Societies and Academies

Abstract

LONDON Geological Society, May 14.—Mr. Joseph Prestwicb, F.R.S., vice-president, in the chair.—The following communications were read.—“On the genus Palæcoryne, Duncan and Jenkins, and its affinities,” by Prof. P. Martin Duncan, F.R.S.—In this paper the author referred to certain minute fossils from the Carboniferous rocks of Scotland, described by himself and Mr. Jenkins in a paper read before the Royal Society, as belonging to the Hydroido, and most nearly resembling the recent genus Bimeria, Wright. He stated that numerous specimens since received threw some further light on the nature of these fossils, and showed especially that ice all probability the base is not really cellular, but that the cellular appearance is produced by the growth of the real base of the polype over the cells of the Fenestella on which it grows.—“Notes on Structure in the Chalk of the Yorkshire wolds,” by Mr. J. R. Mortimer.—In this paper the author described a peculiar structure observable in chalk from Yorkshire and elsewhere, giving it a striated appearance. This structure bad been ascribed by Dr. Mackie and others to slickensides. The author adduced reasons for doubting the mechanical origin of these striations, and argued that they are of an organic nature. He ascribed them to corals, and remarked that similar striæ occur in all limestone formations.—“On Platysiagum sclerccephalum and Palæospinax priscus, Egerton,” by Sir P. de M. Grey-Egerton, Bart., M.P., F.R.S.—The two species of fossil Fishes noticed in this paper were described by the author in the 13th Decade of the Memoirs of the Geological Survey, published in 1872. They are both from the Lias of Lyme Regis. He now described some new specimens which add to our knowledge of their characters. An example of Platysiagum shows the position of the dorsal fin, which is placed very far back, occupying a place opposite to the interval between the ventral and anal fins, end the form of the trunk, which is of nearly uniform depth from the occiput to the base of the dorsal fin. The structure of the dorsal fin was described in detail. The new specimen of Palæospinax priscus shows especially the position of the second dorsal spine, which is placed over the 50th vertebra, the first being on the 16th, the fish thus most nearly approaching the existing Cestracion, which it also resembles in its dentition. In other respects it seemed to be most clearly allied to Acanthias.—“On a new genus of Silurian Asteriadæ,” by Mr. Thomas Wright, F.R.S.E.—The specimen described showed the outline of a small Starfish, with a large disc and short rays, in a slab of Wenlock Limestone from Dudley. The outline of the ten rays was described as marked out by the border of small triangular spines, the other plates of the disc and rays being absent. Each ray was terminated by a stemlike multiarticulate process as long as the ray, from towards the extremity of which spring slender lateral processes, giving it a tufted appearance. This Starfish, which is in the collection of Dr. Grindrod, is named by the author Trichotaster pluniformis.