INTRODUCTION. 
80 
Each of these three sections is then divided info 
tribes, according to characters derived from the ca- 
terpillars and the perfect insect. . Among those 
furnished by the latter, the most important are con- 
sidered to be the number of ambulatory legs and 
the form of the palpi. The genera are characterised 
by the form of the caterpillar and chrysalis, by the 
dispositions of the nervures of the wings, the form 
of the antennae, legs, palpi, thorax, &c. of the per- 
fect insect. 
