ANNIVEESAEY ADDEESS OF THE TEESIDENT. XXXli 



the problems we examine and the conclusions we adopt. That better 

 knowledge may lead wise and benevolent friends of science to favour 

 our branch of useful knowledge by scholarships and fellowships, to be 

 won by conspicuous merit at our universities, and employed for the 

 benefit of our country in the field, in the senate, and the pulpit. If 

 our data be not sufficient, if our reasoning be not right, the more 

 thankful should we be to the friendly sceptic who puts us to the 

 proof. 



An objection to the cogency of our conclusions in regard to tho 

 history of the changes which the surface of the earth has undcrgono 

 is founded on the incompleteness of the record which we find in the 

 organic remains. It is incomplete, in some departments more than 

 in others ; but we must not admit it to be insufficient to sustain just 

 conclusions ; for these cannot extend bc3"ond the data. 



The main subject of the record by fossils is the history of the sea 

 and its bed ; and for this the data appear sufficient. They are 

 incomplete in regard to fresh water, the land, and the air, and 

 must ever remain so. It is only by the intercalation of reliquiae 

 derived from these, in the series of marine deposits, that we can assign 

 to them their right date ; and the occurrence of land and freshwater 

 remains among marine deposits is, and must always have been, com- 

 paratively rare, and, with reference to tho history of the ocean, 

 almost accidental. 



Still we must not undervalue the evidence thus afforded. The coal- 

 deposits give us considerable information of the plants of one period, 

 naturally growing and gathered together on the edge of the sea ; from 

 the trias, the oolitic coal-fields, the wealden and cretaceous deposits, 

 avc obtain a large and varied flora of the Mcsozoic period ; and many 

 of the tertiary strata yield quite different groups of the later vegeta- 

 tions. Among the coal-deposits lie skeletons of several reptiles *, a 

 few land and freshwater shells and articulataf ; among the oolitic 

 shore- and river-sediments lie mammalia, with many reptiles which 

 lived on the land, or in fresh waters, or traversed the air ; and 

 in the tertiary group of strata the remains of all the vertebrated 

 classes, including lacustrine and terrestrial nves, occur in abundant 9. 

 [f we cannot thus reconstruct the whole animal and vegetable king- 

 dom, we have numerous and instructive examples of both at certain 

 important epochs in the three great geological periods. 



To judge of the completeness with which individual groups aro 

 preserved to represent the whole series of that particular life, we 

 may select some very distinct marine genera rich in species. Such 

 occur among the Brachiopoda, Conchifera, and Cephalopoda. Pi c 

 example, Terebratuila, possibly absent from all the Silurians, shows 

 itself frequently in the Devonian, Carboniferous, and Permian strata; 

 abundantly in the Lias, Oolites, and Cretaceous recks; but sparingly 

 in the Tertiary beds and in modern oceans. In this extensive series, 

 tho shells of the genus retain always the characteristic tubules, the 



* Archegosaarut in Europe, Dmdrtrpeton and Hylonomut in Nora Scotia. 



t Some recently found iu the co.il-ili ipoflil 9 uli;i by Dr. Dawson, 



besides the hueota of the English and European cual-Ud.-. 



