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PHILOSOPHY OF ZOOLOGY. 



PART III. 

 QN NOMENCLATURE, 



'JL HE ultimate object which the zoologist has in view, in 

 the employment of the preceding methods of investigation, 

 is to complete the History of Species. For the full accom- 

 plishment, however, of this end, it is not only necessary to 

 acquire a knowledge of their structure and functions, but 

 likewise of all their mutual relations. This last task can 

 only be executed, by calling to our aid the principles of ar- 

 rangement, and by distributing animals into divisions or 

 classes, according to the characters which they exhibit. At- 

 tempts of this kind have been made by numerous obser- 

 vers ; and the various systems which have been proposed, 

 differing from one another in the characters employed, and 

 the divisions recognised, intimate very plainly the difficul- 

 ties inseparable from the subject. 



The methodical investigation and distribution of Ani- 

 mals, would be comparatively easy, if the forms and modi- 

 fications of the different systems of organs exhibited con- 

 stant mutual relations. Thus, if we consider the organs of 

 any system to be in their most perfect state, when they ad- 

 mit into their structure the greatest variety of combinations, 

 and execute the greatest number of motions or functions, 



