194 CATERPILLARS AND THEIR MOTHS 



was free from the skin it began to settle into shape, 

 contracting the abdomen and drawing the head and 

 shoulders back into line with the rest of the body. 

 From some hidden source a fluid oozed under the 

 wing-cases, between them and the body, and often a 

 little way beyond their edges. This fluid hardened 

 into a thin membrane similar to that over the whole 

 pupa, but not as firm and stiff. We had seen this 

 membrane when moths emerged from their pupa-skins, 

 but had not known how it was formed. Probably it 

 exists in many, if not all, pupae, but we have not ex- 

 amined more than five or six. All of these had the 

 membrane. In some of the attacine pupae it was very 

 easy to see as the moths emerged. 



