The Cambrian Horizons of Comley (Shropshire), and their Brachiopoda, Pteropoda, Gasteropoda, etc.

Abstract

I. Introduction. The objects of this paper are to define the horizons of the Cambrian system at Comley, to describe and illustrate the species of brachiopoda, pteropoda, and gasteropoda, and to discuss the relationships of the faunas one to the other and to those of other Cambrian areas. The majority of the specimens now described were obtained from the excavations carried out between the years 1907 and 1914, on behalf of the Committee for the Excavation of Critical Sections in Palaeozoic Rocks, appointed by the British Association for the Advancement of Science. Some specimens were collected in 1892 for H.M. Geological Survey by Mr. J. Rhodes, and others have been obtained by myself or other observers at various dates since 1890. II. The Comlet Horizons. Details of the sections opened by excavation have been given in the reports of the meetings of the British Association held at Dublin in 1908, Winnipeg in 1909, Sheffield in 1910, Portsmouth in 1911, Dundee in 1912, and Manchester in 1915. In Table I (facing p. 326) the various horizons from which different assemblages of fossils have been obtained are set out in descending order, with the proposed nomenclature in spaced type, followed by index-letters, thicknesses, general lithological characters, and suggested correlations. The designations used by me in previous communications and in my reports to the British Association are inserted in ordinary type in the first column. Since these differ considerably from those now proposed, a few words of explanation seem to be necessary. As