HYMENOPTERA : CLASSIFICATION. 385 



the order of insects in question, this mode of viewing 

 their classification has hitherto been too much neglected to 

 enable us to follow it out in a work like the present, which 

 ought to convey facts rather than theories ; I have, never- 

 theless, thought it proper to notice the subject, which is in 

 fact one which materially influences every zoological group. 

 In the meantime, it may be more conducive to our present 

 purpose to notice the variation of several of the more im- 

 portant organs, and the causes upon which such variations are 

 dependent. Although the nature of the nourishment of all 

 hymenopterous insects be alike, it does not follow that the 

 mouth of all should be of an uniform structm*e; neither, 

 although consisting of the same parts and number of pieces, 

 is it requisite that they should be formed upon the same 

 model. The construction of the nest and the preparation 

 and transporting of the materials employed therein, as well 

 as the form of the flowers from which the different species 

 collect their hone}', are considerations which modify, in a 

 greater or less degree, the structure of the organs of the 

 mouth ; thus, in those species which collect honey from 

 flowers for their oaati support alone, as the TenthredinidcBy 

 IchneumonidcB, &c., the lower lip or tongue, and the lower 

 jaws, are short and narrow ; but when the insect has to col- 

 lect a supply of food, not only for its own support, but also 

 for that of its progeny, these parts are much more developed, 

 as is also the case when the honey is placed at the bottom of 

 tubular flowers, such as the LabiatcB, &c., which are much 

 frequented by some of the long-tongued bees : the same 

 parts are short and broad in the ants, wasps, &c., because 

 they frequent flowers composing the heads of the Umhelli- 

 fer(B, from the almost flat siu-face of which they collect the 

 honey, as well as the sap flowing from the wounds of trees, 

 &c., without trouble ; moreover, this organ is thus modified to 

 serve as a trowel for the smoothening of the inner surface of 



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