Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/532

 Hicks, Conocoryphe Lyellii, Hicks, Microdiscus sculptus, Hicks, Agnostus cambrensis, Hicks, Protospongia fenestrata, Salter, Theca antiqua, Hicks, and Paradoxides Harknessi, Hicks.

The yellowish-coloured sandstones and shales are well seen on their line of strike in most of the headlands which intervene between Porth Clais Harbour and Caer-bwdy. The principal spot from which fossils have been obtained is the second headland E. of Porth Clais Harbour. The same rocks can be seen also between Folly and Trelerwr. Their thickness amounts to about 150 feet ; and on the N.N.W. side of the axis their equivalents occur in a nearly allied form, being yellowish -grey sandstones.

Succeeding these are grey rocks with purple bands, which pass upwards into purple and red sandstones and shales ; and from these Lingulella ferruginea, var. ovalis, Conocoryphe solvensis, Paradoxides Harknessi, and several of the other species have been obtained between Solva and Whitchurch. The total thickness of the two series on the S.S.E. side of the axis is about 700 feet. On this side of the axis these rocks are intersected by lines of faults, which run parallel to their strike ; and one of these extends from the coast a little S. of Folly through Trelerwr. These faults have downthrows on their S.S.E. side, which have reduced very materially the absolute thickness of those rocks on this side the promontory.

On the E. side of Ramsay Sound, and on the N.N.W. side of the axis, the equivalents of the grey and purple sandstones do not seem to have been affected by faults ; and here they have a thickness of about 1500 feet.

On this side of the ridge also the grey and purple sandstones have their representatives in the form of grey, purple, and red flaggy beds.

On the S.S.E. side the grey and purple sandstones have, resting conformably upon them, grey grits, which contain Paradoxides aurora, Salter, and Conocoryphe bufo, Hicks ; and these two forms have not, up to the present time, been discovered in strata which underlie or overlie the grey grits. Agnostus cambrensis and Theca antiqua have also been obtained from these grey beds. These two species also occur in the underlying rocks ; but they have not yet been met with in deposits higher than the grey grits. Discina pileolus, Hicks, and Obolella sagittalis, Salter, are also found in the grey beds. They likewise occur in the underlying purple strata, and they extend upwards through the Menevian group.

Lingulella ferruginea is also found in the grey beds ; and this form has the widest range of any of the fossils that have been obtained from the purple and green rocks of the St. David's promontory. It occurs in the lowest fossiliferous zone which has hitherto been discovered, and it extends through the Menevians. Theca penultima, Hicks, also occurs in these grey rocks ; and this is the lowest horizon from which it has been procured. Its range seems limited, as it has not been met with above the lower portion of the Menevians.

On the N.N.W. side of the axis, on the E. shore of Ramsay