SKETCHES OF BRITISH INSECTS. 



CHAPTER I. 

 INTRODUCTION. 



LL Animals may be included in one or other of the 

 following great Divisions or Sub-Kingdoms, as they 

 are termed: — I. Vertebrata, IL Mollusca, 

 III. Artiiropoda, IV. Vermes, V. Echinodermata, 

 VI. Cgelenterata, VII. Protozoa. Insects, the sub- 

 ject of the present volume, belong to the Sub-Kingdom 

 Arthropoda, i.e., ''having feet at the joints," from 

 dpOpov "a joint," and ttovq, TrodSg, "a foot;" the term 

 implying that the animals are possessed of jointed ap- 

 pendages articulated to the body. Not only insects, 

 therefore, but the Myriapoda (centipedes), Arachnida 

 (spiders, mites, scorpions), and Crustacea (lobsters, 

 crabs, etc.,) belong to the Arthropoda, for in all these 

 four classes we find jointed appendages articulated to 

 the body. The Aithropoda are again divisible into 

 two large natural groups according to their mode of 

 respiration. In the Crustacea the respiration is aquatic, 

 in the three other classes it is aerial ; in the former it 

 is carried on by means of special organs called hranchioey 

 or where no such organs exist by means of the whole 



B 



