INTRODUCTION. 5 



known cases agreeable perfumes like flowers, sandal-wood, 

 and mnsk. 



The legs are six in number, one pair to each division of 

 the thorax; they are always very slender and stick-like. 

 The front pair, however, as we pass from the lower to the 

 higher butterflies becomes more and more atrophied and 

 useless, first in the males, then in the females, until in the 

 highest family they are utterly useless, often not easy to 

 detect, and render this group practically four-legged in- 

 stead of six-legged. 



Their principal divisions are the femur (plural, femora) 

 or thigh, the tibia or shank— these two parts generally of 

 about equal length and indivisible; and the tarsus, the last 

 composed of five always unequal joints, armed beneath 

 with short spines and at tip with claws, a pad, and often 

 with paronychia or whitlows, a sort of membranous imita- 

 tive accompaniment of the claws, perhaps best seen in the 

 f ierids. 



The abdomen is formed of nine essentially simple seg- 

 ments. The males may be distinguished from the females 

 by the structure of the last segment, the females being pro- 

 vided with a pair of minute flaps, one on each side, which 

 protect and form part of the ovipositor, while the males 

 have side clasps and an upper median hook for clasping 

 the body of the female. The abdomen of the female when 

 filled with eggs is very much larger and fuller than that of 

 the male, and the sex can thus often be told at a glance. 



3. The Appearaxce of the Egg. 



The eggs of butterflies are very various in sculj^ture, and 

 though often very simple, are at other times exquisitely 

 ornamented. Tliey are usually broad and flat at the base, 

 and more or less rounded above. One class may be called, 

 in general, barrel-shaped; but this would include minor 



