210 THE UNIVERSITY SCIENCE BULLETIN. 
tents. The pulsations of the dorsal vessel can also be seen in this 
instar under the same conditions as before, save that the yolk is, of 
course, totally gone.” 
Third Instar. 
Size. “Length, 4.8 mm.; width, 3 mm.” 
Fourth Instar. 
Size. “Length, 6.5 mm.; width, 4.2 mm. 
“Coloration and other peculiarities slightly more accentuated than in 
the preceding instars. I may here state that just previous to a molt the 
insect is very thick through, especially so in this and the succeeding in- 
stars, and looks fit to burst out of its skin, as it does.” 
Fifth Instar. 
Size. “Length, 8.8 mm.; width, 5.5 mm. 
“T was fortunate enough to have the opportunity of observing the last 
moult in Pelocoris, which I will now describe from my notes taken during 
the process of the ecdysis. 
“The bug hangs from the surface, back up. The outer skin then splits 
along the thorax, and the scutellum of the emerging insect is seen. 
The opening enlarges as the insect gives rhythmical convulsive heaves. 
First the entire thorax comes out; then, with a jerk, the head. It now © 
rests a moment, and in a short space again takes up its motion, withdraw- 
ing the body little by little from the cast-off skin. The dorsum, as yet 
uncovered by the still unexpanded ale and hemelytra, has a coat of air. 
The wings and hemelytra expand as the insect emerges, so that by the — 
time it is entirely out they are fully developed, completely concealing — 
the dorsum abdominis. It takes the insect about ten minutes to go 
through this final transformation. When it is entirely free, it turns 
quickly and hangs back down from the air-filled and buoyant cast skin 
for a moment, until the wings are perfectly expanded. Then it begins © 
to swim about quite rapidly, coming to a rest once more, seemingly re- 
quiring something to hang to. There appears to be an undue amount of 
air under the insect’s wings while it is in this condition, and it remains 
back up while swimming. The tracheal lining may be seen as Pelocoris 
emerges, connecting the sternum with the cast skin. 
“Pelocoris, immediately after the last ecdysis, is entirely of a beautiful 
light green- like aquamarine, including the hemelytra and the limbs 
excepting the tibia, which are dark from the swimming hairs. The ~ 
eyes are a dark ruby-red. The insect gradually grows darker, and 
about four hours after the change it is a mottled dark green. The full 
mature coloration is reached in about 12 hours.” 
Summary. Bueno has presented the only account of the rearing of 
any Naucorid. The eggs of Pelocoris femorata were placed upon sub- 
merged plants. They hatched in about 24 days. The first instar lasts — 
about 8 days; the second instar, 6 to 9 days; third instar, 8 days; fourth 
instar, 10 to 12 days; fifth instar, 16 days. A total, as Bueno tells us, 
of some 77 days for development. Nearly all stages may be taken in the 
summer time in a pool. At Coldwater, Kan., in July, all stages but the 
egg were noted. 
Family CORIXIDA‘. 
A. TAXONOMY OF CORIXIDA. 
Family Characteristics. These medium-sized to small bugs are usually 
marked with bars of yellow and brown. The body is flattened above, and 
the head overlaps the thorax dorsally. The most peculiar thing about 
them is the structure of the beak, which is very short, scarcely if at all 
