64 THE BUTTERFLY. 



pair of legs, often as large as the others [Fig. 



72]. The middle and hinder segments together 



form a compact vaulted oval mass, wholly con- 

 cealed by scales and hairs, but di- 

 vided by a number of sutures into 

 the many parts which form the seg- 

 ments of the thorax. The middle 

 segment, moreover, is developed to 

 PIG. 72. -Pro- a ^ ar larger extent than the hind- 



ofSfso a thorai 01 of most, in order to carry the front 



Vanessa Atalanta, . , . _ ,,. , , 



with scales remov- wings, which during night are 

 obliged to meet in great measure 

 the resistance of the wind, and are therefore fur- 

 nished with more muscles. 



The appendages of the thorax are the legs, 

 wings, and shoulder lappets. As in the earlier 

 stages, a pair of legs is attached to each segment, 

 but these legs are very different from the old ap- 

 pendages ; they are now mere sticks, each divided 

 into five principal pieces, called coxa, trochanter, 

 femur, tibia, and tarsus. The coxae or haunches 

 are often prominent, having the shape of pyra- 

 midal stems, more than half consolidated with 

 the body and with each other, extending ob- 

 liquely downward and backward, and forming in 

 this way a strong support to the hinder part of 

 the thorax, which is the real centre of gravity of 

 the body. The trochanter is only a short joint 

 between the haunches and the thighs, carrying the 



