Discussion.
Mr. Seeley remarked, as to the compressed spheroids found in so many rocks, that there was a difficulty in accepting the view of their originating in fluid vesicles, though he was unable to suggest any other theory by which to account for them. He observed that the eggs from the Stonesfield Slate closely resemble those of some birds in the pitting of the egg-shell, which differed from the pitting on such reptile- eggs as he had examined — and that it was of the highest interest to find such eggs in strata containing so many remains of ornithosaurian forms, such as Rhamphorhynchus and Pterodactylus, of which latter genus these were probably the eggs.
Prof. Rupert Jones fully recognized the ingenious explanation of the bubble-formed limited slickensides that looked so much like possible fossil fruits, and Mr. Carruthers's masterly treatment of the other specimens ; but he wished that the author would take up the subject exhaustively, and define the nature of other supposed vegetable fossils, such as the so-called fucoids, Paloeochorda, Paloeophyton, Oldhamia, &c, many, if not all, of which Prof. Jones thought to be due to galleries and other tracks made by Crustaceans.
Prof. Ramsay had known many instances of such blunders as those pointed out, made, not by experienced geologists, but by those unacquainted with the science. Though he had never regarded the flattened spheroids as fossils, he was unable to account for their presence in the clay-beds of different ages.
Mr. Hulke inquired whether Mr. Carruthers regarded the limited slickensides common in the Kimmeridge shales as due to gaseous origin. He remarked on the rarity of Pterodactylian remains as compared with those of other Saurians in the Wealden beds, in which the presumed eggs of Pterodactyle were found.
Mr. Seeley did not regard the Wealden egg as that of a Pterodactyle.
Mr. Carruthers, in reply, remarked that the local slickensides mentioned by Mr. Hulke differed in character from those to which he had referred.
2. Notes on the Geology of part of the County of Donegal.
By A. H. Green, Esq., F.G.S.
[Abstract.]
In this paper the author described the geological structure of the country in the neighbourhood of the Errigal Mountain, with the view of demonstrating the occurrence in this district of an interstratification with mica-schist of beds of rock which can hardly be distinguished from granite, the very gradual passage from alternations of granitic gneiss and mica-schist into granite alone, and the marked traces of bedding and other signs of stratification that appear in the granite, to which the author ascribed a metamorphic origin. He also noticed the marks of ice-action observed by him in this region, and referred especially to some remarkable fluted bosses of quartzite, and to the formation of some small lakes by the scooping action of ice.
vol. xxvii. — part i. 2 I
