CHAPTER III 



NOTICE OF THE PRINCIPAL SYSTEMS OF ZOOLOGY 



SECTION I 

 GENERAL REMARKS UPON MODERN SYSTEMS 



Without attempting to give an historical account of the leading 

 features of all zoological systems, it is proper that I should here com- 

 pare critically the practice of modern naturalists with the principles 

 discussed above. With this view it would hardly be necessary to go 

 back beyond the publication of the Animal Kingdom, by Cuvier, 

 were it not that Cuvier is still represented by many naturalists, and 

 especially by Ehrenberg,^ and some other German zoologists, as favor- 

 ing the division of the whole animal kingdom into two great groups, 

 one containing the Vertebrates, and the other all the remaining classes, 

 under the name of Invertebrates, while in reality it -ivas he who first, 

 dismissino; his own earlier views, introduced into the classification 

 of the animal kingdom that fourfold division which has been the 

 basis of all improvements in modern Zoology. He first showed that 

 animals differ, not only by modifications of one and the same organic 

 structure, but are constructed upon four different plans of structure, 

 forming natural, distinct groups, which he called Radiata, Articulata, 

 Mollusca, and Vertebrata. 



It is true that the further subdivisions of these leading groups have 

 undergone many changes since the publication of the Regne animal. 

 Many smaller groups, even entire classes, have been removed from one 

 of his "embranchments" to another; but it is equally true that the 

 characteristic idea which lies at the bottom of these great divisions was 

 first recognized by him, the greatest zoologist of all time. 



^ Die Corallenthiere des rothen Meeres (Berlin, 1834). 



