384 CHRISTINE ESSENBERG 



rounding gluing substance is very plainly seen. The eggs are 

 beautifully white, elongated, and cylindrical, with the attached 

 side slightly flattened. The chorion is decorated with small 

 depressions. The eggs of Notoneda insulata are about two 

 mm. long. Those of smaller species are slightly smaller in size. 

 After an incubation period of twenty days, the chorion splits 

 at the anterior end and the nymph crawls out. In working 

 out from the envelope the nymph first gets its head out, con- 

 tracting and expanding the body and bending over it pulls itself 

 out of the case, sometimes stopping to rest, then continuing the 

 process again. Inside the coarse egg envelope and surrounding 

 the nymph is a thin transparent membrane which occasionally 

 breaks, allowing the animal to escape while the membrane 

 remains attached to the outer envelope, but often the nymph 

 is still surrounded by the membrane after leaving the egg-case 

 and must work its way out from it. As soon as the nymph is 

 free it goes to the bottom and rests a while and then begins 

 to move about actively, searching for food. The nymphs are 

 very beautiful, with large compound eyes which are conspicu- 

 ously red. The body is transparent white. The long hairs are 

 well developed on the lateral margins and over the pleura, 

 which are shallower than in the adult; the hairs on the middle 

 carina are short and irregular. After from seven to ten days 

 the first moult takes place. Hoppe states that there are five 

 complete series of moultings in Notoneda glauca, and J. R. 

 de la Torre, Bueno, thinks that there are about five moultings 

 in all the species. I have not been able to follow the complete 

 series of moultings, because it is extremely difficult to raise 

 nymphs in an aquarium owing to the fact that they attack one 

 another even in the presence of an abundance of food. They 

 are very sensitive to foul air and contaminated water. The 

 nymphs differ from adults in their behavior in that they come 

 more frequently to the surface, about once in every three or 

 five minutes, and the fringes are usually flapped back, while 

 in the adult the fringes are lifted only when the insect is in 

 great need of oxygen. 



The food of Notonectas consist of animal matter, chiefly, 

 living or dead insects, but they do not hesitate to attack other 

 animals. Thus Bueno has observed the nymphs of Notoneda 



