INTRODUCTION 
I.— THE CLASS INSECTA. 
As the Lepidoptera (Butterflies and Moths) are an Order of the Class 
Insecta or true Insects, a few words are requisite to indicate the 
structure of these animals. 
The entire class is associated with three others, viz., the Arachnida 
(Spiders, Scorpions, &c.), the Myriopoda (Centipedes, Millipedes, &c.), 
and the Crustacea (Crabs, Lobsters, &c.), to form the great sub- 
kingdom ARTHROPODA. This immense assemblage is characterised 
by the body consisting of a series of rings or segments (somites) bearing 
hollow jointed limbs ; and by the integument being so hardened and 
solidified by the peculiar deposit chitine^ as to constitute a more or less 
rigid external skeleton to which the muscles are attached. The rings 
or segments of the body succeeding those which unite to form the head 
do not, as in the higher members of the sub-kingdom Vermes, present 
a repetition of the same structure throughout their series, but tend 
with more or less distinctness to form two separate groups or regions 
to which special organs and functions are allotted. These two unequal 
sets or groups of segments are respectively termed thorax (the anterior) 
and abdomen (the posterior) ; and, speaking generally, the organs and 
functions of locomotion may be said to reside in the former, and those 
of nutrition and reproduction in the latter. 
The Crustacea are separated from the rest of the Arthropoda by a 
respiratory system working by gills (hranchice)^ adapted to their aquatic 
life ; while all Insects, Myriopods, and Arachnids are alike in direct 
aerial respiration by breathing-tubes (trachece) traversing the body 
and opening on its exterior by stigmata ^ — or (in the case of certain 
Arachnids only) by pulmonary sacs. Associated with this important 
distinction there are others of much note in external structure. Thus, 
the Crustacea have two pairs of antenna3^ — other Arthropods but one 
pair ; in the former there is a second pair of inferior jaws (maxilloe) 
functionally active, — but these in the other classes are united to form 
the under- lip (lahitim) ; the abdominal limbs of Crustaceans have no 
representatives in adult Insects or Spiders (though homologous append- 
VOL. I. A 
