6 A Period in the Jlistori/ of our Planet, 



same one-sided apprehension of facts, as the view which dis- 

 cerns, in our present creation, a repetition of these attempts, 

 and assumes a scale which the idea of the perfect organism is to 

 ascend, in order to be finally developed in man in its fullest 

 blossom. There can be no doubt, that a polypus, or a worm, 

 is more imperfectly organized than a mammiferous animal, or 

 man, — more imperfect on principle ; but does it follow from 

 that, that these creatures are more imperfectly organized for 

 the situation to which they are destined 1 Is man a more 

 perfect being in the water, than a fish is in the air ? Cer- 

 tainly not. 



And what is applicable to the gradual development of the 

 idea of the perfect organism in our present creation, taken 

 collectively, can also be shewn to be applicable to the de- 

 velopment of the same, through the gradations of the geologi- 

 cal epochs. 



If we must admit that the organisms of the greywacke, 

 viewed as a whole, are more imperfect than those of the Jura 

 formation, and the latter again more imperfect than those of the 

 tertiary period, so, on the other hand, we must not lose sight 

 of the fact that they correspond most exactly to the circum- 

 stances under which they lived, and that they were just as per- 

 fect under those circumstances as our present creation is in 

 the present epoch. "Would it have been a better adaptation 

 to have placed men upon the narrow islands of the Jurassic 

 ocean, instead of those uncouth reptiles which peopled its 

 shores ? Or ought the clumsy pachydermata, which grubbed 

 through the morasses of the tertiary period, to have swam 

 about in the hot seas of the greywacke ? 



Let us endeavour to give, in a few sketches, a view of the 

 more ancient epochs of the earth"'s history, in order to arrive, 

 in the simplest manner, at what is to form the immediate 

 subject of our inquiry. 



We cannot here attempt any thing like a detailed view 

 of the formations with which geology makes us acquaint- 

 ed ; we can only indicate by a few rough strokes the prin- 

 cipal points in the grand picture of the earth's history. 

 There can, therefore, be no such thing as any very strict geo- 

 logical sifting. I here unite, as one formation, the first periods 



