106 
NATURAL HISTORY OF 
The next part of a coleopterous insect which re- 
quires some notice is the thorax , which it will suf- 
fice for our present purpose to describe as a single 
principal portion, intermediate between the head 
and abdomen. It is the seat of all the organs of 
motion, and is usually strong and muscular, as it 
forms the chief support of all the other parts of the 
body. It is generally wider than the head and nar- 
rower than the abdomen. The form of the upper 
and exposed portion is very variable : in an exten- 
sive tribe of beetles it is more or less heart-shaped, 
