34 THE PERIODICAL CICADA, 
Future APPEARANCES. 
During the next seventeen years broods of the 17-year and 13-year 
races of the periodical Cicada will occur as follows: 
Table of future appearances. 
| 
Year 17-year race. | 13-year race. Year. 17-year race. 13-year race. 
| | 
19072225) EXcVi New?....| XIX Major......- 1916...| VII Minor...) XXVIII] No record. 
1908....| XVI | Minor....| XX Minor sees |} 1917...| VIDE |....do.:.| XXEX | New? 
1 QUO SONS Wall |WIN erat same eNCICN Ieee doverees | TEA WSS [SRE RGIO) 2 Sal DOK Do. 
191OE == il iMbbetonmes 3) 2.O;0U0 Boose 00s 2552 |) MOTOS Sa Xe Major-..| XVIII | Minor. 
DOME = II Mayor= ao] Sexes Maton). sos | StO202e ENG ll SM Omen! Pee NGID NG Major. 
TIDE eee lh ome 5) eel Ose | eNO NGA ING Wire ee | 1921...) XII | New?..- xX Minor. 
LOIS ose) Ves aa Gor) eXOnays No record . .|| 1922...| XIII | Major..| XXI Do. 
1914._.. V Eek Se olf DG-OVIT Pi huaoheye aa ee NlO23ce ENG: al eon dOL melee NGLIL Do. 
1915 VI Minors 22 |) exe Vl ING ween ene | eee XV New?...| XXIII | 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 by 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 may be forthcoming at 
any time, although it is evident that the breaking up of the 13-year 
race into broeds has not proceeded to anything 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 in the same year. This is purely accidental, and in point 
of fact the same two broods could only come together once in 221 
years. The greatest Cicada year of recent times was 1868, when 
Brood X, the largest of the 17-year 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 increase 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 INFORMATION. 
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. Jt 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 
