INSECTS. 



155 



one thousand and eighty steps ! This, according to the 

 calculation of Kirby and Spcnce, is as if a man whose 

 steps measured only two feet, should run at the incredible 

 rate of twenty miles in a minute. 



Every one has had occasion to observe, not always 

 without an emotion of anger, the leaping powers of the 

 Flea (Pulex irrhans). A bound of two hundred times its 

 own length is a common feat ; as if a man should jump 

 twelve hundred feet, or a quarter of a mile ! What a pity 

 that Insects were not allowed to be competitors in the 

 athletic games of old ! 



With regard to their organisation, all Insects in the 

 mature state are armed with three pairs of legs • which 

 are divided into several parts, as, the hip, the thigh, the 

 shank, and the foot, by distinct hinge-joints : the foot 

 itself (tarsus) consists of several jointed pieces, and is 

 usually terminated by two hooks, and often furnished with 

 adhesive pads, or other organs accessory to locomotion. 

 In most of the tribes there are also wings, two pairs in 

 general (but in one extensive Order the hinder pair is 

 obliterated) ; each of these organs consists of two films of 

 highly elastic membrane, stretched over a frame-work of 

 strong tubes, as the silk of an umbrella is expanded over 

 its ribs. In the Order Coleoptera (Beetles), the fore pair 

 are thick, leathery, and opaque, chiefly serving as shields 

 to protect the hind pair in repose ; and in some other 

 Orders they are somewhat coriaceous ; while in the beau- 

 tiful Lepidoptera (Butterflies), the transparency of both 

 pairs is concealed by a covering of minute feather-like 

 scales, overlapping each other, reflecting various colours, 

 and arranged in a mosaic of inimitable beauty. 



