SUMMARY OF FUTURE APPEARANCE. 45 
be substantiated in future the distribution will not extend beyond the 
dividing range of the Rocky Mountains. The connection lietween the 
distribution of this insect and the botanical, geological, and topographi- 
cal characteristics of the country forms a very interesting subject for 
consideration, and I hope to consider it in a future edition of this Bulletin. 
The following summaries may be made, for convenience, from the fore- 
going chronological account, the Roman numerals indicating the num- 
ber of the brood, and the asterisk the 13-year broods. 
During the next seventeen years there will occur broods of the Peri- 
odical Cicada somewhere or other in the United States, in the following 
years : 
1885. VII* and XXII. 
188G. I. 
J888. Yarn! X*. 
1889. VIII. 
1891. IX. 
1893. XI and XVI*. 
1894. XII and XVIII*. 
1895. II* and XIII. 
1896. IV* and XIV. 
1897. VI* and XV. 
1898. VII* and XVII. 
1899. XIX. 
1900. XX, 
1901. X* and XXI. 
Thus every year except 1887, 1890, and 1892, will, during the next 
seventeen years, be somewhere a Cicada year; and it will be noticed 
that the 13-year broods invariably concur with some 17-year brood, a 
fact which is worthy of note and which leads to interesting speculation 
as to the origin of the former. 
It further appears that the number of distinct broods appearing in 
different years within the same geographical limits are as follows: 
Alabama.— Two broods; years 1894 [XVIII*] and *9(> [IV*], and 
probably another in 1SS8 [X*j. 
Arkansas.— Two broods; years 1885 | VII*] and '94 [XVIII*]. 
Colorado.— One brood; year 1891 [IX]. 
Connecticut.— Two broods; years 1886 [I], and 1894 [XII]. 
DELAAVARE. — Two broods: years 1SS5 [XXII] and '89 [VIII]. 
District of CoLUMin a.— Two broods: years 1885 [XXII] and >94 
Florida.— One brood: year 1896 [IV*]. 
Georgia.— Five broods j years L885 [two broods VI I* and XXII . 
'93 [XVI*], '94 [XVIII*], and '95 [II*]. 
Illinois.— Six broods; years 1885 [VII*], '88 [V], '89 [VI 11 . 
[XI], '94 [XVIII*], and >95 [XIII]. 
