140 Canadian Record of Science. 



rest upon primary (that is crystalline) rocks." Thus his 

 Taconic of 1855 is clearly the Middle and Lower Cambrian 

 of modern geologists, and the fossils which he attributes to 

 the Taconic, are in great part of this age. That in the 

 subsequent pages of his book, in tracing the Taconic 

 through the complex structure of the districts in which it 

 occurs, and enumerating its fossils, he mixes other forma- 

 tions with it is most true. But fair critics of Emmons 

 would do well to eliminate these errors, and leave him the 

 credit of his discoveries in those pre-Potsdam rocks, which, 

 though different in age from the Quebec group, are like it, 

 in the main a marginal Atlantic series, not represented in 

 the central plateau. 



I do not wish, however, to enter into the " Taconic con- 

 troversy," or to discuss the utility of now reviving Emmons' 

 name, but merely to mention the points in which it re- 

 sembles and differs from that of Logan, which belongs to a 

 different series, and to which it has in many respects 

 inferior claims. 



I may sum up the matter by quoting a few sentences 

 from one of the papers above referred to: — " The researches 

 of Sir William, with those of Dr. Sterry Hunt and Professor 

 Hall and Mr. Billings, have sufficed to demonstrate — 1. 

 The general diversity of mineral character in the Palaeozoic 

 sediments on the Atlantic slope as compared with the in- 

 ternal plateau of* Canada. In these results Bailey, Matthew 

 and Hartt in New Brunswick, and the writer in Nova 

 Scotia, have also borne some part. 2. The establishment 

 of the Quebec group of rocks as a series equivalent in age 

 to the Calciferous-chazy of America, west of the Apala- 

 chian mountains, and to the Arenig and Skiddaw of 

 England, and the elucidation of its special fauna, 3. The 

 tracing out and definition of the peculiar faulted junction 

 of the coastal series with that of the interior plateau, exten- 

 ding from Quebec to Lake Champlain. 4. The definition 

 in connection with the rocks of the Quebec group, by fossils 

 and stratigraphy, of formations extending in age from the 

 Potsdam sandstone to the Upper Silurian, as in contact with 



