406 THE CANADIAN NATURALIST. [Vol. vi. 



It cannot be assumed that the fauna of the older part of the 

 Canadian Post-pliocene is different to any great extent from that 

 of the more modern part. Such difference as exists seems to 

 depend merely on a gradual amelioration of climate. The shells 

 of the lower Boulder clay, and of those more inland and elevated 

 portions of the beds which may be regarded as older than those 

 of the lower terraces near the coast, are undoubtedly more Arctic 

 in character. The amelioration of the climate seems to have 

 kept pace with the gradual elevation of the land, which threw 

 the cold ice-bearing Arctic currents from its surface, and exposed 

 a larger area of land to the action of solar heat, and also probably 

 determined the flow of the waters of the Gulf Stream into the 

 North Atlantic. By these causes the summer heat was increased, 

 the winds both from the land and sea were raised in temperature, 

 and the heavy northern ice was led out into the Atlantic, to be 

 melted by the Gulf Stream, instead of being drifted to the south- 

 west over the lower levels of the continent. vStill the cold Arctic 

 currents entering by the Straits of Belle-isle and the accumula- 

 tion of ice and snow in winter, are sufficient to enable the old 

 Arctic fauna to maintain itself on the Northern side of the Gulf 

 of St. Lawrence, and to extend as far as the latitudes of Murray 

 Bay and Gaspe. South of Gasp^ we have the warmer New 

 England fauna of Northumberland Strait. I may add that some 

 of the peculiarities of the Post-pliocene fauna in comparison with 

 that of the St. Lawrence river, indicate a considerable influx of 

 fresh water, derived possibly from melting ice and snow. 



PART III. — GENERAL CONCLUSIONS. 



This Memoir has already extended to so great length, that I 

 shall be under the necessity of dwelling as little as possible on 

 the general geological truths deducible from the facts which 

 have been stated. I shall specially refer to only two points : 

 (1) The relation of the Post-pliocene fossils to questions of 

 derivation of species ; (2) The bearing of the facts above stated 

 on theories of land glaciation. 



On the first of these subjects I may remark that whatever may 

 have been the lapse of geological time from the period of the 

 oldest Boulder Clay to that in which we live, and great though 

 the climatal and geographical changes have been, we cannot 

 affirm that any change even of varietal value has taken place in 



