2 DEFINITION OF AN INSECT. 



over there are many animals wliicli;, in the phrase of 

 naturalists^ are nearly allied to the creatures whose 

 history we propose to trace in the following pages ; that 

 is to say^ which agree with them in the principal out- 

 lines of their structure^ but which;, from characters of 

 more or less importance^ are separated from the true 

 Insects by the zoologist. These^ although often deno- 

 minated insects in common parlance, form no portion 

 of our present subject, so that, to avoid confusion, it 

 will be necessary to settle the boundaries of these 

 neighbouring groups, in order that the reader may 

 know exactly the nature of the entertainment to which 

 he is invited. 



Out bill of fare will consist exclusively of insects ; 

 but, what is an Insect ? An Insect may be defined as 

 an air-breathing articulated animal, with its body 

 divided into three distinct regions, Avith a pair of 

 jointed organs on its head, and Anth six legs. But 

 there are two objections to this definition in the 

 present case; in the first place, it does not apply 

 without exception to all the animals included in the 

 class of Insects; and in the second, if it did, it is 

 totally unintelligible to the beginner. The exceptions, 

 however, are so few in number, that they may be dis- 

 regarded for the present, and if the second objection 

 can be got rid of by a little explanation, the above 

 definition will serve to give us a sufficiently accurate 

 idea of what is and what is not an Insect. 



An articulated animal is one, the surface of whose 

 body exhibits a division into a number of rings, or 

 segments, and this character is very distinctly pos- 

 sessed by insects. Of these segments the number 

 \aries greatly in difierent groups of articulated ani- 

 mals, but in Insects it is pretty unilbrmly thirteen. 



