1 68 WM. A. KEPNER. 



is bathed in the suppurated mass. However, when about to 

 pupate the larva reverses its position with reference to the sup- 

 purated mass, and lies with its anterior end directed towards or 

 through the opening in the skin of the turtle. The larva is then 

 in a position to breathe air through the anterior stigmata. At 

 the same time the larva during the three or four days spent in 

 emerging from the host, frequently retreats into the excavated 

 cavity when disturbed, thus its anterior end may repeatedly be- 

 come contaminated with the bacteria of the suppurated mass. 

 I think, therefore, that the anterior stigmata are chiefly functional 

 during the two or three days spent by the larva in passing from 

 the turtle to the ground and that the reticulated plug is a bacterial 

 screen protecting the trachea from infection threatened by the 

 repeated retreat of the larva into the excavated cavity when it 

 lies with its posterior end at or within the suppurated mass. 

 If this conjecture concerning the time and character of the func- 

 tioning of the anterior stigmata is not warranted, I believe that 

 I am justified in agreeing with Hewitt ('08), that the anterior 

 stigmata of this character are functional at some stage in the 

 life of the larva. 



