REPORT OF THE STATE PALEONTOLOGIST 1902 



947 



In combining all the facts, viz that the underlying Dolgelly 

 beds contain well known European and also eastern American 

 Upper Cambric horizon markers, such asPeltura scara- 

 baeoides, and the overlying Tremadoc terrane as distinctly 

 Lower Siiuric forms such as Calymmene blumen- 

 b a c h i i, while the graptolites, on account of their pelagic life, 

 have a wide horizontal and very limited vertical distribution and 

 are themselves extremely exact indicators of synchrony, we be- 

 lieve it does not infringe on the rights of British geologists to 

 conclude that the Dictyonema flabelliforme zone 

 is in Britain as in the rest of Europe to be held as marking the 

 top of the Cambric series, wherever it is observed. 



The Dictyonema bed in North America 



The first to publish a notice on the occurrence of the Dictyo- 

 nema bed in America was, so far as we know, Sir William 

 Dawson. 1 Sir William reports that Mr Richardson found at 

 Matane " a bed of highly laminated black shale similar to that 

 explored by Mr Weston a few years ago at Little White river, 

 holding similar fossils in great abundance. Prominent among 

 them is a beautiful Dictyonema, distinct from any of these found 

 at Levis, and which on comparison with specimens presented 

 to the museum by Prof. H. Alleyne Nicholson, appears so 

 close in all its characters to D. s o c i a 1 e Salter, of the Eng- 

 lish Tremadoc, that it may fairly be assumed to represent that 

 species in our fauna. It is well known that some good paleon- 

 tologists regard D. s o c i a 1 e as only varietally distinct from 

 D. flabelliforme pf Eichwald from Russia. . . We 

 might infer from this that the Dictyonema beds at Matane may 

 indicate a horizon somewhat lower than any of those at Levis. 

 Associated with the Dictyonema are many specimens of 

 Dichograptus (corrected in handwriting for Didymograp- 

 tus) flexilis and D. 1 o g a n i, or an allied form, and 

 there are also fragments of an undetermined Tetragraptus." 2 



1 Peter Redpath Mus. of MacGill Univ. 2d Rep. Jan. 1883: p. 16. 

 ' We have no doubt that the species of Dichograptus cited here refer to the 

 Cambric species of Clonograptus, either to C 1 . proximat us Matthew or 

 CI. m i 1 e s i Hall, specially as also elsewhere these Cambric Clonograpti 

 have been first compared with the Beekmantown Clonograptus 

 Dichograptus) flexilis. 



