88 
THE PERIODICAL CICADA. 
Fig. 3S. — Third larval stage: a, anterior le< 
inner face (original). 
outer face; b, same, 
more properly a mere spine in the first stage, is now very mucli larger 
and broadened at the base into a prominent triangular projection. 
The tarsus is reduced to a horny rudiment about three times as long 
as wide, and is closely applied to the inner surface of the tibial "jaw" 
which extends twice the length of the tarsus beyond the latter. 
This stage, as already stated, is assumed during the first two or 
three months of the 
second year of the in- 
sect's existence and 
lasts nearly two years. 
Third larval stage. — 
Length, G to 8 mm.; 
anterior femora, 1.20 
mm.,- anterior tibiae, 
1.35 mm.; hind tibia?, 
1.85 mm. Eye spots 
still more reduced; numerous parallel rows of short hairs on the head 
are noticeable; hairy armature of legs more distinctly outlined; a row 
of small spines on either side of middle and hind tibiae while the rows 
of bristles on the inner margins of the anterior femora aud tibiae for hold- 
ing the excavated earth 
are well developed. An- 
terior tarsus reduced to 
mere tapering spur about 
two and one-half times as 
long as wide at base. The 
femoral comb has one ad- 
ditional tooth, making 
four in all counting the 
blunt upper cue (fig. 3S). 
The autennal joints de- 
crease in length from the 
basal to the terminal, the 
basal two and the termi- 
nal two being, however, 
of nearly equal length, 
respectively. The wing- 
cases are foreshadowed 
by minute pads. Sexual 
differences very faintly 
discernible. 
The larva is in this stag 
existence. 
Fourth larval stage. — Length, 10 to 15mm. ; anterior femora, 2.10 mm. ; 
anterior tibia?, 2.70 mm. ; hind tibia?, 4 mm. Eye-spots reduced to from 
three to six minute black points, rows of hairs on head easily dis- 
cernible and prominent; sx)ines on femora and tibia? of all legs, and 
Fig. 39. — Fourth larval stage: a, full grown larva, much en- 
larged; b, anterior leg, outer face; c, same, inner face; 
d. outline of femoral corah (original). 
at the completion of the fourth year of its 

