368 ORDERS OF PTILOTA. 



the Atropos pulsatorius, belonging to the last-named family, 

 and which is ordinarily found amongst books 

 and papers. 



From the considerable variation, both in 

 structure and transformations of these insects, 

 there has been a considerable diversity of 

 opinion relative to the extent of the order, the 

 Libellidce and Ephemerce, having an aquatic 

 pupa, being regarded by some authors as the 

 types of distinct orders. The same has also been maintained 

 respecting the Termitidcs, or white ants, and the caddice flies 

 {Phryganece), which last have been formed by Mr. Kirby into 

 the order Trichoptera, whilst, by Latreille, the order is main- 

 tained in its Linnsean extent. I have adopted the views of 

 modern English authors, separating only the PhryganecB. 

 The order is therefore divisible into sections, which exhibit the 

 following succession of natural relations, founded upon the 

 habits and transformations of the groups: — 1. Carnivorous 

 insects, having aquatic larvae and active pupae, bearing a 

 certain resemblance to the imago ; 2. Carnivorous insects, 

 having terrestrial or aquatic larvae and incomplete pupae; 

 3. Carnivorous or omnivorous insects, terrestrial in all their 

 states, and having active pupae differing from the imago only 

 in wanting wings. Latreille, by introducing the PhryganecB 

 into the order (and which correspond with the Ephemerce in 

 the aquatic habits of the larvae and the rudimental structure 

 of the mouth of the imago, and forming together Dumeril's 

 family Agnatha or Buccelles), adds a fourth group of herbi- 

 vorous insects, with aquatic case- or caddice-forming larvae, 

 and inactive, incomplete pupae ; terminating the order with 

 those species of PhryganecB which have the wings very 

 slightly reticulated, resembling, in many respects, some of 

 the least perfectl}^ organized Lepidoptera. This last re- 

 lationship is admitted by most recent authors, so that the 

 neuropterous insects may be arranged with the Trichoptera 



