CAMBRIDGE ESSAYS : HOPKINS^ ^'gEOLOGY/' 



517 



Geological Society in 1851, and to the review of it shortly after in the 

 "Quarterly Review." 



The subject will, ho ^^ ever, be better presented to the minds of most 

 of our readers through the medium of general facts. According to 

 existing evidence it appears that invertebrate animals alone existed in 

 the earlier palaeozoic period. Eishes were then introduced and existed 

 in great numbers in the Devonian period; and shortly afterwards 

 reptiles appeared. Small mammals existed in the Middle or Mesozoic 

 period, the whole class becoming completely developed only in the 

 latest geological era. The remains of birds, as might be expected, are 

 comparatively very rare. The introduction of man is the great and 

 final step in this progressive series. 



These facts, and numerous others, are calculated to refute both the ex- 

 treme theories before mentioned — that of the complete development of 

 organic life by successive steps, from the lowest and simplest forms to 

 the highest and most complicated, terminating in man ; and that which 

 maintains that there has been no progression at all. 



But because the proof of one theory is imperfect, we are not there- 

 fore to reject it wholly because of the incompleteness of the proof. 

 We have a large amount of positive evidence in favour of progression j 

 on the other hand, we are not aware of any positive evidence whatever 

 in favour of non-progression, and we are called upon by its advocates 

 to believe it, because future discoveries may supply such evidence. 



Mr. Hopkins now discusses the question, How were new species of 

 animals originally introduced on the face of our globe ? and inclines to 

 the opinion that their introduction was distinct from any progressive 

 transmutation of species according to any actual law of nature, and 

 consequently su2)ernatural. 



Geoffrey St. Hilaire, at the close of the last century, was one of the 

 earliest leaders of the school of transcendental anatomy, as it has been 

 termed. In his views St. Hilaire was directly opposed to the great 

 Cuvier himself, whose labours assuredly laid the foundation of that 

 branch of palieontology which relates to the vertebrata, and which has 

 been since so successfully prosecuted by his successors, and by none 

 more so than our distinguished countryman. Professor Owen. 



With the advance of knowledge of animal organziation, speculative 

 naturalists began to search for generalizations of a higher order than 

 those of mere zoological classification, and many of them adopted the 

 principle of a unity of plan pervading the entire range of animal organ- 

 ization. The poet Goethe was one of the first who entered into these 

 speculative views, which resolved themselves practically into endeavours 

 to discover a form which should serve as a type of all organic forms in 

 the animal kingdom, according to the fundamental notion of a unity of 

 plan, and this object was restricted for a time to the vertebrate skeleton. 

 In the vertebrata the persevering researches of distinguished naturalists 

 have been crowned, it is considered, with success, although they are 

 still far from being agreed as to the precise typical form. That pro- 

 posed by Professor Owen — a naturalist possessed of the boldness of this 

 school of trancendentalists, tempered by the true spirit of induc- 

 tive philosophy — being regarded as having the strongest claims to 

 confidence. 



