INSECTA. 559 



ever, a considerable difference of opinion prevails, as to the 

 characters which should be employed in the formation of 

 the orders and other subordinate divisions. 



Since the days of SWAMMERDAM, there have not been 

 wanting naturalists who have regarded the metamorphoses 

 of insects, as furnishing the most suitable characters for 

 primary divisions. But, instead of adopting the four forms 

 of metamorphoses of that author, they have divided insects 

 into such as do not undergo changes of form in the third 

 or pupa state, and such as do undergo changes. Thus 

 WILLOUGHBY (in Rail Historia Insectorum, p. 3.) divides 

 insects into otptTotfAo^ara and ^r^o^ttsv*, terms for which 

 Dr LEACH has substituted Ametabolia and Metabolia. 

 Strong objections may be urged against the classification of 

 insects from such characters. All insects, even the et^rxuc^- 

 q>ur<*> undergo changes, as they cast their skins repeatedly, 

 and reach maturity by degrees. The extent of difference 

 between the forms of the larva and imago state is not the 

 same in the genera of the same family or order. The dif- 

 ferences which insects exhibit in their changes arc merely 

 in degree, not in kind. But the strongest objection to 

 which this method of classification is liable, arises from the 

 circumstance of employing the characters furnished by the 

 immature state of insects, in order to classify insects in 

 their mature state when these characters do not appear. 



LINSLEUS, to whom zoology in all its branches was great- 

 ly indebted, gave to insects a uniformity of nomenclature, 

 and a methodical arrangement, greatly superior to all his 

 predecessors. His primary divisions were taken from cir- 

 cumstances connected with the condition of the wines, 



o 



The simplicity of this method, and the obviousness of the 

 characters which have been employed, have secured for 

 this system a decided preference among the entomologists of 

 Britain. Perhaps the strongest objection which can be 



