60 



zoic epochs, the evidence of vertebrates governing the ocean, and 

 preying on inferior marine vertebrates, is as abundant as that of 

 air-breathing vertebrates in the tertiary strata; but in the one the 

 fossils are exclusively of the cold-blooded reptilian class, in the 

 other, of the warm-blooded mammalian class. The JSnaliosauria, 

 Cetiosauria, and Crocodilia, played the same part and fulfilled 

 similar offices in the seas from which the lias and oolites were 

 precipitated, as the Delphinidce and Balcenidce did in the tertiary, 

 and still do in the. present, seas. The unbiassed conclusion from 

 both negative and positive evidence in this matter is, that the 

 Cetacea succeeded and superseded the Enaliosauria. To the mind 

 that will not accept such conclusion, the stratified oolitic rocks 

 must cease to be monuments or trustworthy records of the con- 

 dition of life on the earth at that period. 



So far, however, as any general conclusion can be deduced from 

 the large sum of evidence above referred to, and contrasted, it is 

 against the doctrine of the Uniformitarian. Organic remains, 

 traced from their earliest known graves, are succeeded, one series by 

 another, to the present period, and never re-appear when once lost 

 sight of in the ascending search. As well might we expect a 

 living Ichthyosaur in the Pacific, as a fossil whale in the Lias : the 

 rule governs as strongly in the retrospect as the prospect. And 

 not only as respects the Vertebrata, but the sum of the animal 

 species at each successive geological period has been distinct and 

 peculiar to such period. 



Not that the extinction of such forms or species was sudden or 

 simultaneous : the evidences so interpreted have been but local : 

 over the wider field of life at any given epoch, the change has been 

 gradual ; and, as it would, seem, obedient to some general, but as 

 yet, ill-comprehended law. In regard to animal life, and its as- 

 signed work on this planet, there has, however, plainly been ' an 

 ascent and progress in the main/ 



Although the mammalia, in regard to the plenary development 

 of the characteristic orders, belong to the Tertiary division of geo- 

 logical time, just as 'Echini are most common in the superior 

 strata, Ammonites in those beneath, and Producti with numerous 

 Encrini in the lowest' 1 of the secondary strata, yet the beginnings 

 of the class manifest themselves in the formations of the earlier 

 preceding division of geological time. 



No one, save a prepossessed Uniformitarian, would infer from 

 1 A generalisation of WILLIAM SMITH'S. 



