INSECTS. 
155 
one thousand and eighty steps ! This, according to the 
calculation of Kirby and Spence, 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 irritans'). 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 arc 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 arc 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 arc somewhat coriaceous ; while in the beau- 
tiful Lepidoptera (Butterflies), the transparency of both 
pairs is concealed by a covering of minute featlier-like 
scales, overlapping each other, reflecting various colours, 
and arranged in a mosaic of inimitable beauty. 
