of aperture about 4°5, width 5, height 2°5 mm. Observations.—So far as known to the writer the aperture of Helcionella is entire. The notch in this species is suggestive of 156 £#.S. Cobbold—Cambrian Hyolithide from Hartshill. Bellerophon, and it is possible that it should be relegated to a new genus and placed among the Heteropoda. The general form is suggestive of the ventral valve of an elevated Brachiopod, but the notch being at the anterior margin cannot be a pedicle opening. Pelagiella, Matthew,’ and Watsonella, Grabau,? have similar notched margins, but are very different in other respects. Horizon and Locality.—Lower Cambrian : _ the red sandy limestone of Woodlands Quarry, Hartshill. Srenorueca (Salter), Grabau & Shimer. Stenotheca abrupta, Shaler & Foerste (?). (Pl. IV, Figs. 28, 29.) Stenotheca rugosa, var. abrupta, S. & F., Bull. Mus. Comp. Zool., vol. xvi, p- 29, pl. i, figs. 9a, 6, 1888. S.(?) rugosa, var. abrupta (S. & F.), Walcott, Tenth Ann. Rep. U.S. Geol. Surv., p. 617, pl. Ixxiv, figs. 6, 6a, 1890. S. abrupta (S. & F.), Grabau, Occ. Papers Boston Nat. Hist. Soc., vol. iv pt. ii, p. 637, pl. xxxi, figs. 12a-c, 1900. i A few internal casts agreeing closely with Walcott’s figures seem to indicate the presence of this form. They show from six to ten rounded corrugations; the section is an elongate oval with the axes in the proportion of 1 to ‘5; the apex is curved over so as to stand approximately above the posterior margin of the aperture. Exterior not observed; no thickening of the ventral margin, such as is spoken of by Grabau (op. supra cit.) has been detected. Dimensions (of largest specimen): length 5, width 2°5, height 4°5 mm. i the absence of good exteriors of these shells it seems doubtful whether they should not be referred to Helcionella, the genus pro- posed in 1910 by Grabau & Shimer for forms congeneric with Metoptoma rugosa, Hall. It is consequently necessary to give the. _ specific reference with reserve. Locality and Horizon.—Lower Cambrian: the red sandy limestone of Woodlands Quarry, Hartshill. LAMELLIBRANCHIATA. Forpitta, Barrande. Fordilla troyensis, Barrande(?). (PI. IV, Fig. 33.) Fordilla troyensis (Barrande), Walcott, Bull. U.S. Geol. Surv., No. 30, p. 125, 1886. Ke an a Walcott, Tenth Ann. Rep. U.S. Geol. Surv., p. 615, pl. lxxiii, figs. 2, 2a—c, 1890. >» i a Grabau, Occ. Papers Boston Nat. Hist. Soc... vol. liv, pt. iii, pp. 610, 611, 633, 1900. A single shell occurs with the Hyolithide from Woodlands Quarry agreeing in many respects with Walcott’s figures for this species. It appears to be the somewhat worn exterior of a left valve, and is about 3mm. long with the umbo situated a little in advance of the mid-length. No radial striz are preserved, and the concentric lines of growth are not so thickly set as those shown i in Walcott’s figures. 1 Trans. N.Y. Acad. Sci., vol. xiv, p. 131, 1895. 2 Op. cit., p. 631, 1900. Prats LY. Grou. Maa., 1919. Bale & Sons, vine. EB. 8. Cobbold, del. =) E. S. Cobbold—Cambrian Hyolithide from Hartshill. 157 Horizon and Locality.—Lower Cambrian: the red sandy limestone of Woodlands Quarry, Hartshill. I desire to express my gratitude to Mr. L. J. Wills for allowing me to study and describe his specimens, and also to Dr. F. A. Bather for much kind help in reference to the literature of the genera Salterella, Stenotheca, and Helcionella. EXPLANATION OF PLATE IY. Note. —The numbers in square brackets are those attached to the blocks on which the specimens are found. All belong to the collection of the Birmingham University. Hyolithus (Orthotheca) de Geert, Holm. x 2. (See p. 150.) Fie. 1[87]. Ventral side; a, exterior; b, section. 2[36]. Dorsal side, showing transverse lip; @, internal cast; 6, section. 3 [34]. Ventral side, showing transverse lip; a, external cast; 6, section. 4[29]. Op. cit., vol. ii, p. 669. 6 Yorkshire Type Ammonites, vol. ii, pt. x, p. 76, pl. Ixxvi, 1913. 7 Definitely given as “‘ capricornum zone’? in Mr. Buckman’s ‘* Paleonto- logical Classification, ete.’’, in The Geology of the Country between Whitby and Scarborough (Mem. Geol. Surv.), 2nd ed., 1915. L. F. Spath—Notes on Ammonites. 171 Wright! expressed the opinion that von Buch had considered the suture-line of much greater importance than was justified by later observations, and he stated: ‘‘ In adult life, however, the form of the suture-line is a valuable character.’”? H. Douvillé,* ten years later, took an exactly opposite view. He thought that the best family characters would have to be furnished by the plan of the suture-line, i.e., its general course in the post-goniatitic stage before it was masked by the complication of the lobes and saddles. Fischer,* on the other hand, thought that ‘‘the suture-line was of real value for classificatory purposes only when used in conjunction with other characters ofa ‘higher’ order, such as the general form of the shell, its ornament, mouth-border, or aptychus. If the suture-line were the absolute basis for a classification of Ammonites, this would have been accomplished long ago, since from von Buch’s time onward all paleontologists had kept this character in view. Unfortunately no one could affirm to-day that there exists a satisfactory classification of this group of cephalopods”’. Noetling* also thought that the systematic value of the suture- line was not very great, since the protrusions of the visceral hump that went into the lobes were of noimportance. Opinions may differ on this latter point, for in living animals even specific differences are often very fundamental and extend to quite minor internal structures or to the convolutions of the brain.® It is not the writer's intention to give a complete history of the alternate favouring and disfavouring of the suture-line as a basis for the classification of Ammonoids, but it is surprising that, though opinions on its value were freely given, little research as to the nature and origin of the folded septal edge was carried on. It must be admitted, however, that among modern workers on Ammonoids many look upon the suture-line as the dominant feature, and Hyatt ® even went so far as to say that ‘all classifications were necessarily based upon sutural peculiarities”. In view of the importance of this statement it seems advisable to examine the other features of the Ammonoid shell that have been used for classificatory purposes. With regard to the form of the shell and the coiling, their value for a natural classification of Ammonoids is strictly limited. Few authors would now group certain Inferior Oolite forms (Patoceras) 1 Monograph of the Lias Ammonites, Pal. Soc., 1880, p. 219. Only seven years after the compilation of Wright’s work, hailed at the time of its appearance as a “‘masterly monosraph’’ (A. Geikie, Text-Book of Geology, 1882, p. 786), Professor Blake (‘‘The Evolution and Classification of the Cephalopoda, ete.’’: Proc. Geol. Assoc., vol. xii, p. 292, 1892) had to say with regard to the classification adopted by Wright, namely that of Neumayr, originally published in 1875: ‘‘Its author, were he happily still with us, would certainly regard it as quite inadequate and out of date at the present time.’’ 2-**Sur la Classification des Cératites de la Craie™ : Bull. Soc. géol. France, ser. 11, vol. xviii, pp. 280, 291. : Discussion on aboye, ibid., pp. 291-2. * Op. cit., 1905, pp. 59-60. ° A. vy. Tschermak, ‘‘ Uber d. Entwicklung d. Artbegriffs’’: Tierarztl. Zentralblatt (34), Vienna, 1911, pp. 351, 381. § In Zittel-Hastman, Textbook of Paleontology, 1st ed., vol. i, p. 546, 1900. ee L. F. Spath—Notes on Ammonites. with the Cretaceous Ancyloceras or Toxoceras, as, e.g., d Orbigny and Pictet did, simply because they are of a similar shape. ‘here is no generic connexion among most of the scaphitoid or other ‘“‘aberrant’’ forms that appear at a number of horizons and may originate from very distant stocks, though they have a similar form. De Loriol’ describes an aberrant form that occurs together with Cardioceras cordatum as Cicoptychius Christoli, Beaudouin. It is evident that this form has no connexion with the earlier type of Geoptychius, namely @. refractus (de Haan), from the anceps zone. There is not even similarity of shape, and the form is probably a modified development of some contemporaneous group of Ammonites such as Pachyceras. It has also been mentioned already that it is impossible to group together the Devonian Biloceras and the Triassic Sageceras, or the Cretaceous Garnierta and the Liassic Oxynoticeras, simply because they are similar in appearance. It will be noticed that geological occurrence isa determining factor in the separation of many of these lineages based on a modified whorl-shape ; Spiroceras is strictly Callovian, Aneyloceras confined to the Lower Aptian. Unfortunately this has given rise to a multitude of new names, but the creation of separate genera for the various abnormal whorl-shapes antedates the splitting up of the genus ‘‘Ammonites”’ by Suess, Hyatt, and Waagen. Impossible as it may be to use form and coiling of the shell for a general classification, certain Ammonites (e.g., Phylloceras) can at once be recognized by their form, and when this is modified (e.g., in Sowerbyceras) a separate name is given to the new stock. The same thing applies to the coiling in Zytoceras where evolution gives rise to, e.g., Costediscus and Macroscaphites. In the great majority of Ammonites, of course, form and coiling vary considerably within a genus; e.g., in Cadoceras there are compressed shells and greatly depressed cadicones, in I/orphoceras there is involution and evolution, in Schlotheimia the whorl may become almost oxynote (S. Greenough). When form and coiling change within a species group, what older authors termed thick and thin, evolute or involute ‘‘ varieties”’ of the species are produced. But the term ‘“‘ variety ”’, which has a definite zoological meaning, is not favoured by modern paleontologists, who, on the other hand, often do not make enough allowance for individual variation within a species. It may be inadvisable to give a new name to every form that differs, often only very slightly, from the type in thickness or involution; butit seems to the writer equally objectionable to identify, e.g., a Yorkshire Pszloceras with an Alpine form only because their dimensions agree (for in both the erugatum and the calliphyllum species-groups similar variations would probably have occurred), or, as Hyatt has done, identify an Amzoceras from Peru with 4. ceras, Giebel, sp., when there is such a distinct change in the Amoceras fauna even from Gloucestershire to Dorset on the one hand and to Yorkshire on the other. It is known from the study of living mollusca that in the sea each locality gives its 1 “Etude sur les Mollusques et Brachiopodes de l’Oxfordien Supér. et Moyen du Jura Bernois,’’ Supplément I: Mém. Soc. Pal. Suisse, vol. xxviii, pp. 20-2, 1901. L. F. Spath—Notes on Ammonites. 173 inhabitants its own peculiar stamp; but when an Ammonite is described as, e.g., Phylloceras mediterraneum (Neumayr) race indica, Lemoine, or as Protogrammoceras cornacaldense(Tausch) var. zeugitanum, Spath, it is not certain that it really represents a horizontal variant or race, and not a vertical mutation. In fact, these terms can rarely be safely employed, and an attempt to trace the mutations of, e.g., Quenstedtoceras through R. Douvillé’s beds H, to Hg shows the unsatisfactory and difficult nature of their use. But on the examination of many hundreds of specimens of a variable species such as Hystrichoceras varians (Sowerby), Cardioceras cordatum (Sowerby), or Xipheroceras planicosta (Sowerby) (out of one block or bed, and, therefore, apparently contemporaneous) and as an alternative to using the term ‘‘variety’’ or creating new names, the use of the trinomial nomenclature suggests itself for these thick and thin, involute or evolute, weakly or strongly ornamented variations, as employed by, e.g., Solger for Hoplitoides ingens nodifer, H. ingens costatus, and H. ingens levis. Wepfer! also reintroduces Quenstedt’s trinomial nomenclature, but in a different sense. The genetic relationship between the Bajocian swbradiata-group and the Tithonian lingulati is too uncertain to include them all in the genus Oppelia, and, moreover, even such names as Glochiceras lingulatus carschtheis, Gl. lingulatus levis, and Gl. lingulatus crenosus, covering forms from different facies and different horizons between the bzmammatum zone and the Tithonian, would not be admissible. What has been said with regard to the form and coiling applies also to the use of the ornamentation of the shell for classificatory purposes. Von Buch’s sections with a keeled or grooved venter, or Mojsisovics’s divisions of Liostraca and Trachyostraca, were soon found to be unnatural groupings. ‘‘ Aegoceras”’ sagittarium, Blake, is an Asteroceras, though it hasno keel; ‘‘ Oxynoticeras” Greenought (Sowerby) is a Schlotheimia though it has no ventral groove. An Argovian NMeumayriceras, e.g., may have a groove on the ventral region of the chambered portion which, generally with the beginning of the body-chamber, changes into a keel. This passes into an interrupted line of tubercles which, disappearing abruptly, may again give way to a groove. According to whether this groove or the dentation is more pronounced, there are several combinations; at the same time the sides are often conspicuously smooth and the body-chamber often becomes abnormal and depressed.?_ And all this in one andthe same form. Again, the presence of a hollow carina, though occasionally constant, and the thickness of the siphuncle—at one time considered a distinction between ‘‘ Harpoceras”’ and Oppelids— cannot be used for classificatory purposes. Mojsisovics had at first* considered all post-Triassic Ammonites, except WDPhylloceras and Lytoceras, to be descendants of the 1 “Die Gattung Oppelia im siiddeutschen Jura’’: Paleontographica, vol. lix, pp. 1-68, 1912. 2 Wepfer, op. cit., p. 17. 3 “Die Cephalop. d. Mediterr. Triasprovinz’’: Abh. k.k. Reichsanst., vol. x, 1882. 174 L. F. Spath—Notes on Ammonites. Trachyostraca. In his later work,! however, he assumed, con- formably to the general opinion, that the whole of the Jurassic and Cretaceous Ammonites issued, by branching, from the family of the Phylloceratidee, i.e. Liostraca. Steinmann,” on the other hand, still maintains a purely artificial classification into Trachyostraca, Hemiostraca, Liostraca, and Heterostraca. J. Boehm? also emphasizes that from the study of Kossmaticeras it was clear that the systematic division of Cephalopoda according to the mode of ornamentation was an artificial one, and that stress was to be laid above all on the ontogenetic development. But though unsuitable for general purposes, the ornamentation or carination may be of considerable value for the minor groupings of Ammonoids. The course of the radial line in certain Hildoceratids, the different types of costation in the Perisphinctids, an important classificatory character, and in the ribbed descendants of Psiloceras, the tendency to differentiate costation either on the venter (with first thickened and then interrupted ribs) or on the side (with eventual carination of the ventral area) separate the two important families of Schlotheimine and Arietide. In the former, the development that leads up to a grooved periphery (in the ontogeny of the later forms) is separated generically( as Waehneroceras) from the forms of the succeeding hemere that have a similar tendency to lead back from a grooved periphery to a rounded venter (Schlotheimia). The terms anagenesis and catagenesis are avoided by the writer not only because, for example, a smooth (so-called catagenetic) form may show elaboration of all its other characters, but also because he considers the smooth oxycones in many stocks to be specialized 1“ Die Ceph. d. Hallstitter Kalke’’: Abh. k.k. Reichsanst., vol. vi, 1873-93, 2 vols. 2 Hinfiihrung in die Palaeontologie, 2nd ed., 1907. 3 N. Jahrb. f. Miner., etc., ii, p. 463, 1912 (in review of Kilian & Reboul’s paper on certain neo- Cretaceous Ammonites). * The writer used this character in the subdivision of the Middle Liassic (Domerian) Hildoceratids (‘‘ On Jurassic Ammonites from Jebel Zaghuan’’: Q.J.G.S., vol. lxix, pp. 547-52, 1913) and separated the Flexiradiata from the rectiradiate forms that constitute the genus Seguwenziceras. The genus Proto- grammoceras was created for the former, and two divisions were recognized within that genus; but one of these, characterized by dionase in peripheral projection and’ including subanguliradiate and angulirursiradiate forms, is covered by the genus Fuciniceras created just prior to the publication of the writer’s paper. The genus Protogrammoceras will, therefore, have to be restricted to the forms of the first subdivision, including subfalciradiate and falciradiate forms (type ‘‘ Grammoceras’’ bassanii, Fucini, ‘‘ Apenn. Cenfr.,’’ pl. x, fig. 6, 1900). Apart from their Domerian age, both the Rursiradiata (Fuciniceras) and the Falciradiata (Protogrammoceras) are distinguished from the Toarcian Harpocerates by their combination of evolute whorls with a tendency to change the periphery from fastigate to carinatisulcate and back again to fastigate. The form described and figured in that paper as gen. nov. sp. nov.(?) (pl. lii, fig. 2, p. 556) belongs to the group of forms wrongly referred to Harpoceratoides by Haas, and the new genus Lioceratoides (type “* Tioceras (?)’’ Grecot, Fucini, ‘‘ Apenn. Centr.,’’ Pal. Ital., vol. vi, p. 65, pl. xi, fig. 4, 1900) is now proposed for this development, characterized by a type of costation very distinct from that of the other Domerian Hildoceratids. L. F. Spath—WNotes on Ammonites. 175 adaptations, corresponding to elaborately ornamented spherocones or uncoiled shells in other lineages. In the family Arietide, the hastening in development of one character of the whorl or its ornamentation faster than another, or the delaying of a feature, afford valuable indications of the beginning of diversity of lineages. During the acme of the group, certain Alpine forms of Coroniceras show a tendency to retard the development of the keel and to flatten the periphery, which tendency probably leads to the Microderocerates. Other Alpine Coroniceras-torms hasten the development of the keel and foreshadow the somewhat later Aetomoceras, which seems to be a corresponding development of the bituberculate Agassiceras. In the later genus, again, the tendency to omit the keel and -to continue the costation across the venter probably leads to Xipheroceras and thus starts the family Aegoceratide, from which the Jlicroderoceras development, mentioned above, would, obviously, have to be excluded. It will be seen that the tendency of a lineage to develop or specialize in a certain direction (adaptative in response to changes of environment or intrinsic and aiming at diversity) is here favoured as the basis of lineal independence and generic classification, as opposed to the morpho- logical method of grouping together forms that fit the generic diagnosis of the textbooks, or to the cyclical method which assumes that stocks should develop according to a given ‘‘cycle’’ and show periods of ‘‘anagenesis”’ and ‘‘ catagenesis”’. Suess,! when first venturing on the subdivision of Ammonites, thought the length of the body-chamber and the shape of the mouth- border characters of systematic value. The former generally depends _ on shape and coiling, and Buckman and Bather* have pointed out that in Stephanoceras the body-chamber ‘‘ varies in length from about half a whorl in the thick forms (the supposed females) to very nearly two whorls in the thin forms (the supposed males)”. As a specific distinction this character alone has been used by Pompeckj,* who described as Psiloceras brevicellatum an Ammonite that differs from P. planorbe only in having a shorter body-chamber, On the other hand, G. von Arthaber * bases what appears to the writer to be a very artificial classification of Triassic Ammonites into Microdoma and Macrodoma, on the length of the body-chamber. He also states that “much more important than generally assumed seems to be the con- vergence of forms”, but groups such heterochronous homceomorphs as Beloceras and Sageceras together. As regards the shape of the mouth-border, great variability is shown even in one genus, e.g., Phylloceras, as H. Douvillé® pointed out. Of course, it might be objected that this genus really ought to be subdivided into a number of genera, but Douvillé thinks even the ornament of the sides “‘ perhaps more important for classificatory ‘‘ Uber Ammoniten’’: Sitzungsber. d. Wiener Akad., vol. lii, p. 71, 1865. Nat. Sci., vol. iv, p. 428, 1894. 3 ** Beitr. z. einer Revis. d. Amm. d. Schwab. Jura,’’ 1893, pt. i (T). 4 «« Grundziige einer Systematik d. Triad. Amm.’’: Centralbl. f. Min., etc., 1912, p. 245. 5 ‘* Gérat. de la Craie’’: loc. cit., pp. 278-9. 1 2 176 L. F. Spath—Notes on Anvmonites. purposes than the shape of the aperture”. The presence or absence of lateral lappets at the mouth-border is used for classification by Mascki,! who put Parkinsonia and Strenoceras into the family Otoitide, Baculatoceras into Stemmatoceratide, Garantiana and Sub- parkinsonia into Stephanoceratide. But Wetzel* has found ‘‘ ears” in a small form of Garantiana and only very slight lateral processes in larger forms, and he thinks that probably—as is the case also in Parkinsonva—in certain series the ‘‘ears’” disappeared with age, earlier in some series and later in others. Again, in Hecticoceras, Glochiceras, and other Oppelids “ears” are often confined to the younger stages, ‘‘ vary in form and size from one specimen to another, and show by this alone an impress of individuality that seems to deny them any usefulness for systematic purposes.’ When Waagen,in 1871, combined the Ammonitid genera in eight groups, he attributed “great importance to the presence or absence of the shell-plates termed Aptychus and Anaptychus, and to the particular structure of these remains”. Wright® also expressed the opinion that ‘‘the Aptychus played an important part in the organic functions of this large extinct group of tetrabranchiate Cephalopods”’. Butit had been shown long before that, in the case of Gastropods, as the operculum sometimes varies in structure in species of the same genus, as it is present in some volutes, cones, mitres, and olives, and absent in other species of these genera, and as some genera in a natural family, as Harpa and Dolium among the Buccinoids are without an operculum, whilst the other genera of the same family possess that appendage, it obviously affords characters of very secondary importance.6 H. Douvillé’ thought that “there was nothing to show that in one and the same family one might not find Aptychi of the same form that could have been either horny or else more or less impregnated with calcareous matter, the former would have disappeared during fossilization, at least in the majority of cases, whereas the latter would be preserved. The absence of the . Aptychus might, therefore, be only apparent, and it was a character of little importance”. The assumption that the operculum of Cephalopods has a greater systematic value than that of Gastropods, even if not homologous, is not justified. Apart from this our scanty knowledge of Aptycht found together with their parent Ammonites has proved a great practical difficulty, and Waagen’s classification was, from this point of view, unsuccessful. Mr. Crick*® thought that the traces of muscular attachment of the 1 “Die Stephanoceras-Verwandten der Coronatenschichten von Nord- deutschl.’’: Dissertat., Gottingen, 1907. 2 “Beitr. z. Pal. u. Stratigr. d. nordwestdeutschen Jura, ii, Faunistische u. stratigr. Untersuch. d. Parkimsoni-Schichten d. Teutoburger Waldes bei Bichfeld ’’: Paleeontographica, vol. lviii, p. 159, 1911. 3 Wepfer, op. cit., p. 40. * Zittel, History of Geology and Paleontology, English trans., 1901, p. 403. > Op. cit., 1880, p. 176. ® R. Owen, Lectures on the Comparative Anatomy and Physiology of the Invertebrate Animals, 1843, p. 296. 7 “* Cérat. de la Craie’’: loc. cit., p. 278. 8 **On the Muscular Attachment of the Animal to its Shell in some Fossil Cephalopoda (Ammonoidea)’’: Trans. Linn. Soc., vol. vii, pt. iv, p. 109, 1898. L. F, Spath—Notes on Ammonites. 177 Ammonoid animal to its shell afforded important characters for the purposes of classification, but both on account of the comparative scarcity and the indefinite nature of these impressions they have not proved of value yet in the classification of Ammonites. On the whole, then, the Ammonoid suture-line may be considered to be a more useful feature for classificatory purposes, especially of the larger groups and families, than any of the above characters, though, like any other character, it cannot be used by itself as the sole basis for the natural classification of organisms that are made up of an almost infinite number of characters, each of which is in a con- tinuous state of movement, either originative, progressive, or retrogressive.' Holzapfel? stated long ago that one single character, such as the shape of the first suture, the direction of the siphonal funnel, or the shape of the peristome, cannot well be used for classification. In his paper on the genus Oppelia* Wepfer stated : ‘In paleontological works the question is often asked, which characters in Ammonites are decisive, the lobes, the length of the body-chamber, etc.,etc.? I believe they all are, to a certain extent’ but one cannot formulate general rules. All characters are liable to variation, and what decides is the general appearance, at any rate we get further with this than with following some one-sided character.”’ Hyatt’s classification of the Nautiloids * according to the structure of the septal neck, though more attractive than the previously existing classifications, cannot be really natural, and when it is found that Hyatt® included, e.g., in his family Estonioceratide, based on the shape of the whorls, beside the Ordovician genus Hstonvoceras, also the Jurassic Digonioceras, that is two genera that almost certainly have not the remotest affinity, the artificial character of his classification becomes evident. ‘The same apples to his classification of Ammonoidea, as is shown, by the inclusion in, e.g., his Leptocampyli of such a heterogeneous mixture of Ammonoids belonging to widely removed stocks, or his separation of such closely allied genera as, e.¢., Reimecketa and EHrymnoceras, Sigaloceras and Kepplerites, not only into different families, but even different super-families. It seems to the writer that the development of the Ammonite suture-line has to be studied from its first“‘angustisellate”’ beginning, and used as a basis for classification only in conjunction with the development of all the other characters of the shell. The use for general classification of, e.g., the symmetrical or asymmetrical arrangement of the first lateral lobe, the changing width of the external saddle, the number of auxiliary lobes, or any other similar peculiarity of the suture-line, by itself, is unsatisfactory. 1 H. F. Osborn, ‘‘ Origin of Single Characters as observed in Fossil and Living Animals’’: Presidential Address Pal. Soc. Amer., 1914 (see Nature, November 11, 1915, pp. 284-5). 2 “*Die Cephalopoden-fiihrenden Kalke d. Unt. Carbon v. Erdbach- Breitscheid bei Herborn’’: Pal. Abh. v. Dames u. Kayser, vol. v, No. 1. > Loe. cit., 1912, p. 30. * The Genera of Cephalopods, ete., 1883. ° In Zittel-Eastman, op. cit., 1900. DECADE VI.—VOL. VI.—NO. IV. 12 178 Some Recent American Petrological Literature. V.—Some Recent AMERICAN PeErRonocicaL LITERATURE. (Continued from p. 128.) ‘“« Structure of the Anorthosite Body in the Adirondacks,” by H. P. Cushing. Journ. Geol., vol. xxv, pp. 501-8, 1917. A criticism of Dr. Bowen’s conclusions as to the field relations of the different rock-types of the area. ‘‘ Adirondack Intrusives,” by N. L. Bowen. Ibid., pp. 509-12, and H. P. Cushing, ibid., pp. 512-14. A continuation of the discussion on the two preceding papers. “The Relation of the Titaniferous Magnetite Ores of Glamorgan Township, Haliburton County, Ontario, to the Associated Scapolitic Gabbros,” by W. G. Foye. Econ. Geol., vol. xi, pp. 662-80, 1916. It is concluded that gases given off by the acid and intermediate magmas collected beneath the gabbro, oxidizing itsiron to titaniferous magnetite and depositing this below the Jaccolith; the chlorine and other gases thus set free scapolitized and recrystallized the overlying gabbro. “‘The Relation of the Titaniferous Magnetites of North-Eastern Minnesota to the Duluth Gabbro,” by T. M. Broderick. Econ. Geol., vol. xii, pp. 663-96, 1917. The gabbro has developed magnetite-bearing rocks along its contact with the Gunflint iron formation, including coarse-textured fayalite-pyroxene-magnetite rocks, hitherto mistaken for marginal facies of the gabbro. Several types of magnetic ores within the gabbro are partly magmatic segregations and partly inclusions of the Gunflint formation. ‘The Geology of Pigeon Point, Minnesota,” by R. A. Daly. Amer. — Journ. Sci., vol. xliii, pp. 423-48/ 1917. A re-examination of the occurrence of micropegmatite (red rock) in a basic intrusion. The intrusion is considered to be a sill, not a dyke, as supposed by Bayley, and the variation in composition is due to differentiation, mainly by gas-action, after stoping and assimilation of Animikie quartzite. ‘‘ Petrography of the Pacific Islands,” by R. A. Daly. Bull. Geol. Soc. Amer., vol. xxvii, p. 325, 1916. The available data lead to the conclusion that the primary Pacifie magma is basaltic and that andesites and ultrabasic lavas have been differentiated from this: certain alkaline types may be limestone syntectics. ‘A Contribution to the Petrography of the South Sea Islands,” by J. P. Iddings and E. W. Morley. Proc. Nat. Acad. Sci., vol. iv,. pp. 110-17, 1918. Analyses are given of rocks from Tahiti and other islands of the Georgian and Society groups, many of which are profoundly eroded volcanoes, consisting mainly of basalts rich in augite and Some Recent American Petrological Literatwie. 179 olivine, with little felspar: at five of them are late trachytic and phonolitic lavas, while two show coarsely crystalline cores of gabbro or theralite and in one case syenite and nepheline-syenite. ‘© Age of the Igneous Rocks of the Adirondack Region,” by A. P. Cushing. Amer. Journ. Sci., vol. xxxix, pp. 288-94, 1915. The orthogneisses which have been metamorphosed along with the Grenville rocks have been invaded by the anorthosite-syenite group, which contain inclusions of the gneisses. It is held that the orthogneisses and the anorthosite-syenite group are distinct and should not be classed together. ‘The Composition of the Average Igneous Rock,” by A. Knopf. Journ. Geol., vol. xxiv, pp. 620-2, 1916. Using the data given in Daly’s Jgneous Rocks and their Origins, the writer calculates a new average igneous rock, taking into account the actual volume of each type, so far as known. This average is found to agree very closely with that previously given by Clarke. “The Summation of Chemical Analyses of Igneous Rocks,” by H. H. Robinson. Amer. Journ. Sci., vol. xli, pp. 257-75, 1916. An application of the laws of probability to the determination of errors of summation, as a guide to the quality of the analytical work. *‘Use of the Slide-Rule in the Computation of Rock Analyses,” by J. H. Hance. Journ. Geol., vol. xxiii, pp. 560-8, 1915. The author gives two tables of the percentage composition of rock- forming and ore minerals with a method of use applicable to an ordinary slide-rule for the conversion of analyses into the corresponding mineral compositions. ‘‘Suggestions for a Quantitative Mineralogical Classification of Igneous Rocks,” by A. Johansen. Journ. Geol., vol. xxv, pp. 63-97, 1917. The basis of the proposed elecsiteation is a figure in the form of a double tetrahedron, each corner representing certain mineral constituents of the rock, the composition of any type being repre- sented graphically in its proper position in the figure. The minerals are divided into groups and a large number of new rock-names are proposed. “‘Types of Prismatic Structure in Igneous Rocks,” by R. B. Sosman. Journ. Geol., vol. xxiv, pp. 215-34, 1916. Several types of prismatic structure are distinguished as due to thermal contraction, convection in the still lquid magma, and internal expansion respectively. “The Microscopical Characters of Voleanic Tuffs, a Study for _ Students,” by L. V. Pirsson. Amer. Journ. Sci., vol. xl, pp. 191-211, 191 . A discussion of the origin and characteristic structures of tuffs, with a description of the criteria for their recognition when altered, weathered, and metamorphosed. 180 Reviews—Gastropoda, Upper Cretaceous of Tennessee. RAV LEwvs.- I.—New AND LITTLE-KNowN GasrropopA FRoM THE Upprr Cre- Tackous OF ‘TENNESSEE. By Bruck Wapr. Proc. Acad. Nat. Sci. Philadelphia, vol. lxix, pt. 11, pp. 280-304, pls, xvii—xix, 1917. E have referred in a previous issue (Gon. Mag., 1917, p. 471) to the notable results of Dr. Bruce Wade’s study of the. Gastropod fauna from the Upper Cretaceous Ripley formation of Coon Creek, in McNairy County, Tennessee. The fossils from this locality are in a remarkable state of preservation, and consequently afford excellent material as a basis for the establishment of new generic. types. We have now before us a second contribution, in which further new forms are established. Among them is Conorbis menairyensis, a new species founded on a single specimen, which is the only member of the Conide in the fauna. This record is important on account of its being the first typical representative of the genus in the Upper Cretaceous; it shows all the salient features exhibited by Sowerby’s Conus dormitor, the type of the genus Conorbis, from the Eocene of Western Europe. Three new genera in the Volutide are established, and a new species is assigned to Grabau’s Valsifusus and to Conrad’s Linosoma, also of this family. Myllus is a genus (type, H. callilateras, n.sp.) of large, unornamented volutes, with expanded bodies and low spires. The characteristics of this genus resemble those of Lvopeplum, but there are differences in the form of the spire and the disposition of the columellar plaits. The new genus Boltenella (type, B. excellans, n.sp.) includes a group of well-defined forms of fulguroid shells, with large paucispiral protoconchs and subdued ornamentation, probably intermediate between the Busyconide and the Fuside. Scobina is a generic name given to a number of shells similar in general shape to Hercorhynchus. The strongly inflated body resembles Conrad’s Rapa cancellata from the Cretaceous of India, but in the new genus there is a marked increase with age in the spiral angle. 8S. dicarinata, n.sp., is the genotype. The new species assigned to the genus Valsifusus, #. mesozoicus, is a fragile, slender shell, marked by spinose terminations of the axials along the shoulder angle. This form and Kaunhowen’s Fusus bicinctus are the first two species from the Upper Cretaceous to be referred to Falsifusus. In another genus, Lirosoma, a new species (eretacea) is again recorded for the first time from the Cretaceous. This form resembles the generic type from the American Miocene. The Buccinide are represented by one new genus, Seminola (type, S. crassa, n.sp.), named after a tribe of Indians who formerly in- habited the south-eastern coastal plain. The genus resembles Meek’s Odontobasis, of which the fusiform outline distinguishes it from the globose form of Seminola. An elegant little pyriform shell, with a depressed spire, Kephora proquadricostata, u.sp., has again the interest of being the first representative in the Cretaceous of a genus well known in the Upper Tertiary of the Atlantic Coast district. Belonging to the same Reviews—Indian Geology and Physical Geography. 181 family, the Purpuride, is a new genus, Paramorea (type, P. lirata, n.sp.), which can be distinguished from Jorea by the presence of a narrow, oblique chink instead of a well-defined umbilicus, by an acute spire, and by the absence of the strongly reflected inner lip. Two genera new to the Cerithiide are also established. Wudivagus (type, IV. simplicus, n.sp.) includes a group of simple, elongately conical shells, with no external’ornament. ‘To this genus, more- over, Stoliczka’s Indian Cretaceous Cerithium (Fibula?) detectum and Hudleston’s Pseudomelania astonensis, from the Inferior Oolite of England, are also referred. Astandes (type, -A. densatus, n.sp.), a small trochoid shell, resembles Conrad’s Cerithioderma in outline, but its spire is less acuminate and the umbilicus imperforate. By its short anterior canal, also, it can be distinguished from Gardner's Paladmete, which otherwise it resembles. Included in this new genus is Holzapfel’s Zritoniwm cretaceum, from the Aachen Cre- taceous. Acirsa and Hemiacersa belong to the Scalide; of the former two new species are described and one of the latter. The form named Chemnitsia cerithiformis by Meek and Worthen is now considered to be an Acirsa, and Kaunhowen’s Maestrichtian Scalaria dense- striata is probably comparable with A. corrugata, n.sp. De Boury’s Hemiacersa is enlarged by the inclusion of H. cretacea, n.sp., of which the single example is notable on account of its being the first recorded from the Upper Cretaceous. The present contribution to the systematic study of this fauna ends with the establishment of the new genus Creonella, belonging to the Pyramidellide. The genotype, C. triplicata, n.sp., is a small, slender, conical shell, like Pyramidella, and is characterized by three conspicuous folds on the inner lip. We await with interest the results of Dr. Bruce Wade’s further studies on this fauna. Cy Pc: IJ.—A Brsriograprny or Inptan GrEoLocy AND PuysicaL GEOGRAPHY, with an AnnotaTeD InpEx oF Minerats or Economic VALUE. Compiled by T. H. D. La Toucusz, M.A., F.G.S., F.A.S., Bengal. Published by Order of the Government of India, and printed in Caleutta for the Geological Survey of India. London: Kegan Paul & Co. Imp. 8vo. Part I (1917), pp. xxvii + 571, price 5s. 4d.; Part II (1918), pp. 490, price 6s. HE author of this important work is a man well qualified for the task, having served for thirty years upon the staff of the Geological Survey of India, to the ‘‘ Records’’ of which he was himself a frequent contributor. During his long service he was a careful and diligent compiler of references bearing upon both geology and physical geography and on the mineral resources of India. He had also the advantage of being able to make use of Mr. R. D. Oldham’s very complete bibliography, presented to the Geological Survey of India in 1888. The earlier additions made by the author to Mr. Oldham’s work have been largely due to his long English residence 182 1. Reviews—A Mystery Crinord. in Cambridge, by which he had access to the libraries of the Cambridge University, the Geological Society of London, the India Office, the British Museum, the Imperial Institute, the Science Museum, the Royal’ Geographical Society, and the Institute of Civil Engineers. Thanks are also recorded by the author for assistance given him by many State Geologists who have aided in his work. - The first volume (dated 1917) is devoted to a Bibliography of Indian Geology and Physical Geography, under authors’ names, prefaced by 23 pages of abbreviated titles used in the work (all alphabetically arranged). The second volume (dated 1918) contains an ‘‘ Annotated Index of Minerals of Economic Value’; this is intended to be used in conjunction with the bibliography (which, indeed, is included and really forms part of this work). The: figures inserted in brackets after the observer's name correspond to the serial number allotted to each author, followed by the number of the page on which the reference will be found. A list: of works dealing generally with the distribution of economic minerals in India is given under provinces and authors, for India, Burma, Madras, Punjab, and Rajputana, the names of minerals being arranged alphabetically: e.g. Alum, Amber, Chromite, Coal, Copper ore, Corundum, Diamonds, etc., so that no separate index is required. Much information relating to the mineral resources of the country collected within recent years is stored up in the progress reports and correspondence files of the Geological Survey Department in Calcutta, where it may be studied by those who are interested in the subject, either in its scientific or commercial aspects. The matter comprised under the general heading ‘‘ Building Materials” (pp. 27-62) is of course very complex in its nature, embracing descriptions and localities for limestones, sandstones, slates, quartzites, granites, marbles, basalts, gneissic rocks, laterites, serpentinous limestones, dolomites, etc., in great variety. By this valuable compilation Mr. T. la Touche has conferred a great service on all who are seeking information on Indian geology. He has given us in these volumes a ready reference to the authors of all books and papers, not only relating to the geology and physical geography of our Indian Empire, but also to its economic minerals and rocks and the localities in which they are found. It is a book which should find a place in the reference works of every scientific library, but is much too large to carry in one’s handbag. i IJI.—A Mystery Crrivoip. On Mysricocrinus, A NEW GENUS OF SituRIAN CrinomipEA. By Frank Springer. Amer. Journ. Sci., xlvi, pp. 666-668, pl. ii, Noy. 1918. (JHE genotype is Mysticocrinus wilsont, of which the holotype and -afragment were obtained by Dr. Herrick E. Wilson from the Laurel formation near St. Paul, Indiana, and are in the Springer Collection at the U.S. National Museum. The crown, with stumpy infolded: arms, is like a wrinkled pea in size and shape. The cup Reviews—Geological Structure of Vale of Kingsclere, 188 consists of 3 unequal infrabasals (the small one right posterior), 5 basals, 5 radials, a radianal (forming the lower part of r. post R.), and a long anal w. This last rises in a spearhead between the adjacent arms; the other arms are separated by similar spearheads, formed from both shoulders of the anterior radial and the right and left shoulders of the right and left posterior radials; the antero- lateral radials have no such processes. The arms consist of 2 primibrachs followed by equal rami of 3 secundibrachs, except in the antero-lateral rays, which have but one primibrach. The tumid cup- plates and the short square brachials of the short arms give the crown a massive appearance, despite its small size. Dr. Springer assigns this new genus to no Family, and is, indeed, uncertain as to the Order, though describing it as a Dicyclic Inadunate “intermediate between the Larviforma and the Fistulata’”’. If by © this he means phylogenetically intermediate, he is deriving dicyclic forms from monocyclic, which is unjustified. He excludes it from the Flexibilia because there is ‘‘no indication of loose suture or flexibility in cup or tegmen”’. None the less Mystrcocrinus would seem better placed in that Order. The tegmen in any case is unknown, and in so small a cup it would be hard to see any indica- tions of loose suture. ‘The anal z recalls that of Lecanocrinus, as Dr. Springer says, also that of Anisocrinus. The tightly-closed arms resemble those of Lecanocrinus and still more those of Mespilocrinus. The inadunate character of the arms is primitive and is paralleled by Pycnosaccus, which has wide interbrachial areas occupied by small irregular plates. That genus and. JLecanocrinus also display a tendency to have a single primibrach instead of the two usual in the early Flexibilia. The primitive position of the radianal is retained also in the Silurian Flexibilia, Clidochirus and Ichthyocrinus. When Dr. Springer’s great Monograph of the Flexibilia reaches this country we shall see to which of his Families Mysticocrinus might be referred. Its ‘‘ mysterious” characters are due partly to its primitive stage of development and partly to conditions, probably of a reef-like nature, such as have so often produced similar forms. KF. A. Barner. ITV.—Nores on tHe GroLtocicaL SrRvucrurE oF THE VALE oF Kines- cLERE. By H. L. Hawkins. Proc. Hampshire Field Club, vol. vill, pp. 191-212, with 4 plates, 1918. (J\HE author gives an interesting sketch of the stratigraphy of the Vale of Kingsclere, with a general account of the development of the Cretaceous and Tertiary deposits. Asa result of his paleonto- logical work in the Upper Chalk, he proposes to subdivide the coranguinum zone, which is of unwieldy proportions, by marking off the upper portion as the ‘‘sub-zone of Conulus albogalerus’’. Some modifications are also suggested in the reading of two well-sections, affecting the assignment of certain beds to the London Clay and Reading Beds respectively. The most important part of the paper. however, is concerned with the tectonics of the district.. A detailed 184 | Reviews—Geological Observations in F112. study of the strike of the strata indicates that the periclinal structure of the district is modified by the interference of two anticlines and a syneline having a N.N.W.-8.S.E. strike and parallel to the East London ridge. These folds, though of very slight amplitude, never- theless produce a marked effect on the strike of the Cretaceous rocks and are possibly due to slight posthumous movements of the Charnian fold-series. Hence it is possible that Paleozoic rocks may underlie the district at no great depth. V.—GrotocicaL Osservations In Frizz. By W. G. Forx. Proc. Amer. Acad. Arts and Sci., vol. liv, pp. 1-145, with 1 plate and 40 figs., 1918. ROFESSOR FOYE spent seven or eight months of 1915-16 in a geological expedition to the islands of the Fiji group, chiefly for the purpose of studying coral-reefs at first hand, and this long paper gives an account of his observations and the conclusions drawn from them. ‘The first part, entitled ‘‘ Geological History of Fiji”, describes the physiography and stratigraphy of the islands, and discusses the living and raised reefs in considerable detail. The larger islands possess a plutonic core and two series of sedimentary rocks, the older, probably Miocene, being folded along trend-lines parallel to those described by Suess in other parts of Oceania, the younger unfolded and apparently post-Tertiary. Four separate voleanic phases are recognized with a regular gradation in acidity, namely, (1) rhyolite, (2) andesite, (3) andesite, (4) basalt. The elevated limestones rest unconformably on eroded volcanic rocks, and there is abundant evidence of great instability of relative level throughout the group, partly due to uplift and subsidence and partly to return of water after the Glacial period. Hence the conditions are very favourable to the formation of reefs according to Darwin’s theory. The reduction of masses of elevated limestone to sea-level has in some cases been accomplished by atmospheric solution, and slight submergence initiates the growth of reefs and atolls on these platforms. The present coral-reefs have been developed on surfaces formed by integration of a number of pro- cesses: (@) atmospheric erosion, (6) wave-cutting, (c) sedimentation, and (d) voleanic aggradation. On the other hand, it is demonstrated that the older limestones developed on a subsiding basement of eroded volanic rocks, but no evidence could be found in Fiji for the existence of Pleistocene benches; the platforms are much more modern in their development. The second part of the paper gives a petrographic description of the rocks collected, including plutonic, hypabyssal, voleanic, pyro- clastic, and sedimentary types. The igneous rocks are exclusively Pacific in their character, the most acid rock observed, with 70 per cent of SiOz, called tonalite by the author, being composed of quartz, plagioclase, biotite, and hornblende. This appears to grade into diorite and gabbro, while the volcanic rocks are characterized by hornblende, augite, and hypersthene. It is suggested that the horn- blende-hypersthene rocks have been formed by submarine eruption, Reviews—Asbestos in the Union of South Africa, 185 the retention of gases allowing these minerals to form, whereas subaerial eruptions without water gave rise to augite. ‘The voleanic vents of the region appear to have been extremely persistent in their localization, since the later basalts came from the same craters as the andesites. This paper must be regarded as a valuable contribution to the ever-growing American literature of the reef-problem and of the petrography of the Pacific Islands. VI.—Assestos In THE Unton or Sourm Arxica. By A. L. Hatt. Geological Survey of the Union of South Africa, Memoir No. 12. pp- 152, with 15 plates, 16 text-figures, and a map. Pretoria, 1918. Price 5s. | F late years the Union of South Africa has become an important producer of asbestiform minerals for the world’s market. It possesses deposits of chrysotile, tremolite, and crocidolite, and a new and important variety, here called amosite, has recently been developed on a commercial scale in the Transvaal. In this memoir Mr. Hall gives a full account of the properties and occurrence of all these varieties. Chrysotile is found in workable quantities in the Carolina district of the Transvaal in the upper part of the Dolomite Series, a few feet above a large basic sill. It also occurs in the Tugela Valley in Natal, as described by Dr. Hatch in 1910. Crocidolite is found in very large quantities in the banded ironstones of the Lower Griqua Town Series, which are equivalent to the lower part of the Pretoria Series of the Transvaal. Amosite is an amphi- bole, rich in ferrous iron and pale grey or nearly white in colour, and remarkable for the great length of its fibres, which can be obtained in quantity averaging 6 inches. It is found in the Lydenburg and Pietersburg districts of the Transvaal, near the base of the Pretoria Series. The genesis of crocidolite and amosite is discussed in detail and attributed to metamorphism of ferruginous and siliceous sediments associated with rocks containing magnesia and soda. ‘The origin of the amosite deposits is believed to be connected with the intrusion of the Bushveld complex. The industrial aspects of the subject are also dealt with. VII.—Ow Sxcrrons In THE Lower Permian Rocks at CLAXHEUGH and Down Hitt, Co. Dunnam. By Davin Wooracort, D.S8c., F.G.S. Trans. Nat. Hist. Soc., Northumberland, Durham, etc., w.s., vol. v, pp. 155-162, with 4 plates and 2 figures, 1918. fW\HE author discusses the various ways in which brecciation has been produced in the Permian rocks and describes sections showing that local disturbances have been produced by horizontal movements due to thrusting from west to east, by which part of the Marl Slate and Lower Limestone have been displaced and cut out. No suggestions are offered as to the cause of the thrusting, but reference is made to the work of Trechmann on deposits of anhydrite at Hartlepool and to the presence of sulphates in the Permian rocks of other parts of North-East England. It is suggested that the 186 Reports & Proceedings—Geological Society of London. removal of these by solution would at any rate lead to an accentuation of the effects of such movements, if produced by other agents. VIIJI.—Summary Report or tHe Mines BrancH oF THE DEPARTMENT or Mines, Canapa, FoR THE YEAR 1917. 158 pp., with 4 figures. Ottawa, 1918. Price 15 cents. ee publication contains a summary of the work of the various divisions of the Mines Branch and gives evidence of great activity in several directions. Among the work of properly geo- logical character may be mentioned reports on the iron-ores of the Rainy River district, on the limestones of Ontario, and on certain sands and sandstones. The Fuels and Fuel-testing Division in- vestigated a large number of peat bogs in various localities, while the Ore-Dressing and Metallurgical Division carried out tests on a large number of ore samples, including gold, silver-lead, iron, manganese, chromite, tungsten, and molybdenum. The Ceramic Division examined into resources of clay and shale in several provinces, and an account is given of the manufacture of magnesite products, an industry of growing importance. REPORTS AND PROCHEDINGS. I.—Grotoetcat Socrery or Lonpon. February 5, 1919.—Mr. G: W. Lamplugh, F.R.S., President, in | the Chair. The following communication was read— ‘The Geology of the Marble Delta, Natal.” By Alexander Logie Du Toit, B.A., D.Sc., F.G.S8. The paper deals with the crystalline dolomitic marbles of Port Shepstone, Natal—rocks that have already been the subject of several communications to the Society ; but its main object is to demonstrate that certain ‘‘ boulders” of alkali-granite, formerly regarded as inclusions, are in reality parts of intrusive tongues, and to discuss the mutual relations of the igneous rocks and the adjacent dolomites. The main area of Marbles covers a tract of about eight square miles. It is not a solid block surrounded by granite and gneiss, but a bent and twisted mass enveloped and underlain by igneous material, and cut into several distinct portions by great intrusive sheets. The Marbles, almost wholly dolomitic in composition, are medium to coarse-grained rocks that have their bedding-planes marked out by various contact-minerals. They reach a total thickness of about 2,000 feet, and are divided into an upper and a lower portion by a narrow belt of quartz-schist. The plutonic rocks are, for the greater part, coarse-grained biotite- or hornblende-orthogneisses, with streaks and belts of hornblendic gneisses, schists, and granulites at or near the contacts with the Marbles. A conspicuous feature of the igneous rocks is that, for a distance of two to eight miles from the contact, they contain red and brown garnets. Reports & Proceedings—Liverpool Geological Society. 187 _ In addition to the normal type of metamorphism produced by the gneiss and the granitic offshoots therefrom, there is also developed at the contacts a phase almost identical with that presented by xenoliths of limestone in volcanic rocks. Through the action of magmatic emanations, zones possessing more or less regularity have been pro- duced in the adjacent dolomitic marble, of which the innermost is commonly rich in diopside and often in scapolite, with forsterite, phlogopite, chondrodite, and spinel farther away. ‘The dedolomitiza- tion is usually perfect. In the contact-zone forsterite and chondrodite are antipathetic minerals, the latter being invariably farther removed from the intrusion. In certain cases the marble beyond the silicate-zone has been deprived of the bulk of its magnesia, and has been changed into a mass of coarsely crystalline calcite. ‘his phenomenon has probably been due to the action of carbonated waters during the cooling of the plutonic masses. The absorption of marble by the magma at the contacts has caused the development of pyroxene in the intrusive rock, but there is no evidence in this area of large-scale assimilation of marble by the gneiss. I1.—Liverpoon Gnoxoeicat Sociery. | February 11, 1919.—W. A. Whitehead, Esq., B.Sc., in the Chair. The following papers were read :— 1. “ The Ancient Settlements in Wirral in relation to the Surface Geology.” By William Hewitt, B.Sc. A study of the geological drift map of the Wirral peninsula in relation to the early settlements in the area revealed certain points of interest. For the purpose of the inquiry the peninsula was considered as extending beyond the existing boundaries of the “hundred of Wirral” to a line running from the River Dee at Chester to the opening of the River Weaver into the Estuary of the Mersey. Of the surface so defined, approximately 643 per cent is covered with boulder-clay and 13 per cent with drift sand; 19 per cent is made up of various patches of Triassic rocks free from glacial deposits, while the remaining 15 per cent is covered with recent deposits. The 77 ancient settlements in the area which are either mentioned directly in the Domesday Survey Record (viz. 52) or are known from early records to have been in existence at the time of the Conquest, are situated as follows: 41 or 53 per cent on exposed rock surfaces free from drift, 2 on blown sand, 10 on drift sand, and 24 or 31 per cent on boulder-clay, this distribution showing a marked preference for a pervious foundation. A detailed classification of the settlements was given, and many particulars of interest both to the archeologist and to the geologist are recorded. 2. ‘Some Borings through the Marshes bordering the Southern Shore of the Mersey Estuary.” By F. T. Maidwell. In this paper full details are given of a large number of borings made in recent years by the firm of E. Timmins & Sons, Ltd., 188 Reports & Proceedings—Edinburgh Geological Society. Runcorn, in the neighbourhoods of Frodsham, Ince, and Ellesmere Port, some of which reached a depth of over 900 feet below the surface. At Ellesmere Port evidence has been obtained of an. important trough fault, and the thickness of the drift has been proved to be as much as 118 feet. None of the boreholes passed beyond the Lower Bunter Sandstone. I1].—Epinzurew Grorocicat Socrery. January 22, 1919. (Received February 14.)—Professor Jehu, President, in the Chair. 1. ‘‘The Origin of Terrestrial Vertebrates.” By the President, Professor T. J. Jehu. The ancestry of vertebrates is still an unsolved problem, and paleontology can throw little light on the subject. One theory traces their descent through a series of primitive Chordate forms represented by Amphioxus, the Tunicata, and Balanoglossus. The peculiar ciliated larva of Balanoglossus, known as Tornaria, shows marked resemblances to the larvee of the echinoderms, and a form similar to this larva may possibly have been the common ancestor of echinoderms and vertebrates. Another hypothesis derives the vertebrates from the Annelida, the organs of which show a curious correspondence, but with a general reversal of the relation of the various parts to one another. A recent theory seeks the vertebrate ancestor amongst the more primitive arachnoids, now represented by Limulus, and formerly exhibited by the extinct group of Merostomata. Chamberlin’s theory is that the vertebrates originated in flowing land waters as a response to the influence of strenuous dynamic conditions impressed upon a primitive animal aggregate towards the close of pre-Cambrian times. The return of migratory fishes to rivers for spawning purposes is an argument in favour of regarding flowin land waters as their ancestral home. Primitive armoured fishes are found in Ordovician sediments in Western America, and more typical fishes appeared in Europe towards the close of the Silurian period and became abundant in Old Red Sandstone times. The appearance of fishes which utilized the air-bladder for respiratory purposes at this period was the result of adaptations to oscillations of climate leading to alternate seasons of drought and rain. The life-habits of Dipnoans and fringe-finned Ganoids which have survived as relic fauna to the present day were described. These afford a clue to the conditions of life which, during Devonian time, led to lung-breathing in the Dipnoans and Ganoids of that period. Increasing aridity of climate eventually led to the emergence of vertebrates from their aquatic habitat and their adaptation to life on land... This transition is illustrated in the Amphibia which appeared at the close of the Devonian period and developed into diverse forms during the Carboniferous. The fact that the early life of amphibians is aquatic and that for a time they breathe by means of gills, shows that they were not completely adapted to a terrestrial life. The Stegocephalia show more resemblances to the fringe-finned Ganoids than to the Dipnoans, especially in the structure of the limbs, and more probably Reports & Proceedings—Ceologists’ Association. 189 evolved from that Order. At the beginning of the Permian the Stegocephalia gave rise to the reptiles which were able to survive more completely arid conditions and were adapted to an entirely terrestrial life. Reference was made to Broom’s theory that the evolution of mammals from reptiles was rendered possible when the Theromorphs developed limbs which enabled them to carry the body off the ground. The aridity of climate during Permian times served as an incentive to speed, and the extensive glaciation, which supervened during that period in the Southern hemisphere, favoured the acquisition of warm blood and of heat-retentive clothing. In their anatomical features the Theriodonts of the Permian and Triassic bridge the gap between reptiles and mammals. This was illustrated by a description of the origin of the paired occipital condyles of the mammal from the tripartite single condyle of Theromorphs, by the gradual reduction of the bony elements of each half of the lower jaw in these reptiles, by their heterodont dentition, by the structure of the shoulder and hip girdles and other features. 2. Specimens of native gold from Rhodesia were exhibited by Dr. M’Lintock. TV.—Gerotoeists’ Association The annual general meeting of the Geologists’ Association was held at University College, Gower Street, W.C. 1, on February 1, 1919, when the following lecture was delivered :-— “The Nimrud Crater in Turkish Armenia.” By Felix Oswald, D.Sc., F.G.S. The Nimrud volcano, situated on the west coast of Lake Van in Turkish Armenia, has a perfect crater nearly five miles in diameter. The precipices of the crater-wall rise two thousand feet abruptly from a deep lake which fills half the area of the crater. The lecturer described the external and internal features of this great volcano, which he visited and surveyed some years ago, and he gave a summary of its geological history down to its last eruption in 1441. The lecture was illustrated by lantern-slides, photographs and | drawings. Marchi, VIL: ‘‘Some Suggestions on the Flaking and Evolution of Flint Implements.” By 8. Hazzledine Warren, F.G.S. The paper dealt with the following points :— Characteristics of the fracture of flint under internal molecular strain, flexion, tension, compression, etc. The planes of least resistance—what they are and what they mean. The designed flake and the accidental chip. Normal flaking at about 75° tending to cuneiform flakes. High angle and low angle edge-flaking tending to incurved flakes. The Levallois-Pressigny method. ‘Suggested evolution of the Neolithic axe and double axe from special forms of paleoliths. Possible development of the Neolithic arrow-point, scraper, sickle-knife and certain other implements from the Mousterian racloir along divergent lines of evolution. The importance of wood and bone for implement making in past human industries. 190) Correspondence—J. B. Scrivenor. CORRESPON DEN CE. TOPAZ AS A ROCK CONSTITUENT. Sir,— When a paper on the Gunong Bakau topaz and cassiterite’ appeared in this Magazine for 1916, it was sufficient for the time being to ask you to publish a report? to which the author referred in order to show that before I worked out the structure of Gunong Bakau * he held the view that the quartz-topaz rock was ‘‘ topazised granite ’’, and attempted to explain the horizontality of one of the ore-bodies by faults, thrusts, and a landslip, although in his paper he writes of the ‘important veins intrusive in the porphyritic granite”, and argues that because certain topaz-bearing rocks in Germany and elsewhere are considered to be altered granitic rocks, the same origin should be accepted for the Gunong Bakau quartz- topaz rock. I do not propose to repeat the evidence on which my opinion that the topaz is a primary mineral was based, but there are two points of general interest that might be mentioned in connexion with topaz as a rock constituent. On pp. 300 and 301 of Lhe Natural History of Igneous Rocks Dr. A. Harker writes: ‘‘Closely bound up with the greisens are the tinstone veins, the cassiterite probably resulting from reaction between the volatile tin fluoride (SnF,) and water. The destructive action of fluorides is exceedingly energetic. At Geyer, in Saxony, granite is locally converted to a rock containing more than 90 per cent of topaz,’’ and quotes as his authority regarding the Geyer rock Salomon & His’ paper in the Zeit. deutsch. geol. Gesellschaft, vol. xl, pp. 570-4, 1888. Dr. Jones follows Dr. Harker in making a similar reference to these authors; but the fact remains that whatever may be the truth about the origin of the topaz they described, Salomon & His did not write anything in that paper that justifies their being quoted as authorities for its formation by the destructive action of fluorides. On the contrary, Salomon and His made it clear that they considered the topaz in the greisen to be the primary topaz that occurs in the granite. They mentioned topaz as being widely distributed as a constituent of the granite stocks, although it seldom becomes a prominent constituent. They said that one must expect the topaz, so characteristic of the granite, in the greisen as well, and on pp. 573 and 574 they described ageregates of topaz with a little felspar and mica which become converted by decomposition into aggregates of 90 per cent topaz with a little kaolin and ferrite. ‘Sead ime to these authors the topaz was not formed by pneumatolysis. Never having seen the Geyer or indeed any German greisens in the field, I am not in a position to say whether Salomon & His were correct in their view or the reverse. 1 Dr. W. R. Jones, ‘‘ The Origin of Topaz and Caxeticrite in Malaya ”’ GEOL. MAG., 1916, pp. 255-60. 2 Loe. cit., pp. 453-6. 3 Quart. Journ. Geol. Soc., vol. xx, pp. 363-81, 1914. Correspondence—F, R. C. Reed. LO On p. 379 of my paper on the Gunong Bakau rocks I pointed out that without segregation one could not expect to have a rock very rich in topaz. Ina pure orthoclase magma the 18°4 per cent of alumina could only produce 32°6 per cent of topaz if attacked by fluorine unaccompanied by more alumina. Dr. Jones produces evidence to show that alumina was introduced into some greisens.! I do not know how the rock-sampling was carried out in the cases quoted, nor on how many analyses the results are based; but I do not wish to question the increase of alumina in any of the altered rocks in the table on p. 260 as compared with the unaltered granite. The greatest increase is 2°09 per cent, which, added to the alumina of a pure orthoclase rock, gives a possible.36°3 per cent of topaz, which is still very far short of 90 per cent, and we are not dealing with pure orthoclase rocks. There can be no question that topaz does occur as an original rock constituent. The Meldon aplite, for instance, has been described anew recently,” in which topaz is associated with lepidolite, tourmaline, and fluorspar, among other minerals. There is no doubt in my mind that it occurs also as a pneumatolytic alteration product. Hach case must be decided on the local evidence. J. B. Scrivenor. YUNNAN CYSTIDEA. Str,—A few comments are necessary on Dr. Bather’s letter in the March number of this Magazine (p. 143) in reply to my remarks on his articles on Yunnan Cystidea. Especially is this the case with regard to the diplopores in Sznocystis. Firstly, it must be borne in mind that the figured specimens which were lent to him for a short time for the purpose of making casts for the British Museum constitute the only material on which he can base his conclusions, while I had three times the number of specimens for study for two years. Secondly, it has not been mentioned that these figured specimens before being drawn or sent to him had been cleaned under my eyes with a weak acid solution, which I then observed attacked and partially dissolved a few of the tubercles, so as to remove the thin covering layer of epistereom in some cases and thus expose the pores. Thirdly, the other specimens of Scnocystis, numbering over twenty, which Dr. Bather never saw, were examined by meas they came fresh from their limestone matrix, unaffected by weathering, untouched by any solvent, and often only partly exposed. These did not show any pores on the hundreds of tubercles which I scrutinized, except where the tubercles were obviously injured. Fourthly, his statement that on removing a piece of the matrix from one of my figured specimens there was disclosed a tubercle exhibiting the minute pores completely confirms my experience that there is extreme difficulty in getting rid of the closely adherent matrix without damaging the surface, and thus his discovery is of 1 Op. cit., pp. 259-60. * GEOL. MaG. 1919, pp. 41-2. 192 Obituary—Arthur Edward Victor Zealley. no value in support of his views. As I was ignorant that he was intending immediately to publish a detailed critical re-description of the species which I had established, and that all his evidence would be obtained from the few figured specimens which were lent for another purpose, the rest of the material was not put into his hands, and the unfortunate errors to which allusion has been made have thus appeared in his otherwise valuable articles on these interesting fossils. P.O enpe CAMBRIDGE. March 14, 1919. @XS IA eASE Nae ARTHUR EDWARD VICTOR ZEALLEY, A.R.C.S.; F.G.S. Born MarcH 1, 1886. DIED OCTOBER 28, 1918. A Most promising career has been cut short by the death of A. E. V. Zealley from pneumonia following influenza in the epidemic which visited Rhodesia in October, 1918. Zealley received his geological training at the Royal College of Science, London, and afterwards was appointed Demonstrator in Geology there. At this time he worked upon the metamorphosed limestones of Donegal, and published a short note in the Grotoeican Magazine for 1909, but the complete work is still in manuscript. In 1909 Zealley went out to Southern Rhodesia as Curator to the Rhodesia Museum. In that capacity he saw the collections housed in the first part of a building specially designed for a museum. He made important contributions to the Museum Reports on the minerals, on the mineral resources, and on the gold-bearing rocks of Rhodesia; and wrote articles and papers on the local minerals and rocks. Zealley joined the Geological Survey of Southern Rhodesia in 1911, shortly after it was started, and remained in that service until the time of his death. His work lay chiefly amongst the meta- morphic rocks, and he took part in the mapping of several of the goldfields. He was particularly interested in the ore-deposits, their genesis, and the association of minerals in them. He had gained a wide knowledge of the mineral deposits of the country, and his work was inspired by the belief that for their efficient development a thorough and exact study of them was necessary. When, after the War broke out, the systematic mapping of the Geological Survey was suspended, he threw himself whole- heartedly into the task of assisting prospectors with the determination of minerals and with advice as to the nature of the deposits they had found. He also took an active part in the work of the Rhodesia Munitions and Resources Committee, which has done much to spread a knowledge of the mineral wealth of the Territory. His ever-ready willingness freely to give his geological knowledge was much appre- ciated by prospectors and mining men, and will be greatly missed. H. B. M. “TABLE of BRITISH STRATA Henry Woopwarpb, LL.D., F.R.S., F.G.S. Horace B. Woopwarb, F.R.S., F.G.S. ANY years have elapsed since the publication of a Table of British Strata. The Table of British Sedimentary and Fossiliferous Strata by Messrs. H. W. Bristow and R. ETHERIDGE and that by Mr. Bristow, showing the Relative Thickness of the Strata, date back to 1873. Meanwhile many changes have been made in nomenclature, and many new local subdivisions have been marked out in the series of Strata. ‘T’o represent these in tabular form as an aid to the memory is one object of the present publication. The student should bear in mind that Nature does not draw the hard and fast lines which appear in the Table, and that the divisions, like those in human history, are epochs artificially limited for the convenience of grouping events. In many cases it is possible to indicate only the general position of the minor divisions in the great series of geological formations. Minute correlation of strata, dependent on organic remains, cannot here be attempted. The aim of the compilers has been to represent as fully and fairly as possible the views most widely accepted at the present time, and thus in grouping the Wealden in the Jurassic system and in retaining the Permian in the Paleozoic era they seek to assert general rather than individual opinion. Price 5s. net; Folded in bock form, 6s. net ; Mounted on linen, with rollers and varnished, 16s. net. ° LONDON: DULAU & CO,, LTD., 34-36 MARGARET STREET, CAVENDISH SQUARE, W. 1. GEOLOGISTS. SEVERAL Senior and Junior Geologists, preferably with Oil experience, required for Geological Surveys in various parts of the World by an important British Company. Liberal terms, according to qualifications. —Address, Le X22 eave Deacon's Advertising Offices, Leadenhall Street, London, E.C. 3. | SCIENTIFIC BOOKS and SERIALS. JOHN WHELDON & CO. have the largest stock in the country of Books in all departments of Science and Natural History, also Transactions and Journals of Learned Societies, etc., in sets, runs, and single volumes or numbers. Libraries or Small Parcels Purchased. SPECIAL CATALOGUES: Geological, Botanical, Zoological, Entomological, Ornithological, Chemical, Agricultural, Gardening, etc., 2d. each, post free. 38 GREAT QUEEN STREET, KINGSWAY, LONDON, W.C. 2. Telephone: GERRARD 1412. All communications for advertising space to be addressed to Mr. T. PRESTON, 41 Lullington Road, Anerley, S.E. 20. All Communications for this Magazine should be addressed to THE EDITOR, 13 Arundel Gardens, Notting Hill, W. 11. Books and Specimens to be addressed to the Editor as uswal, care of MESSRS. DULAU & CO.. LTD.. 34-836 MARGARET STREET, CAVENDISH SQUARE, W. 1G STEPHEN AUSTIN AND SONS, LTD., PRINTERS, HERTFORD. Pror. J. W. GREGORY, D.Sc., F.R.S. Sir JETHRO J. H. THALL, Sce.D., F.R.S. Sm 7T', H. HOLLAND, K.C.1I B., D.Sc., F.R.8. Pror. W. W. WATTS, Sc.D., F.R.S. Pro, J, E. MARR, Sc.D., F.R.S. Dr. A. SMITH WOODWARD, F.B.8. MAY, 1919. -CONTENTS :— Page REVIEWS (continued). Page EDITORIAL NOTES.......+..0sse00000.. 19351) Coal in Molland=«:-.:..cceke sickens 232 Aquamarine in Baltistan ............ 233 CECI NES MES Geology of Gomera (Canaries)...... 233 Foliation and Metamorphism. By Basalts of Antarctica..........+-.....- 234 Professor T. G. BONNEY ......... 196 | Seope of Paleo-ecology ..........2..+4 234 - On the Highest Coal-measures of Minerals from British Columbia... 234 Durham. By C. T. TRECHMANN Mimetite, Thaumasite, and Wavel- and D, WOOLACOTT .............-. 203 Life er een secon ne 935 The Minerals of the Lower Green- Augite from Stromboli ............... 235 sand. By R. H. RAsTatn ...... 211 | U.S. National Museum............+-- 235 Notes on Ammonites. V. By : eh CoO RATE Ss ce owneneeMcane 220 REPORTS AND PROCEEDINGS. Some Recent American Petrological Geological Society of London ...... 235 Ibn aHRURSS = Spbomnoorncdnnadenchonbdse 2267 Royal Society «acto ee 237 Kdinburgh Geological Society ...... 238 : REVIEWS, Mineralogical Society ............... 239 Hchinoids from the Bagh Beds ... 229 Gaabagt Bert ~ciecss. 5,5: eseeessounes 230 CORRESPONDENCE. Mineral Resources of Great Britain 231 | J. Reid Moir ...........ccsecceeeeeeeees 240 LONDON: DULAU & CO., Lrp., 34-36 Marcarer STREET, AND R: ft. BRASTALE, M.A; B.G.S. ASSISTED BY CAVENDISH SquarE, W.1. Cloth Cases for Binding may be had, price 2s. net. Nation al WuSf ia Pci ta MN SS a a AR RD Meh le ee 8 Pa tl ag AS © e- - Decade Vi-—Vok Vi--No. V. ~ “Pries Qs. Monthly Fournal of Geology. THe- GhOLOGIST, Asonian Insti un \ a EDITED BY os 4 40 Oo HENRY WOODWARD, LL.D., FR.SAS WAY 26 \4e : § \ JAMES SWIFT & SON, Manufacturers of Optical and Scientific Instruments, ees to all Scientific Departments of H.M. Home d Colonial and many Foreign Governments. Crands Prix, Diplomas of Honour, and Cold Medals at London, Paris, Brussels, ~ etc. MICROSCOPES AND OTHER INSTRUMENTS FOR ALL BRANCHES OF GEOLOGY, MINERALOGY, PETROLOGY. Sole Makers of the “ DICK > MINERALOGICAL MICROSCOPES. Dr. A. HUTCHINSON’S UNIVERSAL GONIOMETER. University Optical Works, 81 TOTTENHAM COURT ROAD, LONDON, W. 1 Watson’ Ss Microscopes for Geology. WATSON & SONS manufacture a special series of Microscopes for Geo- logical work. All have unique features, and every detail of construction has been carefully considered with a view to meeting every HeciLteanesh of the | geologist. All Apparatus for Ceology supplied. WATSON’S Microscopes are guaranteed for 5 years, but last a lifetime, and they are all BRITISH MADE at BARNET, HERTS. W. WATSON: & SONS, Ltd. (ESTABLISHED 1837) 313 HIGH HOLBORN, LONDON, W.C.1 Works:—HIGH BARNET, HERTS. ~ THE GEOLOGICAL MAGA Be NE WRSERIESH DECADE. VI: WOOL. AG Hson'2 No. V.—MAY, 1919. Fs VG Wanwe Vi AVY \ \ HEDITORTAT, 2 EE In: a] S will be seen from the official report reprinted plsewheren in “this issue, the Geological Society has decided at a Special General Meeting to admit women as Fellows. It was generally believed that the result was a foregone conclusion, and the figures of the ballot indicate that this belief was justified. As the President pointed out in his opening remarks, the Society has in the past pursued a rather hesitating policy with regard to this matter, and it is satisfactory to find that a clear and definite decision has at last been made on a motion initiated by the Council. ‘The work done in the past by a number of women geologists has been of a high order of merit, and the recognition of its worth will doubtless stimulate others to follow in similar paths and even to surpass the achieve- ments of the pioneers. Ere long we shall doubtless see ladies occupying seats on the Council and possibly even the presidential chair. . We have much pleasure in calling special attention to the paper appearing in this number of the Magazine under the title of ‘‘Foliation and Metamorphism in Rocks”. In this Professor Bonney gives a summary of the conclusions reached by him after an almost lifelong study of the subject both in the field and in the laboratory. It so happens that Professor Bonney’s active geological life nearly synchronizes with the existence of microscopic petrology ; he was one of the pioneers in this field and has had unrivalled opportunities of examining the gneissose and schistose rocks of many parts of the world, and especially those of the Alps. Again, he has devoted much attention to the origin of serpentine and cognate questions, both in Britain and abroad, with important results. Among other achievements Professor Bonney was one of the band of eeologists who set British stratigraphy free from the incubus of “altered Silurian”, and assisted to exorcise many other bogeys surviving from an earlier day. We feel sure that our readers will welcome this summary of the conclusions reached by one of the masters of petrology after nearly half a century of research, all the more because the observations on which the results are founded are entirely first-hand and independent of textbooks or preconceived ideas of any kind. * % * * * DECADE VI.—VOL. VI.—NO. V. 13 194 Editorial Notes. Fottowine a deputation to the Board of Trade from the Joint Industrial Council for the Tin-mining Industry of the United Kingdom, the Government delegated to the Imperial Mineral Resources Bureau the duty of making a preliminary inquiry into the position of the industry, which is, as is well known, in a parlous condition owing to the high cost of labour and material, without a corresponding increase in the price obtained for the main product of the mines, namely black tin or cassiterite. A committee was formed to undertake the work, Sir Lionel Phillips being appointed Chairman, and Dr. F. H. Hatch and Mr. W. Forster Brown, on behalf of this Committee, have recently visited the principal mines in the Camborne—Redruth area as well as those near St. Just and St. Agnes. At their request they were supplied with full data relating to the operation of the mines in the years 1912-18 inclusive. We understand that the report of the Committee, after approval by the Bureau, has been placed in the hands of the Government, and will be considered as soon as possible. % a % % % Tue lecture recently given by Professor Edgeworth David before the Geological Society gave food for a considerable amount of reflection on the importance of geology in warfare and the extraordinary inability of our military authorities to appreciate this importance. It was, however, fully realized by the Germans, who had a geologist for every 20 kilometres, as against one geologist for the whole of the British western front. This responsible post was held by Captain W. B. R. King, of the Geological Survey of Great Britain. On occasion Professor David also assisted with advice on geological matters, especially with regard to water supply, but as a rule no geologist was consulted until borings in unsuitable places had failed to find water, thus wasting time, labour, and money. Expert geologists were also urgently needed to advise with regard to tunnelling and mining operations; owing to ignorance of the position and depth of the water-table tunnels were frequently drowned out. A water-table map of most of the western front was eventually constructed, but it was impossible for the small staff to deal adequately with this and many other matters, such as prospecting for road-metal and other necessary supplies. Although many geologists were actually serving in the Army in various capacities on the western front, Headquarters did not seem to think that their services could be usefully employed; some of the Engineers high in authority did, however, realize the value of geology and would have liked more help, as is made manifest in a paper entitled ‘The Work of the Miner on the Western Front”, read by Major H. Standish Ball before the Institution of Mining and Metallurgy on April 10, and published in the Bulletin of the Institution for last month. This contains some brief but highly appreciative remarks on the geological work of Professor David and others. ‘The general con- clusion to be drawn is. that professional geologists ought to be permanently attached to all armies. % % * % * Editorial Notes. 195 Owine to the unprecedented demand for houses, a large amount of indiscriminate building will take place in the immediate future. A recent issue of the Observer contains a most timely article, signed “ Silex”, on the necessity for geological advice and control in these matters. There are few subjects on which more nonsense is talked and written than on the question of the suitabiiity or otherwise of various soils for residential districts. The general public has acquired some vague ideas as to the advantages of gravel soils and the supposed evil effects of clays, but the importance of taking into account other conditions as well is hardly ever realized. The man in the street is by no means aware that a gravel site in a hole, such as the Thames Valley, may be infinitely wetter and more unhealthy than a clay site on a hill, and similar instances might be multiplied indefinitely. It is highly desirable that local authorities before giving their consent to building schemes, at any rate on a large scale, should consult an expert as to the suitability of the area suggested for the special purpose in view, and that they should refuse their consent in the case of an unfavourable report. Neither municipalities nor the State can afford to allow the health of the people to be endangered or money tc be wasted in unprofitable and possibly injurious enterprises, when this can be prevented by sound scientific and technical advice. * * cs * * Mr. T. Saepparp has again earned a debt of gratitude for a remarkably interesting sketch of Martin Simpson and his career. He provides a pedigree, bibliography, and detailed description of his books and a variety of personalia now difficult to obtain, a facsimile of his writing and the well-known portrait. The paper appears in the Proceedings of the Yorkshire Geological Society, IK Ad) LOS. % * % % % Dr. H. 8S. Wasarneron contributes to Art and Archeology, vii (7), August, 1918, 256-63, a description and figures of a medal he acquired in Rome. Of Leonello Pio, Count of Carpi, it is cast in lead, and dates from about 1500. ‘The artist is unknown. The special interest of this medal lies in the fact that it represents a volcanic eruption, with ‘“lightning-charged” clouds, falling bombs, and lava-flow in realistic fashion, and Washington, from a most careful and elaborate investigation, thinks that it must represent the eruption of Vesuvius of 1500, described by Ambrosio Leone in Za Storia di Nola, 1514, which contains the oldest known figure of Vesuvius. If that is so, then the medal is probably a little earlier in date than the book. The legend on the reverse, surrounding the design of the mountain, reads MELIUS PUTATO, which Washington interprets as ‘‘more powerful (or active) than I have been thought to be”’, and he further points out that as the records of earlier eruptions are 1036, 1049, and 1139, the motto would be appropriate to the popular idea that the volcano was then extinct. ORIGINAL ARTICLES. 1.—Fotrrtion anp Mertamorpuism 1n Rocks. By Professor T. G. BONNEY, Se.D., LL.D-, F.R.S. InrRopucrorY. ae application of the microscope to petrology made it possible to investigate effectively the history of the foliated rocks and of metamorphism. This was done, as it happens, only a very few years before I began any special study of such rocks, so that the account of my own work almost corresponds with that of the general progress in a knowledge of them. I was led, after some preliminary efforts, into investigating two distinct problems, each of which, as I soon discovered, presented rather exceptional difficulties. These were the pre-Carboniferous rocks of Charnwood Forest and the serpentines of the Lizard. The problem involved in the one was how far some of them were or had been igneous in origin, lavas, tufts, and agglomerates, or were stratified rocks, which by pressure and mineral changes had been so altered as to be indistinguishable from some of the former. The other introduced the question of the origin of serpentine, about which in 1878 the utmost uncertainty existed.' This, from its associations, led on to investigating the nature and origin of gneisses and schists, so that the history of my own studies during the last forty-five years happens to illustrate some important aspects of the progress made during that period. So I have thought — that even now, notwithstanding the multiplication of textbooks and special memoirs (nay, perhaps because of it), some younger students may find it both interesting and useful to read the conclusions which I have been led to adopt, and to have their attention directed to investigations which were, to a large extent, independent and unbiassed. As my first paper depending on microscopic work was published _ early in 1877, anyone who consults those which have since appeared must not be surprised to find that my conclusions have been reached by degrees, and that some have had to be retracted. The former should be forgiven, because one frequently resembled a man feeling his way through a dense forest and the latter was often due to misleading information. More than once I have found that the old saying ‘“‘put not your trust in princes’ is true even in science. Of both these defects my work in Charnwood and at the Lizard affords instances. In the latter it was long before the real history, 1 The following remarks appeared in Rocks, Classified and Arranged (B. von Cotta; translated by P. H. Lawrence and published in 1866 with author’s preface of same date). After stating that serpentine is ‘* probably the product of the metamorphosis of some other rock’’, he continues (p. 317) : ““Tn some places . . . its transmutation from other rocks is very evident, as, for instance, from gabbro at Siebenlehn, near Freiberg; from dykes of granite traversing serpentine rocks near Béhrigen and Waldheim in Saxony, where the main serpentine itself is not improbably a transmuted granulite ; from chlorite- schist at Zell in the Fichtelgebirge, where the change does not appear to be yet complete; and from gneiss (probably) or an eclogite rock in the gneiss at Zdblitz in the Hrzgebirge.”’ Prof. T. G. Bonney—Foliation and Metamorphism. 197 as I believe it to be, of its gneisses and hornblende schists came home to me. The same holds good of the Alps, but in one paper relating to them, that on Zhe Carboniferous Gneiss at Guttannen,’ 1 doubt if I have not failen into one error while trying to correct another. Besides studying the slab supposed to contain two small tree stems in the Berne Museum, I visited Guttannen in 1891, 1895, and 1897, and in the last year saw an outcrop of the ‘‘ Carboniferous gneiss ”’ in the Urbach-thal. But it has since been proved that these objects are not fossils of any kind.’ How tHE PROBLEMS AROSE. On beginning to give lectures in Geology just half a century ago, I soon discovered how little I knew about that part of it which is now called petrology, and that the authors of the textbooks then in use were in much the same position. In England De la Beche, in Scotland Macculloch® had done most valuable work, but with their deaths not only had progress been arrested but also a movement had begun in a reverse direction. The application of the microscope to the study of thin slices of rocks, for which we are indebted to the inventive genius of H. C. Sorby,‘ arrested this movement and gave the student a surer footing. I began to work with this instrument about 1870 (tentatively at first, because at that time my eyes were far from strong), and for a while restricted myself to the igneous rocks, but I was soon drawn into those of the metamorphic group and was speedily confronted by statements which, as I was not long in finding, rested on very uncertain evidence. This forced me to enlarge my field of examination. Charnwood, as I have said, soon presented one set of problems, the Lizard another. The difficulties of the Llanberis district resembled the former, those of Anglesey to some extent approximated to the latter. Specimens sent to me by friends directed my attention to the alleged metamorphism in South-Western Ayrshire and in the North-Western Highlands, and I sought light on the difficulties of the latter by studying the eneisses and schists of the Alps, among which I often spent a summer holiday. Thus having done what I could, for nearly forty years, by work in the field and with the microscope, to solve some of the problems presented by the metamorphic rocks, I have thought that perhaps a short record of the results might be useful. It cortains, I fear, nothing new; probably everything in the following pages ‘‘has been said by somebody somewhere”’, but I may at any rate plead that my conclusions have not been taken ‘‘second-hand”. Asarule, 1 Q.J.G.S. xlviii, p. 390. 2 The story of this ‘‘ Comedy of Hrrors’’ is told in ‘‘ Plant Stems in the Guttannen Gneiss’’, GEoL. MAG. 1900, p. 215. 3 J. Macculloch died in 1835, H. T. De la Beche in 1855, but the ciouds were gathering again before the latter date. An excellent account of the difficulties which had to be encountered by those who were living and working in the earlier half of the nineteenth century is given by Sir A. Geikie in The Founders of Geology, ch. viii. 4 He began this work, for some years little appreciated, about 1850. 198 Prof. T. G. Bonney—Foliation and Metamorphism. I have consulted memoirs and textbooks only so far as to obtain a statement of the problems and to ascertain what places were likely to throw light upon them, and on this account ask my readers, if they think my conclusions wrong, before rejecting them contemptuously because they are unorthodox, to ‘‘go and see”—to examine nature for themselves, to collect their own specimens, and to study them with the microscope. FortateD Rocks. Foliation denotes a structure due to a more or less parallel ordering of certain of the mineral constituents in a rock which is not a direct consequence of its stratification. Such rocks are commonly called metamorphic, but that structure, as we shall see, is more often an original one than was once supposed. In a certain sense all rocks, except recent volcanic ejections and such sedimentaries as wind-blown sands and dusts, or diatomaceous earths, coral-reef limestone and even pure chalk, are metamorphic, because they have undergone some amount of mineral change since the time when they were first deposited. In a sandstone, forinstance, the fragments are cemented by a little secondary quartz or iron-oxide; in a limestone those of calcareous organisms are united by calcite; in an igneous rock the less stable minerals have undergone some change, but we do not consider this as amounting to metamorphism. To justify the use of that term, the bulk of the constituents, all in fact which are small in size, should have lost the aspect which was once characteristic; for instance, in a limestone the calcareous organisms should be no longer recognizable as such, and any constituent mud should have been converted into a mica or some other authigenous mineral. his may, however, happen, as we shall presently see, without resulting in a definite foliation. But in certain igneous rocks such a structure may be, not a superinduced, but an original one. Foliation, then, is produced by a parallel ordering of the authigenous platy or acicular constituents in a rock, and may or may not be associated with mineral banding.’ In the simpler case, when the constituents are not thus grouped, we find that the foliation is the result of movements in the mass, before it has become completely solid, though after most of its component minerals had segregated. Banded foliation, however, proves to be due, at any rate in many cases, to the movement of two associated magmas, different in chemical composition, both of which are in a somewhat plastic condition, though one may be more nearly liquid than the other. The two are forced along, sometimes without mixing, as two differently coloured glasses may be in the hands of a glassblower. Many varieties of rock, from acid to basic, from vitreous to holocrystalline, afford examples of this structure. I have studied its various stages in several places, of which the following may serve as examples. (a) On the southern half of Kennack Cove (Lizard) we can see veins of a grey granite breaking up a dark slightly foliated biotite-diorite, which it partly melts 1 See Manual of Geology, J. B. Jukes, 1872 (ed. A. Geikie), p. 142. . Prof. T. G. Bonney—Foliation and Metamorphism. 199 down, till a well-banded gneiss results from the movement of the imperfect mixture (1).! (4) A similar gneiss occurs in Kynance Cove and the cliffs to the south, though here the first stage is not so well illustrated (2). (¢) In Sark, on both the east and west coasts, we find a similar banded gneiss, produced by the intrusion of an aplitic granite into a basic diorite or hornblendite (3). The hornblende schists of the Lizard and of Sark also suggest a similar origin, viz., that after a moderately basic magma has been separated by differentiation into a more acid and a more basic part, the two, while still in a pasty state, have been forced to flow together (4). The different stages (d) of this process are very well displayed on the ice-worn rocks at the foot of the Allalin Glacier in the upper part of the Saasthal (5). Here a rather fine-grained aplite breaks into a mass of griiner Schiefer (probably a pressure-modified diabase). Sometimes the one rock simply forms veins in the other; sometimes the former breaks off fragments from the latter; sometimes it melts part of these, producing locally a fine-grained green-streaked gneiss. A process generally similar may be studied (¢) in the rocks under Castle Cornet, Guernsey (6). ‘Thus, as gneisses and hornblende- schists, exactly resembling those of which the genesis can be observed in the field and under the microscope, are by no means rare, we seem to be justified in concluding that this production of banded gneisses by partial mixture of more or less plastic magmas is one of frequent occurrence. 6. Foliation also may be produced in an ordinary holocrystalline rock by the action of pressure, more or less definite in direction, and sufficiently great to cause a partial crushing of the mass, which is succeeded by the formation of new minerals. Sharply folded rocks, such as often abound in mountain ranges, afford many examples of this kind of foliation. Here the quartz is more or less crushed; so also is the felspar, but this mineral, by the subsequent action of water (doubtless when the pressure was diminishing), is replaced by a mixture of granules of quartz and small scales of a white mica, the latter generally lying at right angles to the direction of pressure. - Thus a granite may exhibit all stages from an ordinary gneiss to a mica-schist (7), and a porphyritic granite those from an augen- gneiss to one characterized by thin and rather minutely crystalline bands (8). The so-called protogine of the Alps, which, instead of being the ‘‘first-born’”’ of their crystalline rocks, is intrusive into great masses of a more or less banded gneiss (sometimes rather rich in biotite), affords excellent examples of this, as in the Mont Blane range (9), on the upper part of the St. Gotthard Pass (10), and in more than one district of the Engadine (11). One form of “ pressure-gneiss’’ deserves special notice, because, till about thirty-five years ago, its origin was a geological puzzle. Of this the so-called Newer Gueisses of the North-West Highlands are an historicexample. These appear to overlie the basal Cambrian quartzite and some other sedimentary rocks belonging to the rest of that period and perhaps a little of the Ordovician. They form an 1 Figures in heayy type refer to the bibliography at the end of the paper. 200 Prof. T. G. Bonney—Foliation and Metamorphism. escarpment, often very conspicuous, which runs from the southern end of Loch Maree to the north of Loch Eriboll, the members of which are generally ‘‘slabby’’ in structure, composed mainly of quartz, felspar, and mica, though the minute scales of the last appear to have been formed in situ.!. This group of gneisses was asserted to represent a set of metamorphosed stratified rocks, approximately of Silurian age. Difficulties in this interpretation became graver as the knowledge of petrology increased, till, in the summer of 1882, the problem was finally solved by Professor Lapworth (12), who demonstrated that some of the pre-Torridonian crystalline rocks had been carried by .overfolding and overthrusting above sedimentaries of later date, and had been greatly crushed in the process. So these ‘‘ Newer Gneisses” are really Archean Gneisses, which have under- gone pressure-modification, a clastic structure (followed by a certain amount of mineral development, as described above) having been imposed on them at some epoch subsequent to the latest Cambrian and distinctly before the Devonian periods (18). A similar origin was claimed by Professor Lehmann in 1884 (14) for certain slabby gneisses in Saxony, but in this region the gneiss appears to have been more completely reconstituted, so perhaps the crushing may have occurred at an earlier date, or some local cause have favoured the repairing process. Rocks of a dioritic or doleritic nature also exhibit a pressure- foliation. The felspathic and ferro-magnesian constituents are crushed, and to a certain extent ‘‘rolled out”, after which they undergo a process of reconstitution, analogous with that which has been described in the case of granite rocks, but the original augite or hornblende is replaced by an acicular and generally rather smaller form ofthe latter mineral. ‘lhe rock becomes, in fact, an actinolitic schist, examples of which are common in the Alps (15). The more coarsely crystalline hornblendic gneisses, such as occur in the Lepontine Alps for some distance eastward from the south side of the St. Gotthard Pass (16) and in one or two parts of the Tyrol, also afford examples of a coarser form of pressure-foliation.’ The bulk of gneisses, especially the banded kinds, were formerly supposed to be metamorphosed sedimentary rocks. That was con- fidently stated less than half a century ago in textbooks of authority (17), and I well remember how often sedimentary rocks were said to pass (i.e. be melted down in situ) into igneous rock (18); nay, a metamorphic origin was sometimes attributed even to granite, because, as the specific gravity of its quartz was 2°65, and that of quartz which had been melted was only 2°25, the rock could not have been truly fused.* It is now not too much to say that the onus 1 Similar gneissoid rocks occur on the southern border of the Highland complex from near Stonehaven northward for some miles. ? Certain minerals, such as hornblende, biotite, chloritoid, ottrelite, dipyr, couseranite, and a plagioclase felspar, seem to form with comparative ease, as. will presently be described, in some crushed gneisses and hornblendic rocks. 3 The advocates of this notion appear to have forgotten that normal crystalline quartz is a frequent constituent of felsites, rhyolites, etc. Prof. T. G. Bonney—Foliation and Metamorphism. 201 pr obandi lies on anyone who claims a sedimentary origin for a gneiss, whether banded or not, and in the few cases where this can be proved the gneiss is usually limited in thickness and not quite normal in character ; ; sometimes, indeed, the supposed gneiss is found on closer study to be merely a rolled out sill or vein of intrusive granite (19). Thus it is prudent, in dealing with gneisses which show no signs of passing, on the one hand, into schists by a gradual transition, on the other into indubitable granites, to carry them for the present to a ‘‘ suspense account’’. I pass on now to those crystalline schists which can be proved to be metamorphosed sedimentary rocks, viz. the group of the quartz- schists, quartz-mica-schists, cale-mica-schists, and crystalline marbles (or dolomites). These sometimes overlie, with marked unconformity, the above-named gneisses, though occasionally it is difficult to divide them. The same may be said of their relation to the overlying hypometamorphic or unmetamorphie strata, but in many cases their division from the one or other is not quite so clear. The sedimentary origin of these crystalline schists, if we except the griiner Schiefer (and we must not exclude the possibility of some of these being metamorphosed tuffs), is unquestionable. In chemical composition they agree with corresponding members of the stratified rocks, and are associated in exactly the same way. Of these associa- tions striking instances may be found in the Val Canaria, Val Piora, on the Nufenen and the Gries Passes, in the neighbourhoods of Binn, Saas, Zermatt, and at sundry localities in the French, Italian, and Austrian Alps (20). Here we can find dark or lead-coloured mica- schists, sometimes containing garnets (which may be as large as peas) interbanded with quartz-schists or passing rapidly into cale-mica- schists and marbles. They show the effects, often conspicuously, of subsequent pressure (21), but careful study makes it obvious that before this acted they had been well metamorphosed, that change having been due to the joint action of pressure, water, and heat, of which probably the last agent was niost above the normal. We infer this from the fact that stratified rocks, which must have been depressed to very considerable depths from the earth’s surface, and have been kept for a long time sodden with water, do not exhibit this kind of metamorphism. Its occurrence has often been con- fidently asserted, but every instance, such as the ‘‘fossiliferous schists’? of more than one part of the Alps and the ‘‘ Devonian schists’’ of the Start district, has broken down, on careful study in the field and with the microscope, like the ‘‘ Newer Gneisses’’ of the Highlands. A quartz-schist consists mainly of grains of quartz, but usually contains small flakes of white or lead-coloured mica, which occasionally form distinct and rather conspicuous bands (22). The purer varieties are almost white and slightly slabby (perhaps a superimposed structure. When this schist rests on gneiss its lower part occasionally contains some fragments of felspar and (in a few eases) pebbles of vein quartz or some compact rock resembling a halleflinta (23). Evidently the purer varieties much resemble quartzites, but they present under the microscope a different 202 Prof. T. G. Bonney—Foliation and Metamorphism. structure. The quartzites consist of distinct grains, angular or rounded, cemented together by a secondary deposit of quartz, often in crystalline continuity with the original grain, but those in a quartz- schist are rather more irregular and indefinite in outline, so as to give . the matrix a slightly streaky structure and even to suggest the possibility that, like the mica,they are authigenous. The quartz-schists frequently pass up into mica-schists, and in one part of the Val Piora a fairly normal example is associated with a mica-schist containing many rather large staurolites (24). In this district masses of very dark mica-schist are abundant, and their lower part is sometimes repeatedly interbanded with a not very pure quartz- schist. Garnets occur in both these rocks, but are more abundant and rather larger in the mica-schist. The same garnet-bearing dark mica-schist occurs at the Alp Vitgira on the Lukmanier Pass (25) as well as on the Nufenen Pass (26) and in the Binnenthal (27). The dark miga-schist in the Val Piora apparently passes locally into cale- mica-schist, and itisfound in aravine on the western side of the Val Canaria, associated with a pale-coloured schist, largely composed of two species of mica, and with a cale-mica-schist, locally passing into a white marble.” In fact, these different kinds of schists may be seen to pass one into another, just as sandstones, clays, and lime- stones do among the ordinary sediments, so there cannot be any doubt that they are the metamorphic representatives of such rocks. In the Alps the overlying slates and other sedimentary rocks, as a rule, are readily distinguishable from the above described schists, but at one or two localities, authigenous garnets and staurolites have been asserted to occur with belemnites, joints of crinoids, and other fossils, which prove the supposed schists to belong to the Lias (28). This assertion finds a merely superficial support from field evidence and breaks down wholly when tested with the microscope. The minerals associated with those organisms and called garnets and staurolites are neither the one nor the other, but only some silicates too impure to be identified with certainty; but probably allied to dipyr and a colourless chloritoid, which, under certain circumstances, form with comparative ease® and do not indicate sufficient metamorphic action to obliterate any organism, though this is generally one of the first things to disappear before a marked rise of temperature. Nature has, in fact, been setting traps for the unwary petrologist. In some localities the apparent passage from a dark crystalline 1 The pressure-modified quartzites of the Scotch Highlands, such as those of Glendhu in Sutherland, present the nearest resemblance to a true quartz- schist. ? Descriptions of these schists, together with analyses quoted from an article by Dr. Grubenmann (Mitth. Thurg. naturf. Ges., Heft viii, 1888), are given in a paper on ‘Crystalline Schists and their Relation to Mesozoic Rocks in the Lepontine Alps’’ (Q.J. 1890, pp. 187-236). The garnets appear to be an impure representative of the alumina-lime variety. They are sometimes about one-third of an inch in diameter. 3 They had already been analysed (see Q.J.G.S. 1890, p. 233) by Fritsch (Beitrage zur Geol. Karte der Schweiz, Lief. xv, p. 127) and the impossibility of identifying his knoten and nrismen with garnet and staurolite implicitly demonstrated. Highest Coal-measwres of Durham. 208 schist to a slate is due to exceptionally severe pressure having locally converted the slate into a phyllite and so far crushed the schist that it is hardly distinguishable from the latter rock. ‘his may be seen, for instance, in the I'yrol on the ascent from Mittersill to Kitzbihel (29), and in the cliffs south of Torcross in Devon (30). (To be continued.) T1.—On true Hicuusr Coan-MEASURES on ‘“‘ ZoNE” oF ANTHRACOMYA PHILLIPsSt IN THE DurwAamM CoALFIELD. By C. T. TRECHMANN, D.Sc., F.G.S., and D. WooLAcoTT, D.Sc., F.G.S. (PLATE VY.) T has been known for some considerable time that the highest beds of the Northumberland and Durham Coalfield lie approximately beneath the town of Sunderland.! The great syncline of the Coal- measures of this area is distinctly accentuated in North-East Durham, so that a secondary basin-like depression is formed, in the centre of which these high beds occur.? Beneath Sunderland, where the top layers also exist, the Carboniferous rocks are concealed by the overlying Permian strata, but at a place called Claxheugh on the Wear, about two miles west of Sunderland, the Coal-measures are exposed for a short distance on both the north and south banks of the river. These beds represent the horizon known as the zone of Anthracomya Phillipst. It is not generally known among British geologists that these specially high beds occur in the northern coalfield, so that we consider it desirable to put this fact definitely on record, and to add some details on the stratigraphy and paleontology of the beds in question, the result of several visits to the locality. The section described is exposed on the north bank of the Wear, and is the one that is specially fossiliferous. The shale, with the bands of clay ironstone from which most of the fossils are obtained, does not occur in the section on the opposite side. The small section of Coal-measures, about 90 yards long and about 15 feet high, is cut off by a fault on the west which throws down the Permian Yellow Sands. This is the same displacement that brings down the Permian rocks, which are so well exposed in the Claxheugh escarpment.2 The Carboniferous rocks consist of argillaceous sandstones at the base, a layer of dark fissile shale, 3 feet thick, with two or three irregular nodular bands of clay ironstone, and beds of grey sandy micaceous shale. The sequence is shown in the section, Fig. 1. During one of our visits to the locality, Dr. Woolacott observed that the exposure, besides the four 1 J. W. Kirkby, ‘‘ On the Occurrence of Fossils in the Highest Beds of the Durham Coal-measures’’: Trans. Tyneside Nat. Field Club, vol. vi, pt. i, pp. 220-5, 1864. -2 1D. Woolacott, ‘‘ Stratigraphy and Tectonics of the Permian of Durham (Northern Area) ’’?: Proc. Univ. Durham Phil. Soc., vol. iv, pt. v, p. 246, 1911-12. 3 D. Woolacott, ‘‘On Sections in the Lower Permian Rocks at Claxheugh and Down Hill, Co. Durham’’: Trans. Nat. Hist. Soc. Northumberland, Durham, and Newcastle-upon-Tyne, N.S., vol. v, pt. i, p. 155. C. T. Trechmann and D. Woolacott 204 *sqney tours, *7, "SOINSVOUI-[BOH OY} JSUIBSB SPUBO MOT[9X OY} SUIMOIYY yINVA “7 “Avjo-repjnog °*G “poinjoviy TONUL ‘(UBIUIIEd) SpuUBy MOT[EX "PF ‘areys snosovorm Apuvs Aeir) °g “‘Suysniyqy jo ouvjd vw st4y *(g “SI 908) AY Aq poq[nvy Suteg you *D Spavmoy oyBys oy} UT [PAS] OUTLS OT} 4B UO FYSIVIYS ponUTyUOD ST 41 4ySvO Bq} OF 4nq ‘e[BYys ey Jo do} oy} UO ST 41 AY JUSWO[ASIp [[VUIS 9} JO SEM Ol] OT, “SS9UHOTYF UI ‘UIST eTBYs Uexo1q pus dn punois puv Avo popisuexor[s Jo yok B SI OIA oAOGB ‘spUeq MOYSUIOAT YIM (YOry} 9007 G) PTVUS ~% “goINOVIT Av[NSattt SUOTS UMOIG-YSTMOT[eL pourTeys ouOSpUBS SNOsdET[IIIE pemopoo-yqsry ‘T 4 (-yjoowjoo “gq Aq UMeIq) “HNVId-ISNUH], GNV SGNVG ANOISNOY] SAOUTAITISSOY 10 NOILISOG DNIMOHS NOILOaS—'T “DI ‘Seuokoz ‘Ol oO "HOsD}OOMA ‘Gg Highest Coal-measwres of Durham. 205 or five faults that occur in it, includes a peculiar layer, 14 inches thick, of slickensided, broken up, and powdered shale, which occasionally splits and does not maintain a constant horizon in the shale (see Fig, 2). This disturbed band marks a plane of thrusting, the beds above having moved on the upper layers of the shale, the powdered and broken | up material acting as a lubricant. It is impossible to say whether the displacement is of large or small magnitude owing to the faults which cut out the beds, but it seems probable that the movement to which this slickensided layer is due was produced by the same forces that caused the extensive series of horizontal movements, which have been proved to have occurred in both the Coal-measures and the Permian rocks of South-East Northumberland and North-East Durham,! the results of which are so well exposed in the Permian rocks of Claxheugh.? These fossiliferous Coal-measures are the highest visible in the northern coalfield. Those situated immediately under Sunderland are inaccessible to research, and any evidence available from borings or pit-sinkings can yield little paleontogical evidence of value, but it can be fairly safely asserted that those that occur in this section cannot be more than 50 or 60 feet below the top of the Coal-measure floor, as it existed just previously to the deposition of the overlying Permian. Also our knowledge of the lie of the coal-bearing rocks beneath the east of Durham enables us to assert that they are near the top of the highest Carboniferous strata, as these occur in Northumberland and Durham. This zone, therefore, is of importance, since it marks the upper limit of the Coal-measures of these two counties. Evidence bearing upon the height of these beds above the chief workable seams of the district has been obtained from details of the - sinkings at Hylton Colliery, which is situated about a quarter of a mile to the east and Monkwearmouth Colliery about 2 miles in the same direction. No intervening faults of any great magnitude occur. At the former colliery the thickness of the Coal-measures to the main coal of the Wear is about 1,300 feet, and to the Maudlin or Bensham seam about 1,375 feet, while at the latter the thickness to the main coal is about il 170 feet, and to the Maudlin 1,265. Near the top in the Hylton sinking some bands of clay ironstone are recorded, which may very well be the same as those at Claxheugh, as the beds dip gently in an easterly direction. PAaLHONTOLOGY oF THE CLraxHEvGcH Bens (C.T.T.). ** Aneylus” Vinti, Kirkby. (Pl. V, Figs. 1-4.) This problematical fossil occurs in great numbers in the layers of clay ironstone. Generally the specimens are more or less crowded together along certain bands in the rock to the exclusion of other fossils, but occasionally they occur scattered about on the surfaces that yield the bivalves of the group of Anthracomya Phillipsi. 1 The evidence is detailed in ‘‘ Stratigraphy and Tectonics of the Permian of Durkam ’’: op. jam cit., pp. 288-99. 2 Op. jam cit., p. 159. 206 C. T. Trechmann and D. Woolacott— One of my specimens measures 2mm. in length and slightly over 1-5 mm. in height; another is 3mm. long and 2 mm. high. Kirkby wisely declined to arrive at any definite decision as to the real nature of this organism and stated clearly his reasons both for and against regarding it as an Ancylus,a Discina, an Lstheria, or a bivalve mollusc. Some later geologists have, however, adopted a less cautious attitude, and Dr. Wheelton Hind has definitely described and figured specimens from Claxheugh as a lamellibranch, calling them Carbonicola Vinti.. Carbonicola is a genus which bears hinge-teeth. Xx D.W. Fic. 2.—SECTION AT XY IN Fie. 1. (Enlarged.) Sh. Shale with fossiliferous ironstone bands, slightly faulted along XY; the fault dies out in the upper beds. CO. A band of slickensided clay and broken shale (14 in. thick), which on the west of the section runs along the top of the ironstone band beneath the sandy shale, but is not faulted by XY, being continued straight on in the bed of shale. This layer lies along a thrust-plane. 1. Light-coloured argillaceous sandstone. 2. Thinly bedded sandy micaceous shale. He regards the Claxheugh specimens as ‘‘the closely compressed remains of the periostracum of a large number of shells”. My examination of a large series of specimens, however, reveals difficulties in accepting this view. They show no trace of calcareous matter and seem to have consisted entirely of chitinous material, but on the same slab one observes numerous valves of Anthracomya, and of small entomostraca still retaining their calcareous nature, so that it is not easy to believe that the valves of ‘‘ Carbonicola”” Vinti have become decalcified, while those of other equally delicate calcareous organisms have remained unaffected. The Claxheugh specimens are clearly not-shells which have been partly decomposed or decalcified. However, a speaker at the discussion on the above-mentioned paper assumed that the bivalve nature of the fossil was decided. It is clear to me from examination of my specimens that the organism 1 ““ On three New Species of Lamellibranchs from the Carboniferous Rocks of Great Britain ’’: Q.J.G.S., vol. lv, p. 365, 1899. Highest Coal-measures of Durham. 207 was bivalvular and cannot be either an Ancylus or a Discina. It seems unfortunate, however, that a shell from the Upper Coal- measures of the North Staffordshire Coalfield, which from the illustration and description seems beyond doubt to be a true and adult form of Carbonicola, should have had the specific name of ‘¢ Vintec”? attached to it on the assumption that it is identical with the chitinous organism from Claxheugh. The name has now found its way into Continental publications. E. Haug,’ speaking of the Coal-measures of Great Britain, says: “The Upper series is characterized by intercalations of beds of Anthracomya Phillipst and Carbonicola Vinti, lamellibranchs generally regarded as freshwater forms.” Kirkby, as his habit was, gave an accurate description of the organism, and one can add little to his diagnosis, which is as follows: ‘‘length one-twelfth to one- eighth of an inch, breadth one-fourteenth to one-tenth, sub-oval or nearly circular, with the posterior margin straight, flatly patelliform, with an eccentric reflexed apex posteriorly placed, shell delicate, surface ornamented with several rather coarse concentric plaits.”’ I am much indebted to Mr. H. Bolton, M.Sc., F.G.S., to whom I submitted some of the specimens for the suggestion that these organisms are the ‘‘spat”’ of Anthracomya Phillipsi. He writes: “‘T have examined the fossils you sent me, especially the example of ‘Ancylus ( Carbonicola)’ Vinti, and have found them of more than usual interest. In the first case I fail to see any Carbonicola character at all in any of them: what I do see, is that so far as my experience goes, you are dealing with ‘spat’ and not with adult forms of mollusca. I gave a long time to the study of the life- history of Anthracomya Phillipsi, and had the advantage of a great series of specimens from several coalfields, whilst I had the experience of thirty years to aid me. I feel convinced that your specimens and the Ancylus (‘ Carbonicola’) Vinti are nothing but the spat of Anthracomya Phillipsi. As you will see by my paper,’ I have linked three former species, viz. Anthracomya levis var. Scotica; A. minima; and A. Phillipsi. The first is the ‘spat’ stage, the second the adult stage, and the third the senile stage of the one species. I shall be interested to learn whether your Ancylus Vinti ever occurs away from the Anthracomya Phallipst. Of course it may, but I think you will find the other two species not far off. The ‘spat’ stage has usually a short straight hinge-line, and the valve is perfectly symmetrical to it and not oblique at all; the obliquity comes in with the ‘minima’ stage. Until the latter is reached the central and youngest part of the umbones remains fairly elevated and convex. As the‘ minima’ stage increases the new shell matter is added to the ventral-posterior border at a much greater rate than elsewhere, and asa result there is an increasing obliquity, which reaches its maximum in the ‘ Phillipsi’ stage. I have seen shells so well preserved that you can mark off the three stages on the surface on the one shell.” 1 Les Périodes Géologiques, vol. ii, p. 764. 2 “Fauna and Stratigraphy of the Kent Coalfield’’: Trans. Inst. Mining Engineers, vol. xlix, pt. iv, p. 33, 1915. 208 0. T. Trechmann and D. Woolacott— On my inquiring further in this matter Mr. Bolton writes: “With respect to the shell of 4. Vint’, I think that in the ‘spat’ stage there was little or no calcification. I would not be sure, but I rather fancy that the shell is little more than a top integument, and may possibly be represented by the periostracum at a later stage. I am assuming this from the Glochidia larva of the common Swan Mussel. I have not seen the latter for some years, but I think the valves are well domed and hooked at one end, so that the larve can hang on to the gills of the parent; afterwards calcification takes place in regular concentric layers around the umbonal point, and the hooked condition is left together with the tegumentary-like appearance; and the shell assumes more or less the appearance of the adult stage.” It was, therefore, a matter of interest to me to try and observe whether on any of the Claxheugh specimens one could see the ‘‘spat’’? form in the act of growing into the A. devs form or whether the umbones of the larger shells showed any trace of the wrinkled stage of the spat. J examined all the available specimens with this point in view. Certainly there are no specimens of Anthracomya on the slabs of smaller size than ‘‘ Ancylus’’ Vintz, which is a fact in favour of the latter being actually the young stage of the Anthracomyas associated with them. In one or two instances there seemed to be evidence of the wrinkled periostracum of the ‘‘spat”’ stage remaining on the umbo, though in nearly all the specimens after the calcification of the interior of the valves of the spat, the character of the shell seems to change rapidly and the periostracum to disappear. (See Pl. V, Figs. 6 and 7.) Notwithstanding these difficulties I am quite inclined to agree with Mr. Bolton’s interesting suggestion that all the bivalvular organisms in this bed belong to different stages of growth of one and the same shell, commencing with ‘‘ Ancylus”’ Vinty and ending with Anthracomya Phillipst. One slab shows clear evidence of an ‘‘ Ancylus’’ Vintv with incipient calcified growth-lines developing round the anterior, posterior, and lower margins. I may here remark that the apex of ‘‘ Ancylus”’ Vinti does not correspond with the beak of the more adult form Anthracomya minima. In the former, in well-preserved examples, the rounded and rather indefinite apex never occupies the hinge-line but is situated well below it, and anterior to the middle of the shell, or eccentric, as Kirkby described it. Anthracomya Phillipst (Williamson). (Pl. V, Figs. 5-7.) Bivalves having the appearance of this form occur in great numbers more or less crushed in the two bands of clay-ironstone in the Claxheugh section. My specimens vary in size from 6 mm. long and 3 mm. high to 32 mm. long and 14mm. high, and certainly appear to me to represent various stages of growth of one and the same species. No other bivalves have been found in these beds, consequently the Highest Coal-measwres of Durham. 209 group of shells appears to mark a definite horizon in the Durham Coalfield. Not much zonal collecting of the fossils has been done in the Coal- measures of this district, but I have a fair number of bivalves, mostly collected at different times from pitheaps, and the Newcastle Museum also has a number of specimens. From these it is possible to ascertain roughly the sequence of the ‘‘ mussels”’ in the main Coal- measures of Durham and Northumberland. Kirkby, in 1864, mentions the shell that occurs at Claxheugh as Anthracomya acuta, a species which is now placed in the genus Carbonicola, but he gives no description of it. I submitted some of the smaller Claxheugh shells to Mr. Bolton who returned them to me labelled ‘‘ Anthracomya minima stage of A. Phillipsi””, and he remarks in a letter, ‘‘I have been breaking up the ironstone nodules you sent and am extremely interested to note that they contain beautiful examples of 4. minima, the intermediate stage between A. levis var. scotica or ‘spat’ and the adult A. Phillips«.” : I am not sufficiently well acquainted with the mollusca of the Coal-measures to be able to discuss whether Mr. Bolton’s views on the various growth stages of this shell are in every instance correct or not. It is also very difficult on reading the various publications on the question to determine whether or not A. Phillipst represents a distinct zone in the English Coal-measures, and its recorded distribution offers some points that require further elucidation. In the North of England its horizon seems to be a well defined and restricted one. In Yorkshire it is reported, so far as I can ascertain from one locality only,! namely, from a cutting near Conisborough, in © a band of soft ironstone about two inches thick among clays and sandstones underlying the Permian. In the Nottingham area Messrs. Lamplugh and Gibson? say that ‘‘ the range of the distinctive species of the genus Anthracomya has not been definitely fixed but A. Phillipsi occurs in the top beds of the middle Coal-measures at Gedling”’, and Mr. R. D. Vernon informs us that A. Williamsonz (Brown) invariably accompanies the roof shales of the ‘‘Top Hard Coal”’. In the concealed coalfield of Yorkshire and Nottinghamshire its horizon seems also to be a definite one where it has not occurred below the Top Hard or Barnsley Coal, and is regarded as characteristic of the Middle Coal-measures above that seam.° Matters, however, in the South of England, are much Jess clear and Mr. H. Bolton‘ states that ‘‘ Anthracomya Phillipst is equally abundant in the lower Coal-measures of the Bristol district and in the upper series of Radstock’”’. In the Kent Coalfield a similar uncertainty seems to prevail. Mr. Bolton, referring to Anthracomya levis, A. levis, var. Scotica, 1H. Culpin & G. Grace, Naturalist, No. 577, February, 1905, p. 40. 2 Geology of Nottingham (Geol. Surv. Mem.), 1910, p. 17. 3 Walcot Gibson, Geol. Surv. Mem., 1913, p. 25. 4 Q.J.G.S., vol. lxvii, No. 267, p. 329, 1913. DECADE VI.—VOL. VI.—NO. V. 14 210 Highest Coal-measwres of Durham. A. minima, and A. Phillipst, says they are the dominant fossils of the Kent Coalfield and occur in countless numbers and at many horizons. The remaining animal fossils at Claxheugh require little notice. On a recent visit I was fortunate to collect in the sandy shales above the clay-ironstone bands a small limuloid crustacean, which Dr. H. Woodward has described as a new species of Bellinurus under the name of B. Zrechmanni.1 The specimen is now in the British Museum (Natural History). Insect remains were found here many years ago, “ne no one has. since succeeded in finding any more of them. Kirkby records them as Etoblattina Mantidioides,Goldenb. ; Lithomylacris Kirkbyi, H. Woodw.? Fic. 3.—Bellinurus Trechmanni, H. Woodw., sp. nov. X 4. Upper Coal- measures: Claxheugh on the Wear, Sunderland. ‘Fish-seales are fairly plentiful. Dr. A. Smith Woodward was kind enough to examine those I collected and reports that they are ‘‘ Well-preserved specimens of the scales of Lhizodopsis sauroides ( Williamson) ”’. Ostracoda are common but have not been examined in recent times. Kirkby recorded the occurrence here of Beyrichia arcuata, Bean, and another small entomostracan related to Cythere or Cypris. : ; Prant Remarns. Plant remains are rather scarce at Claxheugh, but occur in the ironstone bands. Hoping to obtain some results I kept all the specimens I collected from time to time and have recently sent them to Dr. Kidston, F.R.S., who has very kindly identified them, and has given me the following list of species and the results of his examination of them. ‘Those that are sufficiently good for determination are Neuropteris gigantea, Sternb. Calamites suckowt, Brongt. Lepidodendron simile, Kidston. Lepidophyllum triangulare, Zeiller. Sigillaria discophora, Konig sp. 1 GEOL. MAG., Dec. VI, Vol. V, p. 470, 1918. 2 GEOL. MAG., Dec. I, Vol. IV, p. 390, Pl. XVII, 1867. Grou. Mac., 1919. Prati V. C.T.T. photo. Bale & Sons, imp. SLABS OF CLAY-IRONSTONE FROM THE HIGHEST COAL-MEASURES, CLAXHEUGH, CO. DURHAM. R. H. Rastall—Minerals of Lower Greensand. 211 ‘Tt is difficult, owing to the small number of species collected, to give a definite horizon. There are no specially characteristic species contained, but it is either Westphalian or possibly the Black Band group of the Staffordian series which immediately overlies the Westphalian. There is nothing in the collection to enable one to decide this.” EXPLANATION OF PLATE V. Slabs of clay-ironstone from the highest Coal-measures at Claxheugh, co. Durham. Fic. 1.—Surface with a number of individuals of *‘ Ancylus’’ Vinti, Kirkby. eae to be the ‘‘ spat’’ of Anthracomya Phillips: (fide Herbert Bolton ,, 2.—Ditto, the individuals more crowded together. ,, 8.—A specimen of ‘‘ Ancylus’?’ Vinti, Kirkby, from slab (Fig. i), x 5. ,, 4.—Another specimen of same, from same slab. x 5. »» 9.—Slab covered with lamellibranchs. The largest specimens are Anthracomya Phillipst (Fig. 6); the smaller ones are A. minima, Ludwig, the younger stage of A. Phillipst. Some of these have the umbones wrinkled and incompletely calcified, recalling *“Ancylus’’ Vintv. Specimens of A. vinti occur also on this slab. », 6.—Anthracomya Phillipsi, from slab 5. x 4. », «.—Another younger specimen of same, ditto. x 4. Il].—Tuer Minerat Composrrion of THE LowER GREENSAND Srrara oF Kastern ENnGLanD. By R. H. RASTALL, M.A., F.G.S. ie the year 1913 the author formed the intention of carrying out a comprehensive investigation of the mineral composition of the Lower Greensand strata of England,in order to ascertain whether any definite conclusions could be drawn as to the sources of the material and the geographical conditions that existed while the deposits were beingformed. A large number of specimens were collected along the outcropfromthe Wash to the borders of Buckinghamshire and examined by the usual laboratory methods. This work was interrupted by the outbreak of war, and on returning to Cambridge after an absence of nearly four years on Government service circumstances proved to be unfavourable to a continuance of the work on the scale originally contemplated. The district already dealt with forms in _ itself a fairly well-defined unit, and it was decided to publish an account of the results already attained, in the hope that they may be of service to future workers in this interesting field of petrological and stratigraphical research. : INTRODUCTION. The formation generally known as the Lower Greensand attains a considerable development in the eastern midland counties of England. It has an almost continuous outcrop from the shores of the Wash to the western borders of Bedfordshire, but further to the west it is discontinuous and does not appear at the surface over long stretches of country, being overlapped by the Gault. It is a question still undecided whether it was ever deposited continuously in this region and afterwards removed by inter-Cretaceous denudation, or 212 Rk. H. Rastall—Minerals of Lower Greensand. whether, on the other hand, there were from the beginning gaps in the succession owing to intervening land-areas. At all events, it is certain that the Lower Greensand thinned out towards the south against the high ground of the London Paleozoic plateau, which was first completely submerged in Gault times, as shown by the records of numerous deep borings. The thickness of the Lower Greensand within the district as above defined undergoes certain remarkable and more or less regular variations, and the present author has already put forward reasons for believing that this variation is due to the existence in Lower Cretaceous times of a ridge of land running in a general north-west to south-east direction, parallel to the known strike of the Charnian rocks, and probably due to posthumous movements of an ancient fold-line.1 Repeated movements of this axis have been clearly demonstrated in other instances by Professor Kendall,” although he expressly disclaims any belief in its. influence on the Lower Greensand. On that point the present author ventures to maintain his own opinion. It is at any rate a striking fact that the strongly marked diminution in thickness of the Lower Greensand takes place just over the district where it might be expected on this - supposition. In the west of Bedfordshire it is 250 feet thick, in Norfolk about 150 feet, whereas at Upware and Ely there are only a very few feet, and it is possible that in places it is absent altogether. These facts can only be accounted for by overlap against a land-surface, apparently an isthmus dividing two seas, which was gradually being submerged and was finally overflowed at the beginning of Upper Cretaceous times, since there is no doubt that the outcrop of the Gault is continuous, although the thickness of this formation diminishes greatly towards the north-east. The stratigraphy and paleontology of the Lower Greensand present many problems of great interest and difficulty; some of them are still matters of discussion, as, for example, the true age and origin of the so-called ‘‘derived”’ fossils, which are so common in the pebble-beds of some districts. The present author is not competent to deal with this and other cognate matters, nor with the question of the exact correlation of the strata of the midland and eastern counties with those seen elsewhere. The object of the present paper is merely to set forth the results of a mineralogical examination of the sands of certain areas in the hope that the facts ascertained may assist in throwing light on some factors of a larger problem, which must eventually be dealt with by others. 1. Carstonz, Hunsranton. The general character of the rock forming the lower part of the cliff section at Hunstanton is so well known as scarcely to require detailed description. It must suffice here to say that the finer beds consist of a highly ferruginous sand, each grain being coated by a pellicle of iron oxide, and the whole more or less cemented by the same substance. Owing to this circumstance the preparation of the material for minute investigation presents considerable difficulties. Rastall, Geology in the Field, 1909, pp. 140-4. 2 Kendall, Report Coal Commission, 1905, pt. ix, p. 30. R. H. Rastall—Minerals of Lower Greensand. 218 Even after very prolonged digestion with strong hydrochloric acid it is difficult to get rid of all the brown iron oxide, which clings very closely to the grains, and often forms oolitic structures apparently possessing a skeleton of silica.'| This sand also contains a good deal more carbonate than those from most other localities, though in this respect it does not approach the calcareous sandstone of the Ely outlier. ~ When the residue from the preliminary panning, 80 very necessary in this instance, is digested for a long time with acid, it is found that a large proportion of the separated material consists of brown grains of oxidized glauconite; owing to their low density most of these can be got rid of by shaking and washing in a watch-glass or shallow dish before the bromoform separation. This is an advantage from the point of view of economy of bromoform. Even while the separation in the heavy liquid is in progress it is evident that the average size of the grains that sink is greater than usual, and especially greater than in those specimens from the western and southern areas. This is abundantly confirmed in the microscopic examination of the material, when the difference is very noticeable at the first glance. Several distinct samples from different horizons in the cliff were separated with the most careful treatment adapted to the special circumstances; all were, however, so closely similar that one general description will suffice. The characteristic minerals are kyanite, staurolite, rutile, zircon, tourmaline, and garnet. The inevitable ilmenite was abundant, and both hornblende and diopside were present in small quantities, as well as an immense number of minute flakes of muscovite. The crystals of kyanite are abundant and large and as a rule not much rounded, some being quite angular and blade-like; they show clearly the normal extinction angle of 30° and the emergence of a negative bisectrix normal to the principal cleavage, on which the erystals always lie. Staurolite is common in angular chips, much larger than usual, and also in grains of smaller size and more rounded form; it is of the ordinary bright orange colour, with distinct pleochroism. Rutile is abundant in large grains, generally much rounded, varying in colour from a bright orange to a deep blood-red ; some show good twin-lamelle on the common law. Tourmaline is moderately abundant; it is usually in small rounded grains of a greenish or brownish colour, but there are also a few larger and more angular individuals of a greenish-blue; these generally show little crystal form, but possess very sharp angles: they have evidently not travelled very far from their source. Zircon is very common and it is very difficult to give a compre- hensive general description, since it shows so much variation; on the whole, however, it may be said that the great majority of the crystals belong to the granitic type of Krushtchov.? They vary much in size, 1 Phillips, ‘‘On the Constitution and History of Grits and Sandstones”’ : Q.J.G.S., vol. xxxvii, p. 17, 1881. 2 Mem. Acad. Imp. Sci. St. Petersb., ser. vil, vol. xliii, No. 3, 1894; Min. Petr. Mitth., N.S., vol. vii, p. 423, 1886. 214 Rk. H. Rastall—Minerals of Lower Greensand. some individuals being as much as 0°38 mm. in length, though most are smaller. Many of them show very fine examples of the spherical and tube-like inclusions described by the above-mentioned author. Apart from these the substance is usually quite clear, and zoned and coloured forms are exceedingly rare. ‘The darger crystals are generally quite sharp, but many of the smaller ones are much rounded. : The hornblende is mostly in the form of rounded and rolled grains, or as much rounded as this mineral is capable of becoming owing to its good prismatic cleavage. The colour is greenish blue, with strong pleochroism, and the mineral is undoubtedly a variety rich in soda, approaching arfvedsonite in composition; it may have come from Scandinavia. Fie. 1.—Kyanite, Sandringham Sands. x 60. The most interesting feature of these specimens is the presence of a considerable amount of garnet, a mineral conspicuously absent from most localities. It occurs both in angular chips and in well-rounded grains, the former being distinctly the larger, and includes both brownish-pink and colourless varieties. ‘The significance of the occurrence of garnet in Norfolk will be dealt with later. 2. SanprincHam Sanps, Castie Risrnc, Norrorx. These specimens were taken some years ago from a sand-pit near Castle Rising, on the west side of the high road from Kings Lynn to Hunstanton. The sand, which is quite loose and incoherent, is pale grey in colour, evidently containing very little iron. A considerable amount of black carbonaceous vegetable material, probably decayed roots, 1s present. A slide of heavy materials prepared from this sample (No. 10641 in the Sedgwick Museum Collection) was figured by Dr. Hatch and the present author.! The slide has been again carefully examined. The principal minerals found were kyanite, tourmaline, staurolite, rutile, with a small proportion of zircon and green biotite. The characteristic and dominant minerals are kyanite and tourmaline, which are both unusually large and well developed. ' Hatch & Rastall, The Petrology of the Sedimentary Rocks, London, 1913, p. 44, fig. 5. R. H. Rastall—Minerals of Lower Greensand. 215 The kyanite occurs in prisms, blades, and shapeless grains, the majority being very little rounded, while some are of very peculiar forms, with conspicuous re-entrant angles (Fig. 1). Tourmaline shows much variation in size, shape, and colour. It is mostly in good crystals of the usual prismatic forms with flat rhombohedral terminal faces; the edges are, as a rule, only slightly rounded, if at all, The ordinary well-rounded drop-like forms are much less common. The commonest colour is a brownish green, with resinous lustre; a few crystals are pure brown. Some more remarkable grains show a brilliant blue colour at the maximum absorption with one nicol prism, while one in particular shows strong pink and blue tints. This is very uncommon. Staurolite is as usual in shapeless yellow fragments, nearly always angular in form, a few only showing traces of crystal-faces. Apart from their unusually large average size there is nothing remarkable about them. Rutile, which is not very common, forms red and orange prisms and grains, small and much worn. A few rounded flakes of green mica are a rather unusual constituent. Zircon is rather rare, only a few comparatively large crystals being seen. The other constituents noted in this specimen are, besides ilmenite, brown, yellow, and red opaque grains, presumably consisting of some oxide ofiron; the treatment with acid seems to have been rather incomplete, as compared with specimens of later date, treated by standardized methods. Other slides prepared more recently from material from the same pit showed all the minerals mentioned above, with in addition a few crystals of dark-green and bluish hornblende, and colourless and pale-green pyroxene, together with flakes of muscovite. One specimen is specially interesting, since it contains a considerable number of rather large grains of garnet, varying from colourless to brownish pink, some being much rounded, while others are very sharply angular and of remarkable forms. These angular chips of garnet are characteristic of many sands of later geological date in the east of England,’ though it would be hazardous to assume that these were derived from the Sandringham Sands or Carstone. One sample from this locality was sufficiently clean and free from iron to be separated and mounted without any preliminary treatment by acid. The chief object of this special examination was to determine the presence or otherwise of minerals soluble in acid, such as might be missed in the ordinary ferruginous samples. This specimen yielded some interesting minerals. Tourmaline was remarkably abundant, most of the grains being brown in colour, but a few were bright blue and one of a clear rose-red. The grains are partly of the usual rounded type, but some are sharply angular, suggesting recent derivation from the parent rock at no great distance. Kyanite and staurolite are common and show nothing unusual; zircon is rather rare, while rutile occurs frequently both as the usual shapeless bright red grains and as clear prisms with 1 Rastall, ‘‘The Mineral Composition of some Cambridgeshire Sands and Gravels’’: Proc. Camb. Phil. Soc., vol. xvii, pp. 136, 138, etc. 216 R&R. H. Rastall—Minerals of Lower Greensand. lamellar twinning: these are of a very deep red colour. Bluish- green hornblende and various pyroxenes, probably including both rhombic and monoclinic varieties, are frequent. Only one undoubted crystal of apatite was found: this is of the usual prismatic form, showing high refractive index, weak birefringence,straight extinction, and negative optical character. The surface shows the usual speckled appearance of this mineral. The presence of several other minerals was suspected though not definitely proved, including anatase, sillimanite, and barytes. Only one crystal of each was seen, and the determinations could not in any case be made with certainty. The horse-shoe magnet extracted nothing from this sample, so that magnetite is absent and even ilmenite is by no means abundant. No garnet was found. When compared with specimens from localities to the west of Cambridge all these samples from Castle Rising are notable for the much larger size of the heavy mineral grains, which also show more pronounced angularity. 3. Ky. The Lower Greensand covers a considerable area around the city of Ely, forming the capping of the higher ground of the ‘‘island”’. The beds are certainly very thin, perhaps not more than 9 or 10 feet, although it is not certain that this is the whole original thickness, since part may have been removed by recent denudation. For the most part they consist of a rather ferruginous sandstone or pebbly grit, which in places become conglomeratic. This is the general character of the rock as used for building stone around the cathedral and elsewhere. The specimens selected for examination came from the well-known exposure in Roswell Pit. This particular band isin a highly inclined position and has certainly slipped. It is in places a good deal weathered and decomposed to soft and crumbly sandstone, but the fresher portions form an unusually good example of a calcareous sandstone, with a cement of crystalline calcite. A sample of the soft weathered sandstone, when broken up and washed, is found to consist of fairly large and rather angular grains of quartz, with a large number of grains or small pebbles of ferruginous and cherty rocks, lydianite and other allied types. The quartz grains are estimated roughly to constitute about one-half of the total. The heavy minerals in separated samples do not show a great amount of variety, but there are one or two special points of some interest. The characteristic, and in fact almost the only, constituents are zircon, tourmaline, kyanite, and staurolite, with a smaller amount of rutile. The zircon crystals, which are the most abundant mineral, present no features of any special interest, beyond the fact that most of them are broken: doubly terminated crystals are very rare. Tourmaline is common, the larger crystals being usually bluish, while the smaller ones are brownish or olive-green and much more rounded. Kyanite is quite abundant, both as large angular flakes and as smaller and more rounded grains. Staurolite also occurs R. H. Rastall—Minerals of Lower Greensand. 217 in the usual small angular chips and fragments, which are common, while larger grains are less frequent. Rutile includes the usual deep red prisms as well as orange and brownish varieties. The most interesting feature, however, is the presence of garnet and blue amphibole in exceedingly small quantity : in fact, the typical sample contained only one grain of each. In their characteristic features, shape, size, and degree of rounding these exactly resembled crystals from the sands of Hunstanton and West Norfolk. The significance of this fact will be dealt with later. 4, Great GRANSDEN. This interesting exposure is somewhat difficult to find, as it is situated in a small orchard behind a cottage in the straggling village of Great Gransden, some 3 miles N.E. of Gamlingay. The orchard is really an old quarry, but most of it is now overgrown. On one side, however, the rock.is well exposed and appears to show a very sharp dip of some 40°. It is clear, however, that this is in reality current-bedding.} oro eere Fic. 2.—Zircons, Great Gransden. x 200. The rock here is of a yellowish colour, and rather coarse in texture, some layers being almost conglomeratic, with small and well-rounded pebbles of quartz, chert, and lydian-stone. There is nothing remarkable about these or about the lighter portion of the finer constituents, but the heavy minerals after separation are interesting, and as might perhaps be expected from the generally coarse texture of the rock, they are of fairly large size. In particular, some of the staurolites reach a diameter of 0°5 mm. The most abundant mineral is zircon in numerous varieties, to be hereafter described, while rutile is also very common. Staurolite, though in large pieces, is not very abundant, and the same remark 1 Fearnsides, Natural History of Cambridgeshire (Brit. Assoc. Handbook), Cambridge, 1904, p. 22. 218 R. H. Rastall— Minerals of Lower Greensand. applies to tourmaline. Muscovite is common in small flakes. Among the rarities may be mentioned a very few crystals of orange sphene, a few bits of colourless pyroxene, anda single very angular colourless isotropic fragment, apparently garnet. A large pale-orange flake with slight pleochroism, distinct striations, and straight extinction, is doubtfully identified as brookite, but it may be an unusual form of rutile. A black metallic-looking mineral in prismatic crystals is ilmenite. : ; Zircon is remarkably abundant and shows a great variety of forms. Nearly all the types described by Krushtchov may be recognized, together with a good many intermediate forms. ‘The commonest habit appears to be the square prism with pyramidal terminations, 100, 111, while similar prisms with their edges bevelled by narrow 110 faces are also abundant. In many cases the angle made by the edges of the pinakoid or prism and pyramid can be measured with sufficient accuracy to determine the form. The horizontal edge Fie. 3.—Zoned Crystals of Zircon, Great Gransden. x 200. made by the intersection of 110 and 111 is very rare here, though common elsewhere. Another common type is the square prism terminated by the bipyramid 311, the gneissic type of Krushtchoy. One very remarkable crystal showed a very long prism with 100 and - 110, the terminations being different at the two ends. At one end | 311 is dominant, while the other appears to show a simple pyramid (Fig. 2). However, in these very small crystals with high refractive index, it is difficult to be certain of the forms, owing to the strong internal reflection and the rounding of the edges and corners. Pale- pink and pale-brown crystals, often much rounded and with strongly developed zonary structure, are also very common. According to the latest researches these may be xenotime, which appears to be isomorphous with zircon and even to form parallel and alternating intergrowths with it. These zoned crystals are on the whole more rounded than those without zonary structure. Fig. 2 shows a number of sketches of interesting forms, some with conspicuous inclusions of various kinds, including both crystals and spherical or spheroidal bodies, which Krushtchov believes to be glass, while Fig. 8 shows zoned crystals of zircon or xenotime, one of them being very much rounded by attrition. hk. H, Rastall—Minerals of Lower Greensand. 219 This specimen also contains several interesting forms of rutile, especially those showing twin-lamelle. The colour of the crystals of this mineral yaries from yellow to orange-brown and deep red. One conspicuous elbow twin on the common 101 law is of a quite pale yellow colour, but most are darker than this. Fig. 4a shows a deep-red, rounded crystal with twin-lamelle making an angle of 61° with the prism zone, while Fig. 4d shows a remarkable resem- blance to a crystal figured by Dr. Teall from the Bagshot Sands of Hampstead Heath.* The arrow-head twins there figured have, however, not been observed in the Greensand. It is clear that rutile varies very widely in many of its physical characters, especially in colour and crystallographic development, and its discrimination from the other Ti0, minerals is not always easy, especially in the case of brookite. The latter mineral, however, does not appear to form twins, which are so common and characteristic in rutile. The other minerals from this locality do not show any noteworthy features. 5, GaMLiIneayY. A few years ago the large brick pit at Gamlingay afforded a very good section showing the unconformity of the Lower Greensand on the Ampthill Clay, but it is now a good deal overgrown and obscured. The sands are somewhat ferruginous, fine, and very uniform in texture, without pebble-beds. Fic. 4.—Crystals of Rutile, Great Gransden. x 200. From an examinaticn of washed but unseparated samples it is clear that heavy minerals are unusually abundant here, since specimens mounted without any concentration show a large number of grains of most of the characteristic species. In samples from most other localities it is rare to find more than half a dozen grains in any one slide. The quartz grains vary much in size and shape: some are quite angular, but the majority are more or less rounded, while a few are very round indeed. The characteristic heavy minerals in separated samples are zircon, kyanite, staurolite, tourmaline, and rutile. Zircon is found in many varieties; some are fairly large, having the form of long prisms with the usual inclusions, but the majority 1 Teall, British Petrography, London, 1888, pl. xliv, fig. 4. 220 L. F. Spath—Notes on Ammonites. are rather short and stumpy. Some pinkish zoned crystals enclose what appear to be prisms of rutile. The smaller zircons are generally very well rounded. Staurolite is generally seen as small angular pieces, but afew rather larger grains show well-marked striations, probably due to cleavage. Rutile is common, the orange-red variety being the more abundant in rather irregular but often well-rounded grains. Tourmaline is less frequent than usual, chiefly as the olive- green variety ; one large piece is of a curious brick-red colour. The kyanite is quite normal; there are a few large prisms, but most are rather small, and some unusually wellrounded. Pale-green pyroxene is rare, and no other transparent minerals were identified. Ilmenite is abundant in the usual brilliant black or metallic grains. A pro- longed search did not lead to the detection of either garnet or sphene. _ (To be continued.) ITV.—Nores on AMMONITES. By L. F. SpatH, B.Se., F.G.S. Vv. 4 S an illustration of the difficulties encountered in basing the I classification on some peculiarity of the Ammonoid suture-line the case of the two families Macroscaphitine and Crioceratine may again be referred to, the former of lytoceratid, the latter of hoplitid origin. Distinction between these two families was based on the _ bifid or trifid characters of the first lateral lobe. Hamulina nitida, v. Koenen,’ which shows very nearly equal-sized suture elements, has the trifid first lateral lobe of the type-species of Hamulina, namely H. dissimdlis, d’Orbigny, but the plain shell of the lytoceratid Anahamulina. Hyatt? put the latter into his family Macroscaphitide, but the former, and also the clearly lytoceratid Pretetia, into Ancylo- ceratide, i.e. even into a different sub-order.? But Anahamulona subcylindrica, d’Orbigny, sp., i.e. the type-species itself, has a nearly trifid first lateral lobe, though it is connected through A. Lorioli, Uhlig, sp. (with a sub-bifid first lateral lobe), with typically lyto- ceratid forms. In ornament and coiling also Hamulina resembles certain lytoceratid forms (compare e.g. the various forms of Macro- scaphitine figured by Uhlig‘). Sarasin and Schondelmayer® wrote in this connexion: ‘‘ After having believed, for a moment, that the similarities shown by the 1 Op. cit., p. 396, pl. lii, figs. 3-5. ? In Zittel-Hastman, Textbook of Paleontology, vol. i, pp. 371, 588. ° The inclusion in Macroscaphitine again of Hamulina, withdrawal of Anahamulina, the inclusion of Spiroceras in Crioceratine, and many other alterations introduced by Professor J. P. Smith in the chapter on Ammonoidea in the second edition of Zittel-Hastman’s Textbook of Paleontology (1913), and evidently not based on additional research, cannot be considered improve- ments on Hyatt’s classification. * “ Cephalop.-Fauna d. Wirnsdorfer Schichten’’: Denkschr. d. Math.- Naturw. Cl. d. k. Akad. d. Wiss., vol. xlvi, Vienna, 1883. ° “Etude Monogr. d. Ammon. du Crét. Infér. de Chatel-Saint-Denis,”’ pt. ii: Mém. Soc. Pal. Suisse, vol. xxix, p. 154, 1902. L. F. Spath—Notes on Ammonites. 221 suture-lines of Hamulina and Crioceras might indicate a real relation- ship between these two genera, we have convinced ourselves that we have here a simple case of convergence. The first lateral lobe, which at first sight appears to be trifid in certain forms of Hamulina, is in reality a bifid lobe, deformed by the reduction of its internal branch.” The writer is inclined to doubt, however, whether many of the apparently lytoceratid forms described as ‘‘ Crioceras” by Sarasin and Schondelmayer ‘‘ enter into the great family of Peri- sphinctidee ”’. Here the adult suture-line alone has been utilized and the result is far from satisfactory, but even where the ontogenetic development has been worked out, one special peculiarity of the suture-line cannot always be regarded as proof of even generic affinity. The writer has shown! that, e.g., in Pszloceras and Zragophylloceras the external saddle has throughout ontogeny a monophyllic ending, whereas in Rhacophyliites stella there are two terminal leaflets. It was assumed, therefore, that Zragophylloceras was more nearly related to Psiloceras and what were grouped as Pleuracanthitide? than to the contem- poraneous Lhacophyllites. Apart from the wide separation, geologically, of Zragophylloceras from the Hettangian genera, the fact that not all ‘‘ Rhacophyliites” have a diphyllic external saddle, and the comparative insignificance of these differences in the endings of the external saddle, make it probable that Zragophydloceras must be derived from its Mediterranean Rhacophyllitid contemporaries. On the other hand, the phylloid character of the suture-line shows that these genera as well as Pszloceras are descendants of the great family Phylloceratida, though few families offer such a striking characteristic of the suture- line for classificatory purposes. The variability of the symmetrical or asymmetrical arrangement of the folioles of the lobes and saddles is well illustrated in the sutural development of Polymorphites cf. jupiter given by A. E. Trueman? and also in that of Cymbites globosus, reproduced from Branco for comparison.* In the former the external saddle of stage hf is trifid on one side and bifid on the opposite half of the same suture-line. Similarly the first lateral lobe is unequally developed on the two sides. In Cymbites globosus the first lateral lobe is bifid at first and trifid afterwards, whereas the reverse is the case with the external saddle. Also the first lateral saddle of the last stage and especially _ the second lateral saddle are not monophyllic like the external saddle of the earlier stage, and therefore do not repeat the progressive complication of the saddles in the manner shown by Zragophylloceras Loscombt. But these two sutural developments are instructive from another point of view. The very deep ventral lobe of Cymbites from the third suture onwards shows this genus to be an Arietid, and 1“ The Development of Tragophylloceras Loscombi’’: Q.J.G.S., vol. lxx, 1914. ; > The family Pleuracanthitide, Hyatt em. Diener, provisionally accepted in the paper mentioned above, cannot be upheld. * Op. cit. (G@EoL. MaG., 1917), p. 445, Fig. 10. 4 Loe. cit., p. 447, Fig. 13. 222 L. F. Spath—Notes on Ammonites. geological occurrence and general resemblance suggest, at least for the devigatus group, to which the genus Cymbites should be restricted,' modification of an ‘On the Grouping of some Divisions of so-called ‘Jurassic’ Time’? : Q.J.G.S., vol. liv, pp. 442-62; also in A Monograph of the Ammonites of the ““ Inferior Oolite Series’’, Supplement, Pal. Soc., vols. 1898-1907, p. exeviii. * Traité de Paléontologie, vol. ii, p. 673. L. F. Spath—WNotes on Ammonites. 223 is referred to the old genera ‘‘ Gonzatites’’ or ‘“Ammonites’’, or to a modern small subdivision. For stratigraphical purposes a much more exact definition than in the past of the horizon of each form will be necessary. Here, again, clearness and uniformity of nomenclature, facilitated by a natural classification, would be of great advantage. Since Mr. Lang! has shown that in the case of Deroceras armatum, at. least at Charmouth, there probably is ‘‘ an example of the zonal fossil lying entirely outside the zone that bears its name”, it will be admitted that this revision of the horizons of Ammonites is of importance. Moreover, little value now is placed on specific identi- fications for zoning purposes. With regard to graptolites, Dr. Elles * wrote recently: ‘‘ Detailed knowledge of the different species is in no way necessary for the recognition of the different horizons. The nature and value of a Graptolitic zone depends on the assemblage of characteristic forms.’? And with regard to Ammonites, Mr. Buckman* had stated five years previously that ‘‘one did not ascertain the date of a deposit so much by the actual species as by the general facies, in the case of Ammonites. Coarse-ribbed Dumortierie, fine- ribbed Dumortieri@, Ammonites of aalensis pattern, Opalinoids, showed the dates as well as more exact identifications, because the successive Ammonites of different genera assumed certain develop- mental facies ”’ As important as a revision of nomenclature and horizons seems, to the writer, to be the elucidation of the phylogenetic problems pre- sented by the Ammonites, and the consideration of their evolutionary significance in relation to research done in other branches of modern science. Developmental paleontological research has taken an active part in the establishment of modern evolutionary theories, and with Waagen and Blake* one may consider ‘“‘to have here the true basis of paleontology as an independentscience’’. As Zittel® stated: ‘* The character of palzeontological literature has been correspondingly modified; the purely stratigraphical treatment of paleontological results has been held more and more distinct from the biological systematic treatment, and the latter places the genealogical direction of research more and more in the foreground.”’ Since the Ammonite animal is unknown, many important Heiss of evolution can only be imperfectly inferred and not demonstrated by those structures that alone are preserved to us. The writer would favour, for the fossil forms of Cephalopoda, the division into three main orders, without reference to gills. The Nautiloidea and Belemnoidea are outside the scope of the present paper; with regard to the Ammonoidea, the division into ‘‘Ammonitide’’ and ‘‘Goniatitide”’ is, of course, as little justified as was the original 1 “The Geology of the Charmouth Cliffs, Beach, and Fore-shore’’: Proc. Geol. Assoc., vol. xxv, p. 321, 1914. 2 Proc. Geol. Assoc., vol. xxvi, p. 267, 1915. > ** Certain Jurassic [Lias—Oolitic] Strata of South Dorset, and their Correlation’’: Q.J.G.S., vol. lxvi, p. 53, 1910. 4 “*The Evolution and Classification of the Cephalopoda, an Account of Recent Advances ’’: Proc. Geol. Assoc., vol. xii, p. 278, 1892. ° History of Geology and Paleontology, London, 1901, p. 380. i) 24 L. F. Spath—Notes on Anvmonites. grouping by von Buch into the three sections of Goniatites, Ceratites, and Ammonites, or, by Wright, into three corresponding families. As the discovery of rich Triassic faune showed the impossibility of separating the Ceratites from the Ammonites, so the interesting Permian forms dealt the death-stroke to the division into Ammonitids and Goniatitids. Professor Haug! stated already in 1894 that ‘¢a classification of Ammonoidea into Goniatites and Ammonitids, or into Retrosiphonates and Prosiphonates, would not be really natural, except if all were descended from a single Goniatite family. Permian Ammonites showed, however, that several families were evolved, more or less in a parallel manner, and passed through the Goniatite into the Ammonite stage’’. Thus, complication of the suture-line, change of the protoconch from latisellate to angustisellate, and modification of the septal necks took place in the different stocks of ‘‘Goniatites’’ that persisted into the Permian and Triassic periods, at different times; and since it is possible that the Goniatites themselves did not originate from one single Nautiloid stock (for in the Devonian several very distinct groups can be recognized) it is clear that the subdivision of Ammonoidea into Goniatites and Ammonitids cannot be upheld. Haug, in his admirable textbook,? indeed, divides the Ammonoidea from the Devonian onwards into several great ‘‘phyla’’: Anarcestide and Glyphioceratide (the latter with many ‘Triassic families), Agoniatitide, Prolecanitide (with Ceratitide), and Gephyroceratide. This last ‘‘ phylum” includes the Phylloceratidze and is therefore the root-stock of the host of the Jurassic and Cretaceous Ammonites. The writer® had to differ from Haug on this latter point and also from that author’s interpretation of the genera WVomismoceras, Dimorphoceras, and Thalassoceras,* and there can be no doubt that a good deal of research is necessary yet before this classification of Haug’s can be said to rest on a secure foundation; but it marks a splendid advance in the right direction. The same cannot be said for the three ‘‘phyla” Belocerata, Tomocerata, and Gephyrocerata, proposed in his work on the Triassic of Albania by G. v. Arthaber.® These ‘‘ phyla’’, widely separated already in the Devonian, are ‘‘assemblages of heterogeneous elements’’, as Diener® has already pointed out, and show the greater value, for classification of the larger groups, of the suture- line compared with other characters. The Liassic and later families of Ammonites are then looked upon, not as being subordinate to a sub-order ““Ammonitide’’ of the order Ammonoidea, but as being, with some Triassic groups, 1 “*Ties Ammonites du Permien ef du Trias’’: Bull. Soc. Géol. France, ser. III, vol. xxii, p. 386. 2 Traité de Géologie, vol. ii, fasc. 1, 2, Paris, 1908-11. 3 Op. cit., 1914, p. 353. 4 Op. cit., vol. ii, fase. 1, pp. 754-5. Beitr. z. Geol. u. Palaeont. v. Oesterr.-Ung., etc., vol. xxiv, 1911. 5 Triassic Faune of Kashmir (Mem. Geol. Surv. India), N.S., vol. y, i, p. 3, 1913. ao I. F. Spath—WNotes on Ammonites. 225 subordinate to the super-family Phylloceratida, which, like the earlier and probably ancestral super-family Glyphioceratida, belongs to some great ‘“‘phylum” ranging up from the Devonian. These four or five stocks or ‘‘ phyla”, of which one at least begins already in the Silurian, and only one of which transgresses the Trias—Jura border, comprise for convenience the order Ammonoidea. In tracing these ‘‘ phyla”, based so far mainly on the adult suture-line, stress will have to be laid on the ontogenetic develop- ment, as has already been pointed out. Branco,'! as far back as 1879-80, had dissected sixty-four species of Ammonites; but with a few exceptions, among which Professor J. Perrin Smith’s paper on the ‘‘ Development of Lytoceras and Phylloceras’’ * may be mentioned, observations on the less obvious features such as the earliest chambers and the gradual development of the various characters, were neglected by paleontologists. When Michaelski in 1890,° relying on the differences in the ornament of the inner whorls of the various species of so-called Virgatc, separated these into the two genera Olcostephanus and Perisphinetes, he met with opposition, at first, even from A. Pavlow,‘* who wrote, ‘‘ The older specimens have absolutely the same type of suture and are so much alike in shape and ornament that it is extremely difficult to distinguish them if the ontogenetic development of each cannot be studied.” Since then, practically on differences in shape and ornament of the adult shell alone, some twenty new genera have been created for various forms formerly included in Perisphinctes, but the ontogenetic development of most of them is still unknown. ‘The writer’s personal research has been connected chiefly with Lias Ammonites, and the study of the ontogeny of most of their principal types has now been concluded. The phylogenetic conclusions arrived at differ con- siderably from the interpretations of the relationship of these Ammonites given by other authors, and prove that until the development of the more important types at least of other periods as well has beer studied in detail, there seems little hope of arriving at a satisfactory classification of Ammonoidea. In conclusion, the writer would like to express his obligation to all those who have helped him with material for research or with valuable suggestions. His thanks are especially due to Dr. A. Smith Woodward, the late Mr. G. C. Crick, and Dr. W. D. Lang, of the British Museum (Nat. Hist.); also to Dr. Wyatt Wingrave, Dr. A. Morley Davies, and Mr. C. P. Chatwin. “Beitr. z. Hntwicklungsgeschichte der Fossilen Cephalopoden ”’ : Paleontographica, vol. xxvi, pts. i, ii, 1879. 2 Proc. Calif. Acad. Sci. [3], i, 1898. 3 **Die Ammoniten der Unt. Wolga-Stufe’’: Mém. du Comité Géol. St. Pétersbourg, vol. viii, No. 2. 4 In Paylow & Lamplugh, Argiles de Speeton, etc., Moscow, 1892, p. 114. DECADE VI.—VOL. VI.—NO. V. 15 226 Some Recent American Petrological Literature, V.—Some Recent American PerroLocicaL LITERATURE. (Continued from p. 179.) ‘‘The Igneous Geology of Carrizo Mountain, Arizona,” by W. B. Emery. Amer. Journ. Sci., vol. xlii, pp. 849-63, 1916. This region includes various intrusive bodies : Nets sills, dykes, and a large laccolith of diorite-porphyry. The presence of six ~volcanic plugs also indicates extrusion, though all flows have been removed by erosion. ‘Contributions to the Geology of Java and Celebes,” by J. P. Iddings and E. W. Morley. Journ. Geol., vol. xxiii, pp. 231— 45, 1915. The rocks from Java described in this paper include leucite-tephrite, leucitophyre, shoshonite, basalt, and varieties related to kentallenite and borolanite. Those from Celebes comprise nepheline-syenite, kentallenite, trachyte, and marosite. Full petrographical descrip- tions and analyses are given. ‘‘Contributions to Sardinian Petrography. I. The Rocks of Monte Ferru,”? by H. 8. Washington. Amer. Journ. Sci., vol. xxxix, pp. 013-29, 1915. A detailed petrographical description, with analy ses, of certain trachytes, phonolites, basalts, and analcite basalts from this well- known locality. . ‘‘Primary Analcite of the Crow’s Nest Volcanics,” by J. D. Mackenzie. Amer. Journ. Sci., vol. xxxix, pp. 571-4, 1915. A reply to criticisms on some previously published work, the point at issue being as to whether the analcite is primary, or formed by alteration of leucite by sodium solutions in salt lakes. ‘‘Relation of Ore Deposits to different types of Intrusive Bodies in Utah,” by B.S. Butler. Econ. Geol., vol. x, pp. 101-22, 1915. The ore deposits associated with laccoliths and more deeply truncated stocks are of little commercial importance, while those connected with apically truncated stocks are of great value. This is attributed to the concentration of mobile metal-bearing vapours or solutions near the apex of the stocks, in which differentiation was more complete than in the laccoliths. In the case of the more deeply truncated stocks the metalliferous portion has been removed by erosion. ‘“The Ternary System MgO-Al.03-SiO2,” by G. A. Rankin and H. E. Merwin. Amer. Journ. Sci., vol. xlv, pp. 301-25, 1918. The temperature-concentration relations of ee ae phases in equilibrium with liquid are discussed and represented by diagrams and amodel. A ternary compound, 2Mg0.2A1203.58102, was found in two forms with a transition point at about 950°C. It is very like cordierite. The effects of FeO on magnesian minerals and rocks are also considered. Some Recent American Petrological Interatwre. 227 “The Ternary System CaO-MgO-Si02,” by J. B. Ferguson and H. KE. Merwin. Proc. Nat. Acad. Sci., vol. v, pp. 16-18, 1919. A very brief summary of a hitherto undescribed portion of this system by the quenching method. The phases found include, among others, cristobalite, tridymite, pseudowollastonite, periclase, forsterite, monticellite, diopside, and various solid solutions. One hitherto unrecorded compound is probably akermanite. The temperature- concentration relations are shown in a triangular diagram. “Temperature Viscosity Relations in the Ternary System CaO- AlsOs—Si0,,” by A. L. Field & P. H. Royster. Trans. Amer. Inst. Min. Eng., vol. lviui, pp. 658-68, 1918. A study of the viscosity of slags, with reference to blast-furnace work. Measurements of viscosity show the existence of definite compounds in slags and even indicate their fields of stability. The maxima of viscosity occur at quintuple points and the minima at the binary eutectics. ‘The Significance of Glass-making Processes to the Petrologist,” by N. L. Bowen. Journ. Wash. Acad. Sci., vol. viii, pp. 88-93, 1918. . Observations during war-work at the Bausch-Lomb glass plant are applied to elucidate inhomogeneity in silicate melts. Liquid immiscibility and the Gouy-Chaperon principle are regarded as inapplicable, and differentiation is referred to rising of crystals and sinking of heavy liquid. ‘© A Type of Igneous Differentiation,” by F.F. Grout. Journ. Geol., vol. xxvi, pp. 626-58, 1918. The rocks of the Duluth intrusions fall into two series, gabbroid and granophyric (red rock). The evidence suggests an immiscible separation of acid and basic portions, the variations in the gabbro being produced by convection. The evidence is strong that differentiation of two kinds may occur in a single magma-chamber. ‘“The Lopolith: an Igneous Form exemplified by the Duluth Gabbro,”’ by F. F. Grout. Amer. Journ. Sci., vol. xlvi, pp. 016-22, 1918. The Duluth gabbro differs from typical laccoliths in that its central part is sunken, not raised. It is about 140 miles across, covering an area of about 15,000 square miles, and its volume is estimated at 50,000 cubic miles. It is intruded along the base of the Keweenawan. It is compared to the igneous masses of Sudbury and the Bushveld, and possibly of Skye and Julianehaab. For such saucer- shaped masses the name “ lopolith”’ is suggested. “The Charnockite Series of Igneous Rocks,” by H. 8S. Washington. Amer. Journ. Sci., vol. xl, pp. 8323-88, 1916. Analyses, supplementary to Holland’s descriptions, are given of five specimens of typical rocks of the Charnockite series, selected by the Indian Geological Survey. ‘The relations of the Charnockites to the rocks of similar petrographic provinces are discussed somewhat fully. 228 Some Recent American Petrological Literature. ‘‘Geological Observations in Fiji. Part Il: Petrography of Fiji,” by W.G. Foye. Proc. Amer. Acad. Arts and Scei., vol. liv, pp. 97-145, 1918. Petrographic descriptions are given of a large number of rocks collected by the writer in the ‘islands of the Fiji group. They include tonalite, gabbro, porphyrite, pitchstone, andesite, basalt, and various pyroclastic types. Besides the plutonic intrusions four periods of extrusion are recognized, grading from acid to basic, all types being subalkaline and probably differentiates of a basaltic magma. ‘‘The Nepheline Syenites of Haliburton County, Ontario,” by W. G. Foye. Amer. Journ. Sci., vol. xl, pp. 413-86, 1915. A petrographic description of two differentiated laccoliths of nepheline syenite, together with a discussion of the origin of such rocks in general: it is supposed that the solutions that gave rise to them were produced by the reaction of limestone with granitic magma. ‘‘Kruptive Rocks at Cuttingsville, Vermont,” by J. W. Eggleston. Amer. Journ. Sci., vol. xlv, pp. 377-410, 1918. This small complex includes a large number of alkaline types ranging from essexite to nordmarkite, with their accompanying apophysal and complementary dykes. They are very similar to the rocks of Mount Ascutney, Red Hill, and Essex County in New England, and to the bosses of the Monteregian province, Quebec. “‘The Origin of Serpentine: a Historical and Comparative Study,” by W.N. Benson. Amer. Journ. Sci., vol. xlvi, pp. 631-781, 1918. Chrysotile and antigorite serpentines are alteration products of peridotites, more or less pyroxenic; the hydration being often brought about by waters from the same magma. Sometimes it is due to water from later intrusions or to the general underground circulation. An extensive bibliography of serpentine is appended. ‘‘Magmatic Differentiation in Effusive Rocks,’’ by S. Powers and A.C. Lane. Trans. Amer. Inst. Min. Eng,, vol. liv, pp. 442-57, 1917. An investigation of gravitative differentiation - phenomena in effusive rocks shows a concentration of leucocratic minerals near the top and of melanocratic minerals near the base of the flows, while chilled margins show the original composition. ‘‘ Triassic [gneous Rocks in the vicinity of Gettysburg, Pennsylvania,” by G. W. Stose and J. V. Lewis. Bull. Geol. Soc. Amer., vol. xxvii, pp. 623-44, 1916. Subsidence and faulting of Triassic sediments was followed by intrusion of prevalently diabasic magma, its products ranging from olivine diabase through hypersthene diabase to quartz SIE E or even nearly pure quartz-felspar micropegmatite rocks. Reviews—Les Echinides des “ Bagh Beds”. 229 ‘“« Hypersthene Syenite and Related Rocks of the Blue Ridge Region, Virginia,” by T. L. Watson and J. H. Cline. Bull. Geol. Soc. Amer., vol. xxvii, pp. 1938-234, 1916. This petrographic province, which is probably of pre-Cambrian age, comprises a batholith about 150 miles long by 20 miles wide, composed of differentiates of a syenitic magma; the chief types are quartz-hypersthene syenite, granite, norite, gabbro, pyroxenite, and a quartz-felspar-epidote rock. ‘‘ Zircon-bearing Pegmatites in Virginia,” by T. L. Watson. Trans. Amer. Inst. Min. Eng., vol. lv, pp. 936-42, 1917. Pegmatites from Amelia County contain zircon, with beryl, helvite, allanite, columbite, and monazite, while those from Hanover County are specially characterized by zircon and rutile. “The Emerald Deposits of Muzo, Colombia,” by J. E. Pogue. Trans. Amer. Inst. Min. Eng., vol. lv, pp. 910-34, 1917. _ A detailed description of the emerald deposits and their associated minerals with an account of the present state of the mining industry. The origin of the emeralds is ascribed to mineralization associated with intrusion of pegmatites. REVIEWS. J.—Lers Ecuinipts pes ‘‘ Bago Beps”. By R. Fourtrav. Records Geol. Surv. India, vol. xlix, pt. i, pp. 34-53, pls. i, 11, 1918. IJ\HE age of the marine Cretaceous series of the lower part of the Narbada Valley, generally known as the Bagh Beds, has long been regarded as Cenomanian, a view based to a large extent on Duncan’s researches on the Kchinoids. Other views of their age have been expressed, notably those of Stoliczka and of Bose, who both considered that more than one Cretaceous horizon was represented. At the time of Duncan’s writing the Echinoids were the only group of fossils from these beds that had been critically examined, but Mr. E. W. Vredenburg has since studied the Ammonites, although he found that they did not help in determining the exact age of the beds. The specimens upon which Duncan based his conclusions have lately been re-studied by M. R. Fourtau, whose results are valuable ~ because they determine more accurately the relationships of these Echinoids, and also fix the age of the beds with more certainty. Duncan was so convinced by the general facies of the Echinoids that he was dealing with an undoubted Cenomanian fauna, that he did not find it necessary to make comparisons with olderforms. M. Fourtau, on the other hand, was much puzzled by the record of two of the species, Salenia fraast and Echinobrissus goybeti, since they belong to an horizon which R. P. Zumoffen has recently shown to be synchronous with the Aptian of the Mediterranean border. He has therefore made comparisons with a wide range of species in the Cretaceous, and he concludes that the Echinoids have affinities with the Early and Middle Cretaceous forms, that the Bagh Beds are of 230 Reviews—Coal of Pallasca, Huaylas, and Yungay. Albian age, and that only one horizon is represented in the series. He thinks that the presence of Placenticeras mintor, Vredenburg, confirms the reference of the beds to the Albian stage, since this Ammonite is related to P. uhligi, Choffat, from the Bellasian of Portugal, and to P. saadense, Peron & Thomas, from the Vraconnian ot Northern Africa. M. Fourtau gives a careful description of the eight species found in the Bagh Beds. He identifies Duncan’s Cidaris namadieus [ sic; the termination should be feminine] asa true Dorocidaris. In the case of Salenia fraast the original diagnosis by Cotteau was not precise, hence later workers were misled, but M. Fourtau now shows that the form from the Bagh Beds is not the same as that from the Aptian of Lebanon. The new name S. keatingei is proposed for the species described by Duncan, which is regarded as closely comparable with S. mamuillata, Cotteau, from the Aptian of France. The Cyphosoma from the Bagh Beds, which Duncan determined as C. cenomanense, Cotteau, is now ealled C..namadicum, n.sp.,and the nearest related speciesis C. peront, Cotteau, from the Barremian of France and Switzerland. The name Orthopsis indica, Duncan, still stands; the species is now compared with O. repellini, Desor, from the Barremian and Aptian of France, Switzerland, and Portugal. M. Fourtau regards the two large specimens of Hehinobrissus goybett, Duncan non Cotteau, and the two. small deformed £. similis, Duncan non d’Orbigny, as of the same species, and proposes the new name &. haydeni. The nearest allied species is ZL. eddissensis, Gauthier, from the Aptian and Albian of Algeria and Tunis. Hemiaster cenomanensis, Duncan non Cotteau, is redescribed as HZ. oldhami, n.sp., and the most closely related species is H. luynesi, Cotteau, from the Cenomanian of Palestine. Other examples of Hemiaster were referred by Duncan to A. similis, Orbigny, of which a figure was subsequently reproduced by Mr. R. D. Oldham in his Geology of India. Of the five specimens sent to M. Fourtau, three are separated and. described as Opisaster subsimilis, n.sp., and regarded as related to O. morgani, Cotteau and Gauthier, from the Senonian of Persia. The other two are described as Opisaster, sp. indet., a form related to O. vignesi, Cotteau, from the Cretaceous of Palestine. CoE: T1.—Yacntrentos CarponiFeRos DE LAS Provrnoras DE PaLrasca, Hvuaynras y Yuneay. By Juan M. YaNez Leon. Boletin del Cuerpo de Ingenieros de Minas del Peru, No. 90, pp. 85, with 5 plates and 2 maps. 1918. (W\HE stoppage of the import of foreign coal into Peru has served to call attention to the potential value of native supplies, and in this memoir the author gives an account, both scientific and economic, of the large supplies of high-grade coal that exist in the provinces of Pallasca, Huaylas, and. Yungay. The coal occurs in strata of Lower Cretaceous (Wealden) age, forming three seams averaging about 1, 2, and 1 metres respectively, separated by varying thicknesses of sandstones, shales, and limestones. As shown by the sections given the strata are considerably folded, and Reviews—The Mineral Resowrces of Great Britain. 231 in some localities the dips are as high as 60°, though over a considerable area the beds are nearly flat. The coal is of anthracitic character, averaging about 79 per cent of fixed carbon, 10 per cent of volatile matter, and 6 per cent of ash, with a calorific, power of about 138,770 B.T.U. It is of good quality, well suited for industrial uses, although possessing poor coking properties. A highly conservative estimate gives a workable quantity of 152,900,000 tons, allowing an abundant margin for all contingencies in working. A brief account is also given of the tungsten ores of Huaura, and of a newly discovered region in the neighbourhood of Tarica, as well as of the copper deposits of Magistral. Daya dele de I1I.—Sprcrat Reports on THE Mtnerat Resources oF Great Brirary. Vol. VIL: Lienrres, Jers, Kimmertper O1n-sHaLe, Minera O11, CanneL Coats, Narurat Gas. Part I: Enetanp anp Wates. By A. Srranan. Mem. Geol. Survey, pp. 69, with 1 plate and 8 text-figures. 1918. Price 2s. 6d. URING the last four years there has been a vast amount of irresponsible talking and writing about the possibility of the discovery of workable sources of oil and other natural fuels, other than coal, inthe British Isles. It is, therefore, highly satisfactory to find that the Geological Survey has collated all known information on the subject, examining the records of past operations so far as available, and in the case of present explorations, carrying out independent investigations on the spot. The scope of the Memoir is sufficiently indicated by its title. The most important sections deal with the lignites of Bovey Tracey, the explorations made in them by Germans and others, and the uses to which they have been put; the distribution of Kimmeridge Oil-shale throughout the country; the principal known occurrences of mineral oil, cannel coal, and natural gas. It may be said at once in general terms that a careful perusal of this volume does not lend any notable amount of support to the highly optimistic views set forth in the daily papers during the last year or two. A very full description is given of the well-known lignite and clay deposits of Bovey Tracey, and of the somewhat obscure operations of the German company, which mysteriously vanished two days before the declaration of war. It appears that the products of their industry were not of satisfactory quality, owing to the fact that the lignite consists mostly of highly resinous Sequoia wood, which seems to be unsuitable for the manufacture of paraffin wax and similar materials; the chief product of distillation being an evil-smelling yellow tar, a wholly unsaleable substance. Detailed sections are given of several borings put down in this area ; these show the presence of a large amount of lignite, which is apparently only of poor quality and much mixed with clay. It is also shown that lignite has a wide distribution in Tertiary, Cretaceous, and Jurassic rocks, but nowhere in workable quantities. A brief account is given of the almost extinct Whitby jet industry. 232 Reviews—Ooal, etc., in the Netherlands. A chapter of seventeen pages is devoted to a consideration of the Oil-shales of the Kimmeridge series, which have lately been the subject of much discussion. The observations here recorded are largely founded on the results of borings made by the Department for the Development of Mineral Resources. The possible oil-yielding bed, locally known as the ‘‘ Blackstone’’, forms part of the upper division of the Kimmeridge, and was probably never laid down over much of the distance between Dorset and Cambridgeshire, coming in again as bituminous shales in Lincolnshire and Yorkshire. Numerous analyses are given of samples from Kimmeridge and Corton, in Dorset, and from Donnington-on-Bain, in Lincolnshire. The yield of oil varies from 13 to 39 gallons per ton, and of sulphate of ammonia from 11 to 32 lb. per ton in Dorset, the figures for Lincolnshire being much lower. ' The well-known occurrence of natural gas at Heathfield, in Sussex, is described, as well as other instances met with in borings at Calvert, in Bucks, and near Middlesbrough, which appear to be unimportant. From a statement in the preface it appears that this memoir is to be regarded as an instalment, and that a further publication on the subject of mineral oil in Britain is in contemplation. RHR TV.—EINDVERSLAG OVER DE ONDERZOEKINGEN EN UITKOMSTEN YVAN DEN Dienst peR RisKsopsporine VAN DrLrsrorren IN NEDERLAND, 19038-1916. 664 pp. Amsterdam, 1918. f[\HIS immense volume contains the final report on the investigations that have been carried on in the Netherlands in search of coal and other useful minerals, chiefly under the direction of Mr. W. A. J. M. van Waterschoot van der Gracht, a geologist well known in England. In 1903 the Government made a grant of 3,000,000 gulden for this purpose: the total cost for 25 deep bores and all expenses was about 2,500,000 gulden. Coal-measures were actually reached in three areas: (1) In the Peel district in the middle and north of Limburg coal was proved at a less depth than 1,200 m. over an area of 19,500 hectares; it is estimated that seams of workable thickness contain 1,766,000,000 tons, while a further 799,000,000 tons below 1,200 m. may possibly be workable in the future, though not immediately available. (2) In the Winterswijk district in East Gelderland 300,000,000 tons of coal exist at depths not greater than 1,400 m., and an enormous amount of rock-salt was also proved. (3) The most important coalfield is, however, in South Limburg, where coal occurs at a less depth than 1,200 m. over an area of at least 37,000 hectares. The coal is classified according to its gas content, in the German manner, and the reserves are estimated as follows :— Tons. Over 35 per cent gas content . . 206,000,000 35-30 ,, ah 483,000,000 30-20 ,, 4 1,396,000,000 20-14 ,, Me 927,000,000 below 14 al Ne 1,541,000,000 . 4,553,000,000 Reviews—Aquamarine Mines in Baltistan. 233 Hence the whole coal reserves of the Netherlands, probably workable under present engineering and economic conditions, amount to 5,256,000,000 tons, without taking into account supplies that may become available at a later date. In the Buurse-Hengele district in the south-east of Overijssel, the coal was found to lie too deep, but important beds of rock-salt were encountered. The vast deposits of salt found both here and in the Winterswijk district suggest the possibility of finding both potash salts and petroleum. The report gives a detailed account of the stratigraphy and paleontology of the beds passed through by the borings, the paleo- botany being dealt with by Dr. W. J. Jongmans. The local development of the strata is carefully compared with those seen in France, Belgium, and Westphalia. The Upper Carboniferous is divided into four groups, respectively designated the Maurits, Hendrik, Wilhelmina, and Baarlo stages, in descending order. Each of these appears to be characterized by a special assemblage of fossil plants. The whole investigation affords an admirable example of far-seeing and well-directed enterprise, and both the Government and the staff employed are to be congratulated on the results obtained, which seem likely to lead to important commercial developments in the near future, possibly rendering Holland economically independent of foreign supplies of coal. The sufferings of the country in the last four years will doubtless stimulate efforts in this direction in view of a possible repetition of such conditionsin the event of a future war. Jee ly aac V.—Nore on rae Aguamartne Mines or Daso, Barrisran. By C. S. Mipptemiss and L. G. Parswap. Rec. Geol. Sury. India, vol. xlix, pt. iil, pp. 161-172, with 5 plates, 1918. | to 1915 an important deposit of aquamarine was located at Daso, on the Braldu River, Shigar Valley, Baltistan, Kashmir, and it is now being actively exploited. The country rock for miles round is biotite-gneiss with big veins of coarse pegmatite, consisting of quartz, orthoclase with some albite, tourmaline, muscovite, garnet and beryl. The best and most transparent beryls are found in drusy cavities, and the prisms are often up to 3 inches long, while crystals of opaque varieties may be as much as 6 inches in length. The colour of the best specimens is not very deep, but of the true aquamarine shade. The available supply appears to be very large, but mining is somewhat handicapped by high transport charges for stores and equipment. VI.—Osservactones Gxotdeicas EN La Ista DE Gomera (Canarias). By L. F. Navarro. Trab. Mus. Nac. Cien. Nat., Geological Series No. 23, pp. 87, with 34 text-figures and a map. - Madrid, 1918. . fae author has paid several visits to this little-known island, of which he describes the topography and geology in some detail. The island is remarkable for the abruptness of its shores and the general steepness in its slopes. It is deeply dissected by a large number of 234 Reviews—Basalts from Southern Patagonia. ‘‘barrancos’’, steep valleys of characteristic form with passes at their heads affording means of access from one part of the island to another. The author also discusses with particular care the origin of the peculiar isolated peaks and platforms of phonolite, locally called ‘‘roques”’ and ‘‘fortalezas”’, and discourages the tendency to explain them all without discrimination as spines of the Peléan type, although admitting that a few of them may be such. Petrographic descriptions are given of the rock-types observed, which include augite-andesite, basalt, cegirine-phonolite, trachy- phonolite, trachyte, sanidinite, and trachyandesite, with corresponding tuffs and breccias. i. ie VIJ.—PrrrocrapuiscHe BuscHRErBUNG FINIGER BasaLte von Pata- GONIEN, WESTANTARKTIKA UND DEN Sip-Sanpwicu Insetn. By 0. Bancxsrrom. Bull. Geol. Inst. Univ. Upsala, vol. xiii, pt. ii, p. 115, 1916. ay elaborate petrographical description of basalts from various localities in Southern Patagonia, from Ross Island, Cockburn Island, Paulet Island, and other localities in the western part of Antarctica, together with the South Sandwich Islands. The general characteristics of most of the area described are somewhat indefinite from the petrographic point of view, since calc-alkali basalts are widely distributed, but commonly associated with rocks of distinctly alkaline and Atlantic type. In the South Sandwich Islands, how- ever, alkaline rocks are wholly wanting, indicating a connexion with the calc-alkaline Pacifie province. VIII.—Scorr anp Stenirrcance or Patxo-rcotogy. By Freperic E. Crements. Bull. Geol. Soc. Amer., vol. xxix, pp. 3869-74. June 30, 1918. HE title of this paper is promising, but the performance is un- satisfying. ‘‘ Paleo-ecology,”’ says the author, ‘‘is characterized by its great perspective, due chiefly to the absence of a large body of facts.” The meaning of this is obscure, unless it is that the wood is easily seen because there are so few trees. The author’s chief points, so far as we can extract them from an abundance of words, are that vegetation should first be studied because it is the connecting link between the topography and the fauna; secondly, that valuable results may be expected from the study of successive floras and faunas in a limited area. It will be gathered that Mr. Clements’ attention is focussed on epi-continental formations (forgive the mongrel term!), such as the badlands and lacustrine deposits of North America. From there some interesting facts and inferences are cited. ; IX,—Mivneratocy or tae H.B. Mine, Sarmo, B.C. By T. L. Watxer. University of Toronto Studies, Geol. Ser., No. 10, 1918. HE minerals, calamine, spencerite, hopeite, and parahopeite, formed by the oxidation of zinc.ores in a marmorized limestone are described. From an examination of the optical properties Reports & Proceedings—Geological Society of London. 235 spencerite had previously (In. Mag., 18, 76, 1916) been classed as monoclinic, and this is now confirmed by goniometrical measurements. he relationships of the various hydrated zine phosphates are briefly discussed. IRD X.—Nores on Mrwerire, THavmasitz, and Wavetnitn. By E. T. Wuerry. Proc. U.S. Nat. Mus., 34, 373-81, 1918. ee crystals of mimetite described are of unusual habit and rich informs, several of which are new. A ‘‘prism”’ determination of the mean refractive index gives the value 2°14, agreeing with previous values obtained by the immersion method. New forms were also observed on thaumasite, which is regarded by the author as a sulphate. Wavellite rarely occurs in measurable crystals, but in this instance the development is sufficiently good for the crystals to be measured, the axial ratios being 0°345:1:0°404. The refractive indices and chemical composition are also determined. ASS XJI.—Averre From Srromporr. By S. Kozv and H. S. Wasuineton. Amer. Journ. Sci. (4), 45, 468-9, 1918. ae results of chemical and optical examinations of the augite, occurring in the ashes round Stromboli, are given. In chemical composition it closely resembles other Mediterranean augites, as 80 per cent consists of the diopside molecule, the remaining mole- cules being acmite, hypersthene, and an aluminous compound in nearly equal proportions. he refractive indices for sodium light are, a 1°6938, 8 1:699, y 1:719, while the optical axial angle (2V) is 57° 39, ACS: XII.—Uniren Sratzs Nationat Museum. (JVHE annual report on the United States National Museum for the year ending June 30, 1917, published by the Smithsonian Institution, includes an account of the additions made to the Depart- ment of Geology during that time. The Department was specially fortunate in the acquisition of meteorites, having received by bequest the well-known and important Shepard Collection. Other noteworthy accessions were specimens of ores of metals used for hardening steel, namely tungsten and vanadium. A large number of good mineral specimens and gem-stones were transferred from the Geological Survey, and the paleontological collections were enriched by the addition of a large number of type-specimens. RHPORTS AND PROCHEDINGS.- I.—Gerotocican Soctery or Lonpon. 1: Parts of the Report of the Annual General Meeting on February 21, 1919, having already appeared in the GuorocicaL Macazine (see March Number, pp. 97, 98, and April Number, pp. 145-6), it is obviously needless to repeat them in further detail here.—Epr70R. 236 Reports & Proceedings—Geological Society of London. 2. February 26, 1919.—Mr. G. W. Lamplugh, F.R.S., President, in the Chair. The President said in accordance with the Special Notice it was proposed to change the subject previously announced for the after- noon’s meeting, and he hoped the change would be approved, namely, that Colonel T. W. Edgeworth David, D.S.0O., C.M.G., D.Sc., F.R.S., would deliver a lecture on ‘‘Geology at the Western Front’’. After the lecture a vote of thanks was unanimously accorded to Colonel David for his lecture. 3. March 12, 1919.—Mr. G@. W. Lamplugh, F.R.S., President, in the Chair. The following communication was read by Mr. R. D. Oldham, F.R.S., in the absence of the author :— “The Early History of the Indus, Brahmaputra, and Ganges.” By Lieut. Edwin Hall Pascoe, I.A.R.O., M.A., D.Sc., F,G.S., Superintendent Geological Survey of India. The occurrences of marine Nummulitic rocks show that in Eocene times a gulf of the sea extended up the Indus valley and the hill country tothe west of it, and eastwards along the southern margin of the Himalayas at least as far as the neighbourhood of Naini Tal. In the Himalayan region the marine deposits are succeeded by a series of red clays with intercalated sandstones and occasionally marine beds, regarded by the author as having been deposited in a series of lagoons. The Upper Tertiary deposits consist of a great series of conglomerates, sandstones, and silts of freshwater origin, which are known to extend along the whole of the southern face of the Himalayas. From these geological indications the author concludes that the first. effect of the commencement of the Himalayan uplift was the establishment of a great westward-flowing river along the southern face of the range, for which he proposes the name of Indobrahm. The distribution of Tertiary rocks on the northern side of the range suggests that here also a westward-flowing river was formed, which discharged either round the end of the range into the same sea as the Indobrahm, or flowed westward into the region of Turkestan and the Caspian Sea. The subsequent history of the drainage system consists of the capture of the upper waters of this river by a tributary of the Indobrahm, a cutting-back along the valley to form the eastward flowing Tsangpo, now the upper waters of the Brahmaputra, and the capture of the lower reaches in part by the Sutlej and in part by the Attock tributary of the Indobrahm, to form the Himalayan portion of the Indus valley. Meanwhile, on the southern side of the range, some of the tributaries on the eastern side of the Lower Indobrahm had cut back from the Sind region and cut off the original bend near Attock, to form the present plains of the Punjab ; and farther east, a river cutting back along the present line of the Gangetic delta and lower course of the Ganges and Brahmaputra, had captured the upper waters of the Indobrahm to form the present Brahmaputra. The same system of capture had worked westwards, until the tributaries of the Indobrahm had been Reports & Proceedings—The Royal Society. 237 successfully diverted from a westerly to an easterly drainage up to and including the Jumna River. The author finds proof of the recent date of the separation between the drainage-system of the Indus and that of the Ganges in certain historical evidence, indicating that the Jumna was a tributary of the Indus within the human period ; in the occurrence of the same species of freshwater porpoise in the two river-systems and nowhere else outside of them; and in the identity of the freshwater Chelonia of the two river-systems, the species being either peculiar to these drainage-areas or represented outside of them by distinct varieties. 4, March 26, 1919.—Mr. G. W. Lamplugh, F.R.S., President, in the Chair. At 6 p.m. a special general meeting was held in order to consider the following resolution of Council: ‘‘That it is desirable to admit Women as Fellows of the Society.”’ The President said: It will be within the etoilledion of most of the Fellows that the question of the admission of women to candidature for the Fellowship of the Society has been raised on more than one occasion in the past. It was considered in 1889 and 1901, and again, more systematically in 1908-9, when a poll of the Fellows was taken and three special general meetings were held, with inconclusive results. It is generally recognized that the course of events since these dates has materially changed the situation. Women have been welcomed to our meetings as visitors, and we have had many examples of their qualifications for Fellowship in the excellent papers which they have from time to time contributed to the Society. The value of these papers has been appreciated by all geologists, and has been repeatedly acknowledged by the Council in its awards. Therefore, in the opinion of the Council, it is no longer reasonable to maintain a sex-bar against qualified candidates for the Fellowship of the Society, and I am empowered by the Council to submit the above-mentioned resolution for your consideration. A ballot was then taken, and the resolution was declared carried by 55 votes against 12. I1.—Tue Royat Socrery. March 27, 1919.—Sir. J. J. ee O.M., President, in the Chair. The following paper was read :— ‘“The Morphology and Evolution of the Ambulacrum in the Kchinoidea.” By H. L. Hawkins, M.Sc., F.G.S. (Communicated by Dr. Henry Woodward, F.R.S.) A summarized account of the ambulacra in non- -Holectypoid orders is given. Bothriocidaris shows the simplest type of structure, and the most efficient for coronal strength. As podia increased, ambulacral plates multiplied, and the areas became mechanically weak. The main podial function in Regular Echinoids being adhesive, coronal weakness demanded modification. In most Paleozoic types, general 238 Reports & Proceedings—Edinburgh Geological Society. flexibility neutralized local weakness; but with the adoption of rigidity the problem reappeared. Hence arose ‘‘ plate-complexity ”’. The formation of compound plates is discussed. ‘‘ Grouping” precedes, and is distinct from, combination. Plate-reduction is due to ‘‘growth-pressure’’; combination to tubercle-growth. Elaboration of combination culminates in the Echinometride, where the compounds regain ‘‘ Bothriocidaroid ”’ proportions. In irregular Echinoids no combination occurs; grouping is often developed. Secondary specialization in Spatangids produces “« Paleozoic ” structures. The Holectypoida show four ambulacral types: (1) Plesiechinid (triad-groups adorally, primaries adapically) ; (2) Pygasterid (primaries throughout) ; (3) Pyrinid (triad-groups throughout) ; (4) Discoidiid (triad-groups adorally, dyad-groups adapically). Plesiechinid is primitive, and resembles the early Acrosaleniid type. Pygasterid indicates simplification, being morphogenically transitional from Diademoid to Spatangid structure. Pyrinid is persistent, resembling the ‘‘Echinoid” structure of Diademoids. Discoidiid is exceedingly elaborate, showing extreme plate-reduction. The Cassiduloidea are divided into Nucleolitoida and Cassiduloida (restr.). The former order is related to the Pygasteride ; its simpler members have Plesiechinid ambulacra, and Holectypoid structures appear in later forms. The Cassiduloida evolved through the _Echinonéide. There are three main trends of evolution in Echinoid ambulacra : (1) Diademoid, attaining plate-combination; (ii) Clypeastroid, attaining plate-destruction ; and (111) Spatangoid, reversionary. III.—Epinsvuren Grotoeicat Socrery. February 19, 1919.—Professor Jehu, President, in the Chair. 1. ‘A Historical Sketch of the Iron Industry in Scotland.” By M. Macgregor, M.A., B.Sc., of H.M. Geological Survey. Mr. Macgregor sketched the rise and development of iron- working in Scotland, more particularly in regard to the raw materials used. The small primitive furnaces of early times known as Bloomeries were described, and an account was given of the iron-works in operation in the Loch Maree district during the first half of the seventeenth century. The later furnaces in the central and west Highlands during the eighteenth century were then noticed in some detail. In all these charcoal was used as fuel. The smelting of Scottish Carboniferous clayband ores by means of coke and coal came into vogue soon after 1750, the year in which the Carron Ironworks began their long career. Since that time there had been three main stages in the development of the modern iron industry. These were as follows: (1) Rise of the Clayband Industry, 1760-18380; (2) Rise of the Blackband Industry, 1830-60; (3) Rise of the open-hearth Steel Industry, and period of imported ores, 1850 onwards. 2. Exhibition of Specimens of Norwegian Nepheline Syenite (Laurdalite) Boulders from Flotta, Orkney. By Dr.J.S. Flett, F.R.S. ' Reports & Proceedings—Mineralogical Society, 239 IV.—Mrvneratoercat Socrery. Mar a 18.—Sir William P. Beale, Bart., K.C., President, in the Chair. L. J. Spencer: ‘‘ Curvature in jonny The curvature of crystals is evidently of many different kinds, and due to as many different causes. Numerous examples, figured in the literature and illustrated by specimens in the British Museum collection of minerals, are grouped under the headings: curved crystallites and feathery microlites, capillary habit, aggregations of crystals, interfacial oscillation, vicinal faces, bent crystals and _ plastic deformation, twisted crystals, cylindrical (?) and spherical (?) crystals (a supposition leading to a reductio ad absurdum). Lieut. A. B. Edge: ‘‘Siliceous Sinter from Lustleigh, Devon.” The district round Lustleigh, near Bovey Tracey, is mined on a small scale for a very fine quality of micaceous hematite, which occurs there in well-defined lodes traversing the granite. At the Plumley Mine (now disused), on the walls of one of these lodes, is found a peculiar banded material, somewhat resembling lithomarge or halloysite, which on analysis proved to be a siliceous sinter or ' opal, with an approximate percentage composition of silica 70, water 21, hematite 6, alumina, soda and potash 3, and a low specific gravity, 1°73. It is hard and compact, and shows a beautifully banded structure, the layers being tinted to varying degrees by limonite and finely divided flakes of micaceous hematite. The general appearance of the material and the presence of delicately overfolded ripples in the banding suggest that it was originally deposited on the walls of the lode in the form of a jelly, and solidified by loss of water. Such loss continues at a very slow rate when specimens are kept in a dry atmosphere, and after some years the surface becomes soft and powdery. ‘he sinter is very fragile, breaking conchoidally even when most carefully handled; this may be caused by the shrinkage strains set up during solidification. The source of this hydrated silica is rather doubtful ; it probably formed part of the aqueous injection which deposited the hematite, but may possibly have been leached from the granite during the formation of the lode, A. F. Hallimond: ‘‘An Anorthie Metasilicate from Acid Steel Furnace Slags.”? A description of the slags will be communicated to the Iron and Steel Institute. The substance is a metasilicate of iron, manganese, calcium, and magnesium, and appears as flat, elongated crystals with the following characters: Forms 6 (010), m(110), 2£(110), p(112), 2(101), n (310), constants a 99° 37’, Bowral, y 82 o.e. abe —baltoGnl 1 0:49% = perteck cleavages parallel to m nel M,mM = 95°92’; colour clear amber yellow, not pleochroic; optical characters, 2V = 653°, negative, 8 = 1-701, axial plane nearly normal to the cleavage zone, extinction on @ 5°, acute bisectrix nearly normal to a. Dr. C. T. Prior: ‘‘On the Meteorites Adare and Ensisheim.”’ The percentage amount of nickeliferous iron and the ratio of iron to nickel in it were found to be respectively 18 and 18 in the case of Adare, and 33 and 33 in the case of Ensisheim, which results support 240 Correspondence—J. Reid Moir. the view that in chondritic meteorites the less the amount of nickeliferous iron the richer it is in nickel. Dr. G. F. Herbert Smith: ‘A Student’s Goniometer.’”? This instrument, which was made by Messrs. J. H. Steward, Ltd., is of the type in which the direction of reference is given by the reflection of some distant object in a mirror, and in which the axis of the graduated circle is horizontal. A ball and socket joint provides the mirror with all the necessary adjustments in direction, and it is also movable vertically in the plane of the axis of the eircle. ‘he crystal holder is provided with a simple and convenient form of adjustment which enables a crystal to be measured, as regards one-half, without removal from the wax. A pointer on a swinging arm facilitates the setting of the crystal in the axis of the circle. CORRESPONDENCE. MOUSTERIAN FLAKE-IMPLEMENTS. Str,—Mr. Henry Dewey, in his note “On some Paleolithic Flake-implements from the High Level Terraces of the Thames Valley”’ (Guor. Mac., February, 1919, pp. 49-57), in dealing with the fact that flint-implements of what is known as the ‘“‘cave”’ period, are generally made from flakes, states, on p. 55, that ‘“some are carefully worked on a disc-face, a facetted platform prepared, and by a single blow on this platform a complete imple- ment detached from the core. By this means half the work expended on their manufacture was saved . . . ’? The comparison here is with the earlier Paleolithic ‘‘ cave” implements exhibiting flake-scars on both faces. But the view, which for some unaceount- able reason seems widely held, that the flake-implement of Mousterian man was a labour-saving device is erroneous. The process of making a flake-implement was as follows: a large nodule or block of flint was first carefully shaped by flaking into a tortoise-like form, and this process almost certainly took as long as the manufacture of a normal Chellean or Acheulean cave -implement. But when Mousterian man had made what may be regarded as his core- implement, he proceeded to detach a flake from it, and after trimming if round the edges, to use this flake as an implement. And in many cases the core, over which so much labour had been spent, was thrown away as useless. I fail to understand how it is possible to regard this method of implement-making as demonstrating that Mousterian man was able to produce his flake-implements with * half the labour expended by the earlier Paleolithic people on their pointed and ovate artefacts. In fact, I see no connexion between the Chellean and Acheulean core-implements and the flake-implements of the Mousterians. ‘The technique of the latter is totally different, and was probably practised by a different race of people from the Acheuleans. J. Rei Morr. ONE HOUSE, FPSWICH. March 27, 1919. TABLE of BRITISH STRATA Compilers : Henry Woopwarp, LL.D., F.R.S., F.G.S. Horace B. Woopwarpb, F.R.S., F.G.S. ANY years have elapsed since the publication of a Table of British Strata. The Table of British Sedimentary and Fossiliferous Strata by Messrs. H. W. Bristow and R. ETHERIDGE and that by Mr. Bristow, showing the Relative Thickness of the Strata, date back to 1873. Meanwhile many changes have been made in nomenclature, and many new local subdivisions have been marked out in the series of Strata. To represent these in tabular form as an aid to the memory is one object of the present publication. The student should bear in mind that Nature does not draw the hard and fast lines which appear in the Table, and that the divisions, like those in human history, are epochs artificially limited for the convenience of grouping events. In many cases |. it is possible to indicate only the general position of the minor divisions in the great series of geological formations. Minute correlation of strata, dependent on organic remains, cannot here be attempted. The aim of the compilers has been to represent as fully and fairly as possible the views most widely accepted at the present time, and thus in grouping the Wealden in the Jurassic system and in retaining the Permian in the Paleozoic era they seek to assert general rather than individual opinion. Price 5s. net; Folded in book form, 6s. net ; Mounted on linen, with rollers and varnished, 16s. net. LONDON : DULAU & CO., LTD., 34-36 MARGARET STREET, CAVENDISH SQUARE, W. 1. GEOLOGISTS. SEVERAL Senior aa Junior Geologists, preferably with Oil experience, required for Geological Surveys .in . various parts of the World by an important British Company. Liberal terms, according to qualifications. —Address, Z. X. 222, care Deacons Advertising Offices, Leadenhall - eirect,. London, FC: 3. SCIENTIFIC BOOKS and SERIALS. 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No. 660. Decade VI.—Vol. VI.—No. VI. Price 2s. The \ eological Magazine Monthly Journal of Geology. k WITH WHICH IS INCORPORATED soa "st; > gS & THE ~GEOEOGIS % EDITED BY HENRY WOODWARD, LL.D., FY AND R. Ee RAS TAG, MAS EGS: \ ASSISTED BY Baga PrRoF. J. W. GREGORY, D.S8c., F.R.8. | Pror. W. W. WATTS, Sc.D., F.R.S. PROF. J. E. MARR, Sc.D., F.R.S. HENRY WOODS, M.A., F.R.S., F.G.S. sir JETHRO J. H. TEALL, Sc.D., F.R.S. Dr. A. SMITH WOODWARD, F.RB.S. JUNE, 1919. CONTENTS :— Page REVIEWS (continued). Page LMOLTOR TAI) NORES. eos cscenesceee ces. 241 | Fossils from Queensland ............ 277 ‘a Revision of Phacopids ............... 278 ORIGINAL ARTICLES. Phylogeny of Acorn Barnacles...... 278 Foliation and Metamorphism. By A Century of Science in America... 279 Professor T. G. BONNEY. (Con- Ore-deposits in Montana ............ 280 CHUL CH ys Gircekie. cod te cust ia vs oY Sed 246 | Inclusions in Antartic Lavas ...... 281 Non-German Sources of Potash. Geology of Kongsberg, Norway ... 281 yy Dia OMNES 350: ccs nod 251 | Glacier Lakes in Southern Norway 282 Noteson Yunnan Cystidea. Part III Ibimoston: ial bovuu oa liste s.eqn) ee eee 282 (continued). By Dr. F. A. The Charters Towers Goldfield...... 283 BATHER. «(Plate VE.)'e...5.:...4.. 255 | The Geology of Gatooma ............ 283 Drake’s Island, Plymouth. By - Enrichment of Copper Ores in IS AUD WVicsimas ccs ecse aaaenie 262 SPAIN Wh sth teacsaaten age toa eRe ree 284 The Minerals of the Lower Green- Hing Ore trom) Japan. ).ss.s.24-.5.0 284 sand. By R.H. RASTALL. (Con- Pre-History in Hssex.................. 284 ELLE CIED RD AER OSE SR PS 265 | Another Fossil Tzetze Fly ......... 285 A Scandinavian Erratic from the Orkneys. By W. I. Saxton REPORTS AND PROCEEDINGS. ange 2. EOPWOOD . .\.2ser..c05.: 273 | Geological Society of London ...... 285 Rass. Paleontological Society.. Harada Gee 288 The Coral-reef Problem............... 274. I=. -5 OBITUARY. Subsidence of Coral Reefs............ Au Oren lieben O «1 Gye, Baul Clvaeatie ce senoe cates cas 288 The Antiquity of Parasitic Disease 276 | Fernand Priem -........................ 288 LONDON: DULAU & CO., Lrp., 84-86 Marcarrr STREET, CAVENDISH SqQuaRE, W.1. JAMES SWIFT & SON, Manufacturers of Optical and Scientific Instruments, Contractors to all Scientific Departments of H.M. Home and Colonial and many Foreign Governments. GrandsPrix, Diplomas of Honour, and Gold Meda/s at London, Paris, Brussels, etc. MICROSCOPES see FOR GEOLOGY, MINERALOGY, PETROLOGY. Sole Makers of the “DICK” MINERALOGIGAL MICROSCOPES. Dr. A, HUTCHINSON’S UNIVERSAL CONIOMETER. UNIVERSITY OPTICAL WORKS, 81 TOTTENHAM COURT ROAD, LONDON, W. t. een s Microscopes for Geo _ WATSON & SONS manufacture a special series of Microscopes for Geo- logical work. All have unique features, and every detail of construction has been carefully considered with a view to meeting every requirement of the geologist. All Apparatus for Ceology supplied. 2 asa WATSON’S Microscopes are guaranteed for 5 years, but last a lifetime, and they are all BRITISH MADE at BARNET, HERTS. . WATSON & SONS, Ltd. (ESTABLISHED 1837) 313 HIGH HOLBORN, LONDON, W.C.1. Works:—HIGH BARNET, HERTS. THE GEOLOGICAL MAGAZINE / NEW SERIES. DECADE VI. VOL. VI. No. VI.—JUNE, 1919. NOTICE OF CHANGE OF ADDRESS. On and after June 1 all communications for the Editor of the “Geological Magazine” should be addressed to R. H. Rastall, Esq., M.A., F.G.S., Christ’s College, Cambridge. Letters for Dr. Henry Woodward, F.R.S., to be sent to Tudor Cottage, Clay Hill, Bushey, Herts. Books and parcels to be directed to Messrs. Dulau & Co., 34-36 Margaret Street, Cavendish Square, W.1. HMDITORIAL NOTES. Y the death of Sir Frank Crisp, Bart., on April 29, in his 77th year, science in general has lost a very generous supporter anda valuable fellow-worker. Late senior partner in the well-known City firm of Ashurst, Morris, Crisp & Co., solicitors, Throgmorton Avenue, he devoted fifty years to law, but gave all his leisure and much of his income to scientific pursuits. He was a keen student and lover of microscopic research, and was an ardent supporter and honorary secretary of the Royal Microscopical Society, for which Society he obtained a Royal Charter. From 1879 to 1889 Crisp wrote the bulk of the invaluable bibliographical abstracts in the Journal R.M.S., and generously supported the publication by every means in his power. He formed, with much knowledge and at great expense, a most instructive and remarkable collection of instruments from the very earliest known microscopes to those of the most modern and costly construction provided with a great series of lenses of every kind. hese he presented to the nation for the new Science Museum at South Kensington, the delay in the completion of which (caused by the War) has hitherto prevented their exhibition to the public. Sir Frank was also a Fellow of the Linnean Society, on the Council of which he served for nearly forty years, filling the various offices of Treasurer, Vice-President, and Solicitor. He procured the modification of the Society’s charter to cover the admission of women as Fellows in 1904. He was pre-eminent as a botanist and collector of rare and remarkable living plants, to procure which he spared no expense. In Alpine plants alone he has brought together upwards of four thousand different species. His rock-garden at Friar Park, Henley, crowned with an DECADE VI.—VOL. VI.—NO. VI. 16 242 Editorial Notes. accurate model of the Matterhorn, needed for its construction no less than 20,000 tons of Carboniferous Limestone from Yorkshire, and with the other gardens, caves, lakes, and cascades renders this beautiful spot one of the finest gardens in England. At the time of his death he was preparing a great work on Gardens, Ancient and Modern, for which he had gathered an ample library of rare and curious books. # co % 2 * Now that Belgian scientific publications are beginning to reappear, we are not surprised to see, accompanying those of the Académie Royale, a ‘‘ Rapport succinct sur l’Etat du Palais des Académies. apres le Départ des Allemands”. This has been compiled by M. Louis le Nain, Secrétaire de la Commission Administrative, whose duty it was to report on the work necessary for restoring the apartments to a condition fit for their original purposes. From this report it is clear that the work of restoration will take some considerable time, as the building and its contents had suffered during the German occupation. Certain rooms had been used as. hospital wards, one even being set aside for tubercular cases, others. as store-rooms, and so on, thus necessitating some structural alteration. Kverywhere M. le Nain found the utmost confusion, disorder, and filth; and the photographs accompanying his report show this to be the case. The Library too had suffered ; some books had disappeared, others were misplaced, but when found were in a damaged condition. This was particularly the case with the Stassart Collection. Certain Belgian busts and paintings had been disfigured, the portrait of Leopold I being decorated with an iron cross; others had been damaged. M. le Nain therefore considers that the building must be thoroughly cleansed and repaired before it can be again used, and that the number of objects stolen, lost, or misplaced must be discovered. Some time must elapse before this can be accomplished. * % co % % Aw oil-painting of Gideon Algernon Mantell has recently been presented to the Geological Society of London, by subscription among a number of the Fellows. Unfortunately, the history of this painting is not known. The collection of oil-paintings in the possession of the Society is very small, consisting of only nine, including the portrait of Mantell, and that of Dr. Henry Woodward, referred to in these notes in the April number. ‘The other oil- paintings, at present hung in the Society’s Meeting Room, consist of the portraits of William Smith, Buckland, Lyell, De la Beche, Phillips, Huxley, and Prestwich. There is also the painting of the group of geologists at the meeting of the British Association at Newcastle in 1838. On the walls of the Council Room are hung the portraits of the former Presidents of the Society. This series is complete, and consists chiefly of engravings, with large photo- graphs of the later Presidents. Editorial Notes. 243 Tue veteran Swiss geologist, Albert Heim, attained his 70th birthday on April 12,1919. The event has been duly commemorated by the publication of a Festschrift, issued by a special committee, with Dr. Paul Arbenz as chairman, as a double number of the Vierteljahrschrift der Naturforschenden Gesellschaft in Zurich. This is a handsomely prepared volume of 518 pages and 12 plates, and contains 24 separate contributions, besides a complete catalogue of Professor Heim’s publications. Most of the contributions to this Festschrift naturally deal with various branches of the geology of Switzerland; other subjects, however, have received attention. Thus, A. Hartmann deals with the hydrology of the Magdalena Bay district, in Lower California; L. Zehnder contributes a short discussion on the causes of geological epochs; HK. Blumer reviews the principal petroleum deposits; E. Bloesch gives an account of the tectonics of the Front Range in Colorado; while W. Staub presents the results of recent geological exploration in Eastern Mexico. ‘he value of Albert Heim’s own work is well recognized in this country; he was elected a Foreign Correspondent of the Geological Society of London in 1887, and was made a Foreign Member in 1896. It will be remembered that he was one of the six distinguished geologists on whom the University of Oxford conferred the honorary degree of D.Sc. on the occasion of the Society’s Centenary in 1997. Tse views set forth in the Report of Sir Joseph Thomson’s Committee on Scientific Education (Report of the Committee of the Privy Couneil for Scientific and Industrial Research for the Year 1917-18) are evidently endorsed by opinion in the Colonies. In the recently established New Zealand Journal of Science and Technology (the organ of the New Zealand Board of Science and Art), the matter is discussed by the editor under the title of ‘‘ Training Research Workers’’. Certain passages are quoted from the Privy Council Report, and particular stress is laid on the prefatory exhortation to prompt action. In the opinion of the editors of this New Zealand Journal; even if scientific research were adequately endowed in the Dominion a dearth of investigators would be at once apparent. Granted that the true research spirit is a matter of natural ability rather than the result of training, it still remains that the potential worker must be able to get proper facilities for development. The War has made us aware of many deficiencies: one of these is the need of adequate scientific training of a University type. ‘The feeling of the natural independence of the New Zealand youth is not confined to that Dominion; he wants to find himself as independent financially while pursuing his University course as he would if starting a business career. An extension of the scholarship system is the only means of attaining this except in the case of the rich. Grotocy and geography have so much in common that it is not always easy to draw the line between them. It is accordingly 244 Tditorial Notes. a matter of some interest to the geologist that the University of Cambridge has recently established a Tripos in Geography. Hitherto geography has not been recognized by any British University as a subject for a degree in honours, and the highest distinction awarded was a Diploma, such as that of Cambridge or Oxford. The Diploma in Geography has proved a very valuable and useful quali- fication to teachers, but it did not carry with it an honours degree. The new Tripos is divided into two parts. Part I corresponds very closely with the old examination for the Diploma, and will probably still remain the most useful qualification for teaching purposes. It covers a wide ground, and no candidate can pass it creditably without showing a sound and broad knowledge of all the different branches of geography. Part II is designed more for the specialist, and the man who intends to undertake original research .takes up one or two sections only, but is required to study these more deeply and to be acquainted with the other branches of know- ledge which bear upon the section which he selects. ‘There is, for instance, a section ‘Geomorphology ”’, and the student who chooses this must be a geologist. ‘There is, however, a geographical side to geology, and it is to this, and its influence on surface features, rather than to details of stratigraphy, paleontology, and petrology, that he will devote most attention. The other subjects in Part II are Geodetic and Trigonometrical Surveying, Oceanography and Climatology, Historical and Political Geography, and Economic and Commercial Geography. * % % # % WE referred recently in our Editorial Notes to the question of the existence of workable quantities of petroleum in England; since that date another important contribution to the subject has come to hand in the shape of a paper read to the Manchester Geological and Mining Society by Mr. T. Sington on ‘‘ The Search for Petroleum in Derbyshire now in Progress’. This paper describes the exact situation of the seven boreholes now being put down to the south- east of Chesterfield and their relations to the geological structure of the district. The author points out in the clearest terms that if any considerable amounts of oil or gas now exist in the rocks to be penetrated by these bores they have had every opportunity to show themselves, owing to the abundance of colliery workings in the neighbourhood, and he feels confident that none will be found. In the discussion that followed this view received the support of every speaker, including the weighty authority of Professor Boyd Dawkins, who pointed out that while petroleum is often found in the Coal-measures, it is always in quantities to be measured by a tea-spoon rather than a bucket, and that it is extremely improbable that at lower levels it will occur in any larger proportion. This entirely agrees with the views of the authorities already quoted. In this connexion the Editors are pleased to be able to say that they have in hand a valuable paper by Mr. V. C. Illing, which will be published in an early issue of the Magazine, after the conclusion of the paper on Potash by Dr. Holmes begun in the present number. * # % * # Editorial Notes. 245 Anistne out of the previous question, as they say in Parliament, it is perhaps permissible once more to draw attention to a most important subject, namely, the proper examination, treatment, and preservation of the cores from borings. According to the details given by Mr. Sington, there will be no cores from the Derbyshire borings; nevertheless the principle is the same: all material obtained from deep bores should be inspected by competent geologists and the results carefully recorded. Cores are frequently treated in the most haphazard fashion, being examined only by the borer, who often records their character in jargon intelligible only in the district where they happen to be, and totally useless anywhere else. It is rarely that a core is inspected by a competent geologist and the results published in a scientific form. It is, of course, obvious that it may be necessary in certain cases that the details of a boring should be kept secret for a time, but in the national interest control should be compulsorily exercised over all borings, which should be inspected during their progress by Government geologists and the facts carefully registered as the work progresses. Thus intending prospectors could at any rate obtain information as to whether the work proposed had already been done in that particular district, and unnecessary expenditure thus prevented. One of the most important functions of applied geology is to prevent people wasting their money on fruitless enterprises. Tue Department of Mines of the Dominion of Canada has shown commendable promptitude in the issue of its ‘‘ Preliminary Report of the Mineral Production of Canada during the Calendar Year 1918”, which bears date February 27, 1919. One can only say O si sic omnes! The total value of the minerals produced during the year shows an increase of 10°8 per cent over that of 1917, while since 1913, the last complete year before the War, the increase is no less than 44:3 per cent. More than half of the increment of value since 1917 is due to the higher price of coal, while silver, cobalt, and asbestos reached considerably higher prices, the actual pro- duction of the two latter being also “higher. Copper, lead, and molybdenite show a considerably greater output, but the price of the last has fallen off sadly, vane to the lessened demand for munition purposes. For the first time for some years a small output of tungsten is recorded from the Yukon, Manitoba, Nova Scotia, and New Brunswick. The nickel industry of the Sudbury district fully maintained its position, and many of the minor products and non-metallic minerals showed substantial increases, especially petroleum, magnesite, and gypsum. Altogether the mineral industry of the Dominion appears to have been in a flourishing condition in 1918. ORIGINAL ARTICLES. —— I.—Fottation and MeEramoreHismM IN Rocks. By Professor T. G. BONNEY, Se.D., LL.D., F.R.S. (Concluded from p. 203.) N pressure-modified gneisses and schists certain minerals are often distinctly secondary in formation; actinolitic hornblende replaces ordinary hornblende in a gneiss, as on the southern side of the St. Gotthard Pass (81), or in a dark mica-schist, as in the Binnenthal (32), or a tremolite appears in marble near the Campolungo Pass (88). A mixture of crushed hornblende and felspar gives rise to a biotite, small flakes of which may be built, like bricks, into a newly-formed large crystal of hornblende, especially towards its exterior (34). Glaucophane in hornblendic rocks, such as diorites and eclogites, is often a secondary mineral (35), some constituents derived from a crushed soda-felspar having combined with those of the original hornblende. Rather large biotites have formed in a dark mica-schist in the Binnenthal, and here also some of them have been developed at right angles to the main pressure, but others in the direction of it (86). Scales of chloritoid, sometimesa third of an inch in diameter, are secondary formations in some gneisses and chloritic schists, and kvanites in some micaceous schists suggest a possible reconstruction of an original mineral. Chlorite itself is a mineral of secondary origin, and such rocks as smaragdite-euphotide (37), saussuritic gabbro, and possibly even ordinary gabbro! are all more or less altered from their original condition, and in some at least of these cases pressure may have been a factor in the change. Besides this, new felspars may be formed in rather basic igneous rocks which have been much crushed, such as the griiner Schiefer of the Alpine and other regions.” In most of these cases pressure has been essential as a preliminary factor (i.e. the rock must have been more or less crushed), but how far it has operated in the ‘‘rebuilding”’ process is less easily determined. Water has probably aided, and there may have been some, though not a great, elevation of temperature. We can also find instances of intermediate or partial metamorphism, i.e. rocks in which an original fragmental structure has not been wholly obliterated. Of this the noted section at Obermittweida affords a striking example (89). Here a mass of gneiss, very probably of igneous origin but subsequently affected by pressure, is overlain by conglomerates and other sedimentary rocks. The matrix of the one and the materials of the other are sufficiently metamorphosed to 1 Diallage may be always a mineral of secondary origin; at any rate, we can detect under the microscope grains of augite partly converted into it, and discover that the hornblende in not afew diorites was once an augite; but on the history of hornblendic gabbros it is needless to dwell (88). 2 These, as it has been proved, are plagioclase, but with a higher percentage of silica and soda than the original mineral : albite or oligoclase, with a slightly porphyritic habit, forming in a rock of which labradorite was a constituent. These, it may be added, often fail to exhibit the characteristic oscillatory twinning. J itay I aE Bonney—Foliation and Metamorphism, 247 convert what was once ordinary detritus into fine-grained mica (mostly biotite) and quartz, probably authigenous, but as that matrix becomes coarser, so the traces of a clastic origin grow more distinct, till that becomes conspicuous in the breccias or con- glomerates. I recognize in their fragments under the microscope the followins—granitoid rock (3 varieties), mica-schist (1), quartz-schist (4), quartzite (2), ?halleflinta (2); still, even in these, mineral changes appear to have occurred, some of which at least may be later in date than the formation of the fragment. The cuttings on the Genedien Pacific Railway on both sides of Sudbury Station exhibit similar cases of incomplete metamorphism.’ Here we find two groups of rocks, one of which is more highly meta- morphosed than the other, and is in much the same condition as that at Obermittweida. ‘The matrix is an aggregate of biotite and quartz with some felspar. The first is mainly, the second to some extent, at least, authigenous, the third probably clastic, though it may have undergone subsequent augmentation. The larger fragments also exhibit some changes, secondary quartz and white mica being produced locally in the felspar, and the larger grains of quartz are replaced by a mosaic of this mineral. Biotite occurs more sparingly, in little flakelets, both clustered and isolated, which also suggests a breaking up of original constituents of that mineral. Another group, probably rather higher in position, occurs to the west of Sudbury, which contains fragments of volcanic rocks and shows less signs of metamorphism. There is also a group, traversed, as I was informed, by the railway from Sudbury Station to Algoma Mills and Saulte St. Marie, which seems to have been as much metamorphosed as the Upper schists of the Alps.” The important fact, however, in the’two groups mentioned above is that, while retaining indubitable traces of clastic origin, they indicate very considerable mineral changes, which, however, differ from those directly resulting from either water, or pressure, or heat, when operating separately, though probably demanding a rather considerable and prolonged action of the last agent. We pass now to rocks, the origin of which is indubitable and the metamorphism only micro- mineralogical. One instance will suffice, because this exhibits the most marked departure from its original condition, the group of the phyllites, a name often employed (as is almost inevitable) rather vaguely, but which may be conveniently restricted to argillaceous cleaved rocks, in which a minute secondary mica has been developed in such large quantities as to constitute the greatest part. These flakelets mostly lie in the same direction, i.e. perpendicular to the direction of maximum pressure ; in fact, a phyllite is the first marked step in the passage from a slate to a schist. Phyllites occur in greatly folded districts, such as parts of the Alps, Brittany, Scandinavia, Scotland, and Wales; indeed, are frequent in mountain regions, past or present. 1 Locally these are broken into by moderately coarse syenites, sometimes almost hornblende granites, and by basie rocks. 2 A few specimens were shown to me at Sudbury. 248 Prof. T. G. Bonney—Foliation and Metamorphism. One or two silicates, larger in size than the other constituents, are sometimes formed in this stage of metamorphism, but as they may become very impure by including material from the ground-mass, precise identification is often difficult, but they probably represent dipyr, couseranite, and a colourless ehloriteidl In rare instances small idiomorphic garnets are found in rocks, the matrix of which shows little signs of change. These have a peculiar structure which distinguishes ‘them from the ordinary garnet of true schists and igneous rocks, and are sometimes associated with ‘‘ bunches” of small actinolitic hornblende, almost colourless. The evidence as to the origin of these minerals is not decisive, though it suggests the action of heated vapours (42). The knoten and prismen, associated with crinoid and other organic relics of Liassic age, in the mountains above the Lukmanier Pass, on the eastern slope of the Nufenen Pass, and on or near the Nufenen Stock, are remarkable instances (41). I have passed over ‘one mineral, tourmaline, which is generally, if not always, a result of metamorphic action, because its mode of occurrence links it more closely with contact metamorphism. It is apparently the result of pneumatolytic action on the aluminous minerals in a rock, the felspars and the biotites in those of igneous origin (usually the granites) and the clayey constituents of the sedimentary. It also occurs in veins traversing these rocks, and especially granite masses, in association with quartz, fluor-spar, lithia-micas, chlorites, cassiterite, and one or two other minerals of less frequency, and the main difference from the ordinary results of contact metamorphism, which I have not discussed because they form so distinct a category, is that, as the tourmaline appears in the intrusive rock, which has produced that metamorphism, this mineral must be later in date than it.’ Of this mode of occurrence the rock called luxulyanite is the most striking example (48). The conversion of the felspar in a massof granite into the material called china clay, so strikingly illustrated in the Devon—Cornwall region, and often closely associated with the tourmalinizing agencies, is strictly speaking a metamorphic process, and a still more striking change is occasionally found in the replacement of the quartz in a eranite by fluor-spar (44). Other igneous rocks have undergone conspicuous metamorphism since they first solidified. Of these the replacement of augite by hornblende, and felspar by saussuritic minerals, has already been mentioned, but some diabases exhibit still greater changes. These, however, so far as I have seen, occur only in small masses, and generally in regions where pressure appears to have co-operated with water. The result has been the removal of much S10, and MgO, and the formation of a peculiar chlorite with a much higher percentage of alumina than in those ordinarily described (45). But serpentine is the most conspicuous instance of an igneous 1 Tt may also appear in the associated sedimentary rock, which shows the ordinary effects of contact metamorphism, but suggests by its mode of occurrence that it is due to some subsequent action. Prof. T. G. Bonney—Foliation and Metamorphism, 249 rock subsequently metamorphosed. Originally a peridotite,’ and frequently occurring in large masses, as at the Lizard and in the Alps, it has been converted by gradual change into a mass of flaky serpentine, as was described in my first paper on the Lizard, to which I have already referred,* and this rock also, by further action of water, may be altered with a talc-schist (46). An exceptional kind of chlorite-schist which occurs, apparently intrusive, in talcose-serpentine on the Gorner Grat and in Anglesey, has once been, as already mentioned, a diabase, and dykes of the latter can be seen at the Lizard occasionally to pass into varieties of ‘‘potstone”’, while the so-called white-trap is another modifica- tion of a basaltic rock too well known to need more than mention. The metamorphic rocks still present difficulties—points in their history which require further elucidation—but during the last half-century, as I know from my own experience, and as any one can ascertain by consulting the books and papers, which at the beginning of that period were regarded as authorities, the mists which then obscured knowledge have been largely dispersed, and many misleading and erroneous notions have been banished. The passage of sedimentary into igneous rocks, once so confidently asserted, has proved to be no better than a figment of the imagina- tion. It is possible, of course, that a sedimentary rock may be melted down, especially if small fragments of it are caught up in large masses of molten material, but even these appear, as a rule, to be so refractory that little evidence can be found in its favour.* The gneiss and schists, the rocks commonly called metamorphic, prove, as arule, to be more ancient than any strata to which a date can be assigned, and belong, apparently, to an era in the earth’s history anterior to the appearance of life, when the temperature of its crust. rose more rapidly in a downward direction than at the present day. This statement, fifty years ago, would have been scouted as heretical by most geologists; I think, however, that the bulk of those who have studied petrology, not only in the field, but also with the micro- scope, would now consider it to be the more probable hypothesis. BIBLIOGRAPHICAL REFERENCES. I haye omitted my own name where, as in the majority of cases, the papers are written by myself. Q.J. denotes Quarterly Journal of the Geological Society, G.M. Geological Magazine, M.M. Mineralogical Magazine. 1. Q.J. xlvii, p. 476; lii, pp. 22, 27-30; ‘‘ Crystalline Schists of the Lizard,’’ pp. 21-33. 2. Q.J. xxxili, p. 888; xxxix, pp. 11, 16. 1 T believe it is generally a deep-seated rock which occurs more often in bosses than in dykes, and never, so far as I have been able to ascertain, as a flow. 2 Perhaps the minutely flaky form of serpentine named antigorite may be due to subsequent pressure during or subsequent to the action of water (47). * The dark patches in igneous rocks have been discussed in an excellent paper by Mr. J. A. Phillips (Q.J. xxxvi, pp. 1-22), but I regard them, more often than he has done, as remnants of fragments of much older rocks, or pieces of a more basic igneous rock that have been broken off and carried along by the moving magma. 250 Prof. T. G. Bonney—Foliation and Metamorphism. ‘(With E. Hinz) Q.J. xlviii, p. 122. Q.J. xlvii, pp. 475, 480 (with General MAcMAHoN); xlviii, p. 135 (with H. Hi); Ixviii, p. 32. G.M. 1894, pp. 118, 119. (With E. Hinz) Q.J. Ixviii, pp, 41-3. Q.J. xlii, Proc., p. 68. G.M. 1894, pp. 115, 116. Proce. Geol. Assoc. xy, p. 6. Q.J. xlii, Proc. pp. 70, 71. G.M. 1894, p. 116. C. Lapworth, ‘‘ Secret of the Highlands’’: G.M. 1883, pp. 120, 193, 337. Geological Structure of North-West Highlands (Mem. Geol. Sury.), pp. 472-3. 14. J. Lehmann, Hntstehung der Altkr ystallinischen Schiefergesteine, ete., 1884 ; more especially claire Xvi-viii. 15. Q.J. xlix, pp. 94-103, 105-112 ; 1, pp. 279-284. 16. Q.J. xlv, pp. 93-7; ik pp- 358-67. 17. J.B. Jukes, Students’ Manual of Geology, 1872, (ed. A. Geikie), p. 144. 18. J. B. Jukes, wt swpra, pp. 246, 366. Also A. H. Green, Geology, 1876, pp. 271, 292-5. By 1878 I had convinced myself from personal examination that the important cases mentioned at the latter reference were quite wrong. 19. Crystalline Rocks of the Lizard, 1914, pp. 9, 21-33. 20. Q.J. xlvi, pp. 199-204, 208-13, 217-21; 1, 297-90. 21. Q.J. xlv, pp. 91, 92. 22. G.M. 1893, p. 204. ' 23. G.M. 1895, p. 400. 24. Q.J. xlvi, pp. 200-2. 25. Q.J. xlvi, p. 217. 26. Q.J. xlix, p. 89. 27. G.M. 1901, p. 166. .J. 1894, pp. 297-300. pad ed feed ed HOC COU hens Q.J Q.J. 1899, pp. 91, 92. Q.J. xl, pp. 3-5. 31. Q.J. liv, pp. 361-3. Q.J. xlix, pp. 108-9. Q.J. i, p. 299. Q.J. liv, pp. 366-7. 35. M.M. vii, pp. 1, 151, 191; Q.J. xliii, p. 303. 36. Q.J. xlix, p. 106. 37. Phil. Mag. 1892, pp. 237-48. 38. Q.J. lxviii, p. 51. 39. Q.J. xliv, p. 25. Seealso T. M’K. HUGHES, id., p. 20. 40. Q.J. xliv, pp. 33-9. 41. Q.J. xlii, Proc., 73-5; xlvi, 214-21, 299-301. 42. G.M. 1901, pp. 163-6. C. A. RalIsIn, Q.J. lvii, pp. 63-71. 43. M.M. i, pp. 215-21. 44. Trans. Geol. Soc. Cornwall, x, pp. 180-6. See also M.M. vi, p. 48. 45. G.M: 1890, pp. 538-41. 46. G.M. 1890, pp. 532-42; 1897,pp. 110-13. 47. (With C. A. RatstIn) Q.J. lxi, pp. 699-714. Dr. A. Holmes—Non-German Sources of Potash. 251 Il.—Non-German Sources or Porasu. By ARTHUR HOLMES, D.Sc., A.R.C.S., F.G.S. Introduction—Natural History of Potash—Saline Deposits—Alsatian Deposits —Spanish Deposits—Abyssinian Deposits—Natural Brines—Searles Lake— Nebraska and Utah—Tunis—Saltpetre—Kelp—Other Organic Sources— Insoluble Potash Minerals—Felspars—Leucite—Glauconite—Alunite—Dust from Cement Kilns—Blast Furnace Flue-dust. T is scarcely necessary in this Magazine to insist upon the vital importance of potash, or upon the reasons which led to the former economic dependence of our own and many other countries on German resources. The shortage of potash, which arose as a direct consequence of the outbreak of war, became more and more accentuated until the latter part of 1917, when production from -various revived and newly discovered sources began appreciably to relieve the then seriously acute position. In 1913, the last complete year of the older conditions, over £900,000 worth of potassium salts were imported from Germany by Great Britain, against imports of only half that value—much of which was cream-of-tartar, a by- product of the wine industry—from all other countries. It is now safe to say that the German monopoly is completely broken, partly because of the return of Alsace to France, and partly because of the discovery of new deposits, and the successful development, under the stimulus of war conditions, of new methods of potash recovery from sources formerly unremunerative or unsuspected. The purpose of this article is to pass briefly in review the chief sources from which potash is, or may be, profitably extracted, other than those of the famous German deposits, which already have a voluminous and familiar, or at least readily accessible, literature. The natural history of potash is very different from that of soda. In average igneous rock the percentages of these two constituents are practically equal, while in average sedimentary (exogenetic) rocks potash is two and a half times as abundant as soda. Comple- mentary to this selective retention, the potash of river waters amounts to no more than a quarter-of the soda, and in sea water the proportion is still further reduced to a thirtieth. The following figures, based on denudational statistics, bring out clearly the difference of behaviour between the two elements. POTASSIUM. SODIUM. (Figures represent millions of millions of tons.) In ocean water : 5 : s 3 450 12,600 In sedimentary rocks . : : . 18,300 7,400 18,750 20,000 In parent igneous rocks from which the sediments were derived é : - 19,700 20,000 Unaccounted for . : : : 950 = In round figures the circulation of sodium is completely accounted for, whereas a large balance of potassium, twice the quantity dissolved in the oceans, remains over. This amount, or something 252 Dr, A. Holmes—Non-German Sources of Potash. of the same order, must be mainly present in organisms. It is well known that potassium salts are preferentially adsorbed by colloidal and physically analogous substances from solutions that percolate through soils, and from the latter they are taken by plants, and thence by animals. Of the potash that reaches the sea a high proportion is similarly abstracted by seaweeds, while another considerable fraction is adsorbed by ferruginous and siliceous matter to form glauconite. Without going into further detail, the circula- tion of potash from its original magmatic sources is summarily set forth in the following scheme, with a view to indicating the deposits from which extraction is economically practicable, or likely to become so if need arose :-— MAGMAS Rocks rich in Alunite Ver IGNEOUS MAGMATIC pce Leucite, Orthoclase, ; 2) D t Microcline, or sas} poeKe fea {0) Bee Shree SURFA aan ROCKS ST tae il KORGANIC ai ene en os Seaweed (Kelp) Deposits Vegetation, Saline Deposits \ and Animal Brines Refuse Z (Nitrates): Clay Marl Limestone Transtone Coal Dust from Cement Kilns Flue Dust from Blast Furnaces ‘ SaLinE Depostrs. In addition to the extensive German salt-fields,! generally referred to as the Stassfurt deposits, there are at least half a dozen areas where beds of potassium salts are associated in workable quantities with saline formations. Three of these, in Alsace, Spain, and Abyssinia, are of outstanding importance. In Galicia, Lower Miocene beds of kainite and sylvite are mined at Kalusz, but as the output is insufficient to supply the local demand, these deposits are, for us, of minor interest.2 Numerous potash-bearing seams have been discovered in the mines of the Salt Range of India.* Their commercial development, however, has been restricted by the irregularity of the potash and the abundance of sulphates, and at present their exploitation has scarcely passed the prospecting stage. In Chile there are extensive salt deposits lying to the east of the nitrate fields, and one of these, the Pintados Salar, which is skirted 1 J. W. Gregory, Trans. Geol. Soc. Glasgow, vol. xvi, p. 12, 1916. 2 Zeit. fiir das Landwirtschaftliche Versuchswesen, vol. xviii, p. 892, 1914. > W. A. K. Christie, Rec. Geol. Surv. India, vol. xliv, p. 2438, 1914. Dr. A. Holmes—Non-German Sowrces of Potash. 2538 by the railway from Iquique, has been found by chemical prospecting to be potash-bearing over an area of 20 square miles.’ The potash is confined to a hard superficial crust averaging a foot in thickness, which overlies a loose granular deposit of glauberite and gypsum. The composition of the crustal salts is approximately 70 per cent NaCl with 80 per cent of sulphates, among which glaserite, (K, Na), SO,, is the chief. Asin the Indian deposits, the effective extraction of potash presents a difficult problem to chemical engineering. Deposits that hitherto have not been worked, and of which very little is known, are said to occur in Holland, Sicily, Russia, Morocco, and Peru. Alsatian Deposits.—The Alsatian deposits were discovered near Mulhouse in 1904 during a survey of the district for coal and oil by borings. ‘hey have since been thoroughly investigated, and are known to underlie an irregular oval-shaped area of about 80 square miles,? bounded by the Jura on the south, the Vosges on the west, and the Rhine on the east. A continuation of the same formations has also been recognized across the Rhine, but as yet the occurrence of potash in Baden remains hypothetical. The general succession of the Alsace deposits is stated in the accompanying tablein comparison with those of other areas. Potassium salts occur in two well- marked beds separated by 50 to 80 feet of dolomitic marl. The lower bed is both thicker and more extensive than the upper, and is encountered at depths varying from 2,000 to 3,300 feet in different parts of the field. ‘The beds are continuous, and as they are only very gently folded, unlike the Spanish deposits described below, they can be worked without difficulty. Moreover, they are superior in character to the German deposits because of the absence of carnallite. Each bed consists of practically pure sylvinite, in bands alternately red and grey, the average percentages of KCl being 85 and 380 for the upper and lower beds respectively. The field, as a whole, is estimated to contain over 400 million tons of KCl, a reserve ample, were if necessary, to supply the combined requirements of France, Great Britain, and the United States for several centuries. The Alsace deposits differ most conspicuously from those of other regions by the deficiency of sulphates, salts containing MgSO, being absent, while even anhydrite and gypsum are less abundant than is usual. On the other hand, the succession of deposits begins with dolomite, and dolomitic beds occur at various horizons throughout, indicating that calcium and magnesium were present in normal quantities, and that they were precipitated as carbonates rather than as sulphates. The absence of sulphate is not improbably due to the bituminous character of the deposits, and conforming to the implied suggestion of reduction the bituminous beds are found to be unusually rich in sulphides. 1H. 8. Gale, Eng. & Min. Journ., vol.cv, p. 674, 1918; R. C. Wells, ibid., p. 678. 2 For a map of the area and a general discussion of its commercial value and political significance, see Paul Kestner, Journ. Soc. Chem. Ind., vol. xxxyvii, p. T 291, 1918. , 254 Dr. A. Holmes—Non-German Sources of Potash. Wittelsbach District, Suria and Cardona Southern Harz District, Alsace. District, Spain. Germany. Oligocene marls . . Oligocenemarls,sand- Triassic Sands, sandstones, stones,andlimestones. Upper Permian \ clays, and shales. Marls with rock-salt, anhydrite, and gypsum. Rock-salt and clay. . Upper rock-salt . . Younger rock-salt. y Anhydrite . . . . Anhydrite. Dolomitic salt-marl . Salt-clay. . . . . Salt-clay. Zones of potash salts in dolomitic marl . . Zones of potash salts. Zones of potash salts. Rock-salt with bitu- Lower rock-salt with Older rock-salt with minous clays. . . partingsofanhydrite. partings of anhydrite (year rings). Anhydrite . . . . Anhydriteand gypsum. Anhydrite and gypsum. Dolomite. Green-grey marls . . Hocenelimestone . . JLower Permian limestone. Spanish Deposits.—Just before the war a zone of potash salts was discovered in Catalonia, near Cardona, a locality already well known for its rock-salt mines. The general succession has been revealed by a large number of bore holes and by a series of shafts which mark the beginning of the productive exploitation of the deposits. As shown in the detailed sequence set forth above, there is a marked likeness to the Southern Harz type of the German deposits. The saline beds were evidently precipitated in a gradually subsiding lagoon which covered parts of Barcelona and Lerida in Lower Tertiary times. ; The structure of the deposits makes their commercial development rather troublesome. At Suria’ the beds turn steeply over in a monocline, the dip of which is about 70°. They are then again brought near the surface by a fault, from which the beds continue to dip in the same direction but at a much reduced inclination. At Cardona the deposits are worked in the axis of a steep anticline, where the continuity of the beds has been repeatedly broken by faulting. Here the chief potassium salt is sylvite, which occurs in nearly pure seams. At Suria, however, the salts are more varied. Certain bands consist dominantly of carnallite, but generally there is intimate admixture with rock-salt, and occasionally layers of sylvinite appear. Numerous potash zones, alternating with rock-salt, and of variable thickness and value, have been proved, the aggregate thickness being equivalent to 60 feet of carnallite and 13 feet of sylvite. The complete extent of the Spanish potash field has not yet been determined, but it has already been explored over a belt more than 6 miles long, and consequently very substantial reserves may be anticipated. The first large shaft sunk by the Franco- Belgian Syndicate, which has a concession at Suria, has now been completed, and it is expected shortly to raise 1,000 tons of raw salts per day. That production was not commenced during at least the last year of the war was due mainly to German intrigues and political troubles, the details of which need not here be discussed. 1 EH. M. Heriot, Mining Journal, vol. exix, p. 753, December 15, 1917. (To be continued.) Dr. F. A. Bather—WNotes on Yunnan Cystidea. 255 II].—Norrs on Yunnan Cystipra. III. Szwocysrrs comParEp WIth SIMILAR GENERA. By F. A. BATHER, D.Sc., F.R.S. (Published by permission of the Trustees of the British Museum.) (WITH FIGURES 22-30 on PLATE VI.) B.—Comparison with Mazcacysris (continued). 4. The Thecal Openings. T is these which afford the justification for any comparison between Sinocystis and Megacystis. Those of Sinocystis are, it will be remembered (antea, December, 1918, p. 584), a transversely elongate peristome, a hydropore-slit approximately parallel to the peristome, a gonopore to the left of the anal plane, and a hexagonal or pentagonal periproct. These openings, though differing in details, are in number and position essentially similar to those of Aristocystis. Hitherto there has been much uncertainty as to the positions, and even the presence, of the hydropore and gonopore in Megacystis. It will here be shown that both are present, and that all four openings have much the same relations as in 3 : cS a a 3 g 3 wa | 2 5 2 District. 06) £ f eh et a = coir! 5 S eo Org 2 g BE AL ie = Se | ees el PS ¥ a z Siecle ca = Within isoseismal 7 35 10 2 11 17 23 2 Between as 7 and 6 46 tl i) 9 13 14 2 A a @ os ® | Gi 5 9 8 6 9 2 3 7H I) eee 47 14 10 5 8 13 3 Outside Fey 46 15 15 8 0 15 0 Omitting the references to miscellaneous sounds, the types of passing vehicles, thunder and wind are of long, and the others of short, duration. The percentages of reference to types’ of long * 308 Dr. C. Davison—The Stafford Earthquakes of 1916. duration for the above districts are respectively 47, 64, 77, 73, and 77; showing that as the distance increases from the origin, the sound becomes smoother and more monotonous. This is especially noticeable in the case of references to the third type, that of wind. Time-Relations of the Sound and Shock.—In the following table the figures under the letters p, c, and f indicate the number of records per cent in which the beginning or end of the sound preceded, coincided with, or followed, the corresponding epoch of the shock; and those under the letters g, e, and 1 show the number of records per cent in which the duration of the sound was greater than, equal to, or less than, that of the shock :— aegis Relative Beginning. End. : District. 8 Duration. pjec f | p Ne geelees te =|) Jl Within isoseismal 7 56 | 26 | 18 8 | 71 | 21 | 58 | 42) O Between a) 7 and 6 63 | 29 8 | 33 | 35 | 32 | 58 | 42} O i a Ge Eso 58 | 38 4 | 21 | 60 | 19 | 56 | 35] 9 i a 5 ',, 4 63 | 12 | 25 ae Whole sound-area 60 | 32 | 8 5) 25 | 51 | 24 | 57 | 38 It will be seen that the percentages for the beginning and end lend no support to the view, sometimes expressed on insufficient observa- tions, that the sound travels more rapidly than the waves which form the shock. Had this been the case, the figures for the precedence of the sound would have shown a very rapid increase with the distance from the origin. AFTER-SHOCK: JANUARY 15. Time of occurrence, 10.45 a.m.; intensity, 4; number of records, 7, from 7 places. A slight shock was felt at Alsager, Cheadle, Coton Hill (near Stone), Croxden (near Uttoxeter), Horseley (near EKccleshall), Huntley (near Cheadle), and Stone. With one exception, these places lie within the isoseismal 6 of the principal earthquake (Fig. 2). Alsager lies one mile to the north. From the distribution of these places, it seems probable that the epicentre is not far from the centre of the isoseismal referred to, and therefore lies between the two epicentres of the principal earthquake. The shock was a slight one, and consisted of a single series of vibrations. ORIGIN OF THE HKARTHQUAKES. From the forms and relative positions of the isoseismal lines, we obtain the following elements of the originating fault: (1) its mean direction lies between E. 22°S8. and E.28°S., or about E. 25°S. ; (2) its hade is tothe north; and (8) the fault-line must pass within a short distance (about a mile or two) on the south side of the centre of the isoseismal 7. This position for the fault-line is, however, given on the supposition that the fault-surface isa plane. If the ¥ Dr. C. Davison—The Stafford Earthquakes of 1916. 309 surface were curved and increasing in inclination to the horizon as it approached the surface of the earth, the position above given would be the line in which a tangent-plane at the depth of the focus to the fault-surface meets the surface of the earth, and this ought to lie some distance to the south of the actual fault-line. This apparent displacement of the presumed fault-line is specially characteristic of deep-seated earthquakes. In British earthquakes, the only test that we possess of the greater or less depth of the seismic foci is the less or greater rate of decline in the intensity of the shock at the surface. A rough test of this rate of decline is the area enclosed within the isoseismal 4 for shocks of different intensity at the epicentre. For earthquakes of intensity 7, this average is 22,000 square miles in England and Wales, and less than 1,000 square miles in Scotland ; for those of intensity 5, the corresponding . figures are 780 and 450. Thus, the rate of decline of intensity outwards from the epicentre is much more rapid in Scotland than in England; and this implies that the average depth of focus is much less in Scotland than in England and Wales. Now, Scottish earth- quakes which cannot be correlated with known faults are very rare. In English and Welsh earthquakes it is quite an exception to be able to associate an earthquake with a known fault; and, in the few cases in which this is possible, the area within the isoseismal 4 is always small. Itistherefore not surprising if we cannot point to any definite fault in the case of the Stafford earthquake.* Should we not rather look on the results of the earthquake investigation as adding to our knowledge of the structure of the crust at a depth which is far beyond the range of the field-geologist’s methods ? Returning to the Stafford earthquake, the positions of the two epicentres cannot be determined with accuracy, but, from the form of the isoseismal 7 and the course of the synkinetic band (which must pass between the epicentres), it follows that the eastern epicentre must lie about two miles north-east of Stafford and the western epicentre about twelve miles north-west of Eccleshall. The distance between the epicentres would thus be about 8 or 9 miles, which differs little from the average (10 or 11 miles) for British twin-earthquakes. For very many years, possibly for centuries, there has been no perceptible movement along the earthquake fault. Then, suddenly, two earthquakes occurred so closely together that the later could not possibly be a consequence of the earlier, for it took place before the earth-waves had time to traverse the interfocal region. The only movement that could produce such practically simultaneous displacements is one of rotation. We may conceive the earthquake- fault as cutting transversely a crust-fold (Fig. 3) the crest C and trough T of which are separated by a distance of about nine miles. If a small step took place in the growth of the fold, that is, if the 1 Close to Eecleshall there is a small post-Triassic fault (Geol. Surv. map, sheet 22, S.W.), which is parallel to the longer axis of the isoseismal 7, and hades to the north. If this fault were continued to the east it would occupy the position assigned to the fault-line by the seismic evidence. 310 Dr. C. Davison—The Stafford Earthquakes of 1916. crest and trough were to become more pronounced, simultaneous movements of the fold—the crest C to C’ and the trough T to T’— would occur, and these movements would be accompanied by a rotation of the median limb, the central portion M of which would undergo no displacement. Thus, we should have two foci, CC’ and Tl", entirely separated by the interfocal region about M. Moreover, the forces which give rise to an earthquake of this kind must act at right angles to the direction of the fold, that is, parallel to the direction of the fault. Fig. 3. It is evident that movements of this kind would suddenly increase the stress within the median limb, and the effect of this increase would be a sudden movement of translation of the median limb into some such position as that indicated by the line C’M’'T’, thus giving rise to a simple shock with its epicentre in the interfocal region of the twin-earthquake. The interval between the twin-earthquake and its first after-shock varies from a few hours to several weeks. In the Stafford earthquake, the observations of the after-shock are insufficient to determine its epicentre with precision; but it was probably due to a translation of the median limb of the fold about fifteen hours after the occurrence of the twin-earthquake. On tHE RELATIONS BETWEEN THE STAFFORD EARTHQUAKE OF 1916, THE Derby Earraq@uakes or 1908, 1904, ann 1906, anD THE LEICESTER EARTHQUAKES oF 1893 anp 1904. On March 24, 1908, a strong twin-earthquake occurred in Derbyshire,’ one focus being near Ashbourne and the other about 3 miles west of Wirksworth. The distance between the foci is thus about 8 or 9 miles, and the direction of the longer axis of the isoseismal 7 is N.33° EK. This earthquake was followed on May 3 by an interfocal after-shock, the direction of the longer axis of the isoseismal 5 being N.25° EK. On July 3, 1904,’ another strong twin-earthquake occurred, in which the same foci were in action, the southern focus being 13} miles east of Ashbourne, and the northern probably in the same position as in 1903. The 1 Quart. Journ. Geol. Soc., vol. lx, pp. 215-32, 1904. 2 Quart. Journ. Geol. Soc., vol. lxi, pp. 8-17, 1905. Dr. C. Davison—The Stafford Earthquakes of 1916. 311 distance between the foci is 6 or 7 miles, and the direction of the longer axis of. the isoseismal 6 is N.31° HK. Eight hours later, on the same day, the earthquake was followed by an interfocal after-shock, the direction of the longer axis of the isoseismal 4 being N.27° EK. Lastly, on August 27, 1906,! a much slighter twin- earthquake occurred in the same foci as the earthquake of 1904, the direction of the longer axis of the isoseismal 5 being N. 25° E. The mean direction of the earthquake fault is thus about N. 28° E., which is nearly, but not quite, at right angles to that of the Stafford earthquake fault. Again, on August 4, 1893,? a twin-earthquake of intensity 5 occurred in Leicestershire. The principal epicentre lies 2 miles S.S.W. of Loughborough, and the direction of the longer axis of the isoseismal 5 (which surrounds this epicentre only) is E, 30°S. The second epicentre lies close to the village of Tugby, and is 17 miles EH. 34°S. of the other. There can be little doubt that both impulses originated along a single fault, the direction of which at the north-west end is EK. 30°S., and at the south-east end about E. 40°S. A later earthquake, which occurred on June 21, 1904, in the south-eastern focus only, shows that the direction of the fault there is H. 42°S8. Now, if the fault-lines of the Stafford and Derby earthquakes be produced to meet, their point of intersection is 9 miles from the eastern focus of the Stafford earthquake and 18 miles from the southern focus of the Derby earthquakes. In both earthquakes, the distance between the foci is 8 or 9 miles, which is therefore the distance between the crest and trough of acrust-fold. Thus, the point of intersection of the two fault-lines is ata distance of half a crust-fold-length from the nearer focus of the Stafford earthquake, and of a whole crust-fold-length from the nearer focus of the Derby earthquakes. Also, if the fault-lines of the Derby earthquakes and of the Leicester earthquake of 1893 be produced to meet, their point of intersection is about 10 miles from the other point of intersection, about 8 miles from the southern focus of the Derby earthquakes (that is, about half a crust-fold-length from either), and about 26 miles from the north-western focus of the Leicester earthquake and 43 miles from its south-eastern focus (that is, about three and five half crust-fold-lengths from the two foci).° If we may assume that the earthquake-faults are at right angles to the folds, to the growth of which the earthquakes are due, it would seem that the crust at a depth of a few miles below the counties of Stafford, Derby, and Leicester, is corrugated in two systems of folds approximately at right angles, and that the axes of the north-and-south folds exhibit a fan-shaped arrangement or 1 GEOL. MAG., Vol. V, pp. 301-3, 1908. 2 Quart. Journ. Geol. Soc., vol. lxi, pp. 1-7, 1905. > It will be noticed that the distance between the foci of the Leicester earthquake is about double that between the foci of the Derby and Stafford earthquakes. Possibly, the foci of the Leicester earthquake occupy the crests of successive folds ; but there are difficulties in the way of such an explanation. 312 ~ B. Smith—Glacial Gravels of Corwen. continued easterly twist in successive lines, the direction being about N.25°E. through the Stafford foci, N. 28° E. through the Derby foci, and N. 30° E. and N. 42°. through the Leicester foci. The existence of this deep-seated double system of corrugations may perhaps explain another peculiarity of British earthquakes. Dividing them into three classes of strong, moderate, and slight earthquakes, according as the areas embraced by the isoseismal 4 are greater than 5,000, between 5,000 and 1,000 or less than 1,000, square miles, it appears that the average length of focus for strong earthquakes is 12} miles, and for moderate, earthquakes 13 miles. Slight earthquakes are divisible into two groups, in one of which the focus is 9 miles or more in length, and in the other 6 miles or less in length. ‘The average length of focus for the former is 12 miles, and for the latter (omitting a large number of very slight shocks) 4} miles. If we leave out of account the second division of slight shocks, which are of the nature of local creeps, it follows that the average length of focus in all three classes of earthquakes is very nearly the same, about 123 miles. IiJ.—Tse Lare Gractan Gravers or THE VALE oF EDEYRNION, Corwen, Norra Watrs. By BERNARD SMITH, M.A., F.G.S. (WITH A MAP.) HE Corwen gravels were described by D. Mackintosh, forty-three years ago, in a paper ‘‘On the mode of Occurrence and Distribution of Beds of Drifted Coal near Corwen, North Wales”. ? He attributed the gravels to an interglacial marine submergence and claimed that the coal found in them was derived from the outcrop of Coal-measures near Ruabon, twelve miles due east of Corwen. ~ In the present communication a correlation is made between the Corwen gravels and certain gravels of Late Glacial age formed during © the melting stages of the North Welsh valley glaciers. A brief description of these gravels, as a preface to our correlation, seems advisable in view of the fact that no general account of them has ~ been published. ° : Reasons are given for assuming that the drifted coal, found at Corwen, was derived from a local concealed outcrop. Late-Glacial Gravels.—In many of the valleys of North Wales, such as the Dee, Ceriog, Tanat, Vyrnwy, and Severn, especially in the more mature parts of their courses through the mountains, the recent alluvium is flanked at intervals by terraces of gravel,® derived chiefly from the boulder-clay which previously clung to the valley slopes, and still floors the valleys over long stretches. These terraces have usually been regarded as post-glacial, and mapped as ordinary 1 “‘ Characteristics of British Earthquakes’’: GzoL. MacG., Vol. VII, pp. 410-19, 1910. 2 Quart. Journ. Geol. Soc., vol. xxxii, pp. 451-3, 1876. > Summary of Progress for 1914 (Mem. Geol. Surv.), 1915, p. 17; and for 1915 (Mem. Geol. Surv.), 1916, pp. 11, 12. B. Smith—Glacial Gravels of Corwen. 313 alluvium. But just as the highest terraces of the Trent valley between Newark and Nottingham! have been shown to be late- Glacial, so also the highest terraces of these mountain valleys are now recognized as having been formed during the retreat of the ice. They are the equivalents of the present day sheets of gravel formid alongside, and at the snouts of, the retreating valley-glaciers of the Yakutat Bay region of Alaska. \ YE . Dy MAP 1 1207 / Aik See se Ni lg DERWEN ei Us of the Dee Valley near \ z / Up ea eed, ae Corwen, and the Giwyd Valley near Derwen. \ Caréoniferous Limestone ~ Alluvium i Scale , . g 7 5 bt a YF GWYDDELWERN ery \ SA WOR a ie Se ¢ YY \ ? ga Wonye Re ease res ee —— COR yap f = oo Map showing site of Gravel Plain near Corwen. In broad open valleys, like that of the Trent, the late-glacial terraces are of fairly regular height and level surface; but in mountain valleys, such as those of the T'anat and Vyrnwy, they appear at various heights above the recent alluvium—here 20 feet, there 40 feet—even when the remnants of a dissected terrace are * Geology of the Country between Newark and Nottingham (Mem. Geol. Sury.), 1908, pp. 73-6. 314 B. Smith—Glacial Gravels of Corwen. fairly close together. At some points, where a valley was winding, narrow and constricted, the escaping glacial waters distributed the débris irregularly, the resulting terrace being of varying height and uneven surface and occasionally pitted with kettle-holes.1 Where the valleys debouched on the plain, for example where the Vyrnwy leaves the mountains at Llanymynech, the gravel is spread out as a huge apron or fan several miles across,? the grade of material becoming finer and finer, and the fan progressively thinner, towards its margins. Near the mountainous headwaters of the rivers these gravels are usually thin and patchy, and their surfaces are not far above the present alluvial level, whilst the floor (boulder-clay or ‘‘solid’’) upon which they rest is also sometimes above this level. As we fellow them down stream towards their lower mountain course the terraces rise higher and higher above the alluvium. Where the rivers debouch on the plain the terraces descend quickly to stream- level. Thus the gradient of the late-glacial streams was flatter than that of the present stream. The gravels themselves also are actually thicker in the middle or lower part of the mountain course than near the headwaters or in the fan. This result was undoubtedly due to the aggrading power of the streams, which were choked with more débris than they could conveniently carry. The dissected terraces that now rise prominently in bold bluffs above the present rivers are not primarily due to any uplift of the land, but to the sinking of the thalwegs of the present streams to a curve consonant with their present volume and rate of flow. During this process the late-glacial gravels have been attacked and redistributed as post-glacial terraces at one or more lower levels. The gravels are varied in grade and character, in places being fairly clean boulder beds with good-sized erratics, which gradate through finer gravel and silts or clayey gravel into a more clayey deposit that cannot be distinguished easily from the parent boulder- clay. Usually the gravels are roughly stratified, the constituent beds often dipping at steep angles; but.in some places they appear to be tossed together in disorder. The Corwen Gravels ( General).— At Corwen there lies an open plain, surrounded by an amphitheatre of mountains, near and north of the confluence of the River Alwen, which flows from west to east, with the River Dee, which flows from south-south-west to east-north- east and then turns due east past Corwen and traverses the famous Vale of Edeyrnion. The plain is made up of two physiographical units. On the south it consists of the recent flood-plain of the above-mentioned rivers, north of which is a gently undulating plain of gravel extending 13 miles in the direction of Gwyddelwern and averaging about 550 feet above sea-level, or 100 feet above the alluvial plain of the Dee at Corwen. The two features are separated by a steep bluff. The gravel plain is about 14 miles wide near the rivers, but } Summary of Progress for 1915 (Mem. Geol. Sury.), 1916, pp. 11, 12. 1 (Ojo, Clin 1s We B. Smith—Glacial Gravels of Corwen. 315 narrows northward in the direction of Gwyddelwern. It also. occurs on both flanks of the flood-plain in the valley east of Corwen. This plain is probably floored by boulder-clay, because its surface is diversified by low patches of undrained marshy ground where the erayels are thin or absent, not through denudation, but apparently because they have never been deposited there. From our own observations this boulder-clay, on the hill-slopes near Corwen and in the Dee valley farther east, comes out from beneath the gravels and river deposits and ascends to higher levels. Corwen Gravels (Details).—We may take it that Mackintosh’s description of the succession of the deposits is, as usual, correct. The sands and gravels and the occasional irregular kind of brick-clay over-lie boulder-clay with beds of coarse gravel. The cuttings along the railway north of Corwen, examined by Mackintosh, are now, unfortunately, grassed over to a great extent; butitis still clear that an irregular deposit of layers and lenticles of unevenly-bedded gravels and false-bedded sands and silts on silty loam (? brick-clay) is over- lying boulder-clay which appears here and there at about rail level. The beds dip almost due east. A section on the left bank of the Nant Fawr, south of the line, contained masses of gravelly clay, loam, and clayey g gravel like boulder-clay with intercalated sands. About halfa mile N.N.E. of Corwen, at the junction of the Carrog road, north of the river, with the by-road to Tan-y-gaer at the east end of the bridge over the railway, 2 feet of soil with boulders rests n 2 feet or more of partly stratified loam with stones, on 3 feet of pebbly gravel. The loam is generally grey or grey-brown, but contained small patches of brick-red sand, rusty or yellowish-red sand, and streaks of bluish clay. The stones were partly rounded, partly subangular. Many were of igneous rocks, but none were of types that might have come from the Irish Sea area. There were also occasional cherts and sandstones. Similar deposits extend as far north as the railway cutting south of Gwyddelwern, where, at about 580 feet O.D., they die out above the boulder-clay.! Turning again to the Dee valley we note that in a pit in the gravel terrace near Groes-faen, about 530 yards west of Carrog Church, the beds were unlike ordinary river gravels. The dip is in all directions, and the deposit is silty, sandy, and gravelly in streaks and patches, often inclined at high angles, Some patches are clayey, others of fine loam with a feel like French Chalk or Fuller’s Earth. The following section was exposed at one point in the south side of the pit :— My Shine Coarse gravel and pebbles . ; : about Bi (O Grey silt and sand 5 o 6 Pale fine gravel ia 6 Light- heaven finely laminated clay iw 1 0O 1 In a north-easterly direction towards Bryn Eglwys the boulder-clay is associated with very little sand or gravel, but makes good drumlin scenery. The exceptions are some morainic sands and grayels in the valley at Bryn Eglwys and near the southward bend of the Afon Morwynion, north of the Carrog Gap. 316 B. Smith—Glacial Gravels of Corwen. Amongst the boulders were some of subangular pink crinoidal limestone up to 1 foot in length, fossiliferous rocks from the Bala Beds, subangular cherts, and fragments of local Silurian rocks. About 300 yards west of Carrog Church there is a large natural hollow or kettle-hole ; whilst on the south side of the river, west of Nant Llechlog, the gravels are distinctly moundy and sandy, and possess nothing like the nearly flat surface we should expect if they were normal river deposits. ‘The sand is greyish and the boulders are usually of local rocks, with some of carboniferous limestone, and a few of cherty rock. Corwen Gravels (Probable Origin).—The deposits described above, in their general mode of occurrence, their arrangement and com- position, resemble fluvio-glacial accumulations rather than those of an ordinary river. They appear to have been formed during the retreating stages of the Dee valley glacier as marginal and terminal gravels that choked the valley, through which the glacial waters swung from side to side in many interosculating channels. The general direction of glaciation at the height of the Ice Age, as shown by strie in the neighbourhood, was from W.S.W. to E.N.E. or S8.W. to N.E., with local variations in direction due to the topography of the lower ground. ‘The Corwen amphitheatre, formed by the confluence of the Dee valley with several tributary valleys, was filled at a later stage in the glaciation with a mass of ice from which tongues were thrust out eastwards down the Dee valley, north-eastward up the Morwynion (Bala Fault) valley in the direction of Bryn Eglwys, and northward past Gwyddelwern over a low col into the Clwyd valley near Derwen. A prolonged halt or very slow melting and retreat of the ice in the Corwen amphitheatre favoured the accumulation of a broad outwash fan covering an area of over two square miles, the drainage escaping by the Dee valley. The Gwyddelwern Valley.—The deep trench-like valley, two miles in length, crossing the watershed between the Dee and the Clwyd north of Gwyddelwern, and now traversed by the Corwen- Ruthin railway, is at first sight suggestive of a gorge cut by overflow waters from a glacial lake impounded in the amphitheatre to the south. However, no water carrying much gravel seems to have entered the Clwyd valley; and since the valley bottom now forms a water-parting covered by boulder-clay, and the western side is anatural escarpment capped by Wenlock Grit, it is more probable that the valley is a natural pre-glacial feature’ accentuated by the scour of the lower layers of ice moving into the Clwyd valley, and at, the time we are considering it was filled by a stagnant melting mass of ice cut off from its base on the south. Had it been used as a channel for overflow water, the boulder-clay at least would have been cleared out and there should have been a steady descent of the floor from Gwyddelwern to the Clwyd valley. The floor, on the contrary, rises north of Gwyddelwern to a mile-long stretch at above 600 feet O.D. before it descends to about 550 feet in the Clwyd valley. 1 In pre-Glacial days a south-flowing tributary of the Dee must have risen in this valley and have made a near approach to capturing the head-waters of the Clwyd. B. Smith—Glacial Gravels of Corwen. 317 Source of Coal in the Gravels.—The occurrence of coal débris in _ the gravel varying in size from large lumps to fine dust, is a point of great interest. Mackintosh records it (i) in a roadside section immediately east of the Carboniferous Limestone Quarry (Hafod-y- ealch) about a mile anda half west of Corwen; (ii) in a railway- cutting some distance east of Corwen and not far from Carrog Station; (ili) north of Corwen, near to where the Ruthin railway -erosses the River Dee—this was the principal locality. He was also assured that coal could be found at many other places around Corwen. After diligent search the author failed to find any coal, probably because of the overgrown state of the cuttings, but residents in the neighbourhood stated that coal had been found in the gravels. Mackintosh rejected the hypothesis that there might ,be a concealed outcrop of coal-bearing beds in the neighbourhood, and suggested that the coal was drifted some twenty miles up the winding Dee valley from the neighbourhood of Cefn or Ruabon, during ‘an interglacial submergence. ‘his idea of submergence cannot be maintained. The coal might have been derived from three possible sources : (1) from the Vale of Clwyd; (2) from the Ruabon district; (3) from a local outcrop. 1. This direction of transport may be dismissed sone. South of St. Asaph the movement of ice was from S.W. to N.E., and all waters due to melting ice flowed northward. 2. Any movement of coal from Ruabon must have been against the general direction of glaciation, and must have been caused by ice-bergs or water moving up the Dee valley, and escaping in a south-westerly direction, owing to a huge ice-dam (Irish Sea Ice) across the Dee valley below Llangollen. There is no evidence for this as far as I am aware, nor has it been suggested by my late colleague, Mr. L. J. Wills. The boulders in the Corwen gravels include no rocks from the Irish Sea basin. 38. Thus we are thrown back upon the theory rejected by Mackintosh, namely, that the ‘‘ very-little-waterworn”’ fragments of coal could only have come from some now-buried or completely destroyed outcrop in the vicinity. If we imagine that the Carboniferous Limestone at Hafod-y- calch near Corwen was formerly succeeded by ‘‘ Millstone Grit” (Cefn-y-fedw Sandstone) and a considerable thickness of normal Coal-measures, it may be difficult to believe that there is a local outlier of the latter that has escaped detection north of the Bala Fault; but when we remember that in the Vale of Clwyd the so-called Millstone Grit is wanting and the Coal-measures are represented by thin purple shales and sandstones” with occasional thin coal-seams (one of which had shafts sunk along it) resting upon the highest beds of the Carboniferous Limestone, belief in the occurrence of Coal-measures near Corwen, which is only slightly farther west, is strengthened. In the quarries at Hafod-y-calch 1 The Geology of the Neighbourhood of Flint, Mold, and Ruthin (Mem. Geol. Surv.), 1890, pp. 10-16. 318 Dr. F. A. Bather—Notes on Yunnan COystidea. the higher beds of Limestone dip north-eastward at 45° beneath the alluvium of the River Alwen. We may, therefore, be justified in assuming on stratigraphical grounds, and on the evidence of the gravels themselves, that the coal in the latter may have been derived from some portion of an outcrop that was demolished by glacial action. ‘The erosion may have removed the stratum entirely if it were quite a small wedge between the limestone and a branch of the main Bala Fault concealed by the alluvium on the northern side of the outcrop. Our experience shows that such little wedges of rock, clipped in at the junction of important faults like that which traverses the Dee valley from Corwen to Llangollen and the Bala Fault, are the rule rather than the exception. The shales and sandstones in such an outher might have yielded some of the material of the finer silts and loams and sandy patches in the late-glacial beds. Whether the sandstones were purple might depend upon whether they were overlain by any Triassic Sand like that which succeeds the purple sandstone in the Vale of Clwyd. No boulders of purple sandstone have been found (it is very friable material), yet the patches of brick-red Triassic-like sand, mentioned above as being found in the drift, are distinctly suggestive. How far the Trias overspread the Carboniferous rocks in this area is not known, but it is fairly certain on other evidence that the ~ Bala and other large structural faults were in action both before and after the deposition of the Trias. 1V.—Nores on Yunnan Cystipga. III. Szvocrsris comPARED WITH SIMILAR GENERA. By F. A. BATHER, D.Sc., F.R.S. (Published by permission of the Trustees of the British Museum.) B.—Comparison with Inzeacysris (continued). 4. The Thecal Openings. b. The Periproct. 1* Megacystis the periproct—which S. A. Miller always called the mouth—lies between adoral cirelets II and III, being bounded by the two posterior facet-bearing plates and the posterior interradial, i.e. 8 of Adorals II, also by 2 or 8 of Adorals III, making 5 or 6 plates in all. The number 5 is the more usual; it occurs in M. aspera, faberi, gorbyt, indianensis, ornatissima, ornata, parvula, parva, perlonga, plena, scitulus, and spanglert, also in British Museum specimens EK 7631, —33, —385, —37, —38, ?—39, —40, —42, — 44, —45, —74, —76, —77, E. 16167, and E 16168 (see our figs. 24, 25, antea). The number 6, due to an additional Adoral III, Js found in M. baculus, commoda, splendens, and perhaps gyrinus, also in E7630, —34, —36, ?—75, and E16171 (see our figs. 22, 23, 28, 30, antea). This does not seem to be a difference of such constancy as to be relied on for the discrimination of species. It is the sole character distinguishing Miller’s J/. commoda from his Jf. gorbyi, not to mention UW. scitulus and J. parva, which may be younger stages of Dr, F. A. Bauther—WNotes on Yunnan Cystidea. 319 the latter species. Similarly such specimens as E 7631, I 76385, E 7688, and EK 7644, each with 5 plates, cannot otherwise be distinguished from EK 7636 with 6 plates; while E 7630 and E 7634 with 6 plates are otherwise the same as E 76338, E 7640, E 7642, E7677, and E 16168, each with 5 plates. There are a few exceptions to the preceding general statements. S. A. Miller (1879) regarded the additional plate in JL, dbaculus as an AdorallV rather than III, but, since his figure lends no particular support to this view, the species has been included in the above list. In I. gyrinus (fig. 30) it does seem probable that an Adoral IV enters into the periproctal frame, but it is obscured. In MM. spheroidalis (fig 27) there are at least two additional plates in the Ad. III series; indeed the drawing shows three, but the small triangular plate is possibly a corner separated by a crack. ‘Thus the periproct is surrounded by 7 or 8 plates; but this extra number is correlated with the spheroidal shape of the theca rather than with any structural peculiarity in the periproct. There may also be a reduction in the number of plates. The specimen figured by R. R. Rowley (19038) as ‘* Holocystites papulosus?’’ shows the posterior Adoral II descending on each side of the periproct so as to meet thetwo Adorals III and to exclude the facetted plates from the periproct, which therefore is surrounded by only three plates. By a similar downgrowth in J. subovata the right posterior facetted plate is excluded from the periproctal frame, which here consists of four plates. This is an exaggeration of a tendency which this species shares with Jf. ornatissima (fig. 25) and If. papulosa, and which resultsin an obliquely elliptical periproct with its long axis passing from the left facetted plate to the right of the two Adorals III. In the otherwise similar J/. aspera this. tendency is not manifest, so that the long axis of the periproct is horizontal. The numerical reduction discussed in the preceding paragraph is due to elimination of a plate or plates from the periproctal frame. Specimen E7632 presents a reduction to four plates owing to the presence of only one Ad. III in the frame; and this one, being a large plate, may be taken to represent the usual two, whether there has been fusion or no. In other respects this specimen resembles E 7631 and EK 7635, and the reduction can only be regarded as a meristic individual variation. Other exceptions to the general statement are caused by modifica- tions in the posterior interradius of circlet Ad. II. Thus, in E7639 the left facetted plate is excluded from the periproctal frame by the intercalation of a plate between it and the posterior Ad. II, so that there are 9 Ad. II instead of 8; correlated with this is an extra plate in circlet Ad. I, apparently cut off from the left posterior Ad. J. This intercalation of plates is, oddly enough, not accompanied by an additional Ad. III, so that the number of plates surrounding the periproct is still 5. In E 7675, a somewhat similar intercalation of an Ad. I and an Ad. II only just eliminates the left posterior facetted plate from the periproctal frame, and is accompanied by an additional Ad. III, so that there are 6 plates in the frame 320 Dr. F. A. Bather—Notes on Yunnan Cystidea. and only just escape being 7; in this specimen, however, the three posterior Ad. III are relatively much narrower than in the more swollen orspheroidal E7639. In these cases the additional Ad. II seems to be due to nothing more than the development of a suture separating the prolongation of the left posterior facetted plate from the body of the plate, for the sake of greater flexibility ; in harmony with this the adjacent Ad. I also becomes longitudinally divided, but its suture in both specimens is a very close one and not easy to see. In no specimen of Degacystis recorded or known to me are the anal valves (or periproctals) preserved. The usually rectilinear outline of the opening, with its slightly rebated sides, denotes that the periproctals were,as in Sinocystis, triangular plates. Their number may be inferred from the number of sides possessed by the periproct. This is not necessarily or invariably the same as the number of bounding plates. Occasionally the sides of the periproct, and consequently the periproctals, do approximately correspond with the margins of the bounding plates in both position and number, e.g. E 7634, and Miller’s figures of IZ. parva and I. seitulus, his fig. 6 of IM. commoda (not the figure copied antea fig. 23), and less closely his figure of 2/. gorbyi. Frequently the sides correspond with the plates in number but not in position, and in this case the angle at which two sides meet lies not at the suture between two bounding plates but at some distance from it, so that the free margin of the dlate is notched. ‘This notching may affect one or more or even all plates; thus E 7640 and E 16168 have each 5 sides and 5 bounding plates, and all the latter are notched. Usually, however, the correspondence is fairly exact with Adorals I1;it is the Adorals IIT that tend to be notched. When the numbers correspond the notching may be confined to the left-hand Ad. ITI (e.g. E 7642, EB 7645, E 7677); when there are 6 sides and 5 plates, the notching extends usually to the right-hand Ad. III (e.g. E 7638, E 16167) orit may instead affect the left Ad. II (as in E7687). Inthe cases (probably rare) when 6 plates surround a 5-sided opening, the median Ad. III has a con- _spicuous median notch (e.g. E 7636). Sometimes it is impossible to identify any precise number of sides, since all angles seem rounded off so as to produce a circular or elliptical opening. This is particularly noticeable in the JL. ornatissyma series (see p. 257) and in If. spherowdalis. Possibly in such forms the triangular periproctals were separated from the periproct margin by a flexible finely-plated membrane. In J. aspera and in the specimen described by Rowley as ‘‘ Holocystites papulosus?”’ (see p. 257) the periproct has a quad- rangular outline and may have been closed by four valves. The preceding facts show that, though there were certain tendencies in the several groups of species, still there was no fixity. Neither the number of the periproctals nor that of the sides of the periproct can be regarded as a specific character. Possibly the sides of the periproct may originally have corresponded with the margins of the bounding plates, and this correspondence is usually retained in the adoral half of the periproct; but the variability in the third adoral circlet may have conflicted with the persistent conditions in the Dr. F. A. Bather—WNotes on Yunnan Cystideu. 321 second circlet, and so induced shiftings or numerical changes in the opening between them. In Stnoeystis the number of the periproctals was more fixed, being six in SS. Joczy: and S. yunnanensts, five in S. mansuyt (antea, 1918, p. 511). A rough correspondence with the bounding plates is shown in Reed’s pl. i, fig. 3, but the available evidence is not enough to warrant any general statement. The greater irregularity and variability of the thecal plates in Sinocystis, as well as the absence of any connexion between the periproct and the relatively fixed Adorals II, suggest that the constitution of the theca had here little influence on the periproctals. The preservation of the periproctals in the fossils of Sinocystis indicates that they were more solid, or more firmly united to the frame than in MMegacystis. Therefore, in Sinocystis the number of the periproctals dominates the bounding plates, whereas in JJegacystis it is more affected by them. ‘To some extent the periproctals and the bounding plates form two systems, each subject to its own hereditary and environmental influences, and therefore liable to be brought into conflict. ec. The Hydropore and Gonopore. When the various openings in MMegacystis were discussed by P. H. Carpenter in 1891 (J. Linn. Soc., Zool., xxiv, pp. 48-50), on the basis of Miller’s figures, he recognized all four openings in M. commoda, though in general he regarded the openings as confined to peristome, periproct, and ‘‘nephridial opening’”’ [ =hydropore ], and in some cases (e.g. If. elegans) to the two former alone. His view was that the periproct served as an osculum, embracing the gonopore as arule and in some cases the hydropore as well. Jaekel (1899) did not specifically mention or figure the hydropore and gonopore in his Zrematocystis, but, since he regarded the presence of both those openings as characteristic of the Aristocystide, he must at any rate have assumed their presence in Zrematocystis. Miller’s figures and descriptions are rather insecure evidence, and there are reasons for believing that the opening observed in a number of species cited by Carpenter, and regarded by him as “excretory” or ‘‘nephridial’”? and ‘‘equivalent to the fourth opening of Aristocystis and Gilyptosphera’’, i.e. what we now take as the hydropore, is really the gonopore, and that the hydropore, though present, was not observed. The reasons for this belief are first a morphological argument, secondly comparison with other genera, thirdly actual observation of the British Museum material. The morphological argument depends on a structural feature to which attention has not, it seems, previously been directed. ‘This is the tendency in so many of these primitive echinoderms for the hydropore to be a slit crossing the suture between two plates. So it is in Hdrvoaster (Bather, Studies in Edrioasteroidea, Geol. Mag. 1914, p. 168, pl. xi, fig. 2), Arzstocyst’s (Barrande, 1887, Syst. Silur.,; vol. vil, pl. 1x, figs: 25 3, 6, 135 “Bather, 1906, Paleont. Indica, II, 3, p. 9.), Stnocystis (antea, 1918, p. 535), Pleurocystis (Jaekel, 1899, Stammesges. d. Pelmatozoen, pp. 101, 188), Schizocystis DECADE VI.—VOL. VI.—NO. VII. 21 322 Dr. F. A. Bather—WNotes on Yunnan Cystidea (Bather, 1900, Treatise, p. 61, fig. xxv), Cryptocrinus (op. cit., p. 70, fig: Xxvli, 2, after Jaekel), and other genera. “The gonopore, on the other hand, is a simple hole, as often as not ' through the middle of a plate. It further differs from the hydropore in being frequently (perhaps normally) closed by valves, and these, as in the case of the periproct, give it a rectilinear—often pentagonal —outline. It is so small itself, and its valves. are so minute, that the structure often cannot be made out, even if the pore itself be not obscured by the processes of petrifaction. It seems probable that both hydropore and gonopore originally emerged between thecal plates, and that they were subsequently surrounded by the plate-stereom in the same way as the podia of echinoids have become surrounded by the ambulacral plates between which they originally passed. ‘The gonopore of the Cystidea, being the outlet of a single gland, has remained a simple pore and has been wholly occluded by a single plate. Itis not so easy to see why the hydropore should affect two plates. The curious bilateral folding of the stone-canal in Asteroidea and the alleged occasional paired hydropore of the embryo might suggest that here was a relic of the bilaterally symmetrical Dipleurula. On the other hand, the obliquity of the hydropore-passage in Hdrioastery and elsewhere shows how two plates may be involved without any suggestion of duplicity. The essential difference between hydropore and gonopore seems to be the conversion of the former into a filter through the formation of numerous minute pores connected by a ciliated channel on the exterior. This channel extended from the original opening in both directions. For the present this must be taken as a fact, but we have still to explain the direction followed and its frequent regular curvature. In later forms these primitive features were obscured by the excessive folding that produced the characteristic madreporite. If the preceding statements be accepted, we are provided with a touchstone enabling us in most cases to decide which of two visible openings is the hydropore, which the gonopore, or, in the case of only one visible opening, to say which of the two itis. For example, in Chetrocrinus constrictus Bather (19138, Trans. R. Soc. Edin., XLIX, ui, p. 445, fig. 51), the ‘‘ extended pore’’ that crosses ‘‘the curved suture”’ is probably the hydropore, and the ‘‘ poriferous elevation at the other end of the plate’ is probably the gonopore ; the converse interpretation was tentatively suggested in the memoir. In the ‘‘ Treatise on Zoology’’ some openings are perhaps lettered wrongly: in Echinosphaera, p. 53, fig. xiv, and Sphaeronts, p. 72, fig. xxxviil, the tri-valved opening marked M, and in Protocrinus, p. 75, fig. xly, 1, the pore through the plate marked M, should all be the gonopore. ‘The test will be applied to Megacystis later. In comparing Iegacystis with other genera, Carpenter went on the belief that there was no hydropore or gonopore at all in Agelacrinus, the Caryocrinidae, and A/alocystis, and no separate gonopore in seven other genera that he mentions. Therefore he was ready to admit similar conditions in Megacystis. Since then we have learned that there is a hydropore in the Edrioasteroidea (S. R. Dr. F. A. Bather—Notes on Yunnan Cystidea. 323 Williams has just claimed to have detected it in Agelacrinus itself), the Caryocrinidae, and MMalocystis; also that there is a gonopore, probably or certainly with a hydropore also, in Caryocystis, Cryptocrinus, Cheirocrinus, Orocystis, Sphaeronis, and Sphaerocystis (here Schuchert, 1904, calls it the hydropore, although he acknow- ledges another opening as ‘‘madreporite”’). In a word, it is no longer safe to ascribe the apparent absence of these openings from any cystid to anything but our ignorance and the extreme difficulty of dispelling it. Thus the argtiment from other genera, so far from supporting the views of Carpenter, points to the presence of both gonopore and hydropore in all species of Megacystis. Lastly we come to the evidence of the British Museum specimens. These, even when they are closely similar in all other respects, do, it is true, present some interesting variations in the shape and distribution of these openings, but both openings ean nearly always be detected. — £7640 E7677 BLES, Fic. 31.—Hydropore-sutures in Megacystis. These all occur in specimens of M. gorbyz character, and show the replacement of the hydropore-slit by a sinuous suture between the posterior Adorals I. x 10 diam. The Hydropore is plainly seen in ten specimens, and faintly suggested in about six more. In the remainder it has been obscured by crushing or by encrusting organisms, or the plates are absent. Normally it appears as a narrow groove or a dark line, indicating a slit, crossing the suture beween the two posterior Adorals I at right angles, just outside the peristome rim. In E 16168, identified as H, scitulus by 8. A. Miller, the length of the slit is 1:2 mm., and this seems to be above the average. In E 7688 the slit seems to be continued on the right into a sinuous suture, which reaches the right posterior facetted plate and so bisects the right posterior Ad I. Sometimes the slit is on an eminence, as in E 76383, ? E 7636, E 7642. All these specimens are, like J. settulus, of IL. gorbyi character. In E 7678, astrongly pustulate form, the position of the hydropore seems indicated by a rather irregular rim (antea, fig. 29). In a few of the specimens where the hydropore is less plain, the existence of some such structure is suggested by a remarkable sinuosity of the suture (fig. 81). In E 7636, a dark spot indicates the actual pore, and the suture just here makes a slight bend. In E 7644 the suture is sharply bent where it crosses the hydropore- slit. In E 7640 no opening can be detected, but in the middle of its course the suture takes a sharp semicircular curve to the left, and 324 Dr. F. A. Bather—WNotes on Yunnan Cystidea. all this tract forms a gentle eminence. In EK 7677, there isa similar sharp, but less regular, curve to the left at the aboral end of the suture, and the rest of the suture is waved; there is no obvious eminence. In E 7637 there are three sharp curves to the left and three to the right, beginning with a small one at the aboral end on the left and increasing in swing towards the oral end; although there is no trace of a pore or of an eminence, it cannot be doubted that this exaggerated sinuosity does in some way represent the foldings of the hydropore. The variations here described bear little or no relation to differences that might be taken as specific. They show how easily one may overlook the indication of a hydropore, especially when it is merely a passage between two plates; and they warrant the conclusion that a hydropore is present in all species of Megacystis, though previously recorded only in J/. commoda, M. gyrinus, and M. hammellr. The Gonopore appears in one of two distinct places. In eleven specimens out of the eighteen in which it is visible it pierces the posterior Ad. II (antea, figs. 24, 26). It may be near the centre or in either the adoral or aboral half of the plate, but always lies to the left of the median line (EK 7631,—32,—35,—36,—38,—4], . —44,—73,—74,—75). In E 76389, where there are abnormally two posterior Ad. II, the gonopore is on the left-hand one. In the remaining seven specimens the gonopore is on the right slope of the left posterior facet-boss, sometimes very close to the brachial facet itself, e.g. ‘7mm. distant in E 7634, E 7640, ‘6mm. in FE 16168, ‘5mm. in E 7680, ‘4mm. in E7677, and -8mm. in E 7683 (antea, fig. 22). This position is more than a mere crossing over the suture between the facet-bearing plate and the interradial. Only in E 7642 is the opening as near to that suture as it is to the facet, the respective distances being each 1:3mm.; in this particular case the left posterior facet is curiously widened in the direction of the gonopore, as though stretching out to meet it. Remembering that in the Crinoidea the genital strand passes into the arms, some may see here the beginning of a similar relation. The brachia of a crinoid, however, are outgrowths of the theca and contain extensions of the body-cavity; in this they differ fundamentally from the brachioles of a cystid, which are purely epithecal structures, and contain, so far as one can see, no such extensions. Carpenter (1891, p. 49) drew attention to a somewhat similar variation in two of Barrande’s examples of Aristocystis bohemica : ‘‘In one of them the distal opening, which I regard as genital, is on the very edge of the anal aperture, while in the other it is nearly halfway up towards the peristome’’; it remains, however, on a plate distinct from that connected with the brachiole. From Miller’s descriptions or figures it is inferred that the gonopore is on the posterior Adoral II in nine species, viz., JZ. baculus, commoda, fabert, hammelli, ornata, parvula, rotunda, scitulus, and splendens (antea, figs. 28, 28); near the left posterior facet in four species, viz., UU. gyrinus (fig. 30), plena, pustulosa, and subglobosa. It has not been recognized in any other of the described Reviews—Military Geology and Topography. 825 species. These numbers, as well as those drawn from the British Museum specimens, suggest that the position on post. Ad. II was the more usual. Since either position is found in specimens otherwise identical, the character cannot well be taken as diagnostic of species. Neither does there seem any convincing reason for regarding it as a secondary sexual character. When clearly seen, the gonopore has a pentagonal outline, indicating that it was closed by five valves. In E 7632 it has a slightly raised rim which appears toothed, perhaps owing to the preservation of portions of the valves. In E 7636, the opening is hexagonal. When the pore pierces post. Ad. II, it is generally flush or on a very slight eminence; the latter feature is seen in Ei 7631 (antea, fig. 24). When the pore is near the facet, it is always on a rounded eminence, which in E 7630 and E7684 is so pronounced as to simulate the root of a young pelmatozoon. In two of the specimens the gonopore seems to be double. In EK 76380 (fig. 22), where it is on an eminence near the facet, there is close beside it another smaller eminence with a pore. In E7635, where it is on the left side of post. Ad. II, the appearance is rather - obscure, but there certainly seems to be a smaller opening to the right of the main pore, and barely separated from it. As compared with Scnocystis, the position of the gonopore is here slightly more definite, and in all cases is well above the periproct (not on a level with it) and nearer to the subvective system. (To be continued.) RAV IWS. T.—Mrutrrary Grotocy anp TopocrapHy. Prepared and _ issued under the auspices of the National Research Council, Division of Geology and Geography. Edited by Herpert E. Gregory, Ph.D. pp. xv + 280. New York: Yale University Press. London: Oxford University Press. Price 5s. 6d. net. pees book was specially prepared in response to many requests for guidance in the presentation of courses, required by the Committee on Education and Special Training of the War Department, for the training of officers for the new American Army. The list of collaborators in its preparation is a long and distinguished one, including thirteen University professors and lecturers and several well-known officers of the Geological Survey of the United States. A modest statement appears in the preface: ‘‘The book is the result of a preliminary effort, and its authors hope that it will be a nucleus about which will gather material for a more complete volume.” The fact that the American War Department recommended that officers should be taught geology and geography is worthy of attention. When the entry of America into the War was decided upon, American officers visited the Western Front to study conditions and methods in order to profit by the knowledge gained for the 326 Reviews—Military Geology and Topography. training of their new Army. ‘They were at once struck by the great increase, as compared with former wars, in the numbers and varieties of maps and also by the far greater employment of mining. At one period the Western Front was to all intents and purposes in the hands of the mining engineers of both sides, mine and countermine determining the success of costly local operations. It was therefore natural to assume that the study of mining would form a greater part of the education of the military engineer of the future than it had done in the past. The study of mining is closely linked with that of geology. Again,it was found that geological experts were attached to the headquarters of the Armies, the most highly organized branch being found in the German Army. There were also special branches of the engineering staff dealing exclusively with water supply. The authors had, therefore, a wide field to cover, and by the nature of the case were compelled to be very concise. They have acquitted themselves very well, for the book contains just as much geology and topography as the military engineer—that jack of all trades— need know, clearly and attractively presented. The subject first studied is that of rocks and other earth materials. The scheme adopted is to describe the rock and give an account of , its occurrence, then to note its practical utility, as for example in the preparation of concrete. Rock weathering is then shortly described as its direct bearing on military work is only slight. Next streams, lakes, and swamps are considered, and examples, from the War and history, of their influence on military campaigns are frequently inserted. The study of water supply is gone into pretty thoroughly, occupying fifty-two pages. This attention is indeed merited, good and plentiful water being most important to the health and comfort of troops in any campaign. Theory and practice are skilfully intermingled. The chapter on land forms, in which field of study American geologists lead the way, enables the reader to appreciate the forms characteristic of the different kinds of rocks. The portion of the book devoted to map-reading and interpretation is not quite so good as our own Army handbook on the subject, except that the interpretation is treated from the geological point of view. It is alsointeresting to note that the authors make no attempt to explain geological map-reading; probably they consider this should be left to the expert. . The last chapter deals with the economic relations and military uses of minerals. Throughout the text numerous references to more advanced works by American authors are given. The book is clearly printed, profusely illustrated with excellent photographs and diagrams, and is reasonable in price. In spite of the fact that the book was written for the special purpose of training officers for the War just concluded it would be of great value to officers, particularly to those of the Royal Engineers, as the essentials of their requirements of geology and topography are collected together under one cover. B. Liearroor. Reviews—The Origin of Serpentine. 5p T1.—Tuer Onion oF SERPENTINE: A HisrortcaL anp CoMPARATIVE Stupy. By W. N. Benson. Amer. Journ. Sci., vol. xlvi, pp. 693-731, 1918. OR some years past Professor Benson has made a comprehensive study of serpentine rocks, arising from his work on the Great Serpentine Belt of New South Wales. He has had the advantage of working at Cambridge, with the advice and assistance of Professor Bonney, and has also visited many European localities and con- sulted some of the leading Continental authorities and examined their material. The results of his investigations are brought together in this valuable paper, which begins with a short but clear account of the historical development of the views of the leading petrologists on the genesis of serpentine. Starting from the now universally accepted view that serpentine rocks are altered deep- seated peridotites, consisting mainly of olivine and pyroxene, the author shows that in many cases, at any rate, the process of serpentinization is essentially of a pneumatolytic nature, analogous to a certain extent to the formation of greisen, water and carbon dioxide being the chief agents concerned ; coarse-textured veins of serpentine and olivine occasionally found in such rocks show some resemblance to granitic pegmatites. Serpentine with mesh-structure (chrysotile) is usually found in undisturbed regions, while antigorite is specially characteristic of high pressure; the latter is sometimes formed by dynamic metamorphism of the former. It appears that although serpentinization is usually due to the pneumatolytic action of the residues of the same magma that gave rise to the original peridotite intrusion, nevertheless there have often been several intervening intrusions of differentiates from this magma, ranging even to acidic composition, hence the process of serpentinization may appear to be due to a granitic intrusion; however, geologically speaking, the interval is short and the alteration is completed before the end of the same orogenic and eruptive phase. It is also con- sidered possible that in certain cases a peridotite which has escaped hydration by its own magmatic waters may subsequently be changed to serpentine by the action of deeply circulating epigene waters. At any rate, it is clear from the facts stated by Professor Benson that it is no longer permissible, as has been done by many writers, including the present reviewer, to consider serpentinization as an effect of weathering now in general operation near the earth’s surface; it must for the future be relegated to the category of deep- seated late-magmatic phenomena, which for want of a better name are generally classified under that blessed word ‘“‘ pneumatolytic”’. Tey dale day I11.—Brprae tit Frymarxens Geotocr. By O. Horrepauy. Norges Geol. Undersok, No. 84, with English Summary. pp. 314, with 21 plates and 2 coloured maps. Kristiania, 1918. S the result of careful field-work extending over nearly six months in the years 1914-17, the author shows that Dahll’s classification of the rock-systems of the extreme north of Norway Be 8 Reviews—Falklandia. cannot be maintained; his Gaisa system in particular includes a large number of rocks of different ages. fs The oldest rocks in the south of the district are of pre-Cambrian age, comprising hornblende schists, quartzites, and crystalline magnesian limestones; towards the west, in Jori, is a region of less advanced metamorphism with slates, dolomites, and volcanic rocks resembling those of the Kiruna district in Sweden, while east of the River Tana the country is mainly composed of gneisses and granites; both of these types are probably younger than the schists of the south. The oldest Paleozoic zone in Finmarken resting on a peneplain of erosion is a shale with Platysolenttes antiquissimus, a fossil found in many places in the Lower Cambrian of Scandinavia and the Baltic region; this is supposed to be part of a Cystidean. ‘his zone is clearly a continuation of the Hyolithus zones of Sweden and Norway. Above this comes the very thick Porsanger Sandstone with shales and dolomite, the latter enclosing laminated structures called by the author stromatolites and referred by him to chemical precipitation possibly brought about by alge. ‘These structures and the silicified layers in the dolomite strongly recall the characters of the Durness Limestone, and the series is assigned to an Ozarkian—Canadian age. Unconformably above the Porsanger Sandstone comes a younger series with conglomerates and tillites, formerly included in the Gaisa Series; the tillites of the Varanger Fjord were well described by Sir A. Strahan in the Quarterly Journal for 1897. ‘he author concludes on what appears to be good evidence that these deposits are of Ordovician or possibly Silurian age. All these rocks are again overlain in the Alten division of the district by the mylonitic rocks of the Caledonian thrust zone. It was formerly believed that these overthrust rocks were of pre- Cambrian age, but there is no evidence to support this view, and it is concluded that they are simply highly metamorphosed repre- sentatives of the unaltered Paleozoic rocks below the thrust. The resemblance to the general succession as seen in the North-West Highlands is obvious, and this memoir is of great interest on account of its bearing on the problems of British stratigraphy. _ TV.—Farxtanpia. By J. M. Crarxz. Proc. National Academy of Science of U.S.A., vol. v, No. iv, pp. 102-8, April, 1919. iE the valuable monograph published in 1913 by the Geological Survey of Brazil (Fosseis Devonianos do Parana), Dr. J. M. Clarke included a discussion on the paleogeography of the austral lands in Devonian times. He pointed out that the extent of the Southern Devonian shore faunas indicated the union of Gondwana- land and Antarctis during Devonian times. ‘The Devonian of these latitudes is a unit both in life and sedimentation. In the present short paper Dr. Clarke proposes the name ‘‘ Falklandia” for the ‘continental land which, during the Devonian period in the occidental parts of the Southern Hemisphere, preceded Gondwana- land and Antarctis’’. It is considered that other names, such as Frech’s ‘‘South Atlantic Island”, which have been suggested for the Pre-Gondwana austral lands, have been founded on insufficient evidence. Reviews—The Tin Field of North Dundas. 329 V.—Tar Tin Fiery or Norra Donpas (Tasmania). By H. Conder. Geol. Surv. Bull. No. 26. 96 pp. and 4 maps. Hobart, 1918, (W\HIS area consists of a region of slates, sandstones, grits, and conglomerates, with volcanic tuffs, their early Paleozoic age being proved by the discovery of some badly preserved graptolites. The mineralization appears to be due to the intrusion of a granite magma of Devonian age, which gave rise first to porphyroids, then to the main acid mass with a basic marginal facies: certain masses of diabase may be of much later date. ‘he metalliferous deposits belong to several different types, as follows: quartz-tourmaline lodes, quartz lodes, pyritic and pyrrhotitic lodes, and dolomitic lodes, with other less well-defined types. ‘lhe chief minerals are ores of tin, lead, zinc, and silver, together with pyrite and pyrrhotite. VI.—Fossiz CockroacHeEs, MONG Mr. Bolton’s energetic efforts to seek out all the Carboni- ferous Cockroaches, we note the Manchester Museum publication, No. 80, describes those specimens obtained by Mark Stirrup from Charles Brongniart. ‘These came from Commentry and are now in the Manchester Museum. Among them is a fine dragon - fly, Megagnatha odonatiformis. To these forms have lately been added a series from the Pennsylvanian of the United States, described and figured by Cockerell in the Proc. U.S. Nat. Mus., liv, 1918. Eight in number, they comprise two new genera, Cobaloblatta and Ptilomylacris. VII.— Annvat Reporr or rue Dirgcror oF THE GroPHyYsICAL Lazporatory, WASHINGTON, FOR THE YEAR 1918. ({\HE publication under review is the last of a series of Annual Reports which we owe to Arthur L. Day as Director of the Geophysical Laboratory of the Carnegie Institution. It must be a source of great gratification to Day to realize the high position which the Geophysical Laboratory has won for itself in scientific regard in the course of a comparatively few years. The present Annual Report leaves untold the story of the year’s progress achieved in the laboratory, for nothing but war work has beenattempted. It gives, however, a most valuable résumé of papers written by members of the staff and published in various American scientific journals. These papers, it is explained, are for the most part records of researches in progress at the time of the entry of the United States into the War. The summary thus afforded exactly meets the requirements of geologists the world over. It is an easy matter to turn from it to the journal containing the particular paper to which more detailed reference seems desirable. It is to be hoped on this account that the Annual Reports have a wide circulation. Thirty-three papers in all are considered. Several are concerned with laboratory technique. A few, again, relate to matters of pre- dominantly physical or chemical interest, as, for instance, the Planck radiation law, the place of manganese in the Periodic Table judged 330 Reports & Proceedings—Geological Society of London. by the colour of its chemical compounds and the high-temperature specific heats of platinum, silica, and the alkali felspars. Three papers deal with glass. One of them, by N. L. Bowen, is entitled ‘‘The significance of Glass-making to the Petrologist”. The summary given is as follows :— Contrary to certain claims that have been made, glass-making processes offer no support to the belief in liquid immiscibility among silicates, nor to the belief in a significant density stratification in a mass wholly liquid. They do, however, suggest the importance of gravity acting on a mass partly solid and partly liquid, and emphasize two stages: (1) that at which there is much liquid and little solid, and (2) that at which there is little liquid and much solid. In magmas these two stages are probably those during which the most significant results in the way of differentiation are accomplished. Bowen’s paper is a valuable contribution to a difficult subject. Field experience, especially in Mull, has led the present reviewer to favour the opinion that gabbro and granophyre are sometimes immiscible for a short range of temperature before crystallization sets in in earnest. Evidence pointing in this direction is often wanting even in the field, and under certain experimental conditions it might well be absent, owing, for instance, to such complications as metastable miscibility. Various other papers treat the side of petrological inquiry that receives its inspiration from the writings of Willard Gibbs. Thus, G. A. Rankin and H. KE. Merwin illustrate the temperature- concentration relations of the various crystalline phases in equi- librium with liquid in the ternary system MgO — AJ,0; — SiOz. Arising from this we find a reinvestigation of the melting points and stability relations of cristobalite and tridymite, carried out by John B. Ferguson and H. E. Merwin. Cristobalite is confirmed in its claim to be the high-temperature form of silica. Ferguson also gives an account of the equilibrium relations of the voleanic gases CO,, CO, SO,, and 8. Henry 8. Washington has quite a number of papers to his credit. Three refer to Italy, and include a consideration of the leucitic lavas as a potential source of potash. Of his other works may be mentioned a compilation and discussion of chemical analyses of igneous rocks, 1884 to 1913, and a new edition of his Manual of the Chemical Analysis of Rocks. He also gives an account of a method of calculating from chemical analyses of clays the mineral composition - “generally quartz, felspar, and kaolin”. No novel principle is involved, but the procedure is recommended as ‘‘of great simplicity and accuracy’’. ~ K. B. Batrey. REPORTS AND PROCHHDINGS.- I.—Grotoercat Socrery or Lonpon. May 21, 1919.—Mr. G. W. Lamplugh, F.R.S., President, in the Chair. The following communications were read:— __ 1. “The Silurian Rocks of May Hill.’ By Charles Irving Gardiner, M.A., F.G:S. With an appendix by Frederick Richard Cowper Reed, Sc.D., F.G.S. Reports & Proceedings—Geological Society of London. 381 The district of May Hill comprises a small area of ashy grits, which Dr. Callaway in 1900 considered to be of Pre-Cambrian age. The evidence now available does not seem to warrant any definite opinion as regards the age of these beds. Llandovery sandstones are extensively developed, and are of Upper Llandovery age. They consist of a lower division of coarse sandstones and conglomerates, and an upper one of fine sandstones. No beds of Tarannon age occur. The Woolhope Limestone is never thick, and fossils in it are very few. ‘The Wenlock Shales and Limestone show a normal development. The latter is very fossiliferous, and shows coral- masses in the position of growth. The Ludlow Beds are, in the main, of a brown sandy nature. No Aymestry Limestone is present, and the Ludlow Beds cannot be separated into an upper and a lower division. A bone-bed is seen at the top of the Ludlow Beds by the side of the road near Blaisdon. ‘This was described by H. E. Strickland in 1868, who saw it in the railway-cutting close by. Downton Sandstone occurs in the north of the district, where it is about 800 feet thick; but it is only some 11 feet thick near Blaisdon on the south. It is conformably overlain by Old Red Sandstone. The Silurian rocks are arranged in an anticline in the part of the district where May Hill is, but elsewhere show no such arrangement. On the north they are much broken by faults. Near Flaxley, in the extreme south, rocks from the Wenlock Shale to the Old Red Sandstone inclusive are overfolded. Dr. F. R. C. Reed describes a new species of Lichas from the Wenlock Limestone and a new variety of Calymene papillata. 2. “The Petrography of the Millstone Grit Series of Yorkshire.” By Albert Gilligan, D.Sc., B.Sc., F.G.8. Since the pioneer work of Sorby on this subject, published in 1859, the clastic deposits of the Carboniferous System have been unaccountably neglected by petrologists. The author has followed the usual methods of investigation, and has eollected a large number of pebbles and specimens from widely separated areas which have been examined microscopically. Numerous separations of the heavy minerals have also been made from all types of rock, varying from coarse conglomerates to shales, which occur in the series. Quartz-pebbles are dominant, and vary much, both in size and in colour. The largest are found in the coarse-grained beds at the bottom and top of the series. They often show double-sphenoid forms suggestive of derivation from mechanically deformed rocks, which inference is shown to be correct by the undulose extinction, the crenulate and mylonized structure seen when sections of them are examined in polarized light. Blue and opalescent quartz is very common, containing inclusions often of indeterminable character arranged in streams or rows: others contain liquid with movable bubbles, while needles and hair-like inclusions are also usually present. The quartz of the 332 Reports & Proceedings—Greological Society of London. finer material is similar in character, and the inclusions in the grains suggest that it has been originally derived for the greater part from such rocks as gneisses and schists. Felspar pebbles are abundant in all the coarse beds. They are dominantly microcline or microcline-microperthite, and when broken are found to be perfectly fresh, the lustre of the cleavage-faces being most remarkable. Blebs of quartz are frequently present in these felspars. In many of the rock-sections, grains of microcline and oligoclase, quite fresh and unaltered, are common. Fragments showing the intergrowth of blue or opalescent quartz and microcline are fairly abundant. Chert pebbles are plentiful in the coarse beds at the base of the series; they are also sporadically distributed throughout the upper beds, and in some of these oolitic structure has been Shsearetl One pebble of silicified oolite shows a microscopic structure strongly resembling a structure found in the Torridon Sandstone. A few fragments containing microscopic organisms have also been obtained. Mica is not plentiful in the coarser beds, but increases in amount with decrease in grade of the material. From the Middle Grits of Airedale a remarkable assemblage of pebbles has been obtained, including the following types: gneisses, granites, schists, quartz- and felspar-porphyries, quartzites, grits, sandstones, and mudstones. One of these pebbles has been recognized as the black schist associated with the Blair Athol-a-Nain Limestone of Scotland. Another pebble is doubtfully referred to the rhomb- porphyry of the Christiania region. The results of the investioations into the heavy mineral contents may be summarized as follows, dividing for this purpose the Millstone Grit Series into three more or less well-defined groups :— (a) Lower Division—Base of the Ingleborough Grit to the base of the Leathley Sandstone. (6) Middle Division—Leathley Sandstone to the base of the Flags below the Rough Rock. (c) Upper Division—Flags and Rough Rock. The minerals are in decreasing order of relative abundance :— (a) Coarse beds contain garnet, ilmenite and leucoxene, zircon, tourmaline, rutile, monazite and magnetite. Fine beds contain zircon, rutile, garnet, and tourmaline. (b) Coarse beds contain zircon, rutile, garnet, tourmaline, ilmenite and leucoxene, magnetite and monazite. Fine beds contain zircon, rutile, tourmaline, and garnet. Some of the separations from the shales of Otley Chevin were almost entirely zircons, only a few grains of other minerals being present. (c) Coarse beds contain garnet, ilmenite and leucoxene, zircon, rutile, tourmaline, monazite and magnetite. The Flags at the base of the Rough Rock contain zircon, rutile, garnets, and tourmaline. The monazite has been determined by spectroscopical and chemical tests. In view of the similar work which is being done among the younger sedimentary rocks, it is important to record that, although the author has not yet discovered staurolite in the Millstone Grit, he has found it to be common in some of the sandstones near the Reports & Proceedings—Geological Society of London. 333 top of the Coal-measures in Yorkshire, namely, Ackworth Rock, Pontefract Rock, and the Red Rock of Rotherham, and also in basement Permian at Conisborough. In Yorkshire alone, to which area for the greater part the researches have been limited, the Millstone Grit forms the surface of 840 square miles; while, if that which lies beneath the newer rocks and that represented by outliers on the Pennine Fells were taken into account, it must have extended over at least 2,000 square miles. If 1,000 feet be taken as its average thickness, the Yorkshire Millstone Grit would represent a volume of 400 cubic miles, the equivalent of a range of mountains 800 miles long, 1 mile high, and 1 mile wide at the base. The beds attenuate southwards, and the only possible conclusion from their stratigraphy, reached by Sorby, and later confirmed by Edward Hull and A. H. Green, is that the material was derived from a northern source. The evidence which the author has obtained corroborates this view. The ancient land-mass of the Midlands must be ssxelinaledl as a possible source for more than a small fraction of the material, both on account of the inadequacy of the area and on account of its lithological constitution. The Lake District was probably submerged in Viséan times, and for that reason could not have supplied material to the Millstone Grit. Further, the abundance of monazite in these beds and its absence from the granites of the Lake District, as shown by R. H. Rastall and W. H. Wilcockson, definitely exclude that area. Southern Scotland may have contributed to the homotaxial deposits farther north than Yorkshire, but inadequacy of area is again pointed out. Thus, by elimination of other areas for one reason or another, the author shows that the most probable source of the material lay still farther north in a land-mass of. continental extent, of which Scandinavia and the North of Scotland represent the remaining fragments. In these areas alone can the mineralogical demands of the Millstone Grit be satisfied, and the author institutes a comparison between the Torridon Sandstone and the Millstone Grit, which shows that their similarity of constitution is altogether too great to be merely fortuitous. He infers that, despite their disparity in age, they had a common source in that northern continent. That continent had probably been base-levelled in pre-Millstone Grit times, and the advent of this period was brought about by renewed uplift rejuvenating the rivers, which removed the old rotted soil-mantle and exposed fresh unleached rock. The extension of the land-mass across the North Atlantic would produce a monsoon type of climate, and the rock-débris broken up under semi-arid _ conditions, as seems clear from the extreme freshness of the felspars in the grits, would be swept along rapidly by floods to the deltas of the large rivers. The author concludes by postulating one such large trunk river flowing southwards from the northern continent, and receiving 334 Reports & Proceedings—Geologists’ Association. tributaries from what are now Northern Scotland and Scandinavia, debouching somewhere off the north-east coast of England, the deltaic material of which (now consolidated) forms the Millstone Grit. — I].—Gerotoetsrs’ Association. June 6, 1919.—Mr. J. F. N. Green, B.A., F.G.S., President, in the Chair. The following paper was read: ‘‘Old Age and Extinction in Hossils.’) By WV -7D- Vane. Se.). Gas: I. A Biological view-point. _ The phenomena of old age and extinction must affect our general biological views; and these, in turn, are reflected in our attitude towards these phenomena. Vitalistic (or automatic) and mechanistic (or environmental) views are contrasted, and emphasis laid on the former. An organism has tendencies, or potentialities, towards developing in definite and not in haphazard directions; and these tendencies become actualized during evolution. They are kept in check by inhibiting factors, and on the removal of an inhibition there is an outburst of evolutionary activity ; thus evolution is seen to be periodic. Potentialities tend to become exhausted on actualization ; but, before this happens, may lead to the exaggeration of a character which, in turn, may cause the extinction of a lineage. Homco- morphy is the expression of common tendencies or potentialities becoming actual along many divergent lineages. II. This view reflected on to the phenomena of old age and extinction in (a) Cretaceous cribrimorph Polyzoa; (6) Ammonites; and (c) Rugose Corals. III. The consequences of this view. A view which ignores, or at least slights, environmental influences is likely to overlook the truth in one direction as far as (so the author believes) a purely environmental or mechanistic view, such as orthodox Darwinism, overlooks it on the other side. As an organism is a synthesis of structure and function, so its structure is a synthesis of expression and impression —expression of potentialities and impression of the environment. A synthesis is not an aggregate, for it transcends the sum of its components. A transcendental theory of evolution would link the field of philosophical biology to the realm of general philosophy. CORRESPONDENCE. RECENT PAPERS ON THE DURHAM COALFIELD. Sir,—In the Gxoroeican Macazinr of April last (p. 163) I observed a paper by Dr. D. Woolacott relating to the above Coalfield, where he writes of “the little-known Ganister Series” of that district, and I wondered what might be the precise meaning he wished to convey by those words. ‘Three or four coal-seams belonging to that Series (i.e. below the Brockwell Seam) have been vigorously worked for the past thirty years or more. ‘The measures Correspondence—J. 1’. Stobbs. 335 have been sunk through and bored, perhaps in a hundred places, whilst scores of mining engineers, inspectors, colliery managers (whose success depends “largely on their detailed knowledge ot “the strata of their mines) are and have been engaged in the exploitation of these seams, and we may presume that the sequence must be fairly well known lithologically. And so far as one can gather from his paper, it is solely upon lithological evidence Dr. Woolacott bases his conclusion that the boreholes he describes were in the Ganister Series. The generic names of the fossil plants he gives are quite useless in Coal-measure stratigraphy, and his quaint note that ‘no trace of any characteristic fossil [italics are mine] such as Aviculopecten papyraceus was found” leads one to infer that he has. not followed recent paleontological work in the Coal-measures, or he would not place so much reliance for zoning purposes on the discovery of Pterinopecten papyraceus. It is to be hoped that Dr. Woolacott is. in possession of other evidence of higher diagnostic value to warrant his opinion of the horizon reached by the boreholes. A perusal of this paper has suggested a fair reason for the disinclination of some mining people to seek the assistance of the geologists. In the May issue of the Grorocicat Magazine (pp. 203-211). Drs. Trechmann and Woolacott were constrained “to put definitely on record” the fact of the occurrence of the zone of Anthracomya phillipst in the Coal-measures of Durham. ‘They omitted to mention that this had already been done in the following papers, viz. Grot. Mae., 1905, pp. 536-7, and Trans. Inst. Min. Engineers, vol. xxx, pp. 453-4, 1906, where the stratigraphical significance of the discovery was clearly stated. J. ‘I. Sroszs. STOKE-ON-TRENT. May 21, 1919. PRODUCTUS HUMEROSUS IN DOVE DALE. Sm,—I had the good fortune recently to meet with two specimens. of Productus humerosus (P. sublevis) in Dove Dale (Derbyshire). This discovery seems worthy of record in point of view of the fact that hitherto the species has only been recorded for the Midland area from Caldon Low (Staffs). ‘The Dove Dale examples occurred in a loose limestone block on the screes immediately below Reynard’s Cave. In general form the specimens are strongly convex, narrow, and smooth, resembling the narrow form from Caldon Low described in this Magazine for February, 1919, p. 64. The matrix, however, is quite unlike that of the Caldon examples. J. WiItFRip JAcKson. MANCHESTER MUSEUM. May 22, 1919. MOUSTERIAN FLAKE-IMPLEMENTS. Sir,—I notice that in my letter published in the GxonoercaL Magazine for May, p. 240, I am made to speak of ‘‘the earlier Paleolithic ‘ cave’ implements”, and of ‘‘a normal Chellean or 336 | Obituary— Alexander McHenry. Acheulean cave-implement’’. In both cases the word ‘‘cave”’ should be ‘‘core”. The mistake has no doubt arisen owing to a printer’s error. J. Rerp Morr. IPSWICH. May 27, 1919. OQ seep ASE uae ALEXANDER McHENRY, M.R.I.A. BoRN OCTOBER 24, 1843. DIED APRIL 19, 1919. Mr. A. McHenry was born on October 24, 1848, and died at his residence in Dublin, after a very short illness, on April 19, 1919, in his 76th year. His connexion with the Geological Survey of Ireland dates back to his appointment as a fossil collector under J. B. Jukes in 1861, and he had consequently completed forty-seven years of public service on his retirement under the age-rule in 1908. His last work in the field took him back to his native county of Antrim, where he reported on the interbasaltic iron-ores and bauxites for a memoir published in 1912. He was appointed Assistant Geologist in 1877 and Geologist in 1890. McHenry will be always remembered as a strong and zealous worker, ready to accept new views, and to test them in the elucidation of Irish geological problems. His unfailing consideration for others and his equable temper in discussion inspired the affection of his colleagues, and his contentions, which were never contentious, demonstrated the necessity for new research, even where they could not be sustained in their entirety. In 1878 McHenry was charged with the mapping of wild and difficult districts in Mayo, including Achill Island, and then, years later, he was facing similar problems in still more complicated ground among the Caledonian ridges of Donegal. He was associated with other geologists in the memoirs on the Giant’s Causeway area and on north-west and central Donegal, and in the production of a series of maps and memoirs on districts round the larger cities of Ireland, issued under Mr. G. W. Lamplugh’s guidance from 1903 onwards. In this series the detailed mapping of the superficial deposits was undertaken, and McHenry showed as much adaptability in this new work as he had shown in the revision of the Silurian strata of Ireland, or of the igneous rocks bordering on the Leinster Chain. The discovery that graptolitic zones proved the presence of beds of Llandovery or later age in many areas mapped as Lower Silurian (Ordovician) led McHenry, with characteristic enthusiasm, to the conclusion that very little Ordovician rock occurred in Ireland. Had he been able, in his later years, to undertake independent field- research, he would have critically examined some of the work that he had helped to publish, and would have usefully reopened the discussion of the succession of beds in the Dingle promontory, on which he has left valuable notes. G.A.J.C. WANTED and FOR SALE PETROLOGICAL and other MICROSCOPES, Microtomes, Spectroscopes, ete. BEST PRICES GIVEN. SEND FOR CATALOGUE. JOHN BROWNING (Estab. 1765), 146 Strand, London, W.C. 2. LIST OF BOOKS OFFERED FOR SALE AT THE NET PRICES AFFIXED BY DULAU & CO., LTD., 34-36 MARGARET STREET, CAVENDISH SQUARE, LONDON, W. 1. ARCHIAC (A. D’). Histoire des progrés de la Géologie de 1834-1859. 1847-60. S8yols. S8vo. MHalf-calf. £2 Qs. 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All Communications for the EDITOR should be addressed to R. H. RASTALL, Esq., M.A., F.G.S., Christ’s College, Cambridge. All letters for Dr. H. WOODWARD, F.R.S., may be sent to Tudor Cottage, Clay Hill, Bushey, Herts. Books and Specimens to be addressed to the Hditor as usual, care of MESSRS. DULAU & CO.. LTD. 34-36 MARGARET STREET, CAVENDISH SQUARE, Weel: STEPHEN AUSTIN AND SONS, LTD., PRINTERS, HERTFORD. _ tae gli Price 2s. eological Magazine Monthly Journal of Geology. —— WITH WHICH IS INCORPORATED™ mi § TE als GEOLOGIST. LE % aaa BY Gg ») 5 19719 0 NN WOODWARD, LL.D., IRR i ANS Sf Mus® 2=40 1 a ss AND — fia) Ne R. H. RASTALL, M.A. : ASSIS'ED BY Pror. J. W. GREGORY, D.Sc., F.R.S. ' | PRor. W. W. WATTS, Sc.D., F.R.S. Pror. J. EH. MARR, Sc.D., F.R.S. HENRY WOODS, M.A., F.R.S. Sir JETHRO J. H. VHALL, Sc.D., F.R.S. Dr. A. SMITH WOODWARD, F.B.S. AUGUST, 1919. CONTENTS :— Page REVIEWS. Page EDITORIAL NOTES..........06..00000.. 337 3 j Novitates Paleozoic ............... 374 ORIGINAL ARTICLES. Mesozoic Insects of Queensland ... 377 Non-German Sources of Potash Permian and Triassic Insects from (concluded). By Dr.A. HOLMES. 340 New South Wales .................. BYArd The Igneous Rocks of the Ash- en ose Om ; 3 s of Scandinavia ............ 378 prington Area. By Miss IL. H. GeGloss Gf Hosea’ Ba 379 MOWAT Tica to sctk he ooeti wate cE 350 BY a aU eB nade oc Dr. C. D. Walcott’s Researches on ~ the Appendages of Trilobites. REPORTS AND PROCEEDINGS. cin Lee wean: 359 Geological Society of London ...... 379 he Two fin pases OF Gtmuinet. Mineralogical Society ............... 382 RES Ae pee eee 364 Geologists’ Association ............... 384 Brachiopod Nomenclature Spirifer and Syringothyris. By Dr. J. CORRESPONDENCE. 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All Apparatus for Geology supplied. WATSON’S Microscopes are guaranteed for 6 years, but last a lifetime, and they are all BRITISH MADE at BARNET, HERTS. W. WATSON & SONS, Ltd. (ESTABLISHED 1837) 313 HIGH HOLBORN, LONDON, W.C.1. Works:—HIGH BARNET, HERTS. < THE STOLOC OAL, MAGAZINE. . NEW SERIES). (DECADE Vi. VOCAL No. VIII.— AUGUST, 1919. NOTICE OF CHANGE OF ADDRESS. All communications for the Editor of the “ Geological Magazine” should be addressed to R. H. Rastall, Esq., M.A., F.G.S., Christ’s College, Cambridge. Letters for Dr. Henry Woodward, F.R.S., to be sent to Tudor Cottage, Clay Hill, Bushey, Herts. Books and parcels, especially from abroad, may be directed to the care of the Publishers, Messrs. Dulau & Co., 34-36 Margaret Street, Cavendish Square, W.1. HDITORIAL NOTES. WING tothe release of many geologists and Government workers and the demobilization of old contributors, besides the addition of numerous new ones, we have received, during the past few mouths, a very large number of important and interesting articles, many of them on subjects of immediate topical interest, and therefore necessitating early publication, and several also needing plates and text-figures for their illustration. Some of our friends have kindly come forward and contributed towards the cost of these necessary but expensive additions to their articles, but owing to the present high prices it is not possible to meet all the requirements of authors in this respect and cover the cost of prcduction with our present circulation. The Grorocicat Macazine is not primarily a money- making proposition, nevertheless it is necessary to its continuance that it should at least cover its expenses, and obviously the more copies sold the better value can be given in return. Therefore it behoves our friends, the readers and well-wishers, to use every effort in their power to secure among their associates new subscribers and increase its circulation, which is as essential to the life of a periodical as to that of a living organism. A vacancy having arisen in the body of the Trustees of ‘‘ The Perey Sladen Memorial Fund” by the retirement, after five years of office, of Sir John Rose Bradford, F.R.S., the Trustees requested the President and Council of the Linnean Society to nominate a successor to the Trust; and they have, in compliance, chosen Dr. Arthur Smith Woodward, F.R.S., President of the Linnean Society, to fill the vacancy for the term of five years. * * % * * bo bo DECADE VI.—VOL. VI.—NO. VIII. 338 Editorial Notes. THe late Dr. S. P. Woodward recorded in his notebook, 1864: ‘The collection of the late Dr. John Woodward, the founder of the Chair of Geology in Cambridge, originally was kept locked, and a bond for several thousand pounds was given by the Professor for the security of the specimens. ‘I'wo auditors were appointed yearly by the University to go over the whole collection and compare it with the official catalogue to ascertain the safety of the specimens, and to report to the Vice-Chancellor, who entertained them and the Professor at dinner. ‘The dinner was paid for out of the Woodwardian fund, and the guests were required by the will to drink burgundy. ‘lhe collection consists of about 10,000 specimens, chiefly British fossils. By Woodward’s will the Professor must be a bachelor and a graduate of the University. The salary was £100, with a further sum for the audit and dinner. The University has lately raised the Professor’s salary to £300.” It is hardly necessary to add that this salary is now calculated on a more modern and generous basis. A uigHty successful dinner, in honour of those members of the Geological Survey and Museum Stati who have served with His Majesty’s Forces, was held at Anderton’s Hotel, Fleet Street, on the night‘of April 80, with Sir Aubrey Strahan in the chair. Forty- eight present and past members attended; of this number twenty have seen active service in one capacity or another. It is to be regretted that distance or other circumstances prevented any of the nine service members of the Edinburgh staff from being féted also by their colleagues. * * * # * Mr. Harorp Cox’s pamphlet, Zhe Coal Industry : Dangers of Nationalisation (Longmans, Green & Co., 1919, price 6d.), should be read by everyone, since there is not a single individual in this country unaffected by the present enormous increase in the price of coal. This rise in price is to a very large extent due to the spread among the miners of ideas based upon unsound premises. Mr. Harold Cox exposes very clearly the fallacies underlying the arguments put forward by the Fabian Society and various miners’ organizations deriving their ideas from that source, in favour of nationalization and bureaucratic control, and abolition of royalties. These arguments are shown to be in their way triumphs of irrelevancy and middle-class theorizing founded on out-of-date statistics and applied to problems affecting mainly the relations of capital and labour. It is impossible here to quote these points in detail, but the author’s comparison with the Post Office and his remarks on Government departments in general are well worth reading. It is categorically stated in a Fabian pamphlet on nationalization that the State would be able to supply coal at £1 per ton delivered to the cellar. In view of recent developments, largely due to State interference, this makes somewhat ironical reading. With regard to royalties, it is shown that with the present scale of taxation, the State already gets back more than half the total, and Editorial Notes. 339 that confiscation of royalties would be not only a breach of faith with those who have acquired a legal right in them, but also an economic blunder, as in countries where minerals are in theory national property the State does not appear to get as much as it does in Great Britain; and after all the total amount of royalties is but small in comparison with the actual value of the mineral output of this country. * % % ca % Av a Special General Meeting, held on June 25 last, the Geological Society of London decided to raise the annual contribution of Fellows elected after November 1, 1919, to three guineas per annum. ‘This step was rendered inevitable by the enormous increase in expenses of all kinds, and especially by the greatly enhanced cost of publica- tion of the Quarterly Journal and other literature issued by the Society. This is undoubtedly one of the most important functions of the Society, and some sacrifice is necessary on the part of geologists if its usefulness in this respect is not to be impaired. The cost of publication must in any case necessarily be very heavy in the immediate future, as a good deal of leeway still has to be made up in the Quarterly Journal and the index of current literature, and it remains to be seen whether the step already taken is sufficiently drastic. At the same meeting it was decided to adhere to the present hour for meetings, 5.80 p.m. This decision will rejoice the hearts of all those Fellows who live within a couple of hours or so of London. At the present time, it is no small under- taking to spend a night in town, owing to shortage of hotel accommodation. Residents within 70 or 80 miles of London can usually return home after an afternoon meeting, whereas an evening meeting makes this impossible. Those coming from further afield must in any case stay in town, hence the present arrangement possesses many advantages and does no harm to any one. It has the additional good feature of making a shorter day for the permanent officials, whose hours on meeting-days, under the old arrangement, were unreasonably long. A FINE collection of minerals of economic value was lately exhibited in London, on behalf of the Government of one of the Dominions. Even more interesting than the .specimens themselves was the knowledge of mineralogy displayed by the officials responsible for the preparation of the explanatory labels. The following are some specially illuminating examples culled from this source :— Apatite Sugar: Mineral sugar is a poisonous salt. Jlanganite: A mineral occurring in crystals. Molybdenite: A soft mineral containing a great deal of sulphur, often known as ‘‘amber mica’’. Galena: A lead ore, formed by the action of sulphur on a non-metallic element. Pyrrholite: Name means ‘‘fire-light stone’’, another variety of serpentine. J/menite: ‘Taken from Ilmen Hills. Composed of tartaric acids and oxides of iron. Sphalerite: Name comes from word meaning treacherous. Better known as ‘‘blende’’, which comes from a word meaning to dazzle—a sulphide of arsenic. ORIGINAL ARTICLES. —_>_—_ I.—Non-Grruan Sources oF Porasa. By ARTHUR HOLMES, D.Sc., A.R.C.S., F.G.S. Abyssinian Deposits.—During 1911 an Italian resident in Eritrea discovered a remarkable occurrence of potash salts in the Prano del Sale, near the provisional boundary between the Italian colony and Abyssinia. On account of its equivocal situation, development was somewhat handicapped during the early stages by Abyssinian hostility. Fortunately these preliminary difficulties were successfully overcome, and the deposit proved to be of great assistance to the Allied Powers during the war. The rate of production has gradually increased, and the estimated output for 1918 is stated to be equivalent to 50,000 tons of KCl. The situation of the deposit is indicated on the accompanying geological sketch-map by a black rectangle (due south of the Bay of Haoachil, and just touching the recently determined boundary) which marks the position of Mt. Dellol. The Piano del Sale, or “ Plain of Salt’, is a depressed region almost entirely below sea- level. It is, in fact, as indicated on the map by a dotted line,’ approximately bounded by the contour of sea-level. The depression is separated from the Red Sea, of which it is structurally a part, by the lavas and sediments of the Aden Series. On the west the edge of the Abyssinian plateau, carved in an ancient complex of meta- morphic and igneous rocks, constitutes the real western boundary of the Red Sea Rift, and forms one side of the funnel-shaped sunkland into which the East African Rift Valley opens out near Ankober. The Piano del Sale is itself the exposed basin-like surface of a gigantic saline deposit, in which the older beds are disposed around the periphery, while the younger beds outcrop at successively lower levels towards the interior. Beds consisting mainly of gypsum, and representing the earliest phase of deposition, outcrop conspicuously around the northern and eastern sides, and similar beds also appear on the western edge, opposite Mt. Dellol. Within the gypsum zone, and at a lower level, though resting upon it, is a wide expanse of rock-salt over 20 miles across, and generally free from alluvium. The level gradually drops until it reaches about 390 feet below sea- level around Mt. Dellol. This so-called ‘‘mount” is a rectangular mass consisting mainly of rock-salt, the summit of which is within a foot or two of sea-level. It has been weathered into curious castellated forms, so that when seen from a distance in the slanting rays of the sun it resembles a vast medieval fortress. At'the south-eastern corner of this curious edifice, in the heart of the depression, red and yellow masses of sylvite are exposed at the 1 For a map showing the relation of this area to the Red Sea and to the Rift Valley of East Africa, see G. Dainelli & O. Marinelli in Atlante d’ Africa, by A. Ghisleri, 1909, p. 139, fig. 6. The information from which the geological sketch-map was compiled was mainly obtained from this publication (see pls. xxxi, xxxii, and pp. 133-9). [3g ec = ~ Archipelago Dahalak 16 LOS Fatimari q Cae ahalak ris ebire Archean Mesozoic Plateau Aden Series of Gypsum Saline Complex. Sediments. Lavas. Lavas, etc., and Deposits Deposits Volcanoes. 7 Plain of Salt. GEOLOGICAL SKETCH-MAP OF PARTS OF ERITREA AND ABYSSINIA. Scale, 1 inch = 34 miles. 342 Dr. A. Holmes—Non-German Sources of Potash. surface. Over an area of 200,000 square yards sylvite has been proved to a depth varying from 2 to 5 feet. ‘he average content of KCl in this part of the deposit amounts to 80 per cent, while ~ locally the purer material exceeds 98 per cent of KCl. Small quantities of NaCl are present, and also traces of MgCl, bromine, and iron oxides. Surrounding the sylvite and extending over an area ten times as great, carnallite is found to a depth of 150 feet. This is the greatest depth reached by the boreholes, and even near the junction of the carnallite with the surrounding rock-salt the lower surface of the former had not, in 1918, been reached, suggesting a plug- or funnel-like mode of occurrence. The carnallite beds average from 25 to 15 per cent of KCl according to the depth, but it is possible, without difficulty or special plant, to prepare for export much richer material. The carnallite is exposed to the sun as it is dug, and at the relatively high temperature normal to the district it becomes unstable, and liquefies in its own water of crystallization. From the solution so produced most of the KCl is directly deposited, leaving a mother-liquor which is concentrated with respect to carnallite, but which is still unsaturated with respect to MgCl,. By allowing this liquor to flow away, a high proportion of the MgCl, is removed. ‘he first effect of the evaporation of the liquor is the redeposition of carnallite, and although it is stable in the presence of MgCl, solution, it breaks down as before when the MgCl, flows away. The process is allowed to continue on these lines until finally a residue containing over 80 per cent of KCl remains to be packed for transport to the coast. The saline deposit as a whole displays an unusually complete sequence, and is clearly the result of evaporation in an arm of the Red Sea cut off permanently or intermittently by the volcanic hills of the present coast. Associated phenomena, however, indicate that volcanic agencies have also contributed to the development of the deposit. A series of springsrises through the carnallite zone, varying in temperature from 50°C. to 90°C. These consist essentially of saturated solutions of MgCl,, with appreciable quantities of bromine and small amounts of sodium, potassium, and iron.’ At the north- eastern corner of Dellol a deposit of ‘‘brimstone’’ has been found, surrounded bya deep bed of ‘‘ flowers of sulphur”. ‘he latter mode of occurrence points indubitably to condensation of the sulphur, either directly from the gaseous state or from the interaction of gaseous sulphur compounds. ‘The hot springs, the sulphur deposit, and the abundance of volcanic activity in the neighbourhood add extraordinary interest to the area, and it is to be hoped that an authoritative description and interpretation may soon be forthcoming. The southern partof the Piano del Sale has not yet been thoroughly explored, and as it contains various focal points of depression there is a reasonable possibility that other areas of potash salts still await discovery. Political considerations are likely, however, to prevent development in this direction, at least for the present, since the ' The springs are described in an Italian paper by M. Giua, of which an English summary is published in the Journ. Soc. Chem. Ind., vol. xxxvii, p. R460, 1918. Dr. A. Holmes—Non-German Sowrces of Potash. 343 Abyssinians are very jealous of the economic invasion of their territory. The Dellol deposit itself is now definitely known to be within Abyssinia, though it is worked by an Italian Syndicate under con- cession from the Abyssinian Government. Conditions of labour are far from pleasant, as the region is one of extreme aridity, while the average temperature in the shade is over 120° F. Nevertheless, in spite of climatic difficulties, there were at one time nearly 8,000 men employed in mining the potash, making a road to the coast, and building a port at Fatimari, a tiny settlement on ‘the Bay of Haoachil, 46 miles to the north of Dellol.' Early in 1917 arrangements were made for constructing a light railway to Fatimari, and by now this should have taken the place of camel transport, for at the end of last year the track was rapidly approaching completion. For many of the details made use of in the above description I am indebted to Captain Cockerell, the Controller of the Department of Mineral Resources Development of the Ministry of Munitions, and to Mr. Henry C. D. Blattner, who spent some months in examining the deposit during the early stages of its commercial development. Narurat Brines. Since potassium salts are among the most soluble of the saline materials contained in natural waters, they become gradually concentrated as evaporation proceeds, and are finally deposited from the brines that he over the crystalline body already deposited, or from the mother-liquors that occupy its pores. In various arid regions there are more or less desiccated lakes from which potash-rich brines are extracted; notably in the United States and Tunis. Here also the salt-marsh of Salin-de-Giraud in the delta of the Rhone may be mentioned, though the output of KCl derived from the evaporation of its waters is comparatively small. Searle’s Lake.—The deposit to which this name is applied occurs in a depressed and elongated basin-like region in the north-eastern corner of San Bernadina County, California.* During the Glacial epoch the basin, which is nearly surrounded by abruptly rising hills, was occupied by a lake whose surface stood 640 feet above the level of the present floor. A firm but very porous sheet of white salts now lies exposed over an area of 12 square miles, and laterally the deposit extends still further beneath the surrounding mud-flats. Down to a considerable depth rock-salt is the chief mineral found, but below 12 to 20 feet trom the surface irregular layers are found rich in trona or thenardite, and rarely in sylvinite. The deposits have provided a rich suite of minerals, the genetic study of which, as yet scarcely begun, will rival in interest that of the Stassfurt salts. Except quite near the surface, the interstiees of the crystal ageregates—amounting to 40 per cent by volume—are occupied by a highly concentrated brine, and from this the American Trona Corporation extracts a number of salts, including KCl. The brine, which has the composition set forth in the table below, is known to x » African World, August 18, 1917. 2 A. de Ropp, Journ. ‘Ind. & Eng. Chem., vol. x, p. 839, 1918. 344 Dr. A. Holmes—Non-German Sowrces of Potash. amount to over 110,000 million gallons, averaging about 4 per cent of KCl, and, therefore, containing 24 million tons of that salt. COMPOSITION OF AMERICAN POTASH BRINES. : ; Searle’s Lake,| Jesse Lake,| Salduro Salt | Great Sait Saline Constituents. California. Nebraska. | Marsh, Utah.| Lake, Utah. TROD si ees ARE i aR 13-5 10-0 7-03 3-16 KoSO,. : oo 31-5 — == KeCO3 — 13-0 — — NACI HW Mian 46-3 = 81-04 75-91 NaoSO, Opie eH niete| 19-2 aaa 1-98 9-52 NEAOOR 5°75" 5 13-0 45-5 — — NaeB.sO7 . 10H2O 8-0 — — — CaSO, is — — 0-88 0-34 CaCO; — — — 0-15 MgCl. . — — 9-07 10-92 100-0 100-0 100-0 100-0 Percentage of salts m solution . . 35°8 19-3 27-1 20-0 During the evaporation processes, sodium carbonate and sulphate, and borax are produced, and finally crude potassium chloride (75 to 80 per cent KCl) is recovered. At the present rate of working, from 50,000 to 60,000 tons of the crude salt are produced annually, together with one quarter that amount of borax. Other American Brines.—In Nebraska an area of some 8,000 square miles is occupied by sand-dunes, interspersed with flat-bottomed lakes or salt marshes. These represent every stage of evaporation, from nearly fresh water to residual brines. he ‘‘lakes’”’ are generally underlain by green muds and beds of sand, the latter containing the whole of the brine when superficial water no longer remains. The potash-content varies from 9 to 35 per cent of the dry salts, and when commercial operations on the richer brines were undertaken in 1915, they met with such success that the following year’s results gave Nebraska first place in the United States as a producer of potash.! Jesse Lake*is the most important of the basins from which brine is pumped, and a statement of its composition is listed above. The sands of the dune area are rich in orthoclase and microcline, but in a semi-arid climate it is unlikely that much potash can have been derived directly from such a source. The richness of the brine in carbonates suggests that its dissolved contents represent an accumula- tion of wind-blown ashes from years of prairie fires, concentrated by intermittent surface drainage. In Utah potash was recovered from the brine of Great Salt Lake during 1916 and in later years, but, as the analysis shows, it is unlikely that the production can continue to compete with that from more favoured sources. In the Salduro Salt Marsh,? however, Utah 1 Eng. & Min. Journ., vol. civ, p. 827, 1917. ? E. E. Thun, Met. & Chem. Eng., vol. xvii, p. 693, 1917. > Eng. & Min. Journ., loc. cit. Dr. A. Holmes—Non-German Sowrces of Potash. 345 possesses a more valuable deposit which somewhat resembles Searle’s Lake; but here the salt crust is only 3 to 5 feet in thickness, and the brine is not only less concentrated than in Searle’s Lake but contains less potash relatively to the other constituents. Tunis.—South of Gabes (long. 10° E.), in the lowland of the Tunisian Shotts, a salt lake is worked for both bromine and potash. A product known as ‘‘sebkainite”’, which contains about 34 per cent of potassium, is obtained by solar evaporation of the brine. Com- mercial exploitation began in 1915, and the present rate of extraction is equivalent to over 1,000 tons of KCl per month. The plant now being installed will gradually increase the production to four times the present output, and will make possible the export of the pure chloride, refined on the spot from crude salt such as is now obtained. SALTPETRE, Deposits of potassium nitrate are generally of organic origin, but in Chile a small proportion is associated with the sodium nitrate deposits, and in Brazil a deposit has recently been discovered containing 89 per cent of KNO,. In the Kocene marls and limestones of Fergana in Central Siberia saltpetre has been found to the extent of between 2 and 5 per cent over a very considerable area, and as fuel (coal and petroleum) is abundant in the same district the conditions appear to be favourable for its extraction. India, however, is the only large- scale exporter of saltpetre, Behar being the chief district from which it is obtained. ‘The conditions of its formation are well described in the Keview of the Mineral Production of India, 1909-13, from which the following paragraphs are extracted ! :— ‘For the formation of saltpetre in a soil the necessary conditions are : (1) Supplies of nitrogenous organic matter ; (2) climatic conditions favourable to the growth and action of Winogradski’s so-called nitroso and nitro bacteria, converting urea and ammonia successively into nitrous and nitric acids; (3) the presence of potash ; and (4) meteorological coadinione suitable for the efflorescence of the potassium nitrate at the surface. An ideal combination of these necessary circumstances has made the Behar section of the Gangetic plain famous for its production of saltpetre. “In this part of India we have a population of over 500 per square mile, mainly agricultural in occupation, and thus accompanied by a high proportion of domestic animals, supplying an abundance of organic nitrogen. “With a population largely using wood and cow-dung for fuel, the soil around villages naturally would be well stocked with potash, and, finally, with a period of continuous surface desiccation, following a small rainfall, the sub- soil water, brought to the surface by capillary action in the soil, leaves an efflorescence of salts, in which, not surprisingly, potassium nitrate is con- spicuous. Under these conditions Behar has for many years yielded some 20,000 tons of saltpetre a year.’’ Ketp. Since the beginning of the eighteenth century seaweed has been utilized along various parts of the Scottish and Irish coasts as a source of potash and iodine, but owing to foreign competition the 1 Sir T. H. Holland & L. L. Fermor, Rec. Geol. Sury. India, vol. xlvi, pp. 210-15, 1915. 346 Dr. A. Holmes—Non-German Sources of Potash. industry had long before the war fallen to very small dimensions, and even since 1914 it has not been appreciably revived. The home contribution of potash during the war from kelp! was, indeed, barely sufficient to supply the KClO, required for the manufacture of matches. Along the Pacific coast the kelp industry has developed on an enormous scale under the impetus of the demand for acetone and potash that arose early in the war. Giant seaweeds are harvested directly from the sea by floating mechanical reapers. After the weed is dried and burnt, the resulting ash contains salts equivalent to about 15 per cent of K,0. As a method leading to potash recovery alone—that is, without the collateral separation of by- products—this process was found to be wasteful, and even when the ash was sold directly as a fertilizer it was not found possible to compete with other sources of supply. Consequently more economical methods of treatment have been devised, the most successful being that in which acetone is prepared as the main product, with potash as a by-product. At San Diego the seaweed is fermented in large bins, and the resulting solutions (containing crude acetic acid with KCl and iodine compounds) are collected. Calcium acetate is formed by neutralizing the acid with limestone, and by its ignition acetone is formed. Meanwhile potassium chloride and iodine are concentrated in the residual liquors, and are ultimately separated in a crude state. The three products taken together have provided satisfactory profits under war conditions, but the future stability of the industry is less certain, especially as, in common with Searle’s Lake, the site of production is far removed from the principal centres of demand.? Other Organic Sources.—The fact that 90 per cent of the potash used in Great Britain is devoted to fertilizing purposes, is clearly an indication that the plants which absorb potash from the soil may themselves be utilized for its subsequent replenishment. Among important crops, flax and potatoes in particular require large quantities of potash for continued growth. It is, however, not ‘possible to produce potash economically from waste vegetation except as a by-product in already established industries. Even in the lumber camps of Canada the wood-ash from saw-mills waste contains insufficient potash to justify its collection and treatment, and its only value is as a local fertilizer applied to the land directly.? In Belgium and Italy potassium salts (K,CO,, KCl, and K,SO,) are recovered from the residual liquors left after the treatment of molasses in beet-sugar factories. In the Caucasus district there was formerly a considerable local potash industry dependent on the 1 The ash or slaggy matter that remains when seaweed is burnt in a kiln for six or eight hours is called kelp; but in the United States the weed is kelp, and the product kelp-ash. The ash, as obtained on the west coast of Scotland, contains about 18 per cent of KCl and 13 per cent of K2SO,. ? Since writing this paragraph I have been informed (April 24, 1919) by the Controller of Potash Production that most of the American kelp recovery plants have been shut down since the effective termination of the war. See also Journ. Soc. Chem. Ind. (June 15, 1919) for a recent statement of the potash position in the United States. * The World’s Supply of Potash, Imperial Institute, 1915, p. 25. Dr. A. Holmes—Non-German Sowrces of Potash. 347 collection of sun-flower stalks from the Russian peasants, and no doubt under settled conditions this source will again become productive. Cream-of-tartaris a by-product of the wine industry, and is exported in large quantities from France, Italy, and other wine-producing countries. Reference to the chief animal source of potash has already been made in connexion with saltpetre; wool, grease, and dried sweat (suint) remain for brief consideration, for this material, the waste product from processes of wool-scouring, contains the potash salts of various fatty acids. In France and Belgium K,CO, has _ been recovered from suint liquors for several years, and under war conditions its extraction was commenced in Britain. Incidentally the treatment of suint is to be advocated, if only to avoid the fouling of rivers which attends the usual method of its disposal. InsoLuBLE PorasH MINERALS. The chief silicate minerals rich in potash are felspars (orthoclase and microcline), leucite, micas, and glauconite, while a mineral which may conveniently be considered with these is alunite, a basic sulphate of potassium and aluminium. Felspars.—Although numerous attempts have been made to devise a commercially successful method of separating potash from felspar, none has yet satisfactorily emerged from the experimental stage, except possibly where the separation is introduced into, and made part of, the process of manufacturing Portland cement (see below, p- 848). In Britain! our potash-felspars are not well situated, and the cost of quarrying and carriage forbids their utilization as a source of potash, and is likely to do so unless the very bulky residue can itself be employed in a profitable capacity. Leucite.—Leucite contains about 19-5 per cent of potash, and as it is readily decomposed by acids, giving a solution of potassium and aluminium salts, it certainly provides a more favourable material for treatment than felspar. The leucitic lavas of the Italian volcanoes contain between 8 per cent (leucite-tephrite) and 10 per cent. of K,0 (leucite-phonolite), and those of the Leucite Hills in Wyoming? average 10 per cent; consequently these rocks might be treated directly, and they are undoubtedly a valuable potential asset to the countries in which they occur. H. 8. Washington? has recently drawn attention to this comparatively neglected source of potash in an elaborate review of the Italian lavas, in the course of which he estimates the reserves of potash in the seven leucitic volcanoes, extending from Vesuvius to Bolsena, at a minimum of 10,000 million tons. The corresponding American resources are but a fiftieth of this amount, and are, moreover, less favourably situated with respect to industrial centres. Already, in both areas, the rocks have been used directly as fertilizers, and the American Potash Company has 1 Mem. Geol. Sury., Spec. Reps. on Mineral Resources, vol. vy (Potash-Felspar, ete.), 1916; P. G. H. Boswell, Trans. Soc. Glass Technology, vol. ii, p. 35, 1918. 2 R. C. Wells, U.S.G.S., Prof. Pap. 98D, p. 37, 1916. 3 Met. & Chem. Eng., vol. xviii, p. 65, 1918. 3498) ) Dr vAw el olmes—Non-German Sources of Potash. been formed to extract potash from the Leucite Hills,’ but little progress has as yet been reported, while in Italy the problem is still a subject of active research. Glauconite. — British ‘‘greensands”’ rarely contain more than 4 per cent of potash, and consequently they fail to provide a practicable source. In the United States, however, potash has already been successfully recovered from glauconitic sands and marls. A narrow belt of Upper Cretaceous greensand extends from Sandy Hook to Virginia, and in many parts of New Jersey glauconite is so abundant that the air-dried sediment contains from 6 to 7 per cent of K,O, three-quarters of which can be liberated by the process adopted. Glauconite has the advantage over felspar of being practically free from alumina and soda. ‘To remove the latter impurity from potash concentrates is somewhat troublesome, and the alumina, if extracted by digestion, requires so high a proportion of water that the expense becomes prohibitive. In the case of glauconite a similar method of treatment can be applied at a comparatively low cost. ‘The process involves digesting with high- pressure steam a mixture of the finely-ground raw material with lime. The resulting filtrate contains potash with little impurity (80 per cent KOH on evaporation), while the residue contains cementitious constituents, and is utilized in the manufacture of bricks and tiles. Alunite.—Vhis mineral, the composition of which may be represented by the formula K[Al( OH), ]3(SO,)o, is readily decomposed by calcination; sulphuric acid is driven off, together with all the water, leaving a residue of soluble K,SO, and insoluble alumina. Although alunite has been generally asad) as a source of alum, in recent years high-grade potassium sulphate has been prepared from it, the first successfully operated plant having been established in Utah. Alunite occurs in veins, and disseminated through the adjacent rocks, in certain volcanic regions, where it is produced in association with propylitization, by the action of hydrothermal emanations containing sulphuric acid or its constituents. The chief localities where it is actively mined are Marysvale, Utah; Goldfield, Nevada; Bullah Delah, New South Wales; La Tolfa, Italy; and Almeira, Spain. Recovery oF PorasH From THE Dusr or Cement Kitys. Several years ago the fruit-growers in the vicinity of the Riverside Portland Cement Company, California, complained that the dust from the kilns caused serious damage to their crops. In consequence the Company took steps to abate the nuisance, and installed an electrical precipitation plant to settle the dust. Hoping that the dust might be of some economic value, and so might contribute towards the cost of its collection, analyses were made, and it was found that it contained 10 per cent of potash. Expecta- tion was thus amply fulfilled and the recovery of potash was at once developed as a profitable by-product.? 1 A. H. Rogers, Met. & Chem. Eng., vol. xv, p. 387, 1915. ’ L. Bradley, Journ. Ind. & Eng. Chem., vol. x, p. 804, 1918. Dr, A. Holmes—Non-German Sources of Potash. 349 During the last two years experimental plants have been run by certain Hritish firms for the same purpose, and although the raw materials generally contain only a very small proportion of potash, the quantities of cement manufactured are so great that a considerable output of potash is potentially available from this source. Un- fortunately, no authoritative statement has yet been issued of the results of the processes so far tested. As a further development, the scope of the experiments has recently been extended to test the suggestion that potash-felspar might advantageously be substituted in “part for the clay used as a raw material. When one part of orthoclase is intimately mixed with three parts of calcium carbonate, and the mixture heated to 1,300°-1,400° C. for about an hour, potash is volatilized, and the residual clinker corresponds in composition with that of Portland cement as normally prepared. Similarly, when the mixture is digested with steam at a pressure of from ten to fifteen atmospheres, a solution is obtained containing as hydroxide 90 per cent of the potash originally (Due sciait in the gliarec: and the residue is again a Portland cement clinker. There can be little doubt that the cement industry could, if necessary, supply very substantial quantities of potash by developing along these lines; but on the other hand the incentive of urgent national need having now passed, and the attraction of high prices being but temporary, it is unlikely that the extraction of potash from felspar by this means will become a peace industry. Brast Furnace FLur-pvust. Among the various methods exploited in Britain with a view to developing our home resources, the recovery of volatilized potash from blast-furnace flue-dust and gases has emerged as the most fruitful. Potash is present in small quantities in all the materials charged into the furnaces, iron-ore being regarded as the principal source. lIron-ores vary greatly in their potash content, the figures ranging from 0-2 to 2°5 per cent. ‘The ash from coal contains from 0-2 to 0-7 percent, but it is possible that these figures do not adequately express the potash content of the original coal, as they do not include potash that may have been volatilized during combustion. ‘That coal may possibly supply more potash than is usually recognized, is indicated by the fact that in certain experi- mental runs the potash balance-sheet actually revealed a greater recovery of potash than the amount estimated to be present in the raw materials fed into the furnace. Generally, however, the balance-sheet shows a more or less marked deficit.” Since the early part of 1915 a series of valuable experiments have been carried out by Mr. Kenneth M. Chance® of the British Cyanides Co., Ltd., and Mr. Lennox Leigh, of the North Lincolnshire Iron Co., Ltd. It was found that the volatilization of potassium as chloride could be greatly increased by adding to the charge a small 1 W. H. Ross, Journ. Ind. & Eng. Chem., vol. ix, p. 469, 1917. * BR. A. Berry & D. N. McArthur, Journ. Soc. Chem. Ind., vol. ~ooayul, Joe, Ie IE 1918. * Journ. Soc. Chem. Ind., vol. xxxvii, p. T 222, 1918. 350 Miss I. H. Lowe—Igneous Rocks of Ashprington. percentage of common salt. The conditions for successful working on a large scale have been carefully investigated, with a view to controlling the introduction of salt so that the products of volatilization should not be deleterious to the quality of the iron or to the furnace linings. The success of the experiments led to the formation of the British Potash Co., Ltd., for the commercial recovery of potash from flue-dust supplied by ‘the Wl orenaces of Lincolnshire. It is estimated that the blast-furnaces of the country should be able without difficulty to contribute at least 50,000 tons of potassium chloride per annum, an amount approximately one-half of our pre-war imports of potassium salts. ‘Thus the fear that Britain will ever again experience a shortage of potash as acute as was suffered in 1916-17 is completely dispelled. At the same time it appears to be certain that the country can never be comece ly self- supporting, unless, perhaps, the dormant exploration! of British saline deposits for potash is continued with success. IJ.—Tue Ienrous Rocks or tHE ASHPRINGTON AREA. By Miss I. H. Lower, B.Se., Demonstrator in Geology, Bedford College, a of London. . Lyrropucrion. iG South Devon the oe of Middle Devonian igneous rocks form a series of roughly parallel bands, which broaden out and occupy a continuous area about twelve square miles in extent in the neighbourhood of Ashprington village. No detailed account of the petrological characters of these rocks has been given, although similar types have been described fully in the Plymouth Survey Memoir. For this reason, and also in the hope that further study might explain more completely the cause of the broadened outcrop, I investigated many exposures in the Ashprington area. A large number of specimens were collected from this district, a general survey of which showed that the determination of the relations of the rocks to each other over any but limited areas was difficult. This was due to the isolated character of the outcrops, the comparatively rapid change in the rocks exposed, the difficulty of tracing bedding planes owing to the development of a marked cleavage, and the absence of sections showing junctions. In con- sequence a more detailed study was made of a small area east of Harbertonford village, covering about two square miles (Fig. 1) This was chosen because there were numerous exposures in a limited space, and the structure is typical of that throughout the district. The rocks examined are all basic in composition and strikingly uniform in character, and are either diabases or fragmental basic rocks. Many of the specimens collected cannot be definitely classified owing to the amount of alteration they have undergone. The absence of acid igneous rocks is very noticeable; a rotten felsitic rock from a recess in the road from Gerston Cross to Totnes was the only specimen obtained. 1 Journ. Soe. Chem. Ind., vol. xxxvii, p. R 313, 1918. Miss I. H. Lowe—Igneous Rocks of Ashprington. 351 The field work necessitated a series of visits on which Dr. Raisin accompanied me, and I should like to express my gratitude to her for the unfailing help she has given me in this work, and to Dr. H. H. Thomas, who kindly made some valuable suggestions. The work was carried on in the Geological Department of Bedford College. 2. Tue Fretp Retarions oF tHE Ienrous Rocks. A general account of the field relations of the voleanic rocks to the sedimentary in the Ashprington area is given by W. A. E. Ussher in the Geological Survey Memoir of Torquay (pp. 77 et seq.). AG | i id age EEstems! S55 SSE | Middle Middle Intrusive Diabase Coarse Finer Devonian Devonian Diabase. Lava. Tuff. Voleanic Limestone. Slates and Ash. Shales. Fic. 1.—Map showing the outcrops in the Harbertonford area. Scale, 4 inches=1 mile (approx.). The exposures! of igneous rock in the area east of Harbertonford are shown in five quarries, and form crags on the slopes of the hills * The exposures to which reference is made are marked on the accompanying map by Roman numerals. 352 Miss I. H. Lowe—Igneous Rocks of Ashprington. facing the Harbourne River. Thecontour of the ground did not seem to be dependent on the nature of the rocks, and could not be relied upon in tracing the extent of any one type. North of the River Harbourne diabase alone is exposed in onsite s Close quarry (XXII) and in several crags in a copse to the south-east (XLII). Kastward of this, in Crowdy’s quarry (XXVIII), there is a more varied section, at the base of which fine greenish-grey banded ash is shown, followed by a layer of calcareous ash containing fragments of crinoid stems and casts of brachiopods and corals, and | passing up into an impure fossiliferous limestone. Above this is an amygdaloidal lava, succeeded by ashy and concretionary calcareous bands. ‘The beds in this quarry are gently undulating, the axes of the folds running east and west. Similar sections in which ashy and calcareous bands alternate are exposed on the banks of the River Dart; from these, recognizable fossils have been obtained and are described in the Torquay Survey Memoir (p.81). To the south of the River Harbourne, in a recently opened quarry, which will be referred to as ‘‘New quarry”? (X XIX), the rock is worked from a platform about 50 feet above the level of the entrance. The section exposes at the base much cleaved fine ashy material, forming the walls of the approach to a slide down which the quarried material is shot. Above this a coarser green ash with whitish patches and silvery cleavage surfaces forms the platform, and is succeeded by a dark-green amygdaloidal diabase, which also crops out as crags on the hill above. ‘The dip of these rocks is practically horizontal. To the south, in the same hill, is a quarry (XXIV) largely overgrown, where the rock exposed is diabase, red in colour from long-continued weathering. To the south-east of Austin’s Close, forming crags in a hedge (XL, XXVII, XXVI), a rock occurs containing large fragments (9 by 4 inches and 10 by 3 inches). The fragments are splintery, subangular, and greyish-white in colour, embedded in a tough green rock. ‘The matrix showed irregular hollows on the weathered surfaces; these hollows have a distinct linear arrangement, and may represent cavities from which other fragments have been worn. The cleavage planes cross these lines and dip to the south-east at 45°; a dip which is very constant throughout the area (Fig. 2). Rocks collected from higher up on the hill (XLII, L, L1) and on the south-east slope of the hill (XXXIII-XXXVI) were not easy to distinguish as either diabase or ash. 3. PrrroLocicaL CHaRacrers oF THE Jenxrous Rocks. (1) Diabases. Throughout the Ashprington district diabase, when freshly exposed, is dark green, tough, compact, and frequently amygda- loidal. The amygdales often have a linear arrangement, are not more than an inch in length, and are filled with a fine aggregate of chlorite, sometimes associated with epidote. A few of the diabases are slate-grey in colour; the one from Down’s Hill quarry, a quarter of a mile south of Totnes, is an example of this type. It contains exceptionally large banded amygdales several inches in diameter, i} Miss I. H. Lowe—Igneous Rocks of Ashprington. 353 filled with quartz, chalcedony, calcite, and hematite. The red and brown colour of the rocks in the area is especially characteristic of those exposed in road cuttings and old disused quarries. The specific gravity of the fresher specimens varies from 2°87 to 2°98. The rocks are cleaved and generally show curved irregular joint planes; but typical ‘pillow structure”, such as that developed in the spilite in Chipley quarry and described in the Newton Abbot Memoir (p. 54), is only shown in one exposure in a small road cutting just outside Cornworthy village. A large pillow is exposed, showing numerous small vesicles arranged in concentric bands; the material of which it is formed is dark brown, but is too rotten to allow of microscopic examination. Narrow veins are abundant in all rocks, frequently intersecting and crumpled or faulted. ‘Che minerals filling the veins are quartz, epidote, chlorite, actinolite, asbestos, and calcite. Fic. 2.—Diagram illustrating the arrangements of the coarse fragments in the crag at exposure XXVII. A=imbedded fragments, B=the cavities resulting from the weathering out of the fragments. Continuous lines represent the direction of the cleavage planes. Broken lines represent the bands along which the fragments are arranged. One of the least decomposed of the diabases is that exposed in a quarry at Stancombe Linhay, two miles south of Totnes. When examined under the microscope the rock was seen to be sub-ophitic and to contain fairly large, fresh, pale puce-coloured crystals of augite, which are irregular in shape, slightly pleochroic, and are abundantly penetrated by very small lath-shaped felspars. In most of the diabases the augite is only recognizable under a } in. objective. ‘They are all noticeably rich in felspar, which must have been originally the most abundant constituent of the rock. Most rocks show two generations of felspar; those of the earlier are well- formed phenocrysts, the sections of which are elongated and rectangular or rhombic in shape. Some of the felspars show evidence of corrosion, having rounded angles, and in the rock from Down’s Hill quarry containing deyitrified glass inclusions. ‘The crystals vary in size, from microscopic to large macroscopic, one in a specimen from Austin’s Close quarry measuring 85 sq.mm. The feispars of the second generation are small and lath-shaped; in the ophitic diabases they penetrate the augite, and in the non-ophitic ty pes DECADE VI.—VOL. VI.—NO. VIII. 23 354 Miss I. H. Lowe—Igneous Rocks of Ashprington. usually have a parallel arrangement due to flow. All the felspars are much decomposed, a few still show signs of repeated twinning, the angles of symmetrical extinction of these indicate oligoclase or albite-oligoclase. The refractive index, when compared with that of the Canada balsam, is, as far as can be determined, in agreement with this identification. Skeleton crystals of ilmenite occur in the rock from Stancombe Linhay, and are also irregularly developed in other diabases. Apatite is rare, and is only present in the diabase from Down’s Hill quarry ; even in this rock it is sight in amount. All the rocks are very much decomposed ; the resulting products include chlorite, epidote, granular sphene, actinolite, white mica, and a mosaic of a clear colourless mineral, probably quartz. The chlorite occurs very abundantly in decomposed felspars, both in veins traversing the crystals and in the felspar itself; it also forms elongated irregular patches in all the rocks. Epidote is abundant in flocculent aggregates of fine granules both in the felspars and throughout the slides, and also as distinct crystals. Actinolite is present in some specimens in the form of scattered needles, in others forming a fringe from the edge of augite crystals. In one specimen the development can be seen to have taken place to such an extent that practically the whole section consists of patches of actinolite, the needles in each patch being parallel and extinguishing simultaneously. Brown hornblende is very rare, but a few small, ill-defined flakes occur in a slice of the rock collected from the old quarry south of Harbertonford. Granular sphene is associated with leucoxene as the result of the decomposition of ilmenite. Secondary iron oxide in the form of minute irregular patches can be observed in all the sections ; in much decomposed specimens earthy limonite frequently occurs as the material filling the vesicles which have been exposed to surface weathering. White mica in small flakes and a fine mosaic of a colourless mineral occur in the decomposed felspar. Kaolin as a decomposition product of felspar is especially well developed in the rock of Down’s Hill quarry. The section in this exposure showed at the east end a compact, grey, amygdaloidal rock with phenocrysts of felspar, becoming more vesicular towards the west. ‘The rock is cut by almost vertical faults, along one of which a development of kaolin occurred, forming a highly cleaved white flaky mass a few inches in thickness and stained in parts with iron. It seemed to be a final stage of decomposition of the rock, which is very rich in felspar. Calcite is conspicuously absent in these rocks, except in the cases where they overlie limestone bands, as at the old quarry near Tuckenhay. Its absence as a decomposition product of felspar gives. further support to the view that the felspar is not of a very basic species. Summary of the Decomposition of the Diabases. All the diabases of the Ashprington area are intensely altered ; the modifications which the rocks have undergone have resulted in three types of change. (1) Mineralogical alteration by which the original constituents. of the rock have been replaced by secondary minerals. Miss I. H. Lowe—Igneous Rocks of Ashprington. 355 (2) Mechanical modification which caused the breaking and deformation of the minerals and the development of cleavage planes in the rocks. (3) The disintegration of the rocks by weathering agencies. As a result of the mineralogical alteration the felspar was replaced by chlorite, epidote, muscovite, quartz, some kaolin, and possibly im some eases by calcite. These alteration products often show evidence of being developed before the rocks were modified by pressure to which this area was subjected, and probably at an early stage in their history. As a result of pressure the rocks became folded, faulted, and cleaved. The veins were crumpled, strain shadows were developed in the quartz in the veins, amygdales were elongated and flattened, and felspar and augite crystals broken. The chlorite patches also were elongated and lost any definite outline they may originally have possessed. Very little mimeral development seems to have taken place at this stage of alteration. A further effect of mechanical deformation is shown im the scoriaceous basalt from Eaglewood quarry. which is dark purple im colour and much cleaved; it passes into a purplish-red slate, with greenish and whitish patches on the cleavage surfaces. Rocks of this character are common throughout the district, and, no doubt, many of them have originated in this way, although no other exposure than the one quoted showed proof of this. The last stage of decomposition is that caused by weathering agencies which split up decomposed rocks along the cleavage planes and oxidize the irony material to minute grains of limonite and hematite, giving the characteristic red and brown colour to the soil and much decomposed rocks. (2) Fragmental Rocks. A certain number of undoubted fragmental rocks ean be identified in this area, although many of the much altered rocks cannot be definitely determined as clastic or igneous. The undoubted fragmental rocks differ in coarseness, but the recognizable fragments in all cases are mainly of felspar. In addition, some of the tuffs contain rock fragments and remains of basie lapilli- The felspars are often broken and always decomposed. Im the ease of the tuff collected from the quarry behind Crowdy’s corn mill (XXIX), the felspars could be identified as oligoclase. Aggregates of crystalline calcite are often abundant im the tuffs, and as arule - no organic structure is traceable; but im the ash from this quarry one of the calcite patches showed distinctly the typical structure of a fragment of an echinoderm. Lapilli do not oceur in the specimens collected from the main Ashprington area, but are shown in a section from a loose specimen found on a hill near Eight Acre Pens, Linhay. This is the locality referred to in the Torquay Memoir (p. 73) as occupied by a coarse voleanic tuff surrounding a probable voleanie neck. The outlines of the lapilli, which are roughly elliptical, have become very indistinct. In them the groundmass is a colourless devitrified glass, and contains 356 Miss I. H. Lowe—Igneous Rocks of Ashprington. numerous small amygdales filled with chlorite. Similar tuffs con- taining lapilli have been collected on the western borders of the area from an old quarry south of Harberton, and also from quarries east of North Huish church and south of Diptford. Rock fragments are abundant in the rock exposed in the hedge near Austin’s Close (see Fig. 2, p. 353). When examined micro- scopically they show structure characteristic of basalts, and in some, fine ophitic structure is recognizable in the groundmass. Small decomposed phenocrysts of felspar, rectangular, lath - shaped or rhombic in section are abundant, and often show a roughly parallel orientation indicative of flow. Amygdales are common, small, irregular in outline, and mostly filled with a fine quartz mosaic. Calcite patches occur, which sometimes fill the amygdales, and are sometimes associated with the decomposed felspar. One of the fragments contained two xenocrysts of felspar; their angles are rounded, and two concentric zones of mineral development occur at the margin; an outer of felspar and actinolite and an inner rich in chlorite and iron oxide granules. ‘The felspar is decomposed and contains chlorite and a few actinolite needles. A similar large felspar is found in one of the sections cut from the rock from the copse south-east of Austin’s Close. Numerous fine veins of quartz cross the rock, and patches of quartz mosaic associated with chlorite show rectangular and rhombic shape and evidently replace some of the felspar phenocrysts. The silica percentage of one of the fragments was determined as 59°6, and the specific gravity as 2°68. From these facts it is clear that, although the structure of the rock fragments is that characteristic of basalts, the silica percentage and the specific gravity are typical of less basic rocks. It seems, therefore, from the consideration of chemical composition and petro- logical characters, that the fragments are of basalts which have undergone subsequent silicification. In structure the fragments closely resemble the unsilicified rock from the copse to the south-east of Austin’s Close, from which they are possibly derived. The matrix of the tuff in which the fragments are imbedded consists mainly of broken felspar and chloritic material and an abundance of fine granular epidote. 4. Summary. The foregoing description makes it clear that the rocks of the Ashprington area closely resemble the spilites and schalsteins of Upper Devonian age in the Plymouth district, described in the Plymouth and Liskeard Memoir (p. 94 et seq. ), but the diabases of the former differ from the spilites of the latter in having fine-grained ophitic structure and in the prevalence of felspar phenoerysts. No example of coarser intrusive ophitic rock or proterobase such as is described by Dr. Flett in the Survey memoir mentioned above is met with in the Ashprington area. The sub-ophitie rock exposed at Stancombe Linhay and Eaglewood quarries approaches most closely to the ophitic type. North ‘Huish and Diptford to the west of the area (Ivybridge and Modbury Memoir, p. 78) are the nearest localities at which coarse ophitic rock is exposed. *(xoadd) opr Ass ALONG) MON MS LINXX ain sodxy Aiton) SApMozy "] OLT (OJ SV OLS OTT] ST P puU Eg ‘saliyp doy spoquids oxy 07 Loy OUT, UL =Soyoul GOT oywog “PT dVIN NI Q—@ UNIT Wi PNOTV NOIMOUG—"P VT * SU orunopoa touy ,, su poyddys oq prnoys oonyd yunyq Srey, I ” *(xorddu) opi T=soyoUur GOT o[wog *T av NI V—Y CNET WH DNOTY NOLLOWG—"g “YI —- =< ¥ - ~~ ~ aso) SUIISN Y JOTL asdo7 = Slee TIX ALN sodxT 24 {008 q aL SS a ES, at) tty te et nie | = es ASS . . ri SSN SS eae te 0 UsnOQUDHS _- => Fi ees nape watt Sais eee a MN 358 Miss I. H. Lowe—Igneous Rocks of Ashprington. The petrological characters of all the specimens of diabase collected from the exposures in the area east of Harbertonford, with the exception of that from Austin’s Close, are similar. They are fine-grained and porphyritic, showing only such variations as might be found in different parts of the same lava. Thus the rocks show more marked flow structure in some parts than in others, variation in the coarseness of the ophitic structure, and slightly different degrees of decomposition. In the exposures at ‘‘ New quarry” and Crowdy’s quarry the diabase is evidently a lava flow interbedded with ashes, and from the resemblance of the petrological characters of these rocks to those of the old quarry and of the copse south-east of Austin’s Close, it can be inferred that the last two exposures are of the same lava-flow. ‘The dip of the beds is gentle and all the outcrops of diabase occur either just above or just below the 200 feet level. The diabase of Austin’s Close differs from the other specimens. It shows no trace of original ophitic structure, and the phenocrysts of felspar are large and well-shaped, although much decomposed and with rounded angles; they have no definite arrangement. The rock seems to have been more resistant to the pressure which affected the district; cleavage is not so marked, and the felspars, though often deformed and cracked, are not so distorted and drawn out as those in more cleaved diabases. These facts suggest that this rock was not part of the same lava-flow but originated as a small intrusion shown at N.N.W. in Fig. 4. No junctions with the neighbouring rocks could be found, so that direct evidence was not available. The limited extent of the coarse fragmental rock, the size of the included fragments and their silicification, which is doubtless due to the action of vapours connected with volcanic action, leads to the conclusion that this rock occupies the position of a small parasitic vent (see Fig. 3). Similar vents were probably numerous in the Ashprington area, and if so, this would account for the extensive development of the volcanic rocks in this district. We have, therefore, near Harbertonford, evidence of a lava ‘down a great preponderance of ash, a small vent and a small intrusive mass. This is probably typical of the occurrence and origin of the spilitic volcanic rocks in the larger Ashprington area, whose develop- ment was initiated early in the Devonian period in a district that was undergoing gentle subsidence. Thus these rocks give an additional illustration of the view expressed by H. Dewey and Dr. Flett,! and more recently by Dr. A. Harker,’ as to the connection between the petrological characters of the spilites and the conditions under which they were formed. 1 GEOL. MAG., 1911, p. 246. 2 Quart. Journ. Geol. Soc., vol. Ixxiii, p. Ixkxviii, 1917. PRE AE lf Lites Grou. Maa. 1919. Prate VIII. | oe cK hewe oP ASR id eS C. D. Walcott. NEOLENUS SERRATUS (Rominger). Burgess Shale (Middle Cambrian). British Columbia. (From Walcott.) Dr. W. T, Calman—The Appendages of Trilobites. 359 IIlJ.—Dr. C. D. Watcort’s ResearcHes ON THE APPENDAGES OF TRILOBITES. By Dr. W. T. CAauMAN, D.S8c., F.Z.S., of the British Museum (Natural History). (Dr. C. D. Watcorr. Camprian Grorocy and Parronroxoey, IV, No. 4: Apprenpaces or I'R1Lopires. Smithsonian Miscellaneous Collections, vol. Ixvii, No. 4, Washington, December,- 1918, pp. 115-216 + Index, pls. xiv—xlii, text-figs. 1-3. ] (PLATE VIII AND TEXT-FIG. 1.’) T is nearly forty years since Walcott published the well-known memoir which first gave paleontologists definite information regarding the appendages of Trilobites. This work was based on a laborious investigation of Calymene senaria and some other species by means of thin sections. Since then much knowledge has been gained, and, in particular, Beecher’s researches on Zriarthrus have provided us with a new conception of the Trilobite limb which, in some respects, is not readily to be reconciled with Walcott’s earlier results. Now, at length, in this finely illustrated monograph, the veteran student of the Trilobita brings together the results of his own work and that of other investigators and reviews the whole in the light of his unrivalled experience. In all, eleven species are dealt with, and restorations are given of Calymene senaria, Triarthrus becki, and Neolenus serratus, the three species of which the structure is most fully known. The last-named species is represented by finely preserved specimens in the Burgess shale (Middle Cambrian) of British Columbia, from which Dr. Walcott has described so many novel forms of animal life in recent years. By the kindness of Dr. Walcott we are able to reproduce two of his figures illustrating Weolenus (see Plate VIII and Text-fig. 1). It will be seen from the restorations that the limbs are of some complexity. The jointed and spinous leg (endopodite) has a strong basal segment, produced inwards as a toothed gnathobase, to which are attached as many as four lobular appendages. One of these, distinguished by the marginal fringe of long sete, is identified as the exopodite, and two others, one large and one smaller, are lettered as epipodites. Another small lobe is called an ‘‘exite”’, but as it is stated to be ‘‘ probably attached to the inner side of the protopodite”’ the name is hardly well chosen. The most remarkable feature of the species, however, is the presence of a pair of long multiarticulate caudal filaments resembling those of Apus. Nothing like these has hitherto been seen in any Trilobite (Text-fig. 1, ¢.7., p. 360). In the case of Zriarthrus the modifications which Dr. Walcott finds it necessary to make on Beecher’s well-known restoration are mostly of a minor kind. The chief is the addition of a series of small leaf-like epipodites attached to the bases of the limbs. The fringes of the exopodites were described by Beecher as made up of ‘narrow, oblique, lamellar elements’’, and he suggested that they may have served as gills. ‘he photographs now given 1 The original illustrations have been kindly lent by Professor C. D. Walcott. 360 Dr. W. T. Calman—The Appendages of Trilobites. >, gm’ ey Ke NS . a LE “2 QW Se iS > S, A S 4 C2 <$ a, ‘3 sing Se le 4 SET Ratings Y) Y (pln. ear ye > os B Aaa : Y Wee Fic. 1.—WNeolenus serratus (Rominger). Restoration of the ventral aspect with appendages. Burgess Shale (Middle Cambrian), British Columbia. (From Walcott.) hy. hypostome; a.antennules ; an.anus; c.7r. caudal rami; ep. epipodite; ex. exopodite; pr. gnathobasic process of protopodite; v.27. ventral integument. Dr. W. T. Calman—The Appendages of Trilobites. 361 show some resemblance to the pectines of scorpions, and at all events the form of the elements is very different from that usually indicated by the term ‘‘setz’’ which is here applied to them. Dr. Walcott attaches considerable importance to his conclusion that the limbs of the pygidium had long and slender endopodites like those of the middle region of the body, and that the lobate, phyllopod-like elements described by Beecher should be referred to the exopodite. The photographs illustrating this point, however, are not sufficiently clear to be quite conclusive. The revised restoration of Calymene now given differs in some important details from that published in 1881. Dr. Walcott has re-examined the material on which his earlier work was done, and reproduces some of his figures alongside of photographs of the sections from which they were drawn. As now interpreted, all the limbs are provided with large gnathobases like those of Triarthrus and Neolenus. In addition to the bifid spirally coiled appendage, now called the exopodite, all the limbs bear a curiously shaped epipodite with a terminal fringe of sete. Dr. Walcott maintains his opinion thatthe two branches of the so-called exopodite were of the spirally coiled form which he originally described, rejecting the suggestion that the appearances seen in his sections resulted from the cutting across of fringes of obliquely-set lamellee like those on the exopodites of Zrzarthrus. His conclusions are not to be lightly disputed by anyone who has not studied the actual specimens, but some doubt must remain so long as these spiral appendages have only been seen in the species examined by the method of section-cutting, and not in any of the forms in which the appendages are displayed in surface view. Evidence has now been obtained that this species had filiform antennules like those of Zriarthrus and Neolenus, and they are included in the restoration. On the much-discussed question of the affinities of the Trilobites, Dr. Walcott unhesitatingly decides for their association with the Crustacea, and against the view that they were related to the Xiphosura and Arachnida. He does not discuss the reasons for this conclusion in any great detail, and it may be suggested that in the comparisons brought forward he hardly makes sufficient allowance for the very wide range of structure in the Crustacea. Thus, for example, it is only with large reserves and qualifications that the resemblances of the Trilobite limb to the thoracic legs of Anaspides can be regarded as supporting the previous comparison with Apus, while it may be stated with some confidence that the sessile eyes of Aoonunga have nothing whatever to do with the fact that the eyes of Trilobites are also sessile. Before such comparison can be profitably entered upon it is essential to have a clear conception of the classification and phylogenetic relations of the main divisions of the Crustacea, and on this point Dr. Walcott has not availed himself of the most recent information. He quotes, apparently with approval, Beecher’s arrangement of the ‘Trilobita ‘‘as a sub-class of the Crustacea, equivalent to the sub-class Entomostraca and to the third sub-class Malacostraca’’. Now it 362 Dr. W. T. Calman—The Appendages of Trilobites. is true that many writers even at the present day adopt the classification of Crustacea into the two sub-classes Entomostraca and Malacostraca, but this is due merely to the inertia of tradition. The ‘‘ Entomostraca”’ have no more claim to constitute a taxonomic unity than have the “ Invertebrata’’. The groups included under the name, the Branchiopoda, Ostracoda, Copepoda, and Cirripedia, are no more closely related to one another than any one of them is to the Malacostraca, and they should be treated as equivalent sub-classes of the Crustacea. When they are arranged in this fashion it becomes clear that the Branchiopoda are the only sub-class that can be regarded as haying any direct relationship with the Trilobites. Each of the other sub-classes has attained to a more. or less strictly defined number of trunk-somites and appendages. Only the Branchiopoda, like the Trilobita, are, to use Lankester’s term, anomomeristic. ‘The Malacostraca, in addition, have the trunk appendages grouped in the two sharply defined ‘‘tagmata ” belonging to the thorax and abdomen. The Ostracoda, Copepoda, and Cirripedia are, in different ways, highly specialized groups, and the only characters which can be usefully considered in comparing them with Trilobites are those that may be supposed to be inherited from the common stock of Crustacea. Thus, it is legitimate to supplement a comparison of the Trilobites with the Notostraca (Apus) by a reference to the more generalized mouth-parts (biramous mandible- palp, ete.) of certain Copepods. One of the pieces of evidence that has influenced opinion most strongly in favour of the Crustacean affinities of the Trilobites is afforded by Beecher’s determination of the number of cephalic appendages in Zriarthrus. Behind the preoral antennules, he found four pairs of appendages, each biramous and provided with a gnathobase. Since the antenne of Crustacea are still postoral and carry a masticatory process or gnathobase in the nauplius larva, the correspondence of the postoral cephalic appendages of Zriarthrus with antenne, mandibles, maxillule, and maxille seems to be complete. In view of the great importance of this correspondence it is much to be regretted that it has not been possible to confirm it in any of the other species of Trilobites. Dr. Walcott, indeed, repeatedly refers to four pairs of cephalic legs, but it is not clear that the precise number could be determined in any case without reference to the analogy of Zrvarthrus. The biramous form of the limbs in Zrvarthrus has been regarded, with justice, as one of the main supports of Crustacean affinity. The objection that the protopodite, to which the two rami are attached, appears to be unsegmented, while in the Crustacea it is usually composed of two, sometimes of three segments, need not’ be regarded as insurmountable. Dr. Walcott definitely describes the protopodite of the Trilobites as “consisting of a fused coxopodite and basopodite’’, but this would appear to be rather a probable inference than an observed fact. The discovery of a pair of multiarticulate caudal filaments in Neolenus is a new and weighty piece of evidence in favour of affinity with Crustacea. In one form or another a caudal furea is found in Dr. W. T, Calman—The Appendages of Trilobites. 363 all the main divisions of the Crustacean stock, and the rami are filiform and multiarticulate not only in the Notostraca (Apus, etc.) but also in certain Cirripedes. Nothing of the kind is found in any of the Arachnidan groups. While giving due weight to these and other evidences of Crustacean affinity, it is important not to lose sight of the characters, some of them of considerable weight, in which the Trilobita differ from what we must suppose the primitive Crustacean to have been like. One of the most important is the absence of a carapace. In the Crustacea the carapace is formed by a fold of the dorsal integu- ment arising from the hind margin of the head-region, enveloping and sometimes coalescing with more or fewer of the body-somites. Only in the Anostracous Branchiopoda, in some Synearida (Bathynella), and possibly in the Copepoda, is this shell-fold entirely absent, and it is a reasonable conclusion that it must have been present in the ancestral stock of the Crustacea. No Trilobite shows any trace of such a fold. The sessile eyes of the Trilobites may perhaps be reckoned as another non-Crustacean character. Sessile eyes are indeed common enough among recent Crustacea, but there are good reasons for thinking that the condition is in all cases a secondary specialization and that the eyes were primitively pedunculate and movable. Even the sessile eyes of the Notostraca and Conchostraca, which are movable and covered by an invagination of the integument, are regarded, with considerable probability, as derived from stalked eyes. In the Trilobita we have no evidence that the eyes were ever movably pedunculate, although the suggestion has been made that the eye-bearing “‘free cheeks’? may have been formed by the expansion of ocular peduncles. Finally, it is to be noted that the exopodites of Zriarthrus with their fringe of lamellar elements, possibly branchial in function, are something very different from the ‘“‘setiferous exopodites’”’ of many Crustacea with which they have been compared. It is possible that we have here a hint as to the origin of the ‘‘gill-books’”’ of Limulus. No Trilobite yet discovered is so generalized that it could be regarded as standing in the direct line of descent of either Crustacea or Arachnida, but the group as a whole seems to point the way towards some form that may have been the common ancestor of both. Dr. Walcott’s wonderful discoveries in the Burgess shale give hope of further progress in tracing the phylogeny of the primitive Arthropods, and the fuller investigation which he promises of the remarkable Marrella will be awaited with much interest. EXPLANATION OF PLATE VIII. Fic. 1.—Neolenus serratus (Rominger). Burgess Shale (Middle Cambrian), British Columbia. (From Walcott.) Specimen displaying the ventral surface with the appendages 1m sitw. At the posterior end of the body a portion of one of the caudal rami is visible. (From a retouched photograph, x14.) 5, 2.—Diagram of a transverse section of the body. d.s. dorsal shield ; ep. epipodite; ex. exopodite; ext. exite; wnt. intestinal canal ; pr. gnathobasie process of protopodite ; v.z. ventral integument. 364 H. H. Read—The Two Magmas of Strathbogie. 1V.—Tuer Two Macmas or SrraTHBoGIE AND Lower BANFFSHIRE. By H. H. ReapD, H.M. Geological Survey, Scotland. HE field-work upon which this communication is based was carried out in 1917 and 1918, in preparation for the Geological Survey map of Sheet 86 (Huntly). In the Strathbogie district of Aberdeenshire and in Lower Banffshire! two series of igneous rocks have a wide distribution. The earlier of these series was intruded prior to the movements which caused the foliation and schistosity of the Dalradian sediments, the later after these movements had ceased. The object of this paper is to detail the diversity of original rock types constituting the Older Series, to delineate their magmatic sequence, and to compare them, both in order of intrusion and in petrographic characters, with the similarly diversified Younger Series. 1. Tue Oper SERIES. Igneous rocks of prefoliation age have a wide distribution in this district, as will be seen from the Sketch-map. ‘hese Older rocks are mostly altered to serpentine, tremolitic serpentine, epidiorite, amphibolite, hornblende-schist, and augen-gneiss, but it has been found possible to trace back the serpentines to pyroxene and olivine rocks, the epidiorite, amphibolite, and hornblende-schist to gabbro and enstatite gabbro, and the augen-gneiss to granite. The most important locality of the Older Series from this point of view is that of Portsoy, Banffshire. The rocks of this locality have been described many years ago by Jameson,” Cunningham,’ and Heddle.* The non-felspathic ultrabasic members of the Older Series are usually in the condition of serpentine, occasionally well foliated but more often massive. Throughout the district, however, rocks composed wholly of monoclinic pyroxene are strongly developed and can be found in all stages of transformation to serpentinous and tremolitic derivatives. Such anchi-monomineralie rocks form independent intrusions, and since they are cut by epidiorite may be considered as the earliest manifestation of the Older igneous activity. Type localities are at Portsoy, at Whitehill west of Rothiemay Station, and on both flanks of Evron Hill. The pyroxenite is a coarse massive greenish-grey non-foliated rock which in thin slice is seen to consist of large interlocking crystal plates of a pale-coloured augite. No felspar has been seen in the rock. Occasionally olivine in small grains is scattered sporadically throughout the rock and may have been locally predominant. Enstatite and hornblende, probably primary, also occur at certain localities. There is never any banding of the constituents, collection of olivine in layers or fluxional arrangements of the * Further notes on these districts will appear in the Summary of Progress of the Geological Survey of Great Britain for 1915. ? R. Jameson, Mineralogy of the Scottish Isles, etc.,1800, vol. ii, p. 270 et seq. * Hay Cunningham, ‘‘Geognostic Account of Banffshire’’: Trans. High. and Agric. Soc. Scot., ser. 11, vol. viii, p. 447, 1842. * M. F. Heddle, ‘‘ Chapters on the Mineralogy of Scotland’’: Trans. Roy. Soc. Edin., vols. xxvii-xxix, 1876-80. H, H, Read—The Two Magmas of Strathbogie. 365 erystals. The position of such pyroxenite masses as are associated with epidiorites, etc., seems in no case due to gravitative differentiation. These pyroxenites by their alteration produce 6 MILES YOUNGER HORNFELS @ SPOTTED ROCK OLOER ANDALUSITE SCHIST YOUNGER GRANITE YOUNGEA MONZONITE, OIORITE § YOUNGER NORITE, OLIVINE GA8BRO,k TROCTOLITE & PICRITE 2\ y fee cA a Ss De te L\ ema i——\ tj) a= —z, — —=, =, =| OLOEA BASIC ROCKS, = (GABBRO, EP/OIORITE, Al AMPHIBOL/TE, ETC.) ————_————— —— oS —— \X ————— — o-5) -———— N ———_—__ OLOEA ULTAABASIC Zed ROCKS, (PYROXENITE, a SEAPENTINE, ETC.) °o rc) °o ar) oo of OLO AED SANDSTONE Hill of Tillymorgan aa Hill of ~Culsalmond Foudland — Sed eMiertcen et oe antes Sketch-map, showing distribution of Older and Younger Igneous Rocks in Strathbogie and Lower Banffshire. 366 H. H. Read—The Two Magmas of Strathbogie. a mixture of tremolite and serpentine, and in the olivine-rich types homogeneous serpentine usually results. The tremolite of the pyroxene rocks has been developed under pressure from the solid augite, the large crystals of which are crushed and distorted, the amount of tremolite present being in intimate relation to the degree of crushing suffered by the rock. At Portsoy a second independent intrusion of a monomineralic rock is furnished by a small mass of anorthosite. This coarse- grained greenish-grey rock is composed almost entirely of labradorite felspar in crushed augen between excessively fine-grained cataclastic granules of similar felspar. Scarce chlorite, rare epidote, and tale complete the rock. This anorthosite is undoubtedly an independent intrusive mass, and is against Dalradian limestone and schist on one side and a pyroxenite on the other. The great majority of Older basic rocks is derived from a gabbro which is found well preserved at Portsoy. This parent rock of the epidiorites and amphibolites is a coarse gabbro composed of labradorite, augite, apatite, and iron oxides, with secondary hornblende and biotite. ‘lhe rather elongated crystals of labradorite are saussuritized and slightly crushed. ‘he ophitic augite is marginally altered to the fibrous or compact hornblende of the epidiorites. Primary modifications of this gabbro are common, but form only local variations in the gabbro mass. By the dwindling of the felspar content and by the incoming of olivine, a rock is formed in which the original constituents were olivine, diallage, and scarce labradorite. The olivine, now entirely replaced by pilitic tremolite, quartz, chalcedony, and carbonates, formed rounded grains poikilitic in large diallage plates which are in process of alteration to hornblende and biotite. The felspar is a scarce rather fresh basic plagioclase. Compound reaction rims between the olivine and felspar are occasionally developed and are exactly similar to those found in certain types of the Younger Series. ‘The rock is occasionally crushed. In the Burn of Durn at Portsoy an enstatite gabbro is found in which a colourless enstatite is predominant over the monoclinic pyroxene. Both species of pyroxene are partially or completely altered to a pale-green hornblende, and cataclastic effects are common in the plagioclases. Bands and streaks of a rock more acid than the predominant type are found in the gabbro of Portsoy. Such dioritic types are composed of a medium plagioclase, quartz, and biotite. Primary banding is common in the Portsoy gabbro. This is of two types, the first being formed by alternations of two rocks, the second by alternations of two minerals. The first type consists of bands of a labradorite rock with a little hornblende secondary from pyroxene, alternating with bands of hornblendic (originally pyroxenic) rock with subordinate plagioclase. This complementary banding is undoubtedly original. Those rocks to which the name | gabbro schist may be applied show a delicate banding of light coloured saussuritized labradorite and of dark secondary hornblende enclosing augen of diallage. This banding is due to movement. H. H. Read—The Two Magmas of Strathbogie. 367 during consolidation, and the effect of the subsequent cataclasis has been to emphasize the banded nature of the rock, which in structure then resembles the foliated gabbro described and figured by Teall.! All banding is parallel to the stress lines of the country. The olivine-pyroxene-felspar rock, enstatite-gabbro, diorite, and banded gabbros do not form independent intrusions, but are small parts of a heterogeneous intrusion whose predominant member is ordinary gabbro. No differentiation in place can be demonstrated and it is considered that this heterogeneity is due to differentiation before intrusion. All the varieties of the gabbro pass into epidiorites by the complete replacement of their pyroxene by secondary horn- blende. From the epidiorites are derived the widespread amphi- bolites by a still more abundant development of secondary hornblende and the concomitant recrystallization of the original labradorite into a mosaic of clear acid plagioclase. ‘These two types, displaying no marked foliation, are predominant in the Older basic series as now found. By the development of cataclastic foliation the horn- blende-schists are produced. The acid members of the Older Series are exemplified by the augen-gneisses of Portsoy and Windyhills. In these rocks large lens-shaped patches of microcline and orthoclase, with subordinate oligoclase, are set in a cataclastic groundmass of granular quartz and felspar with shreds of primary biotite, and much secondary muscovite along shear planes. ‘The original rock was a biotite microcline granite. The magmatic sequence of the Older Series is, as usual, one of decreasing basicity or of increasing alkalinity. The main magma was largely gabbroic in nature and has been intruded as a hetero- geneous magma due to differentiation in a lower basin, and now displays the varied types of predominant gabbro, scarce olivine- pyroxene-felspar rock, scarce enstatite-gabbro, scarce diorite, with banded felspathic and pyroxenic portions. The manner of differentiation cannot be stated, but no degree of differentiation in situ has taken place. The anchi-monomineralic rocks are earlier than the gabbro; one of these independent intrusions is composed of the femic constituents, the other of the felspathic constituent of the original gabbroic magma from which they have split. The acid differentiate is quite late and consists of an alkali-granite. ‘The areal relations for this district of the three divisions are ultrabasic rocks 2°6 square miles, basic 15:6 square miles, and acid 1°55 square miles. The basic rocks are much cut out by the Younger Series, and the area formerly occupied by them may be approximately double that given above. The Older Series must be considered with regard to Dr. N. L. Bowen’s” recent work on differentiation by the sorting and collection of crystals in a crystallizing magma. At Portsoy among the Older 1 J. J. H. Teall, Gkou. MaG., 1886, Pl. XIII,p. 481; British Petrography, 1888, pls. xxvi, xliii. 2 N. L. Bowen, ‘‘ The Last Stages in the Evolution of the Igneous Rocks ’”’: Journal of Geology, vol. xxiii, supplement, pp. 1-91, 1915. ‘*‘ The Problem of the Anorthosites’’: ibid., vol. xxv, p. 209, 1917. > 368 H. H. Read—The Two Magmas of Strathbogre. Series, and as will be seen later at Huntly among the Younger Series, it can be shown that differentiation has not taken place in situ. he absence of gravitative separation and of continuous variation and the presence of independent monomineralic intrusions point to the conclusion that differentiation took place in a lower magma basin. The main intrusion was undoubtedly one of a heterogeneous,! predominantly gabbroic, magma, and from this magma had already been separated off the two monomineralic types —pyroxenite and anorthosite. On Bowen’s theory, such separation of monomineralic types would be by the collection of masses of erystals of pyroxene and of labradorite, and therefore, if such monomineralic rocks were intruded as independent masses, their origin would be demonstrated by cataclastic structures. Such structures are, of course, apparent in the monomineralic rocks of Portsoy, but these rocks were affected by the regional folding and, in common with all the igneous rocks of the Older Series, show evidences of crushing stresses. How, then, are these crush effects due to later folding to be distinguished from those due to intrusion as amass of crystals? Orientation of crystal plates has never been seen in the massive pyroxenites of this series, there is no segregation of olivine into layers, and the crystals of pyroxene form interlocking junctions. ‘he sporadic olivine is often interstitial to the pyroxene. In the author’s opinion, the crushing seen in the pyroxenite is best explained as due to the effects of regional folding on a solid and cold rock. Similarly the crushing of the anorthusite is exactly like that of the augen-gneisses. Until further knowledge is obtainable concerning the immiscibility of silicate magmas,’ especially under pressure, and also concerning the role of mineralizers, particularly of magmatic water, in ultrabasic rocks, the question of the origin of the monomineralic rocks of the Older Series must be left open. On the whole, however, the writer considers some kind of separation of a magma into liquid phases to be demanded by the field relations of the Older Series of this district. Such a separation of liquid phases would be afforded by the operation of liquid immiscibility, or by the refusion of a solidified magma basin already differentiated, perhaps by crystallization. Such a refusion was postulated by Martin Schweig* and has lately been favoured by Dr. Harker,* but the cause of the rise in the isogeotherms evoked by the latter is unexplained. Liquid immiscibility, therefore, until proved impossible, should be considered as a process probably effective in magmatic differentiation. 2. THe Youncer SERIES. The Younger Series of the Strathbogie district forms an elongated mass with a north and south trend, a direction parallel to the 1 Cf. Geikie & Teall, ‘‘ On the Banded Nature of some Tertiary Gabbros in the Isle of Skye’’: Q.J.G.S., vol. 1, p. 656, 1894. 2 Cf. R. A. Daly, Igneous Rocks and their Origin, 1914, pp. 225, 226. ‘‘ Genesis of Alkaline Rocks’’: Journ. Geol., vol. xxvi, pp. 123, 124, 1918. 3M. Schweig, ‘‘ Untersuchungen tiber Differentiation der Magmen’’ : Neues Jahrbuch, Beil. Bd. xvii, p. 563, 1903. 4 A. Harker, ‘‘ Differentiation in Intercrustal Magma Basins’’: Jowrn. Geol., vol. xxiv, p. 556, 1916. S H. H. Read—The Two Magmas of Strathbogie. 369 foliation of the country. The younger igneous rocks of the Wardhouse district will not be considered here. That part of the Huntly Mass which occupies the district around Huntly has been described in detail by W. R. Watt,’ but the whole of the area shown in the Sketch-map has been mapped by the present writer. The rocks of the Huntly Mass, with its isolated granite bosses of Aberchirder, Ord, and Longmanhill (4 miles E.S.E. of Banff), form a lengthy sequence, here appended in order of intrusion: — 1. Picrite-Norite Set(Picrite, Olivine-gabbro, Troctolite, Norite). 2. Diorite of Gibstone. 3. Monzonite and Diorite (Central Intrusion of W. R. Watt). 4, Granite. 5. Pegmatites with tourmaline. The picrite-norite set are well seen around Huntly and extend thence northwards to within two miles of Portsoy. The picrite forms a narrow border on the western edge of the Huntly Mass in the Huntly district. It is a black rock with conspicuous lustre mottling and in thin slice is rather variable. Occasionally it approximates to a peridotite, but usually carries common ophitic pyroxene with relatively scarce basic plagioclase. Brown horn- blende, biotite, and hypersthene occur in smallamount. ‘The olivines are slightly serpentinized. No trace of cataclastic structure is found. The olivine-gabbro occurs east of the picrite and forms a coarse very fresh rock with labradorite, olivine,and pyroxene, with sub- ordinate brown hornblende and biotite. ‘The troctolitic type occurs mainly east of the olivine gabbro and is a characteristic olivine- labradorite rock with beautiful fluxional arrangements of the felspars and with banding of more basic types of peridotite, etc. These fluxion structures are parallel to the margin of the mass, as is usual amongst fluxional gabbros.?, Such structures are best explained for the Huntly Mass as due to movement during the intrusion of a some- what pasty and not strictly homogeneous magma. Troctolite also occurs at the western edge of the Huntly Mass west of Knock Station. Beautiful reaction rims of anthophyllite and actinolite are developed between the olivine and felspar of the troctolitic and olivine gabbros.? The predominant body of the picrite-norite set is, however, the norite. This type forms nine-tenths of the Huntly Mass. It is usually a fine-grained bluish rock, consisting of labradorite-bytownite and hypersthene with widespread augite, hornblende, biotite, and olivine. Structures are variable, being ophitic, granular, or granitic. Occasionally the norite lacks its hypersthene and then forms a very coarse gabbro. The members of the series—picrite, olivine-gabbro, troctolite, norite—follow in order from west to east, and at first glance this arrangement seems to point to a direct gravitative differentiation of a gabbro magma in the position in which it is now found. But no 'W. R. Watt, ‘‘ Geology of District around Huntly (Aberdeenshire) ’’ : Q.J.G.S., vol. lxx, pp. 266-93, 1914. 2 F. F. Grout, ‘‘ Internal Structures of Igneous Rocks’’: Jowrn. Geol., vol. xxvi, p. 439, 1918. 3 W. R. Watt, loc. cit., pl. xxxviii, fig. 2. DECADE VI.—VOL. VI.—NO. VIII. ; 24 370 H. H. Read—The Two Magmas of Strathbogie. gradual passage from one rock to another can be demonstrated and the individual rock types are well marked. Again, the west—east. sequence in certain localities may be partly reversed. Moreover, there is no ultrabasic western border to the norite north of the Huntly district. It seems more probable that the differentiation of a gabbroic magma took place in a lower chamber and that the picrite was intruded as a small sill, followed by increasingly acid derivatives, each of which slid in roughly on the top of its fore- runner. But most of the picrite-norite set were fluid at the time of intrusion of the whole series and so no marked contacts are seen; schlieren and banded types occur and mixed edges may have been formed locally. Finally, the phase of the picrite-norite set was ended by the widened sphere of sill-like intrusion, together with great cross-cutting, of the norite magma, and by the time of intrusion of this norite the more basic members were sufficiently solid to be cut by dyke-like apophyses of gabbro and norite. The areal relations of this set are: picrite °83 sq. mile, olivine-gabbro 39 sq. mile, troctolite 3°32 sq. miles, and norite 37:4 sq. miles. After the composite intrusion of the picrite-norite set had finished, there were intruded a few smail bosses of diorite (quartz, biotite, augite, andesine). Of these bosses, that at Gibstone (14 miles N.W.. of Huntly) has a marked foliation which is, however, not of cataclastic origin. ‘This Gibstone diorite is intermediate in composi- tion between the earlier norite and the later monzonite, and probably owes its foliation to its soft and hot nature at the time of the move- ments which caused the monzonite to present a markedly intrusive character to the norite. The picrite-norite set was solid at the time of intrusion of the large monzonite mass of the Bin Wood (Central Intrusion of Watt’). This rock is a coarse garnetiferous monzonite which has produced great contact effects on the earlier norite.? It consists of orthoclase, plagioclase, augite, biotite, quartz, and garnet. The next member of the Younger Series is of granitic nature and forms small masses, sometimes in the basic members and sometimes. as isolated bosses, as shown on the Sketch-map. ‘he rock is a grey granite composed of quartz, predominant microcline, orthoclase,. scarce plagioclase, biotite, and scarce muscovite. It often shows a very rude fluxional structure. All the granites associated with the Huntly Mass are biotite-microcline granites. Tourmaline pegmatites are common as the final stage in the intrusion of the Younger Series of the Huntly Mass. The areal distribution of the whole Younger Series of this area is: ultrabasic °83 sq. mile, basic 41 sq. miles, intermediate 2°8 sq. miles, and acid rocks 3:2 sq. miles. Continuous variation in place is not seen in the Huntly Mass, and there seems to be an individuality about the various closely related types which is not explained by a crystallization-differentiation hypothesis. 1 W. R. Watt, loc. cit., p. 275. 2 W. R. Watt, loc. cit., pp. 282 ff. Dr. J. Allan Thomson—Brachiopod Nomenclature. 371 3. Tue Two Series. On comparing the two series of igneous rocks outlined above, it will be seen that there is a well-marked similarity in sequence and characters, but this similarity does not extend to details. ‘he Older Series forms two anchi-monomineralic differentiates, one a femic type consisting of predominant pyroxene with subordinate olivine, the other of a felspathic type provided by the small anorthosite of Portsoy. The Younger Series has only a locally developed monomineralic phase, and its ultrabasic member is provided by a predominant olivine type with subordinant pyroxene and plagioclase, intrusion occurring before the production of a non- felspathic femic magma had been possible. So, felspar is common in the picrite of this series, but is never found in the pyroxene-olivine rocks of the Older Series. The basic members of the two series again present the same general types of gabbro, enstatite or hypersthene-gabbro, and diorite, but are different in the relative development of such types, in the predominance of certain species of pyroxene, and in the widespread occurrence of olivine in the Younger Series. The acid members are perfectly similar, both being biotite-microcline granites. ‘The areal relations of the Older Series and of the Younger Series of the Huntly Mass show the same order of magnitude for the different differentiates of each series. The distinction between the two series may be based upon the degree of alteration of the rocks, the character of this alteration among the Older Series, the characters of the predominant mineral in the ultrabasic facies, and the character of the pyroxenes in the two orthorhombic -pyroxene-gabbros. In the field, the general greenish appearance due to the alteration into hornblende of the augite of the Older Series and the occurrence sooner or later of eataclastic foliation in them are of great value. Finally, a most important criterion is supplied by their metamorphic effects on the country rocks. The contact rocks produced by the Older Series are foliated by the later regional folding, whereas the effect of the intrusion of the Younger Series is to obliterate this foliation. It may be stated, therefore, that in this district there are two petrogenic cycles separated by an epoch of great earth movement. Between Huntly and Portsoy the rocks of these two cycles have risen along almost the same belt of country and present great similarities in their main characteristics. In conclusion, the author wishes to express his indebtedness to Dr. John Horne, F.R.S., and to Dr. J. S. Flett, F.R.S., for many helpful suggestions. V.—Bracuiorop NomencrarurE: Spirmrer and SYRINGOTHYRIS. By J. ALLAN THOMSON, M.A., D.Sc., F.G.S., Director of the Dominion , Museum, Wellington, New Zealand. CCORDING to a strict interpretation of the international rules of zoological nomenclature the generic name Spirifer is wrongly used for the group including Anomuites striatus, Martin, and should be restricted to the group including Anomites cuspidatus, Martin, 372 Dr. J. Allan Thomson—Brachiopod Nomenclature. i.e.it should replace Syringothyris, Winchell. My object in pointing this out is not to urge a strict interpretation of the international rules in this case, for it would serve no useful purpose to attempt to displace a name which through a century of usage has become the geological equivalent of a household word, but to show the need for geologists to combine with zoologists in demanding a list of nomina _ conservanda in zoology. In 1814 or 1815 James Sowerby read a paper before the Linnean Society describing the presence of spiral coils in Anomites striatus, Martin, and proposing for it the genus Spirzfer. He also stated that he suspected that Anomites cuspidatus, Martin, possessed similar coils. The substance of this paper became known not only in England but on the Continent, but the paper was not published until 1821.’ In the meantime Sowerby published the genus in Mineral Conchology, vol. ii, 1818, pp. 41-48, Tab. 120, giving a diagnosis of the genus, followed by a description of Spirrifer cuspidatus. Other species are mentioned, but none are named. King, Meek, and others have accepted Anomites cuspidatus as the type of Spirifer, but Davidson urged that Sowerby’s intention that Anomites striatus should be the type must be accepted, and in this he has been followed by most subsequent authors, and Anomites cuspidatus has since been referred to the genus Syringothyris, Winchell, 1863. It Anomites cuspidatus is regarded as the type of Spirvfer, Syringothyris becomes a synonym of Spirifer, while the group of Anomites striatus must take another name. Dall? sums up the position thus: If the work of restriction were to be done over again, it is probable that most authors would consider the rules of nomenclature better served by taking cuspidatus as the type, but the reverse process has been the rule among authors so long that it would be a serious detriment to science to attempt such a change at present. Since the Fourth International Zoological Congress at Cambridge in 1898 there has been a Permanent International Commission on Zoological Nomenclature which studies questions of nomenclature and renders opinions upon cases submitted to it. Opinion 30° on Swainson’s Bird Genera of 1827 almost exactly applies to the case of Spirifer. Swainson wrote and sent for publication to the Zoological Journal a paper containing diagnoses of several genera, with explicit designation of their types. This first written paper ' was unexpectedly long delayed in publication, greatly to the disappointment of the author, as he stated, who was powerless to prevent the inopportune delay. This paper was published in two 1 Fide W.H. Dall, ‘‘ Index to the Names which have been applied to the Subdivisions of the Class Brachiopoda’’: Bull. U.S. Mus., No. 8, 1877, p. 63. F. J. North (‘‘ On the Genus Syringothyris, Winchell’’: GEOL. MAG., Dec. V, Vol. X, pp. 393-401, 1913) gives the date of publication as 1818. I have not access to the publication in question, but all authors agree that it was published subsequently to Min. Conch., vol. ii. ? Loe. cit. * “Opinions rendered by the International Commission on Zoological Nomenclature.’’ Opinions 30-7. SmithsonianIn stitution, Publication 2013, 1911, pp. 69-72. i Dr. J. Allan Thomson—Brachiopod Nomenclature. 878 parts appearing April—July, 1827, and August-November, 1827. In the meantime he described some new species of Mexican birds in a paper which appeared in the Philosophical Magazine in May and June, 1827, referring some of them to the new genera proposed in the earlier written but later published paper. The International Commission held that Swainson’s bird genera in the Philosophical Magazine of 1827 are monotypic, and according to Article 30 (c) the species mentioned are types of their respective genera. Therefore, these types must take precedence over the designated types of Swainson which occurred later in the Zoological Journal of 1827. The argument on which this opinion was based was stated as follows :— ‘* Tn order to fully realize the bearing of the principle involved in the present case, let us ask ourselves the question: What was the type of these genera in the interim between the prior publication in the Philosophical Magazine and the type designation in the Zoological Journal? During these ‘two or five months (as the case may be)’ the genera rested solely on the generic name and the single species described in the Philosophical Magazine. No other species was known to belong to these genera during the two or five months. Surely during that period these generic names were monotypic, and could rightfully have no other type than the only species then described. But if a genus once has a rightful type there is no way under the international rules to substitute another later. If a genus has been monotypic for two or five months, or any other length of time, subsequent publication cannot alter its status however plausible may be the argument otherwise, and this status can be no more ‘subject to change’ than ‘ designation of the type’ itself. *“ Any interpretation other than the one here followed might give rise to serious complications. For instance, to admit that a later article can undo the types actually (though possibly unintentionally) published in an earlier article, as in this case, would make it possible for an author to publish a genus as monotypic and then, years later, to alter his type in some manuscript the publication of which had been purposely or unintentionally delayed for decades. Thus, unless an author definitely stated that a genus was monotypic, no genus originally published with mention of only one species could be looked upon as having the genotype definitely established until after the author’s death, and after it was proved that he left no unpublished manuscript behind him.” The case of Spirifer is extremely similar but simpler. From 1818 to 1821 the genus was monotypic so far as Sowerby was concerned, and included only Spirifer cuspidatus, and this, therefore, cannot be displaced as the type of the genus if the international rules are to be adhered to. Thanks to Punch, the name Jchthyosaurus has become a household word in a more complete sense than Spirzfer, but it also can be used only in contravention of the international rules. It was proposed by Conybeare in 1821, but it is preoccupied by Proteosaurus, Home, 1819. Lydekker' stated the case thus: ‘‘There is no real 1 R. Lydekker, Cat. Foss. Rept. Brit. Mus., pt. ii, 1881, p. vii. 374 Reviews—WNovitates Palwozoice. justification for superseding the earlier name Protecosaurus by the later Ichthyosaurus; but since the latter name has been universally adopted, the writer, after consultation with the Director of the (British) Museum, has come to the conclusion that this is one of the cases where an adherence to the rule of priority is not advisable.” An analogous case is furnished by the common molluse, popularly known as Octopus. Asa matter of fact Octopus, Lamark, 1798, is preceded by Polypus, Schneider, 1784, and in this case malacologists have applied the rule of priority and displaced Octopus,’ but it may be doubted whether the interests of science are best served by such action. These three cases, and doubtless many others which could be cited, show that a rigid application of the law of priority will displace names which by a century of usage have found their way - into hundreds of textbooks, and even into popular literature. The best way to avoid so regrettable a* step is for an International Zoological Congress to adopt a list of nomina conservanda. This paper is written to enlist the co-operation of geologists in creating a public opinion in this direction. RHEVLAEwWwWsS. I.—Novirares PaLmozoica. PaLEonToLogic Conrrisutions From THE New York Strate Museum. By Ruporr Rurpemann. N.Y. State Mus. Bulletin, No. 189. 226 pp., 36 pls. September, 1916. HE belated appearance of this review must be excused by the War’s delays, which hindered the receipt of the volume. It would, however, be a pity to pass over for that reason all the observations of interest that Dr. Ruedemann has here collected. Let us consider a few of them. Plumalina piumaria, from sandy shales of the Portage group, described by J. Hall as a graptolite and referred by J. W. Dawson to the plant Lycopodites, is here said to possess no thece, but to have an inner solid carbonaceous (? chitinoid) axis and an outer granular (? calcareous) rind, comparable with the structure in the Gorgonide. The fossils are therefore referred provisionally to the Alcyonaria. Another plant-like fossil, Buthotrephis lesquereuxi, from the Silurian EKurypterus beds, is found to consist of twisted thin tubes opening on the general surface in pores (about *d to 1 mm. linear), and is referred to Inocaulis, which Dr. Ruedemann regards as a graptolite allied to Dictyonema. Some species hitherto referred to Dictyonema (D. fureiferum Rued., D. cervicorne et alia Wiman) are shown to have apertural processes with forked ends which attach themselves to the neighbouring branch, and so, while outwardly resembling the dissepiments of Dictyonema, differ from them in origin; they are placed in a new genus Airograptus, which should have been spelled 1 e.g. H. Suter, Manual of the New Zealand Mollusca, Wellington, 1913, p. 1062. Reviews—Novitates Pulcwozoice. 315 Haerograptus. Dr. Ruedemann has previously described colonial stocks of various genera, but not of Climacograptus; he now figures a fine example of one in C. parvus. The strangest fossil of the Portage beds was described in 1900 by Dr. J. M, Clarke under the name Cr yptophya and referred by him to the echinoderms. ‘Th. Fuchs (1905) suggested that it was the float of a siphonophore, and this view is strengthened by the recent discovery of specimens in which presumed air-chambers have been injected with sediment. A curious imprint from the same beds, on which a new genus Plectodiscus is here based, is probably a related form. From the Glens Falls Limestone at the base of the Trenton, Dr. Ruedemann has obtained a Pleurocystis, the first found. in New York State, and figures it as ‘‘ Plewrocystites squamosus (Billings) mut. matutina nov.’’? Why should Billings be in brackets, by the way? In the absence of a detailed description and measurements, one cannot say more than this: the fossils are certainly specifically distinct from P. squamosa, but closely resemble the Kentucky fossil P. mercerensis Miller & Gurley (not mentioned by Dr. Ruedemann) in all the characters that I have regarded as ‘‘ specific’? for this genus, as well as in the radiate sculpturing of the plates, a somewhat unusual feature. (See Trans. R. Soc. Edinburgh, 1913.) The many valuable notes on Devonian Asteroidea, with their beautiful illustrations, may be left for Dr. W. K. Spencer to deal with. Here let us only state that they propose the new genera Clarkeaster, Lepidasterina, and Klasmura. ‘There are also two new starfishes from the Silurian Conularia Limestones of Argentina, one an nerinaster, the other serving as basis for a new genus, Argentinaster. A curved, flattened, segmented body from the Marcellus shale, with overlapping scales on the concave margin, is certainly, as Dr. Ruedemann says, reminiscent of certain paleozoic fossils usually referred to the Cirripedia. He prefers, however, to regard it as a new species of Protonympha J. M. Clarke, which may be a polychztous annelid. Several annelid tubes from paleozoic rocks, apparently congeneric with Serpulites longissimus Murchison, are shown to spring from the adhesion discs which J. Hall described as Sphenothallus under the impression that they were plants. These fossils also present close resemblance to Zoredlella Holm, and a further link with the Conularida is thought to appear in Conularia gracilis Hall. Dr. Ruedemann therefore suggests that the Conularida may be derived from the Annelida. The description of some new species of Spathiocuris revives the discussion about the Discinocarina. H. Woodward has considered them to be crustacean carapaces. Roemer and others took them for aptychi of goniatites. J. M. Clarke hesitates between a brachiopod, crustacean, and cephalopod connexion. Dr. Ruedemann now brings further ar uments in support of their aptychus nature, though without fully satistying even himself. In some specimens of Lower Silurian age, Dr. Ruedemann recognizes the first American representatives of the doubtful fossils 376 Reviews—WNovitates Palwozoice. which Barrande called Anatifopsis, and their study leads him to conclude that the genus should be placed in the Lepidocoleide. His description and figures are, however, far from convincing. For one thing, the ornament of his fossils differs in several respects from the growth-lines of both Anatifopsis and Lepidocoleus. The description of some new LEurypterid remains leads Dr. Ruedemann to traverse the view of A. W. Grabau and Miss M. O’Connell that the Eurypterids always lived in rivers, and this he does to good effect. The existence of eyes in the limuloid arachnid Pseudoniscus, of Silurian age, has long been debated. Specimens of two species here described show small but distinct eyes on the facial suture further forward than they had been alleged to occur in the known species from Oesel. Somewhat similar reduced eyes in the trilobites have occasionally been called ‘‘ ocelli’’, but no eyes truly homologous with the ocelli or median eyes of Merostomata and of various Crustacea have hitherto been demonstrated. Both Beecher and Cowper Reed, however, have suggested that the distinct and isolated tubercle on the median line of the glabella in Zrinuclews may be such a median eye. Dr. Ruedemann now maintains the correctness of that suggestion, and extends it to most, if not all, trilobites, for the following reasons. Such a tubercle is found in many species belonging to over thirty genera, and its frequent association with a smooth glabella proves that it had some use. In 7. tesselatus, of which he gives good figures, and in other species, he has found evidence of a lens, not crystalline, but probably a sack filled with fluid. The test is thinner over the tubercle. The tubercle is more prominent in early growth-stages, as are true ocelli, and is well developed when the lateral eyes are aborted. It is always on the highest point of the glabella, generally between the lateral eyes, and often at the hinder end of a short crest which may indicate the course of the nerve. An ocellar tubercle or mound is commonest in Ordovician and Silurian trilobites. In Cambrian genera there is some evidence of transparent:spots. In Devonian genera the strong development of the lateral eyes may have led to the loss of the median eye. The occurrence of a median eye in many primitive arthropods renders it @ prior’ probable that such an organ was also possessed by the trilobites. The discovery of a median eye in Zrinucleus showed that the vestigial eyes of that genus were not ocelli but lateral eyes, and suggested search for the sutures on which they should occur. The detection of these here and elsewhere corroborates the views of Jaekel, Richter, and Swinnerton (Gror. Mae., 1915, p. 490) and upsets the Order Hypoparia. The search also led to the discovery of a new suture, which starts from a minute tubercle at the front end of the short crest mentioned above, and diverges to enclose the middle region of the front end of the glabella. Dr. Ruedemann suggests that this is ‘“‘the rostral piece or epistoma . . . drawn up into the glabella by the exceptional swelling of the frontal lobe of the glabella and the development of the broad brim’’. Enough has now been said to show how the paleontologists of Reviews— Mesozoic Insects of Queensland. 377 New York State are still making us their debtors, and to warrant our once more exclaiming with Miranda: O wonder! How many goodly creatures are there here! O brave New World, that has such people in’t! F, A. Baruer. II.—Mesozorc Insecrs or Quepnsranp. By KR. J. Trryarp. (1) Planipennia, Trichoptera, and the new Order Protomecoptera ; (2) The Fossil Dragon Fly Aschnidiopsis flindersiensis (Wood- ward) from the Rolling Downs (Cretaceous) Series; (3) Odonata and Protodonata; (4) Hemiptera Heteroptera; the Family Dunstaniide. Proc. Linn. Soe. N.S. Wales, xlii, pp. 175-200 (1917), 676-92 (1918); xliii, pp. 417-36, 568-92 (1918). FJVHE first, third, and fourth of these papers deal with the insects of the Ipswich Beds (Upper Trias) of Ipswich, Queensland. It is stated to be a definitely Mesozoic fauna, not unlike that of the Lias of England, but including a number of older forms apparently relics of the Coal-measure fauna; it is especially interesting because it fills up a gap in the succession of insect faunas owing to the hiatus in the Trias of the Northern Hemisphere. Protopsychopsis 1s a new genus of the Order Neuroptera Planipennia; Mesopsyche and Triassopsyche are new genera of the Trichoptera. The new Order Protomecoptera, including Archipanorpa, n.gen., forms a connecting link between the Paleozoic Paleodictyoptera and the recent Mecoptera. New genera of Odonata are 7Zriassolestes and Perisso- phiebia. Aéroplana, n.gen., of which the venation does not show any close relationship to that of any other insect, either fossil or recent, is referred to a new sub-order (Aeroplanoptera) of the Protodonata. The affinities of Dunstania are discussed at considerable length; it was formerly regarded by the author as belonging to the Lepidoptera, but is now referred to the Hemiptera Heteroptera. ‘lwo new genera (Dunstaniopsis and Paradunstania), allied to Dunstania, are described. The second paper deals with a dragon-fly from the Rolling Downs Series (Cretaceous) of Flinders River, North Queensland. This was originally described by Dr. H. Woodward (1884), who recognized its relationship to Aschnidium from the Purbeck Beds of Dorset. ‘This specimen is described in detail by Dr. Tillyard, who regards it as the type of a new genus, schnidiopsis. IJJ.—Permian anp Triassic Insecrs rrom New SourH WaALtEs, IN THE Cottecticn or Mr. Jonn Mitcuetn. By R. J. Trutyarp. Proc. Linn. Soc. N.S. Wales, vol. xlii, pp. 720-56, 1918. fJ\HE Permian insects described in this paper come from the upper part of the Newcastle Coal-measures, which are generally classed as Permo-Carboniferous on account of the affinities of the marine fauna. The insects are associated with a Glossopteris flora, and have nothing in common with any known Carboniferous fauna, but show distinct affinities with Triassic forms. New genera of the Hemiptera Homoptera are Permoscarta and Permofulgor, the latter believed to have close affinity with the ancestors of the recent Fulgoride. The 378 Reviews—Iron Ores of Scandinavia. Mecoptera are represented by Permochorista, n.gen., from which it appears that the Mecoptera are probably the most ancient of all Holometabolous insects. The Triassic insects come from the Wianamatta Shale Beds at horizons from 300 to 700 feet above the Hawkesbury Sandstone, and are regarded as of Upper Triassic (probably Keuper) age. Voto- blattites was originally placed in the Blattoidea, but is now referred to the Protorthoptera, and it is suggested that the cockroaches do not really belong to a separate Order, but are a specialization from a very ancient Protorthopteroustype. J/esopanorpa, n.gen., isreferred to the Mecoptera. The Coleoptera are represented by Ademosyne, Elateridium, Adelidium, n.gen., and Metrorhynchites; the Hemiptera Homoptera by Zriassopsylla, n.gen. IV.—Iron Ores oF ScAaNDINAVIA. JERNMALM 06 JeRNVERK. ByJ.H.1L. Voar. Norges Geol. Undersok, No. 85, pp. 181, with 4 figs. Kristiania, 1918. \HIS important memoir of the Norwegian Geological Survey consists of two parts; the first part includes a review of the iron-ore production of Norway in recent years and especially since the publication of the author’s earlier work, Vorges Jernmalm- Jorekomster (1910), together with statistics of export, import, and consumption of iron, import of coal and coke, and prices of ore and of pig-iron. It isinteresting to find that in 1915 Sydvaranger produced, by magnetic concentration, 600,000 tons of 65 per cent ore, of which nearly half was briquetted; this ore contains no titanium, chromium, or vanadium, while phosphorus and sulphur amount to only 0°012 percent in the concentrates; the production is expected shortly to reach 900,000 tons per annum. But of the 32 million tons of iron- ore shipped from Norwegian ports in 19138, 34 million tons were Swedish ore, mainly from Kirunavaara, exported via Narvik. About eighty pages are occupied by a full and detailed account of the mining districts of Arendal, Kragerd, Nissedal, Nordmore, Trondhjem Fjord, Tromso, and Sydvaranger, as well as the less important occurrences of Bogen and Dunderlandsdal. Owing to its importance to Norwegian export trade and commerce in general, a description is also given of the Swedish Kiruna ore, with analyses of the different grades, now reduced to four in number, A, C, D, and G. These range from a low-phosphorus ore (A) with 0:015 per cent P, to a type with 8 per cent or more of phosphorus, due to a high proportion of apatite in the differentiated mass. The highest quality contains about 69 per cent Fe, and is one of the finest ores in the world. By agreement with the Swedish Government this quality is reserved for home consumption in Sweden, where it is transported by rail to the amount of about 50,000 tons perannum. Over 80 per cent of the whole export via Narvik consists of high phosphorus ores, D and G, specially adapted for basic steel. The last sixty pages of the memoir are occupied mainly by a discussion of the relative advantages of electric furnaces over ordinary blast furnaces for the home manufacture of pig-iron from Reports & Proceedings—Geological Society of London. 379 Norwegian ores. It is concluded that, owing to the abundance of water-power and absence of coal, the building of ordinary blast furnaces would be an economic mistake, since the fuel-consumption in an electric furnace is approximately only about one-third of that in a blast-furnace, and water power is cheap. It is estimated that the power consumption in an electric furnace is about 2,200 kilowatt- hours per ton of pig, which is equivalent to 2°98 tons of pig per kilowatt-year, or 2°92 tons per horse-power-year. Hitherto, the Swedish electric furnaces have been largely worked on charcoal, but coke is now extensively employed and gives good results. It is considered that small furnaces of the Tinfos type, working at about 1,500 kilowatts are not quite so economical as the larger Electro- metal furnaces of 3,500—4,000 kilowatts, but under certain circum- stances they are perhaps better suited to a budding industry, being altogether on a smaller scale and needing less capital outlay. From the data here supplied it is clear that in a country like Norway, with no coal and abundant water-power, electric furnaces offer great possibilities for the production of pig-iron for steel making for home consumption during periods of stress like the present time, when freights are high and dumping impossible, but it remains to be seen whether they will be able to compete with imported manufactured and half-manufactured goods on the return of more normal conditions of foreign competition and cheaper low-grade raw materials worked on a very large scale in England, America, and Germany. Tega Gs tse V.—Report on THE Grotocy or tHE Howoro Drsrricr, Parvan OrrrreLp. By W.G. Lanerorp. Bulletin of the Territory of Papua, No. 4, 16 pp., with 12 figs. and maps. Melbourne, 1918. ay this report Mr. Langford gives an account of the physiographic features and geology of part of the Vailala oil-bearing district of Papua, where the existence of gas-blows has been known for some time. The essential structure is an elongated dome or anticline traversed by faults and consisting of sandstones, mudstones, and limestones, with occasional seams of lignite of Middle or Upper Miocene age. The rocks are highly fossiliferous and the fossils are described in a separate report. Sites have been selected for trial bores, and development is now in active progress. REPORTS AND PROCHEHEDINGS. I.—Gronocicat Soctery or Lonpon. 1. June 4, 1919.—Mr. G. W. Lamplugh, F.R.S., President, in the Chair. The following communications were read :— 1. “On the Dentition of the Petalodont Shark, Climaxodus.”’ By Arthur Smith Woodward, LL.D., F.R.S., P.L.S., F.G.S. The author describes the nearly complete dentition of a new species of Climaxodus from the Calciferous Sandstone of Calderside, near Kast Kilbride (Lanarkshire), now in the Royal Scottish Museum, Edinburgh. Nearly all the teeth are borne on the 380 Reports & Proceedings—Geological Socrety of London. symphysis of the jaw, only the outer paired longitudinal series extending a little farther back over the rami. There are from three to five longitudinal series, each of five or six teeth of the ordinary Climaxodus type, covering the greater part of the sym- physis; and the flanking paired series, which extends farther back, comprises more depressed teeth, in which the cutting-edge forms a low blunt ridge. The two jaws are nearly similar; but, as in Janassa, the upper seems to have been slightly wider than the lower jaw. The teeth rapidly increase in size backwards, also as in Janassa, but they must have been all retained in the mouth throughout hfe; while in Janassa only a single transverse row would be in function at one time, the older teeth being thrust beneath to form a supporting base. Climarodus and Janassa are thus two distinct genera. These Petalodonts are especially note- worthy among the Elasmobranchii, because during the greater part of the life of each individual there cannot have been more than six or eight teeth in succession, a condition remarkably different from ordinary sharks and skates in which the successional teeth are always very numerous and rapidly replaced. The same limited tooth- succession is to be observed in the Carboniferous Cochliodontide, and perhaps also in the contemporaneous Psammodontide. Most of the teeth of Climaxodus are also interesting as showing a restricted area of highly vascular dentine much resembling a tritor in the dental plate of an ordinary Chimeroid. This character in Elasmobranch teeth which are peculiar for their slow and scanty succession, may have some special significance in connexion with the origin of the Chimeroids. 2. ‘* A New Theory of Transportation by Ice: the Raised Marine Muds of South Victoria Land (Antarctica).”’ By Frank Debenham, B.A., B.Se., F.G.S. A series of deposits of marine muds are found on the surface of floating ‘‘land-ice’? in the deep bays of Ross Sea (Antarctica). Similar deposits are also found on land up to a height of 200 feet, in some cases on old ice, in other cases on moraine. The deposits are briefly described, and former theories concerning them are discussed. A new theory is put forward, prefaced by an account of the nature of the typical ice-sheet which bears them. The upper surface of the sheet is known to suffer a net annual decrease, and evidence is given to show that the lower surface has a net increase by freezing from below. The theory is that the sheet will freeze to the bottom in severe seasons, and enclose portions of the sea-floor. Owing to the method of growth of the sheet by increments from below, the enclosed portions will ultimately appear on the surface, thus being raised vertically as well as translated horizontally. The application of the theory to other localities is briefly sketched, with especial reference to the shelly moraines of Spitsbergen and the shelly drifts of the glacial deposits of Great Britain. The general results of such a method of transportation are shown to be the raising of marine deposits above their initial level, the preservation of the organisms, the deposition of small patches of muds with Reports & Proceedings Geological Society of London. 381 ordinary supra-glacial moraine, and the collection of remains of fauna from different depths in one horizon. 2, June 25, 1919.—Mr. G. W. Lamplugh, F.R.S., President, in the Chair. The following communications were read :— 1. ‘‘Outlines of the Geology of Southern Nigeria (British West Africa), with especial reference to the Tertiary Deposits.” By Albert Ernest Kitson, C.B.E., F.G.S., Director of the Geological Survey of the Gold Coast. The oldest rocks in Southern Nigeria comprise a series of quartzites, schists of various kinds, blue and white marble, grey limestones, altered tuffs and lavas, amphibolites and gneisses. Their strike varies from west-north-west and east-south-east to north-east and south-west. They occur in the north-western portion of the country (Yorubaland), north of Jat. 7° N., and in the Oban Hills region in the east. They. may be classed provisionally as Pre- Cambrian. Intruded into these are large masses of granites of various kinds, syenite and diorite, with pegmatite and aplite dykes. In some parts these rocks have shared in the dynamic alteration to which the oldest series has been subjected; but usually they are practically unchanged. There is no definite evidence to show to what period they belong, but they are certainly Pre-Cretaceous, probably Middle and Karly Paleozoic. So far as observed, there is a great hiatus between the Pre- Cambrian and the next known sediments, the Upper Cretaceous. Normally, these are slightly inclined rocks: they include (1) Marine fossiliferous shales, mudstones, limestones, and sandstones in the great valley between the Oban Hills and the Udi plateau. The fossils are principally ammonites and molluseca; (2) Estuarine fossiliferous carbonaceous shales, mudstones, and sandstones along the eastern foot of the Udi escarpment; (3) Lacustrine sandstones, shales, and black coal-seams, with numerous plant-remains; and (4) Fluvio-lacustrine sands, shales, and pebble-bands in the lower and upper parts of the Upi plateau. Flanking this plateau on the south and south-east, and extending thence over the southern part of the great valley to the Cross River, is a series of Kocene estuarine shales, clays, and marls, with septarian nodules and pieces of coal and resin, and a rich fauna consisting principally of mollusca, but including fragmentary remains of whales, birds, fishes, and turtles. A thick series of sandstones, mudstones, shales, and seams of brown coal forms a large portion of the basin of the Niger, west of the Udi plateau. ‘These rocks appear to be of lacustrine origin, and are probably Eocene. They contain numerous remains of un- determined plants, largely of dicotyledonous types, Their relation to the Cretaceous and to the Eocene estuarine series is uncertain. In the Ijebu Jebu district are bituminiferous sands and clays with Pliocene estuarine shells. Extending over practically the whole of the country south of lat. 7° 10’ N., and west of the great valley of the marine Cretaceous 382 heports & Proceedings—Geological Society of London. isa varying thickness of (usually unstratified) clayey sands, probably late Pliocene—the Benin Sands Series of Mr. J. Parkinson. Along the coast-line and extending for considerable distances up the Niger and Cross Rivers are fluviatile, deltaic, littoral, and swamp gravels, sands, and muds of Pleistocene and recent age. In the Cross-River basin, intruded into the marine Cretaceous, are volcanic necks of decomposed agglomerate, and sills (?) and dykes of olivine- dolerite. These are probably Pre-Kocene. Faulting and local folding are visible in various portions of this district. Numerous silver-lead-zinc-iron lodes occur along these fault-lines, with brine-springs in several localities. The Yorubaland crystalline rocks contain magnetite in considerable quantities, while these and the crystalline rocks of the Oban Hills show smaller quantities of cassiterite, gold, monazite, and columbite. 2. ‘* Notes on the Extraneous Minerals in the Coral Limestones of Barbados.” By John Burchmore Harrison, C.M.G., M.A., F.G.S., F.I.C., and C. B. W. Anderson. Characteristic representative specimens of the fossil reef-corals and of the beach-rock of the high-level and low-level limestone terraces of Barbados were examined chemically and microscopically, in order to ascertain the composition, nature, and origin of their extraneous mineral contents. A special method was used, whereby the extraneous mineral matters were separated, practically without alteration, from large quantities of the limestones. Chemical analyses of the residua were made, and the results of these and of the microscopical examinations are tabulated in the paper. The extraneous minerals present were found to be apparently fresh and largely unaltered fragments of wind-borne volcanic minerals and glass. It was found that the voleanic minerals enclosed in the reef- corals on which they fell have been protected from change; those in the clastic limestone or bed-rock show signs of detrition and weathering prior to the consolidation of the limestone. Similar minerals separated from clay normally formed and accumulated in a pothole in the limestone supply evidence of weathering changes after being set free from the rock. It is shown that the composition of the sedentary residual soils on. the higher limestone terraces of Barbados corresponds in its essential parts with the residua separated, either naturally or artificially, from the limestone. The proportions of magnesium carbonate present in the coral-rock are briefly discussed, and complete analyses of the high-level and the low-level limestones are given. A note on the proportions of titanium oxide in the Barbados Oceanic clays and in some of the Challenger and Buccaneer deep-sea dredgings is appended to the paper. TI1.—Mrneratoeicat Socrery. June 17,1919.—Dr. A. E. H. Tutton, F-R.S., Past-President, in the Chair. A. E. Kitson: ‘Diamonds from the Gold Coast.” he crystals and their occurrence were described. 9 Reports & Proceedings—Mineralogical Society. 3838 * A. Brammall: ‘‘Andalusite (Chiastolite) ; its Genesis, Morphology, and Inclusions.’”? In a survey of thermometamorphic ‘ spotted”’ rocks evidence based on structural features, optical properties, and microchemical reactions is adduced to show that certain types of spots convergent towards such minerals as chiastolite, andalusite, cordierite, mica, and chloritoid record arrested development, and that they are probably ontogenetically related. The spot is a complex system containing a volatile phase, water, and its develop- ment involves metamorphic diffusion and differentiation controlled by changing conditions of temperature and stress, the tendency being towards the attainment of an equilibrium end-point in a metastable mineral. ‘Thermal and stress conditions adequate to initiate the tendency may be inadequate to sustain it, the time factor also being involved ; development may be arrested and abortive effort recorded as a mineral “spot”, the nature of which is determinable, but is often vague or wholly conjectural. The chemical and physical characters of argillaceous sediments are considered with special reference to the genesis of chiastolite. Clays contain a high pro- portion of hydrated silicates of alumina readily soluble and in part probably colloidal. On rise of temperature diffusion effects the segregation of the primary clot; diffusion inwards of allied molecules and diffusion outwards of alien substances tend to promote homo- geneity and reconstitution within the spot, the peripheral zone being maintained for a time in a relatively high state of hydration. In this connexion the peripheral zone of yellow-brown, non-pleochroic, and isotropic stain is significant ; microchemical tests show that it is due to ferric hydrates, which are known to be liable to spontaneous dehydration, and it is suggested that the ferric hydrate in the peripheral stain acts as a catalyst, assisting dehydration within the spot and transmitting water to the base. For chiastolite (andalusite) a mechanism of formation is suggested to cover the observed facts, to explain the characteristic distribution of its opaque inclusions, and to account for crystals which have the superficial aspect of cruci- form twins. R. H. Rastall: ‘‘The Mineral Composition of Oolitic Ironstones.”’ In many oolitic ironstones the ooliths contain more iron or are more highly oxidized than the matrix. Assuming that the iron-content of such rocks is introduced by metasomatism of calcium carbonate, this may be explained in the following way. Many ooliths and organic fragments in limestones consist of aragonite, while the cement is calcite. Aragonite is less stable than calcite and more readily decomposed by iron-bearing solutions, which therefore attack the aragonite first, while the calcite is replaced later. Hence we have the following scheme in successive stages :-— Ooliths. Aragonite —> Chalybite —> Limonite. Matrix. Calcite ——Calcite —>Chalybite. The ooliths are always a stage ahead of the matrix in replacement and oxidation. The origin of the green iron silicate, found in many ironstones, requires further investigation. L. J. Spencer: ‘‘ Eighth List of Mineral Names.” 384 Correspondence—F. Barke. ° ILI.—Grotocisrs Assocrarion. July 4, 1919.—Mr. J. F. N. Green, B.A., F.G.S., President, in the Chair. The following lecture was delivered: ‘‘The Geology of the - Llangollen District.” By L. J. Wills, M.A., F.G.S. - he lecture dealt with the following :— 1. The General Sequence of Rocks.—The Carboniferous, the Ludlow and Wenlock (Denbighshire type of Salopian Series), the Tarannon — Llandovery (Valentian Series), the Ashgillian and Caradocian (Bala Series). Notes on the fossils and zonal divisions and on the igneous rocks. 2. The General Structure.—The Carboniferous unconformity, the Llangollen synclinorium, the Berwyn and Cyrn-y-brain anticlines and the Bala fault, the cleavage and faulting. 3. The Glacial History of this Part of the Chester Dee.—The Welsh and Irish Sea ice-sheets in conflict, the phenomena of the retreat of the ice, the changes in the physical geography and effect on the human occupation. CORRHSPON DEN CEH. ———._ THE CARBONIFEROUS LIMESTONE OF THE WREKIN DISTRICT. Srtr,—In the February number of the Grotoercat MaGazine, p. 77, Mr. Parsons states that with the exception of one or two references to the Lower Carboniferous rocks of the area made in Geology in the Field, there does not appear to be any published description of the limestone of the district. | This statement overlooks the fact that a paper on ‘‘The Car- boniferous Limestone of Lilleshall” by Wheelton Hind, M.D., F.G.S., etc., is printed in the Trans. N. Staffs Field Club, vol. xxxv, pp. 107-9, 1900-1, giving a section of the beds nearer to Lilleshall Hill, just below the wharf. And again, some members of the geological section of the same club visited these quarries on a subsequent occasion, and a list of Corals, Crinoidea, and Brachiopoda observed are recorded in vol. xliii, p. 109, 1908-9. In the same number of the Gronocican Magazine, pp. 59-64, there is a paper ‘‘On the Discovery of a Quartzose Conglomerate at Caldon Low, Staffs” by J. Wilfrid Jackson, F.G.8., and W. E. Alkins, B.Sc. The writers of this paper report a discovery of an exposure of a quartzose conglomerate in a quarry at the Low. This deposit was discovered in 1905 by members of the Geological section of this club, and the fact recorded in the Trans., vol. xl, p. 85, 1905-6. F. Barxe, Chairman of Geological Section of N. Staffs Field Club. STOKE-ON-TRENT. June 6, 1919. _ WANTED and FOR SALE PETROLOGICAL and other MICROSCOPES, Microtomes, Spectroscopes, ete. BEST PRICES GIVEN. SEND FOR CATALOGUE. JOHN BROWNING (Estab. 1765), 146 Strand, Londen, W.C. 2. LIST OF BOOKS OFFERED FOR SALE AT THE NET PRICES AFFIXED BY DULAU & CO., LTD., 34-36 MARGARET STREET, CAVENDISH SQUARE, LONDON, W.1. BERICHTEH DER CHEMISCHER GESELLSCHAFT. 1882-92. Bd. xy—xxv in 31 vols. 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Plates for 1848 to 1866 are missing; the bindings are worn, and some titles are slightly defective. The late Professor R. O. Cunningham’s copy. Cloth, half-roan; and parts. £52. INDIAN GEOLOGICAL SURVEY DEPARTMENT. HE SECRETARY OF STATE FOR INDIA proposes to make four appointments to the Indian Geological Survey Department in August or September this year if so many qualified candidates are available. Preference will be given to candidates who have served in His Majesty’s Forces. Besides a good general education a sound education in Geology is essential; a University degree and a knowledge of French or German will be regarded as important qualifications. The age of candidates who have not served in His Majesty’s Forces should not exceed 25 years on July 1, 1919, but this limit will not be adhered to in the case of those who have served for one year at least, or who have been discharged after less than one year’s service on account of wounds or illness resulting from such service. 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