PLATE XXI. 
Fig. 1. Two eggs of Notonecta undulata after hatching, showing the 
characteristic slit in the shell and the clear embryonic membrance shed 
by the nymph upon emerging. 
Fig. 2. Adult Notonecta undulata in the water. 
Fig. 3. Egg nearly ready to hatch. Note the red eye spot and the 
dark line at margin of the gelatinous substance which glues the egg to 
its support. 
Fig. 4. A freshly laid egg viewed from above. 
Fig. 5. A roadside pool in early spring. The back-swimmers were 
arriving in numbers, flying from some unknown quarters where they 
had passed the winter. 
Fic. 6. Eggs of Notonecta undulata, freshly laid upon old weed stems 
lodged in the waters of the pool. Gyrinid beetles lay somewhat similar 
eggs, which may be distinguished by their arrangement upon their sup- 
port and by the fact that the eye spots in advanced eggs are black 
instead of red, and farther from the end of the egg than in those of the ~ 
back-swimmers. Plate first used in Ento. News, XXVIII. 
(508) 
man me 
Se ey ee Pay ee 
eli th eat 
i © 
i iy eee ee 
at A ae) CO Ei sas 
