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dichotomies : the dichotomy to which I have here to allude is the 

 division of insects into Mandibulata and Haustellata. Nov? every 

 division founded on the presence or absence of a particular cha- 

 racter should be received vrith the greatest caution, because the 

 second group in which the character is absent* is sure to be too 

 comprehensive. Mr. MacLeay,-|- himself no great friend to dicho- 

 tomies in general, is completely led away by this particular one. 

 He considers the classes I. II. and VI. of the foregoing table to 

 constitute one grand order, and the classes III. IV. V. and VII. 

 to constitute another ; and, after Clairville, he calls the former 

 order, Haustellata, and the latter, Mandibulata. Mr. Mac Leay's 

 name is a tower of strength to any theory ; and his authority, 

 added to the plausibility of the idea, has really given such a 

 truth-like appearance to this division, that we see it now univer- 

 sally adopted. Let us examine its worth. First, I would ask, 

 Can distinctive characters, thus drawn from part only of the 

 external anatomy of insects, be sound, when to enforce them we 

 are compelled to neglect various other characters which we have 

 been accustomed to consider all important? Scopoli has said, 

 " Classes et genera naturalia non sola instrumenta eiharia, non 

 solce antennce nee solce alee constituunt ;" but our dichotomizing 

 entomologists tell us, that neither antennae, nor wings, nor habit, 

 nor metamorphosis, are to be regarded at all, but " sola instru- 

 menta cibaria ;" at least, they infer this by separating Orthoptera 

 and Hemiptera, by the intervention of several orders totally un- 

 related to either of them, a disruption which no nature-loving 

 naturalist could for a moment admit. The truth is, there are 

 seven kinds of mouth in insects, so distinct that good classes 

 could be built on them,J — classes which would confirm those 



* And, be it observed, Haustellata merely means not mandihulate ; it does 

 not propose to assert that the contents of the tribe so named need have a 

 particular kind of haustellata mouth, or any mouth at all. 



•|- Mr. MacLeay has written a little pamphlet on the impropriety of the 

 dichotomous system, which I recollect reading, when published, with consi- 

 derable pleasure. I forget its title. 



J If the reader happen to be unacquainted with the terms which I have 

 used in characterizing the mouth, he will find them accurately and elaborately 

 described in hid. to Ent. Vol. III. p. 393, et seq. The orders of Fabricius de- 

 pend entirely on the formation of the mouth. See Systema Entomologiee. 



c 



