206 ESSAY ON CLASSIFICATION. Part I. 



by Cuvier, with the addition of Gordius; while his class Sterelmintha has the 

 same circumscription as the order Intestinaux PARENcm'iiATEUx of Cuvier. Generally 

 speaking, it should not be understood that the secondary divisions mentioned by the 

 diflerent authors, whose systems I have analyzed here, were established by them. 

 They are frequently borrowed from the results obtained by special investigators of 

 isolated classes. But it would lead me too far, to enter here into a discussion 

 of all these details. 



This growing resemblance of the modern systems of Zoology is a very favorable 

 sign of our times. It would, indeed, be a great mistake to assume, that it is solely 

 owing to the influence of different authors upon one another ; it is, on the con- 

 trary, to a very great extent, the result of our better acquaintance with Nature. 

 When investigators, at all conversant vnth the present state of our science, must 

 possess nearly the same amount of knowledge, it is self-evident that their views 

 can no longer differ so widely as they did when each was familiar only with 

 a part of the subject. A deeper insight into the animal kingdom must, in the 

 end, lead to the conviction that it is not the task of zoologists to introduce order 

 among animals, but that their highest aim should be simply to read the natural 

 affinities which exist among them, so that the more nearly our knowledge embraces 

 the whole field of investigation, the more closely will our opinions coincide. 



As to the value of the classes adopted by Owen, I may further remark that 

 recent investigations, of which he might have availed himself, have shown that the 

 Cirripedia and his Epizoa are genuine Crustacea, and that the Entozoa can no 

 longer be so widely separated from the Annellata as in his system. With reference 

 to the other classes, I refer the reader to my criticism of older systems, and to 

 the first section of this Chapter. 



It is a great satisfaction for me to find that the views I have advocated in 

 the preceding sections, respecting the natural relations of the leading groups of 

 the animal kingdom, coincide so closely with the classification of that distinguished 

 zoologist, Milne-Edwards, lately presented by him as the expression of his present 

 views of the natural affinities of animals. He is the only original investigator 

 who has recently given his unqualified approbation to the primai'y divisions first 

 proposed by Cuvier, admitting, of course, the rectifications among the group of 

 secondary rank, rendered necessary by the progress of science, to which he has 

 himself so largely contributed. 



As to the classes adopted by Milne-Edwards, I have little to add to what I 

 have already stated before, with reference to other classifications. Though no 

 longer overruling the idea of plan, that of complication of structure has still too 

 much influence with Milne-Edwards, inasmuch as it leads him to consider as classes, 

 groujis of animals which differ only in degree, and are therefore only orders. 



