2. _Pseudoneuroptera_.—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. _Neuroptera 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. 11. 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 Phasmidae 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.