394 INSECT TRANSFORMATIONS. 



the spring in the tail, by means of which it leaps, 

 jerking it downwards and outwards from its body as 

 the flea does its legs. 



Leaping position of the velvet spring-tail, magnified, 



Amongst the insects which spring upon their prey 

 like the cat and the lion, the most commonly observed 

 is the little hunting spider (Salticus scenicus), whose 

 zebra stripes of white and brown render it easily- 

 discovered on our window-frames and palings.* 

 But all the spiders even those which form webs - 

 are accustomed to spring in a similar way upon what 

 they have caught ; and when we are told of the 

 gigantic American one (My gale avicularia), which 

 even makes prey of small birds (Trochilidce}, the 

 necessity of extraordinary agility must be obvious ; 

 for these tiny birds are described to move with 

 almost the velocity of light, the eye, notwithstand- 

 ing the brilliancy of their metallic colours, being 

 frequently baffled in tracking their flight. The 

 spider itself, however, being three inches in length, 

 one and a half in breadth, and eleven inches in the 

 expansion of its legs, is little less than the bird upon 

 which it pounces, as may be seen from the following 

 figure, taken from the splendid work of Madame 

 Merian upon the insects of Surinam. 



All animals which fly are furnished with powerful 

 muscles for moving their wings, in the same way as 

 the limbs of those which leap are similarly provided; 



* See Insect Architecture, p. 355. 



