BROOD X—SEPTENDECIM—1919. 5l 
year 1902 was not marked by the recurrence of any 13-year brood, 
and hence the records for that year, for the first time, could practi- 
cally all be assigned without question to Brood X. It had been 
anticipated by the writer and others that many of the records in 
middle and southern Illinois, for example, and northern Missouri, 
which had been referred to the two large 13-year broods, might pos- 
sibly belong to Brood X of the 17-year race. Rather to our surprise, 
however, the old limits of distribution for the three broods in question 
seem to be pretty definitely confirmed. 
Very thorough plans were made early in 1902 to have the entire 
territory over which the brood was expected fully and adequately 
TLL NG! 
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Fic. 13.—Map showing distribution of Brood X, 1919. 
reported, and the responses received by this Bureau were numerous 
and satisfactory for practically the whole area covered by the brood. 
In addition to this several of the entomologists of the different States 
within the range of the brood carried on independent investigations, 
and the records obtained by them, most of which have been pub- 
lished since, have been incorporated with the reports received by this 
Bureau. All of the records agree in showing the substantial accuracy 
of the limits of this brood as hitherto platted. The State records 
available and used in the following list of States and counties, so far 
as they represent counties new to our records, are those reported by 
Pettit for Michigan, Smith for New Jersey, Sanderson for Delaware, 
