CHAPTER II 



LEADING GROUPS OF THE EXISTING SYSTEMS 

 OF ANIMALS 



SECTION I 

 GREAT TYPES OR BRANCHES OF THE ANIMAL KINGDOM 



The use of the terms types, classes, orders, families, genera, and 

 species in the systems of Zoology and Botany is so universal, that it 

 would be natural to suppose that their meaning and extent are well 

 determined and generally understood; but this is so far from being 

 the case that it may on the contrary be said that there is no subject 

 in Natural History respecting which there exists more uncertainty 

 or a greater want of precision. Indeed, I have failed to find anywhere 

 a definition of the character of most of the more comprehensive of 

 these divisions, while the current views respecting genera and species 

 are very conflicting. Under these circumstances it has appeared to me 

 particularly desirable to inquire into the foundation of these distinc- 

 tions, and to ascertain if possible how far they have a real existence. 

 And, while I hope the results of this inquiry may be welcome and 

 satisfactory, I am free to confess that it has cost me years of labor to 

 arrive at a clear conception of their true character. 



It is such a universal fact in every sphere of intellectual activity 

 that practice anticipates theory, that no philosopher should be sur- 

 prised to find that zoologists have adopted instinctively natural 

 groups in the animal and vegetable kingdoms, even before the ques- 

 tion of the character and of the very existence of such groups in 

 nature was raised. Did not nations speak, understand, and write 

 Greek, Latin, German, and Sanscrit, before it was even suspected 

 that these languages and so many others were kindred? Did not paint- 



