No. 1.] DAWSON — GEOLOGY OF NOVA SCOTIA. 5 



fcssiliferous slates and coarse arenaceous limestone, and a bed of 

 gray sandstone with numerous indistinct impressions apparently 

 of plants. In addition to several of the fossils found atNictaux, 

 these beds afford Tentaculites^ an Atrypa, apparently identical 

 with an undescribed species very characteristic of the Devonian 

 sandstones of Gaspe [this is now known as Leptocoelia JiabelHtes]^ 

 and a coral which Mr. Billings identifies with the Pleurodicfji/um 

 prohlematicum, Goldfuss, a form which occurs in the Lower De- 

 vonian in England, and on the continent of Europe." 



It will thus be seen that I recognized, on the evidence of strati- 

 graphy and fossils, in the district extending from New Canaan 

 to Bear River, the following groups of rocks : — 



1. The Niagara series, the Wenlock of English geologists, re- 

 presented by the Dictyouema shales and the coral-bearing rocks 

 of New Canaan. This group may be called either Middle or 

 Upper Silurian, according to different classifications in use. 



2. The Upper Arisaig series (of my arrangement, not of that 

 subsequently advocated by Dr. H.) This is the equivalent of 

 the Lower Helderberg series of America, the Ludlow of England, 

 and is the upper member of the Upper Silurian as held at that 

 time. 



3. The Oribkany series, represented by iron ores, sandstones 

 or slates. At that time the Oriskany was regarded by all as 

 Lower Devonian. More recently some American geologists have 

 proposed to place it in the upper part of the Upper Silurian, 

 above the Lower Helderberg, with which its fossils have some 

 afl&nity. 



If I understand Dr. H,, he admits the ages which I have 

 assigned to Nos. 1 and 2 above mentioned, though, after his usual 

 manner, without giving the slightest credit for the original dis- 

 covery of the facts, but he assigns No. 3 to the horizon of the 

 Medina sandstone, a formation older than the Niagara, and re- 

 garded as an equivalent of the Mayhill sandstone (Llandovery) 

 of Great Britain. The first reason assigned for this opinion is 

 one based on mineral character, "I at once recognized the May- 

 hill sandstone," &c. On this I may merely remark that any 

 geologist who would profess to distinguish at sight the Oriskany 

 sandstone from the Medina sandstone would be more character- 

 ised by boldness than prudence. The stratigraphy of the district 

 is confessedly somewhat obscure, and I fail to find in Dr. H.'s 

 paper any new light tending to the inversion of the section as it 



