62 



Menevian Beds. 



overlie the Cambrian strata, have been classed under 

 various subdivisions, from the presence in each of 

 certain Trilobites and other fossils, sometimes peculiar 

 to, and sometimes more or less prevalent in, each sub- 

 formation. To the oldest of these the name Menevian 



FIG. 15. 



Protocystites 

 Menevensis. 



Paradoxides aurora. 



Arionellus longicephahis. 







Conocoryphe coronata. Protospongia fenestrata. Discina pileolus. 



Group of Menevian Fossils. 



beds has been given, so called from Menapia, the old 

 Koman name of St. David's. They are of inconsider- 

 able thickness, and are found both in that district 

 and in North Wales, circling round the Cambrian rocks 

 of Merionethshire from Barmouth to Harlech, and in 



