386 ZOOLOGY. 



Order 2. Pauropoda. Microscopic ; body of six to nine segments 

 besides the head (Pauropus). 



Order 3. CJiilopoda. Sternum large, body flattened (Scolopendra, 

 Lithobius). 



SUB-CLASS III. Arachnida. Head and thorax intimately united ; no 

 antenna?, and only one pair of maxillae ; no genuine abdo- 

 minal legs. 



Order 1. Acarina. No thorax separate from the abdomen (Acarus, 

 Ixodes). 



Order 2. Pedipalpi. Maxillary palpi often ending in a forceps or 

 claw ; abdomen distinctly segmented (Scorpio, Chelifer, 

 Phalangium). 



Order 3. Araneina. Abdomen rounded, bearing two or three 

 pairs of spinnerets, and attached by a slender pedicel to the 

 thorax ; no metamorphosis (Epeira, Mygale). 



SUB-CLASS IV. Hexapoda. Antennae always present, and two pairs of 

 maxilte ; six thoracic legs ; a genuine metamorphosis. 



Order 1. Thysanura. Wingless, minute, with a spring, or ab- 

 domen ending in a pair of caudal stylets ; usually no 

 compound eyes ; no metamorphosis (Podura, Campodea, 

 Lepisma). 



Order 2. Neuroptera. Winged, net-veined, of equal size, pupa 

 often active ; abdomen often long and slender (Ephemera, 

 Libellula, Phryganea, Chrysopa, Perla, Termes). 



Order 3. Orthoptera. Wings net-veined ; fore-wings narrow, 

 straight, not often used in flight ; metamorphosis incomplete; 

 pupa active (Forncula, Locusta, Caloptenus, Phaneroptera, 

 Acheta). 



Order 4. 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). 



Order 5. 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 6. Diptera. Only two wings ; mouth-parts adapted for 

 lapping and sucking ; a complete metamorphosis (Musca, 

 CEstrus, Syrphus, Cecidomyia, Tipula, Culex). 



