136 ARTHROPODA. 



Order 3. Diplopoda. 



With numerous trunk segments, each with two 

 pairs of legs. No poison jaws. Body not com- 

 pressed. (Julus.) 



Order 4. Pauropoda. 



With ten trunk segments and nine pairs of legs. 

 (Pauropus.) 

 CLASS 5. Insecta. 



Body divided into head, thorax, and abdomen. 

 Three pairs of thoracic legs and generally one or 

 two pairs of wings. 



Order 1. Thysanura. 



No metamorphosis. No wings. Mouth-parts 

 usually mandibulate. Some forms show vestigial 

 abdominal appendages. (Lepisma, Sminthurus.) 



Order 2. Orthoptera. 



Metamorphosis direct. Two pairs of wings usu- 

 ally present, of which the anterior are usually 

 tough and protect the more delicate posterior 

 ones. Mouth-parts mandibulate. (Acridium, 

 Gryllus, Periplaneta.) 



Order 3. Neuroptera. 



Metamorphosis direct. Two pairs of netted 

 veined wings usually present. Mouth-parts man- 

 dibulate. Prothorax free. (Libellula, Termes, 

 Hexagenia.) 



Order 4. Hemiptera. 



Metamorphosis direct. Two pairs of wings 

 usually present. Mouth-parts piercing and 

 suctorial. (Benacus, Cicada, Pediculus, Aphis.) 



Order 5. Diptera. 



Metamorphosis indirect. Wings, when present, 

 one pair and membranous. Mouth-parts sucto- 

 rial. (Culex, Tabanus, Musca.) 



Order 6. Lepidoptera. 



Metamorphosis indirect. Two pairs of scaly 

 wings. Mouth-parts suctorial. (Platysamia, 

 Anosia, Philampelus.) 



Order 7. Coleoptera. 



Metamorphosis indirect. Membranous hind 

 wings folded and covered by modified fore 

 wings, the elytra. Mouth-parts mandibulate. 

 (Lachnosterna, Doryphora.) 



