Insects. 1 793 



logical inferences from positive observations. We want the know- 

 ledge of those kindred forms that may intimately connect the Stylo- 

 pites with forms already known : and in the absence of that know- 

 ledge we want logical reasoning on the facts already within our reach. 



In the second place, I assume, that certain positions are established 

 by the very general consent of naturalists: e.g., that organised beings 

 divide into animal and vegetable : that animals are constructed on 

 certain different plans, as vertebrate, articulate, radiate : that certain 

 articulate animals are apterous, as Crustacea, Arachnida, Myriapoda ; 

 and certain others winged, as Lepidoptera, Diptera, Hymenoptera ; 

 that winged articulates constitute a group of themselves ; that Stylops 

 is an organized being; an animal ; an articulate ; a winged articulate : 

 that at this point our knowledge of its affinities ceases, and therefore 

 that at this point the present enquiry begins. 



In the third place, I assume, that the just arrangement of winged 

 articulates or insects depends on the combination of three series 

 of functions, viz., metamorphosis, nutrition, and locomotion : these 

 have given rise to three artificial methods of arrangement called the 

 metamorphotic, maxillary, and alary, respectively promulged by 

 Swammerdam, Fabricius, and Linneus : but I assume that no method 

 can be natural that is not in accordance with all three series of func- 

 tions, and indeed, with all series of functions that may by their varia- 

 tion furnish us with characters whereby to separate given divisions 

 into minor divisions. 



Division of the Subject. 



In accordance with the foregoing assumptions, it becomes necessary 

 to divide the subject into its constituent parts and to consider them 

 seriatim. The three series of functions employed by entomologists 

 in these varied methods of arrangement must be consulted, both with 

 reference to Stylops itself and to winged insects generally ; and here 

 it must be observed, that in thus selecting three series of functions to 

 the exclusion of others, I do so solely from necessity (all our know- 

 ledge having relation thereto), and not because I would assert the su- 

 periority of these functions over others, of which hitherto we have taken 

 no account. Each of these series of functions having then to be con- 

 sidered twice, i. e. 9 positively and comparatively, we arrive at a divi- 

 sion of the subject into six sections. — 1. Economy and Metamorphosis 

 of Stylops. 2. Comparative Economy and Metamorphosis of Stylops. 

 3. Anatomy of the Mouth of Stylops. 4. Comparative Anatomy of 



