THE CLASSIFICATION OF INSECTS 91 



The swallow-tails {Papilionid(c) are a very large family 

 of handsome insects which abound in tropical countries. 

 The six legs are fully developed in both sexes, while the 

 wing neuration differs from that of all other butterflies. 

 The larva is cylindrical, never hairy, but often with a curious 

 retractile scent organ behind the head. The pupa, which 

 has two projecting tubercles or " nose-horns," is fixed to 

 a silken pad by its cremaster and kept upright by a silken 

 girdle fastened to a stem of the food-plant. The British 

 swallow-tail butterfly (Papilio machaon) is still common 

 in some of the fen districts of the eastern counties. The 

 scarce swallow-tail {Papilio podalirius) and the Apollo 

 (Parnassius apollo) have both been captured in this 

 country, but are not indigenous. This family includes 

 the enormous bird-winged butterflies (Ornithoptera) of 

 the Indo-Malayan region. 



The Pieridce, or "whites," are allied to the swallow- 

 tails, but have a characteristic wing neuration. Moreover, 

 the larva? are more or less hairy, while the pupa has only 

 one " nose-horn." The large cabbage butterfly (Pieris 

 brassicce), the brimstone (Gonopteryx rhamni), and the 

 clouded yellow (Colias edusa) are well-known examples of 

 this family, which is represented in all parts of the world. 



The Nymplialidie are the largest and most dominant 

 of the butterfly families. In both sexes the fore-legs are 

 useless for walking. The larvae vary greatly in form, 

 being spiny or hairy in many genera, though smooth in 

 others. The pupre, which often display metallic areas, and 

 thus merit the name " chrysalis," have two " nose-horns " ; 

 but they hang head downward from a silken pad, and 

 are never girdled. The NympJialidce are usually divided 

 into eight sub-families, only two of which are repre- 

 sented in Britain. The Satyr hue comprise the meadow- 

 browns and their kindred, while the Nymphalincc 



