THK CI.ASSIFKWTTON OK TIIK 1?K(M)I)S. 25 
It is possil)l(^ Id c()1U'(MV(> also of conditions wliicli would icsuli in 
tlie accoleralioii or rolardalion in the dc^vclopincni of an (Milirc* l)rood 
or l)i'()ods of the Cicada, sucli as variation in diinatic conditions, 
i:ci)loi:ical (dianirc^s. oi- cliani:(>d conditions of the lo|)oL::i'a])liy of tlic 
connti'v. incdiidini!: the tdiai'actcr of the vci^c^tat ion. 
In this oi- oth(M' ways, at any rato, tlic Cicada has l)cconic hrol^cn 
np into a liw^c nninl)cr of distinct ])i-oods, oft(Mi cox'crinL: different 
t(M'iMloi"y, hnt not n(>c(\ssarily so (h)ini::, ('acli, liowcx'cr, maiiuainini:; 
its rcixnlai" time of app(^aranc(\ 
Th(^ shi^ht hnt constant ten(hMicy to variation ^\]n(•ll lias ])ron<r]it 
into exislenc(^ tlu> hioods now so well marked, coiitinncnl indefiniteh', 
wonld so ])reak up and scatter the present broods as to ultimately 
o1)scm'(^ tluMn altoiretlier, and the overlaj^ping of districts and tlic 
variation in time of appearance would lead to a rather o^eneral occur- 
rence every year of the p(M"i()dical Cicada throughout its range, the 
long period for development, however, still persisting. Anticipating 
sucli an outcome from the intermixture and overlapping merely of 
different broods, Doctor Smith (Smith MS.) rather mournfidly says: 
"In those times, if these sayings of mine should be thought of, they 
will be ridiculed as a superstitious legend of the olden times." 
The Classification of the ])Roods. 
In the first edition of this bulletin the numerical designation of the 
broods of the two races suggested by Professor Riley was followed. 
This numbering has, however, objectionable features and obscures 
the relations of the broods of each race to each other. To overcome 
these objections a new system of numbering was proposed by the 
writer," which has since been generally adopted. The reasons for 
making this change and the numerical designations proposed are here 
reproduced with little change from the publication cited. 
The earlier ^vTiters, viz, Prof. Nat. Potter, Dr. William T. Harris, 
and Dr. G. B. Smith, classified the broods solely according to the 
years of tlieir appearance. The unpublished register left by Doctor 
Smith includes every important brood now known classified accord- 
ing to race, and gives the localities for one additional l)r()()d, the 
(wistence of which seems not to have been confirmed. Though 
lacking an}" special designation for the broods, Doctor Smith's classi- 
lication is as complete and accurate as that published b}^ Doctor 
Kiley and since followed by all later writers. ^ Dr. Asa Fitch was the 
first to introduce a numbering system for the different l»roods. ouw- 
merating nine altogether, but his data were very limited and h(> was 
not aware of the thirteen-year southern period, and there necessarily 
resulted no little confusion of th(> broods of the two races. The 
«Riill. 18, n. s.. T)iv. Eiil., V. S. I).|.i. A-ri... j.]). 52-58, ]898. 
& See Appendix. 
