62 INTRODUCTION, 



tippet9. 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 tip. 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- 



