No. 3.] NATURAL HISTORY SOCIETY. 177 



the hope that the age assigned to them may be indicated by 

 fossils, while, if like some similar beds to the southward, they 

 hold Silurian species, these also must in some places be recog- 

 nizable ; so that if they finally fail to afford fossil remains or 

 yield Lower Cambrian species, this, with their mineral character 

 and apparent distribution, would sustain Mr. Selwyn's view ; 

 while, on the other hand, the discovery of a few distinctive Silu- 

 rian forms might suffice to overturn it. 



It would appear that the third and second series of Mr. Sel- 

 wyn, above mentioned, are the same with the rocks which in 

 Hitchcock's map of New Hampshire are named Montalban and 

 Huronian. The former term has however been applied by Dr. 

 Hunt to a series newer than the Huronian, and possibly of Lower 

 Cambrian age, so that if it is correctly used by Hitchcock, his 

 so-called Huronian may be in reality Upper Cambrian or Lower 

 Silurian. It is to be deprecated as not conducive to correct 

 conclusions, that terms of this kind should be used to represent 

 merely mineral resemblances, irrespective of those evidences of 

 geological age derived from stratigraphy and fossils. It is due 

 here to Dr. Hunt to explain that he has for many years on inde- 

 pendent grounds regarded the beds of Mr. Selwyn's second and 

 third groups as, for the most part at least, Huronian in ago. and 

 a similar conclusion was also arrived at from comparison with 

 the older formations of Scandinavia, by Mr. Macfarlane. Thus 

 in one way or another all these gentlemen dissent from Sir 

 William's conclusions, while also differing from each other, a 

 sufficient evidence of the complicated character of the problem 

 with which he had to deal, and whose ultimate solution may em- 

 brace elements of all the generalizations which have been put 

 forth. 



Some suggestions may at least be offered toward the solution 

 of these questions which deserve the attention of those who have 

 been occupied with them. The first is that we should accustom 

 ourselves to the anticipation that contemporaneous palagozoic 

 rocks in the regions of the western lakes, of the plains of Ontario 

 and Quebec, and of the eastern slope, are not likely to be iden- 

 tical in mineral character. Farther, that even in the central of 

 these three regions we may expect differences in approaching 

 certain parts of the older rocks. At Murray Bay, for example, 

 on the border of the Laurentian, we find the Black River 

 limestones in great part represented by coarse sandstones, and we 

 Vol. IX. M No. 3. 



