10 NATURAL ARRANGEMENT OP INSECTS. 



attempts to establish any sort of relationship between 

 them and the Vertebrata. This has originated from 

 two causes : firstly, from considering the Annulosa as 

 an isolated group, whose divisions were not subject to 

 any general or comprehensive principles ; and secondly, 

 from adopting as the basis of their arrangement a prin- 

 ciple of classification which, as will be shown in the 

 sequel, appears absolutely artificial. Vague,, therefore, N 

 as one or two of the above analogies may appear, it is 

 yet some satisfaction to see how strong and singularly 

 beautiful they are in others. Of all insects, for instance, 

 none are so perfectly organised for walking as the Ap- 

 tera,) since here we find the centipede, the lulus, and 

 many other creatures, whose legs may be almost termed 

 innumerable. The quadrupeds, which they thus re- 

 present, are precisely in the same position, since they 

 are the most perfect walkers of all the Vertebrata. The 

 four-winged insects forming the class Ptilota, and at 

 the head of which stand the butterflies, may truly be 

 called the birds of annulose animals, which they further 

 represent by the feathery down with which their wings 

 are covered and the brilliant colours with which both 

 are ornamented. The resemblance between the serpents 

 and the Annelides will be admitted by every one not 

 blinded by system ; for who that looks upon an earth- 

 worm will not be reminded of a snake ? The least or- 

 ganised of ah 1 the Annulosa are the intestinal worms, some 

 of which are so low in the scale that no articulations 

 of their body can be discerned. In this imperfection 

 they resemble the amphibians, the most imperfect of 

 the Vertebrata, and where the naked skin is entirely 

 unprotected. Lastly, the Cirrhipedes, without hav- 

 ing the least resemblance in external form to fishes, 

 nevertheless resemble them in having the body covered 

 with hard plates, and always living in the water. 

 These are only the most prominent analogies, but they 

 are such as will strike a common observer ; and however 

 they may be extended hereafter, are at least sufficient to 



