Societies and Academies

Abstract

LONDON. Geological Society, Mar. 18.—O. H. Schindewolf, On the septal development and the genotype of the coral genus Petraia Münster. The author, by showing that the genotype of Petraia is a synonym of Petraia radiata Münster, restricts the name to the Upper Silurian species. The Devonian species belong to Poĉta's genus Alleynia. Petraia, which is well characterised by its conical shape, deep calice, external ornamentation, arrangement of the septa, and, in normal specimens, by the absence of transverse tissue, has not been found outside Bavaria. W. B. R. King: A fossiliferous limestone associated with Ingletonian Beds at Horton-in-Ribblesdale, Yorkshire. The paper deals with an exposure of green felspathic grits with associated calcareous rocks in the railway cutting south of Horton-in-Ribblesdale station. The problems of general stratigraphy are discussed. There is much evidence of a general nature to suggest that although the limestone is undoubtedly of Ashgillian age, the grits with which it is associated must be considerably older. Calcareoits matter occurs in two forms in the cutting first, as the infilling between the grit blocks of a breccia, and secondly, as a crystalline fossiliferous limestone apparently inter-bedded with the grits. A detailed study of the limestone, however, shows that it is essentially of the same origin as the calcareous part of the breccia, since it contains angular fragments of grit and occasional flakes of roughly-cleaved green mudstone of a type exactly like the Ingletonian of the neighbourhood. The fossils show no signs of distortion by cleavage. It is suggested that this is another case of a ‘Neptunian dyke’.