TRANSACTIONS OF THE GEOLOGICAL SOCIETY OF LONDON. SECOND SERIES. VOLUME V. Quod si cui mortalium cordi et curae sit, non tantum inventis haerere, atque iis uti, sed ad ulteriora penetrare ; atque non disputando adversarium, sed opere naturam vincere; denique non belle et probabiliter opinari, sed certo et ostensive scire; tales, tanquam veri scientiarum filii, nobis (si videbitur) se adjungant. Novum Organum, Preefatio. LONDON: PRINTED BY B. AND J. E. TAYLOR, RED LION COURT, FLEET STREET. SOLD AT THE APARTMENTS OF THE GEOLOGICAL SOCIETY, SOMERSET HOUSE. 1840. TRANSACTIONS OF THE GEOLOGICAL SOCIETY OF LONDON. SECOND SERIES. VOLUME V. PART THE THIRD. Quod si cui mortalium cordi et curae sit, non tantum inventis hserere, atque iis uti, sed ad ulteriora penetrare ; atque non disputando adversarium, sed opere naturam vincere; denique non belle et probabiliter opinari, sed certo et ostensive scire; tales, tavvqwam veri scientiarum filii, nobis (si videbitur) se adjungant. Novum Organum, Prcefatio. LONDON: PRINTED BY R. AND J. E. TAYLOR, RED LION COURT, FLEET STREET. SOLD AT THE APARTMENTS OF THE GEOLOGICAL SOCIETY, SOMERSET HOUSE. 1840. OFFICERS AND COUNCIL OF THE GEOLOGICAL SOCIETY OF LONDON. 1840. PRESIDENT. Rev. WILLIAM BUCKLAND, D.D., F.R.S. & F.L.S., Instit. Reg. Soc. Paris. Corresp., Professor of Geology and Mineralogy in the University of Oxford. VICE-PRESIDENTS. GEORGE BELLAS GREENOUGH, Esq. F.R.S. Rev. WILLIAM WHEWELL, B.D., F.R.S., & F.L.S. Professor of Casuistry in the University of Cam­ LEONARD HORNER, Esq. F.R.S. L. & E. bridge. Sir WOODBINE PARISH, K.C.H. F.R.S. SECRETARIES. CHARLES DARWIN, Esq. B.A. F.R.S. J WILLIAM JOHN HAMILTON, Esq. FOREIGN SECRETARY. HENRY THOMAS DE LA BECHE, Esq. F.R.S.& F.L.S. TREASURER. JOHN TAYLOR, Esq. F.R.S. COl :IL. ARTHUR AIKIN, Esq. F.L.S. RODERICK IMPEY MURCHISON, Esq. FRANCIS BAILY, Esq. V.P.R.S. F.L.S., Instit. F.R.S. & F.L.S., Hon. M.R.I.A. Reg. Soc. Paris. Corresp. EDW. WILLIAM WYNNE PENDARVES, VISCOUNT COLE, M.P. F.R.S. Esq. M.P. F.R.S. WILLIAM HENRY FITTON, M.D. F.R.S. PHILIP PUSEY, Esq. M.P. F.R.S. & F.L.S. GEORGE RENNIE, Esq. F.R.S. WILLIAM HOPKINS, Esq. M.A. F.R.S. DANIEL SHARPE, Esq. F.L.S. ROBERT HUTTON, Esq. M.P. M.R.I.A. Rev. ADAM SEDGWICK, F.R.S. & F.L.S., CHARLES LYELL, Jun., Esq. F.R.S. & F.L.S. Woodwardian Professor in the University of WILLIAM HALLOWS MILLER, Esq. M.A. Cambridge. F.R.S., Professor of Mineralogy in the University of Cambridge. CURATOR AND LIBRARIAN. WILLIAM LONSDALE, Esq. ADVERTISEMENT. THE Editors of the Transactions of the Geological Society are directed to make it known to the Public, that the Authors alone are respon­ sible for the facts and opinions contained in their respective papers. It is requested that all letters and communications to the Secretariest and presents to the Society, may be addressed to the Apartments of the Geological Society, Somerset House, London. .