HONEYMAN ON NOVA SCOTIAN GEOLOGY, 391 



At Arlsalg the Mayhill sandstone of Salter occupies the lowest 

 position in the Series, and it has the same relative position in the 

 several localities where it occurs in Nova Scotia. Its characteristic 

 fauna is perfectly distinct from that of the others. Its lithology 

 is also peculiar. While the other fossiliferous strata of the group 

 are argillaceous this is highly siliceous — parts are simply sandstone. 

 In one locality the strata are siliceous and the contained fossils 

 are silicified casts. I have no difficulty whatever in recognizing the 

 Mayhill sandstone strata from their relative position and lithology, 

 when I find them, and the characteristic fossils appear as a matter 

 of course. In previous papers I have given my reasons for distin- 

 guishing B. and B'. into Lower and Upper Clinton. I have 

 followed the example of Hall in dividing the Arisaig Series into 

 Middle and Upper Silurian. I have also been in the habit of 

 correlating it thus : 



England. United States. 



A. Mayhill Sandstone Medina Sandstone. 



B. Lower Clinton. 



B.' Upper Clinton. 



C. Aymestry Limestone Niagara Limestone. 



D. Upper Ludlow Lower Helderberg. 



A. B. B' Middle Silurian. 



C. D Upper Silurian. 



In correlating the Arisaig Series with the United States divi- 

 sions. I have found it difficult to correlate D. with the Lower 

 Helderberg, notwithstanding that I had access to the best American 

 authorities, and lists of figures. I am not surprised that Hall and 

 others regarded the fauna of D. as Devonian, as they appear to 

 have a greater resemblance to the Hamilton and Chemung than to 

 the Lower Helderberg. The fades of the fauna of D. is strongly 

 English, I experienced no difficulty in recognizing it in the Upper 

 Ludlow of Murchison^s Siluria. I believe that it is only through 

 England that it can be correlated with the Lower Helderberg of 

 the United States. C. is easily correlated with the Niagara lime- 

 stone of the United States. B'. is with common consent admitted 

 to be of Clinton age. United States. I have designated B. Lower 

 Clinton, for reasons already given. I have not been able to correlate 



