226 THE UNIVERSITY SCIENCE BULLETIN. 
Shape. A little more elongate than in first instar, the width now 
about half the body width. 
Color. Eyes very dark red, as are the dorsal abdominal glands. 
Cephalic aspect of head shows the cephalic end of the median dark longi- 
tudinal band, noted below. This band extends down upon the front to 
the level of the lower inner angles of the eyes. A dark spot lies lat- 
erad of the lower end of the median band, about three-fifths to two- 
thirds the distance to the inner angle of the eye. Dorsal aspect: head 
with median longitudinal smoky band visible from front to highest point 
of vertex. Between the caudal end of this line and the eyes lie two 
pairs of dark, more or less elongate, spots. The prothorax is marked 
on each side with two dark, roughly triangular spots of unequal size, 
their apices directed toward the margins. The smaller spots just laterad 
of median line and the larger ones laterad of these. The prothorax 
often marked by a transverse band on caudal margin. The mesothorax 
is marked by three pairs of very irregular and often indefinite, smoky 
blotches of unequal size. The abdomen is marked by reddish transverse 
bands that follow the abdominal sutures. These give way to triangular 
sooty blotches at the margins. The two large, dark dorsal glands have 
arcuate anterior margins and convex posterior margins. A dark circular 
spot marks the anal opening. The middle limbs have the joint between 
femur and tibia slightly smoky, and the tarsus is crossed by faint median 
band. The tibio-tarsal joint of hind leg is dark and a band crosses the 
middle of the tarsus. A dark spot on the hind tarsus is characteristic of 
all the nymphs of this species, and mark them from the nymphs of 
Arctocorixa alternata taken at the same time. 
Structural Peculiarities. The hairs on limbs in more definite series. 
Swimming fringe of hind legs still confined to margins of tarsus for 
the most part, but composed of a larger series of more closely set hairs, 
some 40 in number. The claws of the hind tarsus are now one-third the 
length of this segment, and appear incised about midway of their length. 
The relative lengths of limb segments much as in the previous instar, 
but the entire limb more slender. The marginal series of spines as 
delineated in the figure. The pair of peg-like spines astride the median 
line on caudal margin in this and all other instars. A cluster of five 
long spines at caudo-lateral angle of last segment and about five short — 
ones anteriorly. The penult segment of abdomen is margined by five 
spines, the second one from the caudal margin elongate. The ante- ; 
penult segment of abdomen is margined by about seven spines, the first, | 
second and fourth longer than the others, the second one being Ewicels 
as long as any of the rest 
Third Instar. 
Size. Length, 2.21 mm.; width of body, 1.04 mm.; width of head, 
0.806 mm.; distance between eyes, 0.286 mm. 
Shape. Length now two and a fifth times the width. 
Color. The face has the dark blotches between the lower inner angle 
of eye and the dark longitudinal median line of former instars. In 
dorsal view the head is marked either side of the longitudinal median 
