12 . THE CANADIAN NATURALIST. [Vol. ix. 



"were merely incidentally noticed, but I know that he regretted 

 the error very much, though of course as I had, eight or nine 

 years before, abandoned u\\ idea of these rocks being Devonian, I 

 €Ould not be blamed for it. 



Another point raised in the paper now in question, is the use 

 of the terms Upper Arisaig and Lowe?- Arisaig, a point perhaps 

 of no great geological importance, but of some consequence since 

 the abuse of those names has tended to cause confusion. Dr. H. 

 calls this a " new division introduced in the second edition of the 

 Acadian Geology, 1868," but it was really introduced in my 

 paper of 1859 above quoted, and this Dr. H. has himself ad- 

 mitted in the Journal of the Geological Society, vol. xx, p. 233, 

 though it seems now to have escaped his memory. The reasons 

 for this division were as follows. The term "Arisaig series" is 

 a useful local name for the peculiar development of the Upper 

 Silurian in Eastern Nova Scotia. The results of Prof Hall 

 showed that the fossils were referable to the Clinton and Lower 

 Helderberg, without the intervention of any distiuct representa- 

 tive of the Niagara limestone, and as the lower and upper mem- 

 bers were somewhat distinct in mineral character, it seemed the 

 most natural course to divide the series into Lower and Upper. 

 Dr. H., who had an opportunity of showing his fossils to the 

 late eminent palaeontologist Mr. Salter, gives on his authority a 

 more minute subdivision into five members. This will be found 

 discussed in Acadian Geology, I trust in a fair spirit, and the 

 relations of the two arrangements pointed out. But more recently 

 Dr. H. has thought proper to change the name of the whole Ari- 

 saig series as before understood, to "Upper Arisaig," and to in- 

 clude as " Lower Arisaig" rocks which he regards as Laurentian. 

 This is objectionable, not only as interfering with established 

 and useful names, but as extending local terms to a degree which 

 no other geologist can possibly accept. It amounts in fact to 

 calling the whole Eozoic and Lower Palaeozoic by the local name 

 " Arisaiu; series." For these reasons I shall continue, as hereto- 

 fore, to use the terms Upper and Lower Arisaig for the subdivi- 

 sions of the Upper Silurian as represented at that place. 



Another question raised in this paper relates to certain 

 rocks at Lochaber, in which Dr. H. affirms that he found fossils 

 of the oenus Fetraia, which I had informed him belonged to the 

 genus Zaphreiitis, and thereby misled him as to their age. The 

 specimens referred to were sent to Montreal in 1860, along with 



