180 THE UNIVERSITY SCIENCE BULLETIN. 
adult at all, but is more akin to that of Corixa, and the entire form of the © 
insect in these stages is very different from that of the adult.” : 
The above was written in 1897. Little more kas been added since that 
time, due to the difficulty of keeping the nymphs alive under laboratory ~ 
conditions. Bueno, 1905, reported his failure to get them beyond the ~ 
second or third instar. 
Hoppe, 1912, in his paper on “Die Atmung von Notonecta glauca,” — 
makes a few remarks on the life history, noting five nymphal instars. 
The writer, 1917, published an account of the biology of Notonecta — 
undulata, and during the year 1917 was able to study the biology of three — 
other species, N. variabilis, N. insulata, and N. irorata, which are found — 
in the waters about Ithaca, N. Y. The experience gained in studying — 
the behavior of N. undulata was found useful in bringing these species — 
through their transformations. 
The behavior of the back-swimmers, especially with reference to — 
respiration, has been quite fully treated, though even here there are 
problems as yet unsolved. 
Brocher, 1909 and 1913, and Hoppe, 1912, have made extended studies 
on the respiration of N. glauca and Christine Essenberg, 1915, of Berke- 
ley, Cal., has written upon the behavior of four California species. 4 
ECOLOGY. 
The members of this genus have been made the object of an ecological 
study by Bueno, who presented his notes in his “Notonecta of North — 
America.” He says in substance that N. undulata hangs from the sur- — 
face almost constantly and its raptorial claws can be seen forming little — 
elevations as it hangs head down. N. insulata seems to prefer to float in 
clear spaces in clear cold pools, about midway between the bottom and — 
surface. “On the other hand, N. irrorata and N. uhleri appear to like to 
hide among the roots of plants growing at the water’s edge, to which 
they cling. The former may at other times also be seen floating below 
the surface, in the shadow cast by bank or fallen tree or broken branch. 
The habits of N. variabilis differ somewhat from the others, since this 
bug prefers to lurk among the water weeds at the bottom.” ; 
Oviposition. Until recently there seemed to be a distinction between — 
the manner of oviposition of the common European species and our 
American forms, the common glauca of Europe placing its eggs in the 
tisues of plants, as noted by Regembart in 1875, and our American 
species affixing them to the surface of plants, as noted by Bueno and 
Essenberg. The writer reviewed the question in the “Egg-laying habits 
of Buenoa margaritacea” at which time he supposed all American species 
placed their eggs upon the plants. In a footnote to his paper recording 
the “Life History of Notonecta undulata,” he recorded the fact that N. 
irrorata places her eggs in plant tissues even better than N. glauca. In 
another paper appearing in the Entomological News “Concerning the 
oviposition of Notonectx,” the writer presented the evidence as to the 
manner of oviposition of the various members of the genus, basing this. 
evidence upon the study of the female ovipositors. The plates submitted | 
with this paper are here reproduced to indicate the interesting study 
