REPORT OF THE STATE PALEONTOLOGIST 1902 943 



It is further stated, that, while to some degree the Niobe- 

 Euloma fauna has still a mixed character, and contains primor- 

 dial forms (specially Olenidae), the typically developed fauna of 

 the Ceratopyge shale and still more of the Ceratopyge limestone 

 in Norway is in most prevailing degree a Lower Siluric fauna. 



Freeh states that not a single species of trilobites goes beyond 

 the Dictyonema shale into the Ceratopyge limestone in Sweden, 

 in Norway Cyclognathus micropygus passes still 

 into the Symphysurus bed, but not into the Ceratopyge shale; 

 while, on the other hand, there appear not less than three new 

 families and 13 genera above the Dictyonema bed. Therefore 

 Brogger's claim appears fully justified: 



The northern paleontologists, almost without exception, have 

 always agreed to place the termination of the primordial fauna 

 at the Dictyograptus slate; thus have done Linnarsson, Lind- 

 strom, Nathorst, Tullberg, Holm, Lundgren, etc. in Sweden; that 

 have T done similarly for Norway. 



If one therefore will use the term " Cambrium " for the pri- 

 mordial-siluric sediments . . . then in my view one must 

 also in England, Wales, France, America, etc., if this term shall 

 be defined reasonably, put the upper limit of the Cambrium there 

 where the second, to use Lapworth's name, the Ordovicic fauna be- 

 gins, i. e. immediately above the Dictyograptus slate. 



The Cambric of the Baltic provinces of Russia has been thor- 

 oughly investigated by Fr. Schmidt. 1 It shows considerable 

 modification from the typical development in southern Sweden. 

 The black shales so characteristic in Scandinavia have thinned 

 out, and soft and seemingly not very old deposits appear in 

 their place. It is divided by Schmidt into three stages, (1) the 

 Blue clay, (2) the Ungulite grit, and (3) the Dictyonema slates, 

 which form the characteristic uppermost zone of the system. 

 Of this it is said : 



This, stage (3), the Dictyonema slate, is the highest member 

 of our Cambrian series, and a very important one too, as it is 

 the only indubitable connecting link between our Cambrian 

 and that of Scandinavia. The Dictyonema slate has a thickness 

 of from 1 to 10 feet and is exactly identical with the same stage 

 as developed in Sweden and Norway. 



1 Geol. Soc. Quar. Jour. Nov. 1882, p. 516; Acad. Imp. Sci. St Petersburg. 

 Mem. 2. 1889. v. 36. 



