366 



ORDERS OF PTILOTA. 



pressed, vnth. the segments distinct, and terminated in the 

 males of many species by hooks which are employed during 

 coupling. In some species both sexes are provided with 

 two or three very long and slender hairs or bristles, as in 

 the EphemercB, whilst the female Raphidia has a single long 

 and sword-like appendage. In none of the species, however, 

 do we find any instrument acting as the sting of the Hyme- 

 nop t era. 



There is considerable diversity in the transformation of 

 this order ; the larvae are hexapod, and very variable in their 

 habits and habitations. Many of them reside in the water, 

 where they are either predaceous or vegetable feeders, some 

 few feeding upon decayed plants, others in holes which they 

 form in the sand. The majority are carnivorous, and feed 

 upon other insects ; the aquatic species are provided with 

 an apparatus for obtaining a supply of fresh air, which has 



some resemblance to 

 lateral series of ex- 

 ternal gills, but which 

 are, in reality, the 

 tracheae greatly di- 

 lated externally. The 

 pupse are as active 

 as the larvae in the 

 dragon-flies and some 

 other species ; but in 

 both these states of 

 these insects the 

 mouth undergoes a 

 remarkable modifi- 

 ti^e cation of form. In the 

 EphemeridcB there is 

 another curious modification in the transformations, the in- 

 sects, after arriving at the winged state, throwing off a thm 



A, the Dragon-fly making its escape from the pupa — 

 same, drying its wings. 



