9B ROYAL SOCIETY OF CANADA 



are the most easily uvailablo as geological chronoineters, and have been 

 80 used both in Europe and America ; but they do not accurately repre- 

 sent the series of changes going on in the great oceanic areas and their 

 margins. 



Viewed in this way, Logan's name, Quebec Group, designates the 

 oceanic deposits formed on the Atlantic border of North America at a 

 time when very different conditions prevailed in those now inland areas 

 which atforded the classification of the Xew York Survey. The fact of 

 this great difference remains, and the term designating it will continue to 

 be of value to geologists, so long as they are desirous rationally to corre- 

 late the sequence of formations in America and in Europe, and to connect 

 with their science those great facts of paUeogeography which enable us 

 to realize the diverse conditions of the depressed and elevated portions of 

 the earth's surface in different geological times. The name is farther 

 justiffed by the fact that the lower portions of our great St. Lawrence 

 river follow a course in the Province of Quebec which enables them bet- 

 ter than any other section in America to illustrate the difference between 

 the deposits of the Atlantic and continental areas in the early Pahcozoic 

 period. 



I regard these considerations as of great importance in relation to 

 the fossils described in this paper, becau.se they are members of a fauna 

 of almost universal oceanic distribution ; in its time extending continu- 

 ously over vast spaces and periods, and serving to bridge over the gaps 

 in the broken series of the continental i^lateaus. It is likely to gain in 

 significance and in relative value as science advances; and, when more 

 fully known and appreciated, to do much toward remedying that imper- 

 fection of our geological record, which depends, to some extent, on our 

 basing it on localities where physical distui-bances have interfered with 

 the continuity and orderly succession of life. It is only by the patient 

 and long-continued study of the formations deposited on those parts of 

 the permanent oceanic areas available to us, that we shall ultimately be 

 able to trace back the marine life discovered by the dredgings of the 

 •' Challenger," to early geological times. ' v ' 



When Logan commenced his survey of Canada in 1842, little of this 

 was understood, and he had before him the task of solving the enigma of 

 original differences of deposits and superadded mechanical disturbances in 

 Eastern Canada, with the wholly inadequate key afforded by the inland 

 aeries of formations worked out by the survey of New York, which itself, 

 when it came into contact with the marginal series, became involved 

 in that Tacouic controversy, which hils scarcely yet subsided, and which 

 must remain in some degree unsettled as long as geologists fail to see that 

 they cannot force into one system the dissimilar formations of the ocean 

 and of the continental plateaus. I have no wish here to dwell on these 

 controversies ; but may refer for some statement of my views on the great 



