THE rLASSIFICATION OK THK HKOODS. ' 27 
tlireo years, ihcre follow s(>\(mi siic('(»ssi\ (> years in wliidi no IM-xcar 
broods occ-iii". 
riulor tlie siipposil ion (hat 1 1\(> dilliMcnl hroods of 1 lie IT-ycarand 
lo-ycar" races s])i'anL:.- in the lUMnote past frctni an original brood of 
each, it would naturally follow tliat tlu> hi-oods most closely related 
in time would also pr(^-^(Mlt a closer I'clat ionsliij) in theii- F'aniic and 
this, in fact. pro\(»s to \)o ucMUM-ally tru(\ 
'I'o sliow this rc^lat ionsliij) and to indicate* th(> natural order of their 
occui'r(Mic(\ 1 ha\(» suji:si'est(Ml a new eiuimei'at ion of the hioods in 
which the two rac(\s ar(^ s(»parated — the 17-year l)i-oods cominij: first, 
followed, for conviMU(Mic(^ merely, b}^ the 13-year bioods. Thus 
Brood XI of the 17-year race becomes Brood 1, and the others are 
nund)ere(l in the reuidar order of their occurrence, except that 1 
have assij^ned a brood jiinnber to each of the seventeen years. This 
leaves Broods XII, XA', and XYII, as newly numbered, without 
any definite colonies, so far accepted, as representatives of established 
broods. As will be show^n later, however, there are records which 
indicate the existence of small or scattering broods filling the three 
gaps mentioned in the 17-year series. 
In renumbering the broods of the 13-year race I have continued 
for convenience from the end of the series of the 17-year race, the first 
13-year l)rood becoming Brood XYIII, and I have assigned brood 
numbers to each year of the 13-year period, making a total enumera- 
tion of the broods of both races of XXX. As already indicated, six 
of the numbers given to the 13-year race have had no brood assigned 
to them, although records have been secured which seem to indicate 
the existence of scattering broods filling some of the gaps, as will be 
noted in the records given further on. 
It does not necessarily follow, in fact it is quite unlikely, that Brood 
I, as here designated, is the original or oldest brood of the 17-year 
race. Undoubtedly some of the 17-year broods, perhaps half or more 
of them, originated by retardation of individuals, and perhaps half 
by acceleration of individuals; so that the original brood, if it still 
exists, is more likely to be one of the intermediate ones. Brood X, 
being the largest of the 17-year broods, perhaps has best claim to 
this distinction. 
For the same reasons an intermediate brood in the 13-year series 
is doubtless the original brood of the 13-}' ear race, and this title may 
possibly belong to Brood XIX, which has the widest range of all the 
broods of the 13-year race. The fewer number of broods in this race 
would seem to indicate that it is of later origin than the 17-year race, 
and tjiis belief is further justified by the fact of ita occupying, in the 
main, a territory of later geological formation. 
The following table, beginning with 1893, wlien the initial ])ro()ds 
of both the 17-year and the 13-year series appeared in conjunction, 
