34 
THE PERIODICAL CICADA. 
Future Appearances. 
Durint^ the next seventeen years broods of the 17-year and 13-year 
races of the periodical Cicada will occur as follows: 
Tabic of f II tun appearances. 
Your. 
17-vt>ar race. 
13-year race. 
1907.... 
1908....' 
1909;... 
1910....' 
1911....' 
1912.... 
1913.... 
1914. ...| 
1915.... 
XV 
XVI 
XVII 
I 
II 
III 
IV 
V 
VI 
Now?.... 
XIX 
Minor.... 
XX 
New?.... 
XXI 
Minor.... 
XXII 
Major.... 
XXIII 
....do.... 
XXIV 
....do.... 
XXV 
....do.... 
XXVI 
Minor.... 
XXVII 
Year. , 17-year race. 
13-year race. 
Major 1916,..! 
Minor i 1917. ..I 
....do 1918... I 
....do .. 1919...' 
Major 1920. ..i 
New? I 1921... 
No record . . 1922... 
Minor ;! 1923...' 
New? 1 1924... 
Il i 
VII 
Minor... 
XXVIII 
VIII 
....do... 
XXIX 
IX 
....do... 
XXX 
X 
Major... 
XVIII 
XI 
Minor... 
XIX 
XII 
New?... 
XX 
XIII 
Major . . 
XXI 
XIV 
....do... 
XXII 
XV 
New?... 
XXIII 
No record. 
New? 
Do. 
Minor. 
Major. 
Minor. 
Do. 
Do. 
Major. 
In this table the large or important broods are designated as 
major; the small or scattering broods as minor. In the latter class 
the new and often doubtful broods suggested b}^ the writer also fall. 
In the case of a few numbers assigned to the 13-year race no records 
of occurrence have been reported, but such maj^ be forthcoming at 
any time, although it is evident that the breaking up of the 13-year 
race into broods has not proceeded to anj^thing like the extent that 
it has in the 17 -year race. 
It will be noticed that as a rule a 17-year and 13-year race are 
associated m the same ^^ear. This is purely accidental, and in point 
of fact the same two broods could only come together once in 221 
years. The greatest Cicada 3'ear of recent times was 1868, when 
Brood X, the largest of the 17-5"ear race, appeared in conjunction 
with Brood XIX, the largest of the 13-year race. These two broods 
will have their next joint occurrence in the year 2089, when perhaps 
the mcreasc of settlement and the changed character of vegetation 
and superficial conditions over their respective ranges may have 
entirely eliminated them except for stragglers. 
THE DISTRIBUTION OF THE PERIODICAL CICADA. 
SOURCES OF INIOKMATIO.N. 
The records on which are based the present information of the dis- 
tribution of the several broods of the periodical Cicada have been the 
accumulation of more than two hundred years, and particularly dur- 
ing the last fifty years they have assumed a most voluminous char- 
acter, and any effort to discuss the subject at all minutely would 
expand this publication beyond reasonable limits. It is impossible, 
therefore, to detail the evidence which has been used in determining 
brood limits or even to summarize the voluminous historical and 
chronological records on which this distribution rests. All that is 
possible is to continue the plan followed in Bulletin 14 of limiting 
