VARIATIONS OF METAMORPHOSIS. 55 



formations most conspicuously, should, from that very 

 circumstance, be considered the most typical group of 

 the whole. Now, we have already seen that the highest 

 developement of metamorphosis is chiefly, although, per- 

 haps, not exclusively, found among lepidopterous insects; 

 hence it follows, if our premises are correct, that this 

 order is unquestionably the type of the whole of the 

 Annulosa. This conclusion, however, does not appear 

 to have struck even the acute entomologist, who has laid 

 so much stress upon metamorphosis as to have declared 

 it the keystone of the natural system. Such, indeed, it 

 really is ; but, like every other character, it may, and 

 has been, repeatedly converted into the fabrication of 

 artificial systems. It has been well and justly remarked, 

 that " there is no principle of arrangement so good as 

 not to become worse than useless by being applied im- 

 properly." * The systems of Swammerdam, Lister, and 

 Ray in former periods, and of Latreille and others in our 

 own days, may be cited as proofs of this assertion. Mr. 

 MacLeay, perceiving this, has endeavoured to discover 

 the theory of variation in the metamorphosis of the An- 

 nulosa; and having, as he imagined, succeeded in his 

 research, he proceeded to make it the corner stone of his 

 system. It is singular, however, that he should have 

 overlooked one of the first objections which his ingenious 

 results lie open to ; for, after all his study, he confesses, 

 with the candour of a truly great mind, the impossibility 

 he finds in determining what insects constitute the per- 

 fection of the annulose circle. This difficulty, we think, 

 has originated from his adopting the two great divisions 

 of Clairville's Haustellata and Mandibulata as the basis 

 of his theory. 



(51.) On the variation of metamorphosis there is much 

 to be said, and more to be discovered. The subject, how- 

 ever, is so abstruse, and encumbered with so many dif- 

 ficulties, that we must touch upon it very briefly. It 

 has been well observed, that the variation of metamor- 

 phosis is only an index of the series of affinity, and not 



• Plor. Ent. p. 450. 

 E 4 



