CLASSIFICATION 27 



Order g. Dip'tera (two-winged) : Forms with only one pair of 

 wings and behind them a pair of short-knobbed processes, 

 the halteres. Flies and mosquitoes. 



Order h. Coleop'tera (shield-winged) : Forms with a pair of horny 

 wing covers and a single pair of membranous wings. Beetles. 

 Order i. Hymenop'tera (membrane-winged) : Forms with two 

 pairs of membranous wings, mouth parts for both biting and 

 sucking, and the female usually with a sting, pierce, or saw. 

 Ants, bees, wasps (Figs. 32, 36). 



SUBKINGDOM XII. PHOTO CHORD A'TA (first cord) : Marine animals 

 forming a connecting link between the ver- 

 tebrates and invertebrates. Sea-squirts, 

 lancelet. 



SUBKINGDOM XIII. VERTEBRA'TA (turning) : Forms with a skele- 

 tal axis and a dorsal nerve cord whose an- 

 terior end is dilated into a brain. 

 Class 1. Pisces (fish) : Aquatic cold-blooded forms with gills and 



usually paired fins, but not legs. 



Class 2. Amphib'ia (both lives): Cold-blooded forms without 

 scales, usually with two pairs of legs, and breathing by gills in 

 early life. Frogs, salamanders, toads (Figs. 230, 231). 

 Class 3. Reptll'ia (to creep): Cold-blooded forms with scales 



and lungs. Snakes, lizards, turtles. 



Class 4. A'ves (birds) : Warm-blooded vertebrates with feathers. 

 Class 5. Mamma'lia (with breasts) : Hairy vertebrates suckling 

 their young. Dog, monkeys, man. 

 Order a. Monotre'mata (single opening) : Egg-laying mammals. 



Duck mole, spiny ant-eater (Figs. 297, 300). 

 Order b. Marsupia'lia (pouch) : Mammals whose young at 

 birth are very small and immature and are therefore placed 

 in an abdominal pouch to be nourished several weeks. 

 Opossums, kangaroos (Figs. 299, 298). 

 Order c. Insectlv'ora (insect eaters) : Mammals living largely on 



insects. Shrews, moles (Fig. 311). 



Order d. Edenta'ta (without teeth) : Forms in which the teeth 

 are often wanting and if present there is no enamel. Sloths, 

 ant-eaters. 



