392 PEOCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 10, 



There is one very prominent feature abont the palaeontology of 

 the ancient rocks of St. David's : this is the occurrence of four dis- 

 tinct species of the genus Paradoxicles ; and this feature contrasts 

 very strongly with the entire absence of the genus Olenus from these 

 rocks. 



On a comparison of the palaeontology of the St. David's rocks 

 with those of the continent of Europe and of America, which seem 

 to occupy nearly the same horizon, we have like features, to a very 

 great extent, presenting themselves. 



The lower fossiliferous horizon of Sweden, the Alum-shales, has 

 been divided by Angelin into two groups. The lowest of these, 

 " Eegio B," contains forms of Faradoxides, among which we learn 

 that Dr. Otto Torell has recognized two species that are St.-David's 

 forms, viz. P. Davidis and P. Hicksii. The upper portion of the 

 Alum-shales of Sweden, " Regio A" of Angehn, contains several forms 

 of Oleni ; and from this portion of the series the genus Paradoaoides 

 seems to be absent. 



The deposits upon which the Alum-shales of Sweden rest, the 

 " Fucoidal Sandstones," contain within them purple beds ; and 

 from these we have reason to believe that evidence of life has been 

 obtained by Dr. Otto Torell in the form of an Oholella. In Sweden 

 the genus Paradoxides is found accompanied by Gonocoryphe [Cono- 

 cephalites) ; and Trilobites of this genus are also found associated 

 with Paradoxides in the St, David's promontory. 



Regie B of Angelin is represented by the dark- coloured rocks of 

 Porth-y-Bhaw ; and below these are strata which seem to be the 

 equivalents of the Pucoidal Sandstones of Sweden, yielding an ex- 

 tensive series of fossils. 



In N. Wales, on the E. and N.E. side of the Merionethshire 

 anticlinal, Begio B is also represented, and is succeeded by the 

 equivalents of Regie A, which, in the form of a thick series of 

 dark-coloured sandstones and shales (Lingula-flags), contain several 

 species of the genus Olenus. 



In Bohemia, the primordial zone of Barrande, as shown by its 

 fossil contents, is very near to the horizon of the Menevian group as 

 exhibited in Wales. Trilobites appertaining to the genera Para- 

 doxides, ConocorypJie, EllipsocepJialus, Sao, and Agnostus occur ; 

 but no traces of the genus Olenus have been obtained from the 

 Bohemian primordial rocks. 



In Bavaria, Sir R. I. Murchison states that, in the neighbourhood 

 of Hof, the primordial zone, " which consists of black siliceous slate, 

 above 50 feet thick, contains Trilobites, which have been determined 

 by Barrande to belong to ConocorypJie and Olenus ; " and in a letter 

 from M. Barrande to Sir Roderick it is said that •' with these pri- 

 mordial Trilobites are also associated two or three forms which every- 

 where characterize the second Silurian fauna (Llandeilo and Caradoc), 

 i. e. Calymene and Cheirurus"* . 



W^ith reference to the fauna of the primordial zone of Hof, Bar- 

 rande has remarked on the absence of the genus Paradoxides there- 

 * Quart. Journ. Geol. Soc. vol. xix. p. 362 ; Siluria, 4lli edit. p. 374. 



