$16 MODERN CLASSIFICATION OF INSECTS. 
4.00,000 on the wings of the silkworm moth according to Leuwenhoeck : 
in some species, however, the wings are partially, or even entirely, 
denuded of scales ; and in others, small patches only are thus denuded, 
as in the great atlas moth. In many species, these scales exhibit the 
most brilliant metallic tints, so that in the bright light of the sun it is 
almost impossible to look upon them: such is especially the case with 
the splendid blue Brazilian species of Morpho: others, again, have 
the under side of the wings ornamented with beautiful silvery spots, 
occasioned, according to Kirby and Spence (Jntérod. vol. iii. p. 652.), 
by the high polish of their surface, and the purity of the white colour 
of the scales, contrasted with the dull opake colour of the wings. It is 
only very recently that the surface of these scales has been microscopi- 
cally examined with the view of ascertaining the mode in which the beau- 
tiful colours which they exhibit is produced. M. Bernard Deschamps 
has especially investigated these parts, which he has found to differ, 
not only in the granulations and striz with which their surface is co- 
vered, but also in the number of the membranes of which they are 
composed, having arrived at a knowledge of the latter curious circum- 
stance, from the scales being occasionally imperfect in certain parts, 
giving an opportunity of investigating them more perfectly than when 
entire: hence he is induced to consider that all these scales are 
formed of two or more commonly, of three lamella ; and it is always 
upon the superior layer that the granulations, of which the colouring 
matter of the scale is composed, are to be found : these granulations 
are of a regular form, and their number is sometimes so considerable, 
that the scale is entirely opake; when it exhibits striz, it is always 
upon the second lamella that they are placed. These striz are often 
parallel, and formed of rows of minute granulations, like oval or round 
pearls placed endto end. Those scales which have striz without 
granulations, have only two lamellz ; the inferior surface of the se- 
cond (when only two), or the third lamella in almost all the diurnal, 
and some nocturnal species, has the property to reflect prismatic 
colours more intense and beautiful than those on the upper surface, 
which give the colour to the wing. The scales which ornament the 
splendid metallic blue and green butterflies have the surface differ- 
ently constructed from those of any of the others. M. Deschamps has 
also described some singularly formed scales, peculiar to the males of 
certain species of butterflies, which he terms “ plumules.” The species 
which possess them belong to the genera Pontia, Hipparchia, and 
