Note 65 — J. E. MARR, M.A., F.R.S. (continued 3)

A general account of the Cambrian, Ordovician and Silurian rocks will be found in the Sedgwick Essay for 1883, A Classification of the Cambrian and Silurian Rocks, though the use of a cumbrous nomenclature therein will tend to confuse the reader. For a detailed account of the Cambrian rocks of North Wales the reader is referred to the Geological Survey Memoir, The Geology of North Wales, by Sir A. Ramsay (2nd edition), he may also consult Belt, T., "On the Lingula Flags or Festiniog Group of the Dolgelly district," Geol. Mag., Dec I. vol. IV. pp. 493, 536, vol. V. p. 5. The geology of the Cambrian rocks is described in a series of Memoirs in the Quarterly Journal of the Geological Society by Dr H. Hicks; the following should be consulted: Harkness, R. and Hicks, H., "On the Ancient Rocks of the St David's Promontory, South Wales, and their Fossil Contents," vol. XXVII. p. 384; Hicks, H., "On some Undescribed Fossils from the Menevian Group," vol. XXVIII. p. 173; and "On the Tremadoc Rocks in the neighbourhood of St David's, South Wales, and their Fossil Contents," vol. XXIX. p. 39. See also Hicks, "The Classification of the Eozoic and Lower Palæozoic Rocks of the British Isles," Popular Science Review, New Series, vol. V., and Hicks, "Life-zones in the Lower Palæozoic Rocks," Geol. Mag. Dec IV. vol. I. pp. 368, 399 and 441.