The following classification is taken from Brauer (Systematisch Zool. Studien, SB. Akad. Wien, xci. Abth. 1, 1885). It is based upon recent advances in anatomy and embryology. Italics, etc. have been employed, and the mode of numbering the paragraphs altered. A small addition has also been introduced in Rhynchota (B. 8), and a slight change made in C. * Oligonephria, section b, in order to make it tally obviously with section a. The terms have been explained and used in the foregoing text.

I. Insecta After Ygogenea (= Collembola and Thysanura).

II. Insecta Pter Ygogenea.

A. Menognatha ametabola and hemimetabola.

* Polynephria .

(a.) genital orifices of the male, or of both sexes double; or single either by loss of one, or by the union of the two: ducts without chitinoid lining.

1. Ametabola

Wings very dissimilar; fore wings short, corneous; hind wings folded longitudinally and transversely. Antennae filiform; mouth-parts distinct. Dermaptera (Earwigs).

2. Hemimetabola

Larva aquatic; imago with wings never folded; hind wings the smaller or lost; antennae subulate; mouth-parts rudimentary. Ephemeridae (May flies).

(b.) genital orifice single; vasa deferentia and oviducts united to a common duct lined by chitin.

3. Hemimetabola

Larva aquatic; imago with sub-equal wings not folded, reticulate; antennae subulate; male copulatory organs remote from sexual aperture; prothorax small. Odonata (Dragon flies).

4. Hemimetabola Or Perennibranchiate

Larva aquatic; imago with hind wings often folded; longitudinal veins predominant; antennae filiform; prothorax broad; wings sometimes wanting. Plecoptera (=Perlariae or Orthoptera Amphi-biotica).

5. Ametabola

Very generally winged; hind wing dilated, folded longitudinally from the base, sometimes folded transversely; fore wings more or less coriaceous, reticulate, or modified in various ways. Orthoptera (Cockroaches, Leaf Insects, Walking Sticks, Grasshoppers, Crickets, Embidae ?).

* * Oligonephria .

6. Ametabola

Wings none, or four equal and caducous, or unequal similar, with either predominant longitudinal veins or areolate. Corrodentia (White Ants, Psocidae, Mallophaga=Bird-lice).

7. Ametabola

Wings four, fringed, very narrow, or wanting; antennae on the vertex; tarsal claws obsolete; mandibles setaceous. Thysanoptera (Thrips and its allies).

B. Menorliyncha ametabola and metabola1.

8. No Maxillary Palps

Labial palps transformed into a spurious labium, generally jointed; mandibles and maxillae setaceous, forming with the labium a sucking apparatus; wings either absent or four in number, similar or dissimilar, veined or areolate. Rhynchota (= Hemiptera), includes Ho?noptera with similar wings, \Cocadae, Aphidae, Cicadidae, etc., and Heteroptera with dissimilar wings, e. g. Bugs, Water Scorpions, etc, and the Lice or Pediculidae.

C. Menognatha and Metagnatha metabola.

Oligonephria

(a) wings alike, veined; or hind wings rudimentary or transformed or wanting: metathorax either equal to or less than mesothorax. = Petanoptera (Brauer).

i. Menognatha.

9. Wings, Four, Reticulate, Similar

Labial palps 3-jointed, joints free; maxillae free; pupa with distinct mandibles; larva Campodeiform, menognathous, or Ant-lionlike and metagnathous. Neuroperta (Megalopteray e. g. Ant-lion, Lace-winged Fly; Sialidae).

10. Wings, Four, Similar Or Absent

Labial palps 3-jointed, with basal joints connate; maxillae long, connate with the labium, with lobes free; pupa with distinct mandibles; larva eruciform. Panorpatae (Scorpion-flies).

11. Wings, Four, Similar, Subequal

Or the hind wings very often folded longitudinally from the base, the broader and with longitudinal veins predominant; mandibles rudimentary; maxillae connate with labium, all but lost; palps distinct or caducous; pupa with distinct mandibles; larva sub-eruciform. Trichoptera (Caddis-flies).

12. Wings, Four, Covered With Scales

Hind wings sometimes folded; fore wings rarely folded from the base (Pterophoridae); longitudinal veins predominant; mandibles lost, rarely distinct; galeae of maxillae forming the antlia; labial palps very generally of large size, free; pupa metagnathous, rarely mandibulate; larva mandibulate, eruciform. Lepidoptera (Butterflies, Moths).

13. Wings, Two, Hyaline

Never folded, with predominant longitudinal veins; hind wings transformed into halteres, very seldom lost; maxillary palps free or lost; labial palps transformed into a labella; hypopharynx setaceous; larva apodous or with false (i. e. secondary) feet; mandibulate or metagnathous; no labial palps; pupa metagnathous. Diptera (Two-winged Flies).

1 The male Coccidae alone are metabola.

14. Wings, None

Mandibles long, with serrated edges; maxilla short, with 4-jointed palp; labial palps 4-jointed, approximated at the base; labrum distinct; no hypopharynx; pupa metagnathous; larva apodous, mandibulate, with obsolete labial palps. Siphonaptera=- Aphaniptera (Fleas).

(b.) wings dissimilar, metathorax much larger than mesothorax.

15. Menognatha, Rarely Metagnatha

Fore wings coriaceous, rarely lost; hind wings membranous, folded longitudinally and often transversely, or wanting; longitudinal veins predominant; larva mandibulate, Campodeiform or eruciform, with or without legs; pupa mandibulate. Coleoptera (Beetles).

16. Menognatha And Metagnatha

Wings four, similar, membranous, very often areolate, or caducous, or absent; fore wings the larger; mesothorax the larger; pupa mandibulate, with maxillae sometimes transformed; larva mandibulate, eruciform, with or without legs. Hymenoptera (Gall-flies, Saw-flies, Ants, Bees, &c).

Note

The Sirepsiptera are included by Brauer and others among the Coleoptera. Prof. Westwood is still of opinion that they should be retained as a separate order. They are ento-parasitic on various Bees and Wasps. The male is free, has small twisted fore wings, longitudinally folded hind wings, and a large metathorax. It is metagnathous. The mandibles are reduced, the maxillae connate with the labium, their palpi 2-jointed. The female is blind, vermiform, and never quits the host. There is a dorsal canal, by which the male effects impregnation. The ova develope in the coelome; the Campodeiform larvae escape by the dorsal canal. They are carried by a Bee or Wasp to its nest, where they bore into a grub, and are transformed into apod vermiform larvae. The male pupa is coarctate (p. 153), and perforates one of the abdominal intersegmental membranes of the Bee pupa, protruding only the head, as does also the female. See von Siebold, A. N. ix. (I), 1843; Id. 'Paedogenesis,' Z. W. Z. xx. 1870.

See lit. pp. 146, 151, 156, 161.

Insecta Apterygogenea. See pp. 299-300. Ventral tube and copulation of Collembola, Reuter, Ent. Tidskr. i. 1880, and Zool. Record, 1884, Insecta, p. 277 ; cf. Lemoine, C. R. French Assoc, xi. 1882; development, Lemoine, op. cit. with lit. quoted.

Insecta Pterygogenea.

Ephemeridae, Eaton, Monograph, Tr. L. S. (2), iii. 1884-5; larvae, Vayssiere, A. Sc. N. (6), xiii. 1882; development of Chloeon, Lubbock, Tr. L. S. xxiv. 1864, xxv. 1866; vessels to caudal setae, Zimmermann, Z. W. Z. xxxiv. 1880.

Odonata: mouth-parts, Gerstaecker, 'Morph. Orthoptera Amphibiot.' Festschr. Natf. Freund. Berlin, 1873; larvae, Dufour, A. Sc. N. (3), xvii. 1852; of Aeschna grandis, Amans, Rev. des Sc. Nat. Montpellier (3), i.; tracheae of larva, Hagen Z. A. iii. 1880.

Plecoptera: Pteronarcys regalis, Newport, Tr. L. S. xx. 1851; Gerstaecker, op cit. under Odonata; Id. 'Vorkommen von Tracheenkieme, etc.' Z. W. Z. xxiv.

1874; Pteronarcys, Hagen, Stet. Ent. Zeitung, xxxviii. 1877; Perla maxima, Imhof, Inaug. diss. Aarau, 1881; Hermaphrodite Perla, O, Brandt, Z. A. i. 1878.

Orthoptera, cf. p. 146. Sound apparatus of Cricket, Pierce, Amer. Naturalist, xiii. 1879. Migratory Locust of Rocky Mountains, Riley, Packard, Thomas, Reports U. S. Entom. Commission, 1878, 1880; generative organs of class, Berlese, Atti Accad. Rom. (3), xi. 1882; Embidae, Hagen, Canad. Entom. xvii. 1885.

Corrodentia. Termitidae, F. Muller, J. Z. vii. 1873, ix. 1875; Hagen, Linnaea Entom. x. 1855, xii. 1858, xiv. i860; Id. Proc. Boston Soc. xix. 1878, xx. 1881; Hubbard, ibid. xix. Termes lucifugus, Lespes, A. Sc. N. (4), v. 1856. Infusorian parasites, Leidy, Journal Acad. Nat. Sci. Philadelphia, viii; Saville-Kent, A. N. H. (5), xv. 1885. Mallophaga, Grosse, Z. W. Z. xlii. 1885; Taschenberg, Nova Acta, 44, 1883; and Pediculidae, Piaget, 'Les Pediculines,' Leyden, 1880, Suppl. 1885; Giebel, 'Insecta Epizoa,' Leipzig, 1874. Psocidae, Kolbe, J. B., Zool. Sect. Westf. Vereins, 1879-80; Hagen, Psyche, hi. 1881; Id. Stet. Entom. Zeitung, xliii. 1882, xliv. 1883 (PI. in xliii); head, Burgess, Proc. Boston Soc. xix. 1878; Kolbe, Berlin Entom. Zeitung, xxviii. p. 177; sexual organs, dimorphism, Bertkau, A. N. 49 (1),

Thysanoptera, Heeger, SB. Akad. Wien, ix. 1852. Brit. Mus. Catalogues, 'Homoptera,' iv. 1852, p. 1049 et seqq., Pls. v.-viii.

Rhynchota; proboscis, Wilde, A. N. 51 (1), 1885; Witlaczil, Z. A. ix. 1886. Homoptera: Aphides, Buckton, Ray Soc. 4 vols. 1876-83; Lichenstein, 'Les Pucerons,' Montpellier, pt. i. 1885 (in progress); migrations, etc, Id. 'De Involution biol. des pucerons, et du Phylloxera en particulier,' Paris, 1883; Id. A. N. H. (5), iii, v, vi, viii, xi, xii, xiii, xiv, xv; Kessler, Nova Acta, xlvii. (3); dimorphism, Witlaczil, Dk. Akad. Wien, xlviii. 1884: cf. Buckton, op. cit. ii. p. 121, and A. N. H. (5), xv. p. 273; anatomy, Witlaczil, Arb. Zool. Inst. Wien, iv. 1882; development, Witlaczil, Z. W. Z. xl. 1884; Will, Arb. Zool. Zoot. Inst. Wurzburg, vi. 1883. Coccidae, Witlaczil, Z. W. Z. xliii. 1886. Comstock, Report Dep. Agric. U. S. A. 1880. O Aspidiotus Nerii, Schmidt, A. N. 51, (1), 1885. Psyllidae, Witlaczil, Z. W. Z. xlii. 1885; Low, Verhandl. z. b. Ges. Wien, xxxi. 1881; British sp., Scott, Entom. M. Mag. xix. 1882; Palaearctic, Low, op. cit. xxxii. 1882. Cicada, sound apparatus, Lloyd Morgan, Middlemis, Nature, xxxiii. 1885-6. Pelagic Hemiptera, Buchanan White, Challenger Reports, viii. 1883. Pediculidae: Phthirius, Graber, Z. W. Z. xxii. 1872; Haematopinus tenuirostris, Strobelt, A. N. H. (5), xi. 1883. See also 'Piaget' and 'Giebel' under Corrodentia Mallophaga.