Professor Pictet on the Distribution of Fossils. 271 



of inferior animals. It is itself divisible into four other 

 types of unequal perfection in organization. The mam- 

 mifera are more perfect than birds ; these than reptiles ; and 

 fishes are most inferior in this point of view. But in the in- 

 vertebrates the distinction is not the same. The principal 

 classes, the mollusca, articulata, and radiata, are superior 

 or inferior to each other, according to the point of view under 

 which we regard them, and the species which we compare. 

 We cannot place them, as with the vertebrates, the one after 

 the other, by declaring that the most imperfect animal of 

 the first is superior to the most perfect of the second. Each 

 of these types subdivides itself into groups of unequal per- 

 fection, which admit more easily of being arranged in a kind 

 of series than the classes themselves. 



If, in the comparison of difi^erent creations, we apply these 

 ideas, less simple perhaps, and more vague than the seale of 

 beings, but probably nearer the truth, we shall find, in the 

 first place, that the faunas of the most ancient formations 

 are mucli less imperfect than is often su})posed. The type 

 of the vertebrates is already represented there by fishes, and 

 the various classes of invertebrates are by no means reduced 

 to their inferior organisms ; among the mollusca, for exam» 

 pie, we find numerous gasteropods and cephalopods, which 

 are the most perfect orders of this class. It cannot, there- 

 fore, be affirmed, in regard to the invertebrates, that the 

 faunas of the most ancient formations are inferior in organi- 

 zation to those of the most recent formations. All that we 

 can prove is, that, among the vertebrates, the most perfect 

 animals at that time were fishes. If we are desirous to de- 

 duce from thence the true character of these faunas, we 

 will perceive that they may be compared to what our own 

 would be without reptiles, birds, and mammifera ; and that 

 all the types, from fishes inclusively, are there represented 

 by animals as perfect as those of the present time. 



The intermediate faunas, such as the Jurassic fauna, dif- 

 fer from the preceding and the most recent, by similar cha- 

 racters. The fishes, molluscs, articulata, and radiata of these 

 epochs, when compared with those of anterior and posterior 

 periods, present an organization of the same degree, and are 



