84 



ETENIXGS AT THE MICE03C0PE. 



SCALES ON A GNAT S WING. 



marked on the upper membrane by five rows of minute 

 elevated warts, arranged obliquely -with one another. 

 From each of these warts springs a slender stem which 



gradually dilates into 

 a thin leaf-shaped 

 ])late of transparent 

 substance, having 

 from four to eio;ht or 

 ten longitudinal ribs. 

 They project in a radiating manner, all inclined towards 

 the tip of the wing. The same line on the under-sur- 

 face carries the like number of leaf-like plates, corre- 

 sponding in arrangement, structure, form and direction 

 with those on the upper side. The margins of the wing 

 all round are furnished with similar organs, with this 

 difference, that whereas the plates along the lines are 

 as it were cut off abruptly at their greatest diameter, 

 flie marginal ones converge again with a gracefully 

 curved outline, to a fine point : a form which is seen 

 to the greatest advantage along the hind edge of the 

 wing, while those of the front margin are thicker, and 

 more densely crowded. 



There are, however, other Insects which display these 

 or similar appendages in far greater profusion, and in 

 much variety of form and appearance. In the fissures 

 of cliffs that border the sea-shore may often be found 

 some wingless but active Insects, which are endowed 

 with the power of leaping in great perfection. From 

 their hinder extremity being furnished with long pro- 

 jecting bristles, they are sometimes called Bristle-tails, 

 but naturalists designate the genus Ifachilis. If you 

 can get one sufficiently still to examine it, you will be 

 delighted with the lustre of its clothing, which appears 



