Front Matter

CONTENTS OF VOL. 159. I. Researches on Solar Physics. Heliographical Positions and Areas of Sun-spots observed with the Kew Photoheliograph during the years 1862 and 1863. By Warren De La Rue, Esq., Ph.D., F.R.S., F.R.A.S., Pres. C.S., Balfour Stewart, Esq., LL.D., F.R.S., F.R.A.S., Superintendent of the Kew Observatory, and Benjamin Loewy, Esq., F.R.A.S. .................................................. page 1 II. A Third Memoir on Skew Surfaces, otherwise Scrolls. By Professor Cayley, F.R.S. ........................................................................................................... 111 III. Description of the Great Melbourne Telescope. By T. R. Robinson, D.D., F.R.S., &c., and Thomas Grubb, Esq., F.R.S., &c. ........................................................................................................... 127 IV. The Formation and Early Growth of the Bones of the Human Face. By George W. Callender, Lecturer on Anatomy at St. Bartholomew's Hospital. Communicated by J. Paget, F.R.S. ........................................................................................................... 163 V. On Hydrofluoric Acid. By G. Gore, F.R.S. ................................................................................................................................. 173 VI. A Memoir on the Theory of Reciprocal Surfaces. By Professor Cayley, F.R.S. ........................................................................................................... 201 VII. A Memoir on Cubic Surfaces. By Professor Cayley, F.R.S. ........................................................................................................... 231 VIII. On the Osteology of the Solitaire, or Didine Bird of the Island of Rodriguez, Pezophaps solitaria (Gmel.). By Alfred Newton, M.A., Professor of Zoology and Comparative Anatomy in the University of Cambridge, and Edward Newton, M.A., Auditor-General of Mauritius. Communicated by P. L. Sclater, M.A., Ph.D., F.R.S. ........................................................................................................... 327 IX. On the Solar Variations of Magnetic Declination at Bombay. By Charles Chambers, Esq., Superintendent of the Colaba Observatory. Communicated by Balfour Stewart, F.R.S. ........................................................................................................... 363 X. Observations on the Development of the Semilunar Valves of the Aorta and Pulmonary Artery of the Heart of the Chick. By Morris Tonge, M.A., M.D. Communicated by Dr. Beale, F.R.S. ........................................................................................................... 387 XI. On the Diurnal and Annual Inequalities of Terrestrial Magnetism, as deduced from Observations made at the Royal Observatory, Greenwich, from 1858 to 1863; being a continuation of a communication on the Diurnal Inequalities from 1841 to 1857, printed in the Philosophical Transactions, 1863. With a Note on the Lunar-diurnal and other Lunar Inequalities, as deduced from observations extending from 1848 to 1863. By GEORGE BIDDELL AIRY, Astronomer Royal ................................................................................. page 413 XII. Spectroscopic Observations of the Sun.—No. II. By J. NORMAN LOCKYER. Communicated by Dr. SHARPEY, Sec. R.S .................. .......................................................... 425 XIII. Contributions to the Fossil Flora of North Greenland, being a Description of the Plants collected by Mr. EDWARD WHYMPER during the Summer of 1867. By Professor OSWALD HEER. Communicated by Professor STOKES, Sec. R.S .......... ......................................................... 445 XIV. Contributions to the History of Explosive Agents. By F. A. ABEL, F.R.S., Treas. Chem. Soc ..................................................................... .............. 489 XV. Description of the Cavern of Bruniquel, and its Organic Contents.—Part I. Human Remains. By Professor OWEN, F.R.S. &c. ............................................................................................................... . 517 XVI. Description of the Cavern of Bruniquel, and its Organic Contents.—Part II. Equine Remains By Professor OWEN, F.R.S. &c. ............................................................................................................... . 535 XVII. On Fossil Remains of Equines from Central and South America referable to Equus conversidens, Ow., Equus tau, Ow., and Equus arcidens, Ow. By Professor OWEN, F.R.S. &c. ............................................................................................................... . 559 XVIII. The Bakerian Lecture.—On the Continuity of the Gaseous and Liquid States of Matter. By THOMAS ANDREWS, M.D., F.R.S., Vice-President of Queen’s College, Belfast .......................................................................................... ... . 575 XIX. On the Specific Heat and other Physical Characters of Mixtures of Ethylic Alcohol and Water. By A. DUPRÉ, Ph.D., Lecturer on Chemistry at Westminster Hospital, and F. J. M. PAGE, B.Sc. Communicated by CHARLES BROOKE, F.R.S. ........................................................................................................................................... . 591 XX. On a certain Excretion of Carbonic Acid by Living Plants. By J. BROUGHTON, B.Sc., F.C.S., Chemist to the Cinchona Plantations of the Madras Government. Communicated by J. D. HOOKER, M.D., F.R.S. ................................................. .................................... 615 XXI. Researches on Turacin, an Animal Pigment containing Copper. By A. H. CHURCH, M.A. Oxon., Professor of Chemistry in the Royal Agricultural College, Cirencester. Communicated by Dr. W. A. MILLER, Treas. and V.P.R.S ....... .................................. ..... 627 XXII. On the Thermal Resistance of Liquids. By FREDERICK GUTHRIE. Communicated by Professor TYNDALL, LL.D., F.R.S ............... .................................................................................................................. . 637 XXIII. Researches into the Chemical Constitution of Narcotine, and of its Products of Decomposition.—Part III. By Augustus Matthiessen, F.R.S., Lecturer on Chemistry in St. Bartholomew's Hospital. . . . . . . . . . . . . . . . . . page 661 XXIV. Researches into the Chemical Constitution of Narcotine, and of its Products of Decomposition.—Part IV. By Augustus Matthiessen, F.R.S., Lecturer on Chemistry in St. Bartholomew's Hospital, and C. R. A. Wright, B.Sc. Lond. . . . . 667 XXV. Researches on Vanadium.—Part II. By Henry E. Roscoe, B.A., Ph.D., F.R.S. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 679 XXVI. On Palaeocoryne, a Genus of Tubularine Hydrozoa from the Carboniferous Formation. By P. Martin Dungan, F.R.S., Sec. Geol. Soc., and H. M. Jenkins, F.G.S., Sec. Royal Agric. Soc. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 693 XXVII. On Holtenia, a Genus of Vitreous Sponges. By Wyville Thomson, LL.D., F.R.S., Professor of Natural Science in Queen's College, Belfast . . . . . . . . . . 701 XXVIII. Description of Parkeria and Loftusia, two gigantic types of Arenaceous Foraminifera. By William B. Carpenter, M.D., V.P.R.S., and Henry B. Brady, F.L.S. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 721 XXIX. On the Structure and Development of the Skull of the Common Fowl (Gallus domesticus). By William Kitchen Parker, F.R.S. . . . . . . . . . . . . . . . . . . . . . 755 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 809 APPENDIX. Presents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [ 1 ] ERRATA. Page 134, last line of Note, insert + before 2ø. Page 158, in 5th column of Table, the number in line b. should be 24, and in line c. should be 5. Page 575, line 9, for 1826 read 1845. LIST OF ILLUSTRATIONS. Plates I. & II.—Messrs. De La Rue, Stewart, and Loewy's Researches on Solar Physics. Plates III. to XII.—Dr. T. R. Robinson's and Mr. T. Grubb's Description of the Great Melbourne Telescope. Plates XIII. & XIV.—Mr. George W. Callender on the Formation and Early Growth of the Bones of the Human Face. Plates XV. to XXIV.—Messrs. A. and E. Newton on the Osteology of the Solitaire. Plates XXV. to XXX.—Mr. C. Chambers on the Solar Variations of Magnetic Declination at Bombay. Plates XXXI. & XXXII.—Dr. M. Tonge on the Development of the Semilunar Valves in the Heart of the Chick. Plates XXXIII. to XXXVI.—The Astronomer Royal on the Diurnal and Annual Inequalities of Terrestrial Magnetism. Plates XXXVII. & XXXVIII.—Mr. J. N. Lockyer's Spectroscopic Observations of the Sun. Plates XXXIX to LVI.—Professor Heer on the Fossil Flora of North Greenland. Plates LVII. to LX.—Professor Owen's Description of the Cavern of Bruniquel, and its Organic Contents. Plates LXI. & LXII.—Professor Owen on Fossil Remains of Equines from Central and South America. Plate LXIII.—Dr. Andrews on the Continuity of the Gaseous and Liquid States of Matter. Plate LXIV.—Dr. A. Dupré and F. J. M. Page on the Specific Heat and other Physical Characters of Mixtures of Alcohol and Water. Plate LXV.—Mr. Frederick Guthrie on the Thermal Resistance of Liquids. Plate LXVI.—Messrs. P. Martin Duncan and H. M. Jenkins on Palaeocoryne. Plates LXVII. to LXXI.—Dr. Wyville Thomson on Holtenia. Plates LXXII. to LXXX.—Dr. W. B. Carpenter and Mr. H. B. Brady on two gigantic types of Arenaceous Foraminifera. Plates LXXXI. to LXXXVII.—Mr. W. K. Parker on the Structure and Development of the Skull of the Common Fowl (Gallus domesticus). The Committee appointed by the Royal Society to direct the publication of the Philosophical Transactions, take this opportunity to acquaint the Public, that it fully appears, as well from the Council-books and Journals of the Society, as from repeated declarations which have been made in several former Transactions, that the printing of them was always, from time to time, the single act of the respective Secretaries till the Forty-seventh Volume; the Society, as a Body, never interesting themselves any further in their publication, than by occasionally recommending the revival of them to some of their Secretaries, when, from the particular circumstances of their affairs, the Transactions had happened for any length of time to be intermitted. And this seems principally to have been done with a view to satisfy the Public, that their usual meetings were then continued, for the improvement of knowledge, and benefit of mankind, the great ends of their first institution by the Royal Charters, and which they have ever since steadily pursued. But the Society being of late years greatly enlarged, and their communications more numerous, it was thought advisable that a Committee of their members should be appointed, to reconsider the papers read before them, and select out of them such as they should judge most proper for publication in the future Transactions; which was accordingly done upon the 26th of March 1752. And the grounds of their choice are, and will continue to be, the importance and singularity of the subjects, or the advantageous manner of treating them; without pretending to answer for the certainty of the facts, or propriety of the reasonings, contained in the several papers so published, which must still rest on the credit or judgement of their respective authors. It is likewise necessary on this occasion to remark, that it is an established rule of the Society, to which they will always adhere, never to give their opinion, as a Body, upon any subject, either of Nature or Art, that comes before them. And therefore the thanks, which are frequently proposed from the Chair, to be given to the authors of such papers as are read at their accustomed meetings, or to the persons through whose hands they received them, are to be considered in no other light than as a matter of civility, in return for the respect shown to the Society by those communications. The like also is to be said with regard to the several projects, inventions, and curiosities of various kinds, which are often exhibited to the Society; the authors whereof, or those who exhibit them, frequently take the liberty to report and even to certify in the public newspapers, that they have met with the highest applause and approbation. And therefore it is hoped that no regard will hereafter be paid to such reports and public notices; which in some instances have been too lightly credited, to the dishonour of the Society. A List of Public Institutions and Individuals, entitled to receive a Copy of the Philosophical Transactions of each year, on making application for the same directly or through their respective agents, within five years of the date of publication. ### Observatories - Armagh - Cape of Good Hope - Dublin - Edinburgh - Greenwich - Kew - Liverpool - Madras - Oxford (Radcliffe) ### Institutions - Barbadoes - Birmingham - Calcutta - Geological Museum - Cambridge - Cape Town - Dublin - Royal Irish Academy - Edinburgh - London - Admiralty Library - Chemical Society - Entomological Society - Geological Society - Geological Survey of Great Britain - Institution of Civil Engineers - Institution of Naval Architects - Linnean Society - London Institution - Royal Asiatic Society - Royal Astronomical Society - Royal College of Surgeons - Royal College of Physicians - Royal Geographical Society - Royal Horticultural Society - Royal Institute of British Architects - Royal Institution of Great Britain - Royal Medical and Chirurgical Society - Royal Society of Literature - Society of Antiquaries - Society of Arts - The Queen's Library - The Treasury Library - The War Office - United Service Museum - Zoological Society - Malta - Manchester - Literary and Philosophical Society - Melbourne - University Library Montreal Oxford Swansea Sydney Woolwich McGill College Ashmolean Society Radcliffe Library Royal Institution University Library Royal Artillery Library ### Argentine Republic Buenos Ayres Museo Publico ### Belgium Brussels Académie Royale de Médecine Académie Royale des Sciences ### Denmark Copenhagen Kongelige Danske Videnskabernes Selskab ### France Montpellier Académie des Sciences et Lettres Faculté de Médecine Paris Académie des Sciences de l'Institut Dépôt de la Marine Ecole des Mines Ecole Normale Supérieure Faculté des Sciences de la Sorbonne Jardin des Plantes Société Entomologique Société de Géographie Société Géologique Société d'Encouragement pour l'Industrie Nationale Toulouse Académie Impériale des Sciences ### Germany Altona Die Sternwarte Berlin Königliche Akademie der Wissenschaften Physikalische Gesellschaft Brünn Naturforschender Verein Danzig Naturforschende Gesellschaft Dresden Kaiserliche Leopoldino-Carolinische deutsche Akademie der Naturforscher Frankfort Senckenbergische naturforschende Gesellschaft Giessen Grossherzogliche Universität Göttingen Königliche Gesellschaft der Wissenschaften Gratz Naturwissenschaftlicher Verein für Steiermark Hamburg Naturwissenschaftlicher Verein A List of Public Institutions and Individuals, entitled to receive a Copy of the Philosophical Transactions of each year, on making application for the same directly or through their respective agents, within five years of the date of publication (continued). Innsbruck . . . . . . Das Ferdinandeum. Jena . . . . . . Medicinisch-Naturwissenschaftliche Gesellschaft. Königsberg . . . . . Königliche physikalisch-ökonomische Gesellschaft. Leipzig . . . . . . Königlich Sächsische Gesellschaft der Wissenschaften. Mannheim . . . . . Grossherzogliche Sternwarte. Munich . . . . . . Königlich Bayerische Akademie der Wissenschaften. Prague . . . . . . Königlich böhmische Gesellschaft der Wissenschaften. Vienna . . . . . . Kaiserliche Akademie der Wissenschaften. Würzburg . . . . . Physikalisch-medicinische Gesellschaft. Hungary. Pesth . . . . . . Á Magyar Tudós Társaság—Die Ungarische Akademie der Wissenschaften. Italy. Bologna . . . . . . Accademia delle Scienze dell’ Istituto. Catanea . . . . . . Accademia Gioenia di Scienze Naturali. Florence . . . . . . Reale Museo di Fisica. Milan . . . . . . Reale Istituto Lombardo di Scienze, Lettere ed Arti. Modena . . . . . . Società Italiana delle Scienze. Naples . . . . . . 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A List of Public Institutions and Individuals, entitled to receive a Copy of the Astronomical Observations (including Magnetism and Meteorology) made at the Royal Observatory at Greenwich, on making application for the same directly or through their respective agents, within two years of the date of publication. | Observatories | Institutions | |------------------------|--------------------------------------------------| | Altona | Aberdeen University | | Armagh | Berlin Academy of Sciences | | Breslau | Boston American Academy of Sciences | | Brussels | Brunswick U.S. Bowdoin College | | Cadiz | Cambridge Trinity College Library | | Cambridge | Cambridge U.S. Harvard University | | Cape of Good Hope | Dublin University | | Coimbra | Edinburgh University | | Copenhagen | Dorpat Royal Society | | Dublin | Dublin University | | Edinburgh | Edinburg University | | Helsingfors | Glasgow University | | Königsberg | Göttingen University | | Madras | Leyden University | | Mannheim | London Board of Ordnance | | Marseille | London Royal Institution | | Milan | London Royal Society | | Munich | London The Queen's Library | | Oxford | Oxford Savilian Library | | Palermo | Paris Academy of Sciences | | Paris | Paris Bureau des Longitudes | | Seeberg | Paris Dépôt de la Marine | | Tübingen | Pesth Hungarian Academy of Sciences | | Turin | Philadelphia American Philosophical Society | | Vienna | St. Andrews University | | Wilna | St. Petersburg Imperial Academy | | | Stockholm Royal Academy of Sciences | | | Upsal Royal Society | | | Waterville, Maine (U.S.) College | | Individuals | | |------------------------|--------------------------------------------------| | Lowndes' Professor of Astronomy | Cambridge. | | Plumian Professor of Astronomy | Cambridge. | | President of the Royal Society | London. | | The Earl of Rosse | Parsonstown. | A List of Observatories, Institutions and Individuals, entitled to receive Copy of the Magnetical and Meteorological Observations made at the Royal Observatory, Greenwich. | Observatories | Individuals | |-------------------------------|----------------------------------| | Christiania | Buys Ballot, Dr. | | Gotha | Dove, Prof. H. W. | | Heidelberg | Erman, Dr. Adolph | | Kew | Fox, R. W., Esq. | | Kremsmünster | Hoskins, Dr. S. E. | | Leipzig | Kaemtz, Prof. L. F. | | Lisbon | Lloyd, Rev. Dr. | | Marburg | Loomis, Prof. E. | | Prague | Phillips, Prof. John | | Stockholm | Quetelet, Mons. A. | | St. Petersburg | Sabine, Lt.-General Sir E., R.A. | | | Souza, Senhor da | | | Wartmann, Prof. Elie | | | Younghusband, Col., R.A. | | Institutions | | |-------------------------------|--------------------------------| | Bombay | Geographical Society. | | Bonn | University. | | Cherkow | University. | | Falmouth | Royal Cornwall Polytechnic Society. | | London | House of Lords, Library. | | | House of Commons, Library. | | | Royal Society. | | | University College, Library. | | Paris | Meteorological Society. | | St. Bernard | The Hospice. | | Washington | Smithsonian Institution. | | Woolwich | Office of Mag. and Met. Publish- | | | | CONTENTS. I. Researches on Solar Physics. Heliographical Positions and Areas of Sun-spots observed with the Kew Photoheliograph during the years 1862 and 1863. By Warren De La Rue, Esq., Ph.D., F.R.S., F.R.A.S., Pres. C.S., Balfour Stewart, Esq., LL.D., F.R.S., F.R.A.S., Superintendent of the Kew Observatory, and Benjamin Loewy, Esq., F.R.A.S. ........................................... page 1 II. A Third Memoir on Skew Surfaces, otherwise Scrolls. By Professor Cayley, F.R.S. .................................................................................................................. 111 III. Description of the Great Melbourne Telescope. By T. R. Robinson, D.D., F.R.S., &c., and Thomas Grubb, Esq., F.R.S., &c. .................................................................................................................. 127 IV. The Formation and Early Growth of the Bones of the Human Face. By George W. Callender, Lecturer on Anatomy at St. Bartholomew's Hospital. Communicated by J. Paget, F.R.S. .................................................................................................................. 163 V. On Hydrofluoric Acid. By G. Gore, F.R.S. .................................................................................................................. 173 VI. A Memoir on the Theory of Reciprocal Surfaces. By Professor Cayley, F.R.S. .................................................................................................................. 201 VII. A Memoir on Cubic Surfaces. By Professor Cayley, F.R.S. .................................................................................................................. 231 VIII. On the Osteology of the Solitaire, or Didine Bird of the Island of Rodriguez, Pezophaps solitaria (Gmel.). By Alfred Newton, M.A., Professor of Zoology and Comparative Anatomy in the University of Cambridge, and Edward Newton, M.A., Auditor-General of Mauritius. Communicated by P. L. Sclater, M.A., Ph.D., F.R.S. .................................................................................................................. 327 IX. On the Solar Variations of Magnetic Declination at Bombay. By Charles Chambers, Esq., Superintendent of the Colaba Observatory. Communicated by Balfour Stewart, F.R.S. .................................................................................................................. 363 X. Observations on the Development of the Semilunar Valves of the Aorta and Pulmonary Artery of the Heart of the Chick. By Morris Tonge, M.A., M.D. Communicated by Dr. Beale, F.R.S. .................................................................................................................. 387 MDCCCLXIX. XI. On the Diurnal and Annual Inequalities of Terrestrial Magnetism, as deduced from Observations made at the Royal Observatory, Greenwich, from 1858 to 1863; being a continuation of a communication on the Diurnal Inequalities from 1841 to 1857, printed in the Philosophical Transactions, 1863. With a Note on the Lunar-diurnal and other Lunar Inequalities, as deduced from observations extending from 1848 to 1863. By George Biddell Airy, Astronomer Royal XII. Spectroscopic Observations of the Sun.—No. II. By J. Norman Lockyer. Communicated by Dr. Sharpey, Sec. R.S. ERRATA. Page 134, last line of Note, insert + before $2\phi$. Page 158, in 5th column of Table, the number in line b. should be 24, and in line c. should be 5. LIST OF ILLUSTRATIONS. Plates I. & II.—Messrs. De La Rue, Stewart, and Loewy's Researches on Solar Physics. Plates III. to XII.—Dr. T. Robinson and Mr. T. Grubb's Description of the Great Melbourne Telescope. Plates XIII. & XIV.—Mr. George W. Callender on the Formation and Early Growth of the Bones of the Human Face. Plates XV. to XXIV.—Messrs. A. and E. Newton on the Osteology of the Solitaire. Plates XXV. to XXX.—Mr. C. Chambers on the Solar Variations of Magnetic Declination at Bombay. Plates XXXI. & XXXII.—Dr. M. Tonge on the Development of the Semilunar Valves in the Heart of the Chick. Plates XXXIII. to XXXVI.—The Astronomer Royal on the Diurnal and Annual Inequalities of Terrestrial Magnetism. Plates XXXVII. & XXXVIII.—Mr. J. N. Lockyer on Spectroscopic Observations of the Sun. CONTENTS. XIII. Contributions to the Fossil Flora of North Greenland, being a Description of the Plants collected by Mr. Edward Whymper during the Summer of 1867. By Professor Oswald Heer. Communicated by Professor Stokes, Sec. R.S. page 445 XIV. Contributions to the History of Explosive Agents. By F. A. Abel, F.R.S., Treas. Chem. Soc. 489 XV. Description of the Cavern of Bruniquel, and its Organic Contents.—Part I. Human Remains. By Professor Owen, F.R.S. &c. 517 XVI. Description of the Cavern of Bruniquel, and its Organic Contents.—Part II. Equine Remains. By Professor Owen, F.R.S. &c. 535 XVII. On Fossil Remains of Equines from Central and South America referable to Equus conversidens, Ow., Equus tau, Ow., and Equus arcidens, Ow. By Professor Owen, F.R.S. &c. 559 XVIII. The Bakerian Lecture.—On the Continuity of the Gaseous and Liquid States of Matter. By Thomas Andrews, M.D., F.R.S., Vice-President of Queen's College, Belfast 575 XIX. On the Specific Heat and other Physical Characters of Mixtures of Ethylic Alcohol and Water. By A. Dupré, Ph.D., Lecturer on Chemistry at Westminster Hospital, and F. J. M. Page, B.Sc. Communicated by Charles Brooke, F.R.S. 591 XX. On a certain Excretion of Carbonic Acid by Living Plants. By J. Broughton, B.Sc., F.C.S., Chemist to the Cinchona Plantations of the Madras Government. Communicated by J. D. Hooker, M.D., F.R.S. 615 XXI. Researches on Turacin, an Animal Pigment containing Copper. By A. H. Church, M.A. Oxon., Professor of Chemistry in the Royal Agricultural College, Cirencester. Communicated by Dr. W. A. Miller, Treas. and V.P.R.S. 627 XXII. On the Thermal Resistance of Liquids. By Frederick Guthrie. Communicated by Professor Tyndall, LL.D., F.R.S. 637 XXIII. Researches into the Chemical Constitution of Nar cotine, and of its Products of Decomposition.—Part II. By Augustus Matthiessen, F.R.S., Lecturer on Chemistry in St. Bartholomew’s Hospital page 661 XXIV. Researches into the Chemical Constitution of Nar cotine, and of its Products of Decomposition.—Part IV. By Augustus Matthiessen, F.R.S., Lecturer on Chemistry in St. Bartholomew’s Hospital, and C. R. A. Wright, B.Sc. Lond. 667 XXV. Researches on Vanadium.—Part II. By Henry E. Roscoe, B.A., Ph.D., F.R.S. 679 XXVI. On Paleocoryne, a Genus of Tubularine Hydrozoa from the Carboniferous Formation. By P. Martin Duncan, F.R.S., Sec. Geol. Soc., and H. M. Jenkins, F.G.S., Sec. Royal Agric. Soc. 693 XXVII. On Holtenia, a Genus of Vitreous Sponges. By Wyville Thomson, LL.D., F.R.S., Professor of Natural Science in Queen’s College, Belfast 701 XXVIII. Description of Parkeria and Loftusia, two gigantic types of Arenaceous Fora- minifera. By William B. Carpenter, M.D., V.P.R.S., and Henry B. Brady, F.L.S. 721 XXIX. On the Structure and Development of the Skull of the Common Fowl (Gallus domesticus). By William Kitchen Parker, F.R.S. 755 Index 809 APPENDIX. Presents [1] ERRATUM. Page 575, line 9, for 1826 read 1845. LIST OF ILLUSTRATIONS. Plates XXXIX. to LVI.—Professor Heer on the Fossil Flora of North Greenland. Plates LVII. to LX.—Professor Owen's Description of the Cavern of Bruniquel, and its Organic Contents. Plates LXI. & LXII.—Professor Owen on Fossil Remains of Equines from Central and South America. Plate LXIII.—Dr. Andrews on the Continuity of the Gaseous and Liquid States of Matter. Plate LXIV.—Dr. A. Dupré and F. J. M. Page on the Specific Heat and other Physical Characters of Mixtures of Alcohol and Water. Plate LXV.—Mr. Frederick Guthrie on the Thermal Resistance of Liquids. Plate LXVI.—Messrs. P. Martin Duncan and H. M. Jenkins on Palaeocoryne. Plates LXVII. to LXXI.—Dr. Wyville Thomson on Holtenia. Plates LXXII. to LXXX.—Dr. W. B. Carpenter and Mr. H. B. Brady on two gigantic types of Arenaceous Foraminifera. Plates LXXXI. to LXXXVII.—Mr. W. K. Parker on the Structure and Development of the Skull of the Common Fowl (Gallus domesticus). ADJUDICATION of the Medals of the Royal Society for the year 1869 by the President and Council. The Copley Medal to M. Henri Victor Regnault, For. Mem. R.S., for the second volume of his "Relation des expériences pour déterminer les lois et les données physiques nécessaires au Calcul des Machines à feu;" including his elaborate investigations on the Specific Heat of Gases and Vapours, and various papers on the Elastic Force of Vapours. A Royal Medal to Sir Thomas Maclear, F.R.S., for his Measurement of an Arc of the Meridian at the Cape of Good Hope. A Royal Medal to Dr. Augustus Matthiessen, F.R.S., for his researches on the electrical and other physical properties of Metals and their Alloys. The Bakerian Lecture was delivered by Dr. Thomas Andrews, F.R.S.; it was entitled "The Continuity of the Gaseous and Liquid States of Matter." The Croonian Lecture was not delivered.