330 



Aquatic ' Societies 



here apparent. They rest like long out-riggers radiately 

 arranged upon the surface, easily supporting her weight 

 while she liberates the egg mass and lets it down into 

 the water. At the top of the egg clump appears a cir- 

 cular transparent disc from which the egg mass depends. 

 This disc catches upon the surface film, tho pulled 

 down into it in a little rounded pit-like depression 

 by the weight of the eggs. Slowly 

 the eggs descend pulling out the gelatin 

 attaching them to the disc into a slender 

 thread that thus becomes stretched to 

 a length of several inches. The female 

 flies away to the shore and leaves them 

 so. Then they drift about like floating 

 mines, transported by breezes and cur- 

 rents. This little disc of gelatin dimp- 

 ling the surface film is indeed a frail 



FIG. 194. The egg-laying of Chironomus meridionalis. 



A, The female at rest extruding the egg-mass. 



B, The female resting on the surface film, letting the egg mass down into the water. 



C and D, The egg mass liberated and hanging suspended from the surface film by a delicate 

 gelatinous cord attached to a small disc-like float. 



bark for their transportation. When driven by waves 

 and currents, they break their slender moorings and 

 settle to the bottom, or adhere to floating stems 

 against which they are tossed. 



There is another phenomenon of the water surface so 

 curious and interesting it merits passing mention here. 

 There is a black wasp Priocnemis flavicornis, occasion- 

 ally seen on Fall Creek at the Cornell Biological Field 



