FUNDAMENTAL RELATIONS OF ANIMALS 29 



a successive introduction of tliese types upon earth is flatly contra- 

 dicted by well established and well known facts.^^ Moreover, the re- 

 mains found in the oldest deposits are everywhere closely allied to 

 one another. In Russia, in Sweden, in Bohemia, and in various other 

 parts of the world, where these oldest formations have been altered 

 upon a more or less extensive scale, as well as in North America, 

 where they have undergone little or no change, they present the same 

 general character, that close correspondence in their structure and in 

 the combination of their families, which shows them to have belonged 

 to contemporaneous fauna?. It would, therefore, seem that even where 

 metamorphic rocks prevail, the traces of the earliest inhabitants of 

 this globe have not been entirely obliterated. 



SECTION VIII 

 THE GRADATION OF STRUCTURE AMONG ANIMALS 



There is not only variety among animals and plants; they differ 

 also as to their standing, their rank, their superiority or inferiority 

 when compared to one another. But this rank is difficult to deter- 

 mine; for while in some respects all animals are equally perfect, as 

 they perform completely the part assigned to them in the general 

 economy of nature,^^ in other respects there are such striking differ- 

 ences between them, that their very agreement in certain features 

 points at their superiority or inferiority in regard to others. 



This being the case, the question first arises. Do all animals form 

 one unbroken series from the lowest to the highest? Before the animal 

 kingdom had been studied so closely as it has been of late, many 

 able writers really believed that all animals formed but one simple 

 continuous series, the gradation of which Bonnet has been particu- 

 larly industrious in trying to ascertain.^^ At a later period Lamarck^*' 



^ Agassiz, "The Primitive Diversity and Number of Animals in Geological Times," 



American Journal of Science, XVII (2d ser., 1854), 309-354. 



^ Christian Ehrenberg, Das Naturreich des Menschen, oder das Reich der willens- 

 peien beseelten Naturkorper, in 29 Classen ilbersichtUch geordnet (Berlin, 1835, folio, 

 1 sheet). 



^° Charles Bonnet, Considerations sur les corps organises (2 vols., .Amsterdam, 1762); 

 Contemplations de la nature (2 vols., Amsterdam, 1764-1765); Palingenesie philoso- 

 phique (2 vols., Geneva, 1769). 



^^ Philosophie zoologique (1809). 



