OR, PLATtf TEACHING. 



33 



pair of wings 6, second pair of 

 wings 7. The thorax 2, is di- 

 vided into three segments : the 

 pro-thorax 10, the meso -thorax 11, 

 the meta-thorax 12. 



Insects, when mature, have 

 tf^ra? pairs of Ze?ys, and to each 

 leg a kind of foot. The legs f2 

 are of various forms, but A 

 generally consist of the fe- 

 mur or thigh, 13, the tibia 

 or leg, 14, and the tarsus 

 or foot, 15. Their antennce 

 are of various forms. Some- 

 times they have a club-like 183, 

 head, with a knob at the extre- 

 mity, 16. Sometimes they are 



184. 



featheted 17, saw-like 18, toothed 

 19, ^iry 20, or curled, 4-181. The 

 uses of their antennce are to feel 

 objects, and they are supposed 

 to be also organs of hearing. 



The mouths of insects consist 

 either of mandibles or jaws, 1, or 



1 



185. 



suckers, 2 ; they have also tongues 

 3, forceps 4, and other minute 

 parts. The mandibles are for the 

 purpose of biting, cutting, and 

 gnawing ; the suckers for drawing 

 2* 



through their tubes juices from 

 the internal parts of flowers and 

 from deep recesses ; the tongues 



are for licking the juices of plants ; 

 and the forceps are for seizing and 

 holding prey, and for defence. 

 The eyes of insects are not move- 

 able, but are either simple, 5, or 

 compound, 6 ; both are ^ 

 generally present in an ^ 

 insect. The simple eyes, © @ 

 called stennata, 5, are £ 

 usually three, and are 

 placed so as to form 

 three points of a triangle 

 on the top of the head. 

 These are used in look- 

 ing upwards. The compound 

 eyes, 6, are generally two, one on 

 either side of the head. 

 JtjL Each hexagon, 7, is a 

 fftflf perfect eye, having a 

 nerve, retina, lens, iris, 

 an&pupil. Inthehouse- 

 I88, fly there are 4000 of 

 these hexagons,ov ocelli, 7, making 

 up one compound eye or oculus, 

 6. In some dragon-flies there 

 are 12,000; butterflies 17,000; 

 beetles 25,000. Insects possess 

 the faculties of taste and smell, 

 and find their favourite flowers 

 or food by peculiar odours. 

 Their wings usually consist of a 

 fine double membrane, 8, sup- 

 ported by nervures, forming an 

 inner frame-ivork, 9. The wings 



