CAMBRIAN AND SILURIAN IN EUROPE. [XV. 



time, noticed about this horizon certain graptolites ami an 

 Asaphus, which were supposed to belong to the Tremudi.e 

 slates, but have since been declared by Salter to pertain to the 

 Arenig or Lower Llandeilo beds, the base of the Upper Cam- 

 brian. (Mein. Geol. Sur., III. 257, and Decade II.) 



This discovery of the Lingula flags, as they were then named, 

 and the fixing by Sedgwick of their geological horizon, was at 

 once followed by a careful examination of them by the govern- 

 ment surveyors, and in 1847, Selwyh detected in the Lingula 

 flags, near Dolgelly, in Merionethshire, the remains of two 

 crustacean forms, the one a phyllopod, which has received the 

 name of Hymenocaris vermicauda, Salter, and the other a 

 trilobite which was described by Salter in 1849 as (> 

 micrurus. (Geol. Survey, Decade II.) A species of Para- 

 doxides, apparently identical with P. ForchJiammeri of Swe- 

 den, was also about this time recognized among specimens 

 supposed to be from the same horizon. It has since been de- 

 scribed as P. Hicksii, and found to belong to the basal beds of 

 the Lingula flags, the Menevian group. 



Upon the flanks of the Malvern Hills there is found resting 

 upon the ancient crystalline rocks of the region, and overlaid 

 by the Pentamerus beds of the May Hill sandstone (originally 

 called Caradoc by Murchison) a series of fossiliferous IK !.<. 

 These consist in their lowest part of about 600 feet of greenish 

 sandstone, which have since yielded an Obolella ami Sn-pu- 

 lites, and are overlaid by 500 feet of black schists. In tln-sr, 

 in 1842, Professor John Phillips found the remains of trilo- 

 bites, which he subsequently described, in 1848, as tlm-e 

 species of Olenus. (Mem. GeoL Survey, II. Part I. 55.) 

 These black shales, which had not at that time furnished any 

 organic remains, were by Murchison in his Silurian System 

 (p. 416) in 1839 compared to the supposed passage-beds in 

 Caermarthenshire between the Llandeilo and the Cambrian 

 (Bala) rocks ; which, as we have seen, were newer and not 

 older strata than the Llandeilo flags. From their HthotagiciJ 

 rliara* -ters, and their relations to the Pentamerus beds, thcs.- 

 lower fossiliferous strata of Malvern were subsequently referred 



