r= 
HUNGERFORD: AQUATIC HEMIPTERA. 225 
The attachment disc of the egg is smaller than in some of the other 
species. Two eggs are figured on pl. XXVIII, fig. 15. These are drawn to 
same scale and show the difference in size and shape between the newly 
laid egg and the older egg. 
First Instar. 
Size. Length, 1.09 mm.; width of body, 0.65 mm.; width of head, 
0.494 mm.; space between eyes, 0.299 mm. 
Shape. Flat, width of body greater than one-half the length. As 
time for first molt approaches the body becomes thicker in dorso-ventral 
line, a fact which holds for the other stages as well. 
Color. Eyes dark red, body mottled with smoky grayish-black. Pat- 
tern distinct, as shown in pl. XXVII, fig. 7. Pattern about as described 
for second instar, with the exception of mesothorax, where irregular 
blotches of dark pigment replace the transverse arcuate bands described 
below. 
Structural Peculiarities. The limbs in this stage are proportionately 
larger than in following instars. The stout hairs fringing the limbs 
are not as definitely arranged for a given purpose as later. The fringe 
of swimming hairs on hind limbs made up of few hairs. The middle 
limbs, which in the adult are so slender and long, are thick and no 
longer than the hind limbs. The femur is as long as tibia and tarsus 
together, which are subequal. Tarsus is 1-segmented, and ends in two 
long slender claws, which nearly equal the length of tibia and tarsus 
together. 
| Hind limbs not conspicuously flattened as in later forms, the swim- 
ming hairs few, perhaps a dozen in each row, and confined to the tarsal 
segment, which ends in a pair of almost spine-like claws. These claws 
are about half the length of tarsus, and straight, save for a slight devia- 
tion from a straight line at a point two-thirds the distance from their 
_ base. 
The dorso-caudal side of hind tibia with am irregular row of 10 to 12 
short, stout spines. A few other less conspicuous spines upon this seg- 
ment and two longer ones on caudal margin of distal end of this seg- 
_ ment. 
} Middle Leg. Two short spines on anterior margin of femur, and two 
long ones near distal end. Tibia sparsely covered with short, stout 
hairs, a long one on anterior margin near base, two near distal end. 
_ The marginal series of spines as delineated. 
Caudal Segment. Pair of short peg-like spines astride the median 
line. Caudo-lateral angle of body with five pairs of long spines, 
cephalad of which are two short ones. The penult segmental margin, 
_ 12 long spines cephalad of which are two or three short ones. The ante- 
penult segmental margin, a pair of subequal long spines and cephalad 
of these two or three shorter ones. 
Second Instar. 
Size. Length, 1.638 mm.; width of body, 0.858 mm.; width of head, 
