10 THE PERIODICAL CICADA. 
nonp'ihlicalioii of Doctor Siuilli's jiionotrrapli," those broods would 
have failed ot the a})iin(hint j)rool on which theynowrest. The race 
name of tredeciin for the 13-year broods was sutrt^ested by Walsh and 
Iviley without knowledge of its earlier use by Doctor Phares. The 
hitter's early articles in the Republican are lost altogether, the author 
himself not being able to recover them in later years, and the credit 
for the name tredecim for the 13-year race, following the customary 
rules, should go to Walsh and Riley. 
The discover}^ of the 13-year Southern race was of vast assistance 
in clearing up the confusion which had attended the study of the 
different ])roo(ls of this insect and enabled Walsh and Riley to sepa- 
rate some sixteen distinct broods, three of which belong to the tre- 
decim race, and later enabled Prorcssor Riley, with the aid of Doctor 
Smith's paper, to increase the number of tredecim broods to seven 
and the total of the broods to twent3^-two, twenty-one of which the 
records of subsecjuent appearances have proved to be valid. 
Doctor Smith's remarks in his manuscript chapter on geographical 
tribes and districts present the status of the 17-year and 13-year 
races very clearly. He sa3^s: 
There are two divisions or tribes, differing from each other only in the periods of 
their lives; the one and much the larger division living 17 years, and the other 
13; hence the impropriety of the specific name se/)^enriecm. * * * The anatomy 
of the insects of both divisions is precisely the same, but septendedm does not of 
course apply to the Southern division, whose lives are but 13 years. Shall we call 
the latter Cicada tredecim? Why there is this difference in the periods of lives of the 
two tribes we can not explain. It is not the climate that causes it, as a moment's 
reflection will prove. If that were the cause the difference would be more gradual. 
For example, in northern New York they would have been, say, 17 years; in Pennsyl- 
vania, 16; in Maryland and Virginia, 15; in North Carolina and Tennessee, 14, and 
in South Carolina, etc., 13 years in completing their existence. But that is hot the 
case. The difference of years takes place abruptly on and about the line of 34° 
and 35° of north latitude, on the north side of which the period is 17 years and on 
the south 13 years. 
While Doctor Smith is hardl}^ justified in the last statement, it is 
nevertheless true that the 17-year race is northern and the 13-year 
race is southern. The territory of the two races is graj^hically shown 
m figures 2 and 3, and is described in detail and mapped for all the 
broods in a later section. 
In this bidletin the two forms of the periocHcal Cicada have ])een 
designated as ''races," adopting the position taken by Professor Riley 
and the majority of the writers on this insect, rather than consider- 
ing tluMu to be (Hstinct species, as is held by some specialists. Pro- 
fessor Riley and others opposed the icU^a of their being specifically 
thstinct, not only because of their practical identity in general cliar- 
«A summary, with extracts, of this manuscript made by Professor Riley is the 
writer's source of information on this valuable paper, which, while containing jnuch 
error and wrong inference, vet indicates canM'ul studv and accurate observation. 
