kellogg] THE COLORS OF JWTTERFLIES AND MOTHS 207 



butterflies, many new shapes will be found. But through all this 

 diversity of appearance, a fundamental plan of make-up may be 

 recognized in each of these minute structures. Most commonly the 

 scales are more or less ovate in outline with the little stem projecting 

 from the narrower end. The broader end has its margin entire or 

 with dentations of varying depth and number. These dentations may 

 be so deep that the scale looks like a several-fingered little hand. In 

 size the scales vary from .07 mm. (^ (1 inch) to .8 mm. (J |T inch) if 

 we exclude the long hair-like forms common near the base of each 

 wing, and also the slender elongate ones which project from the wing- 

 margins. In width the scales vary from hair-like to a breadth of .4 

 mm. (J* inch). Some scales are as broad as long, or even broader 

 than long. Running longitudinally from base to outer margin are 

 many fine little subparallel lines or striae. These striae vary in dis- 

 tance apart, on different scales, from .0007 mm., as in the scales of 

 the great blue Morpho butterflies, to .004 mm., as in the sulphur- 

 yellow butterfly, Catopsila eubule. 



The scales cover the wings on both upper and lower sides (in all 

 but a few "clear-winged" moths), being insecurely attached to the 

 wing membrane by having their short pedicels inserted in little 

 pockets or cups on the wing surface. They show an interesting and 

 varying manner of arrangement which varies from an extremely 

 uniform one in butterflies and higher moths to one of much less 

 regularity of disposition in lower moths. On the wings of a butterfly 

 the scales are inserted with their pedicels directed toward the base of 

 the wing in subparallel rows running transversely across the wing, 

 i. e., from anterior to posterior margin, and the scales in each row 

 are at approximately equal distances apart. Their distance is less 

 than the width of each scale, so that adjoining scales overlap laterally 

 and thus make each row to be composed of two tiers of scales, an 

 upper and an under one ; the insertion-cups of one tier are very 

 slightly but perceptibly advanced beyond those of the other tier- 

 The scales of the upper tier alternate with those of the lower tier, and 

 each upper scale overlaps laterally two under ones. But in addition 

 to this lateral overlapping, the distance between the rows of insertion- 

 cups is less than the length of the scales, so that there is an overlapping 

 of the tip of the scales of one row over the bases of the scales in the 

 next row in front. By this double overlapping there is formed a 

 complete shingled covering of scales over each surface (upper and 

 under) of each wing. This close placing and overlapping, and the 



