Prof. LapwortJi — Palceozoic Rocks of Britain ^ Scandinavia, 261 



and Salter, as exhibited in tlie typical localities in North Wales. 

 These limits define, with sufficient accuracy for our present purpose, 

 the strata containing the First or Primordial Fauna of Barrande, as 

 developed in Britain. In the rocks of this age, two distinct faunas 

 have long been universally recognized — a younger subfauna marked 

 by the preponderance of Trilobita of the genus Olenus and its most 

 intimate allies, and an older subfauna individualized by the exclusive 

 possession of the remarkable genus Paradoxides. Broadly speaking, 

 the Olenidian (or Olenus-heaving) rocks constitute the Upper 

 Cambrian of Hicks, and the Paradoxidian (or Paradoxides-heaxing) 

 his Lower Cambrian. But the genus Paradoxides has not hithei-to 

 been detected in the thick sandstones and flags that form the basal 

 zones of Hicks' Lower Cambrian. These have, as yet, yielded little 

 except the Annelide-burrows and markings (Scolithus, etc.) common 

 in sandy deposits of all ages. It is certain that traces of more 

 highly organized creatures will, in the future, be detected in these 

 basal beds, but it will, in the mean time, be found most convenient, 

 for purposes of comj^arison, to allude to these deep-seated zones as 

 the Annelidian or Scolithian beds of the Cambrian. 



Following generally the classification of the strata, containing the 

 British Primordial Fauna, proposed by Dr. Hicks, we may, at 

 present, regard the typical Cambrian System of Wales as being 

 composed of the following members : — 



(III.) Upper Cambrian of Hicks [Olenidian Division). 



(4) Tremadoc (Lower) Group of Belt and Dr. Callaway, with Asaphelhis 



Jlomfrayi, Dictyonema sociale, etc. 

 (3) Dolgelly Group of Belt, with ParaboUna spinulosa, Wahl., Feltura 



scarabeoides, Wahl. , etc. 

 (2) Festiniog Group of Belt, with Conocoryplie macrura. 

 (1) Maentwi'og Group of Belt, with Olenus yibbosus, Agnostus pisiformis, 

 Linn., etc. 

 Lower Cambrian of Hicks [Paradoxidian Division, etc.). 



(II.) Menevian Group of Hicks, with Paradoxides Davidis, Salt., etc. 

 (I.) Harlech Eocks of Hicks. 



(1) Superior Group, with Paradoxides, Plutonia, etc. 



(2) Inferior Group, with Annelides, Lingulella, etc. [Annelidian Division). 



The great fossiliferous Cambrian System of Wales, as thus defined, 

 is nearly three miles in vertical thickness, and reposes unconformably 

 below, both at St. Davids ' and in the Harlech Eegion,^ upon the 

 metamorphic rocks of the Archasan ; while in both these areas its 

 highest beds are surmounted with apparent conformity by the basal 

 zones of the succeeding Ordovian (or Lower Silurian) System, with a 

 new and distinct fauna. 



Cambrian System in Scandinavia. — Occupying a systematic j:)ositiou 

 identical with that of the Welsh Cambrian, we find in Scandinavia, 

 as the first of its Lower PalcBozoic Systems, a corresponding series 

 of fossiliferous sediinents, marked by a similar fauna. As in Wales, 

 also, this series is most conveniently regarded as being separable into 

 two main divisions ; a Lower Division of sandstones and grey wackes 

 resting unconformably upon the Archtean, and an Upper Division (the 



1 Hicks, Quart. Journ. Geol. Soc. 1877, p. 238, etc. 



2 Hicks, Geol, Mag. 1880, p. 529. 



