106 INTRODUCTION TO 



and the hinder section, to which the hind-legs and 

 hind-wings are attached, is the metathorax. In ap- 

 terous insects these divisions are the only ones dis- 

 tinctly determined, hut in those provided with wings 

 a more complex arrangement results from the mus- 

 cular apparatus requisite to produce their movements. 

 In its greatest state of development, (which it 

 attains among the coleoptera and orthoptera,) the 

 pro thorax (Manitrunk of Kirhy,) forms that large, 

 quadrate, rounded, or oblong piece intermediate be- 

 tween the head and abdomen, which, in popular and 

 descriptive language, is simply called the thorax. Its 

 surface is the pronotum of Burmeister, the thoracic 

 shield of Kirby. Its forms are too diversified to 

 be specified here; it commonly has an impressed 

 line down the centre, at other times the centre 

 rises into a longitudinal serrated ridge. The in- 

 ferior plate is named the prosternum by Burmeister: 

 (Antepectus, Kirby,) it is of more limited dimen- 

 sions than the surface plate, and usually projects 

 into a kind of angle beneath ; the anterior legs are 

 inserted, one on each side, towards the middle, and 

 the prothoracic spiracle is commonly a little behind 

 them. Viewed from above, the prothorax sometimes 

 forms merely a narrow ring like a collar, and in 

 certain tribes all traces of it disappear in the dorsal 

 aspect, the head being apparently articulated directly 

 with the mesothorax. The various changes of form 

 which the prothorax, as well as the other primary 

 divisions, undergoes in the different orders, together 

 with its appendages, and the degree of development 



