14 ESSAY ON CLASSIFICATION. 



reader beyond what is absolutely necessary to follow the 

 argument, nor dwell at any length upon the conclusions 

 to which they lead ; but will simply recall the leading 

 features of the evidence, assuming in the argument a full 

 acquaintance with the whole range of data upon which it 

 is founded, whether derived from the affinities or the 

 anatomical structure of animals, or from their habits and 

 their geographical distribution, from their embryology, or 

 from their succession in past geological ages, and the 

 peculiarities they have exhibited during each, 1 believing, 

 as I do, that isolated and disconnected facts are of little 

 consequence in the contemplation of the whole plan of 

 creation ; and that, without a consideration of all the facts 

 furnished by the study of the habits of animals, by their 

 anatomy, their embryology, and the history of the past 

 ages of our globe, we shall never arrive at the knowledge 

 of the natural system of animals. 



Let us now consider some of these topics more spe- 

 cially. 



1 Many points little investigated bridge in 1849; Boston, 1850, 1 vol. 



thus far by most naturalists, but to 8vo., p. 432.) Meanwhile, I refer in 



which I have of late years paid par- foot notes to such works as contain 



ticular attention, are here presented the materials already on hand for the 



only in an aphoristic form, as results discussion of these subjects, even 



established by extensive investiga- when presented in a different light. 



tions, though unpublished, most of I would only beg leave to add, that 



which will be fully illustrated in my in these references I have by no 



following volumes, or in a special means attempted to quote all the 



work upon the Plan of the Creation, writers upon the various topics under 



(See AGASSIZ (L.), On the Difference consideration, but only the most pro- 



between Progressive, Embryonic, and minent and most instructive, and 



Prophetic Types in the Succession of here and there some condensed ac- 



Organized Beings ; Proceed. 2nd counts of the facts in more elemen- 



Meeting Amer. Assoc. for the Ad- tary works, by the side of the origi- 



vancement of Science, held at Cam- nal papers. 



