206 Agami Contributions to the 



globe, has naturally led to the very general belief, that the ani- 

 mals which have existed during the earliest period of the history 

 of our earth were inferior to those now living, nay, that there is 

 a natural gradation from the oldest and lowest animals to the 

 highest now in existence. To some extent this is true ; but it is 

 certainly not true that all animals form one simple series from 

 the earliest times, during which only the lowest types of animals 

 would have been represented, to the last period, when Man ap- 

 peared at the head of the animal creation. It has already been 

 shown (Sect. VII.) that representatives of all the great types of 

 the animal kingdom have existed from the beginning of the crea- 

 tion of organized beings. It is therefore not in the successive 

 appearance of the great branches of the animal kingdom, that we 

 may expect to trace a parallelism between their succession in 

 geological times and their relative standing at present. Nor can 

 any such correspondence be observed between the appearance of 

 classes, at least not among Radiata, Mollusks, and Articulata, as 

 their respective classes seem to have been introduced simultane- 

 ously upon our earth, with perhaps the sole exception of the In- 

 sects, which are not known to have existed before the Carboni- 

 ferous period. Among Vertebrata, however, there appears al- 

 ready a certain coincidence, even within the limits of the classes, 

 between the time of their introduction, and the rank their repre- 

 sentatives hold, in comparison to one another. But upon this 

 point more hereafter. 



It is only within the limits of the different orders of each class, 

 that the parallelism between the succession of their representa- 

 tives in past ages and their respective rank, in the present period? 

 is decidedly characteristic. But if this is true, it must be at the 

 same time obvious to what extent the recognition of this corres- 

 pondence may be influenced by the state of our knowledge of the 

 true affinities and natural gradation of living animals, and that 

 until our classifications have become the correct expression of 

 these natural relations, even the most striking coincidence with 

 the succession of their representatives in past ages may be entire- 

 ly overlooked. On that account it would be presumptuous on 

 my part to pretend, that I could illustrate this proposition, through 

 the whole animal kingdom, as such an attempt would involve 

 the assertion that I know all these relations, or that where there 

 exists a discrepancy between the classification and the succession 

 of animals, the classification must be incorrect, or the relationship 



