293 [Packard. 



second and higher scries of suborders, the lowest wingless dipterous 

 Piilex assumes a much compactor, more cephalized form, while in the 

 wingless Chionea, which wonderfully mimics the higher Arachnids, 

 there is a still greater concentration of the arthromeres. This con- 

 centration of the body progresses towards a higher type in the de- 

 gradational forms of the Lepidoptera, such as the wingless females of 

 Orgyia, Anisopteryx, and liybernia. In ascending to the win^-less 

 hymenoptera, such as Pezomachus, Formica and Mutilla, there is 

 a closer 'approximation to the winged normal form of the sub- 

 order. While in the lower insects the loss of wings involves appar- 

 ently a total change in the form of the body, in the hymenoptera this 

 change is remarkably less than in any other insects, and the tri-partite 

 form of the insectean body is more strongly adhered to. 



Again, in the degradational winged forms of the hymenoptera, we 

 find the antennas rarely pectinated, a common occurrence in the lower 

 suborders ; also the Avings of the minute Proctotrupidre are rarely fis- 

 sured, and when this occurs they somewhat resemble those of Pteropho- 

 rus, the lowest Lepidoptera, and in but a single hymenopterous genus, 

 Anthophorabia, are the eyes in the male sex replaced by simple ocelli, 

 like those in Lepisma and other degradational forms of the lower 

 insects. 



What we know of the geological range of insects proves that the 

 hymenoptera were among the last to appear upon the earth's surface. 

 The researches of Messrs. Hartt and Scudder prove that the earliest 

 known forms of insects found in the Devonian rocks of New Bruns- 

 wick, were gigantic embryonic, and, in fine, degradational types of 

 Neuropterous and Orthopterous insects. The Coleoptera appear in the 

 Mesozoic rocks, where the lower Hymenoptera first appear in limited 

 numbers, including representatives of the Formicidaa and lower fam- 

 ilies, and with them the Lepidoptera and Diptera. 



We have throughout this article spoken of the Neuroptera as a 

 group, equivalent to the Orthoptera, or Hemiptera, or any other of 

 the suborders of insects. We believe thoroughly in the Neuroptera 

 as limited by the early entomologists. The Odonata are the types of 

 the suborder, and the Termitidw, Psocldse, Phryganeida?, Perlidte, 

 Ilemerobiidae, Slalidge, Panorpida?, Libellulidaj (Odonata), Ephemeri- 

 dae and Thysanura, are closely interdependent groups, and circum- 

 scribed by the most trenchant characters, which they possess in coiji- 

 mon, and which separate them from the closely allied Orthoptera, into 

 which, by modern German autliors especially, some of their families 

 appear to us to have been unwarrantably merged. 



The families of this suborder differ more among themselves than 

 those of other suborders, by reason of the lowness of their type, pre- 

 senting an unusual number of degradational forms, the connectiarr links 



