msroKV OK THK LARVAL AND ITPAL srA(;j:s. 117 
of ii:r()wtli will \ary coiisidcM-ahly in sizc^ of the body and I lie softer 
parts, represent inix perhaps a dilVercnce in n^^c in some cases of one 
or two years, but the hard parts will prescMit a very nnifoi-ni si/.c and 
eharacter. 
The j)eeuliar structure of tlu^ (Mdari2:(Ml antei'ior le^^s furnisho p( i- 
liaps the best means of distinLrnishinii: the adolesc(>nt sta^^cs of this 
sp(H'i{»s from other cicadas and the modilication which t hoc limhs 
undergo with the ditferent molts the ])est nuMins of del (Mini nin<i; the 
aj2:e of the larva\ The peculiarities of tlu^ anterior Ic^s consist in the 
enormous (MdarirtMnent of the femora and tihia> and tluMi- (lc\(>lopmcnt 
into structures wliich resemble somewhat the cuttini:; mandibles of 
]>itin<r ins(H'ts or r(>call tlu^ fossorial foivleijjs of ihv mole cricket. The 
peculiar structure of tluvse l(»srs is in fact especially desin-ned foi- (Tilc- 
^in^, teariui^:, and transj^ort iuii; (\irtli in tlie course of tlu* itisect's sub- 
terranean life. As alr(\uly indicated, the amount of burrowini^ in 
th(^ eaily stages is not necessarily very great in any one y^'ar, but dur- 
ing the entire seventeen years conditions may occasionally arise which 
will demand a considin'able activity on the part of the young Cicada. 
Tlu> d(>tails of the structure of tlie front legs, wdiich are given in the 
technical description of this species, are quite characteristic and 
diverge notably from the similar parts of other species. The anterior 
tarsus of the periodical Cicada exhibits also a rather ]^(Muliar meta- 
morphosis during the adolescent life of the species. In other words, 
during the first larval stage and in the pupal stage it is similar to the 
other tarsi but considerably longer, being attached to the iimer side 
of the greatly enlarged tibia and at a considerable distance from the 
clawlike ti]:> of the latter. The fore tarsi are of service to the young 
larva in \\alking and climbing and in the same way to the ))upa after 
its emergence from the soil, facilitating its climbing trees or other 
ol)jects; in other words, covering the periods between the hatching 
and entering the soil and betw^een the emergence of the ])upa and l1i(^ 
disclosure of the imago. During its long subterranean life, however, 
these long, .slender tarsi, being distinctly in the way in digging in the 
earth and of no .service, become rudimentary with the first moll and 
nearly disa])]>ear in the subsecpient larval stage. They reapjx^ar in 
th<' iir>t })Ui)al stag<\ but in this and the sul)se(|uent puj)al stage, 
while the insect is still below the soil, they are folded back along the 
tibiir, so as to be practically functionless (se(» (ig. 51), and are only 
unfolded and brought into service after the pupa has emerged from 
the ground. 
Tlie more detailed description of the different stages which follows 
will facilitate^ the easy recognition of any particular stage. The chief 
points to be considered in determining both the age of the larva and 
whether or not it belongs to the j^eriodical s]>ecies are the measure- 
ments of the corre.sj)onding parts of the legs and antemue, but i)ar- 
