204 LOUIS AGASSIZ. 



of the natural relations of the families among 

 themselves ; that one might therefore read the 

 genetic development of the whole class in the 

 history of creation, the representation of the 

 genera and species in the several families be- 

 ing therein determined ; in one word, that the 

 genetic succession of the fishes corresponds 

 perfectly with their zoological classification, 

 and with just that classification proposed by 

 me. The question therefore in characterizing 

 formations is no longer that of the numerical 

 preponderance of certain genera and species, 

 but of distinct structural relations, carried 

 through all these formations according to a 

 definite direction, following each, other in an 

 appointed order, and recognizable in the or- 

 ganisms as they are brought forth. ... If 

 my conclusions are not overturned or modi- 

 fied through some later discovery, they will 

 form a new basis for the study of fossils. 

 Should you communicate my discovery to oth- 

 ers I shall be especially pleased, because it 

 may be long before I can begin to publish it 

 myself, and many may be interested in it. 

 This seems to me the most important of my 

 results, though I have also, partly from per- 

 fect specimens, partly from fragments, identi- 

 fied some five hundred extinct species, and 



