522 FOSSIL INVERTEBRATED ANIMALS. 



depth, yet they presumed not only to speculate, but to dogma- 

 tize, respecting the origin and formation of the planet itself. 

 But subsequent geologists have abandoned the ignis fatuus of 

 hypothesis for the steady light of observation ; and by an indus- 

 trious accumulation of facts, united with the most salutary 

 cautiousness of deduction, have laid a safe and just foundation 

 for the science. By following in their footsteps, geological 

 speculations cannot fail to assume more and more a character 

 of greater certainty ; and as we can set no limits to the sources 

 of power which futurity may disclose, we may indulge the hope 

 that a " theory of the earth " may be yet established, on a 

 firmer basis than the air-built edifices of former world-makers. 

 That such a hope is not altogether chimerical, we are warranted 

 in believing, by the rapid strides made, within but a few years, 

 in the practical application of scientific principles. Time has 

 already realized much that the most enthusiastic votaries of 

 science scarcely dared to dream of; and it may realize so much 

 more, that our posterity may one day have occasion to ex- 

 claim — 



*• Quod optanti Divum proraittere nemo 

 Auderet, volvenda dies en attulit ultro." 



