342 NEUROPTERA CHAP. 



and, as a matter of convenience, arrange them in five 

 divisions : 



1. Mallophaga. Permanently wingless Insects, living on the bodies of birds 



or mammals. (Development very imperfectly known.) Fam. 1. 

 Mallophaga. 



2. Pseudoneuro2)tera. Insects with wings in adult life (in some cases wings 



are never acquired). The wings are developed in a visible manner 

 outside the body. There is no definite pupa. Live entirely on land. 

 Fam. 2. Embiidae ; 3. Termitidae ; 4. Psocidae. 



3. Neuroptem amphibiotica. Wings developed as in division 2. Three ocelli 



usually exist. Life aquatic in the early stages. Fam. 5. Perlidae ; 

 6. Odonata ; 7. Ephemeridae. 



4. Neuroptera planipennia. Wings developed internally ; not visible in early 



stages, but becoming suddenly evident when the pupal form is 

 assumed. Mandibles present in the adult Insect. Life in early 

 stages aquatic or terrestrial. Fam. 8. Sialidae; 9. Panorpidae ; 10. 

 Hemerobiidae. 



5. Trichoptera. Development as in division 4. Mandibles absent in the adult 



Insect. Life aquatic in the early stages. Fam. 1 1 . Phryganeidae. 



The families we have enumerated in the preceding scheme are 

 now generally adopted by entomologists. Great difference of 

 opinion exists, however, as to the groups of greater value than 

 the family, and for a long time past various schemes have been 

 in vogue. Though it is necessary to allude to the more important 

 of these systems, we can do so only in the briefest manner. 



Some of the families of Neuroptera are similar in many points 

 of structure and development to Insects of other Orders ; thus 

 Termitidae are somewhat allied to Blattidae, Perlidae to Phas- 

 midae in Orthoptera, while the Phryganeidae or Trichoptera make a 

 considerable approach to Lepidoptera. Some naturalists among 

 whom we may mention Burmeister and Grassi unite our Aptera, 

 Orthoptera, and most of our Neuroptera into a single Order 

 called Orthoptera. Others treat our Neuroptera as consisting 

 of eight or nine distinct Orders ; these, together with the names 

 proposed for them, we have already alluded to in our chapter 

 on classification, pp. 171-177. 



Erichson, impressed by the variety existing in Neuroptera, 

 separated some of the groups into a sub- Order called Pseudo- 

 neuroptera ; this sub-Order comprised our Termitidae, Psocidae, 

 Ephemeridae, and Libellulidae. This division is still adopted in 

 several treatises ; the Pseudoneuroptera are indeed by some 

 naturalists retained as an Order distinct from both Orthoptera 



