120 
THE PERIODICAL CICADA. 
able; 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 tlie inner margins of the anterior femora and tibite for holding the 
excavated earth are well developed. xVnterior tarsus reduced to a mere 
tapering spur about two and one-half times as long as wide at base. 
Tlie femoral comb has one additional tooth, making four in all, count- 
ing the blunt upper 
one (fig. 49) . The an- 
tenna! joints decrease 
in length from the 
basal to the terminal, 
the basal two and the 
terminal two being. 
Fig. 49. — Third lan-al stage: a, anterior leg, outer lace; b, same, ho WC Ver of 
inner face. (Author's illustration.) , , ' ^ 
equal length, 
nearly 
respec- 
Sexual 
tivety. The wing cases are foreshadowed by minute pads 
differences very faintly discernible. 
The larva is in this stage at the completion of the fourth year of its 
existence. 
Fourth larval stage. — Length, 10 to 15 mm.; anterior femora, 2.40 
mm.; anterior tibiae, 2.70 
mm.; hind tibiae, 4 mm. 
Eye-spots reduced to 
from three to six minute 
black points, rows of 
hairs on head easily dis- 
cernible and prominent; 
spines on femora and 
tibiae of all legs, and par- 
ticularty the anterior 
pair, more numerous and 
longer and stouter than 
in the preceding stages. 
The anterior tibia has a 
small tooth withm the 
larger blunt subapical 
one. The femoral comb 
has again an additional 
tooth, making five in all. 
^Vntenna^ as in the preced- 
ing stage. Rudimentary wing cases somewhat more prominent than 
in the last stage, but still inconspicuous. (See fig. 50.) 
The larva is in this stage at the com])letion of the eighth year of its 
existence, and the stage probably lasts three or four years. 
Fig. .50.— Fourth lan-al stage: a, full grown lars'a. much en- 
larged; b, outline of femoral comb: c, anterior leg, outer face; 
(Autlior's illustration.) 
d, same, inner face. 
