VIII MAY-FLIES 327 



long anchoring threads attached to the eggs of 

 Ephemera vulgata. From 8 to 12 of these are fixed 

 to a zone which encircles the egg transversely towards 

 one end. The whole arrangement is repeated at the 

 other end of the egg. Each thread bears a small 

 knob at its free end, and these knobs apparently 

 become entangled at the bottom of the stream and 

 moor the eggs. 



