EXPLANATION OF PLATE Ia. 



A fore wing of Pygcera anachoreta and a hind wing of Thais 

 polyxena at a certain stage of pupal development. 



They both show the marginal trachea (Poulton's line), the portion 

 of the wing tissue beyond this, and the ciHa, which arise chiefly 

 from the area outside the marginal trachea. 



In T. polyxena, the marginal trachea is seen to be slightly out of 

 position at two points. A result either of injury in mounting, or to 

 some contraction occurring after mounting the specimen. 



