638 EDWABD HULL ON THE CLASSIFICATION Anthracosia, Productiis carbonarius, P. semireticulatus, and Strep- torhynchus crenistria, is considered to be the representative of the Chance Pennystone of Coalbrookdale, and is included in the Middle Coal-measures. Notwithstanding the freshwater conditions that appear to have prevailed throughout the great mass of the Coal-measures of Prance and Belgium, brackish-water or estuarine conditions, consequent on slight depressions below the sea-level of the period, occurred at several intervals, so that out of twelve fossiliferous stages described by MM. Cornet and Briart five contain C'ardinia and Posidonomya. In the 12th stage marine fossils occur which M. Charles Barrois assigns to the zone of " the Chance Pennystone " of Coalbrookdale*. The same observer has discovered Productiis carbonarius in " le gres des Plaines" in the Boulonnais at the base of the Coal-formation, which he considers as probably representing the Millstone Grit of England. (3) Germany. Silesia. — In August of 1862 the attention of Prof. Ferd. Homer was called to the existence of marine shells at two collieries in Upper Silesia, in strata of shale lying near the base of the productive Coal-measures of that district. The beds contain- ing these fossils consist of dark shales about 100 feet in thickness, and upon further examination yielded a large number of forms, de- scribed and figured in Dr. Homer's paper f- They are as follows — Phillipsia (sp. inc.), Orthoceras undatum, 0. dilatatum, 0. telescopio- lum (n. sp.), Nautilus subsulcatus, Nautilus concavus, N. nodoso- carinatus (n. sp.), Goniatites diadema, G. Listeria Bellerophon XJrii, Littorina obscura, Anthracosia ? (n. sp.), Schizodus sulcatus, Leda attenuata, Nucula gibbosa, Area Lacordairiana, Pecten (sp. inc.), P. interstitialis, Productus longispinus, P. semireticulatus, P. pustu- losus, Orthis resupinata, 0. crenistria, Lingula mytiloides, Piscina nitida, Poteriocrinus, and plants — Noeggerathia, Catamites, Trigono- carpum. Dr. Homer very aptly points out the resemblance of this fauna to that of the Pennystone beds of Coalbrook Dale, described by Professor Prestwich, and to that of the Gannister beds of Yorkshire, described by the late Professor Phillips. There can, in fact, be no doubt whatever that the beds in which they occur are the represen- tatives of those just named. Out of the species above enumerated there are no less than 9 which are known as occurring in the Gan- nister-beds in the British Isles, viz. Phillipsia (genus), Nautilus concavus, N. subsulcatus, Goniatites Listeria, Littorina obscura, Schizodus sulcatus, Productus semireticulatus, Orthis resupinata, Lin- gula mytiloides, and Piscina nitida. Here again we find representa- tives of the genus Anthracosia associated with marine forms. (4) Westphalia. — The marine zone at the base of the productive
- Loc. supra cit. pp. 225, 226.
t Supra cit.
This may be considered the characteristic shell of Stage E in Lancashire,
Yorkshire, and Derbyshire. The species of Phillipsia is probably pustulata, which occurs (as we haye seen) in the beds of this stage at Castlecomer in Ireland.
