202 INVERTEBRATE ZOOLOGY 



Order 6. Phalangida. Arachnids with extremely long, slender 

 legs and a segmented abdomen. Ex. Phalangium. 



Order 7. Aranese. Spiders. Arachnids with a constriction between 

 the cephalothorax and the unsegmented abdomen. Ex. Agelena. 



Order 8. Acarina. Mites. Arachnids with body not divided into 

 cephalothorax and abdomen, and unsegmented. Ex. Hydrachna. 



Order 9. Linguatulida. Parasitic arachnids with ringed, vermi- 

 form body. Ex. Pentastomum. 



Order 10. Tardigradi. Minute, aquatic arachnids. Ex. Macrobiotus. 



Order 11. Pycnogonida. Sea spiders. Marine arachnids with very 

 long legs. Ex. Pallene. 



Class 3. Tracheata. Air-breathing arthropods with one pair of 

 antennae. 



Division 1. Onychophora. Worm-like tracheates with indistinctly 

 segmented body and appendages. Ex. Peripatus. 



Division 2. Myriapoda. Worm-like tracheates with distinctly 

 segmented body and appendages. 



Order 1. Progoneata. Body mostly cylindrical and with two pairs 

 of legs to a segment. Ex. Julus. 



Order 2. Chilopoda. Centipeds. Flattened myriapods with one 

 pair of legs to a segment. Ex. Lithobius. 



Division 3. Insecta. Insects. Tracheates with body divided into 

 head, thorax, and abdomen ; with three pairs of legs and usually two 

 pairs of wings. 



Order 1. Thysanura. Minute, wingless insects without metamor- 

 phosis. Ex. Lepisma. 



Order 2. Pseudoneuroptera. Insects with two pairs of net-veined 

 wings, biting mouth-parts, and incomplete metamorphosis. Ex. 

 Dragon fly. 



Order 3. Orthoptera. Insects with two pairs of wings (the first 

 pair being usually parchment-like), biting mouth-parts, and incom- 

 plete metamorphosis. Ex. Grasshopper. 



Order 4. Neuroptera. Insects with two pairs of net-veined wings, 

 biting mouth-parts, and complete metamorphosis. Ex. Ant lion. 



Order 5. Coleoptera. Beetles. Insects with two pairs of wings 

 (of which the first pair are elytra), biting mouth-parts, and complete 

 metamorphosis. Ex. Potato beetle. 



