74 THEORY OP THE EARTH. 



exists, or to one that is now lost. As, on the other 

 hand, we are still very far from being acquainted 

 with all the testaceous animals and fishes belong- 

 ing to the sea, and as we probably still remain ig- 

 norant of the greater part of those which live in 

 the extensive deeps of the ocean, it is impossible 

 to know, with any certainty, whether a species 

 found in a fossil state may not still exist somewhere 

 alive. Hence some naturalists persist in giving 

 the name of oceanic or pelagic shells to belemnites 

 and cornua-ammonis, and some other genera, which 

 have not hitherto been found, except in the fossil 

 state, in ancient strata; meaning by this, that al- 

 though these have not as yet been found in a living 

 or recent state, it is because they inhabit the bot- 

 tom of the ocean, far beyond the reach of our nets. 



25. Of the small Probability of discovering new Spe- 

 cies of the larger Quadrupeds. 



Naturalists certainly have neither explored all 

 the continents, nor do they as yet know even all 

 the quadrupeds of those parts which have been 

 explored. New species of this class are discover- 

 ed from time to time ; and those who have not ex- 

 amined with attention all the circumstances be- 

 longing to these discoveries, may allege also, that 

 the unknown quadrupeds, whose fossil bones have 

 been found in the strata of the earth, have hitherto 

 remained concealed in some islands not yet dis- 

 covered by navigators, or in some of the vast de- 





