6 NATURAL ARRANGEMENT OF INSECTS. 



of annulose animals,, while in many other respects they 

 show such a strong affinity to the radiated class (Ra- 

 diata). To understand the perfection of structure in 

 any given group, we must always draw our definition 

 of that group from its pre-eminent types ; but,, if we 

 wish to know how it blends into other groups, the ab- 

 errant examples, or such as are furthest removed from 

 the typical structure, must be alone regarded. No ani- 

 mals can be more unlike each other than a monkey and 

 a butterfly, each of which are the types of their own 

 class ; but when we look to an eel (Myxme) without 

 eyes or fins, or even a firm skeleton, we can have no 

 great difficulty in comparing it with the leech or the 

 earth-worm: the Myxine, in fact, is the last of the ver- 

 tebrate circle, while the Annelides are the first which 

 present themselves, on quitting the Vertebrata, and en- 

 tering the Annulosa. 



(7.) Our next question, regarding the PRIMARY 

 DIVISIONS of the annulose animals, is not so easily dis- 

 posed. Were we to lay before the reader all the con- 

 flicting opinions that have been promulgated on this 

 subject, we fear, even did our space admit of such de- 

 tails, we should probably perplex and certainly weary 

 him. It has been customary, indeed, for authors to 

 state the reasons which may lead them to reject the 

 theories of others ; and this, to a certain extent, is both 

 necessary and useful. But in the present case, it would 

 lead to so much discussion, that it must from necessity 

 be avoided. Our object is, not to criticise the opinions 

 of others, but make good, so far as we can, our own 

 theory upon the natural arrangement of all animals. 

 The plan, therefore, which we have hitherto pursued in 

 other classes will be continued to this : and the results 

 must be our apology for rejecting all former arrange- 

 ments of the Annulosa. We shall therefore first in- 

 timate what appear to be the five great divisions or 

 classes of the insect world, and then point out their 

 analogies to all other animals. The Annelides, as already 



