1 
62 INTRODUCTION. 
tippets. The scutellum — a triangular piece in the 
hinder part of the thorax, which is very conspicuous 
in beetles and many other tribes — likewise exists in 
butterflies, but it is very minute, and has its point 
directed forwards. The thorax is always shorter 
than the abdomen, and generally more robust, as it 
supports all the organs of motion, and contains the 
muscles by which the latter are actuated. 
These important appendages are of course the 
wings and legs, of which it is necessary to give some 
account. The latter, as in all other genuine insects, 
are six in number, and composed of the same amount 
of pieces as in most of the class. They are inserted 
pretty close to each other, without any inequality in 
the size of the intervening spaces. The thigh is of- 
ten fringed with long hairs, and the tibia is frequent- 
ly armed with a spur near the middle, and two others 
at the lip. The tarsi in all the perfect legs are five- 
jointed, and furnished with two claws at the extre- 
mity, which are often bifid. (PI. I. fig. 13.) Many 
of these insects, however, have the anterior pair of 
legs imperfect, or not adapted for walking, being too 
short to reach the plane of position, and usually 
drawn close to the sides of the thorax, the long hairs 
of which in a great measure conceal them from our 
view. These spurious legs have only one joint in 
the tarsus, which, in some cases (as in Vanessa, &c.), 
is without claws ; and the species so circumstanced 
are named tetrapod, or four-footed butterflies. 
The wings are of much greater extent, in propor- 
