MENEVIAN SERIES. 59 



The Rev. W. S. Symonds remarks that the Cambrian beds of the 

 Longmynds are continued into the smaller range of the Haugh- 

 mond Hills near Shrewsbury, and that the exudation of mineral 

 pitch or bitumen from these old rocks is very remarkable.^ This 

 bitumen may have been derived from Coal-measures which formerly 

 occurred over these rocks. 



MENEVIAN SERIES. 



The term Menevian, from Menasvia, the old Roman name of the 

 district of St. Davids, was proposed by Mr. J. W. Salter and Dr. Hicks 

 (in 1865) for a series of black and grey slates and blue and grey 

 flags with thick beds of sandstone, which underlie the true Lingula 

 Flags, and attain a thickness of 600 feet or more. They overlie the 

 Harlech rocks conformably around the Merionethshire anticlinal ; 

 the junction may be seen about half a mile east of Barmouth. 



The Menevian Beds contain many species of Trilobites, amongst 

 which the large Paradoxides Davidis, sometimes nearly two feet in 

 length, is conspicuous. It was discovered by Mr. J. W. Salter 

 in 1863. Hence the term Paradoxidian applied in part to this group. 

 (See p. 52.) Among other fossils are Agnostus sciitalis, A. Davidis, 

 Conocoryphe coroiiaia, Microdiscus punctatus, Erinnys venulosa, Proto- 

 spongia fenestrata, and Theca corrugata. Most of the characteristic 

 fossils are as yet unknown in the beds above. One Cystidean 

 makes its appearance. 



The INIenevian beds are developed at St. Davids in South Wales, 

 and in the neighbourhood of Maentwrog, Dolgelly, Tyddyngwladis, 

 and Tafarn Helig, in North Wales. They have not yet been 

 distinguished in the Longmynd area. At St. Davids the beds are 

 very fossiliferous, and so closely related palaeontologically to the 

 Harlech or Longmynd group that Dr. Hicks (in 1867) proposed 

 to class the two groups together as Lower Cambrian. 



The following divisions have been made '} — 



^Upper. — Sandstones and shales, with OriJiis Hicksii, 



Obolella sa git talis. 100 feet. 

 Middle. — Black flags, with Paradoxides Davidis, 

 Menevian. i Agnostus saitalis. 350 feet. 



Lower. — Grey flags, with Paradoxides Hicksii, Obolella 

 sagittalis, Agnostus Barrandei, Conocoryphe coro- 

 nata. 300 feet. 



An interesting account of phosphates in these and other Cambrian 

 rocks has been given by Dr. Hicks ; and he states his opinion that 

 much of the material may have been derived from Trilobites." 



^ Records of the Rocks, p. 49. 



" Harkness and Hicks, Q. J. xxvii. 396. See also P. Geol. Assoc, iii. 99, 

 where the Middle and Upper divisions are grouped as one by Dr. Hicks; and 

 C. Lapworth, G. Mag. 1881, p. 321. Also G. Mag. 1868, p. 306, Q. J. xxv. 

 51, andxxxi. 168. ^ q_ j_ j-xxi. 376. 



