202 INVERTEBRATE ZOOLOGY 
Order 6. Phalangida. Arachnids with extremely long, slender 
legs and a segmented abdomen. Ex. Phalangium. 
Order 7. Aranez. 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 
antenne. 
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 toa 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. 
