INSECTS : WINGS AND THEIE APPENDAGES. 79 



those of the Machilis and Lepisma ; but, by the use of a 

 magnifying power of 600 diameters (as I have now put 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- 

 uninterrupted, 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 -0008 in length by -00085 in width, but 

 these are more dim and difficult to resolve. 



The beautiful and extensive order called Lepidoptera or 

 Scale-winged, par excellence, including the gay tribes of 

 Butterflies and Moths, present us with many exceedingly 

 interesting varieties in these singular coverings. The 

 study of these might be almost as wide as the immensity 

 of species ; I can show you only a few examples. 



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 legs are longer, and slenderer in propor- 

 tion ; 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. The scales proper are all 



* Mr. Kichard Beck, using illumination tinder a power of 1,300 dia- 

 meters, with the binocular microscope, has satisfied himself that the 

 markings of the Podura scale "consist of a series of toothed ridges, 

 the profile of which might be said to resemble the edge of a saw." He 

 believes that the markings on this and all similar scales are " more oi 

 less elevations or corrugations upon the surface, which serve the simple 

 purpose of giving strength to very delicate membranes." (See Quart. 

 Journ. Microsc. Sci. for 1862, p. 122.) This verdict, though diversely 

 expressed, does not importantly differ from my own judgment given 

 above. 



