INSECTS. 
13 
The Body in the major part of Insects is divid- 
ed into the thorax or upper part, and the abdo- 
men or lower part. In many of the Beetle tribe 
the back of the thorax is distinguished by a small 
triangular piece or division, situated at its lower 
part, between the juncture of the wing-sheaths : this 
triangidar part is termed Scutdlum or escutcheon. 
The under part of the thorax is called the breast, 
or Pectus, and in this the sternum is frequently 
distinguishable. The abdomen is marked into 
transverse sections, and the last joint terminates 
in the tail, or pointed extremity. The wing- 
sheaths or shelly coverings, in the Beetle tribe 
and some others, are termed Elytra or Coleoptra. 
The Limbs, in the major part of Insects, consist 
of three principal divisions j viz. the upper joint. 
Femur or thigh, the second joint. Tibia or leg, and 
the third. Tarsus or foot, which commonly consists 
of several small articulations, and is terminated 
by a dilated tip, with two hooked claws. 
In many Insects there are two small parts re- 
sembling minute bladders, fixed on a slender, 
short stem, and situated one under each wing: 
these parts are called Halteres, balancers, or 
poisers, and are only to be found in the two- 
winged insects : their supposed use is to keep the 
‘Insect steady during its flight, since if one of 
them be cut off, the animal flies with an unsteady 
motion. 
The majority of Insects are observed to be an- 
nual; finishing the whole term of their lives in 
the space of a year or less ; and many do not live 
