88 EVEXINGS AT THE MICEOSCOPE. 



discern the character of their markings, is a proof of 

 the good definition of mj microscope ; this is what 

 is called a ' test-object." At first sight they seem 

 covered with ribs like those of the Machilis and Lepis- 

 m.a ', but, by the use of a magnifying power of 600 diam- 

 eters (as I have now pnt on), you perceive that, in 

 the first place, the lines are not straight nor parallel, 

 but curve irregularly, and are often branched ; and, 

 in the second place, that they are not iminterrupted, 

 but made up of a series of successive wedge-shaped 

 warts, which lie nearly flat, but project a little at the 

 larger end, where each overlaps the next. The scale 

 we are looking at measures '0014 inch in length, and 

 •0009 in width ; here the marks are well defined ; here 

 are smaller scales -OOOS in length by -00035 in width, 

 but these are more dim and difiicult to resolve. 



Tlie beautiful and extensive order called Lepidoptera 

 or Scale-winged, par excellence^ including the gay tribes 

 of Butterflies and Moths, present us with many ex- 

 ceedingly interesting varieties in these singular cover- 

 ings. The study of these might be almost as wide as 

 the immensity of species ; I can only show you a few 

 cxmples. 



Here are specimens from the pretty little white 

 Five-plume Moth {Pterophorus), so common in meadows 

 in summer. The general shape of the scales from the 

 body and wings is that of a willow-leaf, some singly 

 pointed, but more cut at the tip into two, three, or 

 four notches. Those from the leo;s are lonorer and slen- 

 derer in proportion ; and among the others from the 

 wings, there are some which take the form of hairs, 

 which send forth one or more branches from one side, 

 that form a very acute angle with the main stem. Tlio 



