found both at Dolgelly and in Pembrokeshire, about a hundred feet above the lowest black Lingula-slates."
Respecting the discovery of another form, Paradoxides Davidis, Salter, in Pembrokeshire, the late Mr. Salter has described this species, and named the locality whence it has been obtained*.
In this memoir a Table is also given of the strata which make up the " Lingula-flags in Wales ;" and Mr. Salter has described the lower portion of this series as a "thick mass of black shales very uniform in its upper part, but with hard sandstones in the lower, probably accumulated in a deep sea." The fossils of the Lower Lingula-flags are stated to be " Lingulella, rare, Olenus, common, Agnostus, common, Paradoxides Davidis" †.
Subsequently Mr. Salter, in a communication entitled " On some New Fossils from the Lingula-flags of Wales," described and figured several new forms of Trilobites, a Theca, and a large Sponge obtained from the dark-coloured rocks of Porth-y-Rhaw by Mr. Hicks‡.
In this memoir a section is given of the fossiliferous rocks, showing their relation to the purple and green sandstones on which they repose.
In 1865 Mr. Salter alludes to the occurrence of " Some additional Fossils from the Lingula-flags ;" and a note on the genus Anopolenus is appended to this communication by Mr. Hicks §. The lower portion of these Lingula-flags affording the additional fossils, and also those previously referred to, were designated by Messrs. Salter and Hicks, in a paper read at the British Association in 1865, the " Menevian group."
In 1867 a new form of Lingulella (L. ferruginea, Salter), from the Lower Lingula-flags of St. David's, was described ; and the occurrence of a variety of the same, Lingulella ferruginea, var. ovalis, Hicks, which had been obtained from the underlying red rocks, was alluded to || .
In this communication of Messrs. Salter and Hicks we have the first indication of the presence of fossils in the purple and green rocks of the St. David's promontory, upon which the Lower Lingula- flags are superposed.
In 1868 Messrs. Salter and Hicks gave an abstract having reference to the occurrence of some new fossils from the Menevian group (Lower Lingula-flags) ; and in 1869 a detailed description was given of these fossils¶.
The discovery of fossils in the dark-coloured Lower Lingula-flags
- Quart. Journ. Geol. Soc. vol. xix. p. 275.
† This description of the Lower Lingula-flags was correct so far as then recognized in North Wales ; but it does not include that very important portion at the base, which has since been separated by Messrs. Salter and Hicks, and named the Menevian group. Paradoxides Davidis belongs to this group, and should not be associated with Olenus, the typical genus of the Lingula-flags proper.
‡ Op. cit. supra, vol. xx. p. 233.
§ Op. cit. supra, vol. xxi. p. 477.
|| Op. cit. supra, vol. xxiii. p. 339.
¶ Op. cit. supra, vol. xxiv. p. 519, and xxv. p. 51.
VOL. XXVII. PART I. 2 E
