364 NATURAL ARRANGEMENT OF INSECTS. 



or interruption,, therefore, of the circular succession of 

 the Aptera, as here arranged, appears to be at this point ; 

 since the resemblance which certain extreme Crustacea 

 possess to such forms as Oniscus, renders the union of 

 both sufficiently clear. From the Diptera, therefore, 

 to the Arachnida, the passage is at once opened by Nyc- 

 teribia ; from the spiders to the centipedes, and from 

 these to the Crustacea, the line of affinity is preserved; 

 while what has been said of the resemblance between 

 the marine and the land fleas, is all but demonstra- 

 tive that the whole form a circle, since the situations 

 of Diptera and Suctoria are established, not by their 

 own union, but by their connection to the orders which 

 either precede or follow them. 



(323.) We now come to the analogies, which may be 

 thus exhibited as referring to the Ptilota. 



Analogies of the APTERA to the PTILOTA. 



Orders of the ,*../;,. Orders of the 



Aptera. Analogies. Ptilota. 



C Sub-typical : feet the same in their 7 

 ARACHNIDA. \ larva and perfect state. j 



rPre-e 

 < circl 

 C. larv 



r Pre-eminently typical of their own T. 



MYRIAPODA. -J circles ; feet variable in their > LEPIDOPTERA. 



" irva and perfect state. J 



CRUSTACEA. Head large. Aquatic. NEUROPTERA. 



SUCTORIA. Body encased in hard plates. COLEOPTERA. 



DIPTERA. Winged in their adult state. HYMENOPTERA. 



(324.) In our former volumes, we have had frequent 

 occasion to notice the occasional transportation, as it 

 were, of the analogies of the typical groups in two dif- 

 ferent circles ; as a consequence of some variation in the 

 dispositions of the groups, thus brought into parallel 

 comparison, for which we were unable to account. We 

 have before observed that the tendency of metamor- 

 phosis in the Ptilota is to give wings to the perfect in- 

 sect ; while, in that of our Aptera, it is to give an 

 increase in the number of feet. Now, if this theo- 

 retically be true, the philosophical inference will be, 

 that the Myriapoda are the types of the Ptilota ; 



