262 Professor Pictet on the Distribution of Fossils. 



truth of this law ; and who consequently may, perhaps, make 

 use of arguments in two senses. Certain very natural genera 

 may furnish the proof of what I state. If we compare, for 

 example, the skeletons of all the species of hares now living, 

 we shall have great difficulty, in regard to some of them, in 

 seizing the distinctive characters. If, then, we find a fossil 

 hare, and more especially if we find only fragments of one, 

 it may happen that it will appear referrible to one or to many 

 existing species. The palaeontologist who studies these re- 

 mains, may, as he chooses (so to speak), affirm that the species 

 is identical with existing species, or that it is an extinct 

 species, the distinctive characters of which probably resided 

 in the soft parts, and which the skeleton was not sufficient 

 to characterise. The rarity of these cases, and the little 

 importance, for the determination of formations, of the species 

 which give rise to doubts of this nature, prevent any actual 

 confusion resulting from this. 



Second Law. — The differences which exist between extinct 

 faunas and the animals now living, are so much greater in pro- 

 portion as these faunas are more ancient ; that is to say, the 

 more ancientl}^ formations have been deposited, the more 

 widely do the remains of the animals which they contain dif- 

 fer from those which now inhabit our globe. 



This law is shewn in a very evident manner, when we com- 

 pare the fossil remains of the animals of different geological 

 epochs. If we examine, for example, the shells of the ter- 

 tiary formations, we scarcely see any other forms but such as 

 are familiar to us ; while, if we study the faunas of ancient 

 formations, new and unknown forms will appear much more 

 frequently, and we shall be tempted, in many instances, to 

 call them eccentric or anomalous, since they deviate from 

 certain relations to which we are accustomed. 



If we wish to analyse more severely this first impression, 

 it might be said that the species of the most recent beds or 

 layers, belong, for the most part, to genera in which living 

 animals are classified ; while, if we descend further into the 

 crust of the earth, we are obliged to create more new ge- 

 nera to receive the forms of being ; and that there even ex- 

 ist, in the most ancient formations, conditions of organiza- 



