Ixxiv PRELIMINARY SKETCH OF THE 



tural classes of vertebrated animals, he disco- 

 vered in the respective quantity of respiration, 

 the reason of the quantity or degree of motion, 

 and, consequently, the peculiar nature of that 

 motion. This last, gives rise to the pecu- 

 liar form of their skeletons and muscles ; and 

 with it, the energy of their sensations, and the 

 force of their digestion, are in a necessary re- 

 lation. Thus zoological arrangement, which 

 had hitherto rested on observation alone, 

 assumed, in the hands of our illustrious au- 

 thor, for the first time a truly scientific form. 

 Calling in the aid of comparative anatomy, it 

 involves propositions applicable to new cases ; 

 it becomes a means of discovery, as well 

 as a register of facts, and by correct rea- 

 soning, founded on copious induction, it par- 

 takes of the demonstration of mathematics, 

 and the certainty of experimental knowledge ; 

 in short, it becomes what it never was before, 

 a science. 



Our author having examined the modifica- 

 tions which take place in the organs of cir- 

 culation, respiration, and sensation, in the in- 

 vertebrated tribes, and having calculated their 

 necessary result, has formed a new division, 

 in which these animals are arranged accord- 

 ing to their actual relations. The mollusca. 



