262 PICTURESQUE SKETCHES 



in such relative numerical abundance, as to render 

 it probable that the apparent absence of animals of 

 higher organization is not accidental, or a conclusion 

 based on imperfect examination, but that it was real 

 and absolute. 



The corresponding* characteristic of the former and 

 earlier period we found to be the great development 

 of fishes, which occupied then the position afterwards 

 filled by reptiles. Now it is this apparent substitu- 

 tion or representation that gives confidence and jus- 

 tifies the conclusions drawn. By the help of compa- 

 rative views of this kind, we perceive the meaning, 

 the symmetry, and the perfectness of each group, and 

 the adaptation of each to its own end. By carefully 

 carrying out the method of comparison, we gradually 

 attain more distinct, less exaggerated, and more ra- 

 tional views of the differences of organic being at 

 various periods ; and there is no doubt that the views 

 thus attained are infinitely more real than those de- 

 rived from the examination of a few isolated facts of 

 marvellous character, which attract the imagination, 

 but which for that very reason are likely to mislead 

 the judgment. 



If called upon to give a general account of the phy- 

 sical geography of the secondary period, in the vici- 

 nity of our own island, I might venture to suggest, 

 1. That during this period there were many in- 

 considerable disturbances of the bed of an ocean which 

 then covered our island, but which was partially 

 bounded in several directions by islands extending to 

 the west and north, the lines of coast being more or 

 less extensive, and generally at no great distance. 

 2. That the effect of these disturbances was for a 



