4 DEFINITION OF THE TERM INSECT. 



has expressly excluded all apods \ From other passages 

 in his works, it appears that he regarded the Vermes, &c. 

 either as larva;, or as produced spontaneously and not 

 ex ovo b . 



This definition of an insect, though partly founded on 

 misconception, as well as his primary division of animals 

 in general, is by no means contemptible. If you look at 

 a bee or a fly, you will observe at first sight that its body 

 is inserted, being divided as it were into three principal 

 pieces — head, trunk, and abdomen ; and if you examine 

 it more narrowly, you will find that the two last of these 

 parts, especially the abdomen, are further subdivided. 

 And this character of insertion, or division into segments, 

 more or less present in almost every insect d , is not to be 

 found (with the exception of the Crustacea, which Ari- 



a 'Ru'TSftot iro\vzohei y.iu yotq srt vocvrx. De Part. Animal. 1. iv. C. 6. 



h Hist. Animal. 1. iv. c. 19. 



c The insection that distinguishes these parts, the abdomen espe- 

 cially, is most visible in the majority of the Hyvienoptcra and Diptera 

 orders ; next in some Coleoptera, as the Lamellicorn tribes, &e. and 

 the Lepidoptera. Latreille is of opinion, that the two last segments 

 of the thorax in some insects are represented by the first of the 

 abdomen, and that the upper half segment of this part in Coleoptera 

 also represents the same. Latr. De quelques Appendices, &c. An- 

 nates Generates des Sciences Physiques. A Bruxelles, vi. livrais. xviii. 

 14. In fact, in the Lepidoptera, when the abdomen is separated from 

 the trunk, this segment usually remains attached to the latter. In 

 the Myriapods, the trunk is to be distinguished from the abdomen 

 only by its bearing the three first pair of legs. 



d There is no general rule without exceptions, and no character is 

 so universal as to be distinctly exhibited by every member of a class 

 or other natural group. Thus, in the majority of the mites (Acarus 

 L.) the body is marked by no segments, and the only articulation or 

 incision is in the legs, palpi, &c. But as the exception does not make 

 void the rule, so neither does the extenuation or absence of some 

 primary character at its points of junction with others, in some indi- 

 viduals, annihilate the class or group. 



