366 ZOOLOGY. 
Order 8. Orthoptera.—Wings net-veined; fore-wings narrow, 
straight, not often used in flight; metamorphosis incom- 
plete; pupa active (Caloptenus, Locusta, Phaneroptera, 
Acheta). 
Order 4. Platyptera.—Body usually flattened; pronotum usually 
large and square; often wingless (Mallophaga or bird-lice, 
Perla, Psocus, white ants). 
Order 5. Odonata.—Prothorax small; thorax spherical; both pairs 
_-- of wings of nearly the same size, net-veined. Larva and 
pupa aquatic; labium forming a large mask (Agrion, Libel- 
lula). ; 
Order 6. Plectoptera.—Mouth-parts nearly obsolete; wings net- 
veined, hinder pair small, sometimes wanting; abdomen 
ending in three filaments. Larvee aquatic, with large jaws, 
and with gills on the side of the hind body (Ephemera). 
Order 7. Thysanoptera.—Mouth-parts forming a short conical 
sucker; palpi present; wings narrow, fringed; abdomen end- 
ing in a long ovipositor (Thrips). 
Order 8. Hemiptera.—Mouth-parts forming a sucking beak; pro- 
thorax usually large; fore-wings often thickened at base; 
pupa active (Coreus, Arma, Pentatoma, Cicada, Coccus, 
Aphis). 
Serres II. Metabola, or with a complete metamorphosis, 
Order 9. Neuroptera.—Wings net-veined; mouth-parts free, 
adapted for biting; ligula large, rounded; prothorax large, 
square. Larve often aquatic (Corydalus, Chrysopa, Myr- 
meleon) 
Order 10. Mecoptera.—Wings somewhat net-veined, or absent. 
Larve like caterpillars (Panorpa, Boreus). 
Order 11. Trichoptera.—Wings and body like those of moths; 
mandibles obsolete in imago. Larve usually aquatic, liv- 
ing in cases (Phryganea). 
Order 12. Coleoptera,—Fore-wings thick, ensheathing the hinder 
pair, which are alone used in flight; mouth-parts free, 
adapted for biting; metamorphosis complete (Doryphora, 
Clytus, Lucanus, Harpalus, Cicindela). 
Order 18. Siphonaptera.— Wingless; mouth-parts adapted for 
sucking.’ Larva maggot-like, but with a well-developed 
head and mouth-parts (Pulex). 
Order 14. Diptera.—But one pair of wings; mouth-parts adapted ~ 
' for lapping and sucking; a complete metamorphosis (Musca, 
Cstrus, Syrphus, Cecidomyia, Tipula, Culex). 
