INTRODUCTION. 
57 
scales on both sides of the wings. When they are 
rubbed off, the wing is found to consist of an elastic 
membrane, thin and transparent, and marked with 
slightly indented lines, forming a kind of groove for 
the insertion of the scales. The latter are so mi- 
nute that they appear to the naked eye like powder 
or dust, and as they are very closely placed, their 
numbers on a single insect are astonishingly great. 
Leeuwenhoek counted upwards of 400,000 on the 
wings of the silk moth, an insect not above one- 
fourth of the size of some of our native butterflies. 
But how much inferior must this number be to that 
necessary to form a covering to some foreign butter- 
flies, the wings of which expand upwards of half a 
foot ; or certain species of Moths, some of which 
(such as the Atlas Moth of the east, or the Great 
Owl Moth of Brazil), sometimes measure nearly a 
foot across the wings ! A modern mosaic picture 
may contain 870 tesserulm, or separate pieces, in 
one square inch of surface; but the same extent of a 
butterfly’s wing sometimes consists of no fewer than 
100,736 ! 
In common with several other extensive races of 
insects, butterflies derive their nourishment entirely 
from liquid substances, and the structure of the 
mouth is consequently very different from that of the 
masticating kinds. They are hence classed among 
the haustellated or suctorial tribes of insects. The 
most conspicuous and elaborately constructed organ, 
is the long flexible tube projecting from the mouth, 
