THE 



CANADIAN RECORD 



OF SCIENCE. 



vol. iv. july, 1891. no. 7. 



On a New Horizon in the St. John G-roup. 



By G. F. Matthew, M.A., F.R.S.C. 



Read at Meeting of the Natural History Society of New Brunswick, 5th 

 October, 1891. 



Among fossils which are considered to be of special im- 

 portance in determining the age of Cambrian strata, none 

 are thought to be of greater value than that curious net- 

 like organism called Dictyonema flabelliforme. 



Most of the continental geologists regard the beds which 

 contain this fossil as the highest which should come under 

 the name of Cambrian, as distinguished from Ordovician or 

 Lower Silurian, because at these beds there is an important 

 palceontological break which we now know to be only local 

 for the Atlantic region, but which seems in Europe to be of 

 unusual importance. 1 



In Great Britain, however, another set of beds, the 

 Tremadoc slates are included in the Cambrian rocks. This 

 group contains many Cambrian types, occurs in the original 

 Cambrian area, and for these reasons is attached to the 

 Cambrian system. The next system begins with the Arenig 

 group in which the true graptolites come in in strength and 

 variety. 



1 Prof. G Lindstrom asserts that in Sweden not a single species passes this 

 limit. 



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