Prof. C. Lapicorfh— 0)1 Olenelhs Callavei. 535 



Series fixes the pre-Cambrian age of the Torriflon Sandstone. 

 Again, Dr. Katzer^ has shown that the strata of the Bohemian 

 Urgeberge (the Cambrian ^ of Barrande and Murchison — Etages A. 

 and \^.) lie (at least locally), unconformably below the rocks of the 

 true Cambrian or Primordial zone (a conclusion recently confirmed 

 by Dr. Wentzel^) and must, therefore, be now classed as pre-Cam- 

 brian or Archeean. In precisely the same way in two recent and 

 most valuable memoirs by M. Bergeron and M. Bigot we are 

 presented in one area (N.W. France) with clear physical proofs,* 

 and in another (Languedoc) with actual pala3ontologioal evidence,® 

 that the condensed Cambrian of Central Britain is apparently pro- 

 longed through France from the Channel Isles to the Montague 

 Noire ; and as a consequence the underlying (often unconformable) 

 schists of St. Lo, etc. — i.e. the Cambrian of Dalimier, Dufrenoy 

 and Murchison — may now be regarded as of Archaean or pre-Cam- 

 brian age. 



Thus while we have still very much to learn respecting the fossils, 

 the component members, and the local development of the ancient 

 Pala3ozoic strata, and while we must admit that many of our present 

 inferences and conclusions lie open to improvement and correction 

 by future investigation and discovery — the students of these old 

 rocks (however much they may conscientiously differ in the pro- 

 visional nomenclature in which they clothe their facts) have now 

 all more or less attained to the conviction that we are at last 

 reaching a satisfactory'^ homotaxial base to the Palseozoic rock-series. 

 We now see that the Lower Palaeozoic cycle of formations (the 

 Protozoic or Protogean) or the Silurian of Murchison's ' Siluria ' and 

 Barrande's ' Systeme ' has proved itself to be a geological cycle of 

 the first order. We agree, in principle, that it is made up (like 

 each of the succeeding great cycles), of three sub-equal groups® or 

 systems — an Upper system (the Silurian proper, or Salopian) a 

 Middle system (the Ordovician) and a Lower system (the Cambrian). 

 This lower system, like each of the two systems above it, has now 

 shown itself divisible in its turn into three sections — an Upper 

 Cambrian (Olenidian), a Middle Cambrian [Paradoxidian) and a 

 Lower Cambrian {Taconian). 



Underneath this Cambrian lie sometimes conformably, sometimes 

 unconformably, the strata of the mysterious cycles of the Pre- 

 Cambrian (or Archaean). Of these, certainly the rocks of the 

 unaltered divisions (the Eozoic or Eogean cycle) are now so well 

 circumscribed geographically that there appears little to hinder their 

 detailed study and investigation by an extension and development 



1 Dr. Fr. Katzer, Das altere Palseozoicum inMittel Bohmen, Prague, 1888, pp. 5, 7. 



2 Siluria, 4th edition, p. 273. 



3 Dr. Josef Wentzel, Die Beziehungen der Barrandischen Etagen C, D, E zum 

 Britischen Silur., Jahrbuch d. k. k Eeichsanstalt, Wien, 1891, p. 119. 



* A. Bigot, L'Archeen at le Cambrian du Massif Breton, Cherbourg, 1890, 

 pp. 25, 73, etc. 



^ J. Bergeron, Etude geologique du Massif ancien du Plateau Central, Paris, 1889, 

 p. 78, pi. ii. 



^ The Silurien superieur, Silurien moyen, and Silurien inferieur respectively, of 

 the younger French geologists. 



