HUNGERFORD: AQUATIC HEMIPTERA. 163 
Second Instar. 
“Form as in the first stage, perhaps a little less broad in proportion 
to the length. Rostrum as before, except that it is perhaps a little less 
stout. Antenne still blunt, short and stout, but not so club-shaped. 
They now begin to show two equal joints. The legs as before, the first 
pair not quite so broad proportionally, with the blunt apical femoral 
tooth beginning to show as an undulation in the inner side of the femur. 
The tibiz of the second and third pair are better provided with spines, 
which increase in number distally. The terminal combs very apparent. 
“Size: Long., 138 mm.; lat. not measured, dimensions being taken from 
moulted skins. 
“Air-tube, 2.7 mm.” 
Third Instar. 
“Form, not greatly changed from the preceding instars, except for 
slight variations in proportions. 
“Rostrum, much as before, but a little slimmer. In this instar the 
tactile hairs at the extr emity of the proboscis are quite noticeable. 
“Antenne appear imper fectly three-jointed in this instar. The suture 
‘separating the basal joint is quite noticeable, and that between the second 
and third joints shows as an incision in the outer margin of the antenne, 
from which a little impressed line goes about half way across. Below 
and above this indentation are two prominences, the beginning of the lobes 
of the segments. Both prominences are armed with a stout spine, that 
of the third joint being about twice as thick as that of the second. The 
‘third joint appears to be pitted at the rounded end. 
“Thorax much narrower, distinctly trisegmentate. Head closer to the 
adult shape, the eyes flattened on the inner side, and quite prominent. 
The wing-pads first appear in this instar, though very small and rudimen- 
tary. 
_ “TLegs and tarsi as before, with the spines of the second and third pair 
of tibie stronger, and the tibial comb more developed. In this instar the 
fringing hairs of the second and third appear, scattered on the femora 
and sparse on the tibiz, butequite long. 
“The false stigmata are quite noticeable at the sides of the abdomen, 
-as darkened spots in the integument. The legs are now shorter than the 
length of the bug, and reach but little beyond the extremity of the respira- 
tory tube. The first pair are not quite as broad proportionally as in the 
previous instars, and show the same undulations of the femora where the 
second tooth will be. 
“Size: Long. (extremity of the rostrum to end of siphon), 19 mm.; 
lat., 1.4 mm.; air-tube, long., 4 mm.” 
Fourth Instar. 
“Form as before. Rostrum but slightly changed. 
“Antenne evidently three-jointed, the prominences more developed, and 
the several spines on the third and second segments quite evident. 
“Tiegs and tarsi as before, with the peculiarities more accentuated. 
They extend only a litle beyond the siphon, and are therefore not as long 
as the body by the length of the thorax. 
-_ “Colour more or less mottled, with banded legs. General tint grayish. 
“Size: Long., 30 mm.; lat. (not taken, specimen being only a cast skin 
n this instar) ; air-tube, long., 7 mm.” 
; Fifth Instar. 
“Form elongate as in the adult. Head, including eyes and exclusive 
ee: rostrum is shorter than the length of the head. Eyes trans- 
