Elizabeth Cary Agassiz, Louis Agassiz: his life and correspondence, third edition

[204] 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 being 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 organisms as they are brought forth. . . . If my conclusions are not overturned or modified through some later discovery, they will form a new basis for the study of fossils. Should you communicate my discovery to others 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 perfect specimens, partly from fragments, identified some five hundred extinct species, and