We must again ask the reader to bear in mind that numerous exceptions exist to these characters in most of the great Orders; for instance, wingless forms are not by any means rare in several of the Orders.
Before remarking further on this system we will briefly sketch two other arrangements of the Orders of Insects, for which we are indebted to Packard and Brauer.
Packard's Classification.
Packard has devoted much attention to the subject, and has published two or three successive schemes, of which the following is the most recent:[[109]] the definitions are those of the author himself, but the information in brackets is given to institute a concordance with the system we adopt:—
1. Thysanura. Wingless; often with a spring (equivalent to our Aptera).
2. Dermaptera. Front wings minute, elytra-like (= Forficulidae, a part of our Orthoptera).
3. Orthoptera. Wings net-veined; fore wings narrow, hind wings folded (= our Orthoptera after subtraction of Dermaptera).
4. Platyptera. Four net-veined wings; mouth parts adapted for biting (= Termitidae and Mallophaga, parts of our Neuroptera).
5. Odonata. Wings net-veined, equal (= Odonata, a division of our Neuroptera).
6. Plectoptera. Wings net-veined, unequal (= Ephemeridae, a part of our Neuroptera).