10G 
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 
prothorax (Manitrunk of Kirhv,) 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. View r cd 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 meso thorax. 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 
