Discoveries in the St. John Group. 137 



Europe by the illustrious Barrande, aud for Great Britain by Mr. 

 J. W. Salter and Dr. Henry Hicks. These students discovered 

 that while Paradoxides characterized the Lower Cambrian rocks, 

 the Upper Cambrian could be recognized by the presence in it, 

 among other fossils, of the crustacean genus Olenus. Dr. Hicks 

 went further, and was able to divide the Lower Cambrian formation 

 of Wales into three groups, by means of the different assem- 

 blages of animals which it contains. He thus established the 

 succession of the groups known as Caerfai, Solva, and Menevian. 



Prof. Hartt fixed the age of the St. John group as nearly as was 

 possible in his time, as Primordial, or, as we now call it, Cam- 

 brian ; but these latter discoveries in Europe have enabled the 

 writer to point out more exactly the Cambrian group in Wales 

 holding a fauna to which the beds containing the St. John fauna 

 described by Prof. Hartt correspond.* This has been shown in a 

 memoir in the Transactions of the Royal Society of Canada (1884) 

 and elsewhere, and we now know that Hartt' s species more nearly 

 represent those of the Solva group than those of the Menevian. 

 In other words, it is the fauna of the older part of the Lower 

 Cambrian. 



When we look for a source from which our Lower Cambrian 

 fauna may have been derived we are met with the difficulty that 

 no other large assemblage of animals of greater antiquity is known. 

 The oldest creature known, Eozoon canadense, so far preceded 

 in time the advent of the Cambrian forms of life that its influence 

 on them is almost beside the question. It is true that a species 

 resembling Eozoon canadense has been found in the pre-Cambrian 

 rocks of Bavaria, but the genus Eozoon is not known to have 

 left any successors or nearly related forms in the Cambrian lime- 

 stones, and may therefore be considered as practically extinct at 

 the opening of the Cambrian period. 



Coming to more recent times than that represented by Eozoon, 

 there is a Geological stage in Newfoundland indicated by the 

 Intermediate series of Mr. Alex. Murray, in which a single 

 organism has been found. This Intermediate series is regarded 

 by Mr. Murray and others as equivalent to the Huronian system 

 of Canada, and therefore intermediate between the Laurentian 



*The two groups, one in Wales and the other in Acadia, are not neces- 

 sarily on that account exactly cotemporaneous. 



