ANT-LIONS, MAY-FLIES. 



37 



with two or three long, thread-like tails (fig. 37). When at rest 

 the wings are held together erect, the abdomen slightly curves and 

 the tails are directed upwards. 



The early stages of these insects are passed in the water. The 

 larvae vary greatly in form according to their habits, and they are 

 a considerable time arriving at maturity. In some cases this takes 



Fig. 37. 



Fig. 38. 



Nymph of Ephemera 

 vulgata. (HOU 



May-fly (Ephemera vulgata), enlarged. 

 (HOO.) 



more than one year. The mouth parts are well developed, the 

 mandibles in some cases being very large (1408). The abdomen 

 is furnished with complex tracheal gills. There are sometimes 

 leaf-like plates at the sides of the body (vibrated at frequent 

 intervals in the water), sometimes they are tassel-like or feathery 

 and are curved over the back. When the nymph (fig. 38) is full 



