472 Revieivs — C. I. Gardiner — Silurian of Usk. 



characterized by a low spiral angle, strong cancellate sculpture, 

 a much inflated body, and by a much excavated and reflected inner 

 lip, which conceals an umbilicus. It has a general resemblance to/ 

 Pyrifusus, and includes a species from the Senonian of Aachen, 

 referred by Miiller to the genus Hapa, and by Holzapfel to Tudicla. 

 Beferred to the Euomphalidae is a shell that has a flattened spire, 

 a deep wide umbilicus, of which the outer margin is conspicuously 

 produced, and an angular peripheral margin. It shows points of 

 resemblance and difference both with Discohelix and Straparollas, 

 and a new genus, Jffippocampoides (type, H. serratus, sp. nov.), is 

 instituted for it. Representatives of the Turbinidse and Delphinulidse 

 are also described. A new genus, Schizobasis, is assigned to the 

 former, and the genus JJrceoldbrum, also new, to the latter. Schizobasis 

 depressa is the type of a turbiniform genus that is characterized by 

 a short well-defined canal, a feature not found in any other members 

 of the Turbinidae. A conspicuous circular reinforced aperture, a deep 

 umbilicus, and au elevated cancellate spire are characters that typify 

 Urceolabrum tuberculatum, gen. et sp. nov., the genotype of a well- 

 defined group of forms new to the Delphinulidse. To this new genus 

 is also referred a form described by Miiller from the Aachen Beds as 

 Scalarta, and afterwards by Holzapfel as Liotia. 



III. — The Silurian Inlier of Usk. By C. I. Gardiner, M.A., 

 F.G.S. ; with a Palseontological Appendix, by F. B. C. Cowper 

 Bred, M.A., D.Sc, F.G.S. Proceedings of the Cotteswold 

 Naturalists Field Club, vol. xix, pp. 129-170, pis. vii and viii 

 and Geological Map. 



rPHE general structure of the inlier consists of two anticlines with 

 |_ a N.N.E.-S.S.W. trend separated from each other by a fault, 

 having the same general direction. The western, or Coed-y-paen, 

 anticline is more important than the eastern, or Llangibby, anticline 

 and brings the Wenlock Shale (the lowest exposed rock) to the 

 surface over a large area. The Wenlock Limestone comes in at 

 a somewhat indeterminate horizon, which is probably not quite the 

 summit of the Wenlock Shale, and over this the Ludlow rocks lie 

 conformably. There is no typical Downtonian, but the basement 

 bed of the Old Bed Sandstone overlies the Ludlow with very little 

 discordance in dip. The rocks of the Llangibby anticline as seen at 

 the surface belong almost entirely to the Ludlow series, and only at 

 one place is the Wenlock Limestone exposed ; however, three small 

 inliers of Old Bed Sandstone are brought in by minor synclines. 



Only on the south and west of the Coed-y-paen anticline does 

 the Old Bed Sandstone overlie the Ludlow rocks directly ; on all 

 other sides wherever it can be seen the boundary of the inlier is 

 a faulted one. The chief of these faults, like that dividing the two 

 anticlines, have a N.N.E.-S.S.W. direction ; but there is also another 

 series of faults in a more or less E.-W. dh'ection which are later than 

 the first-named series. These systems of faults must be referred to 

 the Pennine and Armorican foldings respectively, as they affect the 

 Old Bed Sandstone as well as the Silurian. 



