GO INTRODUCTION. 



many pairs of limbs, distributed along its extent in 

 length. A similar correspondence is observable 

 through all the animal tribes. 



This relative proportion in the structure of ani- 

 mal forms in general, which results from the arrange- 

 ment of the motory organs, the distribution of the 

 nervous masses, and the energy of the circulating 

 system, should constitute the only basis upon which 

 the primary divisions of the animal kingdom may be 

 founded. 



We shall examine in the sequel successively, un- 

 der each of these primary divisions, what are the 

 characters next in importance to those just alluded 

 to, and which are therefore proper to follow in suc- 

 cession, as distinctive of the subdivisions of the ani- 

 mal kingdom. 



General distribution of the Animal Kingdom into four 

 grand divisions. 



If we divest ourselves of prejudices founded on 

 the divisions of the animal kingdom formerly recog- 

 nised, and consider animals without reference to 

 their relative size or utility, our own degree of know- 

 ledge respecting them, or any other extraneous 

 circumstances, we shall find that there are four 

 principal forms after which all living beings appear 

 to have been modelled. The basis of these distinc- 

 tions is laid on the nature and organization of the 

 several creatures themselves : the ulterior divisions 



