VIII LARVA AND NYMPH 113 



attaching the abdomen to the thorax. At last its 

 efforts are crowned with success, and after half an 

 hour of these rough gymnastics the sheath, pulled in 

 every direction, ruptures at the neck, at the insertion 

 of the feet and petiole, and, in short, wherever the body 

 has been movable enough to allow of sufficiently 

 violent displacement. 



All these tears leave several irregular strips, the 

 chief of which envelops the abdomen and comes 

 up the back of the thorax. To it belong the 

 wing sheaths. A second strip covers the head. 

 Lastly, each foot has its own sheath, more or less 

 dilapidated toward the base. The biggest, which 

 forms the chief part of the whole covering, is got 

 off by alternate dilatations and contractions of the 

 abdomen, which gradually push it back into a little 

 ball connected for some time with the animal by 

 tracheal filaments. Then the Sphex again becomes 

 motionless, and the operation is over, though head, 

 antennae, and feet are still more or less covered. 

 It is clear that the feet cannot be freed in one 

 piece on account of the roughnesses and thorns with 

 which they are armed. These rags of skin dry up 

 and are got rid of later by rubbing the feet together, 

 and by brushing, smoothing, and combing the whole 

 body with the tarsi when the Sphex has acquired 

 full vigour. 



The way in which the wings come out of their 

 sheaths is the most remarkable feature in this casting 

 of the skin. In their undeveloped state they are 

 folded lengthways and much contracted. A little 

 while before they acquire their normal appearance 

 one can easily draw them out of their sheaths ; 



I 



