80 



in Newfoundland and the Paradoxides beds rear Boston are, in all 

 probability, of the same age. We have not yet discovered this fauna in 

 Canada. 



Judging from the aspect of the fossils I should say that what we call 

 Potsdam group is more recent, but next in succession. It consists of two 

 or tliree divisions. The lowest of these appears to be the sandstones and 

 limestones on the north shore of the straits of Belleisle, and the rocks 

 which, in the state of Vermont, are called the Georgia slates and the Red 

 sand-rock. These are characterized by Olenellns Vermonfana, 0. Tliomp- 

 soni, (Jonoeephalites Adamsi, C. Teucer, C. Vidcanus, 0. arenosus, Ba- 

 thi/urus senectus, B. parvulus, Salterella rugosa, S. pulchella, S. ohtusa, 

 Obolus Labradoricus , Oholella cTiromatica, 0. QKutorgina) clngulata, 

 Orthisina festinata, Oamerella antiquata. Archeocyathus Atlanticus, A. 

 profundus, Scolithus linearis, Palaeophyeus incipiens, and P. congregatus, 

 with several other obscure forms of similar types. This fauna is totally 

 distinct from that of the New Brunswick Lingula Flags, the St. John's 

 group of Mr. Matthew. It might be called the Lower Potsdam. 



We have next the Potsdam sandstone of Wisconsin and Minnesota hold- 

 ing so far as is yet known, about 50 species, mostly trilobites of a primor- 

 dial type. There is some evidence to show that the upper part of the 

 typical Potsdam of Canada and New York is of the same age. In these 

 rocks Gasteropoda and Cephalopoda first make their appearance, although 

 they are rare and the species small. The fauna is entirely distinct from 

 those of the St. John's group and Lower Potsdam. It seems probable that 

 the Lower and Upper Potsdam correspond to the Upper Lingula Flags, but 

 this correlation cannot be clearly proved by the fossils as yet. 



Next in succession comes the Lower Calciferous of Canada, New York, 

 and Newfoundland. This is the original Calciferous sandrock of the New 

 York survey. In this formation there are known to me nearly 150 spe- 

 cies of fossils, about 100 of which are described. They are all with one 

 exception (^Pleurotomaria Canadensis') distinct from those of the Upper 

 Potsdam. Gasteropoda and Cephalopoda become numerous, and Lamel- 

 libranchiata first appear rarely. This formation has been identified in 

 Scotland by Sir R. I. Murchison and Mr. Salter, in the Durness lime- 

 stone, but it has not yet been determined to what particular horizon in 

 ihe English series ihe limestone in question belongs. 



The Upper Calciferous has not yet been discovered in either Canada or 

 New York. It has only been observed in Newfoundland where it is over 

 1000 feet in thickness, but has yielded as yet, only about 40 species of 

 fossils. A few of these are found in the Lower Calciferous, and several 

 pass upwards. This formation corresponds to divisions I. K. L. M., of 

 the Newfoundland rocks described in the Geology of Canada, and also in 

 my Palseozoic Fossils, Vol. 1. 



