FORMER DIVISION OF THE APTERA UNNATURAL. 36l 



the annulose body (and this often very obscurely ), to 

 indicate their connection to the annulose circle. The 

 very principle, therefore,, of introducing the mode of 

 respiration as a ground for founding classes and orders, 

 is radically vicious and unphilosophical. 



(319-) The effect of attaching this imaginary im- 

 portance to the respiratory organs of insects, has led to 

 all that confusion and opposition of opinion, which might 

 naturally have been expected. The integrity of the 

 Aptera being once destroyed by the separation of the 

 Crustacea, and the principle being unthinkingly ad- 

 mitted, innumerable other dislocations followed. New 

 classes and new orders were proposed, and attempted to 

 be defined, by all who built their systems upon respir- 

 ation; and this was pushed so far, that the entire dis- 

 tribution of the Annulosa has actually been made to 

 hinge upon this single circumstance.* In proportion 

 to the multiplication of these new " classes," so was the 

 disunion of sentiment among those who advocated the 

 respiratory system ; they neither agreed, in fact, with 

 each other, nor with themselves. Dr. Leach changed his 

 System of the apterous groups two or three times ; La- 

 treille has done the same ; and ultimately we find 

 Messrs. Kirby and Spence rejecting all these, and pro- 

 posing a division called Aptera, which they themselves 

 are dissatisfied with, as not a natural, but a provisional 

 order. No wonder, therefore, that all these conflicting 

 theories "have much perplexed systematists," who really 

 seem to have become bewildered by their own refine- 

 ments. 



(320.) Now, it would be well to ask, whether the 

 respiratory theory of entomologists is supported by any 

 analogous instances in other classes of animals ? and 

 whether the possession of gills, or sacs, or tracheae, have 

 been looked upon, by zoologists in general, of sufficient 

 importance to create distinct classes or orders ? No 



* See Dr. Leach's arrangement, as given in Samouelle, Entom. Com- 

 pend. 75. 



